xref: /linux/net/core/skbuff.c (revision 65249feb)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	Routines having to do with the 'struct sk_buff' memory handlers.
4  *
5  *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
6  *			Florian La Roche <rzsfl@rz.uni-sb.de>
7  *
8  *	Fixes:
9  *		Alan Cox	:	Fixed the worst of the load
10  *					balancer bugs.
11  *		Dave Platt	:	Interrupt stacking fix.
12  *	Richard Kooijman	:	Timestamp fixes.
13  *		Alan Cox	:	Changed buffer format.
14  *		Alan Cox	:	destructor hook for AF_UNIX etc.
15  *		Linus Torvalds	:	Better skb_clone.
16  *		Alan Cox	:	Added skb_copy.
17  *		Alan Cox	:	Added all the changed routines Linus
18  *					only put in the headers
19  *		Ray VanTassle	:	Fixed --skb->lock in free
20  *		Alan Cox	:	skb_copy copy arp field
21  *		Andi Kleen	:	slabified it.
22  *		Robert Olsson	:	Removed skb_head_pool
23  *
24  *	NOTE:
25  *		The __skb_ routines should be called with interrupts
26  *	disabled, or you better be *real* sure that the operation is atomic
27  *	with respect to whatever list is being frobbed (e.g. via lock_sock()
28  *	or via disabling bottom half handlers, etc).
29  */
30 
31 /*
32  *	The functions in this file will not compile correctly with gcc 2.4.x
33  */
34 
35 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
36 
37 #include <linux/module.h>
38 #include <linux/types.h>
39 #include <linux/kernel.h>
40 #include <linux/mm.h>
41 #include <linux/interrupt.h>
42 #include <linux/in.h>
43 #include <linux/inet.h>
44 #include <linux/slab.h>
45 #include <linux/tcp.h>
46 #include <linux/udp.h>
47 #include <linux/sctp.h>
48 #include <linux/netdevice.h>
49 #ifdef CONFIG_NET_CLS_ACT
50 #include <net/pkt_sched.h>
51 #endif
52 #include <linux/string.h>
53 #include <linux/skbuff.h>
54 #include <linux/skbuff_ref.h>
55 #include <linux/splice.h>
56 #include <linux/cache.h>
57 #include <linux/rtnetlink.h>
58 #include <linux/init.h>
59 #include <linux/scatterlist.h>
60 #include <linux/errqueue.h>
61 #include <linux/prefetch.h>
62 #include <linux/bitfield.h>
63 #include <linux/if_vlan.h>
64 #include <linux/mpls.h>
65 #include <linux/kcov.h>
66 #include <linux/iov_iter.h>
67 
68 #include <net/protocol.h>
69 #include <net/dst.h>
70 #include <net/sock.h>
71 #include <net/checksum.h>
72 #include <net/gso.h>
73 #include <net/hotdata.h>
74 #include <net/ip6_checksum.h>
75 #include <net/xfrm.h>
76 #include <net/mpls.h>
77 #include <net/mptcp.h>
78 #include <net/mctp.h>
79 #include <net/page_pool/helpers.h>
80 #include <net/dropreason.h>
81 
82 #include <linux/uaccess.h>
83 #include <trace/events/skb.h>
84 #include <linux/highmem.h>
85 #include <linux/capability.h>
86 #include <linux/user_namespace.h>
87 #include <linux/indirect_call_wrapper.h>
88 #include <linux/textsearch.h>
89 
90 #include "dev.h"
91 #include "netmem_priv.h"
92 #include "sock_destructor.h"
93 
94 #ifdef CONFIG_SKB_EXTENSIONS
95 static struct kmem_cache *skbuff_ext_cache __ro_after_init;
96 #endif
97 
98 #define SKB_SMALL_HEAD_SIZE SKB_HEAD_ALIGN(MAX_TCP_HEADER)
99 
100 /* We want SKB_SMALL_HEAD_CACHE_SIZE to not be a power of two.
101  * This should ensure that SKB_SMALL_HEAD_HEADROOM is a unique
102  * size, and we can differentiate heads from skb_small_head_cache
103  * vs system slabs by looking at their size (skb_end_offset()).
104  */
105 #define SKB_SMALL_HEAD_CACHE_SIZE					\
106 	(is_power_of_2(SKB_SMALL_HEAD_SIZE) ?			\
107 		(SKB_SMALL_HEAD_SIZE + L1_CACHE_BYTES) :	\
108 		SKB_SMALL_HEAD_SIZE)
109 
110 #define SKB_SMALL_HEAD_HEADROOM						\
111 	SKB_WITH_OVERHEAD(SKB_SMALL_HEAD_CACHE_SIZE)
112 
113 /* kcm_write_msgs() relies on casting paged frags to bio_vec to use
114  * iov_iter_bvec(). These static asserts ensure the cast is valid is long as the
115  * netmem is a page.
116  */
117 static_assert(offsetof(struct bio_vec, bv_page) ==
118 	      offsetof(skb_frag_t, netmem));
119 static_assert(sizeof_field(struct bio_vec, bv_page) ==
120 	      sizeof_field(skb_frag_t, netmem));
121 
122 static_assert(offsetof(struct bio_vec, bv_len) == offsetof(skb_frag_t, len));
123 static_assert(sizeof_field(struct bio_vec, bv_len) ==
124 	      sizeof_field(skb_frag_t, len));
125 
126 static_assert(offsetof(struct bio_vec, bv_offset) ==
127 	      offsetof(skb_frag_t, offset));
128 static_assert(sizeof_field(struct bio_vec, bv_offset) ==
129 	      sizeof_field(skb_frag_t, offset));
130 
131 #undef FN
132 #define FN(reason) [SKB_DROP_REASON_##reason] = #reason,
133 static const char * const drop_reasons[] = {
134 	[SKB_CONSUMED] = "CONSUMED",
135 	DEFINE_DROP_REASON(FN, FN)
136 };
137 
138 static const struct drop_reason_list drop_reasons_core = {
139 	.reasons = drop_reasons,
140 	.n_reasons = ARRAY_SIZE(drop_reasons),
141 };
142 
143 const struct drop_reason_list __rcu *
144 drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
145 	[SKB_DROP_REASON_SUBSYS_CORE] = RCU_INITIALIZER(&drop_reasons_core),
146 };
147 EXPORT_SYMBOL(drop_reasons_by_subsys);
148 
149 /**
150  * drop_reasons_register_subsys - register another drop reason subsystem
151  * @subsys: the subsystem to register, must not be the core
152  * @list: the list of drop reasons within the subsystem, must point to
153  *	a statically initialized list
154  */
drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,const struct drop_reason_list * list)155 void drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,
156 				  const struct drop_reason_list *list)
157 {
158 	if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
159 		 subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
160 		 "invalid subsystem %d\n", subsys))
161 		return;
162 
163 	/* must point to statically allocated memory, so INIT is OK */
164 	RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], list);
165 }
166 EXPORT_SYMBOL_GPL(drop_reasons_register_subsys);
167 
168 /**
169  * drop_reasons_unregister_subsys - unregister a drop reason subsystem
170  * @subsys: the subsystem to remove, must not be the core
171  *
172  * Note: This will synchronize_rcu() to ensure no users when it returns.
173  */
drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys)174 void drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys)
175 {
176 	if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
177 		 subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
178 		 "invalid subsystem %d\n", subsys))
179 		return;
180 
181 	RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], NULL);
182 
183 	synchronize_rcu();
184 }
185 EXPORT_SYMBOL_GPL(drop_reasons_unregister_subsys);
186 
187 /**
188  *	skb_panic - private function for out-of-line support
189  *	@skb:	buffer
190  *	@sz:	size
191  *	@addr:	address
192  *	@msg:	skb_over_panic or skb_under_panic
193  *
194  *	Out-of-line support for skb_put() and skb_push().
195  *	Called via the wrapper skb_over_panic() or skb_under_panic().
196  *	Keep out of line to prevent kernel bloat.
197  *	__builtin_return_address is not used because it is not always reliable.
198  */
skb_panic(struct sk_buff * skb,unsigned int sz,void * addr,const char msg[])199 static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
200 		      const char msg[])
201 {
202 	pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
203 		 msg, addr, skb->len, sz, skb->head, skb->data,
204 		 (unsigned long)skb->tail, (unsigned long)skb->end,
205 		 skb->dev ? skb->dev->name : "<NULL>");
206 	BUG();
207 }
208 
skb_over_panic(struct sk_buff * skb,unsigned int sz,void * addr)209 static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
210 {
211 	skb_panic(skb, sz, addr, __func__);
212 }
213 
skb_under_panic(struct sk_buff * skb,unsigned int sz,void * addr)214 static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
215 {
216 	skb_panic(skb, sz, addr, __func__);
217 }
218 
219 #define NAPI_SKB_CACHE_SIZE	64
220 #define NAPI_SKB_CACHE_BULK	16
221 #define NAPI_SKB_CACHE_HALF	(NAPI_SKB_CACHE_SIZE / 2)
222 
223 #if PAGE_SIZE == SZ_4K
224 
225 #define NAPI_HAS_SMALL_PAGE_FRAG	1
226 #define NAPI_SMALL_PAGE_PFMEMALLOC(nc)	((nc).pfmemalloc)
227 
228 /* specialized page frag allocator using a single order 0 page
229  * and slicing it into 1K sized fragment. Constrained to systems
230  * with a very limited amount of 1K fragments fitting a single
231  * page - to avoid excessive truesize underestimation
232  */
233 
234 struct page_frag_1k {
235 	void *va;
236 	u16 offset;
237 	bool pfmemalloc;
238 };
239 
page_frag_alloc_1k(struct page_frag_1k * nc,gfp_t gfp)240 static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp)
241 {
242 	struct page *page;
243 	int offset;
244 
245 	offset = nc->offset - SZ_1K;
246 	if (likely(offset >= 0))
247 		goto use_frag;
248 
249 	page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
250 	if (!page)
251 		return NULL;
252 
253 	nc->va = page_address(page);
254 	nc->pfmemalloc = page_is_pfmemalloc(page);
255 	offset = PAGE_SIZE - SZ_1K;
256 	page_ref_add(page, offset / SZ_1K);
257 
258 use_frag:
259 	nc->offset = offset;
260 	return nc->va + offset;
261 }
262 #else
263 
264 /* the small page is actually unused in this build; add dummy helpers
265  * to please the compiler and avoid later preprocessor's conditionals
266  */
267 #define NAPI_HAS_SMALL_PAGE_FRAG	0
268 #define NAPI_SMALL_PAGE_PFMEMALLOC(nc)	false
269 
270 struct page_frag_1k {
271 };
272 
page_frag_alloc_1k(struct page_frag_1k * nc,gfp_t gfp_mask)273 static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp_mask)
274 {
275 	return NULL;
276 }
277 
278 #endif
279 
280 struct napi_alloc_cache {
281 	local_lock_t bh_lock;
282 	struct page_frag_cache page;
283 	struct page_frag_1k page_small;
284 	unsigned int skb_count;
285 	void *skb_cache[NAPI_SKB_CACHE_SIZE];
286 };
287 
288 static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
289 static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache) = {
290 	.bh_lock = INIT_LOCAL_LOCK(bh_lock),
291 };
292 
293 /* Double check that napi_get_frags() allocates skbs with
294  * skb->head being backed by slab, not a page fragment.
295  * This is to make sure bug fixed in 3226b158e67c
296  * ("net: avoid 32 x truesize under-estimation for tiny skbs")
297  * does not accidentally come back.
298  */
napi_get_frags_check(struct napi_struct * napi)299 void napi_get_frags_check(struct napi_struct *napi)
300 {
301 	struct sk_buff *skb;
302 
303 	local_bh_disable();
304 	skb = napi_get_frags(napi);
305 	WARN_ON_ONCE(!NAPI_HAS_SMALL_PAGE_FRAG && skb && skb->head_frag);
306 	napi_free_frags(napi);
307 	local_bh_enable();
308 }
309 
__napi_alloc_frag_align(unsigned int fragsz,unsigned int align_mask)310 void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
311 {
312 	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
313 	void *data;
314 
315 	fragsz = SKB_DATA_ALIGN(fragsz);
316 
317 	local_lock_nested_bh(&napi_alloc_cache.bh_lock);
318 	data = __page_frag_alloc_align(&nc->page, fragsz,
319 				       GFP_ATOMIC | __GFP_NOWARN, align_mask);
320 	local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
321 	return data;
322 
323 }
324 EXPORT_SYMBOL(__napi_alloc_frag_align);
325 
__netdev_alloc_frag_align(unsigned int fragsz,unsigned int align_mask)326 void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
327 {
328 	void *data;
329 
330 	if (in_hardirq() || irqs_disabled()) {
331 		struct page_frag_cache *nc = this_cpu_ptr(&netdev_alloc_cache);
332 
333 		fragsz = SKB_DATA_ALIGN(fragsz);
334 		data = __page_frag_alloc_align(nc, fragsz,
335 					       GFP_ATOMIC | __GFP_NOWARN,
336 					       align_mask);
337 	} else {
338 		local_bh_disable();
339 		data = __napi_alloc_frag_align(fragsz, align_mask);
340 		local_bh_enable();
341 	}
342 	return data;
343 }
344 EXPORT_SYMBOL(__netdev_alloc_frag_align);
345 
napi_skb_cache_get(void)346 static struct sk_buff *napi_skb_cache_get(void)
347 {
348 	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
349 	struct sk_buff *skb;
350 
351 	local_lock_nested_bh(&napi_alloc_cache.bh_lock);
352 	if (unlikely(!nc->skb_count)) {
353 		nc->skb_count = kmem_cache_alloc_bulk(net_hotdata.skbuff_cache,
354 						      GFP_ATOMIC | __GFP_NOWARN,
355 						      NAPI_SKB_CACHE_BULK,
356 						      nc->skb_cache);
357 		if (unlikely(!nc->skb_count)) {
358 			local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
359 			return NULL;
360 		}
361 	}
362 
363 	skb = nc->skb_cache[--nc->skb_count];
364 	local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
365 	kasan_mempool_unpoison_object(skb, kmem_cache_size(net_hotdata.skbuff_cache));
366 
367 	return skb;
368 }
369 
__finalize_skb_around(struct sk_buff * skb,void * data,unsigned int size)370 static inline void __finalize_skb_around(struct sk_buff *skb, void *data,
371 					 unsigned int size)
372 {
373 	struct skb_shared_info *shinfo;
374 
375 	size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
376 
377 	/* Assumes caller memset cleared SKB */
378 	skb->truesize = SKB_TRUESIZE(size);
379 	refcount_set(&skb->users, 1);
380 	skb->head = data;
381 	skb->data = data;
382 	skb_reset_tail_pointer(skb);
383 	skb_set_end_offset(skb, size);
384 	skb->mac_header = (typeof(skb->mac_header))~0U;
385 	skb->transport_header = (typeof(skb->transport_header))~0U;
386 	skb->alloc_cpu = raw_smp_processor_id();
387 	/* make sure we initialize shinfo sequentially */
388 	shinfo = skb_shinfo(skb);
389 	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
390 	atomic_set(&shinfo->dataref, 1);
391 
392 	skb_set_kcov_handle(skb, kcov_common_handle());
393 }
394 
__slab_build_skb(struct sk_buff * skb,void * data,unsigned int * size)395 static inline void *__slab_build_skb(struct sk_buff *skb, void *data,
396 				     unsigned int *size)
397 {
398 	void *resized;
399 
400 	/* Must find the allocation size (and grow it to match). */
401 	*size = ksize(data);
402 	/* krealloc() will immediately return "data" when
403 	 * "ksize(data)" is requested: it is the existing upper
404 	 * bounds. As a result, GFP_ATOMIC will be ignored. Note
405 	 * that this "new" pointer needs to be passed back to the
406 	 * caller for use so the __alloc_size hinting will be
407 	 * tracked correctly.
408 	 */
409 	resized = krealloc(data, *size, GFP_ATOMIC);
410 	WARN_ON_ONCE(resized != data);
411 	return resized;
412 }
413 
414 /* build_skb() variant which can operate on slab buffers.
415  * Note that this should be used sparingly as slab buffers
416  * cannot be combined efficiently by GRO!
417  */
slab_build_skb(void * data)418 struct sk_buff *slab_build_skb(void *data)
419 {
420 	struct sk_buff *skb;
421 	unsigned int size;
422 
423 	skb = kmem_cache_alloc(net_hotdata.skbuff_cache,
424 			       GFP_ATOMIC | __GFP_NOWARN);
425 	if (unlikely(!skb))
426 		return NULL;
427 
428 	memset(skb, 0, offsetof(struct sk_buff, tail));
429 	data = __slab_build_skb(skb, data, &size);
430 	__finalize_skb_around(skb, data, size);
431 
432 	return skb;
433 }
434 EXPORT_SYMBOL(slab_build_skb);
435 
436 /* Caller must provide SKB that is memset cleared */
__build_skb_around(struct sk_buff * skb,void * data,unsigned int frag_size)437 static void __build_skb_around(struct sk_buff *skb, void *data,
438 			       unsigned int frag_size)
439 {
440 	unsigned int size = frag_size;
441 
442 	/* frag_size == 0 is considered deprecated now. Callers
443 	 * using slab buffer should use slab_build_skb() instead.
444 	 */
445 	if (WARN_ONCE(size == 0, "Use slab_build_skb() instead"))
446 		data = __slab_build_skb(skb, data, &size);
447 
448 	__finalize_skb_around(skb, data, size);
449 }
450 
451 /**
452  * __build_skb - build a network buffer
453  * @data: data buffer provided by caller
454  * @frag_size: size of data (must not be 0)
455  *
456  * Allocate a new &sk_buff. Caller provides space holding head and
457  * skb_shared_info. @data must have been allocated from the page
458  * allocator or vmalloc(). (A @frag_size of 0 to indicate a kmalloc()
459  * allocation is deprecated, and callers should use slab_build_skb()
460  * instead.)
461  * The return is the new skb buffer.
462  * On a failure the return is %NULL, and @data is not freed.
463  * Notes :
464  *  Before IO, driver allocates only data buffer where NIC put incoming frame
465  *  Driver should add room at head (NET_SKB_PAD) and
466  *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
467  *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
468  *  before giving packet to stack.
469  *  RX rings only contains data buffers, not full skbs.
470  */
__build_skb(void * data,unsigned int frag_size)471 struct sk_buff *__build_skb(void *data, unsigned int frag_size)
472 {
473 	struct sk_buff *skb;
474 
475 	skb = kmem_cache_alloc(net_hotdata.skbuff_cache,
476 			       GFP_ATOMIC | __GFP_NOWARN);
477 	if (unlikely(!skb))
478 		return NULL;
479 
480 	memset(skb, 0, offsetof(struct sk_buff, tail));
481 	__build_skb_around(skb, data, frag_size);
482 
483 	return skb;
484 }
485 
486 /* build_skb() is wrapper over __build_skb(), that specifically
487  * takes care of skb->head and skb->pfmemalloc
488  */
build_skb(void * data,unsigned int frag_size)489 struct sk_buff *build_skb(void *data, unsigned int frag_size)
490 {
491 	struct sk_buff *skb = __build_skb(data, frag_size);
492 
493 	if (likely(skb && frag_size)) {
494 		skb->head_frag = 1;
495 		skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
496 	}
497 	return skb;
498 }
499 EXPORT_SYMBOL(build_skb);
500 
501 /**
502  * build_skb_around - build a network buffer around provided skb
503  * @skb: sk_buff provide by caller, must be memset cleared
504  * @data: data buffer provided by caller
505  * @frag_size: size of data
506  */
build_skb_around(struct sk_buff * skb,void * data,unsigned int frag_size)507 struct sk_buff *build_skb_around(struct sk_buff *skb,
508 				 void *data, unsigned int frag_size)
509 {
510 	if (unlikely(!skb))
511 		return NULL;
512 
513 	__build_skb_around(skb, data, frag_size);
514 
515 	if (frag_size) {
516 		skb->head_frag = 1;
517 		skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
518 	}
519 	return skb;
520 }
521 EXPORT_SYMBOL(build_skb_around);
522 
523 /**
524  * __napi_build_skb - build a network buffer
525  * @data: data buffer provided by caller
526  * @frag_size: size of data
527  *
528  * Version of __build_skb() that uses NAPI percpu caches to obtain
529  * skbuff_head instead of inplace allocation.
530  *
531  * Returns a new &sk_buff on success, %NULL on allocation failure.
532  */
__napi_build_skb(void * data,unsigned int frag_size)533 static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
534 {
535 	struct sk_buff *skb;
536 
537 	skb = napi_skb_cache_get();
538 	if (unlikely(!skb))
539 		return NULL;
540 
541 	memset(skb, 0, offsetof(struct sk_buff, tail));
542 	__build_skb_around(skb, data, frag_size);
543 
544 	return skb;
545 }
546 
547 /**
548  * napi_build_skb - build a network buffer
549  * @data: data buffer provided by caller
550  * @frag_size: size of data
551  *
552  * Version of __napi_build_skb() that takes care of skb->head_frag
553  * and skb->pfmemalloc when the data is a page or page fragment.
554  *
555  * Returns a new &sk_buff on success, %NULL on allocation failure.
556  */
napi_build_skb(void * data,unsigned int frag_size)557 struct sk_buff *napi_build_skb(void *data, unsigned int frag_size)
558 {
559 	struct sk_buff *skb = __napi_build_skb(data, frag_size);
560 
561 	if (likely(skb) && frag_size) {
562 		skb->head_frag = 1;
563 		skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
564 	}
565 
566 	return skb;
567 }
568 EXPORT_SYMBOL(napi_build_skb);
569 
570 /*
571  * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
572  * the caller if emergency pfmemalloc reserves are being used. If it is and
573  * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
574  * may be used. Otherwise, the packet data may be discarded until enough
575  * memory is free
576  */
kmalloc_reserve(unsigned int * size,gfp_t flags,int node,bool * pfmemalloc)577 static void *kmalloc_reserve(unsigned int *size, gfp_t flags, int node,
578 			     bool *pfmemalloc)
579 {
580 	bool ret_pfmemalloc = false;
581 	size_t obj_size;
582 	void *obj;
583 
584 	obj_size = SKB_HEAD_ALIGN(*size);
585 	if (obj_size <= SKB_SMALL_HEAD_CACHE_SIZE &&
586 	    !(flags & KMALLOC_NOT_NORMAL_BITS)) {
587 		obj = kmem_cache_alloc_node(net_hotdata.skb_small_head_cache,
588 				flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
589 				node);
590 		*size = SKB_SMALL_HEAD_CACHE_SIZE;
591 		if (obj || !(gfp_pfmemalloc_allowed(flags)))
592 			goto out;
593 		/* Try again but now we are using pfmemalloc reserves */
594 		ret_pfmemalloc = true;
595 		obj = kmem_cache_alloc_node(net_hotdata.skb_small_head_cache, flags, node);
596 		goto out;
597 	}
598 
599 	obj_size = kmalloc_size_roundup(obj_size);
600 	/* The following cast might truncate high-order bits of obj_size, this
601 	 * is harmless because kmalloc(obj_size >= 2^32) will fail anyway.
602 	 */
603 	*size = (unsigned int)obj_size;
604 
605 	/*
606 	 * Try a regular allocation, when that fails and we're not entitled
607 	 * to the reserves, fail.
608 	 */
609 	obj = kmalloc_node_track_caller(obj_size,
610 					flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
611 					node);
612 	if (obj || !(gfp_pfmemalloc_allowed(flags)))
613 		goto out;
614 
615 	/* Try again but now we are using pfmemalloc reserves */
616 	ret_pfmemalloc = true;
617 	obj = kmalloc_node_track_caller(obj_size, flags, node);
618 
619 out:
620 	if (pfmemalloc)
621 		*pfmemalloc = ret_pfmemalloc;
622 
623 	return obj;
624 }
625 
626 /* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
627  *	'private' fields and also do memory statistics to find all the
628  *	[BEEP] leaks.
629  *
630  */
631 
632 /**
633  *	__alloc_skb	-	allocate a network buffer
634  *	@size: size to allocate
635  *	@gfp_mask: allocation mask
636  *	@flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
637  *		instead of head cache and allocate a cloned (child) skb.
638  *		If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
639  *		allocations in case the data is required for writeback
640  *	@node: numa node to allocate memory on
641  *
642  *	Allocate a new &sk_buff. The returned buffer has no headroom and a
643  *	tail room of at least size bytes. The object has a reference count
644  *	of one. The return is the buffer. On a failure the return is %NULL.
645  *
646  *	Buffers may only be allocated from interrupts using a @gfp_mask of
647  *	%GFP_ATOMIC.
648  */
__alloc_skb(unsigned int size,gfp_t gfp_mask,int flags,int node)649 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
650 			    int flags, int node)
651 {
652 	struct kmem_cache *cache;
653 	struct sk_buff *skb;
654 	bool pfmemalloc;
655 	u8 *data;
656 
657 	cache = (flags & SKB_ALLOC_FCLONE)
658 		? net_hotdata.skbuff_fclone_cache : net_hotdata.skbuff_cache;
659 
660 	if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
661 		gfp_mask |= __GFP_MEMALLOC;
662 
663 	/* Get the HEAD */
664 	if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
665 	    likely(node == NUMA_NO_NODE || node == numa_mem_id()))
666 		skb = napi_skb_cache_get();
667 	else
668 		skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
669 	if (unlikely(!skb))
670 		return NULL;
671 	prefetchw(skb);
672 
673 	/* We do our best to align skb_shared_info on a separate cache
674 	 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
675 	 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
676 	 * Both skb->head and skb_shared_info are cache line aligned.
677 	 */
678 	data = kmalloc_reserve(&size, gfp_mask, node, &pfmemalloc);
679 	if (unlikely(!data))
680 		goto nodata;
681 	/* kmalloc_size_roundup() might give us more room than requested.
682 	 * Put skb_shared_info exactly at the end of allocated zone,
683 	 * to allow max possible filling before reallocation.
684 	 */
685 	prefetchw(data + SKB_WITH_OVERHEAD(size));
686 
687 	/*
688 	 * Only clear those fields we need to clear, not those that we will
689 	 * actually initialise below. Hence, don't put any more fields after
690 	 * the tail pointer in struct sk_buff!
691 	 */
692 	memset(skb, 0, offsetof(struct sk_buff, tail));
693 	__build_skb_around(skb, data, size);
694 	skb->pfmemalloc = pfmemalloc;
695 
696 	if (flags & SKB_ALLOC_FCLONE) {
697 		struct sk_buff_fclones *fclones;
698 
699 		fclones = container_of(skb, struct sk_buff_fclones, skb1);
700 
701 		skb->fclone = SKB_FCLONE_ORIG;
702 		refcount_set(&fclones->fclone_ref, 1);
703 	}
704 
705 	return skb;
706 
707 nodata:
708 	kmem_cache_free(cache, skb);
709 	return NULL;
710 }
711 EXPORT_SYMBOL(__alloc_skb);
712 
713 /**
714  *	__netdev_alloc_skb - allocate an skbuff for rx on a specific device
715  *	@dev: network device to receive on
716  *	@len: length to allocate
717  *	@gfp_mask: get_free_pages mask, passed to alloc_skb
718  *
719  *	Allocate a new &sk_buff and assign it a usage count of one. The
720  *	buffer has NET_SKB_PAD headroom built in. Users should allocate
721  *	the headroom they think they need without accounting for the
722  *	built in space. The built in space is used for optimisations.
723  *
724  *	%NULL is returned if there is no free memory.
725  */
__netdev_alloc_skb(struct net_device * dev,unsigned int len,gfp_t gfp_mask)726 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
727 				   gfp_t gfp_mask)
728 {
729 	struct page_frag_cache *nc;
730 	struct sk_buff *skb;
731 	bool pfmemalloc;
732 	void *data;
733 
734 	len += NET_SKB_PAD;
735 
736 	/* If requested length is either too small or too big,
737 	 * we use kmalloc() for skb->head allocation.
738 	 */
739 	if (len <= SKB_WITH_OVERHEAD(1024) ||
740 	    len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
741 	    (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
742 		skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
743 		if (!skb)
744 			goto skb_fail;
745 		goto skb_success;
746 	}
747 
748 	len = SKB_HEAD_ALIGN(len);
749 
750 	if (sk_memalloc_socks())
751 		gfp_mask |= __GFP_MEMALLOC;
752 
753 	if (in_hardirq() || irqs_disabled()) {
754 		nc = this_cpu_ptr(&netdev_alloc_cache);
755 		data = page_frag_alloc(nc, len, gfp_mask);
756 		pfmemalloc = nc->pfmemalloc;
757 	} else {
758 		local_bh_disable();
759 		local_lock_nested_bh(&napi_alloc_cache.bh_lock);
760 
761 		nc = this_cpu_ptr(&napi_alloc_cache.page);
762 		data = page_frag_alloc(nc, len, gfp_mask);
763 		pfmemalloc = nc->pfmemalloc;
764 
765 		local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
766 		local_bh_enable();
767 	}
768 
769 	if (unlikely(!data))
770 		return NULL;
771 
772 	skb = __build_skb(data, len);
773 	if (unlikely(!skb)) {
774 		skb_free_frag(data);
775 		return NULL;
776 	}
777 
778 	if (pfmemalloc)
779 		skb->pfmemalloc = 1;
780 	skb->head_frag = 1;
781 
782 skb_success:
783 	skb_reserve(skb, NET_SKB_PAD);
784 	skb->dev = dev;
785 
786 skb_fail:
787 	return skb;
788 }
789 EXPORT_SYMBOL(__netdev_alloc_skb);
790 
791 /**
792  *	napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
793  *	@napi: napi instance this buffer was allocated for
794  *	@len: length to allocate
795  *
796  *	Allocate a new sk_buff for use in NAPI receive.  This buffer will
797  *	attempt to allocate the head from a special reserved region used
798  *	only for NAPI Rx allocation.  By doing this we can save several
799  *	CPU cycles by avoiding having to disable and re-enable IRQs.
800  *
801  *	%NULL is returned if there is no free memory.
802  */
napi_alloc_skb(struct napi_struct * napi,unsigned int len)803 struct sk_buff *napi_alloc_skb(struct napi_struct *napi, unsigned int len)
804 {
805 	gfp_t gfp_mask = GFP_ATOMIC | __GFP_NOWARN;
806 	struct napi_alloc_cache *nc;
807 	struct sk_buff *skb;
808 	bool pfmemalloc;
809 	void *data;
810 
811 	DEBUG_NET_WARN_ON_ONCE(!in_softirq());
812 	len += NET_SKB_PAD + NET_IP_ALIGN;
813 
814 	/* If requested length is either too small or too big,
815 	 * we use kmalloc() for skb->head allocation.
816 	 * When the small frag allocator is available, prefer it over kmalloc
817 	 * for small fragments
818 	 */
819 	if ((!NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) ||
820 	    len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
821 	    (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
822 		skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX | SKB_ALLOC_NAPI,
823 				  NUMA_NO_NODE);
824 		if (!skb)
825 			goto skb_fail;
826 		goto skb_success;
827 	}
828 
829 	if (sk_memalloc_socks())
830 		gfp_mask |= __GFP_MEMALLOC;
831 
832 	local_lock_nested_bh(&napi_alloc_cache.bh_lock);
833 	nc = this_cpu_ptr(&napi_alloc_cache);
834 	if (NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) {
835 		/* we are artificially inflating the allocation size, but
836 		 * that is not as bad as it may look like, as:
837 		 * - 'len' less than GRO_MAX_HEAD makes little sense
838 		 * - On most systems, larger 'len' values lead to fragment
839 		 *   size above 512 bytes
840 		 * - kmalloc would use the kmalloc-1k slab for such values
841 		 * - Builds with smaller GRO_MAX_HEAD will very likely do
842 		 *   little networking, as that implies no WiFi and no
843 		 *   tunnels support, and 32 bits arches.
844 		 */
845 		len = SZ_1K;
846 
847 		data = page_frag_alloc_1k(&nc->page_small, gfp_mask);
848 		pfmemalloc = NAPI_SMALL_PAGE_PFMEMALLOC(nc->page_small);
849 	} else {
850 		len = SKB_HEAD_ALIGN(len);
851 
852 		data = page_frag_alloc(&nc->page, len, gfp_mask);
853 		pfmemalloc = nc->page.pfmemalloc;
854 	}
855 	local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
856 
857 	if (unlikely(!data))
858 		return NULL;
859 
860 	skb = __napi_build_skb(data, len);
861 	if (unlikely(!skb)) {
862 		skb_free_frag(data);
863 		return NULL;
864 	}
865 
866 	if (pfmemalloc)
867 		skb->pfmemalloc = 1;
868 	skb->head_frag = 1;
869 
870 skb_success:
871 	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
872 	skb->dev = napi->dev;
873 
874 skb_fail:
875 	return skb;
876 }
877 EXPORT_SYMBOL(napi_alloc_skb);
878 
skb_add_rx_frag_netmem(struct sk_buff * skb,int i,netmem_ref netmem,int off,int size,unsigned int truesize)879 void skb_add_rx_frag_netmem(struct sk_buff *skb, int i, netmem_ref netmem,
880 			    int off, int size, unsigned int truesize)
881 {
882 	DEBUG_NET_WARN_ON_ONCE(size > truesize);
883 
884 	skb_fill_netmem_desc(skb, i, netmem, off, size);
885 	skb->len += size;
886 	skb->data_len += size;
887 	skb->truesize += truesize;
888 }
889 EXPORT_SYMBOL(skb_add_rx_frag_netmem);
890 
skb_coalesce_rx_frag(struct sk_buff * skb,int i,int size,unsigned int truesize)891 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
892 			  unsigned int truesize)
893 {
894 	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
895 
896 	DEBUG_NET_WARN_ON_ONCE(size > truesize);
897 
898 	skb_frag_size_add(frag, size);
899 	skb->len += size;
900 	skb->data_len += size;
901 	skb->truesize += truesize;
902 }
903 EXPORT_SYMBOL(skb_coalesce_rx_frag);
904 
skb_drop_list(struct sk_buff ** listp)905 static void skb_drop_list(struct sk_buff **listp)
906 {
907 	kfree_skb_list(*listp);
908 	*listp = NULL;
909 }
910 
skb_drop_fraglist(struct sk_buff * skb)911 static inline void skb_drop_fraglist(struct sk_buff *skb)
912 {
913 	skb_drop_list(&skb_shinfo(skb)->frag_list);
914 }
915 
skb_clone_fraglist(struct sk_buff * skb)916 static void skb_clone_fraglist(struct sk_buff *skb)
917 {
918 	struct sk_buff *list;
919 
920 	skb_walk_frags(skb, list)
921 		skb_get(list);
922 }
923 
is_pp_netmem(netmem_ref netmem)924 static bool is_pp_netmem(netmem_ref netmem)
925 {
926 	return (netmem_get_pp_magic(netmem) & ~0x3UL) == PP_SIGNATURE;
927 }
928 
skb_pp_cow_data(struct page_pool * pool,struct sk_buff ** pskb,unsigned int headroom)929 int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
930 		    unsigned int headroom)
931 {
932 #if IS_ENABLED(CONFIG_PAGE_POOL)
933 	u32 size, truesize, len, max_head_size, off;
934 	struct sk_buff *skb = *pskb, *nskb;
935 	int err, i, head_off;
936 	void *data;
937 
938 	/* XDP does not support fraglist so we need to linearize
939 	 * the skb.
940 	 */
941 	if (skb_has_frag_list(skb))
942 		return -EOPNOTSUPP;
943 
944 	max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - headroom);
945 	if (skb->len > max_head_size + MAX_SKB_FRAGS * PAGE_SIZE)
946 		return -ENOMEM;
947 
948 	size = min_t(u32, skb->len, max_head_size);
949 	truesize = SKB_HEAD_ALIGN(size) + headroom;
950 	data = page_pool_dev_alloc_va(pool, &truesize);
951 	if (!data)
952 		return -ENOMEM;
953 
954 	nskb = napi_build_skb(data, truesize);
955 	if (!nskb) {
956 		page_pool_free_va(pool, data, true);
957 		return -ENOMEM;
958 	}
959 
960 	skb_reserve(nskb, headroom);
961 	skb_copy_header(nskb, skb);
962 	skb_mark_for_recycle(nskb);
963 
964 	err = skb_copy_bits(skb, 0, nskb->data, size);
965 	if (err) {
966 		consume_skb(nskb);
967 		return err;
968 	}
969 	skb_put(nskb, size);
970 
971 	head_off = skb_headroom(nskb) - skb_headroom(skb);
972 	skb_headers_offset_update(nskb, head_off);
973 
974 	off = size;
975 	len = skb->len - off;
976 	for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
977 		struct page *page;
978 		u32 page_off;
979 
980 		size = min_t(u32, len, PAGE_SIZE);
981 		truesize = size;
982 
983 		page = page_pool_dev_alloc(pool, &page_off, &truesize);
984 		if (!page) {
985 			consume_skb(nskb);
986 			return -ENOMEM;
987 		}
988 
989 		skb_add_rx_frag(nskb, i, page, page_off, size, truesize);
990 		err = skb_copy_bits(skb, off, page_address(page) + page_off,
991 				    size);
992 		if (err) {
993 			consume_skb(nskb);
994 			return err;
995 		}
996 
997 		len -= size;
998 		off += size;
999 	}
1000 
1001 	consume_skb(skb);
1002 	*pskb = nskb;
1003 
1004 	return 0;
1005 #else
1006 	return -EOPNOTSUPP;
1007 #endif
1008 }
1009 EXPORT_SYMBOL(skb_pp_cow_data);
1010 
skb_cow_data_for_xdp(struct page_pool * pool,struct sk_buff ** pskb,struct bpf_prog * prog)1011 int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
1012 			 struct bpf_prog *prog)
1013 {
1014 	if (!prog->aux->xdp_has_frags)
1015 		return -EINVAL;
1016 
1017 	return skb_pp_cow_data(pool, pskb, XDP_PACKET_HEADROOM);
1018 }
1019 EXPORT_SYMBOL(skb_cow_data_for_xdp);
1020 
1021 #if IS_ENABLED(CONFIG_PAGE_POOL)
napi_pp_put_page(netmem_ref netmem)1022 bool napi_pp_put_page(netmem_ref netmem)
1023 {
1024 	netmem = netmem_compound_head(netmem);
1025 
1026 	/* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
1027 	 * in order to preserve any existing bits, such as bit 0 for the
1028 	 * head page of compound page and bit 1 for pfmemalloc page, so
1029 	 * mask those bits for freeing side when doing below checking,
1030 	 * and page_is_pfmemalloc() is checked in __page_pool_put_page()
1031 	 * to avoid recycling the pfmemalloc page.
1032 	 */
1033 	if (unlikely(!is_pp_netmem(netmem)))
1034 		return false;
1035 
1036 	page_pool_put_full_netmem(netmem_get_pp(netmem), netmem, false);
1037 
1038 	return true;
1039 }
1040 EXPORT_SYMBOL(napi_pp_put_page);
1041 #endif
1042 
skb_pp_recycle(struct sk_buff * skb,void * data)1043 static bool skb_pp_recycle(struct sk_buff *skb, void *data)
1044 {
1045 	if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
1046 		return false;
1047 	return napi_pp_put_page(page_to_netmem(virt_to_page(data)));
1048 }
1049 
1050 /**
1051  * skb_pp_frag_ref() - Increase fragment references of a page pool aware skb
1052  * @skb:	page pool aware skb
1053  *
1054  * Increase the fragment reference count (pp_ref_count) of a skb. This is
1055  * intended to gain fragment references only for page pool aware skbs,
1056  * i.e. when skb->pp_recycle is true, and not for fragments in a
1057  * non-pp-recycling skb. It has a fallback to increase references on normal
1058  * pages, as page pool aware skbs may also have normal page fragments.
1059  */
skb_pp_frag_ref(struct sk_buff * skb)1060 static int skb_pp_frag_ref(struct sk_buff *skb)
1061 {
1062 	struct skb_shared_info *shinfo;
1063 	netmem_ref head_netmem;
1064 	int i;
1065 
1066 	if (!skb->pp_recycle)
1067 		return -EINVAL;
1068 
1069 	shinfo = skb_shinfo(skb);
1070 
1071 	for (i = 0; i < shinfo->nr_frags; i++) {
1072 		head_netmem = netmem_compound_head(shinfo->frags[i].netmem);
1073 		if (likely(is_pp_netmem(head_netmem)))
1074 			page_pool_ref_netmem(head_netmem);
1075 		else
1076 			page_ref_inc(netmem_to_page(head_netmem));
1077 	}
1078 	return 0;
1079 }
1080 
skb_kfree_head(void * head,unsigned int end_offset)1081 static void skb_kfree_head(void *head, unsigned int end_offset)
1082 {
1083 	if (end_offset == SKB_SMALL_HEAD_HEADROOM)
1084 		kmem_cache_free(net_hotdata.skb_small_head_cache, head);
1085 	else
1086 		kfree(head);
1087 }
1088 
skb_free_head(struct sk_buff * skb)1089 static void skb_free_head(struct sk_buff *skb)
1090 {
1091 	unsigned char *head = skb->head;
1092 
1093 	if (skb->head_frag) {
1094 		if (skb_pp_recycle(skb, head))
1095 			return;
1096 		skb_free_frag(head);
1097 	} else {
1098 		skb_kfree_head(head, skb_end_offset(skb));
1099 	}
1100 }
1101 
skb_release_data(struct sk_buff * skb,enum skb_drop_reason reason)1102 static void skb_release_data(struct sk_buff *skb, enum skb_drop_reason reason)
1103 {
1104 	struct skb_shared_info *shinfo = skb_shinfo(skb);
1105 	int i;
1106 
1107 	if (!skb_data_unref(skb, shinfo))
1108 		goto exit;
1109 
1110 	if (skb_zcopy(skb)) {
1111 		bool skip_unref = shinfo->flags & SKBFL_MANAGED_FRAG_REFS;
1112 
1113 		skb_zcopy_clear(skb, true);
1114 		if (skip_unref)
1115 			goto free_head;
1116 	}
1117 
1118 	for (i = 0; i < shinfo->nr_frags; i++)
1119 		__skb_frag_unref(&shinfo->frags[i], skb->pp_recycle);
1120 
1121 free_head:
1122 	if (shinfo->frag_list)
1123 		kfree_skb_list_reason(shinfo->frag_list, reason);
1124 
1125 	skb_free_head(skb);
1126 exit:
1127 	/* When we clone an SKB we copy the reycling bit. The pp_recycle
1128 	 * bit is only set on the head though, so in order to avoid races
1129 	 * while trying to recycle fragments on __skb_frag_unref() we need
1130 	 * to make one SKB responsible for triggering the recycle path.
1131 	 * So disable the recycling bit if an SKB is cloned and we have
1132 	 * additional references to the fragmented part of the SKB.
1133 	 * Eventually the last SKB will have the recycling bit set and it's
1134 	 * dataref set to 0, which will trigger the recycling
1135 	 */
1136 	skb->pp_recycle = 0;
1137 }
1138 
1139 /*
1140  *	Free an skbuff by memory without cleaning the state.
1141  */
kfree_skbmem(struct sk_buff * skb)1142 static void kfree_skbmem(struct sk_buff *skb)
1143 {
1144 	struct sk_buff_fclones *fclones;
1145 
1146 	switch (skb->fclone) {
1147 	case SKB_FCLONE_UNAVAILABLE:
1148 		kmem_cache_free(net_hotdata.skbuff_cache, skb);
1149 		return;
1150 
1151 	case SKB_FCLONE_ORIG:
1152 		fclones = container_of(skb, struct sk_buff_fclones, skb1);
1153 
1154 		/* We usually free the clone (TX completion) before original skb
1155 		 * This test would have no chance to be true for the clone,
1156 		 * while here, branch prediction will be good.
1157 		 */
1158 		if (refcount_read(&fclones->fclone_ref) == 1)
1159 			goto fastpath;
1160 		break;
1161 
1162 	default: /* SKB_FCLONE_CLONE */
1163 		fclones = container_of(skb, struct sk_buff_fclones, skb2);
1164 		break;
1165 	}
1166 	if (!refcount_dec_and_test(&fclones->fclone_ref))
1167 		return;
1168 fastpath:
1169 	kmem_cache_free(net_hotdata.skbuff_fclone_cache, fclones);
1170 }
1171 
skb_release_head_state(struct sk_buff * skb)1172 void skb_release_head_state(struct sk_buff *skb)
1173 {
1174 	skb_dst_drop(skb);
1175 	if (skb->destructor) {
1176 		DEBUG_NET_WARN_ON_ONCE(in_hardirq());
1177 		skb->destructor(skb);
1178 	}
1179 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
1180 	nf_conntrack_put(skb_nfct(skb));
1181 #endif
1182 	skb_ext_put(skb);
1183 }
1184 
1185 /* Free everything but the sk_buff shell. */
skb_release_all(struct sk_buff * skb,enum skb_drop_reason reason)1186 static void skb_release_all(struct sk_buff *skb, enum skb_drop_reason reason)
1187 {
1188 	skb_release_head_state(skb);
1189 	if (likely(skb->head))
1190 		skb_release_data(skb, reason);
1191 }
1192 
1193 /**
1194  *	__kfree_skb - private function
1195  *	@skb: buffer
1196  *
1197  *	Free an sk_buff. Release anything attached to the buffer.
1198  *	Clean the state. This is an internal helper function. Users should
1199  *	always call kfree_skb
1200  */
1201 
__kfree_skb(struct sk_buff * skb)1202 void __kfree_skb(struct sk_buff *skb)
1203 {
1204 	skb_release_all(skb, SKB_DROP_REASON_NOT_SPECIFIED);
1205 	kfree_skbmem(skb);
1206 }
1207 EXPORT_SYMBOL(__kfree_skb);
1208 
1209 static __always_inline
__sk_skb_reason_drop(struct sock * sk,struct sk_buff * skb,enum skb_drop_reason reason)1210 bool __sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb,
1211 			  enum skb_drop_reason reason)
1212 {
1213 	if (unlikely(!skb_unref(skb)))
1214 		return false;
1215 
1216 	DEBUG_NET_WARN_ON_ONCE(reason == SKB_NOT_DROPPED_YET ||
1217 			       u32_get_bits(reason,
1218 					    SKB_DROP_REASON_SUBSYS_MASK) >=
1219 				SKB_DROP_REASON_SUBSYS_NUM);
1220 
1221 	if (reason == SKB_CONSUMED)
1222 		trace_consume_skb(skb, __builtin_return_address(0));
1223 	else
1224 		trace_kfree_skb(skb, __builtin_return_address(0), reason, sk);
1225 	return true;
1226 }
1227 
1228 /**
1229  *	sk_skb_reason_drop - free an sk_buff with special reason
1230  *	@sk: the socket to receive @skb, or NULL if not applicable
1231  *	@skb: buffer to free
1232  *	@reason: reason why this skb is dropped
1233  *
1234  *	Drop a reference to the buffer and free it if the usage count has hit
1235  *	zero. Meanwhile, pass the receiving socket and drop reason to
1236  *	'kfree_skb' tracepoint.
1237  */
1238 void __fix_address
sk_skb_reason_drop(struct sock * sk,struct sk_buff * skb,enum skb_drop_reason reason)1239 sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb, enum skb_drop_reason reason)
1240 {
1241 	if (__sk_skb_reason_drop(sk, skb, reason))
1242 		__kfree_skb(skb);
1243 }
1244 EXPORT_SYMBOL(sk_skb_reason_drop);
1245 
1246 #define KFREE_SKB_BULK_SIZE	16
1247 
1248 struct skb_free_array {
1249 	unsigned int skb_count;
1250 	void *skb_array[KFREE_SKB_BULK_SIZE];
1251 };
1252 
kfree_skb_add_bulk(struct sk_buff * skb,struct skb_free_array * sa,enum skb_drop_reason reason)1253 static void kfree_skb_add_bulk(struct sk_buff *skb,
1254 			       struct skb_free_array *sa,
1255 			       enum skb_drop_reason reason)
1256 {
1257 	/* if SKB is a clone, don't handle this case */
1258 	if (unlikely(skb->fclone != SKB_FCLONE_UNAVAILABLE)) {
1259 		__kfree_skb(skb);
1260 		return;
1261 	}
1262 
1263 	skb_release_all(skb, reason);
1264 	sa->skb_array[sa->skb_count++] = skb;
1265 
1266 	if (unlikely(sa->skb_count == KFREE_SKB_BULK_SIZE)) {
1267 		kmem_cache_free_bulk(net_hotdata.skbuff_cache, KFREE_SKB_BULK_SIZE,
1268 				     sa->skb_array);
1269 		sa->skb_count = 0;
1270 	}
1271 }
1272 
1273 void __fix_address
kfree_skb_list_reason(struct sk_buff * segs,enum skb_drop_reason reason)1274 kfree_skb_list_reason(struct sk_buff *segs, enum skb_drop_reason reason)
1275 {
1276 	struct skb_free_array sa;
1277 
1278 	sa.skb_count = 0;
1279 
1280 	while (segs) {
1281 		struct sk_buff *next = segs->next;
1282 
1283 		if (__sk_skb_reason_drop(NULL, segs, reason)) {
1284 			skb_poison_list(segs);
1285 			kfree_skb_add_bulk(segs, &sa, reason);
1286 		}
1287 
1288 		segs = next;
1289 	}
1290 
1291 	if (sa.skb_count)
1292 		kmem_cache_free_bulk(net_hotdata.skbuff_cache, sa.skb_count, sa.skb_array);
1293 }
1294 EXPORT_SYMBOL(kfree_skb_list_reason);
1295 
1296 /* Dump skb information and contents.
1297  *
1298  * Must only be called from net_ratelimit()-ed paths.
1299  *
1300  * Dumps whole packets if full_pkt, only headers otherwise.
1301  */
skb_dump(const char * level,const struct sk_buff * skb,bool full_pkt)1302 void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
1303 {
1304 	struct skb_shared_info *sh = skb_shinfo(skb);
1305 	struct net_device *dev = skb->dev;
1306 	struct sock *sk = skb->sk;
1307 	struct sk_buff *list_skb;
1308 	bool has_mac, has_trans;
1309 	int headroom, tailroom;
1310 	int i, len, seg_len;
1311 
1312 	if (full_pkt)
1313 		len = skb->len;
1314 	else
1315 		len = min_t(int, skb->len, MAX_HEADER + 128);
1316 
1317 	headroom = skb_headroom(skb);
1318 	tailroom = skb_tailroom(skb);
1319 
1320 	has_mac = skb_mac_header_was_set(skb);
1321 	has_trans = skb_transport_header_was_set(skb);
1322 
1323 	printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
1324 	       "mac=(%d,%d) mac_len=%u net=(%d,%d) trans=%d\n"
1325 	       "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
1326 	       "csum(0x%x start=%u offset=%u ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
1327 	       "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n"
1328 	       "priority=0x%x mark=0x%x alloc_cpu=%u vlan_all=0x%x\n"
1329 	       "encapsulation=%d inner(proto=0x%04x, mac=%u, net=%u, trans=%u)\n",
1330 	       level, skb->len, headroom, skb_headlen(skb), tailroom,
1331 	       has_mac ? skb->mac_header : -1,
1332 	       has_mac ? skb_mac_header_len(skb) : -1,
1333 	       skb->mac_len,
1334 	       skb->network_header,
1335 	       has_trans ? skb_network_header_len(skb) : -1,
1336 	       has_trans ? skb->transport_header : -1,
1337 	       sh->tx_flags, sh->nr_frags,
1338 	       sh->gso_size, sh->gso_type, sh->gso_segs,
1339 	       skb->csum, skb->csum_start, skb->csum_offset, skb->ip_summed,
1340 	       skb->csum_complete_sw, skb->csum_valid, skb->csum_level,
1341 	       skb->hash, skb->sw_hash, skb->l4_hash,
1342 	       ntohs(skb->protocol), skb->pkt_type, skb->skb_iif,
1343 	       skb->priority, skb->mark, skb->alloc_cpu, skb->vlan_all,
1344 	       skb->encapsulation, skb->inner_protocol, skb->inner_mac_header,
1345 	       skb->inner_network_header, skb->inner_transport_header);
1346 
1347 	if (dev)
1348 		printk("%sdev name=%s feat=%pNF\n",
1349 		       level, dev->name, &dev->features);
1350 	if (sk)
1351 		printk("%ssk family=%hu type=%u proto=%u\n",
1352 		       level, sk->sk_family, sk->sk_type, sk->sk_protocol);
1353 
1354 	if (full_pkt && headroom)
1355 		print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
1356 			       16, 1, skb->head, headroom, false);
1357 
1358 	seg_len = min_t(int, skb_headlen(skb), len);
1359 	if (seg_len)
1360 		print_hex_dump(level, "skb linear:   ", DUMP_PREFIX_OFFSET,
1361 			       16, 1, skb->data, seg_len, false);
1362 	len -= seg_len;
1363 
1364 	if (full_pkt && tailroom)
1365 		print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
1366 			       16, 1, skb_tail_pointer(skb), tailroom, false);
1367 
1368 	for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
1369 		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1370 		u32 p_off, p_len, copied;
1371 		struct page *p;
1372 		u8 *vaddr;
1373 
1374 		if (skb_frag_is_net_iov(frag)) {
1375 			printk("%sskb frag %d: not readable\n", level, i);
1376 			len -= skb_frag_size(frag);
1377 			if (!len)
1378 				break;
1379 			continue;
1380 		}
1381 
1382 		skb_frag_foreach_page(frag, skb_frag_off(frag),
1383 				      skb_frag_size(frag), p, p_off, p_len,
1384 				      copied) {
1385 			seg_len = min_t(int, p_len, len);
1386 			vaddr = kmap_atomic(p);
1387 			print_hex_dump(level, "skb frag:     ",
1388 				       DUMP_PREFIX_OFFSET,
1389 				       16, 1, vaddr + p_off, seg_len, false);
1390 			kunmap_atomic(vaddr);
1391 			len -= seg_len;
1392 			if (!len)
1393 				break;
1394 		}
1395 	}
1396 
1397 	if (full_pkt && skb_has_frag_list(skb)) {
1398 		printk("skb fraglist:\n");
1399 		skb_walk_frags(skb, list_skb)
1400 			skb_dump(level, list_skb, true);
1401 	}
1402 }
1403 EXPORT_SYMBOL(skb_dump);
1404 
1405 /**
1406  *	skb_tx_error - report an sk_buff xmit error
1407  *	@skb: buffer that triggered an error
1408  *
1409  *	Report xmit error if a device callback is tracking this skb.
1410  *	skb must be freed afterwards.
1411  */
skb_tx_error(struct sk_buff * skb)1412 void skb_tx_error(struct sk_buff *skb)
1413 {
1414 	if (skb) {
1415 		skb_zcopy_downgrade_managed(skb);
1416 		skb_zcopy_clear(skb, true);
1417 	}
1418 }
1419 EXPORT_SYMBOL(skb_tx_error);
1420 
1421 #ifdef CONFIG_TRACEPOINTS
1422 /**
1423  *	consume_skb - free an skbuff
1424  *	@skb: buffer to free
1425  *
1426  *	Drop a ref to the buffer and free it if the usage count has hit zero
1427  *	Functions identically to kfree_skb, but kfree_skb assumes that the frame
1428  *	is being dropped after a failure and notes that
1429  */
consume_skb(struct sk_buff * skb)1430 void consume_skb(struct sk_buff *skb)
1431 {
1432 	if (!skb_unref(skb))
1433 		return;
1434 
1435 	trace_consume_skb(skb, __builtin_return_address(0));
1436 	__kfree_skb(skb);
1437 }
1438 EXPORT_SYMBOL(consume_skb);
1439 #endif
1440 
1441 /**
1442  *	__consume_stateless_skb - free an skbuff, assuming it is stateless
1443  *	@skb: buffer to free
1444  *
1445  *	Alike consume_skb(), but this variant assumes that this is the last
1446  *	skb reference and all the head states have been already dropped
1447  */
__consume_stateless_skb(struct sk_buff * skb)1448 void __consume_stateless_skb(struct sk_buff *skb)
1449 {
1450 	trace_consume_skb(skb, __builtin_return_address(0));
1451 	skb_release_data(skb, SKB_CONSUMED);
1452 	kfree_skbmem(skb);
1453 }
1454 
napi_skb_cache_put(struct sk_buff * skb)1455 static void napi_skb_cache_put(struct sk_buff *skb)
1456 {
1457 	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
1458 	u32 i;
1459 
1460 	if (!kasan_mempool_poison_object(skb))
1461 		return;
1462 
1463 	local_lock_nested_bh(&napi_alloc_cache.bh_lock);
1464 	nc->skb_cache[nc->skb_count++] = skb;
1465 
1466 	if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
1467 		for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
1468 			kasan_mempool_unpoison_object(nc->skb_cache[i],
1469 						kmem_cache_size(net_hotdata.skbuff_cache));
1470 
1471 		kmem_cache_free_bulk(net_hotdata.skbuff_cache, NAPI_SKB_CACHE_HALF,
1472 				     nc->skb_cache + NAPI_SKB_CACHE_HALF);
1473 		nc->skb_count = NAPI_SKB_CACHE_HALF;
1474 	}
1475 	local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
1476 }
1477 
__napi_kfree_skb(struct sk_buff * skb,enum skb_drop_reason reason)1478 void __napi_kfree_skb(struct sk_buff *skb, enum skb_drop_reason reason)
1479 {
1480 	skb_release_all(skb, reason);
1481 	napi_skb_cache_put(skb);
1482 }
1483 
napi_skb_free_stolen_head(struct sk_buff * skb)1484 void napi_skb_free_stolen_head(struct sk_buff *skb)
1485 {
1486 	if (unlikely(skb->slow_gro)) {
1487 		nf_reset_ct(skb);
1488 		skb_dst_drop(skb);
1489 		skb_ext_put(skb);
1490 		skb_orphan(skb);
1491 		skb->slow_gro = 0;
1492 	}
1493 	napi_skb_cache_put(skb);
1494 }
1495 
napi_consume_skb(struct sk_buff * skb,int budget)1496 void napi_consume_skb(struct sk_buff *skb, int budget)
1497 {
1498 	/* Zero budget indicate non-NAPI context called us, like netpoll */
1499 	if (unlikely(!budget)) {
1500 		dev_consume_skb_any(skb);
1501 		return;
1502 	}
1503 
1504 	DEBUG_NET_WARN_ON_ONCE(!in_softirq());
1505 
1506 	if (!skb_unref(skb))
1507 		return;
1508 
1509 	/* if reaching here SKB is ready to free */
1510 	trace_consume_skb(skb, __builtin_return_address(0));
1511 
1512 	/* if SKB is a clone, don't handle this case */
1513 	if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
1514 		__kfree_skb(skb);
1515 		return;
1516 	}
1517 
1518 	skb_release_all(skb, SKB_CONSUMED);
1519 	napi_skb_cache_put(skb);
1520 }
1521 EXPORT_SYMBOL(napi_consume_skb);
1522 
1523 /* Make sure a field is contained by headers group */
1524 #define CHECK_SKB_FIELD(field) \
1525 	BUILD_BUG_ON(offsetof(struct sk_buff, field) !=		\
1526 		     offsetof(struct sk_buff, headers.field));	\
1527 
__copy_skb_header(struct sk_buff * new,const struct sk_buff * old)1528 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
1529 {
1530 	new->tstamp		= old->tstamp;
1531 	/* We do not copy old->sk */
1532 	new->dev		= old->dev;
1533 	memcpy(new->cb, old->cb, sizeof(old->cb));
1534 	skb_dst_copy(new, old);
1535 	__skb_ext_copy(new, old);
1536 	__nf_copy(new, old, false);
1537 
1538 	/* Note : this field could be in the headers group.
1539 	 * It is not yet because we do not want to have a 16 bit hole
1540 	 */
1541 	new->queue_mapping = old->queue_mapping;
1542 
1543 	memcpy(&new->headers, &old->headers, sizeof(new->headers));
1544 	CHECK_SKB_FIELD(protocol);
1545 	CHECK_SKB_FIELD(csum);
1546 	CHECK_SKB_FIELD(hash);
1547 	CHECK_SKB_FIELD(priority);
1548 	CHECK_SKB_FIELD(skb_iif);
1549 	CHECK_SKB_FIELD(vlan_proto);
1550 	CHECK_SKB_FIELD(vlan_tci);
1551 	CHECK_SKB_FIELD(transport_header);
1552 	CHECK_SKB_FIELD(network_header);
1553 	CHECK_SKB_FIELD(mac_header);
1554 	CHECK_SKB_FIELD(inner_protocol);
1555 	CHECK_SKB_FIELD(inner_transport_header);
1556 	CHECK_SKB_FIELD(inner_network_header);
1557 	CHECK_SKB_FIELD(inner_mac_header);
1558 	CHECK_SKB_FIELD(mark);
1559 #ifdef CONFIG_NETWORK_SECMARK
1560 	CHECK_SKB_FIELD(secmark);
1561 #endif
1562 #ifdef CONFIG_NET_RX_BUSY_POLL
1563 	CHECK_SKB_FIELD(napi_id);
1564 #endif
1565 	CHECK_SKB_FIELD(alloc_cpu);
1566 #ifdef CONFIG_XPS
1567 	CHECK_SKB_FIELD(sender_cpu);
1568 #endif
1569 #ifdef CONFIG_NET_SCHED
1570 	CHECK_SKB_FIELD(tc_index);
1571 #endif
1572 
1573 }
1574 
1575 /*
1576  * You should not add any new code to this function.  Add it to
1577  * __copy_skb_header above instead.
1578  */
__skb_clone(struct sk_buff * n,struct sk_buff * skb)1579 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
1580 {
1581 #define C(x) n->x = skb->x
1582 
1583 	n->next = n->prev = NULL;
1584 	n->sk = NULL;
1585 	__copy_skb_header(n, skb);
1586 
1587 	C(len);
1588 	C(data_len);
1589 	C(mac_len);
1590 	n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
1591 	n->cloned = 1;
1592 	n->nohdr = 0;
1593 	n->peeked = 0;
1594 	C(pfmemalloc);
1595 	C(pp_recycle);
1596 	n->destructor = NULL;
1597 	C(tail);
1598 	C(end);
1599 	C(head);
1600 	C(head_frag);
1601 	C(data);
1602 	C(truesize);
1603 	refcount_set(&n->users, 1);
1604 
1605 	atomic_inc(&(skb_shinfo(skb)->dataref));
1606 	skb->cloned = 1;
1607 
1608 	return n;
1609 #undef C
1610 }
1611 
1612 /**
1613  * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
1614  * @first: first sk_buff of the msg
1615  */
alloc_skb_for_msg(struct sk_buff * first)1616 struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
1617 {
1618 	struct sk_buff *n;
1619 
1620 	n = alloc_skb(0, GFP_ATOMIC);
1621 	if (!n)
1622 		return NULL;
1623 
1624 	n->len = first->len;
1625 	n->data_len = first->len;
1626 	n->truesize = first->truesize;
1627 
1628 	skb_shinfo(n)->frag_list = first;
1629 
1630 	__copy_skb_header(n, first);
1631 	n->destructor = NULL;
1632 
1633 	return n;
1634 }
1635 EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
1636 
1637 /**
1638  *	skb_morph	-	morph one skb into another
1639  *	@dst: the skb to receive the contents
1640  *	@src: the skb to supply the contents
1641  *
1642  *	This is identical to skb_clone except that the target skb is
1643  *	supplied by the user.
1644  *
1645  *	The target skb is returned upon exit.
1646  */
skb_morph(struct sk_buff * dst,struct sk_buff * src)1647 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
1648 {
1649 	skb_release_all(dst, SKB_CONSUMED);
1650 	return __skb_clone(dst, src);
1651 }
1652 EXPORT_SYMBOL_GPL(skb_morph);
1653 
mm_account_pinned_pages(struct mmpin * mmp,size_t size)1654 int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
1655 {
1656 	unsigned long max_pg, num_pg, new_pg, old_pg, rlim;
1657 	struct user_struct *user;
1658 
1659 	if (capable(CAP_IPC_LOCK) || !size)
1660 		return 0;
1661 
1662 	rlim = rlimit(RLIMIT_MEMLOCK);
1663 	if (rlim == RLIM_INFINITY)
1664 		return 0;
1665 
1666 	num_pg = (size >> PAGE_SHIFT) + 2;	/* worst case */
1667 	max_pg = rlim >> PAGE_SHIFT;
1668 	user = mmp->user ? : current_user();
1669 
1670 	old_pg = atomic_long_read(&user->locked_vm);
1671 	do {
1672 		new_pg = old_pg + num_pg;
1673 		if (new_pg > max_pg)
1674 			return -ENOBUFS;
1675 	} while (!atomic_long_try_cmpxchg(&user->locked_vm, &old_pg, new_pg));
1676 
1677 	if (!mmp->user) {
1678 		mmp->user = get_uid(user);
1679 		mmp->num_pg = num_pg;
1680 	} else {
1681 		mmp->num_pg += num_pg;
1682 	}
1683 
1684 	return 0;
1685 }
1686 EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
1687 
mm_unaccount_pinned_pages(struct mmpin * mmp)1688 void mm_unaccount_pinned_pages(struct mmpin *mmp)
1689 {
1690 	if (mmp->user) {
1691 		atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
1692 		free_uid(mmp->user);
1693 	}
1694 }
1695 EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
1696 
msg_zerocopy_alloc(struct sock * sk,size_t size)1697 static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
1698 {
1699 	struct ubuf_info_msgzc *uarg;
1700 	struct sk_buff *skb;
1701 
1702 	WARN_ON_ONCE(!in_task());
1703 
1704 	skb = sock_omalloc(sk, 0, GFP_KERNEL);
1705 	if (!skb)
1706 		return NULL;
1707 
1708 	BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
1709 	uarg = (void *)skb->cb;
1710 	uarg->mmp.user = NULL;
1711 
1712 	if (mm_account_pinned_pages(&uarg->mmp, size)) {
1713 		kfree_skb(skb);
1714 		return NULL;
1715 	}
1716 
1717 	uarg->ubuf.ops = &msg_zerocopy_ubuf_ops;
1718 	uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
1719 	uarg->len = 1;
1720 	uarg->bytelen = size;
1721 	uarg->zerocopy = 1;
1722 	uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
1723 	refcount_set(&uarg->ubuf.refcnt, 1);
1724 	sock_hold(sk);
1725 
1726 	return &uarg->ubuf;
1727 }
1728 
skb_from_uarg(struct ubuf_info_msgzc * uarg)1729 static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
1730 {
1731 	return container_of((void *)uarg, struct sk_buff, cb);
1732 }
1733 
msg_zerocopy_realloc(struct sock * sk,size_t size,struct ubuf_info * uarg)1734 struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
1735 				       struct ubuf_info *uarg)
1736 {
1737 	if (uarg) {
1738 		struct ubuf_info_msgzc *uarg_zc;
1739 		const u32 byte_limit = 1 << 19;		/* limit to a few TSO */
1740 		u32 bytelen, next;
1741 
1742 		/* there might be non MSG_ZEROCOPY users */
1743 		if (uarg->ops != &msg_zerocopy_ubuf_ops)
1744 			return NULL;
1745 
1746 		/* realloc only when socket is locked (TCP, UDP cork),
1747 		 * so uarg->len and sk_zckey access is serialized
1748 		 */
1749 		if (!sock_owned_by_user(sk)) {
1750 			WARN_ON_ONCE(1);
1751 			return NULL;
1752 		}
1753 
1754 		uarg_zc = uarg_to_msgzc(uarg);
1755 		bytelen = uarg_zc->bytelen + size;
1756 		if (uarg_zc->len == USHRT_MAX - 1 || bytelen > byte_limit) {
1757 			/* TCP can create new skb to attach new uarg */
1758 			if (sk->sk_type == SOCK_STREAM)
1759 				goto new_alloc;
1760 			return NULL;
1761 		}
1762 
1763 		next = (u32)atomic_read(&sk->sk_zckey);
1764 		if ((u32)(uarg_zc->id + uarg_zc->len) == next) {
1765 			if (mm_account_pinned_pages(&uarg_zc->mmp, size))
1766 				return NULL;
1767 			uarg_zc->len++;
1768 			uarg_zc->bytelen = bytelen;
1769 			atomic_set(&sk->sk_zckey, ++next);
1770 
1771 			/* no extra ref when appending to datagram (MSG_MORE) */
1772 			if (sk->sk_type == SOCK_STREAM)
1773 				net_zcopy_get(uarg);
1774 
1775 			return uarg;
1776 		}
1777 	}
1778 
1779 new_alloc:
1780 	return msg_zerocopy_alloc(sk, size);
1781 }
1782 EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
1783 
skb_zerocopy_notify_extend(struct sk_buff * skb,u32 lo,u16 len)1784 static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
1785 {
1786 	struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
1787 	u32 old_lo, old_hi;
1788 	u64 sum_len;
1789 
1790 	old_lo = serr->ee.ee_info;
1791 	old_hi = serr->ee.ee_data;
1792 	sum_len = old_hi - old_lo + 1ULL + len;
1793 
1794 	if (sum_len >= (1ULL << 32))
1795 		return false;
1796 
1797 	if (lo != old_hi + 1)
1798 		return false;
1799 
1800 	serr->ee.ee_data += len;
1801 	return true;
1802 }
1803 
__msg_zerocopy_callback(struct ubuf_info_msgzc * uarg)1804 static void __msg_zerocopy_callback(struct ubuf_info_msgzc *uarg)
1805 {
1806 	struct sk_buff *tail, *skb = skb_from_uarg(uarg);
1807 	struct sock_exterr_skb *serr;
1808 	struct sock *sk = skb->sk;
1809 	struct sk_buff_head *q;
1810 	unsigned long flags;
1811 	bool is_zerocopy;
1812 	u32 lo, hi;
1813 	u16 len;
1814 
1815 	mm_unaccount_pinned_pages(&uarg->mmp);
1816 
1817 	/* if !len, there was only 1 call, and it was aborted
1818 	 * so do not queue a completion notification
1819 	 */
1820 	if (!uarg->len || sock_flag(sk, SOCK_DEAD))
1821 		goto release;
1822 
1823 	len = uarg->len;
1824 	lo = uarg->id;
1825 	hi = uarg->id + len - 1;
1826 	is_zerocopy = uarg->zerocopy;
1827 
1828 	serr = SKB_EXT_ERR(skb);
1829 	memset(serr, 0, sizeof(*serr));
1830 	serr->ee.ee_errno = 0;
1831 	serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
1832 	serr->ee.ee_data = hi;
1833 	serr->ee.ee_info = lo;
1834 	if (!is_zerocopy)
1835 		serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
1836 
1837 	q = &sk->sk_error_queue;
1838 	spin_lock_irqsave(&q->lock, flags);
1839 	tail = skb_peek_tail(q);
1840 	if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
1841 	    !skb_zerocopy_notify_extend(tail, lo, len)) {
1842 		__skb_queue_tail(q, skb);
1843 		skb = NULL;
1844 	}
1845 	spin_unlock_irqrestore(&q->lock, flags);
1846 
1847 	sk_error_report(sk);
1848 
1849 release:
1850 	consume_skb(skb);
1851 	sock_put(sk);
1852 }
1853 
msg_zerocopy_complete(struct sk_buff * skb,struct ubuf_info * uarg,bool success)1854 static void msg_zerocopy_complete(struct sk_buff *skb, struct ubuf_info *uarg,
1855 				  bool success)
1856 {
1857 	struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
1858 
1859 	uarg_zc->zerocopy = uarg_zc->zerocopy & success;
1860 
1861 	if (refcount_dec_and_test(&uarg->refcnt))
1862 		__msg_zerocopy_callback(uarg_zc);
1863 }
1864 
msg_zerocopy_put_abort(struct ubuf_info * uarg,bool have_uref)1865 void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
1866 {
1867 	struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
1868 
1869 	atomic_dec(&sk->sk_zckey);
1870 	uarg_to_msgzc(uarg)->len--;
1871 
1872 	if (have_uref)
1873 		msg_zerocopy_complete(NULL, uarg, true);
1874 }
1875 EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
1876 
1877 const struct ubuf_info_ops msg_zerocopy_ubuf_ops = {
1878 	.complete = msg_zerocopy_complete,
1879 };
1880 EXPORT_SYMBOL_GPL(msg_zerocopy_ubuf_ops);
1881 
skb_zerocopy_iter_stream(struct sock * sk,struct sk_buff * skb,struct msghdr * msg,int len,struct ubuf_info * uarg)1882 int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
1883 			     struct msghdr *msg, int len,
1884 			     struct ubuf_info *uarg)
1885 {
1886 	int err, orig_len = skb->len;
1887 
1888 	if (uarg->ops->link_skb) {
1889 		err = uarg->ops->link_skb(skb, uarg);
1890 		if (err)
1891 			return err;
1892 	} else {
1893 		struct ubuf_info *orig_uarg = skb_zcopy(skb);
1894 
1895 		/* An skb can only point to one uarg. This edge case happens
1896 		 * when TCP appends to an skb, but zerocopy_realloc triggered
1897 		 * a new alloc.
1898 		 */
1899 		if (orig_uarg && uarg != orig_uarg)
1900 			return -EEXIST;
1901 	}
1902 
1903 	err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
1904 	if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
1905 		struct sock *save_sk = skb->sk;
1906 
1907 		/* Streams do not free skb on error. Reset to prev state. */
1908 		iov_iter_revert(&msg->msg_iter, skb->len - orig_len);
1909 		skb->sk = sk;
1910 		___pskb_trim(skb, orig_len);
1911 		skb->sk = save_sk;
1912 		return err;
1913 	}
1914 
1915 	skb_zcopy_set(skb, uarg, NULL);
1916 	return skb->len - orig_len;
1917 }
1918 EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
1919 
__skb_zcopy_downgrade_managed(struct sk_buff * skb)1920 void __skb_zcopy_downgrade_managed(struct sk_buff *skb)
1921 {
1922 	int i;
1923 
1924 	skb_shinfo(skb)->flags &= ~SKBFL_MANAGED_FRAG_REFS;
1925 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1926 		skb_frag_ref(skb, i);
1927 }
1928 EXPORT_SYMBOL_GPL(__skb_zcopy_downgrade_managed);
1929 
skb_zerocopy_clone(struct sk_buff * nskb,struct sk_buff * orig,gfp_t gfp_mask)1930 static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
1931 			      gfp_t gfp_mask)
1932 {
1933 	if (skb_zcopy(orig)) {
1934 		if (skb_zcopy(nskb)) {
1935 			/* !gfp_mask callers are verified to !skb_zcopy(nskb) */
1936 			if (!gfp_mask) {
1937 				WARN_ON_ONCE(1);
1938 				return -ENOMEM;
1939 			}
1940 			if (skb_uarg(nskb) == skb_uarg(orig))
1941 				return 0;
1942 			if (skb_copy_ubufs(nskb, GFP_ATOMIC))
1943 				return -EIO;
1944 		}
1945 		skb_zcopy_set(nskb, skb_uarg(orig), NULL);
1946 	}
1947 	return 0;
1948 }
1949 
1950 /**
1951  *	skb_copy_ubufs	-	copy userspace skb frags buffers to kernel
1952  *	@skb: the skb to modify
1953  *	@gfp_mask: allocation priority
1954  *
1955  *	This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
1956  *	It will copy all frags into kernel and drop the reference
1957  *	to userspace pages.
1958  *
1959  *	If this function is called from an interrupt gfp_mask() must be
1960  *	%GFP_ATOMIC.
1961  *
1962  *	Returns 0 on success or a negative error code on failure
1963  *	to allocate kernel memory to copy to.
1964  */
skb_copy_ubufs(struct sk_buff * skb,gfp_t gfp_mask)1965 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
1966 {
1967 	int num_frags = skb_shinfo(skb)->nr_frags;
1968 	struct page *page, *head = NULL;
1969 	int i, order, psize, new_frags;
1970 	u32 d_off;
1971 
1972 	if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
1973 		return -EINVAL;
1974 
1975 	if (!skb_frags_readable(skb))
1976 		return -EFAULT;
1977 
1978 	if (!num_frags)
1979 		goto release;
1980 
1981 	/* We might have to allocate high order pages, so compute what minimum
1982 	 * page order is needed.
1983 	 */
1984 	order = 0;
1985 	while ((PAGE_SIZE << order) * MAX_SKB_FRAGS < __skb_pagelen(skb))
1986 		order++;
1987 	psize = (PAGE_SIZE << order);
1988 
1989 	new_frags = (__skb_pagelen(skb) + psize - 1) >> (PAGE_SHIFT + order);
1990 	for (i = 0; i < new_frags; i++) {
1991 		page = alloc_pages(gfp_mask | __GFP_COMP, order);
1992 		if (!page) {
1993 			while (head) {
1994 				struct page *next = (struct page *)page_private(head);
1995 				put_page(head);
1996 				head = next;
1997 			}
1998 			return -ENOMEM;
1999 		}
2000 		set_page_private(page, (unsigned long)head);
2001 		head = page;
2002 	}
2003 
2004 	page = head;
2005 	d_off = 0;
2006 	for (i = 0; i < num_frags; i++) {
2007 		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
2008 		u32 p_off, p_len, copied;
2009 		struct page *p;
2010 		u8 *vaddr;
2011 
2012 		skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
2013 				      p, p_off, p_len, copied) {
2014 			u32 copy, done = 0;
2015 			vaddr = kmap_atomic(p);
2016 
2017 			while (done < p_len) {
2018 				if (d_off == psize) {
2019 					d_off = 0;
2020 					page = (struct page *)page_private(page);
2021 				}
2022 				copy = min_t(u32, psize - d_off, p_len - done);
2023 				memcpy(page_address(page) + d_off,
2024 				       vaddr + p_off + done, copy);
2025 				done += copy;
2026 				d_off += copy;
2027 			}
2028 			kunmap_atomic(vaddr);
2029 		}
2030 	}
2031 
2032 	/* skb frags release userspace buffers */
2033 	for (i = 0; i < num_frags; i++)
2034 		skb_frag_unref(skb, i);
2035 
2036 	/* skb frags point to kernel buffers */
2037 	for (i = 0; i < new_frags - 1; i++) {
2038 		__skb_fill_netmem_desc(skb, i, page_to_netmem(head), 0, psize);
2039 		head = (struct page *)page_private(head);
2040 	}
2041 	__skb_fill_netmem_desc(skb, new_frags - 1, page_to_netmem(head), 0,
2042 			       d_off);
2043 	skb_shinfo(skb)->nr_frags = new_frags;
2044 
2045 release:
2046 	skb_zcopy_clear(skb, false);
2047 	return 0;
2048 }
2049 EXPORT_SYMBOL_GPL(skb_copy_ubufs);
2050 
2051 /**
2052  *	skb_clone	-	duplicate an sk_buff
2053  *	@skb: buffer to clone
2054  *	@gfp_mask: allocation priority
2055  *
2056  *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
2057  *	copies share the same packet data but not structure. The new
2058  *	buffer has a reference count of 1. If the allocation fails the
2059  *	function returns %NULL otherwise the new buffer is returned.
2060  *
2061  *	If this function is called from an interrupt gfp_mask() must be
2062  *	%GFP_ATOMIC.
2063  */
2064 
skb_clone(struct sk_buff * skb,gfp_t gfp_mask)2065 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
2066 {
2067 	struct sk_buff_fclones *fclones = container_of(skb,
2068 						       struct sk_buff_fclones,
2069 						       skb1);
2070 	struct sk_buff *n;
2071 
2072 	if (skb_orphan_frags(skb, gfp_mask))
2073 		return NULL;
2074 
2075 	if (skb->fclone == SKB_FCLONE_ORIG &&
2076 	    refcount_read(&fclones->fclone_ref) == 1) {
2077 		n = &fclones->skb2;
2078 		refcount_set(&fclones->fclone_ref, 2);
2079 		n->fclone = SKB_FCLONE_CLONE;
2080 	} else {
2081 		if (skb_pfmemalloc(skb))
2082 			gfp_mask |= __GFP_MEMALLOC;
2083 
2084 		n = kmem_cache_alloc(net_hotdata.skbuff_cache, gfp_mask);
2085 		if (!n)
2086 			return NULL;
2087 
2088 		n->fclone = SKB_FCLONE_UNAVAILABLE;
2089 	}
2090 
2091 	return __skb_clone(n, skb);
2092 }
2093 EXPORT_SYMBOL(skb_clone);
2094 
skb_headers_offset_update(struct sk_buff * skb,int off)2095 void skb_headers_offset_update(struct sk_buff *skb, int off)
2096 {
2097 	/* Only adjust this if it actually is csum_start rather than csum */
2098 	if (skb->ip_summed == CHECKSUM_PARTIAL)
2099 		skb->csum_start += off;
2100 	/* {transport,network,mac}_header and tail are relative to skb->head */
2101 	skb->transport_header += off;
2102 	skb->network_header   += off;
2103 	if (skb_mac_header_was_set(skb))
2104 		skb->mac_header += off;
2105 	skb->inner_transport_header += off;
2106 	skb->inner_network_header += off;
2107 	skb->inner_mac_header += off;
2108 }
2109 EXPORT_SYMBOL(skb_headers_offset_update);
2110 
skb_copy_header(struct sk_buff * new,const struct sk_buff * old)2111 void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
2112 {
2113 	__copy_skb_header(new, old);
2114 
2115 	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
2116 	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
2117 	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
2118 }
2119 EXPORT_SYMBOL(skb_copy_header);
2120 
skb_alloc_rx_flag(const struct sk_buff * skb)2121 static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
2122 {
2123 	if (skb_pfmemalloc(skb))
2124 		return SKB_ALLOC_RX;
2125 	return 0;
2126 }
2127 
2128 /**
2129  *	skb_copy	-	create private copy of an sk_buff
2130  *	@skb: buffer to copy
2131  *	@gfp_mask: allocation priority
2132  *
2133  *	Make a copy of both an &sk_buff and its data. This is used when the
2134  *	caller wishes to modify the data and needs a private copy of the
2135  *	data to alter. Returns %NULL on failure or the pointer to the buffer
2136  *	on success. The returned buffer has a reference count of 1.
2137  *
2138  *	As by-product this function converts non-linear &sk_buff to linear
2139  *	one, so that &sk_buff becomes completely private and caller is allowed
2140  *	to modify all the data of returned buffer. This means that this
2141  *	function is not recommended for use in circumstances when only
2142  *	header is going to be modified. Use pskb_copy() instead.
2143  */
2144 
skb_copy(const struct sk_buff * skb,gfp_t gfp_mask)2145 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
2146 {
2147 	struct sk_buff *n;
2148 	unsigned int size;
2149 	int headerlen;
2150 
2151 	if (!skb_frags_readable(skb))
2152 		return NULL;
2153 
2154 	if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST))
2155 		return NULL;
2156 
2157 	headerlen = skb_headroom(skb);
2158 	size = skb_end_offset(skb) + skb->data_len;
2159 	n = __alloc_skb(size, gfp_mask,
2160 			skb_alloc_rx_flag(skb), NUMA_NO_NODE);
2161 	if (!n)
2162 		return NULL;
2163 
2164 	/* Set the data pointer */
2165 	skb_reserve(n, headerlen);
2166 	/* Set the tail pointer and length */
2167 	skb_put(n, skb->len);
2168 
2169 	BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
2170 
2171 	skb_copy_header(n, skb);
2172 	return n;
2173 }
2174 EXPORT_SYMBOL(skb_copy);
2175 
2176 /**
2177  *	__pskb_copy_fclone	-  create copy of an sk_buff with private head.
2178  *	@skb: buffer to copy
2179  *	@headroom: headroom of new skb
2180  *	@gfp_mask: allocation priority
2181  *	@fclone: if true allocate the copy of the skb from the fclone
2182  *	cache instead of the head cache; it is recommended to set this
2183  *	to true for the cases where the copy will likely be cloned
2184  *
2185  *	Make a copy of both an &sk_buff and part of its data, located
2186  *	in header. Fragmented data remain shared. This is used when
2187  *	the caller wishes to modify only header of &sk_buff and needs
2188  *	private copy of the header to alter. Returns %NULL on failure
2189  *	or the pointer to the buffer on success.
2190  *	The returned buffer has a reference count of 1.
2191  */
2192 
__pskb_copy_fclone(struct sk_buff * skb,int headroom,gfp_t gfp_mask,bool fclone)2193 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
2194 				   gfp_t gfp_mask, bool fclone)
2195 {
2196 	unsigned int size = skb_headlen(skb) + headroom;
2197 	int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
2198 	struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
2199 
2200 	if (!n)
2201 		goto out;
2202 
2203 	/* Set the data pointer */
2204 	skb_reserve(n, headroom);
2205 	/* Set the tail pointer and length */
2206 	skb_put(n, skb_headlen(skb));
2207 	/* Copy the bytes */
2208 	skb_copy_from_linear_data(skb, n->data, n->len);
2209 
2210 	n->truesize += skb->data_len;
2211 	n->data_len  = skb->data_len;
2212 	n->len	     = skb->len;
2213 
2214 	if (skb_shinfo(skb)->nr_frags) {
2215 		int i;
2216 
2217 		if (skb_orphan_frags(skb, gfp_mask) ||
2218 		    skb_zerocopy_clone(n, skb, gfp_mask)) {
2219 			kfree_skb(n);
2220 			n = NULL;
2221 			goto out;
2222 		}
2223 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2224 			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
2225 			skb_frag_ref(skb, i);
2226 		}
2227 		skb_shinfo(n)->nr_frags = i;
2228 	}
2229 
2230 	if (skb_has_frag_list(skb)) {
2231 		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
2232 		skb_clone_fraglist(n);
2233 	}
2234 
2235 	skb_copy_header(n, skb);
2236 out:
2237 	return n;
2238 }
2239 EXPORT_SYMBOL(__pskb_copy_fclone);
2240 
2241 /**
2242  *	pskb_expand_head - reallocate header of &sk_buff
2243  *	@skb: buffer to reallocate
2244  *	@nhead: room to add at head
2245  *	@ntail: room to add at tail
2246  *	@gfp_mask: allocation priority
2247  *
2248  *	Expands (or creates identical copy, if @nhead and @ntail are zero)
2249  *	header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
2250  *	reference count of 1. Returns zero in the case of success or error,
2251  *	if expansion failed. In the last case, &sk_buff is not changed.
2252  *
2253  *	All the pointers pointing into skb header may change and must be
2254  *	reloaded after call to this function.
2255  */
2256 
pskb_expand_head(struct sk_buff * skb,int nhead,int ntail,gfp_t gfp_mask)2257 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
2258 		     gfp_t gfp_mask)
2259 {
2260 	unsigned int osize = skb_end_offset(skb);
2261 	unsigned int size = osize + nhead + ntail;
2262 	long off;
2263 	u8 *data;
2264 	int i;
2265 
2266 	BUG_ON(nhead < 0);
2267 
2268 	BUG_ON(skb_shared(skb));
2269 
2270 	skb_zcopy_downgrade_managed(skb);
2271 
2272 	if (skb_pfmemalloc(skb))
2273 		gfp_mask |= __GFP_MEMALLOC;
2274 
2275 	data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
2276 	if (!data)
2277 		goto nodata;
2278 	size = SKB_WITH_OVERHEAD(size);
2279 
2280 	/* Copy only real data... and, alas, header. This should be
2281 	 * optimized for the cases when header is void.
2282 	 */
2283 	memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
2284 
2285 	memcpy((struct skb_shared_info *)(data + size),
2286 	       skb_shinfo(skb),
2287 	       offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
2288 
2289 	/*
2290 	 * if shinfo is shared we must drop the old head gracefully, but if it
2291 	 * is not we can just drop the old head and let the existing refcount
2292 	 * be since all we did is relocate the values
2293 	 */
2294 	if (skb_cloned(skb)) {
2295 		if (skb_orphan_frags(skb, gfp_mask))
2296 			goto nofrags;
2297 		if (skb_zcopy(skb))
2298 			refcount_inc(&skb_uarg(skb)->refcnt);
2299 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2300 			skb_frag_ref(skb, i);
2301 
2302 		if (skb_has_frag_list(skb))
2303 			skb_clone_fraglist(skb);
2304 
2305 		skb_release_data(skb, SKB_CONSUMED);
2306 	} else {
2307 		skb_free_head(skb);
2308 	}
2309 	off = (data + nhead) - skb->head;
2310 
2311 	skb->head     = data;
2312 	skb->head_frag = 0;
2313 	skb->data    += off;
2314 
2315 	skb_set_end_offset(skb, size);
2316 #ifdef NET_SKBUFF_DATA_USES_OFFSET
2317 	off           = nhead;
2318 #endif
2319 	skb->tail	      += off;
2320 	skb_headers_offset_update(skb, nhead);
2321 	skb->cloned   = 0;
2322 	skb->hdr_len  = 0;
2323 	skb->nohdr    = 0;
2324 	atomic_set(&skb_shinfo(skb)->dataref, 1);
2325 
2326 	skb_metadata_clear(skb);
2327 
2328 	/* It is not generally safe to change skb->truesize.
2329 	 * For the moment, we really care of rx path, or
2330 	 * when skb is orphaned (not attached to a socket).
2331 	 */
2332 	if (!skb->sk || skb->destructor == sock_edemux)
2333 		skb->truesize += size - osize;
2334 
2335 	return 0;
2336 
2337 nofrags:
2338 	skb_kfree_head(data, size);
2339 nodata:
2340 	return -ENOMEM;
2341 }
2342 EXPORT_SYMBOL(pskb_expand_head);
2343 
2344 /* Make private copy of skb with writable head and some headroom */
2345 
skb_realloc_headroom(struct sk_buff * skb,unsigned int headroom)2346 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
2347 {
2348 	struct sk_buff *skb2;
2349 	int delta = headroom - skb_headroom(skb);
2350 
2351 	if (delta <= 0)
2352 		skb2 = pskb_copy(skb, GFP_ATOMIC);
2353 	else {
2354 		skb2 = skb_clone(skb, GFP_ATOMIC);
2355 		if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
2356 					     GFP_ATOMIC)) {
2357 			kfree_skb(skb2);
2358 			skb2 = NULL;
2359 		}
2360 	}
2361 	return skb2;
2362 }
2363 EXPORT_SYMBOL(skb_realloc_headroom);
2364 
2365 /* Note: We plan to rework this in linux-6.4 */
__skb_unclone_keeptruesize(struct sk_buff * skb,gfp_t pri)2366 int __skb_unclone_keeptruesize(struct sk_buff *skb, gfp_t pri)
2367 {
2368 	unsigned int saved_end_offset, saved_truesize;
2369 	struct skb_shared_info *shinfo;
2370 	int res;
2371 
2372 	saved_end_offset = skb_end_offset(skb);
2373 	saved_truesize = skb->truesize;
2374 
2375 	res = pskb_expand_head(skb, 0, 0, pri);
2376 	if (res)
2377 		return res;
2378 
2379 	skb->truesize = saved_truesize;
2380 
2381 	if (likely(skb_end_offset(skb) == saved_end_offset))
2382 		return 0;
2383 
2384 	/* We can not change skb->end if the original or new value
2385 	 * is SKB_SMALL_HEAD_HEADROOM, as it might break skb_kfree_head().
2386 	 */
2387 	if (saved_end_offset == SKB_SMALL_HEAD_HEADROOM ||
2388 	    skb_end_offset(skb) == SKB_SMALL_HEAD_HEADROOM) {
2389 		/* We think this path should not be taken.
2390 		 * Add a temporary trace to warn us just in case.
2391 		 */
2392 		pr_err_once("__skb_unclone_keeptruesize() skb_end_offset() %u -> %u\n",
2393 			    saved_end_offset, skb_end_offset(skb));
2394 		WARN_ON_ONCE(1);
2395 		return 0;
2396 	}
2397 
2398 	shinfo = skb_shinfo(skb);
2399 
2400 	/* We are about to change back skb->end,
2401 	 * we need to move skb_shinfo() to its new location.
2402 	 */
2403 	memmove(skb->head + saved_end_offset,
2404 		shinfo,
2405 		offsetof(struct skb_shared_info, frags[shinfo->nr_frags]));
2406 
2407 	skb_set_end_offset(skb, saved_end_offset);
2408 
2409 	return 0;
2410 }
2411 
2412 /**
2413  *	skb_expand_head - reallocate header of &sk_buff
2414  *	@skb: buffer to reallocate
2415  *	@headroom: needed headroom
2416  *
2417  *	Unlike skb_realloc_headroom, this one does not allocate a new skb
2418  *	if possible; copies skb->sk to new skb as needed
2419  *	and frees original skb in case of failures.
2420  *
2421  *	It expect increased headroom and generates warning otherwise.
2422  */
2423 
skb_expand_head(struct sk_buff * skb,unsigned int headroom)2424 struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom)
2425 {
2426 	int delta = headroom - skb_headroom(skb);
2427 	int osize = skb_end_offset(skb);
2428 	struct sock *sk = skb->sk;
2429 
2430 	if (WARN_ONCE(delta <= 0,
2431 		      "%s is expecting an increase in the headroom", __func__))
2432 		return skb;
2433 
2434 	delta = SKB_DATA_ALIGN(delta);
2435 	/* pskb_expand_head() might crash, if skb is shared. */
2436 	if (skb_shared(skb) || !is_skb_wmem(skb)) {
2437 		struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
2438 
2439 		if (unlikely(!nskb))
2440 			goto fail;
2441 
2442 		if (sk)
2443 			skb_set_owner_w(nskb, sk);
2444 		consume_skb(skb);
2445 		skb = nskb;
2446 	}
2447 	if (pskb_expand_head(skb, delta, 0, GFP_ATOMIC))
2448 		goto fail;
2449 
2450 	if (sk && is_skb_wmem(skb)) {
2451 		delta = skb_end_offset(skb) - osize;
2452 		refcount_add(delta, &sk->sk_wmem_alloc);
2453 		skb->truesize += delta;
2454 	}
2455 	return skb;
2456 
2457 fail:
2458 	kfree_skb(skb);
2459 	return NULL;
2460 }
2461 EXPORT_SYMBOL(skb_expand_head);
2462 
2463 /**
2464  *	skb_copy_expand	-	copy and expand sk_buff
2465  *	@skb: buffer to copy
2466  *	@newheadroom: new free bytes at head
2467  *	@newtailroom: new free bytes at tail
2468  *	@gfp_mask: allocation priority
2469  *
2470  *	Make a copy of both an &sk_buff and its data and while doing so
2471  *	allocate additional space.
2472  *
2473  *	This is used when the caller wishes to modify the data and needs a
2474  *	private copy of the data to alter as well as more space for new fields.
2475  *	Returns %NULL on failure or the pointer to the buffer
2476  *	on success. The returned buffer has a reference count of 1.
2477  *
2478  *	You must pass %GFP_ATOMIC as the allocation priority if this function
2479  *	is called from an interrupt.
2480  */
skb_copy_expand(const struct sk_buff * skb,int newheadroom,int newtailroom,gfp_t gfp_mask)2481 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
2482 				int newheadroom, int newtailroom,
2483 				gfp_t gfp_mask)
2484 {
2485 	/*
2486 	 *	Allocate the copy buffer
2487 	 */
2488 	int head_copy_len, head_copy_off;
2489 	struct sk_buff *n;
2490 	int oldheadroom;
2491 
2492 	if (!skb_frags_readable(skb))
2493 		return NULL;
2494 
2495 	if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST))
2496 		return NULL;
2497 
2498 	oldheadroom = skb_headroom(skb);
2499 	n = __alloc_skb(newheadroom + skb->len + newtailroom,
2500 			gfp_mask, skb_alloc_rx_flag(skb),
2501 			NUMA_NO_NODE);
2502 	if (!n)
2503 		return NULL;
2504 
2505 	skb_reserve(n, newheadroom);
2506 
2507 	/* Set the tail pointer and length */
2508 	skb_put(n, skb->len);
2509 
2510 	head_copy_len = oldheadroom;
2511 	head_copy_off = 0;
2512 	if (newheadroom <= head_copy_len)
2513 		head_copy_len = newheadroom;
2514 	else
2515 		head_copy_off = newheadroom - head_copy_len;
2516 
2517 	/* Copy the linear header and data. */
2518 	BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
2519 			     skb->len + head_copy_len));
2520 
2521 	skb_copy_header(n, skb);
2522 
2523 	skb_headers_offset_update(n, newheadroom - oldheadroom);
2524 
2525 	return n;
2526 }
2527 EXPORT_SYMBOL(skb_copy_expand);
2528 
2529 /**
2530  *	__skb_pad		-	zero pad the tail of an skb
2531  *	@skb: buffer to pad
2532  *	@pad: space to pad
2533  *	@free_on_error: free buffer on error
2534  *
2535  *	Ensure that a buffer is followed by a padding area that is zero
2536  *	filled. Used by network drivers which may DMA or transfer data
2537  *	beyond the buffer end onto the wire.
2538  *
2539  *	May return error in out of memory cases. The skb is freed on error
2540  *	if @free_on_error is true.
2541  */
2542 
__skb_pad(struct sk_buff * skb,int pad,bool free_on_error)2543 int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
2544 {
2545 	int err;
2546 	int ntail;
2547 
2548 	/* If the skbuff is non linear tailroom is always zero.. */
2549 	if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
2550 		memset(skb->data+skb->len, 0, pad);
2551 		return 0;
2552 	}
2553 
2554 	ntail = skb->data_len + pad - (skb->end - skb->tail);
2555 	if (likely(skb_cloned(skb) || ntail > 0)) {
2556 		err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
2557 		if (unlikely(err))
2558 			goto free_skb;
2559 	}
2560 
2561 	/* FIXME: The use of this function with non-linear skb's really needs
2562 	 * to be audited.
2563 	 */
2564 	err = skb_linearize(skb);
2565 	if (unlikely(err))
2566 		goto free_skb;
2567 
2568 	memset(skb->data + skb->len, 0, pad);
2569 	return 0;
2570 
2571 free_skb:
2572 	if (free_on_error)
2573 		kfree_skb(skb);
2574 	return err;
2575 }
2576 EXPORT_SYMBOL(__skb_pad);
2577 
2578 /**
2579  *	pskb_put - add data to the tail of a potentially fragmented buffer
2580  *	@skb: start of the buffer to use
2581  *	@tail: tail fragment of the buffer to use
2582  *	@len: amount of data to add
2583  *
2584  *	This function extends the used data area of the potentially
2585  *	fragmented buffer. @tail must be the last fragment of @skb -- or
2586  *	@skb itself. If this would exceed the total buffer size the kernel
2587  *	will panic. A pointer to the first byte of the extra data is
2588  *	returned.
2589  */
2590 
pskb_put(struct sk_buff * skb,struct sk_buff * tail,int len)2591 void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
2592 {
2593 	if (tail != skb) {
2594 		skb->data_len += len;
2595 		skb->len += len;
2596 	}
2597 	return skb_put(tail, len);
2598 }
2599 EXPORT_SYMBOL_GPL(pskb_put);
2600 
2601 /**
2602  *	skb_put - add data to a buffer
2603  *	@skb: buffer to use
2604  *	@len: amount of data to add
2605  *
2606  *	This function extends the used data area of the buffer. If this would
2607  *	exceed the total buffer size the kernel will panic. A pointer to the
2608  *	first byte of the extra data is returned.
2609  */
skb_put(struct sk_buff * skb,unsigned int len)2610 void *skb_put(struct sk_buff *skb, unsigned int len)
2611 {
2612 	void *tmp = skb_tail_pointer(skb);
2613 	SKB_LINEAR_ASSERT(skb);
2614 	skb->tail += len;
2615 	skb->len  += len;
2616 	if (unlikely(skb->tail > skb->end))
2617 		skb_over_panic(skb, len, __builtin_return_address(0));
2618 	return tmp;
2619 }
2620 EXPORT_SYMBOL(skb_put);
2621 
2622 /**
2623  *	skb_push - add data to the start of a buffer
2624  *	@skb: buffer to use
2625  *	@len: amount of data to add
2626  *
2627  *	This function extends the used data area of the buffer at the buffer
2628  *	start. If this would exceed the total buffer headroom the kernel will
2629  *	panic. A pointer to the first byte of the extra data is returned.
2630  */
skb_push(struct sk_buff * skb,unsigned int len)2631 void *skb_push(struct sk_buff *skb, unsigned int len)
2632 {
2633 	skb->data -= len;
2634 	skb->len  += len;
2635 	if (unlikely(skb->data < skb->head))
2636 		skb_under_panic(skb, len, __builtin_return_address(0));
2637 	return skb->data;
2638 }
2639 EXPORT_SYMBOL(skb_push);
2640 
2641 /**
2642  *	skb_pull - remove data from the start of a buffer
2643  *	@skb: buffer to use
2644  *	@len: amount of data to remove
2645  *
2646  *	This function removes data from the start of a buffer, returning
2647  *	the memory to the headroom. A pointer to the next data in the buffer
2648  *	is returned. Once the data has been pulled future pushes will overwrite
2649  *	the old data.
2650  */
skb_pull(struct sk_buff * skb,unsigned int len)2651 void *skb_pull(struct sk_buff *skb, unsigned int len)
2652 {
2653 	return skb_pull_inline(skb, len);
2654 }
2655 EXPORT_SYMBOL(skb_pull);
2656 
2657 /**
2658  *	skb_pull_data - remove data from the start of a buffer returning its
2659  *	original position.
2660  *	@skb: buffer to use
2661  *	@len: amount of data to remove
2662  *
2663  *	This function removes data from the start of a buffer, returning
2664  *	the memory to the headroom. A pointer to the original data in the buffer
2665  *	is returned after checking if there is enough data to pull. Once the
2666  *	data has been pulled future pushes will overwrite the old data.
2667  */
skb_pull_data(struct sk_buff * skb,size_t len)2668 void *skb_pull_data(struct sk_buff *skb, size_t len)
2669 {
2670 	void *data = skb->data;
2671 
2672 	if (skb->len < len)
2673 		return NULL;
2674 
2675 	skb_pull(skb, len);
2676 
2677 	return data;
2678 }
2679 EXPORT_SYMBOL(skb_pull_data);
2680 
2681 /**
2682  *	skb_trim - remove end from a buffer
2683  *	@skb: buffer to alter
2684  *	@len: new length
2685  *
2686  *	Cut the length of a buffer down by removing data from the tail. If
2687  *	the buffer is already under the length specified it is not modified.
2688  *	The skb must be linear.
2689  */
skb_trim(struct sk_buff * skb,unsigned int len)2690 void skb_trim(struct sk_buff *skb, unsigned int len)
2691 {
2692 	if (skb->len > len)
2693 		__skb_trim(skb, len);
2694 }
2695 EXPORT_SYMBOL(skb_trim);
2696 
2697 /* Trims skb to length len. It can change skb pointers.
2698  */
2699 
___pskb_trim(struct sk_buff * skb,unsigned int len)2700 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
2701 {
2702 	struct sk_buff **fragp;
2703 	struct sk_buff *frag;
2704 	int offset = skb_headlen(skb);
2705 	int nfrags = skb_shinfo(skb)->nr_frags;
2706 	int i;
2707 	int err;
2708 
2709 	if (skb_cloned(skb) &&
2710 	    unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
2711 		return err;
2712 
2713 	i = 0;
2714 	if (offset >= len)
2715 		goto drop_pages;
2716 
2717 	for (; i < nfrags; i++) {
2718 		int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2719 
2720 		if (end < len) {
2721 			offset = end;
2722 			continue;
2723 		}
2724 
2725 		skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
2726 
2727 drop_pages:
2728 		skb_shinfo(skb)->nr_frags = i;
2729 
2730 		for (; i < nfrags; i++)
2731 			skb_frag_unref(skb, i);
2732 
2733 		if (skb_has_frag_list(skb))
2734 			skb_drop_fraglist(skb);
2735 		goto done;
2736 	}
2737 
2738 	for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
2739 	     fragp = &frag->next) {
2740 		int end = offset + frag->len;
2741 
2742 		if (skb_shared(frag)) {
2743 			struct sk_buff *nfrag;
2744 
2745 			nfrag = skb_clone(frag, GFP_ATOMIC);
2746 			if (unlikely(!nfrag))
2747 				return -ENOMEM;
2748 
2749 			nfrag->next = frag->next;
2750 			consume_skb(frag);
2751 			frag = nfrag;
2752 			*fragp = frag;
2753 		}
2754 
2755 		if (end < len) {
2756 			offset = end;
2757 			continue;
2758 		}
2759 
2760 		if (end > len &&
2761 		    unlikely((err = pskb_trim(frag, len - offset))))
2762 			return err;
2763 
2764 		if (frag->next)
2765 			skb_drop_list(&frag->next);
2766 		break;
2767 	}
2768 
2769 done:
2770 	if (len > skb_headlen(skb)) {
2771 		skb->data_len -= skb->len - len;
2772 		skb->len       = len;
2773 	} else {
2774 		skb->len       = len;
2775 		skb->data_len  = 0;
2776 		skb_set_tail_pointer(skb, len);
2777 	}
2778 
2779 	if (!skb->sk || skb->destructor == sock_edemux)
2780 		skb_condense(skb);
2781 	return 0;
2782 }
2783 EXPORT_SYMBOL(___pskb_trim);
2784 
2785 /* Note : use pskb_trim_rcsum() instead of calling this directly
2786  */
pskb_trim_rcsum_slow(struct sk_buff * skb,unsigned int len)2787 int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
2788 {
2789 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
2790 		int delta = skb->len - len;
2791 
2792 		skb->csum = csum_block_sub(skb->csum,
2793 					   skb_checksum(skb, len, delta, 0),
2794 					   len);
2795 	} else if (skb->ip_summed == CHECKSUM_PARTIAL) {
2796 		int hdlen = (len > skb_headlen(skb)) ? skb_headlen(skb) : len;
2797 		int offset = skb_checksum_start_offset(skb) + skb->csum_offset;
2798 
2799 		if (offset + sizeof(__sum16) > hdlen)
2800 			return -EINVAL;
2801 	}
2802 	return __pskb_trim(skb, len);
2803 }
2804 EXPORT_SYMBOL(pskb_trim_rcsum_slow);
2805 
2806 /**
2807  *	__pskb_pull_tail - advance tail of skb header
2808  *	@skb: buffer to reallocate
2809  *	@delta: number of bytes to advance tail
2810  *
2811  *	The function makes a sense only on a fragmented &sk_buff,
2812  *	it expands header moving its tail forward and copying necessary
2813  *	data from fragmented part.
2814  *
2815  *	&sk_buff MUST have reference count of 1.
2816  *
2817  *	Returns %NULL (and &sk_buff does not change) if pull failed
2818  *	or value of new tail of skb in the case of success.
2819  *
2820  *	All the pointers pointing into skb header may change and must be
2821  *	reloaded after call to this function.
2822  */
2823 
2824 /* Moves tail of skb head forward, copying data from fragmented part,
2825  * when it is necessary.
2826  * 1. It may fail due to malloc failure.
2827  * 2. It may change skb pointers.
2828  *
2829  * It is pretty complicated. Luckily, it is called only in exceptional cases.
2830  */
__pskb_pull_tail(struct sk_buff * skb,int delta)2831 void *__pskb_pull_tail(struct sk_buff *skb, int delta)
2832 {
2833 	/* If skb has not enough free space at tail, get new one
2834 	 * plus 128 bytes for future expansions. If we have enough
2835 	 * room at tail, reallocate without expansion only if skb is cloned.
2836 	 */
2837 	int i, k, eat = (skb->tail + delta) - skb->end;
2838 
2839 	if (!skb_frags_readable(skb))
2840 		return NULL;
2841 
2842 	if (eat > 0 || skb_cloned(skb)) {
2843 		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
2844 				     GFP_ATOMIC))
2845 			return NULL;
2846 	}
2847 
2848 	BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
2849 			     skb_tail_pointer(skb), delta));
2850 
2851 	/* Optimization: no fragments, no reasons to preestimate
2852 	 * size of pulled pages. Superb.
2853 	 */
2854 	if (!skb_has_frag_list(skb))
2855 		goto pull_pages;
2856 
2857 	/* Estimate size of pulled pages. */
2858 	eat = delta;
2859 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2860 		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2861 
2862 		if (size >= eat)
2863 			goto pull_pages;
2864 		eat -= size;
2865 	}
2866 
2867 	/* If we need update frag list, we are in troubles.
2868 	 * Certainly, it is possible to add an offset to skb data,
2869 	 * but taking into account that pulling is expected to
2870 	 * be very rare operation, it is worth to fight against
2871 	 * further bloating skb head and crucify ourselves here instead.
2872 	 * Pure masohism, indeed. 8)8)
2873 	 */
2874 	if (eat) {
2875 		struct sk_buff *list = skb_shinfo(skb)->frag_list;
2876 		struct sk_buff *clone = NULL;
2877 		struct sk_buff *insp = NULL;
2878 
2879 		do {
2880 			if (list->len <= eat) {
2881 				/* Eaten as whole. */
2882 				eat -= list->len;
2883 				list = list->next;
2884 				insp = list;
2885 			} else {
2886 				/* Eaten partially. */
2887 				if (skb_is_gso(skb) && !list->head_frag &&
2888 				    skb_headlen(list))
2889 					skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
2890 
2891 				if (skb_shared(list)) {
2892 					/* Sucks! We need to fork list. :-( */
2893 					clone = skb_clone(list, GFP_ATOMIC);
2894 					if (!clone)
2895 						return NULL;
2896 					insp = list->next;
2897 					list = clone;
2898 				} else {
2899 					/* This may be pulled without
2900 					 * problems. */
2901 					insp = list;
2902 				}
2903 				if (!pskb_pull(list, eat)) {
2904 					kfree_skb(clone);
2905 					return NULL;
2906 				}
2907 				break;
2908 			}
2909 		} while (eat);
2910 
2911 		/* Free pulled out fragments. */
2912 		while ((list = skb_shinfo(skb)->frag_list) != insp) {
2913 			skb_shinfo(skb)->frag_list = list->next;
2914 			consume_skb(list);
2915 		}
2916 		/* And insert new clone at head. */
2917 		if (clone) {
2918 			clone->next = list;
2919 			skb_shinfo(skb)->frag_list = clone;
2920 		}
2921 	}
2922 	/* Success! Now we may commit changes to skb data. */
2923 
2924 pull_pages:
2925 	eat = delta;
2926 	k = 0;
2927 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2928 		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2929 
2930 		if (size <= eat) {
2931 			skb_frag_unref(skb, i);
2932 			eat -= size;
2933 		} else {
2934 			skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
2935 
2936 			*frag = skb_shinfo(skb)->frags[i];
2937 			if (eat) {
2938 				skb_frag_off_add(frag, eat);
2939 				skb_frag_size_sub(frag, eat);
2940 				if (!i)
2941 					goto end;
2942 				eat = 0;
2943 			}
2944 			k++;
2945 		}
2946 	}
2947 	skb_shinfo(skb)->nr_frags = k;
2948 
2949 end:
2950 	skb->tail     += delta;
2951 	skb->data_len -= delta;
2952 
2953 	if (!skb->data_len)
2954 		skb_zcopy_clear(skb, false);
2955 
2956 	return skb_tail_pointer(skb);
2957 }
2958 EXPORT_SYMBOL(__pskb_pull_tail);
2959 
2960 /**
2961  *	skb_copy_bits - copy bits from skb to kernel buffer
2962  *	@skb: source skb
2963  *	@offset: offset in source
2964  *	@to: destination buffer
2965  *	@len: number of bytes to copy
2966  *
2967  *	Copy the specified number of bytes from the source skb to the
2968  *	destination buffer.
2969  *
2970  *	CAUTION ! :
2971  *		If its prototype is ever changed,
2972  *		check arch/{*}/net/{*}.S files,
2973  *		since it is called from BPF assembly code.
2974  */
skb_copy_bits(const struct sk_buff * skb,int offset,void * to,int len)2975 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
2976 {
2977 	int start = skb_headlen(skb);
2978 	struct sk_buff *frag_iter;
2979 	int i, copy;
2980 
2981 	if (offset > (int)skb->len - len)
2982 		goto fault;
2983 
2984 	/* Copy header. */
2985 	if ((copy = start - offset) > 0) {
2986 		if (copy > len)
2987 			copy = len;
2988 		skb_copy_from_linear_data_offset(skb, offset, to, copy);
2989 		if ((len -= copy) == 0)
2990 			return 0;
2991 		offset += copy;
2992 		to     += copy;
2993 	}
2994 
2995 	if (!skb_frags_readable(skb))
2996 		goto fault;
2997 
2998 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2999 		int end;
3000 		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
3001 
3002 		WARN_ON(start > offset + len);
3003 
3004 		end = start + skb_frag_size(f);
3005 		if ((copy = end - offset) > 0) {
3006 			u32 p_off, p_len, copied;
3007 			struct page *p;
3008 			u8 *vaddr;
3009 
3010 			if (copy > len)
3011 				copy = len;
3012 
3013 			skb_frag_foreach_page(f,
3014 					      skb_frag_off(f) + offset - start,
3015 					      copy, p, p_off, p_len, copied) {
3016 				vaddr = kmap_atomic(p);
3017 				memcpy(to + copied, vaddr + p_off, p_len);
3018 				kunmap_atomic(vaddr);
3019 			}
3020 
3021 			if ((len -= copy) == 0)
3022 				return 0;
3023 			offset += copy;
3024 			to     += copy;
3025 		}
3026 		start = end;
3027 	}
3028 
3029 	skb_walk_frags(skb, frag_iter) {
3030 		int end;
3031 
3032 		WARN_ON(start > offset + len);
3033 
3034 		end = start + frag_iter->len;
3035 		if ((copy = end - offset) > 0) {
3036 			if (copy > len)
3037 				copy = len;
3038 			if (skb_copy_bits(frag_iter, offset - start, to, copy))
3039 				goto fault;
3040 			if ((len -= copy) == 0)
3041 				return 0;
3042 			offset += copy;
3043 			to     += copy;
3044 		}
3045 		start = end;
3046 	}
3047 
3048 	if (!len)
3049 		return 0;
3050 
3051 fault:
3052 	return -EFAULT;
3053 }
3054 EXPORT_SYMBOL(skb_copy_bits);
3055 
3056 /*
3057  * Callback from splice_to_pipe(), if we need to release some pages
3058  * at the end of the spd in case we error'ed out in filling the pipe.
3059  */
sock_spd_release(struct splice_pipe_desc * spd,unsigned int i)3060 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
3061 {
3062 	put_page(spd->pages[i]);
3063 }
3064 
linear_to_page(struct page * page,unsigned int * len,unsigned int * offset,struct sock * sk)3065 static struct page *linear_to_page(struct page *page, unsigned int *len,
3066 				   unsigned int *offset,
3067 				   struct sock *sk)
3068 {
3069 	struct page_frag *pfrag = sk_page_frag(sk);
3070 
3071 	if (!sk_page_frag_refill(sk, pfrag))
3072 		return NULL;
3073 
3074 	*len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
3075 
3076 	memcpy(page_address(pfrag->page) + pfrag->offset,
3077 	       page_address(page) + *offset, *len);
3078 	*offset = pfrag->offset;
3079 	pfrag->offset += *len;
3080 
3081 	return pfrag->page;
3082 }
3083 
spd_can_coalesce(const struct splice_pipe_desc * spd,struct page * page,unsigned int offset)3084 static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
3085 			     struct page *page,
3086 			     unsigned int offset)
3087 {
3088 	return	spd->nr_pages &&
3089 		spd->pages[spd->nr_pages - 1] == page &&
3090 		(spd->partial[spd->nr_pages - 1].offset +
3091 		 spd->partial[spd->nr_pages - 1].len == offset);
3092 }
3093 
3094 /*
3095  * Fill page/offset/length into spd, if it can hold more pages.
3096  */
spd_fill_page(struct splice_pipe_desc * spd,struct pipe_inode_info * pipe,struct page * page,unsigned int * len,unsigned int offset,bool linear,struct sock * sk)3097 static bool spd_fill_page(struct splice_pipe_desc *spd,
3098 			  struct pipe_inode_info *pipe, struct page *page,
3099 			  unsigned int *len, unsigned int offset,
3100 			  bool linear,
3101 			  struct sock *sk)
3102 {
3103 	if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
3104 		return true;
3105 
3106 	if (linear) {
3107 		page = linear_to_page(page, len, &offset, sk);
3108 		if (!page)
3109 			return true;
3110 	}
3111 	if (spd_can_coalesce(spd, page, offset)) {
3112 		spd->partial[spd->nr_pages - 1].len += *len;
3113 		return false;
3114 	}
3115 	get_page(page);
3116 	spd->pages[spd->nr_pages] = page;
3117 	spd->partial[spd->nr_pages].len = *len;
3118 	spd->partial[spd->nr_pages].offset = offset;
3119 	spd->nr_pages++;
3120 
3121 	return false;
3122 }
3123 
__splice_segment(struct page * page,unsigned int poff,unsigned int plen,unsigned int * off,unsigned int * len,struct splice_pipe_desc * spd,bool linear,struct sock * sk,struct pipe_inode_info * pipe)3124 static bool __splice_segment(struct page *page, unsigned int poff,
3125 			     unsigned int plen, unsigned int *off,
3126 			     unsigned int *len,
3127 			     struct splice_pipe_desc *spd, bool linear,
3128 			     struct sock *sk,
3129 			     struct pipe_inode_info *pipe)
3130 {
3131 	if (!*len)
3132 		return true;
3133 
3134 	/* skip this segment if already processed */
3135 	if (*off >= plen) {
3136 		*off -= plen;
3137 		return false;
3138 	}
3139 
3140 	/* ignore any bits we already processed */
3141 	poff += *off;
3142 	plen -= *off;
3143 	*off = 0;
3144 
3145 	do {
3146 		unsigned int flen = min(*len, plen);
3147 
3148 		if (spd_fill_page(spd, pipe, page, &flen, poff,
3149 				  linear, sk))
3150 			return true;
3151 		poff += flen;
3152 		plen -= flen;
3153 		*len -= flen;
3154 	} while (*len && plen);
3155 
3156 	return false;
3157 }
3158 
3159 /*
3160  * Map linear and fragment data from the skb to spd. It reports true if the
3161  * pipe is full or if we already spliced the requested length.
3162  */
__skb_splice_bits(struct sk_buff * skb,struct pipe_inode_info * pipe,unsigned int * offset,unsigned int * len,struct splice_pipe_desc * spd,struct sock * sk)3163 static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
3164 			      unsigned int *offset, unsigned int *len,
3165 			      struct splice_pipe_desc *spd, struct sock *sk)
3166 {
3167 	int seg;
3168 	struct sk_buff *iter;
3169 
3170 	/* map the linear part :
3171 	 * If skb->head_frag is set, this 'linear' part is backed by a
3172 	 * fragment, and if the head is not shared with any clones then
3173 	 * we can avoid a copy since we own the head portion of this page.
3174 	 */
3175 	if (__splice_segment(virt_to_page(skb->data),
3176 			     (unsigned long) skb->data & (PAGE_SIZE - 1),
3177 			     skb_headlen(skb),
3178 			     offset, len, spd,
3179 			     skb_head_is_locked(skb),
3180 			     sk, pipe))
3181 		return true;
3182 
3183 	/*
3184 	 * then map the fragments
3185 	 */
3186 	if (!skb_frags_readable(skb))
3187 		return false;
3188 
3189 	for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
3190 		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
3191 
3192 		if (WARN_ON_ONCE(!skb_frag_page(f)))
3193 			return false;
3194 
3195 		if (__splice_segment(skb_frag_page(f),
3196 				     skb_frag_off(f), skb_frag_size(f),
3197 				     offset, len, spd, false, sk, pipe))
3198 			return true;
3199 	}
3200 
3201 	skb_walk_frags(skb, iter) {
3202 		if (*offset >= iter->len) {
3203 			*offset -= iter->len;
3204 			continue;
3205 		}
3206 		/* __skb_splice_bits() only fails if the output has no room
3207 		 * left, so no point in going over the frag_list for the error
3208 		 * case.
3209 		 */
3210 		if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
3211 			return true;
3212 	}
3213 
3214 	return false;
3215 }
3216 
3217 /*
3218  * Map data from the skb to a pipe. Should handle both the linear part,
3219  * the fragments, and the frag list.
3220  */
skb_splice_bits(struct sk_buff * skb,struct sock * sk,unsigned int offset,struct pipe_inode_info * pipe,unsigned int tlen,unsigned int flags)3221 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3222 		    struct pipe_inode_info *pipe, unsigned int tlen,
3223 		    unsigned int flags)
3224 {
3225 	struct partial_page partial[MAX_SKB_FRAGS];
3226 	struct page *pages[MAX_SKB_FRAGS];
3227 	struct splice_pipe_desc spd = {
3228 		.pages = pages,
3229 		.partial = partial,
3230 		.nr_pages_max = MAX_SKB_FRAGS,
3231 		.ops = &nosteal_pipe_buf_ops,
3232 		.spd_release = sock_spd_release,
3233 	};
3234 	int ret = 0;
3235 
3236 	__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
3237 
3238 	if (spd.nr_pages)
3239 		ret = splice_to_pipe(pipe, &spd);
3240 
3241 	return ret;
3242 }
3243 EXPORT_SYMBOL_GPL(skb_splice_bits);
3244 
sendmsg_locked(struct sock * sk,struct msghdr * msg)3245 static int sendmsg_locked(struct sock *sk, struct msghdr *msg)
3246 {
3247 	struct socket *sock = sk->sk_socket;
3248 	size_t size = msg_data_left(msg);
3249 
3250 	if (!sock)
3251 		return -EINVAL;
3252 
3253 	if (!sock->ops->sendmsg_locked)
3254 		return sock_no_sendmsg_locked(sk, msg, size);
3255 
3256 	return sock->ops->sendmsg_locked(sk, msg, size);
3257 }
3258 
sendmsg_unlocked(struct sock * sk,struct msghdr * msg)3259 static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg)
3260 {
3261 	struct socket *sock = sk->sk_socket;
3262 
3263 	if (!sock)
3264 		return -EINVAL;
3265 	return sock_sendmsg(sock, msg);
3266 }
3267 
3268 typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg);
__skb_send_sock(struct sock * sk,struct sk_buff * skb,int offset,int len,sendmsg_func sendmsg)3269 static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
3270 			   int len, sendmsg_func sendmsg)
3271 {
3272 	unsigned int orig_len = len;
3273 	struct sk_buff *head = skb;
3274 	unsigned short fragidx;
3275 	int slen, ret;
3276 
3277 do_frag_list:
3278 
3279 	/* Deal with head data */
3280 	while (offset < skb_headlen(skb) && len) {
3281 		struct kvec kv;
3282 		struct msghdr msg;
3283 
3284 		slen = min_t(int, len, skb_headlen(skb) - offset);
3285 		kv.iov_base = skb->data + offset;
3286 		kv.iov_len = slen;
3287 		memset(&msg, 0, sizeof(msg));
3288 		msg.msg_flags = MSG_DONTWAIT;
3289 
3290 		iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &kv, 1, slen);
3291 		ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
3292 				      sendmsg_unlocked, sk, &msg);
3293 		if (ret <= 0)
3294 			goto error;
3295 
3296 		offset += ret;
3297 		len -= ret;
3298 	}
3299 
3300 	/* All the data was skb head? */
3301 	if (!len)
3302 		goto out;
3303 
3304 	/* Make offset relative to start of frags */
3305 	offset -= skb_headlen(skb);
3306 
3307 	/* Find where we are in frag list */
3308 	for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
3309 		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
3310 
3311 		if (offset < skb_frag_size(frag))
3312 			break;
3313 
3314 		offset -= skb_frag_size(frag);
3315 	}
3316 
3317 	for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
3318 		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
3319 
3320 		slen = min_t(size_t, len, skb_frag_size(frag) - offset);
3321 
3322 		while (slen) {
3323 			struct bio_vec bvec;
3324 			struct msghdr msg = {
3325 				.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT,
3326 			};
3327 
3328 			bvec_set_page(&bvec, skb_frag_page(frag), slen,
3329 				      skb_frag_off(frag) + offset);
3330 			iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1,
3331 				      slen);
3332 
3333 			ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
3334 					      sendmsg_unlocked, sk, &msg);
3335 			if (ret <= 0)
3336 				goto error;
3337 
3338 			len -= ret;
3339 			offset += ret;
3340 			slen -= ret;
3341 		}
3342 
3343 		offset = 0;
3344 	}
3345 
3346 	if (len) {
3347 		/* Process any frag lists */
3348 
3349 		if (skb == head) {
3350 			if (skb_has_frag_list(skb)) {
3351 				skb = skb_shinfo(skb)->frag_list;
3352 				goto do_frag_list;
3353 			}
3354 		} else if (skb->next) {
3355 			skb = skb->next;
3356 			goto do_frag_list;
3357 		}
3358 	}
3359 
3360 out:
3361 	return orig_len - len;
3362 
3363 error:
3364 	return orig_len == len ? ret : orig_len - len;
3365 }
3366 
3367 /* Send skb data on a socket. Socket must be locked. */
skb_send_sock_locked(struct sock * sk,struct sk_buff * skb,int offset,int len)3368 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
3369 			 int len)
3370 {
3371 	return __skb_send_sock(sk, skb, offset, len, sendmsg_locked);
3372 }
3373 EXPORT_SYMBOL_GPL(skb_send_sock_locked);
3374 
3375 /* Send skb data on a socket. Socket must be unlocked. */
skb_send_sock(struct sock * sk,struct sk_buff * skb,int offset,int len)3376 int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
3377 {
3378 	return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked);
3379 }
3380 
3381 /**
3382  *	skb_store_bits - store bits from kernel buffer to skb
3383  *	@skb: destination buffer
3384  *	@offset: offset in destination
3385  *	@from: source buffer
3386  *	@len: number of bytes to copy
3387  *
3388  *	Copy the specified number of bytes from the source buffer to the
3389  *	destination skb.  This function handles all the messy bits of
3390  *	traversing fragment lists and such.
3391  */
3392 
skb_store_bits(struct sk_buff * skb,int offset,const void * from,int len)3393 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
3394 {
3395 	int start = skb_headlen(skb);
3396 	struct sk_buff *frag_iter;
3397 	int i, copy;
3398 
3399 	if (offset > (int)skb->len - len)
3400 		goto fault;
3401 
3402 	if ((copy = start - offset) > 0) {
3403 		if (copy > len)
3404 			copy = len;
3405 		skb_copy_to_linear_data_offset(skb, offset, from, copy);
3406 		if ((len -= copy) == 0)
3407 			return 0;
3408 		offset += copy;
3409 		from += copy;
3410 	}
3411 
3412 	if (!skb_frags_readable(skb))
3413 		goto fault;
3414 
3415 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3416 		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3417 		int end;
3418 
3419 		WARN_ON(start > offset + len);
3420 
3421 		end = start + skb_frag_size(frag);
3422 		if ((copy = end - offset) > 0) {
3423 			u32 p_off, p_len, copied;
3424 			struct page *p;
3425 			u8 *vaddr;
3426 
3427 			if (copy > len)
3428 				copy = len;
3429 
3430 			skb_frag_foreach_page(frag,
3431 					      skb_frag_off(frag) + offset - start,
3432 					      copy, p, p_off, p_len, copied) {
3433 				vaddr = kmap_atomic(p);
3434 				memcpy(vaddr + p_off, from + copied, p_len);
3435 				kunmap_atomic(vaddr);
3436 			}
3437 
3438 			if ((len -= copy) == 0)
3439 				return 0;
3440 			offset += copy;
3441 			from += copy;
3442 		}
3443 		start = end;
3444 	}
3445 
3446 	skb_walk_frags(skb, frag_iter) {
3447 		int end;
3448 
3449 		WARN_ON(start > offset + len);
3450 
3451 		end = start + frag_iter->len;
3452 		if ((copy = end - offset) > 0) {
3453 			if (copy > len)
3454 				copy = len;
3455 			if (skb_store_bits(frag_iter, offset - start,
3456 					   from, copy))
3457 				goto fault;
3458 			if ((len -= copy) == 0)
3459 				return 0;
3460 			offset += copy;
3461 			from += copy;
3462 		}
3463 		start = end;
3464 	}
3465 	if (!len)
3466 		return 0;
3467 
3468 fault:
3469 	return -EFAULT;
3470 }
3471 EXPORT_SYMBOL(skb_store_bits);
3472 
3473 /* Checksum skb data. */
__skb_checksum(const struct sk_buff * skb,int offset,int len,__wsum csum,const struct skb_checksum_ops * ops)3474 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3475 		      __wsum csum, const struct skb_checksum_ops *ops)
3476 {
3477 	int start = skb_headlen(skb);
3478 	int i, copy = start - offset;
3479 	struct sk_buff *frag_iter;
3480 	int pos = 0;
3481 
3482 	/* Checksum header. */
3483 	if (copy > 0) {
3484 		if (copy > len)
3485 			copy = len;
3486 		csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
3487 				       skb->data + offset, copy, csum);
3488 		if ((len -= copy) == 0)
3489 			return csum;
3490 		offset += copy;
3491 		pos	= copy;
3492 	}
3493 
3494 	if (WARN_ON_ONCE(!skb_frags_readable(skb)))
3495 		return 0;
3496 
3497 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3498 		int end;
3499 		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3500 
3501 		WARN_ON(start > offset + len);
3502 
3503 		end = start + skb_frag_size(frag);
3504 		if ((copy = end - offset) > 0) {
3505 			u32 p_off, p_len, copied;
3506 			struct page *p;
3507 			__wsum csum2;
3508 			u8 *vaddr;
3509 
3510 			if (copy > len)
3511 				copy = len;
3512 
3513 			skb_frag_foreach_page(frag,
3514 					      skb_frag_off(frag) + offset - start,
3515 					      copy, p, p_off, p_len, copied) {
3516 				vaddr = kmap_atomic(p);
3517 				csum2 = INDIRECT_CALL_1(ops->update,
3518 							csum_partial_ext,
3519 							vaddr + p_off, p_len, 0);
3520 				kunmap_atomic(vaddr);
3521 				csum = INDIRECT_CALL_1(ops->combine,
3522 						       csum_block_add_ext, csum,
3523 						       csum2, pos, p_len);
3524 				pos += p_len;
3525 			}
3526 
3527 			if (!(len -= copy))
3528 				return csum;
3529 			offset += copy;
3530 		}
3531 		start = end;
3532 	}
3533 
3534 	skb_walk_frags(skb, frag_iter) {
3535 		int end;
3536 
3537 		WARN_ON(start > offset + len);
3538 
3539 		end = start + frag_iter->len;
3540 		if ((copy = end - offset) > 0) {
3541 			__wsum csum2;
3542 			if (copy > len)
3543 				copy = len;
3544 			csum2 = __skb_checksum(frag_iter, offset - start,
3545 					       copy, 0, ops);
3546 			csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
3547 					       csum, csum2, pos, copy);
3548 			if ((len -= copy) == 0)
3549 				return csum;
3550 			offset += copy;
3551 			pos    += copy;
3552 		}
3553 		start = end;
3554 	}
3555 	BUG_ON(len);
3556 
3557 	return csum;
3558 }
3559 EXPORT_SYMBOL(__skb_checksum);
3560 
skb_checksum(const struct sk_buff * skb,int offset,int len,__wsum csum)3561 __wsum skb_checksum(const struct sk_buff *skb, int offset,
3562 		    int len, __wsum csum)
3563 {
3564 	const struct skb_checksum_ops ops = {
3565 		.update  = csum_partial_ext,
3566 		.combine = csum_block_add_ext,
3567 	};
3568 
3569 	return __skb_checksum(skb, offset, len, csum, &ops);
3570 }
3571 EXPORT_SYMBOL(skb_checksum);
3572 
3573 /* Both of above in one bottle. */
3574 
skb_copy_and_csum_bits(const struct sk_buff * skb,int offset,u8 * to,int len)3575 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
3576 				    u8 *to, int len)
3577 {
3578 	int start = skb_headlen(skb);
3579 	int i, copy = start - offset;
3580 	struct sk_buff *frag_iter;
3581 	int pos = 0;
3582 	__wsum csum = 0;
3583 
3584 	/* Copy header. */
3585 	if (copy > 0) {
3586 		if (copy > len)
3587 			copy = len;
3588 		csum = csum_partial_copy_nocheck(skb->data + offset, to,
3589 						 copy);
3590 		if ((len -= copy) == 0)
3591 			return csum;
3592 		offset += copy;
3593 		to     += copy;
3594 		pos	= copy;
3595 	}
3596 
3597 	if (!skb_frags_readable(skb))
3598 		return 0;
3599 
3600 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3601 		int end;
3602 
3603 		WARN_ON(start > offset + len);
3604 
3605 		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3606 		if ((copy = end - offset) > 0) {
3607 			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3608 			u32 p_off, p_len, copied;
3609 			struct page *p;
3610 			__wsum csum2;
3611 			u8 *vaddr;
3612 
3613 			if (copy > len)
3614 				copy = len;
3615 
3616 			skb_frag_foreach_page(frag,
3617 					      skb_frag_off(frag) + offset - start,
3618 					      copy, p, p_off, p_len, copied) {
3619 				vaddr = kmap_atomic(p);
3620 				csum2 = csum_partial_copy_nocheck(vaddr + p_off,
3621 								  to + copied,
3622 								  p_len);
3623 				kunmap_atomic(vaddr);
3624 				csum = csum_block_add(csum, csum2, pos);
3625 				pos += p_len;
3626 			}
3627 
3628 			if (!(len -= copy))
3629 				return csum;
3630 			offset += copy;
3631 			to     += copy;
3632 		}
3633 		start = end;
3634 	}
3635 
3636 	skb_walk_frags(skb, frag_iter) {
3637 		__wsum csum2;
3638 		int end;
3639 
3640 		WARN_ON(start > offset + len);
3641 
3642 		end = start + frag_iter->len;
3643 		if ((copy = end - offset) > 0) {
3644 			if (copy > len)
3645 				copy = len;
3646 			csum2 = skb_copy_and_csum_bits(frag_iter,
3647 						       offset - start,
3648 						       to, copy);
3649 			csum = csum_block_add(csum, csum2, pos);
3650 			if ((len -= copy) == 0)
3651 				return csum;
3652 			offset += copy;
3653 			to     += copy;
3654 			pos    += copy;
3655 		}
3656 		start = end;
3657 	}
3658 	BUG_ON(len);
3659 	return csum;
3660 }
3661 EXPORT_SYMBOL(skb_copy_and_csum_bits);
3662 
__skb_checksum_complete_head(struct sk_buff * skb,int len)3663 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
3664 {
3665 	__sum16 sum;
3666 
3667 	sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
3668 	/* See comments in __skb_checksum_complete(). */
3669 	if (likely(!sum)) {
3670 		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3671 		    !skb->csum_complete_sw)
3672 			netdev_rx_csum_fault(skb->dev, skb);
3673 	}
3674 	if (!skb_shared(skb))
3675 		skb->csum_valid = !sum;
3676 	return sum;
3677 }
3678 EXPORT_SYMBOL(__skb_checksum_complete_head);
3679 
3680 /* This function assumes skb->csum already holds pseudo header's checksum,
3681  * which has been changed from the hardware checksum, for example, by
3682  * __skb_checksum_validate_complete(). And, the original skb->csum must
3683  * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
3684  *
3685  * It returns non-zero if the recomputed checksum is still invalid, otherwise
3686  * zero. The new checksum is stored back into skb->csum unless the skb is
3687  * shared.
3688  */
__skb_checksum_complete(struct sk_buff * skb)3689 __sum16 __skb_checksum_complete(struct sk_buff *skb)
3690 {
3691 	__wsum csum;
3692 	__sum16 sum;
3693 
3694 	csum = skb_checksum(skb, 0, skb->len, 0);
3695 
3696 	sum = csum_fold(csum_add(skb->csum, csum));
3697 	/* This check is inverted, because we already knew the hardware
3698 	 * checksum is invalid before calling this function. So, if the
3699 	 * re-computed checksum is valid instead, then we have a mismatch
3700 	 * between the original skb->csum and skb_checksum(). This means either
3701 	 * the original hardware checksum is incorrect or we screw up skb->csum
3702 	 * when moving skb->data around.
3703 	 */
3704 	if (likely(!sum)) {
3705 		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3706 		    !skb->csum_complete_sw)
3707 			netdev_rx_csum_fault(skb->dev, skb);
3708 	}
3709 
3710 	if (!skb_shared(skb)) {
3711 		/* Save full packet checksum */
3712 		skb->csum = csum;
3713 		skb->ip_summed = CHECKSUM_COMPLETE;
3714 		skb->csum_complete_sw = 1;
3715 		skb->csum_valid = !sum;
3716 	}
3717 
3718 	return sum;
3719 }
3720 EXPORT_SYMBOL(__skb_checksum_complete);
3721 
warn_crc32c_csum_update(const void * buff,int len,__wsum sum)3722 static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
3723 {
3724 	net_warn_ratelimited(
3725 		"%s: attempt to compute crc32c without libcrc32c.ko\n",
3726 		__func__);
3727 	return 0;
3728 }
3729 
warn_crc32c_csum_combine(__wsum csum,__wsum csum2,int offset,int len)3730 static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
3731 				       int offset, int len)
3732 {
3733 	net_warn_ratelimited(
3734 		"%s: attempt to compute crc32c without libcrc32c.ko\n",
3735 		__func__);
3736 	return 0;
3737 }
3738 
3739 static const struct skb_checksum_ops default_crc32c_ops = {
3740 	.update  = warn_crc32c_csum_update,
3741 	.combine = warn_crc32c_csum_combine,
3742 };
3743 
3744 const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
3745 	&default_crc32c_ops;
3746 EXPORT_SYMBOL(crc32c_csum_stub);
3747 
3748  /**
3749  *	skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
3750  *	@from: source buffer
3751  *
3752  *	Calculates the amount of linear headroom needed in the 'to' skb passed
3753  *	into skb_zerocopy().
3754  */
3755 unsigned int
skb_zerocopy_headlen(const struct sk_buff * from)3756 skb_zerocopy_headlen(const struct sk_buff *from)
3757 {
3758 	unsigned int hlen = 0;
3759 
3760 	if (!from->head_frag ||
3761 	    skb_headlen(from) < L1_CACHE_BYTES ||
3762 	    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
3763 		hlen = skb_headlen(from);
3764 		if (!hlen)
3765 			hlen = from->len;
3766 	}
3767 
3768 	if (skb_has_frag_list(from))
3769 		hlen = from->len;
3770 
3771 	return hlen;
3772 }
3773 EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
3774 
3775 /**
3776  *	skb_zerocopy - Zero copy skb to skb
3777  *	@to: destination buffer
3778  *	@from: source buffer
3779  *	@len: number of bytes to copy from source buffer
3780  *	@hlen: size of linear headroom in destination buffer
3781  *
3782  *	Copies up to `len` bytes from `from` to `to` by creating references
3783  *	to the frags in the source buffer.
3784  *
3785  *	The `hlen` as calculated by skb_zerocopy_headlen() specifies the
3786  *	headroom in the `to` buffer.
3787  *
3788  *	Return value:
3789  *	0: everything is OK
3790  *	-ENOMEM: couldn't orphan frags of @from due to lack of memory
3791  *	-EFAULT: skb_copy_bits() found some problem with skb geometry
3792  */
3793 int
skb_zerocopy(struct sk_buff * to,struct sk_buff * from,int len,int hlen)3794 skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
3795 {
3796 	int i, j = 0;
3797 	int plen = 0; /* length of skb->head fragment */
3798 	int ret;
3799 	struct page *page;
3800 	unsigned int offset;
3801 
3802 	BUG_ON(!from->head_frag && !hlen);
3803 
3804 	/* dont bother with small payloads */
3805 	if (len <= skb_tailroom(to))
3806 		return skb_copy_bits(from, 0, skb_put(to, len), len);
3807 
3808 	if (hlen) {
3809 		ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
3810 		if (unlikely(ret))
3811 			return ret;
3812 		len -= hlen;
3813 	} else {
3814 		plen = min_t(int, skb_headlen(from), len);
3815 		if (plen) {
3816 			page = virt_to_head_page(from->head);
3817 			offset = from->data - (unsigned char *)page_address(page);
3818 			__skb_fill_netmem_desc(to, 0, page_to_netmem(page),
3819 					       offset, plen);
3820 			get_page(page);
3821 			j = 1;
3822 			len -= plen;
3823 		}
3824 	}
3825 
3826 	skb_len_add(to, len + plen);
3827 
3828 	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
3829 		skb_tx_error(from);
3830 		return -ENOMEM;
3831 	}
3832 	skb_zerocopy_clone(to, from, GFP_ATOMIC);
3833 
3834 	for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
3835 		int size;
3836 
3837 		if (!len)
3838 			break;
3839 		skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
3840 		size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
3841 					len);
3842 		skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
3843 		len -= size;
3844 		skb_frag_ref(to, j);
3845 		j++;
3846 	}
3847 	skb_shinfo(to)->nr_frags = j;
3848 
3849 	return 0;
3850 }
3851 EXPORT_SYMBOL_GPL(skb_zerocopy);
3852 
skb_copy_and_csum_dev(const struct sk_buff * skb,u8 * to)3853 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
3854 {
3855 	__wsum csum;
3856 	long csstart;
3857 
3858 	if (skb->ip_summed == CHECKSUM_PARTIAL)
3859 		csstart = skb_checksum_start_offset(skb);
3860 	else
3861 		csstart = skb_headlen(skb);
3862 
3863 	BUG_ON(csstart > skb_headlen(skb));
3864 
3865 	skb_copy_from_linear_data(skb, to, csstart);
3866 
3867 	csum = 0;
3868 	if (csstart != skb->len)
3869 		csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
3870 					      skb->len - csstart);
3871 
3872 	if (skb->ip_summed == CHECKSUM_PARTIAL) {
3873 		long csstuff = csstart + skb->csum_offset;
3874 
3875 		*((__sum16 *)(to + csstuff)) = csum_fold(csum);
3876 	}
3877 }
3878 EXPORT_SYMBOL(skb_copy_and_csum_dev);
3879 
3880 /**
3881  *	skb_dequeue - remove from the head of the queue
3882  *	@list: list to dequeue from
3883  *
3884  *	Remove the head of the list. The list lock is taken so the function
3885  *	may be used safely with other locking list functions. The head item is
3886  *	returned or %NULL if the list is empty.
3887  */
3888 
skb_dequeue(struct sk_buff_head * list)3889 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
3890 {
3891 	unsigned long flags;
3892 	struct sk_buff *result;
3893 
3894 	spin_lock_irqsave(&list->lock, flags);
3895 	result = __skb_dequeue(list);
3896 	spin_unlock_irqrestore(&list->lock, flags);
3897 	return result;
3898 }
3899 EXPORT_SYMBOL(skb_dequeue);
3900 
3901 /**
3902  *	skb_dequeue_tail - remove from the tail of the queue
3903  *	@list: list to dequeue from
3904  *
3905  *	Remove the tail of the list. The list lock is taken so the function
3906  *	may be used safely with other locking list functions. The tail item is
3907  *	returned or %NULL if the list is empty.
3908  */
skb_dequeue_tail(struct sk_buff_head * list)3909 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
3910 {
3911 	unsigned long flags;
3912 	struct sk_buff *result;
3913 
3914 	spin_lock_irqsave(&list->lock, flags);
3915 	result = __skb_dequeue_tail(list);
3916 	spin_unlock_irqrestore(&list->lock, flags);
3917 	return result;
3918 }
3919 EXPORT_SYMBOL(skb_dequeue_tail);
3920 
3921 /**
3922  *	skb_queue_purge_reason - empty a list
3923  *	@list: list to empty
3924  *	@reason: drop reason
3925  *
3926  *	Delete all buffers on an &sk_buff list. Each buffer is removed from
3927  *	the list and one reference dropped. This function takes the list
3928  *	lock and is atomic with respect to other list locking functions.
3929  */
skb_queue_purge_reason(struct sk_buff_head * list,enum skb_drop_reason reason)3930 void skb_queue_purge_reason(struct sk_buff_head *list,
3931 			    enum skb_drop_reason reason)
3932 {
3933 	struct sk_buff_head tmp;
3934 	unsigned long flags;
3935 
3936 	if (skb_queue_empty_lockless(list))
3937 		return;
3938 
3939 	__skb_queue_head_init(&tmp);
3940 
3941 	spin_lock_irqsave(&list->lock, flags);
3942 	skb_queue_splice_init(list, &tmp);
3943 	spin_unlock_irqrestore(&list->lock, flags);
3944 
3945 	__skb_queue_purge_reason(&tmp, reason);
3946 }
3947 EXPORT_SYMBOL(skb_queue_purge_reason);
3948 
3949 /**
3950  *	skb_rbtree_purge - empty a skb rbtree
3951  *	@root: root of the rbtree to empty
3952  *	Return value: the sum of truesizes of all purged skbs.
3953  *
3954  *	Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
3955  *	the list and one reference dropped. This function does not take
3956  *	any lock. Synchronization should be handled by the caller (e.g., TCP
3957  *	out-of-order queue is protected by the socket lock).
3958  */
skb_rbtree_purge(struct rb_root * root)3959 unsigned int skb_rbtree_purge(struct rb_root *root)
3960 {
3961 	struct rb_node *p = rb_first(root);
3962 	unsigned int sum = 0;
3963 
3964 	while (p) {
3965 		struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
3966 
3967 		p = rb_next(p);
3968 		rb_erase(&skb->rbnode, root);
3969 		sum += skb->truesize;
3970 		kfree_skb(skb);
3971 	}
3972 	return sum;
3973 }
3974 
skb_errqueue_purge(struct sk_buff_head * list)3975 void skb_errqueue_purge(struct sk_buff_head *list)
3976 {
3977 	struct sk_buff *skb, *next;
3978 	struct sk_buff_head kill;
3979 	unsigned long flags;
3980 
3981 	__skb_queue_head_init(&kill);
3982 
3983 	spin_lock_irqsave(&list->lock, flags);
3984 	skb_queue_walk_safe(list, skb, next) {
3985 		if (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ZEROCOPY ||
3986 		    SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING)
3987 			continue;
3988 		__skb_unlink(skb, list);
3989 		__skb_queue_tail(&kill, skb);
3990 	}
3991 	spin_unlock_irqrestore(&list->lock, flags);
3992 	__skb_queue_purge(&kill);
3993 }
3994 EXPORT_SYMBOL(skb_errqueue_purge);
3995 
3996 /**
3997  *	skb_queue_head - queue a buffer at the list head
3998  *	@list: list to use
3999  *	@newsk: buffer to queue
4000  *
4001  *	Queue a buffer at the start of the list. This function takes the
4002  *	list lock and can be used safely with other locking &sk_buff functions
4003  *	safely.
4004  *
4005  *	A buffer cannot be placed on two lists at the same time.
4006  */
skb_queue_head(struct sk_buff_head * list,struct sk_buff * newsk)4007 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
4008 {
4009 	unsigned long flags;
4010 
4011 	spin_lock_irqsave(&list->lock, flags);
4012 	__skb_queue_head(list, newsk);
4013 	spin_unlock_irqrestore(&list->lock, flags);
4014 }
4015 EXPORT_SYMBOL(skb_queue_head);
4016 
4017 /**
4018  *	skb_queue_tail - queue a buffer at the list tail
4019  *	@list: list to use
4020  *	@newsk: buffer to queue
4021  *
4022  *	Queue a buffer at the tail of the list. This function takes the
4023  *	list lock and can be used safely with other locking &sk_buff functions
4024  *	safely.
4025  *
4026  *	A buffer cannot be placed on two lists at the same time.
4027  */
skb_queue_tail(struct sk_buff_head * list,struct sk_buff * newsk)4028 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
4029 {
4030 	unsigned long flags;
4031 
4032 	spin_lock_irqsave(&list->lock, flags);
4033 	__skb_queue_tail(list, newsk);
4034 	spin_unlock_irqrestore(&list->lock, flags);
4035 }
4036 EXPORT_SYMBOL(skb_queue_tail);
4037 
4038 /**
4039  *	skb_unlink	-	remove a buffer from a list
4040  *	@skb: buffer to remove
4041  *	@list: list to use
4042  *
4043  *	Remove a packet from a list. The list locks are taken and this
4044  *	function is atomic with respect to other list locked calls
4045  *
4046  *	You must know what list the SKB is on.
4047  */
skb_unlink(struct sk_buff * skb,struct sk_buff_head * list)4048 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
4049 {
4050 	unsigned long flags;
4051 
4052 	spin_lock_irqsave(&list->lock, flags);
4053 	__skb_unlink(skb, list);
4054 	spin_unlock_irqrestore(&list->lock, flags);
4055 }
4056 EXPORT_SYMBOL(skb_unlink);
4057 
4058 /**
4059  *	skb_append	-	append a buffer
4060  *	@old: buffer to insert after
4061  *	@newsk: buffer to insert
4062  *	@list: list to use
4063  *
4064  *	Place a packet after a given packet in a list. The list locks are taken
4065  *	and this function is atomic with respect to other list locked calls.
4066  *	A buffer cannot be placed on two lists at the same time.
4067  */
skb_append(struct sk_buff * old,struct sk_buff * newsk,struct sk_buff_head * list)4068 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
4069 {
4070 	unsigned long flags;
4071 
4072 	spin_lock_irqsave(&list->lock, flags);
4073 	__skb_queue_after(list, old, newsk);
4074 	spin_unlock_irqrestore(&list->lock, flags);
4075 }
4076 EXPORT_SYMBOL(skb_append);
4077 
skb_split_inside_header(struct sk_buff * skb,struct sk_buff * skb1,const u32 len,const int pos)4078 static inline void skb_split_inside_header(struct sk_buff *skb,
4079 					   struct sk_buff* skb1,
4080 					   const u32 len, const int pos)
4081 {
4082 	int i;
4083 
4084 	skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
4085 					 pos - len);
4086 	/* And move data appendix as is. */
4087 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
4088 		skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
4089 
4090 	skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
4091 	skb1->unreadable	   = skb->unreadable;
4092 	skb_shinfo(skb)->nr_frags  = 0;
4093 	skb1->data_len		   = skb->data_len;
4094 	skb1->len		   += skb1->data_len;
4095 	skb->data_len		   = 0;
4096 	skb->len		   = len;
4097 	skb_set_tail_pointer(skb, len);
4098 }
4099 
skb_split_no_header(struct sk_buff * skb,struct sk_buff * skb1,const u32 len,int pos)4100 static inline void skb_split_no_header(struct sk_buff *skb,
4101 				       struct sk_buff* skb1,
4102 				       const u32 len, int pos)
4103 {
4104 	int i, k = 0;
4105 	const int nfrags = skb_shinfo(skb)->nr_frags;
4106 
4107 	skb_shinfo(skb)->nr_frags = 0;
4108 	skb1->len		  = skb1->data_len = skb->len - len;
4109 	skb->len		  = len;
4110 	skb->data_len		  = len - pos;
4111 
4112 	for (i = 0; i < nfrags; i++) {
4113 		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
4114 
4115 		if (pos + size > len) {
4116 			skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
4117 
4118 			if (pos < len) {
4119 				/* Split frag.
4120 				 * We have two variants in this case:
4121 				 * 1. Move all the frag to the second
4122 				 *    part, if it is possible. F.e.
4123 				 *    this approach is mandatory for TUX,
4124 				 *    where splitting is expensive.
4125 				 * 2. Split is accurately. We make this.
4126 				 */
4127 				skb_frag_ref(skb, i);
4128 				skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
4129 				skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
4130 				skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
4131 				skb_shinfo(skb)->nr_frags++;
4132 			}
4133 			k++;
4134 		} else
4135 			skb_shinfo(skb)->nr_frags++;
4136 		pos += size;
4137 	}
4138 	skb_shinfo(skb1)->nr_frags = k;
4139 
4140 	skb1->unreadable = skb->unreadable;
4141 }
4142 
4143 /**
4144  * skb_split - Split fragmented skb to two parts at length len.
4145  * @skb: the buffer to split
4146  * @skb1: the buffer to receive the second part
4147  * @len: new length for skb
4148  */
skb_split(struct sk_buff * skb,struct sk_buff * skb1,const u32 len)4149 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
4150 {
4151 	int pos = skb_headlen(skb);
4152 	const int zc_flags = SKBFL_SHARED_FRAG | SKBFL_PURE_ZEROCOPY;
4153 
4154 	skb_zcopy_downgrade_managed(skb);
4155 
4156 	skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & zc_flags;
4157 	skb_zerocopy_clone(skb1, skb, 0);
4158 	if (len < pos)	/* Split line is inside header. */
4159 		skb_split_inside_header(skb, skb1, len, pos);
4160 	else		/* Second chunk has no header, nothing to copy. */
4161 		skb_split_no_header(skb, skb1, len, pos);
4162 }
4163 EXPORT_SYMBOL(skb_split);
4164 
4165 /* Shifting from/to a cloned skb is a no-go.
4166  *
4167  * Caller cannot keep skb_shinfo related pointers past calling here!
4168  */
skb_prepare_for_shift(struct sk_buff * skb)4169 static int skb_prepare_for_shift(struct sk_buff *skb)
4170 {
4171 	return skb_unclone_keeptruesize(skb, GFP_ATOMIC);
4172 }
4173 
4174 /**
4175  * skb_shift - Shifts paged data partially from skb to another
4176  * @tgt: buffer into which tail data gets added
4177  * @skb: buffer from which the paged data comes from
4178  * @shiftlen: shift up to this many bytes
4179  *
4180  * Attempts to shift up to shiftlen worth of bytes, which may be less than
4181  * the length of the skb, from skb to tgt. Returns number bytes shifted.
4182  * It's up to caller to free skb if everything was shifted.
4183  *
4184  * If @tgt runs out of frags, the whole operation is aborted.
4185  *
4186  * Skb cannot include anything else but paged data while tgt is allowed
4187  * to have non-paged data as well.
4188  *
4189  * TODO: full sized shift could be optimized but that would need
4190  * specialized skb free'er to handle frags without up-to-date nr_frags.
4191  */
skb_shift(struct sk_buff * tgt,struct sk_buff * skb,int shiftlen)4192 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
4193 {
4194 	int from, to, merge, todo;
4195 	skb_frag_t *fragfrom, *fragto;
4196 
4197 	BUG_ON(shiftlen > skb->len);
4198 
4199 	if (skb_headlen(skb))
4200 		return 0;
4201 	if (skb_zcopy(tgt) || skb_zcopy(skb))
4202 		return 0;
4203 
4204 	DEBUG_NET_WARN_ON_ONCE(tgt->pp_recycle != skb->pp_recycle);
4205 	DEBUG_NET_WARN_ON_ONCE(skb_cmp_decrypted(tgt, skb));
4206 
4207 	todo = shiftlen;
4208 	from = 0;
4209 	to = skb_shinfo(tgt)->nr_frags;
4210 	fragfrom = &skb_shinfo(skb)->frags[from];
4211 
4212 	/* Actual merge is delayed until the point when we know we can
4213 	 * commit all, so that we don't have to undo partial changes
4214 	 */
4215 	if (!skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
4216 			      skb_frag_off(fragfrom))) {
4217 		merge = -1;
4218 	} else {
4219 		merge = to - 1;
4220 
4221 		todo -= skb_frag_size(fragfrom);
4222 		if (todo < 0) {
4223 			if (skb_prepare_for_shift(skb) ||
4224 			    skb_prepare_for_shift(tgt))
4225 				return 0;
4226 
4227 			/* All previous frag pointers might be stale! */
4228 			fragfrom = &skb_shinfo(skb)->frags[from];
4229 			fragto = &skb_shinfo(tgt)->frags[merge];
4230 
4231 			skb_frag_size_add(fragto, shiftlen);
4232 			skb_frag_size_sub(fragfrom, shiftlen);
4233 			skb_frag_off_add(fragfrom, shiftlen);
4234 
4235 			goto onlymerged;
4236 		}
4237 
4238 		from++;
4239 	}
4240 
4241 	/* Skip full, not-fitting skb to avoid expensive operations */
4242 	if ((shiftlen == skb->len) &&
4243 	    (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
4244 		return 0;
4245 
4246 	if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
4247 		return 0;
4248 
4249 	while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
4250 		if (to == MAX_SKB_FRAGS)
4251 			return 0;
4252 
4253 		fragfrom = &skb_shinfo(skb)->frags[from];
4254 		fragto = &skb_shinfo(tgt)->frags[to];
4255 
4256 		if (todo >= skb_frag_size(fragfrom)) {
4257 			*fragto = *fragfrom;
4258 			todo -= skb_frag_size(fragfrom);
4259 			from++;
4260 			to++;
4261 
4262 		} else {
4263 			__skb_frag_ref(fragfrom);
4264 			skb_frag_page_copy(fragto, fragfrom);
4265 			skb_frag_off_copy(fragto, fragfrom);
4266 			skb_frag_size_set(fragto, todo);
4267 
4268 			skb_frag_off_add(fragfrom, todo);
4269 			skb_frag_size_sub(fragfrom, todo);
4270 			todo = 0;
4271 
4272 			to++;
4273 			break;
4274 		}
4275 	}
4276 
4277 	/* Ready to "commit" this state change to tgt */
4278 	skb_shinfo(tgt)->nr_frags = to;
4279 
4280 	if (merge >= 0) {
4281 		fragfrom = &skb_shinfo(skb)->frags[0];
4282 		fragto = &skb_shinfo(tgt)->frags[merge];
4283 
4284 		skb_frag_size_add(fragto, skb_frag_size(fragfrom));
4285 		__skb_frag_unref(fragfrom, skb->pp_recycle);
4286 	}
4287 
4288 	/* Reposition in the original skb */
4289 	to = 0;
4290 	while (from < skb_shinfo(skb)->nr_frags)
4291 		skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
4292 	skb_shinfo(skb)->nr_frags = to;
4293 
4294 	BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
4295 
4296 onlymerged:
4297 	/* Most likely the tgt won't ever need its checksum anymore, skb on
4298 	 * the other hand might need it if it needs to be resent
4299 	 */
4300 	tgt->ip_summed = CHECKSUM_PARTIAL;
4301 	skb->ip_summed = CHECKSUM_PARTIAL;
4302 
4303 	skb_len_add(skb, -shiftlen);
4304 	skb_len_add(tgt, shiftlen);
4305 
4306 	return shiftlen;
4307 }
4308 
4309 /**
4310  * skb_prepare_seq_read - Prepare a sequential read of skb data
4311  * @skb: the buffer to read
4312  * @from: lower offset of data to be read
4313  * @to: upper offset of data to be read
4314  * @st: state variable
4315  *
4316  * Initializes the specified state variable. Must be called before
4317  * invoking skb_seq_read() for the first time.
4318  */
skb_prepare_seq_read(struct sk_buff * skb,unsigned int from,unsigned int to,struct skb_seq_state * st)4319 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
4320 			  unsigned int to, struct skb_seq_state *st)
4321 {
4322 	st->lower_offset = from;
4323 	st->upper_offset = to;
4324 	st->root_skb = st->cur_skb = skb;
4325 	st->frag_idx = st->stepped_offset = 0;
4326 	st->frag_data = NULL;
4327 	st->frag_off = 0;
4328 }
4329 EXPORT_SYMBOL(skb_prepare_seq_read);
4330 
4331 /**
4332  * skb_seq_read - Sequentially read skb data
4333  * @consumed: number of bytes consumed by the caller so far
4334  * @data: destination pointer for data to be returned
4335  * @st: state variable
4336  *
4337  * Reads a block of skb data at @consumed relative to the
4338  * lower offset specified to skb_prepare_seq_read(). Assigns
4339  * the head of the data block to @data and returns the length
4340  * of the block or 0 if the end of the skb data or the upper
4341  * offset has been reached.
4342  *
4343  * The caller is not required to consume all of the data
4344  * returned, i.e. @consumed is typically set to the number
4345  * of bytes already consumed and the next call to
4346  * skb_seq_read() will return the remaining part of the block.
4347  *
4348  * Note 1: The size of each block of data returned can be arbitrary,
4349  *       this limitation is the cost for zerocopy sequential
4350  *       reads of potentially non linear data.
4351  *
4352  * Note 2: Fragment lists within fragments are not implemented
4353  *       at the moment, state->root_skb could be replaced with
4354  *       a stack for this purpose.
4355  */
skb_seq_read(unsigned int consumed,const u8 ** data,struct skb_seq_state * st)4356 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
4357 			  struct skb_seq_state *st)
4358 {
4359 	unsigned int block_limit, abs_offset = consumed + st->lower_offset;
4360 	skb_frag_t *frag;
4361 
4362 	if (unlikely(abs_offset >= st->upper_offset)) {
4363 		if (st->frag_data) {
4364 			kunmap_atomic(st->frag_data);
4365 			st->frag_data = NULL;
4366 		}
4367 		return 0;
4368 	}
4369 
4370 next_skb:
4371 	block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
4372 
4373 	if (abs_offset < block_limit && !st->frag_data) {
4374 		*data = st->cur_skb->data + (abs_offset - st->stepped_offset);
4375 		return block_limit - abs_offset;
4376 	}
4377 
4378 	if (!skb_frags_readable(st->cur_skb))
4379 		return 0;
4380 
4381 	if (st->frag_idx == 0 && !st->frag_data)
4382 		st->stepped_offset += skb_headlen(st->cur_skb);
4383 
4384 	while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
4385 		unsigned int pg_idx, pg_off, pg_sz;
4386 
4387 		frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
4388 
4389 		pg_idx = 0;
4390 		pg_off = skb_frag_off(frag);
4391 		pg_sz = skb_frag_size(frag);
4392 
4393 		if (skb_frag_must_loop(skb_frag_page(frag))) {
4394 			pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;
4395 			pg_off = offset_in_page(pg_off + st->frag_off);
4396 			pg_sz = min_t(unsigned int, pg_sz - st->frag_off,
4397 						    PAGE_SIZE - pg_off);
4398 		}
4399 
4400 		block_limit = pg_sz + st->stepped_offset;
4401 		if (abs_offset < block_limit) {
4402 			if (!st->frag_data)
4403 				st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);
4404 
4405 			*data = (u8 *)st->frag_data + pg_off +
4406 				(abs_offset - st->stepped_offset);
4407 
4408 			return block_limit - abs_offset;
4409 		}
4410 
4411 		if (st->frag_data) {
4412 			kunmap_atomic(st->frag_data);
4413 			st->frag_data = NULL;
4414 		}
4415 
4416 		st->stepped_offset += pg_sz;
4417 		st->frag_off += pg_sz;
4418 		if (st->frag_off == skb_frag_size(frag)) {
4419 			st->frag_off = 0;
4420 			st->frag_idx++;
4421 		}
4422 	}
4423 
4424 	if (st->frag_data) {
4425 		kunmap_atomic(st->frag_data);
4426 		st->frag_data = NULL;
4427 	}
4428 
4429 	if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
4430 		st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
4431 		st->frag_idx = 0;
4432 		goto next_skb;
4433 	} else if (st->cur_skb->next) {
4434 		st->cur_skb = st->cur_skb->next;
4435 		st->frag_idx = 0;
4436 		goto next_skb;
4437 	}
4438 
4439 	return 0;
4440 }
4441 EXPORT_SYMBOL(skb_seq_read);
4442 
4443 /**
4444  * skb_abort_seq_read - Abort a sequential read of skb data
4445  * @st: state variable
4446  *
4447  * Must be called if skb_seq_read() was not called until it
4448  * returned 0.
4449  */
skb_abort_seq_read(struct skb_seq_state * st)4450 void skb_abort_seq_read(struct skb_seq_state *st)
4451 {
4452 	if (st->frag_data)
4453 		kunmap_atomic(st->frag_data);
4454 }
4455 EXPORT_SYMBOL(skb_abort_seq_read);
4456 
4457 /**
4458  * skb_copy_seq_read() - copy from a skb_seq_state to a buffer
4459  * @st: source skb_seq_state
4460  * @offset: offset in source
4461  * @to: destination buffer
4462  * @len: number of bytes to copy
4463  *
4464  * Copy @len bytes from @offset bytes into the source @st to the destination
4465  * buffer @to. `offset` should increase (or be unchanged) with each subsequent
4466  * call to this function. If offset needs to decrease from the previous use `st`
4467  * should be reset first.
4468  *
4469  * Return: 0 on success or -EINVAL if the copy ended early
4470  */
skb_copy_seq_read(struct skb_seq_state * st,int offset,void * to,int len)4471 int skb_copy_seq_read(struct skb_seq_state *st, int offset, void *to, int len)
4472 {
4473 	const u8 *data;
4474 	u32 sqlen;
4475 
4476 	for (;;) {
4477 		sqlen = skb_seq_read(offset, &data, st);
4478 		if (sqlen == 0)
4479 			return -EINVAL;
4480 		if (sqlen >= len) {
4481 			memcpy(to, data, len);
4482 			return 0;
4483 		}
4484 		memcpy(to, data, sqlen);
4485 		to += sqlen;
4486 		offset += sqlen;
4487 		len -= sqlen;
4488 	}
4489 }
4490 EXPORT_SYMBOL(skb_copy_seq_read);
4491 
4492 #define TS_SKB_CB(state)	((struct skb_seq_state *) &((state)->cb))
4493 
skb_ts_get_next_block(unsigned int offset,const u8 ** text,struct ts_config * conf,struct ts_state * state)4494 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
4495 					  struct ts_config *conf,
4496 					  struct ts_state *state)
4497 {
4498 	return skb_seq_read(offset, text, TS_SKB_CB(state));
4499 }
4500 
skb_ts_finish(struct ts_config * conf,struct ts_state * state)4501 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
4502 {
4503 	skb_abort_seq_read(TS_SKB_CB(state));
4504 }
4505 
4506 /**
4507  * skb_find_text - Find a text pattern in skb data
4508  * @skb: the buffer to look in
4509  * @from: search offset
4510  * @to: search limit
4511  * @config: textsearch configuration
4512  *
4513  * Finds a pattern in the skb data according to the specified
4514  * textsearch configuration. Use textsearch_next() to retrieve
4515  * subsequent occurrences of the pattern. Returns the offset
4516  * to the first occurrence or UINT_MAX if no match was found.
4517  */
skb_find_text(struct sk_buff * skb,unsigned int from,unsigned int to,struct ts_config * config)4518 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
4519 			   unsigned int to, struct ts_config *config)
4520 {
4521 	unsigned int patlen = config->ops->get_pattern_len(config);
4522 	struct ts_state state;
4523 	unsigned int ret;
4524 
4525 	BUILD_BUG_ON(sizeof(struct skb_seq_state) > sizeof(state.cb));
4526 
4527 	config->get_next_block = skb_ts_get_next_block;
4528 	config->finish = skb_ts_finish;
4529 
4530 	skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
4531 
4532 	ret = textsearch_find(config, &state);
4533 	return (ret + patlen <= to - from ? ret : UINT_MAX);
4534 }
4535 EXPORT_SYMBOL(skb_find_text);
4536 
skb_append_pagefrags(struct sk_buff * skb,struct page * page,int offset,size_t size,size_t max_frags)4537 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
4538 			 int offset, size_t size, size_t max_frags)
4539 {
4540 	int i = skb_shinfo(skb)->nr_frags;
4541 
4542 	if (skb_can_coalesce(skb, i, page, offset)) {
4543 		skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
4544 	} else if (i < max_frags) {
4545 		skb_zcopy_downgrade_managed(skb);
4546 		get_page(page);
4547 		skb_fill_page_desc_noacc(skb, i, page, offset, size);
4548 	} else {
4549 		return -EMSGSIZE;
4550 	}
4551 
4552 	return 0;
4553 }
4554 EXPORT_SYMBOL_GPL(skb_append_pagefrags);
4555 
4556 /**
4557  *	skb_pull_rcsum - pull skb and update receive checksum
4558  *	@skb: buffer to update
4559  *	@len: length of data pulled
4560  *
4561  *	This function performs an skb_pull on the packet and updates
4562  *	the CHECKSUM_COMPLETE checksum.  It should be used on
4563  *	receive path processing instead of skb_pull unless you know
4564  *	that the checksum difference is zero (e.g., a valid IP header)
4565  *	or you are setting ip_summed to CHECKSUM_NONE.
4566  */
skb_pull_rcsum(struct sk_buff * skb,unsigned int len)4567 void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
4568 {
4569 	unsigned char *data = skb->data;
4570 
4571 	BUG_ON(len > skb->len);
4572 	__skb_pull(skb, len);
4573 	skb_postpull_rcsum(skb, data, len);
4574 	return skb->data;
4575 }
4576 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
4577 
skb_head_frag_to_page_desc(struct sk_buff * frag_skb)4578 static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
4579 {
4580 	skb_frag_t head_frag;
4581 	struct page *page;
4582 
4583 	page = virt_to_head_page(frag_skb->head);
4584 	skb_frag_fill_page_desc(&head_frag, page, frag_skb->data -
4585 				(unsigned char *)page_address(page),
4586 				skb_headlen(frag_skb));
4587 	return head_frag;
4588 }
4589 
skb_segment_list(struct sk_buff * skb,netdev_features_t features,unsigned int offset)4590 struct sk_buff *skb_segment_list(struct sk_buff *skb,
4591 				 netdev_features_t features,
4592 				 unsigned int offset)
4593 {
4594 	struct sk_buff *list_skb = skb_shinfo(skb)->frag_list;
4595 	unsigned int tnl_hlen = skb_tnl_header_len(skb);
4596 	unsigned int delta_truesize = 0;
4597 	unsigned int delta_len = 0;
4598 	struct sk_buff *tail = NULL;
4599 	struct sk_buff *nskb, *tmp;
4600 	int len_diff, err;
4601 
4602 	skb_push(skb, -skb_network_offset(skb) + offset);
4603 
4604 	/* Ensure the head is writeable before touching the shared info */
4605 	err = skb_unclone(skb, GFP_ATOMIC);
4606 	if (err)
4607 		goto err_linearize;
4608 
4609 	skb_shinfo(skb)->frag_list = NULL;
4610 
4611 	while (list_skb) {
4612 		nskb = list_skb;
4613 		list_skb = list_skb->next;
4614 
4615 		err = 0;
4616 		delta_truesize += nskb->truesize;
4617 		if (skb_shared(nskb)) {
4618 			tmp = skb_clone(nskb, GFP_ATOMIC);
4619 			if (tmp) {
4620 				consume_skb(nskb);
4621 				nskb = tmp;
4622 				err = skb_unclone(nskb, GFP_ATOMIC);
4623 			} else {
4624 				err = -ENOMEM;
4625 			}
4626 		}
4627 
4628 		if (!tail)
4629 			skb->next = nskb;
4630 		else
4631 			tail->next = nskb;
4632 
4633 		if (unlikely(err)) {
4634 			nskb->next = list_skb;
4635 			goto err_linearize;
4636 		}
4637 
4638 		tail = nskb;
4639 
4640 		delta_len += nskb->len;
4641 
4642 		skb_push(nskb, -skb_network_offset(nskb) + offset);
4643 
4644 		skb_release_head_state(nskb);
4645 		len_diff = skb_network_header_len(nskb) - skb_network_header_len(skb);
4646 		__copy_skb_header(nskb, skb);
4647 
4648 		skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
4649 		nskb->transport_header += len_diff;
4650 		skb_copy_from_linear_data_offset(skb, -tnl_hlen,
4651 						 nskb->data - tnl_hlen,
4652 						 offset + tnl_hlen);
4653 
4654 		if (skb_needs_linearize(nskb, features) &&
4655 		    __skb_linearize(nskb))
4656 			goto err_linearize;
4657 	}
4658 
4659 	skb->truesize = skb->truesize - delta_truesize;
4660 	skb->data_len = skb->data_len - delta_len;
4661 	skb->len = skb->len - delta_len;
4662 
4663 	skb_gso_reset(skb);
4664 
4665 	skb->prev = tail;
4666 
4667 	if (skb_needs_linearize(skb, features) &&
4668 	    __skb_linearize(skb))
4669 		goto err_linearize;
4670 
4671 	skb_get(skb);
4672 
4673 	return skb;
4674 
4675 err_linearize:
4676 	kfree_skb_list(skb->next);
4677 	skb->next = NULL;
4678 	return ERR_PTR(-ENOMEM);
4679 }
4680 EXPORT_SYMBOL_GPL(skb_segment_list);
4681 
4682 /**
4683  *	skb_segment - Perform protocol segmentation on skb.
4684  *	@head_skb: buffer to segment
4685  *	@features: features for the output path (see dev->features)
4686  *
4687  *	This function performs segmentation on the given skb.  It returns
4688  *	a pointer to the first in a list of new skbs for the segments.
4689  *	In case of error it returns ERR_PTR(err).
4690  */
skb_segment(struct sk_buff * head_skb,netdev_features_t features)4691 struct sk_buff *skb_segment(struct sk_buff *head_skb,
4692 			    netdev_features_t features)
4693 {
4694 	struct sk_buff *segs = NULL;
4695 	struct sk_buff *tail = NULL;
4696 	struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
4697 	unsigned int mss = skb_shinfo(head_skb)->gso_size;
4698 	unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
4699 	unsigned int offset = doffset;
4700 	unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
4701 	unsigned int partial_segs = 0;
4702 	unsigned int headroom;
4703 	unsigned int len = head_skb->len;
4704 	struct sk_buff *frag_skb;
4705 	skb_frag_t *frag;
4706 	__be16 proto;
4707 	bool csum, sg;
4708 	int err = -ENOMEM;
4709 	int i = 0;
4710 	int nfrags, pos;
4711 
4712 	if ((skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY) &&
4713 	    mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb)) {
4714 		struct sk_buff *check_skb;
4715 
4716 		for (check_skb = list_skb; check_skb; check_skb = check_skb->next) {
4717 			if (skb_headlen(check_skb) && !check_skb->head_frag) {
4718 				/* gso_size is untrusted, and we have a frag_list with
4719 				 * a linear non head_frag item.
4720 				 *
4721 				 * If head_skb's headlen does not fit requested gso_size,
4722 				 * it means that the frag_list members do NOT terminate
4723 				 * on exact gso_size boundaries. Hence we cannot perform
4724 				 * skb_frag_t page sharing. Therefore we must fallback to
4725 				 * copying the frag_list skbs; we do so by disabling SG.
4726 				 */
4727 				features &= ~NETIF_F_SG;
4728 				break;
4729 			}
4730 		}
4731 	}
4732 
4733 	__skb_push(head_skb, doffset);
4734 	proto = skb_network_protocol(head_skb, NULL);
4735 	if (unlikely(!proto))
4736 		return ERR_PTR(-EINVAL);
4737 
4738 	sg = !!(features & NETIF_F_SG);
4739 	csum = !!can_checksum_protocol(features, proto);
4740 
4741 	if (sg && csum && (mss != GSO_BY_FRAGS))  {
4742 		if (!(features & NETIF_F_GSO_PARTIAL)) {
4743 			struct sk_buff *iter;
4744 			unsigned int frag_len;
4745 
4746 			if (!list_skb ||
4747 			    !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
4748 				goto normal;
4749 
4750 			/* If we get here then all the required
4751 			 * GSO features except frag_list are supported.
4752 			 * Try to split the SKB to multiple GSO SKBs
4753 			 * with no frag_list.
4754 			 * Currently we can do that only when the buffers don't
4755 			 * have a linear part and all the buffers except
4756 			 * the last are of the same length.
4757 			 */
4758 			frag_len = list_skb->len;
4759 			skb_walk_frags(head_skb, iter) {
4760 				if (frag_len != iter->len && iter->next)
4761 					goto normal;
4762 				if (skb_headlen(iter) && !iter->head_frag)
4763 					goto normal;
4764 
4765 				len -= iter->len;
4766 			}
4767 
4768 			if (len != frag_len)
4769 				goto normal;
4770 		}
4771 
4772 		/* GSO partial only requires that we trim off any excess that
4773 		 * doesn't fit into an MSS sized block, so take care of that
4774 		 * now.
4775 		 * Cap len to not accidentally hit GSO_BY_FRAGS.
4776 		 */
4777 		partial_segs = min(len, GSO_BY_FRAGS - 1) / mss;
4778 		if (partial_segs > 1)
4779 			mss *= partial_segs;
4780 		else
4781 			partial_segs = 0;
4782 	}
4783 
4784 normal:
4785 	headroom = skb_headroom(head_skb);
4786 	pos = skb_headlen(head_skb);
4787 
4788 	if (skb_orphan_frags(head_skb, GFP_ATOMIC))
4789 		return ERR_PTR(-ENOMEM);
4790 
4791 	nfrags = skb_shinfo(head_skb)->nr_frags;
4792 	frag = skb_shinfo(head_skb)->frags;
4793 	frag_skb = head_skb;
4794 
4795 	do {
4796 		struct sk_buff *nskb;
4797 		skb_frag_t *nskb_frag;
4798 		int hsize;
4799 		int size;
4800 
4801 		if (unlikely(mss == GSO_BY_FRAGS)) {
4802 			len = list_skb->len;
4803 		} else {
4804 			len = head_skb->len - offset;
4805 			if (len > mss)
4806 				len = mss;
4807 		}
4808 
4809 		hsize = skb_headlen(head_skb) - offset;
4810 
4811 		if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
4812 		    (skb_headlen(list_skb) == len || sg)) {
4813 			BUG_ON(skb_headlen(list_skb) > len);
4814 
4815 			nskb = skb_clone(list_skb, GFP_ATOMIC);
4816 			if (unlikely(!nskb))
4817 				goto err;
4818 
4819 			i = 0;
4820 			nfrags = skb_shinfo(list_skb)->nr_frags;
4821 			frag = skb_shinfo(list_skb)->frags;
4822 			frag_skb = list_skb;
4823 			pos += skb_headlen(list_skb);
4824 
4825 			while (pos < offset + len) {
4826 				BUG_ON(i >= nfrags);
4827 
4828 				size = skb_frag_size(frag);
4829 				if (pos + size > offset + len)
4830 					break;
4831 
4832 				i++;
4833 				pos += size;
4834 				frag++;
4835 			}
4836 
4837 			list_skb = list_skb->next;
4838 
4839 			if (unlikely(pskb_trim(nskb, len))) {
4840 				kfree_skb(nskb);
4841 				goto err;
4842 			}
4843 
4844 			hsize = skb_end_offset(nskb);
4845 			if (skb_cow_head(nskb, doffset + headroom)) {
4846 				kfree_skb(nskb);
4847 				goto err;
4848 			}
4849 
4850 			nskb->truesize += skb_end_offset(nskb) - hsize;
4851 			skb_release_head_state(nskb);
4852 			__skb_push(nskb, doffset);
4853 		} else {
4854 			if (hsize < 0)
4855 				hsize = 0;
4856 			if (hsize > len || !sg)
4857 				hsize = len;
4858 
4859 			nskb = __alloc_skb(hsize + doffset + headroom,
4860 					   GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
4861 					   NUMA_NO_NODE);
4862 
4863 			if (unlikely(!nskb))
4864 				goto err;
4865 
4866 			skb_reserve(nskb, headroom);
4867 			__skb_put(nskb, doffset);
4868 		}
4869 
4870 		if (segs)
4871 			tail->next = nskb;
4872 		else
4873 			segs = nskb;
4874 		tail = nskb;
4875 
4876 		__copy_skb_header(nskb, head_skb);
4877 
4878 		skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
4879 		skb_reset_mac_len(nskb);
4880 
4881 		skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
4882 						 nskb->data - tnl_hlen,
4883 						 doffset + tnl_hlen);
4884 
4885 		if (nskb->len == len + doffset)
4886 			goto perform_csum_check;
4887 
4888 		if (!sg) {
4889 			if (!csum) {
4890 				if (!nskb->remcsum_offload)
4891 					nskb->ip_summed = CHECKSUM_NONE;
4892 				SKB_GSO_CB(nskb)->csum =
4893 					skb_copy_and_csum_bits(head_skb, offset,
4894 							       skb_put(nskb,
4895 								       len),
4896 							       len);
4897 				SKB_GSO_CB(nskb)->csum_start =
4898 					skb_headroom(nskb) + doffset;
4899 			} else {
4900 				if (skb_copy_bits(head_skb, offset, skb_put(nskb, len), len))
4901 					goto err;
4902 			}
4903 			continue;
4904 		}
4905 
4906 		nskb_frag = skb_shinfo(nskb)->frags;
4907 
4908 		skb_copy_from_linear_data_offset(head_skb, offset,
4909 						 skb_put(nskb, hsize), hsize);
4910 
4911 		skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
4912 					   SKBFL_SHARED_FRAG;
4913 
4914 		if (skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
4915 			goto err;
4916 
4917 		while (pos < offset + len) {
4918 			if (i >= nfrags) {
4919 				if (skb_orphan_frags(list_skb, GFP_ATOMIC) ||
4920 				    skb_zerocopy_clone(nskb, list_skb,
4921 						       GFP_ATOMIC))
4922 					goto err;
4923 
4924 				i = 0;
4925 				nfrags = skb_shinfo(list_skb)->nr_frags;
4926 				frag = skb_shinfo(list_skb)->frags;
4927 				frag_skb = list_skb;
4928 				if (!skb_headlen(list_skb)) {
4929 					BUG_ON(!nfrags);
4930 				} else {
4931 					BUG_ON(!list_skb->head_frag);
4932 
4933 					/* to make room for head_frag. */
4934 					i--;
4935 					frag--;
4936 				}
4937 
4938 				list_skb = list_skb->next;
4939 			}
4940 
4941 			if (unlikely(skb_shinfo(nskb)->nr_frags >=
4942 				     MAX_SKB_FRAGS)) {
4943 				net_warn_ratelimited(
4944 					"skb_segment: too many frags: %u %u\n",
4945 					pos, mss);
4946 				err = -EINVAL;
4947 				goto err;
4948 			}
4949 
4950 			*nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
4951 			__skb_frag_ref(nskb_frag);
4952 			size = skb_frag_size(nskb_frag);
4953 
4954 			if (pos < offset) {
4955 				skb_frag_off_add(nskb_frag, offset - pos);
4956 				skb_frag_size_sub(nskb_frag, offset - pos);
4957 			}
4958 
4959 			skb_shinfo(nskb)->nr_frags++;
4960 
4961 			if (pos + size <= offset + len) {
4962 				i++;
4963 				frag++;
4964 				pos += size;
4965 			} else {
4966 				skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
4967 				goto skip_fraglist;
4968 			}
4969 
4970 			nskb_frag++;
4971 		}
4972 
4973 skip_fraglist:
4974 		nskb->data_len = len - hsize;
4975 		nskb->len += nskb->data_len;
4976 		nskb->truesize += nskb->data_len;
4977 
4978 perform_csum_check:
4979 		if (!csum) {
4980 			if (skb_has_shared_frag(nskb) &&
4981 			    __skb_linearize(nskb))
4982 				goto err;
4983 
4984 			if (!nskb->remcsum_offload)
4985 				nskb->ip_summed = CHECKSUM_NONE;
4986 			SKB_GSO_CB(nskb)->csum =
4987 				skb_checksum(nskb, doffset,
4988 					     nskb->len - doffset, 0);
4989 			SKB_GSO_CB(nskb)->csum_start =
4990 				skb_headroom(nskb) + doffset;
4991 		}
4992 	} while ((offset += len) < head_skb->len);
4993 
4994 	/* Some callers want to get the end of the list.
4995 	 * Put it in segs->prev to avoid walking the list.
4996 	 * (see validate_xmit_skb_list() for example)
4997 	 */
4998 	segs->prev = tail;
4999 
5000 	if (partial_segs) {
5001 		struct sk_buff *iter;
5002 		int type = skb_shinfo(head_skb)->gso_type;
5003 		unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
5004 
5005 		/* Update type to add partial and then remove dodgy if set */
5006 		type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
5007 		type &= ~SKB_GSO_DODGY;
5008 
5009 		/* Update GSO info and prepare to start updating headers on
5010 		 * our way back down the stack of protocols.
5011 		 */
5012 		for (iter = segs; iter; iter = iter->next) {
5013 			skb_shinfo(iter)->gso_size = gso_size;
5014 			skb_shinfo(iter)->gso_segs = partial_segs;
5015 			skb_shinfo(iter)->gso_type = type;
5016 			SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
5017 		}
5018 
5019 		if (tail->len - doffset <= gso_size)
5020 			skb_shinfo(tail)->gso_size = 0;
5021 		else if (tail != segs)
5022 			skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
5023 	}
5024 
5025 	/* Following permits correct backpressure, for protocols
5026 	 * using skb_set_owner_w().
5027 	 * Idea is to tranfert ownership from head_skb to last segment.
5028 	 */
5029 	if (head_skb->destructor == sock_wfree) {
5030 		swap(tail->truesize, head_skb->truesize);
5031 		swap(tail->destructor, head_skb->destructor);
5032 		swap(tail->sk, head_skb->sk);
5033 	}
5034 	return segs;
5035 
5036 err:
5037 	kfree_skb_list(segs);
5038 	return ERR_PTR(err);
5039 }
5040 EXPORT_SYMBOL_GPL(skb_segment);
5041 
5042 #ifdef CONFIG_SKB_EXTENSIONS
5043 #define SKB_EXT_ALIGN_VALUE	8
5044 #define SKB_EXT_CHUNKSIZEOF(x)	(ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
5045 
5046 static const u8 skb_ext_type_len[] = {
5047 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
5048 	[SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
5049 #endif
5050 #ifdef CONFIG_XFRM
5051 	[SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
5052 #endif
5053 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
5054 	[TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
5055 #endif
5056 #if IS_ENABLED(CONFIG_MPTCP)
5057 	[SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
5058 #endif
5059 #if IS_ENABLED(CONFIG_MCTP_FLOWS)
5060 	[SKB_EXT_MCTP] = SKB_EXT_CHUNKSIZEOF(struct mctp_flow),
5061 #endif
5062 };
5063 
skb_ext_total_length(void)5064 static __always_inline unsigned int skb_ext_total_length(void)
5065 {
5066 	unsigned int l = SKB_EXT_CHUNKSIZEOF(struct skb_ext);
5067 	int i;
5068 
5069 	for (i = 0; i < ARRAY_SIZE(skb_ext_type_len); i++)
5070 		l += skb_ext_type_len[i];
5071 
5072 	return l;
5073 }
5074 
skb_extensions_init(void)5075 static void skb_extensions_init(void)
5076 {
5077 	BUILD_BUG_ON(SKB_EXT_NUM >= 8);
5078 #if !IS_ENABLED(CONFIG_KCOV_INSTRUMENT_ALL)
5079 	BUILD_BUG_ON(skb_ext_total_length() > 255);
5080 #endif
5081 
5082 	skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
5083 					     SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
5084 					     0,
5085 					     SLAB_HWCACHE_ALIGN|SLAB_PANIC,
5086 					     NULL);
5087 }
5088 #else
skb_extensions_init(void)5089 static void skb_extensions_init(void) {}
5090 #endif
5091 
5092 /* The SKB kmem_cache slab is critical for network performance.  Never
5093  * merge/alias the slab with similar sized objects.  This avoids fragmentation
5094  * that hurts performance of kmem_cache_{alloc,free}_bulk APIs.
5095  */
5096 #ifndef CONFIG_SLUB_TINY
5097 #define FLAG_SKB_NO_MERGE	SLAB_NO_MERGE
5098 #else /* CONFIG_SLUB_TINY - simple loop in kmem_cache_alloc_bulk */
5099 #define FLAG_SKB_NO_MERGE	0
5100 #endif
5101 
skb_init(void)5102 void __init skb_init(void)
5103 {
5104 	net_hotdata.skbuff_cache = kmem_cache_create_usercopy("skbuff_head_cache",
5105 					      sizeof(struct sk_buff),
5106 					      0,
5107 					      SLAB_HWCACHE_ALIGN|SLAB_PANIC|
5108 						FLAG_SKB_NO_MERGE,
5109 					      offsetof(struct sk_buff, cb),
5110 					      sizeof_field(struct sk_buff, cb),
5111 					      NULL);
5112 	net_hotdata.skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
5113 						sizeof(struct sk_buff_fclones),
5114 						0,
5115 						SLAB_HWCACHE_ALIGN|SLAB_PANIC,
5116 						NULL);
5117 	/* usercopy should only access first SKB_SMALL_HEAD_HEADROOM bytes.
5118 	 * struct skb_shared_info is located at the end of skb->head,
5119 	 * and should not be copied to/from user.
5120 	 */
5121 	net_hotdata.skb_small_head_cache = kmem_cache_create_usercopy("skbuff_small_head",
5122 						SKB_SMALL_HEAD_CACHE_SIZE,
5123 						0,
5124 						SLAB_HWCACHE_ALIGN | SLAB_PANIC,
5125 						0,
5126 						SKB_SMALL_HEAD_HEADROOM,
5127 						NULL);
5128 	skb_extensions_init();
5129 }
5130 
5131 static int
__skb_to_sgvec(struct sk_buff * skb,struct scatterlist * sg,int offset,int len,unsigned int recursion_level)5132 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
5133 	       unsigned int recursion_level)
5134 {
5135 	int start = skb_headlen(skb);
5136 	int i, copy = start - offset;
5137 	struct sk_buff *frag_iter;
5138 	int elt = 0;
5139 
5140 	if (unlikely(recursion_level >= 24))
5141 		return -EMSGSIZE;
5142 
5143 	if (copy > 0) {
5144 		if (copy > len)
5145 			copy = len;
5146 		sg_set_buf(sg, skb->data + offset, copy);
5147 		elt++;
5148 		if ((len -= copy) == 0)
5149 			return elt;
5150 		offset += copy;
5151 	}
5152 
5153 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
5154 		int end;
5155 
5156 		WARN_ON(start > offset + len);
5157 
5158 		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
5159 		if ((copy = end - offset) > 0) {
5160 			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
5161 			if (unlikely(elt && sg_is_last(&sg[elt - 1])))
5162 				return -EMSGSIZE;
5163 
5164 			if (copy > len)
5165 				copy = len;
5166 			sg_set_page(&sg[elt], skb_frag_page(frag), copy,
5167 				    skb_frag_off(frag) + offset - start);
5168 			elt++;
5169 			if (!(len -= copy))
5170 				return elt;
5171 			offset += copy;
5172 		}
5173 		start = end;
5174 	}
5175 
5176 	skb_walk_frags(skb, frag_iter) {
5177 		int end, ret;
5178 
5179 		WARN_ON(start > offset + len);
5180 
5181 		end = start + frag_iter->len;
5182 		if ((copy = end - offset) > 0) {
5183 			if (unlikely(elt && sg_is_last(&sg[elt - 1])))
5184 				return -EMSGSIZE;
5185 
5186 			if (copy > len)
5187 				copy = len;
5188 			ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
5189 					      copy, recursion_level + 1);
5190 			if (unlikely(ret < 0))
5191 				return ret;
5192 			elt += ret;
5193 			if ((len -= copy) == 0)
5194 				return elt;
5195 			offset += copy;
5196 		}
5197 		start = end;
5198 	}
5199 	BUG_ON(len);
5200 	return elt;
5201 }
5202 
5203 /**
5204  *	skb_to_sgvec - Fill a scatter-gather list from a socket buffer
5205  *	@skb: Socket buffer containing the buffers to be mapped
5206  *	@sg: The scatter-gather list to map into
5207  *	@offset: The offset into the buffer's contents to start mapping
5208  *	@len: Length of buffer space to be mapped
5209  *
5210  *	Fill the specified scatter-gather list with mappings/pointers into a
5211  *	region of the buffer space attached to a socket buffer. Returns either
5212  *	the number of scatterlist items used, or -EMSGSIZE if the contents
5213  *	could not fit.
5214  */
skb_to_sgvec(struct sk_buff * skb,struct scatterlist * sg,int offset,int len)5215 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
5216 {
5217 	int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
5218 
5219 	if (nsg <= 0)
5220 		return nsg;
5221 
5222 	sg_mark_end(&sg[nsg - 1]);
5223 
5224 	return nsg;
5225 }
5226 EXPORT_SYMBOL_GPL(skb_to_sgvec);
5227 
5228 /* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
5229  * sglist without mark the sg which contain last skb data as the end.
5230  * So the caller can mannipulate sg list as will when padding new data after
5231  * the first call without calling sg_unmark_end to expend sg list.
5232  *
5233  * Scenario to use skb_to_sgvec_nomark:
5234  * 1. sg_init_table
5235  * 2. skb_to_sgvec_nomark(payload1)
5236  * 3. skb_to_sgvec_nomark(payload2)
5237  *
5238  * This is equivalent to:
5239  * 1. sg_init_table
5240  * 2. skb_to_sgvec(payload1)
5241  * 3. sg_unmark_end
5242  * 4. skb_to_sgvec(payload2)
5243  *
5244  * When mapping multiple payload conditionally, skb_to_sgvec_nomark
5245  * is more preferable.
5246  */
skb_to_sgvec_nomark(struct sk_buff * skb,struct scatterlist * sg,int offset,int len)5247 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
5248 			int offset, int len)
5249 {
5250 	return __skb_to_sgvec(skb, sg, offset, len, 0);
5251 }
5252 EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
5253 
5254 
5255 
5256 /**
5257  *	skb_cow_data - Check that a socket buffer's data buffers are writable
5258  *	@skb: The socket buffer to check.
5259  *	@tailbits: Amount of trailing space to be added
5260  *	@trailer: Returned pointer to the skb where the @tailbits space begins
5261  *
5262  *	Make sure that the data buffers attached to a socket buffer are
5263  *	writable. If they are not, private copies are made of the data buffers
5264  *	and the socket buffer is set to use these instead.
5265  *
5266  *	If @tailbits is given, make sure that there is space to write @tailbits
5267  *	bytes of data beyond current end of socket buffer.  @trailer will be
5268  *	set to point to the skb in which this space begins.
5269  *
5270  *	The number of scatterlist elements required to completely map the
5271  *	COW'd and extended socket buffer will be returned.
5272  */
skb_cow_data(struct sk_buff * skb,int tailbits,struct sk_buff ** trailer)5273 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
5274 {
5275 	int copyflag;
5276 	int elt;
5277 	struct sk_buff *skb1, **skb_p;
5278 
5279 	/* If skb is cloned or its head is paged, reallocate
5280 	 * head pulling out all the pages (pages are considered not writable
5281 	 * at the moment even if they are anonymous).
5282 	 */
5283 	if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
5284 	    !__pskb_pull_tail(skb, __skb_pagelen(skb)))
5285 		return -ENOMEM;
5286 
5287 	/* Easy case. Most of packets will go this way. */
5288 	if (!skb_has_frag_list(skb)) {
5289 		/* A little of trouble, not enough of space for trailer.
5290 		 * This should not happen, when stack is tuned to generate
5291 		 * good frames. OK, on miss we reallocate and reserve even more
5292 		 * space, 128 bytes is fair. */
5293 
5294 		if (skb_tailroom(skb) < tailbits &&
5295 		    pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
5296 			return -ENOMEM;
5297 
5298 		/* Voila! */
5299 		*trailer = skb;
5300 		return 1;
5301 	}
5302 
5303 	/* Misery. We are in troubles, going to mincer fragments... */
5304 
5305 	elt = 1;
5306 	skb_p = &skb_shinfo(skb)->frag_list;
5307 	copyflag = 0;
5308 
5309 	while ((skb1 = *skb_p) != NULL) {
5310 		int ntail = 0;
5311 
5312 		/* The fragment is partially pulled by someone,
5313 		 * this can happen on input. Copy it and everything
5314 		 * after it. */
5315 
5316 		if (skb_shared(skb1))
5317 			copyflag = 1;
5318 
5319 		/* If the skb is the last, worry about trailer. */
5320 
5321 		if (skb1->next == NULL && tailbits) {
5322 			if (skb_shinfo(skb1)->nr_frags ||
5323 			    skb_has_frag_list(skb1) ||
5324 			    skb_tailroom(skb1) < tailbits)
5325 				ntail = tailbits + 128;
5326 		}
5327 
5328 		if (copyflag ||
5329 		    skb_cloned(skb1) ||
5330 		    ntail ||
5331 		    skb_shinfo(skb1)->nr_frags ||
5332 		    skb_has_frag_list(skb1)) {
5333 			struct sk_buff *skb2;
5334 
5335 			/* Fuck, we are miserable poor guys... */
5336 			if (ntail == 0)
5337 				skb2 = skb_copy(skb1, GFP_ATOMIC);
5338 			else
5339 				skb2 = skb_copy_expand(skb1,
5340 						       skb_headroom(skb1),
5341 						       ntail,
5342 						       GFP_ATOMIC);
5343 			if (unlikely(skb2 == NULL))
5344 				return -ENOMEM;
5345 
5346 			if (skb1->sk)
5347 				skb_set_owner_w(skb2, skb1->sk);
5348 
5349 			/* Looking around. Are we still alive?
5350 			 * OK, link new skb, drop old one */
5351 
5352 			skb2->next = skb1->next;
5353 			*skb_p = skb2;
5354 			kfree_skb(skb1);
5355 			skb1 = skb2;
5356 		}
5357 		elt++;
5358 		*trailer = skb1;
5359 		skb_p = &skb1->next;
5360 	}
5361 
5362 	return elt;
5363 }
5364 EXPORT_SYMBOL_GPL(skb_cow_data);
5365 
sock_rmem_free(struct sk_buff * skb)5366 static void sock_rmem_free(struct sk_buff *skb)
5367 {
5368 	struct sock *sk = skb->sk;
5369 
5370 	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
5371 }
5372 
skb_set_err_queue(struct sk_buff * skb)5373 static void skb_set_err_queue(struct sk_buff *skb)
5374 {
5375 	/* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
5376 	 * So, it is safe to (mis)use it to mark skbs on the error queue.
5377 	 */
5378 	skb->pkt_type = PACKET_OUTGOING;
5379 	BUILD_BUG_ON(PACKET_OUTGOING == 0);
5380 }
5381 
5382 /*
5383  * Note: We dont mem charge error packets (no sk_forward_alloc changes)
5384  */
sock_queue_err_skb(struct sock * sk,struct sk_buff * skb)5385 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
5386 {
5387 	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
5388 	    (unsigned int)READ_ONCE(sk->sk_rcvbuf))
5389 		return -ENOMEM;
5390 
5391 	skb_orphan(skb);
5392 	skb->sk = sk;
5393 	skb->destructor = sock_rmem_free;
5394 	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
5395 	skb_set_err_queue(skb);
5396 
5397 	/* before exiting rcu section, make sure dst is refcounted */
5398 	skb_dst_force(skb);
5399 
5400 	skb_queue_tail(&sk->sk_error_queue, skb);
5401 	if (!sock_flag(sk, SOCK_DEAD))
5402 		sk_error_report(sk);
5403 	return 0;
5404 }
5405 EXPORT_SYMBOL(sock_queue_err_skb);
5406 
is_icmp_err_skb(const struct sk_buff * skb)5407 static bool is_icmp_err_skb(const struct sk_buff *skb)
5408 {
5409 	return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
5410 		       SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6);
5411 }
5412 
sock_dequeue_err_skb(struct sock * sk)5413 struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
5414 {
5415 	struct sk_buff_head *q = &sk->sk_error_queue;
5416 	struct sk_buff *skb, *skb_next = NULL;
5417 	bool icmp_next = false;
5418 	unsigned long flags;
5419 
5420 	if (skb_queue_empty_lockless(q))
5421 		return NULL;
5422 
5423 	spin_lock_irqsave(&q->lock, flags);
5424 	skb = __skb_dequeue(q);
5425 	if (skb && (skb_next = skb_peek(q))) {
5426 		icmp_next = is_icmp_err_skb(skb_next);
5427 		if (icmp_next)
5428 			sk->sk_err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
5429 	}
5430 	spin_unlock_irqrestore(&q->lock, flags);
5431 
5432 	if (is_icmp_err_skb(skb) && !icmp_next)
5433 		sk->sk_err = 0;
5434 
5435 	if (skb_next)
5436 		sk_error_report(sk);
5437 
5438 	return skb;
5439 }
5440 EXPORT_SYMBOL(sock_dequeue_err_skb);
5441 
5442 /**
5443  * skb_clone_sk - create clone of skb, and take reference to socket
5444  * @skb: the skb to clone
5445  *
5446  * This function creates a clone of a buffer that holds a reference on
5447  * sk_refcnt.  Buffers created via this function are meant to be
5448  * returned using sock_queue_err_skb, or free via kfree_skb.
5449  *
5450  * When passing buffers allocated with this function to sock_queue_err_skb
5451  * it is necessary to wrap the call with sock_hold/sock_put in order to
5452  * prevent the socket from being released prior to being enqueued on
5453  * the sk_error_queue.
5454  */
skb_clone_sk(struct sk_buff * skb)5455 struct sk_buff *skb_clone_sk(struct sk_buff *skb)
5456 {
5457 	struct sock *sk = skb->sk;
5458 	struct sk_buff *clone;
5459 
5460 	if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
5461 		return NULL;
5462 
5463 	clone = skb_clone(skb, GFP_ATOMIC);
5464 	if (!clone) {
5465 		sock_put(sk);
5466 		return NULL;
5467 	}
5468 
5469 	clone->sk = sk;
5470 	clone->destructor = sock_efree;
5471 
5472 	return clone;
5473 }
5474 EXPORT_SYMBOL(skb_clone_sk);
5475 
__skb_complete_tx_timestamp(struct sk_buff * skb,struct sock * sk,int tstype,bool opt_stats)5476 static void __skb_complete_tx_timestamp(struct sk_buff *skb,
5477 					struct sock *sk,
5478 					int tstype,
5479 					bool opt_stats)
5480 {
5481 	struct sock_exterr_skb *serr;
5482 	int err;
5483 
5484 	BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
5485 
5486 	serr = SKB_EXT_ERR(skb);
5487 	memset(serr, 0, sizeof(*serr));
5488 	serr->ee.ee_errno = ENOMSG;
5489 	serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
5490 	serr->ee.ee_info = tstype;
5491 	serr->opt_stats = opt_stats;
5492 	serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
5493 	if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
5494 		serr->ee.ee_data = skb_shinfo(skb)->tskey;
5495 		if (sk_is_tcp(sk))
5496 			serr->ee.ee_data -= atomic_read(&sk->sk_tskey);
5497 	}
5498 
5499 	err = sock_queue_err_skb(sk, skb);
5500 
5501 	if (err)
5502 		kfree_skb(skb);
5503 }
5504 
skb_may_tx_timestamp(struct sock * sk,bool tsonly)5505 static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
5506 {
5507 	bool ret;
5508 
5509 	if (likely(READ_ONCE(sysctl_tstamp_allow_data) || tsonly))
5510 		return true;
5511 
5512 	read_lock_bh(&sk->sk_callback_lock);
5513 	ret = sk->sk_socket && sk->sk_socket->file &&
5514 	      file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
5515 	read_unlock_bh(&sk->sk_callback_lock);
5516 	return ret;
5517 }
5518 
skb_complete_tx_timestamp(struct sk_buff * skb,struct skb_shared_hwtstamps * hwtstamps)5519 void skb_complete_tx_timestamp(struct sk_buff *skb,
5520 			       struct skb_shared_hwtstamps *hwtstamps)
5521 {
5522 	struct sock *sk = skb->sk;
5523 
5524 	if (!skb_may_tx_timestamp(sk, false))
5525 		goto err;
5526 
5527 	/* Take a reference to prevent skb_orphan() from freeing the socket,
5528 	 * but only if the socket refcount is not zero.
5529 	 */
5530 	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
5531 		*skb_hwtstamps(skb) = *hwtstamps;
5532 		__skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
5533 		sock_put(sk);
5534 		return;
5535 	}
5536 
5537 err:
5538 	kfree_skb(skb);
5539 }
5540 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
5541 
__skb_tstamp_tx(struct sk_buff * orig_skb,const struct sk_buff * ack_skb,struct skb_shared_hwtstamps * hwtstamps,struct sock * sk,int tstype)5542 void __skb_tstamp_tx(struct sk_buff *orig_skb,
5543 		     const struct sk_buff *ack_skb,
5544 		     struct skb_shared_hwtstamps *hwtstamps,
5545 		     struct sock *sk, int tstype)
5546 {
5547 	struct sk_buff *skb;
5548 	bool tsonly, opt_stats = false;
5549 	u32 tsflags;
5550 
5551 	if (!sk)
5552 		return;
5553 
5554 	tsflags = READ_ONCE(sk->sk_tsflags);
5555 	if (!hwtstamps && !(tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
5556 	    skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
5557 		return;
5558 
5559 	tsonly = tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
5560 	if (!skb_may_tx_timestamp(sk, tsonly))
5561 		return;
5562 
5563 	if (tsonly) {
5564 #ifdef CONFIG_INET
5565 		if ((tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
5566 		    sk_is_tcp(sk)) {
5567 			skb = tcp_get_timestamping_opt_stats(sk, orig_skb,
5568 							     ack_skb);
5569 			opt_stats = true;
5570 		} else
5571 #endif
5572 			skb = alloc_skb(0, GFP_ATOMIC);
5573 	} else {
5574 		skb = skb_clone(orig_skb, GFP_ATOMIC);
5575 
5576 		if (skb_orphan_frags_rx(skb, GFP_ATOMIC)) {
5577 			kfree_skb(skb);
5578 			return;
5579 		}
5580 	}
5581 	if (!skb)
5582 		return;
5583 
5584 	if (tsonly) {
5585 		skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &
5586 					     SKBTX_ANY_TSTAMP;
5587 		skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
5588 	}
5589 
5590 	if (hwtstamps)
5591 		*skb_hwtstamps(skb) = *hwtstamps;
5592 	else
5593 		__net_timestamp(skb);
5594 
5595 	__skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
5596 }
5597 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
5598 
skb_tstamp_tx(struct sk_buff * orig_skb,struct skb_shared_hwtstamps * hwtstamps)5599 void skb_tstamp_tx(struct sk_buff *orig_skb,
5600 		   struct skb_shared_hwtstamps *hwtstamps)
5601 {
5602 	return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
5603 			       SCM_TSTAMP_SND);
5604 }
5605 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
5606 
5607 #ifdef CONFIG_WIRELESS
skb_complete_wifi_ack(struct sk_buff * skb,bool acked)5608 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
5609 {
5610 	struct sock *sk = skb->sk;
5611 	struct sock_exterr_skb *serr;
5612 	int err = 1;
5613 
5614 	skb->wifi_acked_valid = 1;
5615 	skb->wifi_acked = acked;
5616 
5617 	serr = SKB_EXT_ERR(skb);
5618 	memset(serr, 0, sizeof(*serr));
5619 	serr->ee.ee_errno = ENOMSG;
5620 	serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
5621 
5622 	/* Take a reference to prevent skb_orphan() from freeing the socket,
5623 	 * but only if the socket refcount is not zero.
5624 	 */
5625 	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
5626 		err = sock_queue_err_skb(sk, skb);
5627 		sock_put(sk);
5628 	}
5629 	if (err)
5630 		kfree_skb(skb);
5631 }
5632 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
5633 #endif /* CONFIG_WIRELESS */
5634 
5635 /**
5636  * skb_partial_csum_set - set up and verify partial csum values for packet
5637  * @skb: the skb to set
5638  * @start: the number of bytes after skb->data to start checksumming.
5639  * @off: the offset from start to place the checksum.
5640  *
5641  * For untrusted partially-checksummed packets, we need to make sure the values
5642  * for skb->csum_start and skb->csum_offset are valid so we don't oops.
5643  *
5644  * This function checks and sets those values and skb->ip_summed: if this
5645  * returns false you should drop the packet.
5646  */
skb_partial_csum_set(struct sk_buff * skb,u16 start,u16 off)5647 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
5648 {
5649 	u32 csum_end = (u32)start + (u32)off + sizeof(__sum16);
5650 	u32 csum_start = skb_headroom(skb) + (u32)start;
5651 
5652 	if (unlikely(csum_start >= U16_MAX || csum_end > skb_headlen(skb))) {
5653 		net_warn_ratelimited("bad partial csum: csum=%u/%u headroom=%u headlen=%u\n",
5654 				     start, off, skb_headroom(skb), skb_headlen(skb));
5655 		return false;
5656 	}
5657 	skb->ip_summed = CHECKSUM_PARTIAL;
5658 	skb->csum_start = csum_start;
5659 	skb->csum_offset = off;
5660 	skb->transport_header = csum_start;
5661 	return true;
5662 }
5663 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
5664 
skb_maybe_pull_tail(struct sk_buff * skb,unsigned int len,unsigned int max)5665 static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
5666 			       unsigned int max)
5667 {
5668 	if (skb_headlen(skb) >= len)
5669 		return 0;
5670 
5671 	/* If we need to pullup then pullup to the max, so we
5672 	 * won't need to do it again.
5673 	 */
5674 	if (max > skb->len)
5675 		max = skb->len;
5676 
5677 	if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
5678 		return -ENOMEM;
5679 
5680 	if (skb_headlen(skb) < len)
5681 		return -EPROTO;
5682 
5683 	return 0;
5684 }
5685 
5686 #define MAX_TCP_HDR_LEN (15 * 4)
5687 
skb_checksum_setup_ip(struct sk_buff * skb,typeof (IPPROTO_IP)proto,unsigned int off)5688 static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
5689 				      typeof(IPPROTO_IP) proto,
5690 				      unsigned int off)
5691 {
5692 	int err;
5693 
5694 	switch (proto) {
5695 	case IPPROTO_TCP:
5696 		err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
5697 					  off + MAX_TCP_HDR_LEN);
5698 		if (!err && !skb_partial_csum_set(skb, off,
5699 						  offsetof(struct tcphdr,
5700 							   check)))
5701 			err = -EPROTO;
5702 		return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
5703 
5704 	case IPPROTO_UDP:
5705 		err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
5706 					  off + sizeof(struct udphdr));
5707 		if (!err && !skb_partial_csum_set(skb, off,
5708 						  offsetof(struct udphdr,
5709 							   check)))
5710 			err = -EPROTO;
5711 		return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
5712 	}
5713 
5714 	return ERR_PTR(-EPROTO);
5715 }
5716 
5717 /* This value should be large enough to cover a tagged ethernet header plus
5718  * maximally sized IP and TCP or UDP headers.
5719  */
5720 #define MAX_IP_HDR_LEN 128
5721 
skb_checksum_setup_ipv4(struct sk_buff * skb,bool recalculate)5722 static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
5723 {
5724 	unsigned int off;
5725 	bool fragment;
5726 	__sum16 *csum;
5727 	int err;
5728 
5729 	fragment = false;
5730 
5731 	err = skb_maybe_pull_tail(skb,
5732 				  sizeof(struct iphdr),
5733 				  MAX_IP_HDR_LEN);
5734 	if (err < 0)
5735 		goto out;
5736 
5737 	if (ip_is_fragment(ip_hdr(skb)))
5738 		fragment = true;
5739 
5740 	off = ip_hdrlen(skb);
5741 
5742 	err = -EPROTO;
5743 
5744 	if (fragment)
5745 		goto out;
5746 
5747 	csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
5748 	if (IS_ERR(csum))
5749 		return PTR_ERR(csum);
5750 
5751 	if (recalculate)
5752 		*csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
5753 					   ip_hdr(skb)->daddr,
5754 					   skb->len - off,
5755 					   ip_hdr(skb)->protocol, 0);
5756 	err = 0;
5757 
5758 out:
5759 	return err;
5760 }
5761 
5762 /* This value should be large enough to cover a tagged ethernet header plus
5763  * an IPv6 header, all options, and a maximal TCP or UDP header.
5764  */
5765 #define MAX_IPV6_HDR_LEN 256
5766 
5767 #define OPT_HDR(type, skb, off) \
5768 	(type *)(skb_network_header(skb) + (off))
5769 
skb_checksum_setup_ipv6(struct sk_buff * skb,bool recalculate)5770 static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
5771 {
5772 	int err;
5773 	u8 nexthdr;
5774 	unsigned int off;
5775 	unsigned int len;
5776 	bool fragment;
5777 	bool done;
5778 	__sum16 *csum;
5779 
5780 	fragment = false;
5781 	done = false;
5782 
5783 	off = sizeof(struct ipv6hdr);
5784 
5785 	err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
5786 	if (err < 0)
5787 		goto out;
5788 
5789 	nexthdr = ipv6_hdr(skb)->nexthdr;
5790 
5791 	len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
5792 	while (off <= len && !done) {
5793 		switch (nexthdr) {
5794 		case IPPROTO_DSTOPTS:
5795 		case IPPROTO_HOPOPTS:
5796 		case IPPROTO_ROUTING: {
5797 			struct ipv6_opt_hdr *hp;
5798 
5799 			err = skb_maybe_pull_tail(skb,
5800 						  off +
5801 						  sizeof(struct ipv6_opt_hdr),
5802 						  MAX_IPV6_HDR_LEN);
5803 			if (err < 0)
5804 				goto out;
5805 
5806 			hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
5807 			nexthdr = hp->nexthdr;
5808 			off += ipv6_optlen(hp);
5809 			break;
5810 		}
5811 		case IPPROTO_AH: {
5812 			struct ip_auth_hdr *hp;
5813 
5814 			err = skb_maybe_pull_tail(skb,
5815 						  off +
5816 						  sizeof(struct ip_auth_hdr),
5817 						  MAX_IPV6_HDR_LEN);
5818 			if (err < 0)
5819 				goto out;
5820 
5821 			hp = OPT_HDR(struct ip_auth_hdr, skb, off);
5822 			nexthdr = hp->nexthdr;
5823 			off += ipv6_authlen(hp);
5824 			break;
5825 		}
5826 		case IPPROTO_FRAGMENT: {
5827 			struct frag_hdr *hp;
5828 
5829 			err = skb_maybe_pull_tail(skb,
5830 						  off +
5831 						  sizeof(struct frag_hdr),
5832 						  MAX_IPV6_HDR_LEN);
5833 			if (err < 0)
5834 				goto out;
5835 
5836 			hp = OPT_HDR(struct frag_hdr, skb, off);
5837 
5838 			if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
5839 				fragment = true;
5840 
5841 			nexthdr = hp->nexthdr;
5842 			off += sizeof(struct frag_hdr);
5843 			break;
5844 		}
5845 		default:
5846 			done = true;
5847 			break;
5848 		}
5849 	}
5850 
5851 	err = -EPROTO;
5852 
5853 	if (!done || fragment)
5854 		goto out;
5855 
5856 	csum = skb_checksum_setup_ip(skb, nexthdr, off);
5857 	if (IS_ERR(csum))
5858 		return PTR_ERR(csum);
5859 
5860 	if (recalculate)
5861 		*csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
5862 					 &ipv6_hdr(skb)->daddr,
5863 					 skb->len - off, nexthdr, 0);
5864 	err = 0;
5865 
5866 out:
5867 	return err;
5868 }
5869 
5870 /**
5871  * skb_checksum_setup - set up partial checksum offset
5872  * @skb: the skb to set up
5873  * @recalculate: if true the pseudo-header checksum will be recalculated
5874  */
skb_checksum_setup(struct sk_buff * skb,bool recalculate)5875 int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
5876 {
5877 	int err;
5878 
5879 	switch (skb->protocol) {
5880 	case htons(ETH_P_IP):
5881 		err = skb_checksum_setup_ipv4(skb, recalculate);
5882 		break;
5883 
5884 	case htons(ETH_P_IPV6):
5885 		err = skb_checksum_setup_ipv6(skb, recalculate);
5886 		break;
5887 
5888 	default:
5889 		err = -EPROTO;
5890 		break;
5891 	}
5892 
5893 	return err;
5894 }
5895 EXPORT_SYMBOL(skb_checksum_setup);
5896 
5897 /**
5898  * skb_checksum_maybe_trim - maybe trims the given skb
5899  * @skb: the skb to check
5900  * @transport_len: the data length beyond the network header
5901  *
5902  * Checks whether the given skb has data beyond the given transport length.
5903  * If so, returns a cloned skb trimmed to this transport length.
5904  * Otherwise returns the provided skb. Returns NULL in error cases
5905  * (e.g. transport_len exceeds skb length or out-of-memory).
5906  *
5907  * Caller needs to set the skb transport header and free any returned skb if it
5908  * differs from the provided skb.
5909  */
skb_checksum_maybe_trim(struct sk_buff * skb,unsigned int transport_len)5910 static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
5911 					       unsigned int transport_len)
5912 {
5913 	struct sk_buff *skb_chk;
5914 	unsigned int len = skb_transport_offset(skb) + transport_len;
5915 	int ret;
5916 
5917 	if (skb->len < len)
5918 		return NULL;
5919 	else if (skb->len == len)
5920 		return skb;
5921 
5922 	skb_chk = skb_clone(skb, GFP_ATOMIC);
5923 	if (!skb_chk)
5924 		return NULL;
5925 
5926 	ret = pskb_trim_rcsum(skb_chk, len);
5927 	if (ret) {
5928 		kfree_skb(skb_chk);
5929 		return NULL;
5930 	}
5931 
5932 	return skb_chk;
5933 }
5934 
5935 /**
5936  * skb_checksum_trimmed - validate checksum of an skb
5937  * @skb: the skb to check
5938  * @transport_len: the data length beyond the network header
5939  * @skb_chkf: checksum function to use
5940  *
5941  * Applies the given checksum function skb_chkf to the provided skb.
5942  * Returns a checked and maybe trimmed skb. Returns NULL on error.
5943  *
5944  * If the skb has data beyond the given transport length, then a
5945  * trimmed & cloned skb is checked and returned.
5946  *
5947  * Caller needs to set the skb transport header and free any returned skb if it
5948  * differs from the provided skb.
5949  */
skb_checksum_trimmed(struct sk_buff * skb,unsigned int transport_len,__sum16 (* skb_chkf)(struct sk_buff * skb))5950 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
5951 				     unsigned int transport_len,
5952 				     __sum16(*skb_chkf)(struct sk_buff *skb))
5953 {
5954 	struct sk_buff *skb_chk;
5955 	unsigned int offset = skb_transport_offset(skb);
5956 	__sum16 ret;
5957 
5958 	skb_chk = skb_checksum_maybe_trim(skb, transport_len);
5959 	if (!skb_chk)
5960 		goto err;
5961 
5962 	if (!pskb_may_pull(skb_chk, offset))
5963 		goto err;
5964 
5965 	skb_pull_rcsum(skb_chk, offset);
5966 	ret = skb_chkf(skb_chk);
5967 	skb_push_rcsum(skb_chk, offset);
5968 
5969 	if (ret)
5970 		goto err;
5971 
5972 	return skb_chk;
5973 
5974 err:
5975 	if (skb_chk && skb_chk != skb)
5976 		kfree_skb(skb_chk);
5977 
5978 	return NULL;
5979 
5980 }
5981 EXPORT_SYMBOL(skb_checksum_trimmed);
5982 
__skb_warn_lro_forwarding(const struct sk_buff * skb)5983 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
5984 {
5985 	net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
5986 			     skb->dev->name);
5987 }
5988 EXPORT_SYMBOL(__skb_warn_lro_forwarding);
5989 
kfree_skb_partial(struct sk_buff * skb,bool head_stolen)5990 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
5991 {
5992 	if (head_stolen) {
5993 		skb_release_head_state(skb);
5994 		kmem_cache_free(net_hotdata.skbuff_cache, skb);
5995 	} else {
5996 		__kfree_skb(skb);
5997 	}
5998 }
5999 EXPORT_SYMBOL(kfree_skb_partial);
6000 
6001 /**
6002  * skb_try_coalesce - try to merge skb to prior one
6003  * @to: prior buffer
6004  * @from: buffer to add
6005  * @fragstolen: pointer to boolean
6006  * @delta_truesize: how much more was allocated than was requested
6007  */
skb_try_coalesce(struct sk_buff * to,struct sk_buff * from,bool * fragstolen,int * delta_truesize)6008 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
6009 		      bool *fragstolen, int *delta_truesize)
6010 {
6011 	struct skb_shared_info *to_shinfo, *from_shinfo;
6012 	int i, delta, len = from->len;
6013 
6014 	*fragstolen = false;
6015 
6016 	if (skb_cloned(to))
6017 		return false;
6018 
6019 	/* In general, avoid mixing page_pool and non-page_pool allocated
6020 	 * pages within the same SKB. In theory we could take full
6021 	 * references if @from is cloned and !@to->pp_recycle but its
6022 	 * tricky (due to potential race with the clone disappearing) and
6023 	 * rare, so not worth dealing with.
6024 	 */
6025 	if (to->pp_recycle != from->pp_recycle)
6026 		return false;
6027 
6028 	if (skb_frags_readable(from) != skb_frags_readable(to))
6029 		return false;
6030 
6031 	if (len <= skb_tailroom(to) && skb_frags_readable(from)) {
6032 		if (len)
6033 			BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
6034 		*delta_truesize = 0;
6035 		return true;
6036 	}
6037 
6038 	to_shinfo = skb_shinfo(to);
6039 	from_shinfo = skb_shinfo(from);
6040 	if (to_shinfo->frag_list || from_shinfo->frag_list)
6041 		return false;
6042 	if (skb_zcopy(to) || skb_zcopy(from))
6043 		return false;
6044 
6045 	if (skb_headlen(from) != 0) {
6046 		struct page *page;
6047 		unsigned int offset;
6048 
6049 		if (to_shinfo->nr_frags +
6050 		    from_shinfo->nr_frags >= MAX_SKB_FRAGS)
6051 			return false;
6052 
6053 		if (skb_head_is_locked(from))
6054 			return false;
6055 
6056 		delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
6057 
6058 		page = virt_to_head_page(from->head);
6059 		offset = from->data - (unsigned char *)page_address(page);
6060 
6061 		skb_fill_page_desc(to, to_shinfo->nr_frags,
6062 				   page, offset, skb_headlen(from));
6063 		*fragstolen = true;
6064 	} else {
6065 		if (to_shinfo->nr_frags +
6066 		    from_shinfo->nr_frags > MAX_SKB_FRAGS)
6067 			return false;
6068 
6069 		delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
6070 	}
6071 
6072 	WARN_ON_ONCE(delta < len);
6073 
6074 	memcpy(to_shinfo->frags + to_shinfo->nr_frags,
6075 	       from_shinfo->frags,
6076 	       from_shinfo->nr_frags * sizeof(skb_frag_t));
6077 	to_shinfo->nr_frags += from_shinfo->nr_frags;
6078 
6079 	if (!skb_cloned(from))
6080 		from_shinfo->nr_frags = 0;
6081 
6082 	/* if the skb is not cloned this does nothing
6083 	 * since we set nr_frags to 0.
6084 	 */
6085 	if (skb_pp_frag_ref(from)) {
6086 		for (i = 0; i < from_shinfo->nr_frags; i++)
6087 			__skb_frag_ref(&from_shinfo->frags[i]);
6088 	}
6089 
6090 	to->truesize += delta;
6091 	to->len += len;
6092 	to->data_len += len;
6093 
6094 	*delta_truesize = delta;
6095 	return true;
6096 }
6097 EXPORT_SYMBOL(skb_try_coalesce);
6098 
6099 /**
6100  * skb_scrub_packet - scrub an skb
6101  *
6102  * @skb: buffer to clean
6103  * @xnet: packet is crossing netns
6104  *
6105  * skb_scrub_packet can be used after encapsulating or decapsulating a packet
6106  * into/from a tunnel. Some information have to be cleared during these
6107  * operations.
6108  * skb_scrub_packet can also be used to clean a skb before injecting it in
6109  * another namespace (@xnet == true). We have to clear all information in the
6110  * skb that could impact namespace isolation.
6111  */
skb_scrub_packet(struct sk_buff * skb,bool xnet)6112 void skb_scrub_packet(struct sk_buff *skb, bool xnet)
6113 {
6114 	skb->pkt_type = PACKET_HOST;
6115 	skb->skb_iif = 0;
6116 	skb->ignore_df = 0;
6117 	skb_dst_drop(skb);
6118 	skb_ext_reset(skb);
6119 	nf_reset_ct(skb);
6120 	nf_reset_trace(skb);
6121 
6122 #ifdef CONFIG_NET_SWITCHDEV
6123 	skb->offload_fwd_mark = 0;
6124 	skb->offload_l3_fwd_mark = 0;
6125 #endif
6126 
6127 	if (!xnet)
6128 		return;
6129 
6130 	ipvs_reset(skb);
6131 	skb->mark = 0;
6132 	skb_clear_tstamp(skb);
6133 }
6134 EXPORT_SYMBOL_GPL(skb_scrub_packet);
6135 
skb_reorder_vlan_header(struct sk_buff * skb)6136 static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
6137 {
6138 	int mac_len, meta_len;
6139 	void *meta;
6140 
6141 	if (skb_cow(skb, skb_headroom(skb)) < 0) {
6142 		kfree_skb(skb);
6143 		return NULL;
6144 	}
6145 
6146 	mac_len = skb->data - skb_mac_header(skb);
6147 	if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) {
6148 		memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
6149 			mac_len - VLAN_HLEN - ETH_TLEN);
6150 	}
6151 
6152 	meta_len = skb_metadata_len(skb);
6153 	if (meta_len) {
6154 		meta = skb_metadata_end(skb) - meta_len;
6155 		memmove(meta + VLAN_HLEN, meta, meta_len);
6156 	}
6157 
6158 	skb->mac_header += VLAN_HLEN;
6159 	return skb;
6160 }
6161 
skb_vlan_untag(struct sk_buff * skb)6162 struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
6163 {
6164 	struct vlan_hdr *vhdr;
6165 	u16 vlan_tci;
6166 
6167 	if (unlikely(skb_vlan_tag_present(skb))) {
6168 		/* vlan_tci is already set-up so leave this for another time */
6169 		return skb;
6170 	}
6171 
6172 	skb = skb_share_check(skb, GFP_ATOMIC);
6173 	if (unlikely(!skb))
6174 		goto err_free;
6175 	/* We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). */
6176 	if (unlikely(!pskb_may_pull(skb, VLAN_HLEN + sizeof(unsigned short))))
6177 		goto err_free;
6178 
6179 	vhdr = (struct vlan_hdr *)skb->data;
6180 	vlan_tci = ntohs(vhdr->h_vlan_TCI);
6181 	__vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
6182 
6183 	skb_pull_rcsum(skb, VLAN_HLEN);
6184 	vlan_set_encap_proto(skb, vhdr);
6185 
6186 	skb = skb_reorder_vlan_header(skb);
6187 	if (unlikely(!skb))
6188 		goto err_free;
6189 
6190 	skb_reset_network_header(skb);
6191 	if (!skb_transport_header_was_set(skb))
6192 		skb_reset_transport_header(skb);
6193 	skb_reset_mac_len(skb);
6194 
6195 	return skb;
6196 
6197 err_free:
6198 	kfree_skb(skb);
6199 	return NULL;
6200 }
6201 EXPORT_SYMBOL(skb_vlan_untag);
6202 
skb_ensure_writable(struct sk_buff * skb,unsigned int write_len)6203 int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len)
6204 {
6205 	if (!pskb_may_pull(skb, write_len))
6206 		return -ENOMEM;
6207 
6208 	if (!skb_frags_readable(skb))
6209 		return -EFAULT;
6210 
6211 	if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
6212 		return 0;
6213 
6214 	return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
6215 }
6216 EXPORT_SYMBOL(skb_ensure_writable);
6217 
skb_ensure_writable_head_tail(struct sk_buff * skb,struct net_device * dev)6218 int skb_ensure_writable_head_tail(struct sk_buff *skb, struct net_device *dev)
6219 {
6220 	int needed_headroom = dev->needed_headroom;
6221 	int needed_tailroom = dev->needed_tailroom;
6222 
6223 	/* For tail taggers, we need to pad short frames ourselves, to ensure
6224 	 * that the tail tag does not fail at its role of being at the end of
6225 	 * the packet, once the conduit interface pads the frame. Account for
6226 	 * that pad length here, and pad later.
6227 	 */
6228 	if (unlikely(needed_tailroom && skb->len < ETH_ZLEN))
6229 		needed_tailroom += ETH_ZLEN - skb->len;
6230 	/* skb_headroom() returns unsigned int... */
6231 	needed_headroom = max_t(int, needed_headroom - skb_headroom(skb), 0);
6232 	needed_tailroom = max_t(int, needed_tailroom - skb_tailroom(skb), 0);
6233 
6234 	if (likely(!needed_headroom && !needed_tailroom && !skb_cloned(skb)))
6235 		/* No reallocation needed, yay! */
6236 		return 0;
6237 
6238 	return pskb_expand_head(skb, needed_headroom, needed_tailroom,
6239 				GFP_ATOMIC);
6240 }
6241 EXPORT_SYMBOL(skb_ensure_writable_head_tail);
6242 
6243 /* remove VLAN header from packet and update csum accordingly.
6244  * expects a non skb_vlan_tag_present skb with a vlan tag payload
6245  */
__skb_vlan_pop(struct sk_buff * skb,u16 * vlan_tci)6246 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
6247 {
6248 	int offset = skb->data - skb_mac_header(skb);
6249 	int err;
6250 
6251 	if (WARN_ONCE(offset,
6252 		      "__skb_vlan_pop got skb with skb->data not at mac header (offset %d)\n",
6253 		      offset)) {
6254 		return -EINVAL;
6255 	}
6256 
6257 	err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
6258 	if (unlikely(err))
6259 		return err;
6260 
6261 	skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
6262 
6263 	vlan_remove_tag(skb, vlan_tci);
6264 
6265 	skb->mac_header += VLAN_HLEN;
6266 
6267 	if (skb_network_offset(skb) < ETH_HLEN)
6268 		skb_set_network_header(skb, ETH_HLEN);
6269 
6270 	skb_reset_mac_len(skb);
6271 
6272 	return err;
6273 }
6274 EXPORT_SYMBOL(__skb_vlan_pop);
6275 
6276 /* Pop a vlan tag either from hwaccel or from payload.
6277  * Expects skb->data at mac header.
6278  */
skb_vlan_pop(struct sk_buff * skb)6279 int skb_vlan_pop(struct sk_buff *skb)
6280 {
6281 	u16 vlan_tci;
6282 	__be16 vlan_proto;
6283 	int err;
6284 
6285 	if (likely(skb_vlan_tag_present(skb))) {
6286 		__vlan_hwaccel_clear_tag(skb);
6287 	} else {
6288 		if (unlikely(!eth_type_vlan(skb->protocol)))
6289 			return 0;
6290 
6291 		err = __skb_vlan_pop(skb, &vlan_tci);
6292 		if (err)
6293 			return err;
6294 	}
6295 	/* move next vlan tag to hw accel tag */
6296 	if (likely(!eth_type_vlan(skb->protocol)))
6297 		return 0;
6298 
6299 	vlan_proto = skb->protocol;
6300 	err = __skb_vlan_pop(skb, &vlan_tci);
6301 	if (unlikely(err))
6302 		return err;
6303 
6304 	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
6305 	return 0;
6306 }
6307 EXPORT_SYMBOL(skb_vlan_pop);
6308 
6309 /* Push a vlan tag either into hwaccel or into payload (if hwaccel tag present).
6310  * Expects skb->data at mac header.
6311  */
skb_vlan_push(struct sk_buff * skb,__be16 vlan_proto,u16 vlan_tci)6312 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
6313 {
6314 	if (skb_vlan_tag_present(skb)) {
6315 		int offset = skb->data - skb_mac_header(skb);
6316 		int err;
6317 
6318 		if (WARN_ONCE(offset,
6319 			      "skb_vlan_push got skb with skb->data not at mac header (offset %d)\n",
6320 			      offset)) {
6321 			return -EINVAL;
6322 		}
6323 
6324 		err = __vlan_insert_tag(skb, skb->vlan_proto,
6325 					skb_vlan_tag_get(skb));
6326 		if (err)
6327 			return err;
6328 
6329 		skb->protocol = skb->vlan_proto;
6330 		skb->network_header -= VLAN_HLEN;
6331 
6332 		skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
6333 	}
6334 	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
6335 	return 0;
6336 }
6337 EXPORT_SYMBOL(skb_vlan_push);
6338 
6339 /**
6340  * skb_eth_pop() - Drop the Ethernet header at the head of a packet
6341  *
6342  * @skb: Socket buffer to modify
6343  *
6344  * Drop the Ethernet header of @skb.
6345  *
6346  * Expects that skb->data points to the mac header and that no VLAN tags are
6347  * present.
6348  *
6349  * Returns 0 on success, -errno otherwise.
6350  */
skb_eth_pop(struct sk_buff * skb)6351 int skb_eth_pop(struct sk_buff *skb)
6352 {
6353 	if (!pskb_may_pull(skb, ETH_HLEN) || skb_vlan_tagged(skb) ||
6354 	    skb_network_offset(skb) < ETH_HLEN)
6355 		return -EPROTO;
6356 
6357 	skb_pull_rcsum(skb, ETH_HLEN);
6358 	skb_reset_mac_header(skb);
6359 	skb_reset_mac_len(skb);
6360 
6361 	return 0;
6362 }
6363 EXPORT_SYMBOL(skb_eth_pop);
6364 
6365 /**
6366  * skb_eth_push() - Add a new Ethernet header at the head of a packet
6367  *
6368  * @skb: Socket buffer to modify
6369  * @dst: Destination MAC address of the new header
6370  * @src: Source MAC address of the new header
6371  *
6372  * Prepend @skb with a new Ethernet header.
6373  *
6374  * Expects that skb->data points to the mac header, which must be empty.
6375  *
6376  * Returns 0 on success, -errno otherwise.
6377  */
skb_eth_push(struct sk_buff * skb,const unsigned char * dst,const unsigned char * src)6378 int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
6379 		 const unsigned char *src)
6380 {
6381 	struct ethhdr *eth;
6382 	int err;
6383 
6384 	if (skb_network_offset(skb) || skb_vlan_tag_present(skb))
6385 		return -EPROTO;
6386 
6387 	err = skb_cow_head(skb, sizeof(*eth));
6388 	if (err < 0)
6389 		return err;
6390 
6391 	skb_push(skb, sizeof(*eth));
6392 	skb_reset_mac_header(skb);
6393 	skb_reset_mac_len(skb);
6394 
6395 	eth = eth_hdr(skb);
6396 	ether_addr_copy(eth->h_dest, dst);
6397 	ether_addr_copy(eth->h_source, src);
6398 	eth->h_proto = skb->protocol;
6399 
6400 	skb_postpush_rcsum(skb, eth, sizeof(*eth));
6401 
6402 	return 0;
6403 }
6404 EXPORT_SYMBOL(skb_eth_push);
6405 
6406 /* Update the ethertype of hdr and the skb csum value if required. */
skb_mod_eth_type(struct sk_buff * skb,struct ethhdr * hdr,__be16 ethertype)6407 static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
6408 			     __be16 ethertype)
6409 {
6410 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
6411 		__be16 diff[] = { ~hdr->h_proto, ethertype };
6412 
6413 		skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
6414 	}
6415 
6416 	hdr->h_proto = ethertype;
6417 }
6418 
6419 /**
6420  * skb_mpls_push() - push a new MPLS header after mac_len bytes from start of
6421  *                   the packet
6422  *
6423  * @skb: buffer
6424  * @mpls_lse: MPLS label stack entry to push
6425  * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
6426  * @mac_len: length of the MAC header
6427  * @ethernet: flag to indicate if the resulting packet after skb_mpls_push is
6428  *            ethernet
6429  *
6430  * Expects skb->data at mac header.
6431  *
6432  * Returns 0 on success, -errno otherwise.
6433  */
skb_mpls_push(struct sk_buff * skb,__be32 mpls_lse,__be16 mpls_proto,int mac_len,bool ethernet)6434 int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
6435 		  int mac_len, bool ethernet)
6436 {
6437 	struct mpls_shim_hdr *lse;
6438 	int err;
6439 
6440 	if (unlikely(!eth_p_mpls(mpls_proto)))
6441 		return -EINVAL;
6442 
6443 	/* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
6444 	if (skb->encapsulation)
6445 		return -EINVAL;
6446 
6447 	err = skb_cow_head(skb, MPLS_HLEN);
6448 	if (unlikely(err))
6449 		return err;
6450 
6451 	if (!skb->inner_protocol) {
6452 		skb_set_inner_network_header(skb, skb_network_offset(skb));
6453 		skb_set_inner_protocol(skb, skb->protocol);
6454 	}
6455 
6456 	skb_push(skb, MPLS_HLEN);
6457 	memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
6458 		mac_len);
6459 	skb_reset_mac_header(skb);
6460 	skb_set_network_header(skb, mac_len);
6461 	skb_reset_mac_len(skb);
6462 
6463 	lse = mpls_hdr(skb);
6464 	lse->label_stack_entry = mpls_lse;
6465 	skb_postpush_rcsum(skb, lse, MPLS_HLEN);
6466 
6467 	if (ethernet && mac_len >= ETH_HLEN)
6468 		skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
6469 	skb->protocol = mpls_proto;
6470 
6471 	return 0;
6472 }
6473 EXPORT_SYMBOL_GPL(skb_mpls_push);
6474 
6475 /**
6476  * skb_mpls_pop() - pop the outermost MPLS header
6477  *
6478  * @skb: buffer
6479  * @next_proto: ethertype of header after popped MPLS header
6480  * @mac_len: length of the MAC header
6481  * @ethernet: flag to indicate if the packet is ethernet
6482  *
6483  * Expects skb->data at mac header.
6484  *
6485  * Returns 0 on success, -errno otherwise.
6486  */
skb_mpls_pop(struct sk_buff * skb,__be16 next_proto,int mac_len,bool ethernet)6487 int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
6488 		 bool ethernet)
6489 {
6490 	int err;
6491 
6492 	if (unlikely(!eth_p_mpls(skb->protocol)))
6493 		return 0;
6494 
6495 	err = skb_ensure_writable(skb, mac_len + MPLS_HLEN);
6496 	if (unlikely(err))
6497 		return err;
6498 
6499 	skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);
6500 	memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
6501 		mac_len);
6502 
6503 	__skb_pull(skb, MPLS_HLEN);
6504 	skb_reset_mac_header(skb);
6505 	skb_set_network_header(skb, mac_len);
6506 
6507 	if (ethernet && mac_len >= ETH_HLEN) {
6508 		struct ethhdr *hdr;
6509 
6510 		/* use mpls_hdr() to get ethertype to account for VLANs. */
6511 		hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
6512 		skb_mod_eth_type(skb, hdr, next_proto);
6513 	}
6514 	skb->protocol = next_proto;
6515 
6516 	return 0;
6517 }
6518 EXPORT_SYMBOL_GPL(skb_mpls_pop);
6519 
6520 /**
6521  * skb_mpls_update_lse() - modify outermost MPLS header and update csum
6522  *
6523  * @skb: buffer
6524  * @mpls_lse: new MPLS label stack entry to update to
6525  *
6526  * Expects skb->data at mac header.
6527  *
6528  * Returns 0 on success, -errno otherwise.
6529  */
skb_mpls_update_lse(struct sk_buff * skb,__be32 mpls_lse)6530 int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse)
6531 {
6532 	int err;
6533 
6534 	if (unlikely(!eth_p_mpls(skb->protocol)))
6535 		return -EINVAL;
6536 
6537 	err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
6538 	if (unlikely(err))
6539 		return err;
6540 
6541 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
6542 		__be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse };
6543 
6544 		skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
6545 	}
6546 
6547 	mpls_hdr(skb)->label_stack_entry = mpls_lse;
6548 
6549 	return 0;
6550 }
6551 EXPORT_SYMBOL_GPL(skb_mpls_update_lse);
6552 
6553 /**
6554  * skb_mpls_dec_ttl() - decrement the TTL of the outermost MPLS header
6555  *
6556  * @skb: buffer
6557  *
6558  * Expects skb->data at mac header.
6559  *
6560  * Returns 0 on success, -errno otherwise.
6561  */
skb_mpls_dec_ttl(struct sk_buff * skb)6562 int skb_mpls_dec_ttl(struct sk_buff *skb)
6563 {
6564 	u32 lse;
6565 	u8 ttl;
6566 
6567 	if (unlikely(!eth_p_mpls(skb->protocol)))
6568 		return -EINVAL;
6569 
6570 	if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
6571 		return -ENOMEM;
6572 
6573 	lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
6574 	ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
6575 	if (!--ttl)
6576 		return -EINVAL;
6577 
6578 	lse &= ~MPLS_LS_TTL_MASK;
6579 	lse |= ttl << MPLS_LS_TTL_SHIFT;
6580 
6581 	return skb_mpls_update_lse(skb, cpu_to_be32(lse));
6582 }
6583 EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl);
6584 
6585 /**
6586  * alloc_skb_with_frags - allocate skb with page frags
6587  *
6588  * @header_len: size of linear part
6589  * @data_len: needed length in frags
6590  * @order: max page order desired.
6591  * @errcode: pointer to error code if any
6592  * @gfp_mask: allocation mask
6593  *
6594  * This can be used to allocate a paged skb, given a maximal order for frags.
6595  */
alloc_skb_with_frags(unsigned long header_len,unsigned long data_len,int order,int * errcode,gfp_t gfp_mask)6596 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
6597 				     unsigned long data_len,
6598 				     int order,
6599 				     int *errcode,
6600 				     gfp_t gfp_mask)
6601 {
6602 	unsigned long chunk;
6603 	struct sk_buff *skb;
6604 	struct page *page;
6605 	int nr_frags = 0;
6606 
6607 	*errcode = -EMSGSIZE;
6608 	if (unlikely(data_len > MAX_SKB_FRAGS * (PAGE_SIZE << order)))
6609 		return NULL;
6610 
6611 	*errcode = -ENOBUFS;
6612 	skb = alloc_skb(header_len, gfp_mask);
6613 	if (!skb)
6614 		return NULL;
6615 
6616 	while (data_len) {
6617 		if (nr_frags == MAX_SKB_FRAGS - 1)
6618 			goto failure;
6619 		while (order && PAGE_ALIGN(data_len) < (PAGE_SIZE << order))
6620 			order--;
6621 
6622 		if (order) {
6623 			page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
6624 					   __GFP_COMP |
6625 					   __GFP_NOWARN,
6626 					   order);
6627 			if (!page) {
6628 				order--;
6629 				continue;
6630 			}
6631 		} else {
6632 			page = alloc_page(gfp_mask);
6633 			if (!page)
6634 				goto failure;
6635 		}
6636 		chunk = min_t(unsigned long, data_len,
6637 			      PAGE_SIZE << order);
6638 		skb_fill_page_desc(skb, nr_frags, page, 0, chunk);
6639 		nr_frags++;
6640 		skb->truesize += (PAGE_SIZE << order);
6641 		data_len -= chunk;
6642 	}
6643 	return skb;
6644 
6645 failure:
6646 	kfree_skb(skb);
6647 	return NULL;
6648 }
6649 EXPORT_SYMBOL(alloc_skb_with_frags);
6650 
6651 /* carve out the first off bytes from skb when off < headlen */
pskb_carve_inside_header(struct sk_buff * skb,const u32 off,const int headlen,gfp_t gfp_mask)6652 static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
6653 				    const int headlen, gfp_t gfp_mask)
6654 {
6655 	int i;
6656 	unsigned int size = skb_end_offset(skb);
6657 	int new_hlen = headlen - off;
6658 	u8 *data;
6659 
6660 	if (skb_pfmemalloc(skb))
6661 		gfp_mask |= __GFP_MEMALLOC;
6662 
6663 	data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
6664 	if (!data)
6665 		return -ENOMEM;
6666 	size = SKB_WITH_OVERHEAD(size);
6667 
6668 	/* Copy real data, and all frags */
6669 	skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
6670 	skb->len -= off;
6671 
6672 	memcpy((struct skb_shared_info *)(data + size),
6673 	       skb_shinfo(skb),
6674 	       offsetof(struct skb_shared_info,
6675 			frags[skb_shinfo(skb)->nr_frags]));
6676 	if (skb_cloned(skb)) {
6677 		/* drop the old head gracefully */
6678 		if (skb_orphan_frags(skb, gfp_mask)) {
6679 			skb_kfree_head(data, size);
6680 			return -ENOMEM;
6681 		}
6682 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
6683 			skb_frag_ref(skb, i);
6684 		if (skb_has_frag_list(skb))
6685 			skb_clone_fraglist(skb);
6686 		skb_release_data(skb, SKB_CONSUMED);
6687 	} else {
6688 		/* we can reuse existing recount- all we did was
6689 		 * relocate values
6690 		 */
6691 		skb_free_head(skb);
6692 	}
6693 
6694 	skb->head = data;
6695 	skb->data = data;
6696 	skb->head_frag = 0;
6697 	skb_set_end_offset(skb, size);
6698 	skb_set_tail_pointer(skb, skb_headlen(skb));
6699 	skb_headers_offset_update(skb, 0);
6700 	skb->cloned = 0;
6701 	skb->hdr_len = 0;
6702 	skb->nohdr = 0;
6703 	atomic_set(&skb_shinfo(skb)->dataref, 1);
6704 
6705 	return 0;
6706 }
6707 
6708 static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
6709 
6710 /* carve out the first eat bytes from skb's frag_list. May recurse into
6711  * pskb_carve()
6712  */
pskb_carve_frag_list(struct sk_buff * skb,struct skb_shared_info * shinfo,int eat,gfp_t gfp_mask)6713 static int pskb_carve_frag_list(struct sk_buff *skb,
6714 				struct skb_shared_info *shinfo, int eat,
6715 				gfp_t gfp_mask)
6716 {
6717 	struct sk_buff *list = shinfo->frag_list;
6718 	struct sk_buff *clone = NULL;
6719 	struct sk_buff *insp = NULL;
6720 
6721 	do {
6722 		if (!list) {
6723 			pr_err("Not enough bytes to eat. Want %d\n", eat);
6724 			return -EFAULT;
6725 		}
6726 		if (list->len <= eat) {
6727 			/* Eaten as whole. */
6728 			eat -= list->len;
6729 			list = list->next;
6730 			insp = list;
6731 		} else {
6732 			/* Eaten partially. */
6733 			if (skb_shared(list)) {
6734 				clone = skb_clone(list, gfp_mask);
6735 				if (!clone)
6736 					return -ENOMEM;
6737 				insp = list->next;
6738 				list = clone;
6739 			} else {
6740 				/* This may be pulled without problems. */
6741 				insp = list;
6742 			}
6743 			if (pskb_carve(list, eat, gfp_mask) < 0) {
6744 				kfree_skb(clone);
6745 				return -ENOMEM;
6746 			}
6747 			break;
6748 		}
6749 	} while (eat);
6750 
6751 	/* Free pulled out fragments. */
6752 	while ((list = shinfo->frag_list) != insp) {
6753 		shinfo->frag_list = list->next;
6754 		consume_skb(list);
6755 	}
6756 	/* And insert new clone at head. */
6757 	if (clone) {
6758 		clone->next = list;
6759 		shinfo->frag_list = clone;
6760 	}
6761 	return 0;
6762 }
6763 
6764 /* carve off first len bytes from skb. Split line (off) is in the
6765  * non-linear part of skb
6766  */
pskb_carve_inside_nonlinear(struct sk_buff * skb,const u32 off,int pos,gfp_t gfp_mask)6767 static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
6768 				       int pos, gfp_t gfp_mask)
6769 {
6770 	int i, k = 0;
6771 	unsigned int size = skb_end_offset(skb);
6772 	u8 *data;
6773 	const int nfrags = skb_shinfo(skb)->nr_frags;
6774 	struct skb_shared_info *shinfo;
6775 
6776 	if (skb_pfmemalloc(skb))
6777 		gfp_mask |= __GFP_MEMALLOC;
6778 
6779 	data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
6780 	if (!data)
6781 		return -ENOMEM;
6782 	size = SKB_WITH_OVERHEAD(size);
6783 
6784 	memcpy((struct skb_shared_info *)(data + size),
6785 	       skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0]));
6786 	if (skb_orphan_frags(skb, gfp_mask)) {
6787 		skb_kfree_head(data, size);
6788 		return -ENOMEM;
6789 	}
6790 	shinfo = (struct skb_shared_info *)(data + size);
6791 	for (i = 0; i < nfrags; i++) {
6792 		int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
6793 
6794 		if (pos + fsize > off) {
6795 			shinfo->frags[k] = skb_shinfo(skb)->frags[i];
6796 
6797 			if (pos < off) {
6798 				/* Split frag.
6799 				 * We have two variants in this case:
6800 				 * 1. Move all the frag to the second
6801 				 *    part, if it is possible. F.e.
6802 				 *    this approach is mandatory for TUX,
6803 				 *    where splitting is expensive.
6804 				 * 2. Split is accurately. We make this.
6805 				 */
6806 				skb_frag_off_add(&shinfo->frags[0], off - pos);
6807 				skb_frag_size_sub(&shinfo->frags[0], off - pos);
6808 			}
6809 			skb_frag_ref(skb, i);
6810 			k++;
6811 		}
6812 		pos += fsize;
6813 	}
6814 	shinfo->nr_frags = k;
6815 	if (skb_has_frag_list(skb))
6816 		skb_clone_fraglist(skb);
6817 
6818 	/* split line is in frag list */
6819 	if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
6820 		/* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
6821 		if (skb_has_frag_list(skb))
6822 			kfree_skb_list(skb_shinfo(skb)->frag_list);
6823 		skb_kfree_head(data, size);
6824 		return -ENOMEM;
6825 	}
6826 	skb_release_data(skb, SKB_CONSUMED);
6827 
6828 	skb->head = data;
6829 	skb->head_frag = 0;
6830 	skb->data = data;
6831 	skb_set_end_offset(skb, size);
6832 	skb_reset_tail_pointer(skb);
6833 	skb_headers_offset_update(skb, 0);
6834 	skb->cloned   = 0;
6835 	skb->hdr_len  = 0;
6836 	skb->nohdr    = 0;
6837 	skb->len -= off;
6838 	skb->data_len = skb->len;
6839 	atomic_set(&skb_shinfo(skb)->dataref, 1);
6840 	return 0;
6841 }
6842 
6843 /* remove len bytes from the beginning of the skb */
pskb_carve(struct sk_buff * skb,const u32 len,gfp_t gfp)6844 static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
6845 {
6846 	int headlen = skb_headlen(skb);
6847 
6848 	if (len < headlen)
6849 		return pskb_carve_inside_header(skb, len, headlen, gfp);
6850 	else
6851 		return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
6852 }
6853 
6854 /* Extract to_copy bytes starting at off from skb, and return this in
6855  * a new skb
6856  */
pskb_extract(struct sk_buff * skb,int off,int to_copy,gfp_t gfp)6857 struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
6858 			     int to_copy, gfp_t gfp)
6859 {
6860 	struct sk_buff  *clone = skb_clone(skb, gfp);
6861 
6862 	if (!clone)
6863 		return NULL;
6864 
6865 	if (pskb_carve(clone, off, gfp) < 0 ||
6866 	    pskb_trim(clone, to_copy)) {
6867 		kfree_skb(clone);
6868 		return NULL;
6869 	}
6870 	return clone;
6871 }
6872 EXPORT_SYMBOL(pskb_extract);
6873 
6874 /**
6875  * skb_condense - try to get rid of fragments/frag_list if possible
6876  * @skb: buffer
6877  *
6878  * Can be used to save memory before skb is added to a busy queue.
6879  * If packet has bytes in frags and enough tail room in skb->head,
6880  * pull all of them, so that we can free the frags right now and adjust
6881  * truesize.
6882  * Notes:
6883  *	We do not reallocate skb->head thus can not fail.
6884  *	Caller must re-evaluate skb->truesize if needed.
6885  */
skb_condense(struct sk_buff * skb)6886 void skb_condense(struct sk_buff *skb)
6887 {
6888 	if (skb->data_len) {
6889 		if (skb->data_len > skb->end - skb->tail ||
6890 		    skb_cloned(skb) || !skb_frags_readable(skb))
6891 			return;
6892 
6893 		/* Nice, we can free page frag(s) right now */
6894 		__pskb_pull_tail(skb, skb->data_len);
6895 	}
6896 	/* At this point, skb->truesize might be over estimated,
6897 	 * because skb had a fragment, and fragments do not tell
6898 	 * their truesize.
6899 	 * When we pulled its content into skb->head, fragment
6900 	 * was freed, but __pskb_pull_tail() could not possibly
6901 	 * adjust skb->truesize, not knowing the frag truesize.
6902 	 */
6903 	skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
6904 }
6905 EXPORT_SYMBOL(skb_condense);
6906 
6907 #ifdef CONFIG_SKB_EXTENSIONS
skb_ext_get_ptr(struct skb_ext * ext,enum skb_ext_id id)6908 static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
6909 {
6910 	return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE);
6911 }
6912 
6913 /**
6914  * __skb_ext_alloc - allocate a new skb extensions storage
6915  *
6916  * @flags: See kmalloc().
6917  *
6918  * Returns the newly allocated pointer. The pointer can later attached to a
6919  * skb via __skb_ext_set().
6920  * Note: caller must handle the skb_ext as an opaque data.
6921  */
__skb_ext_alloc(gfp_t flags)6922 struct skb_ext *__skb_ext_alloc(gfp_t flags)
6923 {
6924 	struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, flags);
6925 
6926 	if (new) {
6927 		memset(new->offset, 0, sizeof(new->offset));
6928 		refcount_set(&new->refcnt, 1);
6929 	}
6930 
6931 	return new;
6932 }
6933 
skb_ext_maybe_cow(struct skb_ext * old,unsigned int old_active)6934 static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old,
6935 					 unsigned int old_active)
6936 {
6937 	struct skb_ext *new;
6938 
6939 	if (refcount_read(&old->refcnt) == 1)
6940 		return old;
6941 
6942 	new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
6943 	if (!new)
6944 		return NULL;
6945 
6946 	memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE);
6947 	refcount_set(&new->refcnt, 1);
6948 
6949 #ifdef CONFIG_XFRM
6950 	if (old_active & (1 << SKB_EXT_SEC_PATH)) {
6951 		struct sec_path *sp = skb_ext_get_ptr(old, SKB_EXT_SEC_PATH);
6952 		unsigned int i;
6953 
6954 		for (i = 0; i < sp->len; i++)
6955 			xfrm_state_hold(sp->xvec[i]);
6956 	}
6957 #endif
6958 #ifdef CONFIG_MCTP_FLOWS
6959 	if (old_active & (1 << SKB_EXT_MCTP)) {
6960 		struct mctp_flow *flow = skb_ext_get_ptr(old, SKB_EXT_MCTP);
6961 
6962 		if (flow->key)
6963 			refcount_inc(&flow->key->refs);
6964 	}
6965 #endif
6966 	__skb_ext_put(old);
6967 	return new;
6968 }
6969 
6970 /**
6971  * __skb_ext_set - attach the specified extension storage to this skb
6972  * @skb: buffer
6973  * @id: extension id
6974  * @ext: extension storage previously allocated via __skb_ext_alloc()
6975  *
6976  * Existing extensions, if any, are cleared.
6977  *
6978  * Returns the pointer to the extension.
6979  */
__skb_ext_set(struct sk_buff * skb,enum skb_ext_id id,struct skb_ext * ext)6980 void *__skb_ext_set(struct sk_buff *skb, enum skb_ext_id id,
6981 		    struct skb_ext *ext)
6982 {
6983 	unsigned int newlen, newoff = SKB_EXT_CHUNKSIZEOF(*ext);
6984 
6985 	skb_ext_put(skb);
6986 	newlen = newoff + skb_ext_type_len[id];
6987 	ext->chunks = newlen;
6988 	ext->offset[id] = newoff;
6989 	skb->extensions = ext;
6990 	skb->active_extensions = 1 << id;
6991 	return skb_ext_get_ptr(ext, id);
6992 }
6993 
6994 /**
6995  * skb_ext_add - allocate space for given extension, COW if needed
6996  * @skb: buffer
6997  * @id: extension to allocate space for
6998  *
6999  * Allocates enough space for the given extension.
7000  * If the extension is already present, a pointer to that extension
7001  * is returned.
7002  *
7003  * If the skb was cloned, COW applies and the returned memory can be
7004  * modified without changing the extension space of clones buffers.
7005  *
7006  * Returns pointer to the extension or NULL on allocation failure.
7007  */
skb_ext_add(struct sk_buff * skb,enum skb_ext_id id)7008 void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id)
7009 {
7010 	struct skb_ext *new, *old = NULL;
7011 	unsigned int newlen, newoff;
7012 
7013 	if (skb->active_extensions) {
7014 		old = skb->extensions;
7015 
7016 		new = skb_ext_maybe_cow(old, skb->active_extensions);
7017 		if (!new)
7018 			return NULL;
7019 
7020 		if (__skb_ext_exist(new, id))
7021 			goto set_active;
7022 
7023 		newoff = new->chunks;
7024 	} else {
7025 		newoff = SKB_EXT_CHUNKSIZEOF(*new);
7026 
7027 		new = __skb_ext_alloc(GFP_ATOMIC);
7028 		if (!new)
7029 			return NULL;
7030 	}
7031 
7032 	newlen = newoff + skb_ext_type_len[id];
7033 	new->chunks = newlen;
7034 	new->offset[id] = newoff;
7035 set_active:
7036 	skb->slow_gro = 1;
7037 	skb->extensions = new;
7038 	skb->active_extensions |= 1 << id;
7039 	return skb_ext_get_ptr(new, id);
7040 }
7041 EXPORT_SYMBOL(skb_ext_add);
7042 
7043 #ifdef CONFIG_XFRM
skb_ext_put_sp(struct sec_path * sp)7044 static void skb_ext_put_sp(struct sec_path *sp)
7045 {
7046 	unsigned int i;
7047 
7048 	for (i = 0; i < sp->len; i++)
7049 		xfrm_state_put(sp->xvec[i]);
7050 }
7051 #endif
7052 
7053 #ifdef CONFIG_MCTP_FLOWS
skb_ext_put_mctp(struct mctp_flow * flow)7054 static void skb_ext_put_mctp(struct mctp_flow *flow)
7055 {
7056 	if (flow->key)
7057 		mctp_key_unref(flow->key);
7058 }
7059 #endif
7060 
__skb_ext_del(struct sk_buff * skb,enum skb_ext_id id)7061 void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
7062 {
7063 	struct skb_ext *ext = skb->extensions;
7064 
7065 	skb->active_extensions &= ~(1 << id);
7066 	if (skb->active_extensions == 0) {
7067 		skb->extensions = NULL;
7068 		__skb_ext_put(ext);
7069 #ifdef CONFIG_XFRM
7070 	} else if (id == SKB_EXT_SEC_PATH &&
7071 		   refcount_read(&ext->refcnt) == 1) {
7072 		struct sec_path *sp = skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH);
7073 
7074 		skb_ext_put_sp(sp);
7075 		sp->len = 0;
7076 #endif
7077 	}
7078 }
7079 EXPORT_SYMBOL(__skb_ext_del);
7080 
__skb_ext_put(struct skb_ext * ext)7081 void __skb_ext_put(struct skb_ext *ext)
7082 {
7083 	/* If this is last clone, nothing can increment
7084 	 * it after check passes.  Avoids one atomic op.
7085 	 */
7086 	if (refcount_read(&ext->refcnt) == 1)
7087 		goto free_now;
7088 
7089 	if (!refcount_dec_and_test(&ext->refcnt))
7090 		return;
7091 free_now:
7092 #ifdef CONFIG_XFRM
7093 	if (__skb_ext_exist(ext, SKB_EXT_SEC_PATH))
7094 		skb_ext_put_sp(skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH));
7095 #endif
7096 #ifdef CONFIG_MCTP_FLOWS
7097 	if (__skb_ext_exist(ext, SKB_EXT_MCTP))
7098 		skb_ext_put_mctp(skb_ext_get_ptr(ext, SKB_EXT_MCTP));
7099 #endif
7100 
7101 	kmem_cache_free(skbuff_ext_cache, ext);
7102 }
7103 EXPORT_SYMBOL(__skb_ext_put);
7104 #endif /* CONFIG_SKB_EXTENSIONS */
7105 
kfree_skb_napi_cache(struct sk_buff * skb)7106 static void kfree_skb_napi_cache(struct sk_buff *skb)
7107 {
7108 	/* if SKB is a clone, don't handle this case */
7109 	if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
7110 		__kfree_skb(skb);
7111 		return;
7112 	}
7113 
7114 	local_bh_disable();
7115 	__napi_kfree_skb(skb, SKB_CONSUMED);
7116 	local_bh_enable();
7117 }
7118 
7119 /**
7120  * skb_attempt_defer_free - queue skb for remote freeing
7121  * @skb: buffer
7122  *
7123  * Put @skb in a per-cpu list, using the cpu which
7124  * allocated the skb/pages to reduce false sharing
7125  * and memory zone spinlock contention.
7126  */
skb_attempt_defer_free(struct sk_buff * skb)7127 void skb_attempt_defer_free(struct sk_buff *skb)
7128 {
7129 	int cpu = skb->alloc_cpu;
7130 	struct softnet_data *sd;
7131 	unsigned int defer_max;
7132 	bool kick;
7133 
7134 	if (cpu == raw_smp_processor_id() ||
7135 	    WARN_ON_ONCE(cpu >= nr_cpu_ids) ||
7136 	    !cpu_online(cpu)) {
7137 nodefer:	kfree_skb_napi_cache(skb);
7138 		return;
7139 	}
7140 
7141 	DEBUG_NET_WARN_ON_ONCE(skb_dst(skb));
7142 	DEBUG_NET_WARN_ON_ONCE(skb->destructor);
7143 
7144 	sd = &per_cpu(softnet_data, cpu);
7145 	defer_max = READ_ONCE(net_hotdata.sysctl_skb_defer_max);
7146 	if (READ_ONCE(sd->defer_count) >= defer_max)
7147 		goto nodefer;
7148 
7149 	spin_lock_bh(&sd->defer_lock);
7150 	/* Send an IPI every time queue reaches half capacity. */
7151 	kick = sd->defer_count == (defer_max >> 1);
7152 	/* Paired with the READ_ONCE() few lines above */
7153 	WRITE_ONCE(sd->defer_count, sd->defer_count + 1);
7154 
7155 	skb->next = sd->defer_list;
7156 	/* Paired with READ_ONCE() in skb_defer_free_flush() */
7157 	WRITE_ONCE(sd->defer_list, skb);
7158 	spin_unlock_bh(&sd->defer_lock);
7159 
7160 	/* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU
7161 	 * if we are unlucky enough (this seems very unlikely).
7162 	 */
7163 	if (unlikely(kick))
7164 		kick_defer_list_purge(sd, cpu);
7165 }
7166 
skb_splice_csum_page(struct sk_buff * skb,struct page * page,size_t offset,size_t len)7167 static void skb_splice_csum_page(struct sk_buff *skb, struct page *page,
7168 				 size_t offset, size_t len)
7169 {
7170 	const char *kaddr;
7171 	__wsum csum;
7172 
7173 	kaddr = kmap_local_page(page);
7174 	csum = csum_partial(kaddr + offset, len, 0);
7175 	kunmap_local(kaddr);
7176 	skb->csum = csum_block_add(skb->csum, csum, skb->len);
7177 }
7178 
7179 /**
7180  * skb_splice_from_iter - Splice (or copy) pages to skbuff
7181  * @skb: The buffer to add pages to
7182  * @iter: Iterator representing the pages to be added
7183  * @maxsize: Maximum amount of pages to be added
7184  * @gfp: Allocation flags
7185  *
7186  * This is a common helper function for supporting MSG_SPLICE_PAGES.  It
7187  * extracts pages from an iterator and adds them to the socket buffer if
7188  * possible, copying them to fragments if not possible (such as if they're slab
7189  * pages).
7190  *
7191  * Returns the amount of data spliced/copied or -EMSGSIZE if there's
7192  * insufficient space in the buffer to transfer anything.
7193  */
skb_splice_from_iter(struct sk_buff * skb,struct iov_iter * iter,ssize_t maxsize,gfp_t gfp)7194 ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,
7195 			     ssize_t maxsize, gfp_t gfp)
7196 {
7197 	size_t frag_limit = READ_ONCE(net_hotdata.sysctl_max_skb_frags);
7198 	struct page *pages[8], **ppages = pages;
7199 	ssize_t spliced = 0, ret = 0;
7200 	unsigned int i;
7201 
7202 	while (iter->count > 0) {
7203 		ssize_t space, nr, len;
7204 		size_t off;
7205 
7206 		ret = -EMSGSIZE;
7207 		space = frag_limit - skb_shinfo(skb)->nr_frags;
7208 		if (space < 0)
7209 			break;
7210 
7211 		/* We might be able to coalesce without increasing nr_frags */
7212 		nr = clamp_t(size_t, space, 1, ARRAY_SIZE(pages));
7213 
7214 		len = iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off);
7215 		if (len <= 0) {
7216 			ret = len ?: -EIO;
7217 			break;
7218 		}
7219 
7220 		i = 0;
7221 		do {
7222 			struct page *page = pages[i++];
7223 			size_t part = min_t(size_t, PAGE_SIZE - off, len);
7224 
7225 			ret = -EIO;
7226 			if (WARN_ON_ONCE(!sendpage_ok(page)))
7227 				goto out;
7228 
7229 			ret = skb_append_pagefrags(skb, page, off, part,
7230 						   frag_limit);
7231 			if (ret < 0) {
7232 				iov_iter_revert(iter, len);
7233 				goto out;
7234 			}
7235 
7236 			if (skb->ip_summed == CHECKSUM_NONE)
7237 				skb_splice_csum_page(skb, page, off, part);
7238 
7239 			off = 0;
7240 			spliced += part;
7241 			maxsize -= part;
7242 			len -= part;
7243 		} while (len > 0);
7244 
7245 		if (maxsize <= 0)
7246 			break;
7247 	}
7248 
7249 out:
7250 	skb_len_add(skb, spliced);
7251 	return spliced ?: ret;
7252 }
7253 EXPORT_SYMBOL(skb_splice_from_iter);
7254 
7255 static __always_inline
memcpy_from_iter_csum(void * iter_from,size_t progress,size_t len,void * to,void * priv2)7256 size_t memcpy_from_iter_csum(void *iter_from, size_t progress,
7257 			     size_t len, void *to, void *priv2)
7258 {
7259 	__wsum *csum = priv2;
7260 	__wsum next = csum_partial_copy_nocheck(iter_from, to + progress, len);
7261 
7262 	*csum = csum_block_add(*csum, next, progress);
7263 	return 0;
7264 }
7265 
7266 static __always_inline
copy_from_user_iter_csum(void __user * iter_from,size_t progress,size_t len,void * to,void * priv2)7267 size_t copy_from_user_iter_csum(void __user *iter_from, size_t progress,
7268 				size_t len, void *to, void *priv2)
7269 {
7270 	__wsum next, *csum = priv2;
7271 
7272 	next = csum_and_copy_from_user(iter_from, to + progress, len);
7273 	*csum = csum_block_add(*csum, next, progress);
7274 	return next ? 0 : len;
7275 }
7276 
csum_and_copy_from_iter_full(void * addr,size_t bytes,__wsum * csum,struct iov_iter * i)7277 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
7278 				  __wsum *csum, struct iov_iter *i)
7279 {
7280 	size_t copied;
7281 
7282 	if (WARN_ON_ONCE(!i->data_source))
7283 		return false;
7284 	copied = iterate_and_advance2(i, bytes, addr, csum,
7285 				      copy_from_user_iter_csum,
7286 				      memcpy_from_iter_csum);
7287 	if (likely(copied == bytes))
7288 		return true;
7289 	iov_iter_revert(i, copied);
7290 	return false;
7291 }
7292 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
7293