1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * IPV4 GSO/GRO offload support
4 * Linux INET implementation
5 *
6 * TCPv4 GSO/GRO support
7 */
8
9 #include <linux/indirect_call_wrapper.h>
10 #include <linux/skbuff.h>
11 #include <net/gro.h>
12 #include <net/gso.h>
13 #include <net/tcp.h>
14 #include <net/protocol.h>
15
tcp_gso_tstamp(struct sk_buff * skb,unsigned int ts_seq,unsigned int seq,unsigned int mss)16 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
17 unsigned int seq, unsigned int mss)
18 {
19 while (skb) {
20 if (before(ts_seq, seq + mss)) {
21 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
22 skb_shinfo(skb)->tskey = ts_seq;
23 return;
24 }
25
26 skb = skb->next;
27 seq += mss;
28 }
29 }
30
__tcpv4_gso_segment_csum(struct sk_buff * seg,__be32 * oldip,__be32 newip,__be16 * oldport,__be16 newport)31 static void __tcpv4_gso_segment_csum(struct sk_buff *seg,
32 __be32 *oldip, __be32 newip,
33 __be16 *oldport, __be16 newport)
34 {
35 struct tcphdr *th;
36 struct iphdr *iph;
37
38 if (*oldip == newip && *oldport == newport)
39 return;
40
41 th = tcp_hdr(seg);
42 iph = ip_hdr(seg);
43
44 inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true);
45 inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
46 *oldport = newport;
47
48 csum_replace4(&iph->check, *oldip, newip);
49 *oldip = newip;
50 }
51
__tcpv4_gso_segment_list_csum(struct sk_buff * segs)52 static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs)
53 {
54 const struct tcphdr *th;
55 const struct iphdr *iph;
56 struct sk_buff *seg;
57 struct tcphdr *th2;
58 struct iphdr *iph2;
59
60 seg = segs;
61 th = tcp_hdr(seg);
62 iph = ip_hdr(seg);
63 th2 = tcp_hdr(seg->next);
64 iph2 = ip_hdr(seg->next);
65
66 if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
67 iph->daddr == iph2->daddr && iph->saddr == iph2->saddr)
68 return segs;
69
70 while ((seg = seg->next)) {
71 th2 = tcp_hdr(seg);
72 iph2 = ip_hdr(seg);
73
74 __tcpv4_gso_segment_csum(seg,
75 &iph2->saddr, iph->saddr,
76 &th2->source, th->source);
77 __tcpv4_gso_segment_csum(seg,
78 &iph2->daddr, iph->daddr,
79 &th2->dest, th->dest);
80 }
81
82 return segs;
83 }
84
__tcp4_gso_segment_list(struct sk_buff * skb,netdev_features_t features)85 static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb,
86 netdev_features_t features)
87 {
88 skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
89 if (IS_ERR(skb))
90 return skb;
91
92 return __tcpv4_gso_segment_list_csum(skb);
93 }
94
tcp4_gso_segment(struct sk_buff * skb,netdev_features_t features)95 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
96 netdev_features_t features)
97 {
98 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
99 return ERR_PTR(-EINVAL);
100
101 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
102 return ERR_PTR(-EINVAL);
103
104 if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)
105 return __tcp4_gso_segment_list(skb, features);
106
107 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
108 const struct iphdr *iph = ip_hdr(skb);
109 struct tcphdr *th = tcp_hdr(skb);
110
111 /* Set up checksum pseudo header, usually expect stack to
112 * have done this already.
113 */
114
115 th->check = 0;
116 skb->ip_summed = CHECKSUM_PARTIAL;
117 __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
118 }
119
120 return tcp_gso_segment(skb, features);
121 }
122
tcp_gso_segment(struct sk_buff * skb,netdev_features_t features)123 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
124 netdev_features_t features)
125 {
126 struct sk_buff *segs = ERR_PTR(-EINVAL);
127 unsigned int sum_truesize = 0;
128 struct tcphdr *th;
129 unsigned int thlen;
130 unsigned int seq;
131 unsigned int oldlen;
132 unsigned int mss;
133 struct sk_buff *gso_skb = skb;
134 __sum16 newcheck;
135 bool ooo_okay, copy_destructor;
136 __wsum delta;
137
138 th = tcp_hdr(skb);
139 thlen = th->doff * 4;
140 if (thlen < sizeof(*th))
141 goto out;
142
143 if (!pskb_may_pull(skb, thlen))
144 goto out;
145
146 oldlen = ~skb->len;
147 __skb_pull(skb, thlen);
148
149 mss = skb_shinfo(skb)->gso_size;
150 if (unlikely(skb->len <= mss))
151 goto out;
152
153 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
154 /* Packet is from an untrusted source, reset gso_segs. */
155
156 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
157
158 segs = NULL;
159 goto out;
160 }
161
162 copy_destructor = gso_skb->destructor == tcp_wfree;
163 ooo_okay = gso_skb->ooo_okay;
164 /* All segments but the first should have ooo_okay cleared */
165 skb->ooo_okay = 0;
166
167 segs = skb_segment(skb, features);
168 if (IS_ERR(segs))
169 goto out;
170
171 /* Only first segment might have ooo_okay set */
172 segs->ooo_okay = ooo_okay;
173
174 /* GSO partial and frag_list segmentation only requires splitting
175 * the frame into an MSS multiple and possibly a remainder, both
176 * cases return a GSO skb. So update the mss now.
177 */
178 if (skb_is_gso(segs))
179 mss *= skb_shinfo(segs)->gso_segs;
180
181 delta = (__force __wsum)htonl(oldlen + thlen + mss);
182
183 skb = segs;
184 th = tcp_hdr(skb);
185 seq = ntohl(th->seq);
186
187 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
188 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
189
190 newcheck = ~csum_fold(csum_add(csum_unfold(th->check), delta));
191
192 while (skb->next) {
193 th->fin = th->psh = 0;
194 th->check = newcheck;
195
196 if (skb->ip_summed == CHECKSUM_PARTIAL)
197 gso_reset_checksum(skb, ~th->check);
198 else
199 th->check = gso_make_checksum(skb, ~th->check);
200
201 seq += mss;
202 if (copy_destructor) {
203 skb->destructor = gso_skb->destructor;
204 skb->sk = gso_skb->sk;
205 sum_truesize += skb->truesize;
206 }
207 skb = skb->next;
208 th = tcp_hdr(skb);
209
210 th->seq = htonl(seq);
211 th->cwr = 0;
212 }
213
214 /* Following permits TCP Small Queues to work well with GSO :
215 * The callback to TCP stack will be called at the time last frag
216 * is freed at TX completion, and not right now when gso_skb
217 * is freed by GSO engine
218 */
219 if (copy_destructor) {
220 int delta;
221
222 swap(gso_skb->sk, skb->sk);
223 swap(gso_skb->destructor, skb->destructor);
224 sum_truesize += skb->truesize;
225 delta = sum_truesize - gso_skb->truesize;
226 /* In some pathological cases, delta can be negative.
227 * We need to either use refcount_add() or refcount_sub_and_test()
228 */
229 if (likely(delta >= 0))
230 refcount_add(delta, &skb->sk->sk_wmem_alloc);
231 else
232 WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc));
233 }
234
235 delta = (__force __wsum)htonl(oldlen +
236 (skb_tail_pointer(skb) -
237 skb_transport_header(skb)) +
238 skb->data_len);
239 th->check = ~csum_fold(csum_add(csum_unfold(th->check), delta));
240 if (skb->ip_summed == CHECKSUM_PARTIAL)
241 gso_reset_checksum(skb, ~th->check);
242 else
243 th->check = gso_make_checksum(skb, ~th->check);
244 out:
245 return segs;
246 }
247
tcp_gro_lookup(struct list_head * head,struct tcphdr * th)248 struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th)
249 {
250 struct tcphdr *th2;
251 struct sk_buff *p;
252
253 list_for_each_entry(p, head, list) {
254 if (!NAPI_GRO_CB(p)->same_flow)
255 continue;
256
257 th2 = tcp_hdr(p);
258 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
259 NAPI_GRO_CB(p)->same_flow = 0;
260 continue;
261 }
262
263 return p;
264 }
265
266 return NULL;
267 }
268
tcp_gro_pull_header(struct sk_buff * skb)269 struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb)
270 {
271 unsigned int thlen, hlen, off;
272 struct tcphdr *th;
273
274 off = skb_gro_offset(skb);
275 hlen = off + sizeof(*th);
276 th = skb_gro_header(skb, hlen, off);
277 if (unlikely(!th))
278 return NULL;
279
280 thlen = th->doff * 4;
281 if (thlen < sizeof(*th))
282 return NULL;
283
284 hlen = off + thlen;
285 if (!skb_gro_may_pull(skb, hlen)) {
286 th = skb_gro_header_slow(skb, hlen, off);
287 if (unlikely(!th))
288 return NULL;
289 }
290
291 skb_gro_pull(skb, thlen);
292
293 return th;
294 }
295
tcp_gro_receive(struct list_head * head,struct sk_buff * skb,struct tcphdr * th)296 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
297 struct tcphdr *th)
298 {
299 unsigned int thlen = th->doff * 4;
300 struct sk_buff *pp = NULL;
301 struct sk_buff *p;
302 struct tcphdr *th2;
303 unsigned int len;
304 __be32 flags;
305 unsigned int mss = 1;
306 int flush = 1;
307 int i;
308
309 len = skb_gro_len(skb);
310 flags = tcp_flag_word(th);
311
312 p = tcp_gro_lookup(head, th);
313 if (!p)
314 goto out_check_final;
315
316 th2 = tcp_hdr(p);
317 flush = (__force int)(flags & TCP_FLAG_CWR);
318 flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
319 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
320 flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
321 for (i = sizeof(*th); i < thlen; i += 4)
322 flush |= *(u32 *)((u8 *)th + i) ^
323 *(u32 *)((u8 *)th2 + i);
324
325 flush |= gro_receive_network_flush(th, th2, p);
326
327 mss = skb_shinfo(p)->gso_size;
328
329 /* If skb is a GRO packet, make sure its gso_size matches prior packet mss.
330 * If it is a single frame, do not aggregate it if its length
331 * is bigger than our mss.
332 */
333 if (unlikely(skb_is_gso(skb)))
334 flush |= (mss != skb_shinfo(skb)->gso_size);
335 else
336 flush |= (len - 1) >= mss;
337
338 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
339 flush |= skb_cmp_decrypted(p, skb);
340
341 if (unlikely(NAPI_GRO_CB(p)->is_flist)) {
342 flush |= (__force int)(flags ^ tcp_flag_word(th2));
343 flush |= skb->ip_summed != p->ip_summed;
344 flush |= skb->csum_level != p->csum_level;
345 flush |= NAPI_GRO_CB(p)->count >= 64;
346
347 if (flush || skb_gro_receive_list(p, skb))
348 mss = 1;
349
350 goto out_check_final;
351 }
352
353 if (flush || skb_gro_receive(p, skb)) {
354 mss = 1;
355 goto out_check_final;
356 }
357
358 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
359
360 out_check_final:
361 /* Force a flush if last segment is smaller than mss. */
362 if (unlikely(skb_is_gso(skb)))
363 flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size;
364 else
365 flush = len < mss;
366
367 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
368 TCP_FLAG_RST | TCP_FLAG_SYN |
369 TCP_FLAG_FIN));
370
371 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
372 pp = p;
373
374 NAPI_GRO_CB(skb)->flush |= (flush != 0);
375
376 return pp;
377 }
378
tcp_gro_complete(struct sk_buff * skb)379 void tcp_gro_complete(struct sk_buff *skb)
380 {
381 struct tcphdr *th = tcp_hdr(skb);
382 struct skb_shared_info *shinfo;
383
384 if (skb->encapsulation)
385 skb->inner_transport_header = skb->transport_header;
386
387 skb->csum_start = (unsigned char *)th - skb->head;
388 skb->csum_offset = offsetof(struct tcphdr, check);
389 skb->ip_summed = CHECKSUM_PARTIAL;
390
391 shinfo = skb_shinfo(skb);
392 shinfo->gso_segs = NAPI_GRO_CB(skb)->count;
393
394 if (th->cwr)
395 shinfo->gso_type |= SKB_GSO_TCP_ECN;
396 }
397 EXPORT_SYMBOL(tcp_gro_complete);
398
tcp4_check_fraglist_gro(struct list_head * head,struct sk_buff * skb,struct tcphdr * th)399 static void tcp4_check_fraglist_gro(struct list_head *head, struct sk_buff *skb,
400 struct tcphdr *th)
401 {
402 const struct iphdr *iph;
403 struct sk_buff *p;
404 struct sock *sk;
405 struct net *net;
406 int iif, sdif;
407
408 if (likely(!(skb->dev->features & NETIF_F_GRO_FRAGLIST)))
409 return;
410
411 p = tcp_gro_lookup(head, th);
412 if (p) {
413 NAPI_GRO_CB(skb)->is_flist = NAPI_GRO_CB(p)->is_flist;
414 return;
415 }
416
417 inet_get_iif_sdif(skb, &iif, &sdif);
418 iph = skb_gro_network_header(skb);
419 net = dev_net(skb->dev);
420 sk = __inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
421 iph->saddr, th->source,
422 iph->daddr, ntohs(th->dest),
423 iif, sdif);
424 NAPI_GRO_CB(skb)->is_flist = !sk;
425 if (sk)
426 sock_put(sk);
427 }
428
429 INDIRECT_CALLABLE_SCOPE
tcp4_gro_receive(struct list_head * head,struct sk_buff * skb)430 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
431 {
432 struct tcphdr *th;
433
434 /* Don't bother verifying checksum if we're going to flush anyway. */
435 if (!NAPI_GRO_CB(skb)->flush &&
436 skb_gro_checksum_validate(skb, IPPROTO_TCP,
437 inet_gro_compute_pseudo))
438 goto flush;
439
440 th = tcp_gro_pull_header(skb);
441 if (!th)
442 goto flush;
443
444 tcp4_check_fraglist_gro(head, skb, th);
445
446 return tcp_gro_receive(head, skb, th);
447
448 flush:
449 NAPI_GRO_CB(skb)->flush = 1;
450 return NULL;
451 }
452
tcp4_gro_complete(struct sk_buff * skb,int thoff)453 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
454 {
455 const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
456 const struct iphdr *iph = (struct iphdr *)(skb->data + offset);
457 struct tcphdr *th = tcp_hdr(skb);
458
459 if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
460 skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV4;
461 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
462
463 __skb_incr_checksum_unnecessary(skb);
464
465 return 0;
466 }
467
468 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
469 iph->daddr, 0);
470
471 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4 |
472 (NAPI_GRO_CB(skb)->ip_fixedid * SKB_GSO_TCP_FIXEDID);
473
474 tcp_gro_complete(skb);
475 return 0;
476 }
477
tcpv4_offload_init(void)478 int __init tcpv4_offload_init(void)
479 {
480 net_hotdata.tcpv4_offload = (struct net_offload) {
481 .callbacks = {
482 .gso_segment = tcp4_gso_segment,
483 .gro_receive = tcp4_gro_receive,
484 .gro_complete = tcp4_gro_complete,
485 },
486 };
487 return inet_add_offload(&net_hotdata.tcpv4_offload, IPPROTO_TCP);
488 }
489