1 // SPDX-License-Identifier: GPL-2.0
2 /* Multipath TCP
3 *
4 * Copyright (c) 2017 - 2019, Intel Corporation.
5 */
6
7 #define pr_fmt(fmt) "MPTCP: " fmt
8
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/netdevice.h>
12 #include <linux/sched/signal.h>
13 #include <linux/atomic.h>
14 #include <net/sock.h>
15 #include <net/inet_common.h>
16 #include <net/inet_hashtables.h>
17 #include <net/protocol.h>
18 #include <net/tcp.h>
19 #include <net/tcp_states.h>
20 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
21 #include <net/transp_v6.h>
22 #endif
23 #include <net/mptcp.h>
24 #include <net/xfrm.h>
25 #include "protocol.h"
26 #include "mib.h"
27
28 #define CREATE_TRACE_POINTS
29 #include <trace/events/mptcp.h>
30
31 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
32 struct mptcp6_sock {
33 struct mptcp_sock msk;
34 struct ipv6_pinfo np;
35 };
36 #endif
37
38 struct mptcp_skb_cb {
39 u64 map_seq;
40 u64 end_seq;
41 u32 offset;
42 };
43
44 #define MPTCP_SKB_CB(__skb) ((struct mptcp_skb_cb *)&((__skb)->cb[0]))
45
46 static struct percpu_counter mptcp_sockets_allocated;
47
48 static void __mptcp_destroy_sock(struct sock *sk);
49 static void __mptcp_check_send_data_fin(struct sock *sk);
50
51 DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
52 static struct net_device mptcp_napi_dev;
53
54 /* If msk has an initial subflow socket, and the MP_CAPABLE handshake has not
55 * completed yet or has failed, return the subflow socket.
56 * Otherwise return NULL.
57 */
__mptcp_nmpc_socket(const struct mptcp_sock * msk)58 struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk)
59 {
60 if (!msk->subflow || READ_ONCE(msk->can_ack))
61 return NULL;
62
63 return msk->subflow;
64 }
65
66 /* Returns end sequence number of the receiver's advertised window */
mptcp_wnd_end(const struct mptcp_sock * msk)67 static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
68 {
69 return READ_ONCE(msk->wnd_end);
70 }
71
mptcp_is_tcpsk(struct sock * sk)72 static bool mptcp_is_tcpsk(struct sock *sk)
73 {
74 struct socket *sock = sk->sk_socket;
75
76 if (unlikely(sk->sk_prot == &tcp_prot)) {
77 /* we are being invoked after mptcp_accept() has
78 * accepted a non-mp-capable flow: sk is a tcp_sk,
79 * not an mptcp one.
80 *
81 * Hand the socket over to tcp so all further socket ops
82 * bypass mptcp.
83 */
84 sock->ops = &inet_stream_ops;
85 return true;
86 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
87 } else if (unlikely(sk->sk_prot == &tcpv6_prot)) {
88 sock->ops = &inet6_stream_ops;
89 return true;
90 #endif
91 }
92
93 return false;
94 }
95
__mptcp_socket_create(struct mptcp_sock * msk)96 static int __mptcp_socket_create(struct mptcp_sock *msk)
97 {
98 struct mptcp_subflow_context *subflow;
99 struct sock *sk = (struct sock *)msk;
100 struct socket *ssock;
101 int err;
102
103 err = mptcp_subflow_create_socket(sk, &ssock);
104 if (err)
105 return err;
106
107 msk->first = ssock->sk;
108 msk->subflow = ssock;
109 subflow = mptcp_subflow_ctx(ssock->sk);
110 list_add(&subflow->node, &msk->conn_list);
111 sock_hold(ssock->sk);
112 subflow->request_mptcp = 1;
113 mptcp_sock_graft(msk->first, sk->sk_socket);
114
115 return 0;
116 }
117
mptcp_drop(struct sock * sk,struct sk_buff * skb)118 static void mptcp_drop(struct sock *sk, struct sk_buff *skb)
119 {
120 sk_drops_add(sk, skb);
121 __kfree_skb(skb);
122 }
123
mptcp_try_coalesce(struct sock * sk,struct sk_buff * to,struct sk_buff * from)124 static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to,
125 struct sk_buff *from)
126 {
127 bool fragstolen;
128 int delta;
129
130 if (MPTCP_SKB_CB(from)->offset ||
131 !skb_try_coalesce(to, from, &fragstolen, &delta))
132 return false;
133
134 pr_debug("colesced seq %llx into %llx new len %d new end seq %llx",
135 MPTCP_SKB_CB(from)->map_seq, MPTCP_SKB_CB(to)->map_seq,
136 to->len, MPTCP_SKB_CB(from)->end_seq);
137 MPTCP_SKB_CB(to)->end_seq = MPTCP_SKB_CB(from)->end_seq;
138 kfree_skb_partial(from, fragstolen);
139 atomic_add(delta, &sk->sk_rmem_alloc);
140 sk_mem_charge(sk, delta);
141 return true;
142 }
143
mptcp_ooo_try_coalesce(struct mptcp_sock * msk,struct sk_buff * to,struct sk_buff * from)144 static bool mptcp_ooo_try_coalesce(struct mptcp_sock *msk, struct sk_buff *to,
145 struct sk_buff *from)
146 {
147 if (MPTCP_SKB_CB(from)->map_seq != MPTCP_SKB_CB(to)->end_seq)
148 return false;
149
150 return mptcp_try_coalesce((struct sock *)msk, to, from);
151 }
152
153 /* "inspired" by tcp_data_queue_ofo(), main differences:
154 * - use mptcp seqs
155 * - don't cope with sacks
156 */
mptcp_data_queue_ofo(struct mptcp_sock * msk,struct sk_buff * skb)157 static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)
158 {
159 struct sock *sk = (struct sock *)msk;
160 struct rb_node **p, *parent;
161 u64 seq, end_seq, max_seq;
162 struct sk_buff *skb1;
163
164 seq = MPTCP_SKB_CB(skb)->map_seq;
165 end_seq = MPTCP_SKB_CB(skb)->end_seq;
166 max_seq = READ_ONCE(msk->rcv_wnd_sent);
167
168 pr_debug("msk=%p seq=%llx limit=%llx empty=%d", msk, seq, max_seq,
169 RB_EMPTY_ROOT(&msk->out_of_order_queue));
170 if (after64(end_seq, max_seq)) {
171 /* out of window */
172 mptcp_drop(sk, skb);
173 pr_debug("oow by %lld, rcv_wnd_sent %llu\n",
174 (unsigned long long)end_seq - (unsigned long)max_seq,
175 (unsigned long long)msk->rcv_wnd_sent);
176 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW);
177 return;
178 }
179
180 p = &msk->out_of_order_queue.rb_node;
181 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUE);
182 if (RB_EMPTY_ROOT(&msk->out_of_order_queue)) {
183 rb_link_node(&skb->rbnode, NULL, p);
184 rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
185 msk->ooo_last_skb = skb;
186 goto end;
187 }
188
189 /* with 2 subflows, adding at end of ooo queue is quite likely
190 * Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup.
191 */
192 if (mptcp_ooo_try_coalesce(msk, msk->ooo_last_skb, skb)) {
193 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE);
194 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL);
195 return;
196 }
197
198 /* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */
199 if (!before64(seq, MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq)) {
200 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL);
201 parent = &msk->ooo_last_skb->rbnode;
202 p = &parent->rb_right;
203 goto insert;
204 }
205
206 /* Find place to insert this segment. Handle overlaps on the way. */
207 parent = NULL;
208 while (*p) {
209 parent = *p;
210 skb1 = rb_to_skb(parent);
211 if (before64(seq, MPTCP_SKB_CB(skb1)->map_seq)) {
212 p = &parent->rb_left;
213 continue;
214 }
215 if (before64(seq, MPTCP_SKB_CB(skb1)->end_seq)) {
216 if (!after64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) {
217 /* All the bits are present. Drop. */
218 mptcp_drop(sk, skb);
219 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
220 return;
221 }
222 if (after64(seq, MPTCP_SKB_CB(skb1)->map_seq)) {
223 /* partial overlap:
224 * | skb |
225 * | skb1 |
226 * continue traversing
227 */
228 } else {
229 /* skb's seq == skb1's seq and skb covers skb1.
230 * Replace skb1 with skb.
231 */
232 rb_replace_node(&skb1->rbnode, &skb->rbnode,
233 &msk->out_of_order_queue);
234 mptcp_drop(sk, skb1);
235 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
236 goto merge_right;
237 }
238 } else if (mptcp_ooo_try_coalesce(msk, skb1, skb)) {
239 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE);
240 return;
241 }
242 p = &parent->rb_right;
243 }
244
245 insert:
246 /* Insert segment into RB tree. */
247 rb_link_node(&skb->rbnode, parent, p);
248 rb_insert_color(&skb->rbnode, &msk->out_of_order_queue);
249
250 merge_right:
251 /* Remove other segments covered by skb. */
252 while ((skb1 = skb_rb_next(skb)) != NULL) {
253 if (before64(end_seq, MPTCP_SKB_CB(skb1)->end_seq))
254 break;
255 rb_erase(&skb1->rbnode, &msk->out_of_order_queue);
256 mptcp_drop(sk, skb1);
257 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
258 }
259 /* If there is no skb after us, we are the last_skb ! */
260 if (!skb1)
261 msk->ooo_last_skb = skb;
262
263 end:
264 skb_condense(skb);
265 skb_set_owner_r(skb, sk);
266 }
267
__mptcp_move_skb(struct mptcp_sock * msk,struct sock * ssk,struct sk_buff * skb,unsigned int offset,size_t copy_len)268 static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
269 struct sk_buff *skb, unsigned int offset,
270 size_t copy_len)
271 {
272 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
273 struct sock *sk = (struct sock *)msk;
274 struct sk_buff *tail;
275
276 __skb_unlink(skb, &ssk->sk_receive_queue);
277
278 skb_ext_reset(skb);
279 skb_orphan(skb);
280
281 /* try to fetch required memory from subflow */
282 if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
283 if (ssk->sk_forward_alloc < skb->truesize)
284 goto drop;
285 __sk_mem_reclaim(ssk, skb->truesize);
286 if (!sk_rmem_schedule(sk, skb, skb->truesize))
287 goto drop;
288 }
289
290 /* the skb map_seq accounts for the skb offset:
291 * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq
292 * value
293 */
294 MPTCP_SKB_CB(skb)->map_seq = mptcp_subflow_get_mapped_dsn(subflow);
295 MPTCP_SKB_CB(skb)->end_seq = MPTCP_SKB_CB(skb)->map_seq + copy_len;
296 MPTCP_SKB_CB(skb)->offset = offset;
297
298 if (MPTCP_SKB_CB(skb)->map_seq == msk->ack_seq) {
299 /* in sequence */
300 WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
301 tail = skb_peek_tail(&sk->sk_receive_queue);
302 if (tail && mptcp_try_coalesce(sk, tail, skb))
303 return true;
304
305 skb_set_owner_r(skb, sk);
306 __skb_queue_tail(&sk->sk_receive_queue, skb);
307 return true;
308 } else if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) {
309 mptcp_data_queue_ofo(msk, skb);
310 return false;
311 }
312
313 /* old data, keep it simple and drop the whole pkt, sender
314 * will retransmit as needed, if needed.
315 */
316 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
317 drop:
318 mptcp_drop(sk, skb);
319 return false;
320 }
321
mptcp_stop_timer(struct sock * sk)322 static void mptcp_stop_timer(struct sock *sk)
323 {
324 struct inet_connection_sock *icsk = inet_csk(sk);
325
326 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
327 mptcp_sk(sk)->timer_ival = 0;
328 }
329
mptcp_close_wake_up(struct sock * sk)330 static void mptcp_close_wake_up(struct sock *sk)
331 {
332 if (sock_flag(sk, SOCK_DEAD))
333 return;
334
335 sk->sk_state_change(sk);
336 if (sk->sk_shutdown == SHUTDOWN_MASK ||
337 sk->sk_state == TCP_CLOSE)
338 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
339 else
340 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
341 }
342
mptcp_pending_data_fin_ack(struct sock * sk)343 static bool mptcp_pending_data_fin_ack(struct sock *sk)
344 {
345 struct mptcp_sock *msk = mptcp_sk(sk);
346
347 return !__mptcp_check_fallback(msk) &&
348 ((1 << sk->sk_state) &
349 (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) &&
350 msk->write_seq == READ_ONCE(msk->snd_una);
351 }
352
mptcp_check_data_fin_ack(struct sock * sk)353 static void mptcp_check_data_fin_ack(struct sock *sk)
354 {
355 struct mptcp_sock *msk = mptcp_sk(sk);
356
357 /* Look for an acknowledged DATA_FIN */
358 if (mptcp_pending_data_fin_ack(sk)) {
359 WRITE_ONCE(msk->snd_data_fin_enable, 0);
360
361 switch (sk->sk_state) {
362 case TCP_FIN_WAIT1:
363 inet_sk_state_store(sk, TCP_FIN_WAIT2);
364 break;
365 case TCP_CLOSING:
366 case TCP_LAST_ACK:
367 inet_sk_state_store(sk, TCP_CLOSE);
368 break;
369 }
370
371 mptcp_close_wake_up(sk);
372 }
373 }
374
mptcp_pending_data_fin(struct sock * sk,u64 * seq)375 static bool mptcp_pending_data_fin(struct sock *sk, u64 *seq)
376 {
377 struct mptcp_sock *msk = mptcp_sk(sk);
378
379 if (READ_ONCE(msk->rcv_data_fin) &&
380 ((1 << sk->sk_state) &
381 (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2))) {
382 u64 rcv_data_fin_seq = READ_ONCE(msk->rcv_data_fin_seq);
383
384 if (msk->ack_seq == rcv_data_fin_seq) {
385 if (seq)
386 *seq = rcv_data_fin_seq;
387
388 return true;
389 }
390 }
391
392 return false;
393 }
394
mptcp_set_datafin_timeout(const struct sock * sk)395 static void mptcp_set_datafin_timeout(const struct sock *sk)
396 {
397 struct inet_connection_sock *icsk = inet_csk(sk);
398
399 mptcp_sk(sk)->timer_ival = min(TCP_RTO_MAX,
400 TCP_RTO_MIN << icsk->icsk_retransmits);
401 }
402
mptcp_set_timeout(const struct sock * sk,const struct sock * ssk)403 static void mptcp_set_timeout(const struct sock *sk, const struct sock *ssk)
404 {
405 long tout = ssk && inet_csk(ssk)->icsk_pending ?
406 inet_csk(ssk)->icsk_timeout - jiffies : 0;
407
408 if (tout <= 0)
409 tout = mptcp_sk(sk)->timer_ival;
410 mptcp_sk(sk)->timer_ival = tout > 0 ? tout : TCP_RTO_MIN;
411 }
412
tcp_can_send_ack(const struct sock * ssk)413 static bool tcp_can_send_ack(const struct sock *ssk)
414 {
415 return !((1 << inet_sk_state_load(ssk)) &
416 (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE | TCPF_LISTEN));
417 }
418
mptcp_send_ack(struct mptcp_sock * msk)419 static void mptcp_send_ack(struct mptcp_sock *msk)
420 {
421 struct mptcp_subflow_context *subflow;
422
423 mptcp_for_each_subflow(msk, subflow) {
424 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
425
426 lock_sock(ssk);
427 if (tcp_can_send_ack(ssk))
428 tcp_send_ack(ssk);
429 release_sock(ssk);
430 }
431 }
432
mptcp_subflow_cleanup_rbuf(struct sock * ssk)433 static bool mptcp_subflow_cleanup_rbuf(struct sock *ssk)
434 {
435 int ret;
436
437 lock_sock(ssk);
438 ret = tcp_can_send_ack(ssk);
439 if (ret)
440 tcp_cleanup_rbuf(ssk, 1);
441 release_sock(ssk);
442 return ret;
443 }
444
mptcp_cleanup_rbuf(struct mptcp_sock * msk)445 static void mptcp_cleanup_rbuf(struct mptcp_sock *msk)
446 {
447 struct sock *ack_hint = READ_ONCE(msk->ack_hint);
448 int old_space = READ_ONCE(msk->old_wspace);
449 struct mptcp_subflow_context *subflow;
450 struct sock *sk = (struct sock *)msk;
451 bool cleanup;
452
453 /* this is a simple superset of what tcp_cleanup_rbuf() implements
454 * so that we don't have to acquire the ssk socket lock most of the time
455 * to do actually nothing
456 */
457 cleanup = __mptcp_space(sk) - old_space >= max(0, old_space);
458 if (!cleanup)
459 return;
460
461 /* if the hinted ssk is still active, try to use it */
462 if (likely(ack_hint)) {
463 mptcp_for_each_subflow(msk, subflow) {
464 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
465
466 if (ack_hint == ssk && mptcp_subflow_cleanup_rbuf(ssk))
467 return;
468 }
469 }
470
471 /* otherwise pick the first active subflow */
472 mptcp_for_each_subflow(msk, subflow)
473 if (mptcp_subflow_cleanup_rbuf(mptcp_subflow_tcp_sock(subflow)))
474 return;
475 }
476
mptcp_check_data_fin(struct sock * sk)477 static bool mptcp_check_data_fin(struct sock *sk)
478 {
479 struct mptcp_sock *msk = mptcp_sk(sk);
480 u64 rcv_data_fin_seq;
481 bool ret = false;
482
483 if (__mptcp_check_fallback(msk))
484 return ret;
485
486 /* Need to ack a DATA_FIN received from a peer while this side
487 * of the connection is in ESTABLISHED, FIN_WAIT1, or FIN_WAIT2.
488 * msk->rcv_data_fin was set when parsing the incoming options
489 * at the subflow level and the msk lock was not held, so this
490 * is the first opportunity to act on the DATA_FIN and change
491 * the msk state.
492 *
493 * If we are caught up to the sequence number of the incoming
494 * DATA_FIN, send the DATA_ACK now and do state transition. If
495 * not caught up, do nothing and let the recv code send DATA_ACK
496 * when catching up.
497 */
498
499 if (mptcp_pending_data_fin(sk, &rcv_data_fin_seq)) {
500 WRITE_ONCE(msk->ack_seq, msk->ack_seq + 1);
501 WRITE_ONCE(msk->rcv_data_fin, 0);
502
503 sk->sk_shutdown |= RCV_SHUTDOWN;
504 smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
505 set_bit(MPTCP_DATA_READY, &msk->flags);
506
507 switch (sk->sk_state) {
508 case TCP_ESTABLISHED:
509 inet_sk_state_store(sk, TCP_CLOSE_WAIT);
510 break;
511 case TCP_FIN_WAIT1:
512 inet_sk_state_store(sk, TCP_CLOSING);
513 break;
514 case TCP_FIN_WAIT2:
515 inet_sk_state_store(sk, TCP_CLOSE);
516 break;
517 default:
518 /* Other states not expected */
519 WARN_ON_ONCE(1);
520 break;
521 }
522
523 ret = true;
524 mptcp_set_timeout(sk, NULL);
525 mptcp_send_ack(msk);
526 mptcp_close_wake_up(sk);
527 }
528 return ret;
529 }
530
__mptcp_move_skbs_from_subflow(struct mptcp_sock * msk,struct sock * ssk,unsigned int * bytes)531 static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
532 struct sock *ssk,
533 unsigned int *bytes)
534 {
535 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
536 struct sock *sk = (struct sock *)msk;
537 unsigned int moved = 0;
538 bool more_data_avail;
539 struct tcp_sock *tp;
540 bool done = false;
541 int sk_rbuf;
542
543 sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
544
545 if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
546 int ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
547
548 if (unlikely(ssk_rbuf > sk_rbuf)) {
549 WRITE_ONCE(sk->sk_rcvbuf, ssk_rbuf);
550 sk_rbuf = ssk_rbuf;
551 }
552 }
553
554 pr_debug("msk=%p ssk=%p", msk, ssk);
555 tp = tcp_sk(ssk);
556 do {
557 u32 map_remaining, offset;
558 u32 seq = tp->copied_seq;
559 struct sk_buff *skb;
560 bool fin;
561
562 /* try to move as much data as available */
563 map_remaining = subflow->map_data_len -
564 mptcp_subflow_get_map_offset(subflow);
565
566 skb = skb_peek(&ssk->sk_receive_queue);
567 if (!skb) {
568 /* if no data is found, a racing workqueue/recvmsg
569 * already processed the new data, stop here or we
570 * can enter an infinite loop
571 */
572 if (!moved)
573 done = true;
574 break;
575 }
576
577 if (__mptcp_check_fallback(msk)) {
578 /* if we are running under the workqueue, TCP could have
579 * collapsed skbs between dummy map creation and now
580 * be sure to adjust the size
581 */
582 map_remaining = skb->len;
583 subflow->map_data_len = skb->len;
584 }
585
586 offset = seq - TCP_SKB_CB(skb)->seq;
587 fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
588 if (fin) {
589 done = true;
590 seq++;
591 }
592
593 if (offset < skb->len) {
594 size_t len = skb->len - offset;
595
596 if (tp->urg_data)
597 done = true;
598
599 if (__mptcp_move_skb(msk, ssk, skb, offset, len))
600 moved += len;
601 seq += len;
602
603 if (WARN_ON_ONCE(map_remaining < len))
604 break;
605 } else {
606 WARN_ON_ONCE(!fin);
607 sk_eat_skb(ssk, skb);
608 done = true;
609 }
610
611 WRITE_ONCE(tp->copied_seq, seq);
612 more_data_avail = mptcp_subflow_data_available(ssk);
613
614 if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf) {
615 done = true;
616 break;
617 }
618 } while (more_data_avail);
619 WRITE_ONCE(msk->ack_hint, ssk);
620
621 *bytes += moved;
622 return done;
623 }
624
__mptcp_ofo_queue(struct mptcp_sock * msk)625 static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
626 {
627 struct sock *sk = (struct sock *)msk;
628 struct sk_buff *skb, *tail;
629 bool moved = false;
630 struct rb_node *p;
631 u64 end_seq;
632
633 p = rb_first(&msk->out_of_order_queue);
634 pr_debug("msk=%p empty=%d", msk, RB_EMPTY_ROOT(&msk->out_of_order_queue));
635 while (p) {
636 skb = rb_to_skb(p);
637 if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq))
638 break;
639
640 p = rb_next(p);
641 rb_erase(&skb->rbnode, &msk->out_of_order_queue);
642
643 if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq,
644 msk->ack_seq))) {
645 mptcp_drop(sk, skb);
646 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
647 continue;
648 }
649
650 end_seq = MPTCP_SKB_CB(skb)->end_seq;
651 tail = skb_peek_tail(&sk->sk_receive_queue);
652 if (!tail || !mptcp_ooo_try_coalesce(msk, tail, skb)) {
653 int delta = msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq;
654
655 /* skip overlapping data, if any */
656 pr_debug("uncoalesced seq=%llx ack seq=%llx delta=%d",
657 MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq,
658 delta);
659 MPTCP_SKB_CB(skb)->offset += delta;
660 __skb_queue_tail(&sk->sk_receive_queue, skb);
661 }
662 msk->ack_seq = end_seq;
663 moved = true;
664 }
665 return moved;
666 }
667
668 /* In most cases we will be able to lock the mptcp socket. If its already
669 * owned, we need to defer to the work queue to avoid ABBA deadlock.
670 */
move_skbs_to_msk(struct mptcp_sock * msk,struct sock * ssk)671 static void move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
672 {
673 struct sock *sk = (struct sock *)msk;
674 unsigned int moved = 0;
675
676 if (inet_sk_state_load(sk) == TCP_CLOSE)
677 return;
678
679 mptcp_data_lock(sk);
680
681 __mptcp_move_skbs_from_subflow(msk, ssk, &moved);
682 __mptcp_ofo_queue(msk);
683
684 /* If the moves have caught up with the DATA_FIN sequence number
685 * it's time to ack the DATA_FIN and change socket state, but
686 * this is not a good place to change state. Let the workqueue
687 * do it.
688 */
689 if (mptcp_pending_data_fin(sk, NULL))
690 mptcp_schedule_work(sk);
691 mptcp_data_unlock(sk);
692 }
693
mptcp_data_ready(struct sock * sk,struct sock * ssk)694 void mptcp_data_ready(struct sock *sk, struct sock *ssk)
695 {
696 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
697 struct mptcp_sock *msk = mptcp_sk(sk);
698 int sk_rbuf, ssk_rbuf;
699 bool wake;
700
701 /* The peer can send data while we are shutting down this
702 * subflow at msk destruction time, but we must avoid enqueuing
703 * more data to the msk receive queue
704 */
705 if (unlikely(subflow->disposable))
706 return;
707
708 /* move_skbs_to_msk below can legitly clear the data_avail flag,
709 * but we will need later to properly woke the reader, cache its
710 * value
711 */
712 wake = subflow->data_avail == MPTCP_SUBFLOW_DATA_AVAIL;
713 if (wake)
714 set_bit(MPTCP_DATA_READY, &msk->flags);
715
716 ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
717 sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
718 if (unlikely(ssk_rbuf > sk_rbuf))
719 sk_rbuf = ssk_rbuf;
720
721 /* over limit? can't append more skbs to msk */
722 if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf)
723 goto wake;
724
725 move_skbs_to_msk(msk, ssk);
726
727 wake:
728 if (wake)
729 sk->sk_data_ready(sk);
730 }
731
mptcp_do_flush_join_list(struct mptcp_sock * msk)732 static bool mptcp_do_flush_join_list(struct mptcp_sock *msk)
733 {
734 struct mptcp_subflow_context *subflow;
735 bool ret = false;
736
737 if (likely(list_empty(&msk->join_list)))
738 return false;
739
740 spin_lock_bh(&msk->join_list_lock);
741 list_for_each_entry(subflow, &msk->join_list, node) {
742 u32 sseq = READ_ONCE(subflow->setsockopt_seq);
743
744 mptcp_propagate_sndbuf((struct sock *)msk, mptcp_subflow_tcp_sock(subflow));
745 if (READ_ONCE(msk->setsockopt_seq) != sseq)
746 ret = true;
747 }
748 list_splice_tail_init(&msk->join_list, &msk->conn_list);
749 spin_unlock_bh(&msk->join_list_lock);
750
751 return ret;
752 }
753
__mptcp_flush_join_list(struct mptcp_sock * msk)754 void __mptcp_flush_join_list(struct mptcp_sock *msk)
755 {
756 if (likely(!mptcp_do_flush_join_list(msk)))
757 return;
758
759 if (!test_and_set_bit(MPTCP_WORK_SYNC_SETSOCKOPT, &msk->flags))
760 mptcp_schedule_work((struct sock *)msk);
761 }
762
mptcp_flush_join_list(struct mptcp_sock * msk)763 static void mptcp_flush_join_list(struct mptcp_sock *msk)
764 {
765 bool sync_needed = test_and_clear_bit(MPTCP_WORK_SYNC_SETSOCKOPT, &msk->flags);
766
767 might_sleep();
768
769 if (!mptcp_do_flush_join_list(msk) && !sync_needed)
770 return;
771
772 mptcp_sockopt_sync_all(msk);
773 }
774
mptcp_timer_pending(struct sock * sk)775 static bool mptcp_timer_pending(struct sock *sk)
776 {
777 return timer_pending(&inet_csk(sk)->icsk_retransmit_timer);
778 }
779
mptcp_reset_timer(struct sock * sk)780 static void mptcp_reset_timer(struct sock *sk)
781 {
782 struct inet_connection_sock *icsk = inet_csk(sk);
783 unsigned long tout;
784
785 /* prevent rescheduling on close */
786 if (unlikely(inet_sk_state_load(sk) == TCP_CLOSE))
787 return;
788
789 /* should never be called with mptcp level timer cleared */
790 tout = READ_ONCE(mptcp_sk(sk)->timer_ival);
791 if (WARN_ON_ONCE(!tout))
792 tout = TCP_RTO_MIN;
793 sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout);
794 }
795
mptcp_schedule_work(struct sock * sk)796 bool mptcp_schedule_work(struct sock *sk)
797 {
798 if (inet_sk_state_load(sk) != TCP_CLOSE &&
799 schedule_work(&mptcp_sk(sk)->work)) {
800 /* each subflow already holds a reference to the sk, and the
801 * workqueue is invoked by a subflow, so sk can't go away here.
802 */
803 sock_hold(sk);
804 return true;
805 }
806 return false;
807 }
808
mptcp_subflow_eof(struct sock * sk)809 void mptcp_subflow_eof(struct sock *sk)
810 {
811 if (!test_and_set_bit(MPTCP_WORK_EOF, &mptcp_sk(sk)->flags))
812 mptcp_schedule_work(sk);
813 }
814
mptcp_check_for_eof(struct mptcp_sock * msk)815 static void mptcp_check_for_eof(struct mptcp_sock *msk)
816 {
817 struct mptcp_subflow_context *subflow;
818 struct sock *sk = (struct sock *)msk;
819 int receivers = 0;
820
821 mptcp_for_each_subflow(msk, subflow)
822 receivers += !subflow->rx_eof;
823 if (receivers)
824 return;
825
826 if (!(sk->sk_shutdown & RCV_SHUTDOWN)) {
827 /* hopefully temporary hack: propagate shutdown status
828 * to msk, when all subflows agree on it
829 */
830 sk->sk_shutdown |= RCV_SHUTDOWN;
831
832 smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
833 set_bit(MPTCP_DATA_READY, &msk->flags);
834 sk->sk_data_ready(sk);
835 }
836
837 switch (sk->sk_state) {
838 case TCP_ESTABLISHED:
839 inet_sk_state_store(sk, TCP_CLOSE_WAIT);
840 break;
841 case TCP_FIN_WAIT1:
842 inet_sk_state_store(sk, TCP_CLOSING);
843 break;
844 case TCP_FIN_WAIT2:
845 inet_sk_state_store(sk, TCP_CLOSE);
846 break;
847 default:
848 return;
849 }
850 mptcp_close_wake_up(sk);
851 }
852
mptcp_subflow_recv_lookup(const struct mptcp_sock * msk)853 static struct sock *mptcp_subflow_recv_lookup(const struct mptcp_sock *msk)
854 {
855 struct mptcp_subflow_context *subflow;
856 struct sock *sk = (struct sock *)msk;
857
858 sock_owned_by_me(sk);
859
860 mptcp_for_each_subflow(msk, subflow) {
861 if (subflow->data_avail)
862 return mptcp_subflow_tcp_sock(subflow);
863 }
864
865 return NULL;
866 }
867
mptcp_skb_can_collapse_to(u64 write_seq,const struct sk_buff * skb,const struct mptcp_ext * mpext)868 static bool mptcp_skb_can_collapse_to(u64 write_seq,
869 const struct sk_buff *skb,
870 const struct mptcp_ext *mpext)
871 {
872 if (!tcp_skb_can_collapse_to(skb))
873 return false;
874
875 /* can collapse only if MPTCP level sequence is in order and this
876 * mapping has not been xmitted yet
877 */
878 return mpext && mpext->data_seq + mpext->data_len == write_seq &&
879 !mpext->frozen;
880 }
881
mptcp_frag_can_collapse_to(const struct mptcp_sock * msk,const struct page_frag * pfrag,const struct mptcp_data_frag * df)882 static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
883 const struct page_frag *pfrag,
884 const struct mptcp_data_frag *df)
885 {
886 return df && pfrag->page == df->page &&
887 pfrag->size - pfrag->offset > 0 &&
888 df->data_seq + df->data_len == msk->write_seq;
889 }
890
mptcp_wmem_with_overhead(struct sock * sk,int size)891 static int mptcp_wmem_with_overhead(struct sock *sk, int size)
892 {
893 struct mptcp_sock *msk = mptcp_sk(sk);
894 int ret, skbs;
895
896 ret = size + ((sizeof(struct mptcp_data_frag) * size) >> PAGE_SHIFT);
897 skbs = (msk->tx_pending_data + size) / msk->size_goal_cache;
898 if (skbs < msk->skb_tx_cache.qlen)
899 return ret;
900
901 return ret + (skbs - msk->skb_tx_cache.qlen) * SKB_TRUESIZE(MAX_TCP_HEADER);
902 }
903
__mptcp_wmem_reserve(struct sock * sk,int size)904 static void __mptcp_wmem_reserve(struct sock *sk, int size)
905 {
906 int amount = mptcp_wmem_with_overhead(sk, size);
907 struct mptcp_sock *msk = mptcp_sk(sk);
908
909 WARN_ON_ONCE(msk->wmem_reserved);
910 if (WARN_ON_ONCE(amount < 0))
911 amount = 0;
912
913 if (amount <= sk->sk_forward_alloc)
914 goto reserve;
915
916 /* under memory pressure try to reserve at most a single page
917 * otherwise try to reserve the full estimate and fallback
918 * to a single page before entering the error path
919 */
920 if ((tcp_under_memory_pressure(sk) && amount > PAGE_SIZE) ||
921 !sk_wmem_schedule(sk, amount)) {
922 if (amount <= PAGE_SIZE)
923 goto nomem;
924
925 amount = PAGE_SIZE;
926 if (!sk_wmem_schedule(sk, amount))
927 goto nomem;
928 }
929
930 reserve:
931 msk->wmem_reserved = amount;
932 sk->sk_forward_alloc -= amount;
933 return;
934
935 nomem:
936 /* we will wait for memory on next allocation */
937 msk->wmem_reserved = -1;
938 }
939
__mptcp_update_wmem(struct sock * sk)940 static void __mptcp_update_wmem(struct sock *sk)
941 {
942 struct mptcp_sock *msk = mptcp_sk(sk);
943
944 if (!msk->wmem_reserved)
945 return;
946
947 if (msk->wmem_reserved < 0)
948 msk->wmem_reserved = 0;
949 if (msk->wmem_reserved > 0) {
950 sk->sk_forward_alloc += msk->wmem_reserved;
951 msk->wmem_reserved = 0;
952 }
953 }
954
mptcp_wmem_alloc(struct sock * sk,int size)955 static bool mptcp_wmem_alloc(struct sock *sk, int size)
956 {
957 struct mptcp_sock *msk = mptcp_sk(sk);
958
959 /* check for pre-existing error condition */
960 if (msk->wmem_reserved < 0)
961 return false;
962
963 if (msk->wmem_reserved >= size)
964 goto account;
965
966 mptcp_data_lock(sk);
967 if (!sk_wmem_schedule(sk, size)) {
968 mptcp_data_unlock(sk);
969 return false;
970 }
971
972 sk->sk_forward_alloc -= size;
973 msk->wmem_reserved += size;
974 mptcp_data_unlock(sk);
975
976 account:
977 msk->wmem_reserved -= size;
978 return true;
979 }
980
mptcp_wmem_uncharge(struct sock * sk,int size)981 static void mptcp_wmem_uncharge(struct sock *sk, int size)
982 {
983 struct mptcp_sock *msk = mptcp_sk(sk);
984
985 if (msk->wmem_reserved < 0)
986 msk->wmem_reserved = 0;
987 msk->wmem_reserved += size;
988 }
989
mptcp_mem_reclaim_partial(struct sock * sk)990 static void mptcp_mem_reclaim_partial(struct sock *sk)
991 {
992 struct mptcp_sock *msk = mptcp_sk(sk);
993
994 /* if we are experiencing a transint allocation error,
995 * the forward allocation memory has been already
996 * released
997 */
998 if (msk->wmem_reserved < 0)
999 return;
1000
1001 mptcp_data_lock(sk);
1002 sk->sk_forward_alloc += msk->wmem_reserved;
1003 sk_mem_reclaim_partial(sk);
1004 msk->wmem_reserved = sk->sk_forward_alloc;
1005 sk->sk_forward_alloc = 0;
1006 mptcp_data_unlock(sk);
1007 }
1008
dfrag_uncharge(struct sock * sk,int len)1009 static void dfrag_uncharge(struct sock *sk, int len)
1010 {
1011 sk_mem_uncharge(sk, len);
1012 sk_wmem_queued_add(sk, -len);
1013 }
1014
dfrag_clear(struct sock * sk,struct mptcp_data_frag * dfrag)1015 static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
1016 {
1017 int len = dfrag->data_len + dfrag->overhead;
1018
1019 list_del(&dfrag->list);
1020 dfrag_uncharge(sk, len);
1021 put_page(dfrag->page);
1022 }
1023
__mptcp_clean_una(struct sock * sk)1024 static void __mptcp_clean_una(struct sock *sk)
1025 {
1026 struct mptcp_sock *msk = mptcp_sk(sk);
1027 struct mptcp_data_frag *dtmp, *dfrag;
1028 bool cleaned = false;
1029 u64 snd_una;
1030
1031 /* on fallback we just need to ignore snd_una, as this is really
1032 * plain TCP
1033 */
1034 if (__mptcp_check_fallback(msk))
1035 msk->snd_una = READ_ONCE(msk->snd_nxt);
1036
1037 snd_una = msk->snd_una;
1038 list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
1039 if (after64(dfrag->data_seq + dfrag->data_len, snd_una))
1040 break;
1041
1042 if (WARN_ON_ONCE(dfrag == msk->first_pending))
1043 break;
1044 dfrag_clear(sk, dfrag);
1045 cleaned = true;
1046 }
1047
1048 dfrag = mptcp_rtx_head(sk);
1049 if (dfrag && after64(snd_una, dfrag->data_seq)) {
1050 u64 delta = snd_una - dfrag->data_seq;
1051
1052 if (WARN_ON_ONCE(delta > dfrag->already_sent))
1053 goto out;
1054
1055 dfrag->data_seq += delta;
1056 dfrag->offset += delta;
1057 dfrag->data_len -= delta;
1058 dfrag->already_sent -= delta;
1059
1060 dfrag_uncharge(sk, delta);
1061 cleaned = true;
1062 }
1063
1064 out:
1065 if (cleaned) {
1066 if (tcp_under_memory_pressure(sk)) {
1067 __mptcp_update_wmem(sk);
1068 sk_mem_reclaim_partial(sk);
1069 }
1070 }
1071
1072 if (snd_una == READ_ONCE(msk->snd_nxt)) {
1073 if (msk->timer_ival && !mptcp_data_fin_enabled(msk))
1074 mptcp_stop_timer(sk);
1075 } else {
1076 mptcp_reset_timer(sk);
1077 }
1078 }
1079
__mptcp_clean_una_wakeup(struct sock * sk)1080 static void __mptcp_clean_una_wakeup(struct sock *sk)
1081 {
1082 __mptcp_clean_una(sk);
1083 mptcp_write_space(sk);
1084 }
1085
mptcp_enter_memory_pressure(struct sock * sk)1086 static void mptcp_enter_memory_pressure(struct sock *sk)
1087 {
1088 struct mptcp_subflow_context *subflow;
1089 struct mptcp_sock *msk = mptcp_sk(sk);
1090 bool first = true;
1091
1092 sk_stream_moderate_sndbuf(sk);
1093 mptcp_for_each_subflow(msk, subflow) {
1094 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1095
1096 if (first)
1097 tcp_enter_memory_pressure(ssk);
1098 sk_stream_moderate_sndbuf(ssk);
1099 first = false;
1100 }
1101 }
1102
1103 /* ensure we get enough memory for the frag hdr, beyond some minimal amount of
1104 * data
1105 */
mptcp_page_frag_refill(struct sock * sk,struct page_frag * pfrag)1106 static bool mptcp_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
1107 {
1108 if (likely(skb_page_frag_refill(32U + sizeof(struct mptcp_data_frag),
1109 pfrag, sk->sk_allocation)))
1110 return true;
1111
1112 mptcp_enter_memory_pressure(sk);
1113 return false;
1114 }
1115
1116 static struct mptcp_data_frag *
mptcp_carve_data_frag(const struct mptcp_sock * msk,struct page_frag * pfrag,int orig_offset)1117 mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag,
1118 int orig_offset)
1119 {
1120 int offset = ALIGN(orig_offset, sizeof(long));
1121 struct mptcp_data_frag *dfrag;
1122
1123 dfrag = (struct mptcp_data_frag *)(page_to_virt(pfrag->page) + offset);
1124 dfrag->data_len = 0;
1125 dfrag->data_seq = msk->write_seq;
1126 dfrag->overhead = offset - orig_offset + sizeof(struct mptcp_data_frag);
1127 dfrag->offset = offset + sizeof(struct mptcp_data_frag);
1128 dfrag->already_sent = 0;
1129 dfrag->page = pfrag->page;
1130
1131 return dfrag;
1132 }
1133
1134 struct mptcp_sendmsg_info {
1135 int mss_now;
1136 int size_goal;
1137 u16 limit;
1138 u16 sent;
1139 unsigned int flags;
1140 };
1141
mptcp_check_allowed_size(struct mptcp_sock * msk,u64 data_seq,int avail_size)1142 static int mptcp_check_allowed_size(struct mptcp_sock *msk, u64 data_seq,
1143 int avail_size)
1144 {
1145 u64 window_end = mptcp_wnd_end(msk);
1146
1147 if (__mptcp_check_fallback(msk))
1148 return avail_size;
1149
1150 if (!before64(data_seq + avail_size, window_end)) {
1151 u64 allowed_size = window_end - data_seq;
1152
1153 return min_t(unsigned int, allowed_size, avail_size);
1154 }
1155
1156 return avail_size;
1157 }
1158
__mptcp_add_ext(struct sk_buff * skb,gfp_t gfp)1159 static bool __mptcp_add_ext(struct sk_buff *skb, gfp_t gfp)
1160 {
1161 struct skb_ext *mpext = __skb_ext_alloc(gfp);
1162
1163 if (!mpext)
1164 return false;
1165 __skb_ext_set(skb, SKB_EXT_MPTCP, mpext);
1166 return true;
1167 }
1168
__mptcp_do_alloc_tx_skb(struct sock * sk,gfp_t gfp)1169 static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
1170 {
1171 struct sk_buff *skb;
1172
1173 skb = alloc_skb_fclone(MAX_TCP_HEADER, gfp);
1174 if (likely(skb)) {
1175 if (likely(__mptcp_add_ext(skb, gfp))) {
1176 skb_reserve(skb, MAX_TCP_HEADER);
1177 skb->reserved_tailroom = skb->end - skb->tail;
1178 return skb;
1179 }
1180 __kfree_skb(skb);
1181 } else {
1182 mptcp_enter_memory_pressure(sk);
1183 }
1184 return NULL;
1185 }
1186
mptcp_tx_cache_refill(struct sock * sk,int size,struct sk_buff_head * skbs,int * total_ts)1187 static bool mptcp_tx_cache_refill(struct sock *sk, int size,
1188 struct sk_buff_head *skbs, int *total_ts)
1189 {
1190 struct mptcp_sock *msk = mptcp_sk(sk);
1191 struct sk_buff *skb;
1192 int space_needed;
1193
1194 if (unlikely(tcp_under_memory_pressure(sk))) {
1195 mptcp_mem_reclaim_partial(sk);
1196
1197 /* under pressure pre-allocate at most a single skb */
1198 if (msk->skb_tx_cache.qlen)
1199 return true;
1200 space_needed = msk->size_goal_cache;
1201 } else {
1202 space_needed = msk->tx_pending_data + size -
1203 msk->skb_tx_cache.qlen * msk->size_goal_cache;
1204 }
1205
1206 while (space_needed > 0) {
1207 skb = __mptcp_do_alloc_tx_skb(sk, sk->sk_allocation);
1208 if (unlikely(!skb)) {
1209 /* under memory pressure, try to pass the caller a
1210 * single skb to allow forward progress
1211 */
1212 while (skbs->qlen > 1) {
1213 skb = __skb_dequeue_tail(skbs);
1214 *total_ts -= skb->truesize;
1215 __kfree_skb(skb);
1216 }
1217 return skbs->qlen > 0;
1218 }
1219
1220 *total_ts += skb->truesize;
1221 __skb_queue_tail(skbs, skb);
1222 space_needed -= msk->size_goal_cache;
1223 }
1224 return true;
1225 }
1226
__mptcp_alloc_tx_skb(struct sock * sk,struct sock * ssk,gfp_t gfp)1227 static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
1228 {
1229 struct mptcp_sock *msk = mptcp_sk(sk);
1230 struct sk_buff *skb;
1231
1232 if (ssk->sk_tx_skb_cache) {
1233 skb = ssk->sk_tx_skb_cache;
1234 if (unlikely(!skb_ext_find(skb, SKB_EXT_MPTCP) &&
1235 !__mptcp_add_ext(skb, gfp)))
1236 return false;
1237 return true;
1238 }
1239
1240 skb = skb_peek(&msk->skb_tx_cache);
1241 if (skb) {
1242 if (likely(sk_wmem_schedule(ssk, skb->truesize))) {
1243 skb = __skb_dequeue(&msk->skb_tx_cache);
1244 if (WARN_ON_ONCE(!skb))
1245 return false;
1246
1247 mptcp_wmem_uncharge(sk, skb->truesize);
1248 ssk->sk_tx_skb_cache = skb;
1249 return true;
1250 }
1251
1252 /* over memory limit, no point to try to allocate a new skb */
1253 return false;
1254 }
1255
1256 skb = __mptcp_do_alloc_tx_skb(sk, gfp);
1257 if (!skb)
1258 return false;
1259
1260 if (likely(sk_wmem_schedule(ssk, skb->truesize))) {
1261 ssk->sk_tx_skb_cache = skb;
1262 return true;
1263 }
1264 kfree_skb(skb);
1265 return false;
1266 }
1267
mptcp_must_reclaim_memory(struct sock * sk,struct sock * ssk)1268 static bool mptcp_must_reclaim_memory(struct sock *sk, struct sock *ssk)
1269 {
1270 return !ssk->sk_tx_skb_cache &&
1271 !skb_peek(&mptcp_sk(sk)->skb_tx_cache) &&
1272 tcp_under_memory_pressure(sk);
1273 }
1274
mptcp_alloc_tx_skb(struct sock * sk,struct sock * ssk)1275 static bool mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk)
1276 {
1277 if (unlikely(mptcp_must_reclaim_memory(sk, ssk)))
1278 mptcp_mem_reclaim_partial(sk);
1279 return __mptcp_alloc_tx_skb(sk, ssk, sk->sk_allocation);
1280 }
1281
mptcp_sendmsg_frag(struct sock * sk,struct sock * ssk,struct mptcp_data_frag * dfrag,struct mptcp_sendmsg_info * info)1282 static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
1283 struct mptcp_data_frag *dfrag,
1284 struct mptcp_sendmsg_info *info)
1285 {
1286 u64 data_seq = dfrag->data_seq + info->sent;
1287 struct mptcp_sock *msk = mptcp_sk(sk);
1288 bool zero_window_probe = false;
1289 struct mptcp_ext *mpext = NULL;
1290 struct sk_buff *skb, *tail;
1291 bool can_collapse = false;
1292 int size_bias = 0;
1293 int avail_size;
1294 size_t ret = 0;
1295
1296 pr_debug("msk=%p ssk=%p sending dfrag at seq=%llu len=%u already sent=%u",
1297 msk, ssk, dfrag->data_seq, dfrag->data_len, info->sent);
1298
1299 /* compute send limit */
1300 info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags);
1301 avail_size = info->size_goal;
1302 msk->size_goal_cache = info->size_goal;
1303 skb = tcp_write_queue_tail(ssk);
1304 if (skb) {
1305 /* Limit the write to the size available in the
1306 * current skb, if any, so that we create at most a new skb.
1307 * Explicitly tells TCP internals to avoid collapsing on later
1308 * queue management operation, to avoid breaking the ext <->
1309 * SSN association set here
1310 */
1311 mpext = skb_ext_find(skb, SKB_EXT_MPTCP);
1312 can_collapse = (info->size_goal - skb->len > 0) &&
1313 mptcp_skb_can_collapse_to(data_seq, skb, mpext);
1314 if (!can_collapse) {
1315 TCP_SKB_CB(skb)->eor = 1;
1316 } else {
1317 size_bias = skb->len;
1318 avail_size = info->size_goal - skb->len;
1319 }
1320 }
1321
1322 /* Zero window and all data acked? Probe. */
1323 avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size);
1324 if (avail_size == 0) {
1325 u64 snd_una = READ_ONCE(msk->snd_una);
1326
1327 if (skb || snd_una != msk->snd_nxt)
1328 return 0;
1329 zero_window_probe = true;
1330 data_seq = snd_una - 1;
1331 avail_size = 1;
1332 }
1333
1334 if (WARN_ON_ONCE(info->sent > info->limit ||
1335 info->limit > dfrag->data_len))
1336 return 0;
1337
1338 ret = info->limit - info->sent;
1339 tail = tcp_build_frag(ssk, avail_size + size_bias, info->flags,
1340 dfrag->page, dfrag->offset + info->sent, &ret);
1341 if (!tail) {
1342 tcp_remove_empty_skb(sk, tcp_write_queue_tail(ssk));
1343 return -ENOMEM;
1344 }
1345
1346 /* if the tail skb is still the cached one, collapsing really happened.
1347 */
1348 if (skb == tail) {
1349 TCP_SKB_CB(tail)->tcp_flags &= ~TCPHDR_PSH;
1350 mpext->data_len += ret;
1351 WARN_ON_ONCE(!can_collapse);
1352 WARN_ON_ONCE(zero_window_probe);
1353 goto out;
1354 }
1355
1356 mpext = skb_ext_find(tail, SKB_EXT_MPTCP);
1357 if (WARN_ON_ONCE(!mpext)) {
1358 /* should never reach here, stream corrupted */
1359 return -EINVAL;
1360 }
1361
1362 memset(mpext, 0, sizeof(*mpext));
1363 mpext->data_seq = data_seq;
1364 mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq;
1365 mpext->data_len = ret;
1366 mpext->use_map = 1;
1367 mpext->dsn64 = 1;
1368
1369 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u dsn64=%d",
1370 mpext->data_seq, mpext->subflow_seq, mpext->data_len,
1371 mpext->dsn64);
1372
1373 if (zero_window_probe) {
1374 mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
1375 mpext->frozen = 1;
1376 ret = 0;
1377 tcp_push_pending_frames(ssk);
1378 }
1379 out:
1380 mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
1381 return ret;
1382 }
1383
1384 #define MPTCP_SEND_BURST_SIZE ((1 << 16) - \
1385 sizeof(struct tcphdr) - \
1386 MAX_TCP_OPTION_SPACE - \
1387 sizeof(struct ipv6hdr) - \
1388 sizeof(struct frag_hdr))
1389
1390 struct subflow_send_info {
1391 struct sock *ssk;
1392 u64 ratio;
1393 };
1394
mptcp_subflow_get_send(struct mptcp_sock * msk)1395 static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
1396 {
1397 struct subflow_send_info send_info[2];
1398 struct mptcp_subflow_context *subflow;
1399 int i, nr_active = 0;
1400 struct sock *ssk;
1401 u64 ratio;
1402 u32 pace;
1403
1404 sock_owned_by_me((struct sock *)msk);
1405
1406 if (__mptcp_check_fallback(msk)) {
1407 if (!msk->first)
1408 return NULL;
1409 return sk_stream_memory_free(msk->first) ? msk->first : NULL;
1410 }
1411
1412 /* re-use last subflow, if the burst allow that */
1413 if (msk->last_snd && msk->snd_burst > 0 &&
1414 sk_stream_memory_free(msk->last_snd) &&
1415 mptcp_subflow_active(mptcp_subflow_ctx(msk->last_snd)))
1416 return msk->last_snd;
1417
1418 /* pick the subflow with the lower wmem/wspace ratio */
1419 for (i = 0; i < 2; ++i) {
1420 send_info[i].ssk = NULL;
1421 send_info[i].ratio = -1;
1422 }
1423 mptcp_for_each_subflow(msk, subflow) {
1424 trace_mptcp_subflow_get_send(subflow);
1425 ssk = mptcp_subflow_tcp_sock(subflow);
1426 if (!mptcp_subflow_active(subflow))
1427 continue;
1428
1429 nr_active += !subflow->backup;
1430 if (!sk_stream_memory_free(subflow->tcp_sock) || !tcp_sk(ssk)->snd_wnd)
1431 continue;
1432
1433 pace = READ_ONCE(ssk->sk_pacing_rate);
1434 if (!pace)
1435 continue;
1436
1437 ratio = div_u64((u64)READ_ONCE(ssk->sk_wmem_queued) << 32,
1438 pace);
1439 if (ratio < send_info[subflow->backup].ratio) {
1440 send_info[subflow->backup].ssk = ssk;
1441 send_info[subflow->backup].ratio = ratio;
1442 }
1443 }
1444
1445 /* pick the best backup if no other subflow is active */
1446 if (!nr_active)
1447 send_info[0].ssk = send_info[1].ssk;
1448
1449 if (send_info[0].ssk) {
1450 msk->last_snd = send_info[0].ssk;
1451 msk->snd_burst = min_t(int, MPTCP_SEND_BURST_SIZE,
1452 tcp_sk(msk->last_snd)->snd_wnd);
1453 return msk->last_snd;
1454 }
1455
1456 return NULL;
1457 }
1458
mptcp_push_release(struct sock * sk,struct sock * ssk,struct mptcp_sendmsg_info * info)1459 static void mptcp_push_release(struct sock *sk, struct sock *ssk,
1460 struct mptcp_sendmsg_info *info)
1461 {
1462 mptcp_set_timeout(sk, ssk);
1463 tcp_push(ssk, 0, info->mss_now, tcp_sk(ssk)->nonagle, info->size_goal);
1464 release_sock(ssk);
1465 }
1466
__mptcp_push_pending(struct sock * sk,unsigned int flags)1467 static void __mptcp_push_pending(struct sock *sk, unsigned int flags)
1468 {
1469 struct sock *prev_ssk = NULL, *ssk = NULL;
1470 struct mptcp_sock *msk = mptcp_sk(sk);
1471 struct mptcp_sendmsg_info info = {
1472 .flags = flags,
1473 };
1474 struct mptcp_data_frag *dfrag;
1475 int len, copied = 0;
1476
1477 while ((dfrag = mptcp_send_head(sk))) {
1478 info.sent = dfrag->already_sent;
1479 info.limit = dfrag->data_len;
1480 len = dfrag->data_len - dfrag->already_sent;
1481 while (len > 0) {
1482 int ret = 0;
1483
1484 prev_ssk = ssk;
1485 mptcp_flush_join_list(msk);
1486 ssk = mptcp_subflow_get_send(msk);
1487
1488 /* try to keep the subflow socket lock across
1489 * consecutive xmit on the same socket
1490 */
1491 if (ssk != prev_ssk && prev_ssk)
1492 mptcp_push_release(sk, prev_ssk, &info);
1493 if (!ssk)
1494 goto out;
1495
1496 if (ssk != prev_ssk || !prev_ssk)
1497 lock_sock(ssk);
1498
1499 /* keep it simple and always provide a new skb for the
1500 * subflow, even if we will not use it when collapsing
1501 * on the pending one
1502 */
1503 if (!mptcp_alloc_tx_skb(sk, ssk)) {
1504 mptcp_push_release(sk, ssk, &info);
1505 goto out;
1506 }
1507
1508 ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
1509 if (ret <= 0) {
1510 mptcp_push_release(sk, ssk, &info);
1511 goto out;
1512 }
1513
1514 info.sent += ret;
1515 dfrag->already_sent += ret;
1516 msk->snd_nxt += ret;
1517 msk->snd_burst -= ret;
1518 msk->tx_pending_data -= ret;
1519 copied += ret;
1520 len -= ret;
1521 }
1522 WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1523 }
1524
1525 /* at this point we held the socket lock for the last subflow we used */
1526 if (ssk)
1527 mptcp_push_release(sk, ssk, &info);
1528
1529 out:
1530 if (copied) {
1531 /* start the timer, if it's not pending */
1532 if (!mptcp_timer_pending(sk))
1533 mptcp_reset_timer(sk);
1534 __mptcp_check_send_data_fin(sk);
1535 }
1536 }
1537
__mptcp_subflow_push_pending(struct sock * sk,struct sock * ssk)1538 static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
1539 {
1540 struct mptcp_sock *msk = mptcp_sk(sk);
1541 struct mptcp_sendmsg_info info;
1542 struct mptcp_data_frag *dfrag;
1543 struct sock *xmit_ssk;
1544 int len, copied = 0;
1545 bool first = true;
1546
1547 info.flags = 0;
1548 while ((dfrag = mptcp_send_head(sk))) {
1549 info.sent = dfrag->already_sent;
1550 info.limit = dfrag->data_len;
1551 len = dfrag->data_len - dfrag->already_sent;
1552 while (len > 0) {
1553 int ret = 0;
1554
1555 /* the caller already invoked the packet scheduler,
1556 * check for a different subflow usage only after
1557 * spooling the first chunk of data
1558 */
1559 xmit_ssk = first ? ssk : mptcp_subflow_get_send(mptcp_sk(sk));
1560 if (!xmit_ssk)
1561 goto out;
1562 if (xmit_ssk != ssk) {
1563 mptcp_subflow_delegate(mptcp_subflow_ctx(xmit_ssk));
1564 goto out;
1565 }
1566
1567 if (unlikely(mptcp_must_reclaim_memory(sk, ssk))) {
1568 __mptcp_update_wmem(sk);
1569 sk_mem_reclaim_partial(sk);
1570 }
1571 if (!__mptcp_alloc_tx_skb(sk, ssk, GFP_ATOMIC))
1572 goto out;
1573
1574 ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
1575 if (ret <= 0)
1576 goto out;
1577
1578 info.sent += ret;
1579 dfrag->already_sent += ret;
1580 msk->snd_nxt += ret;
1581 msk->snd_burst -= ret;
1582 msk->tx_pending_data -= ret;
1583 copied += ret;
1584 len -= ret;
1585 first = false;
1586 }
1587 WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
1588 }
1589
1590 out:
1591 /* __mptcp_alloc_tx_skb could have released some wmem and we are
1592 * not going to flush it via release_sock()
1593 */
1594 __mptcp_update_wmem(sk);
1595 if (copied) {
1596 mptcp_set_timeout(sk, ssk);
1597 tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
1598 info.size_goal);
1599 if (!mptcp_timer_pending(sk))
1600 mptcp_reset_timer(sk);
1601
1602 if (msk->snd_data_fin_enable &&
1603 msk->snd_nxt + 1 == msk->write_seq)
1604 mptcp_schedule_work(sk);
1605 }
1606 }
1607
mptcp_set_nospace(struct sock * sk)1608 static void mptcp_set_nospace(struct sock *sk)
1609 {
1610 /* enable autotune */
1611 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
1612
1613 /* will be cleared on avail space */
1614 set_bit(MPTCP_NOSPACE, &mptcp_sk(sk)->flags);
1615 }
1616
mptcp_sendmsg(struct sock * sk,struct msghdr * msg,size_t len)1617 static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
1618 {
1619 struct mptcp_sock *msk = mptcp_sk(sk);
1620 struct page_frag *pfrag;
1621 size_t copied = 0;
1622 int ret = 0;
1623 long timeo;
1624
1625 /* we don't support FASTOPEN yet */
1626 if (msg->msg_flags & MSG_FASTOPEN)
1627 return -EOPNOTSUPP;
1628
1629 /* silently ignore everything else */
1630 msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL;
1631
1632 mptcp_lock_sock(sk, __mptcp_wmem_reserve(sk, min_t(size_t, 1 << 20, len)));
1633
1634 timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
1635
1636 if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
1637 ret = sk_stream_wait_connect(sk, &timeo);
1638 if (ret)
1639 goto out;
1640 }
1641
1642 pfrag = sk_page_frag(sk);
1643
1644 while (msg_data_left(msg)) {
1645 int total_ts, frag_truesize = 0;
1646 struct mptcp_data_frag *dfrag;
1647 struct sk_buff_head skbs;
1648 bool dfrag_collapsed;
1649 size_t psize, offset;
1650
1651 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
1652 ret = -EPIPE;
1653 goto out;
1654 }
1655
1656 /* reuse tail pfrag, if possible, or carve a new one from the
1657 * page allocator
1658 */
1659 dfrag = mptcp_pending_tail(sk);
1660 dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag);
1661 if (!dfrag_collapsed) {
1662 if (!sk_stream_memory_free(sk))
1663 goto wait_for_memory;
1664
1665 if (!mptcp_page_frag_refill(sk, pfrag))
1666 goto wait_for_memory;
1667
1668 dfrag = mptcp_carve_data_frag(msk, pfrag, pfrag->offset);
1669 frag_truesize = dfrag->overhead;
1670 }
1671
1672 /* we do not bound vs wspace, to allow a single packet.
1673 * memory accounting will prevent execessive memory usage
1674 * anyway
1675 */
1676 offset = dfrag->offset + dfrag->data_len;
1677 psize = pfrag->size - offset;
1678 psize = min_t(size_t, psize, msg_data_left(msg));
1679 total_ts = psize + frag_truesize;
1680 __skb_queue_head_init(&skbs);
1681 if (!mptcp_tx_cache_refill(sk, psize, &skbs, &total_ts))
1682 goto wait_for_memory;
1683
1684 if (!mptcp_wmem_alloc(sk, total_ts)) {
1685 __skb_queue_purge(&skbs);
1686 goto wait_for_memory;
1687 }
1688
1689 skb_queue_splice_tail(&skbs, &msk->skb_tx_cache);
1690 if (copy_page_from_iter(dfrag->page, offset, psize,
1691 &msg->msg_iter) != psize) {
1692 mptcp_wmem_uncharge(sk, psize + frag_truesize);
1693 ret = -EFAULT;
1694 goto out;
1695 }
1696
1697 /* data successfully copied into the write queue */
1698 copied += psize;
1699 dfrag->data_len += psize;
1700 frag_truesize += psize;
1701 pfrag->offset += frag_truesize;
1702 WRITE_ONCE(msk->write_seq, msk->write_seq + psize);
1703 msk->tx_pending_data += psize;
1704
1705 /* charge data on mptcp pending queue to the msk socket
1706 * Note: we charge such data both to sk and ssk
1707 */
1708 sk_wmem_queued_add(sk, frag_truesize);
1709 if (!dfrag_collapsed) {
1710 get_page(dfrag->page);
1711 list_add_tail(&dfrag->list, &msk->rtx_queue);
1712 if (!msk->first_pending)
1713 WRITE_ONCE(msk->first_pending, dfrag);
1714 }
1715 pr_debug("msk=%p dfrag at seq=%llu len=%u sent=%u new=%d", msk,
1716 dfrag->data_seq, dfrag->data_len, dfrag->already_sent,
1717 !dfrag_collapsed);
1718
1719 continue;
1720
1721 wait_for_memory:
1722 mptcp_set_nospace(sk);
1723 __mptcp_push_pending(sk, msg->msg_flags);
1724 ret = sk_stream_wait_memory(sk, &timeo);
1725 if (ret)
1726 goto out;
1727 }
1728
1729 if (copied)
1730 __mptcp_push_pending(sk, msg->msg_flags);
1731
1732 out:
1733 release_sock(sk);
1734 return copied ? : ret;
1735 }
1736
mptcp_wait_data(struct sock * sk,long * timeo)1737 static void mptcp_wait_data(struct sock *sk, long *timeo)
1738 {
1739 DEFINE_WAIT_FUNC(wait, woken_wake_function);
1740 struct mptcp_sock *msk = mptcp_sk(sk);
1741
1742 add_wait_queue(sk_sleep(sk), &wait);
1743 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
1744
1745 sk_wait_event(sk, timeo,
1746 test_and_clear_bit(MPTCP_DATA_READY, &msk->flags), &wait);
1747
1748 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
1749 remove_wait_queue(sk_sleep(sk), &wait);
1750 }
1751
__mptcp_recvmsg_mskq(struct mptcp_sock * msk,struct msghdr * msg,size_t len,int flags)1752 static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
1753 struct msghdr *msg,
1754 size_t len, int flags)
1755 {
1756 struct sk_buff *skb, *tmp;
1757 int copied = 0;
1758
1759 skb_queue_walk_safe(&msk->receive_queue, skb, tmp) {
1760 u32 offset = MPTCP_SKB_CB(skb)->offset;
1761 u32 data_len = skb->len - offset;
1762 u32 count = min_t(size_t, len - copied, data_len);
1763 int err;
1764
1765 if (!(flags & MSG_TRUNC)) {
1766 err = skb_copy_datagram_msg(skb, offset, msg, count);
1767 if (unlikely(err < 0)) {
1768 if (!copied)
1769 return err;
1770 break;
1771 }
1772 }
1773
1774 copied += count;
1775
1776 if (count < data_len) {
1777 if (!(flags & MSG_PEEK))
1778 MPTCP_SKB_CB(skb)->offset += count;
1779 break;
1780 }
1781
1782 if (!(flags & MSG_PEEK)) {
1783 /* we will bulk release the skb memory later */
1784 skb->destructor = NULL;
1785 msk->rmem_released += skb->truesize;
1786 __skb_unlink(skb, &msk->receive_queue);
1787 __kfree_skb(skb);
1788 }
1789
1790 if (copied >= len)
1791 break;
1792 }
1793
1794 return copied;
1795 }
1796
1797 /* receive buffer autotuning. See tcp_rcv_space_adjust for more information.
1798 *
1799 * Only difference: Use highest rtt estimate of the subflows in use.
1800 */
mptcp_rcv_space_adjust(struct mptcp_sock * msk,int copied)1801 static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
1802 {
1803 struct mptcp_subflow_context *subflow;
1804 struct sock *sk = (struct sock *)msk;
1805 u32 time, advmss = 1;
1806 u64 rtt_us, mstamp;
1807
1808 sock_owned_by_me(sk);
1809
1810 if (copied <= 0)
1811 return;
1812
1813 msk->rcvq_space.copied += copied;
1814
1815 mstamp = div_u64(tcp_clock_ns(), NSEC_PER_USEC);
1816 time = tcp_stamp_us_delta(mstamp, msk->rcvq_space.time);
1817
1818 rtt_us = msk->rcvq_space.rtt_us;
1819 if (rtt_us && time < (rtt_us >> 3))
1820 return;
1821
1822 rtt_us = 0;
1823 mptcp_for_each_subflow(msk, subflow) {
1824 const struct tcp_sock *tp;
1825 u64 sf_rtt_us;
1826 u32 sf_advmss;
1827
1828 tp = tcp_sk(mptcp_subflow_tcp_sock(subflow));
1829
1830 sf_rtt_us = READ_ONCE(tp->rcv_rtt_est.rtt_us);
1831 sf_advmss = READ_ONCE(tp->advmss);
1832
1833 rtt_us = max(sf_rtt_us, rtt_us);
1834 advmss = max(sf_advmss, advmss);
1835 }
1836
1837 msk->rcvq_space.rtt_us = rtt_us;
1838 if (time < (rtt_us >> 3) || rtt_us == 0)
1839 return;
1840
1841 if (msk->rcvq_space.copied <= msk->rcvq_space.space)
1842 goto new_measure;
1843
1844 if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&
1845 !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
1846 int rcvmem, rcvbuf;
1847 u64 rcvwin, grow;
1848
1849 rcvwin = ((u64)msk->rcvq_space.copied << 1) + 16 * advmss;
1850
1851 grow = rcvwin * (msk->rcvq_space.copied - msk->rcvq_space.space);
1852
1853 do_div(grow, msk->rcvq_space.space);
1854 rcvwin += (grow << 1);
1855
1856 rcvmem = SKB_TRUESIZE(advmss + MAX_TCP_HEADER);
1857 while (tcp_win_from_space(sk, rcvmem) < advmss)
1858 rcvmem += 128;
1859
1860 do_div(rcvwin, advmss);
1861 rcvbuf = min_t(u64, rcvwin * rcvmem,
1862 sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
1863
1864 if (rcvbuf > sk->sk_rcvbuf) {
1865 u32 window_clamp;
1866
1867 window_clamp = tcp_win_from_space(sk, rcvbuf);
1868 WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);
1869
1870 /* Make subflows follow along. If we do not do this, we
1871 * get drops at subflow level if skbs can't be moved to
1872 * the mptcp rx queue fast enough (announced rcv_win can
1873 * exceed ssk->sk_rcvbuf).
1874 */
1875 mptcp_for_each_subflow(msk, subflow) {
1876 struct sock *ssk;
1877 bool slow;
1878
1879 ssk = mptcp_subflow_tcp_sock(subflow);
1880 slow = lock_sock_fast(ssk);
1881 WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf);
1882 tcp_sk(ssk)->window_clamp = window_clamp;
1883 tcp_cleanup_rbuf(ssk, 1);
1884 unlock_sock_fast(ssk, slow);
1885 }
1886 }
1887 }
1888
1889 msk->rcvq_space.space = msk->rcvq_space.copied;
1890 new_measure:
1891 msk->rcvq_space.copied = 0;
1892 msk->rcvq_space.time = mstamp;
1893 }
1894
__mptcp_update_rmem(struct sock * sk)1895 static void __mptcp_update_rmem(struct sock *sk)
1896 {
1897 struct mptcp_sock *msk = mptcp_sk(sk);
1898
1899 if (!msk->rmem_released)
1900 return;
1901
1902 atomic_sub(msk->rmem_released, &sk->sk_rmem_alloc);
1903 sk_mem_uncharge(sk, msk->rmem_released);
1904 msk->rmem_released = 0;
1905 }
1906
__mptcp_splice_receive_queue(struct sock * sk)1907 static void __mptcp_splice_receive_queue(struct sock *sk)
1908 {
1909 struct mptcp_sock *msk = mptcp_sk(sk);
1910
1911 skb_queue_splice_tail_init(&sk->sk_receive_queue, &msk->receive_queue);
1912 }
1913
__mptcp_move_skbs(struct mptcp_sock * msk)1914 static bool __mptcp_move_skbs(struct mptcp_sock *msk)
1915 {
1916 struct sock *sk = (struct sock *)msk;
1917 unsigned int moved = 0;
1918 bool ret, done;
1919
1920 mptcp_flush_join_list(msk);
1921 do {
1922 struct sock *ssk = mptcp_subflow_recv_lookup(msk);
1923 bool slowpath;
1924
1925 /* we can have data pending in the subflows only if the msk
1926 * receive buffer was full at subflow_data_ready() time,
1927 * that is an unlikely slow path.
1928 */
1929 if (likely(!ssk))
1930 break;
1931
1932 slowpath = lock_sock_fast(ssk);
1933 mptcp_data_lock(sk);
1934 __mptcp_update_rmem(sk);
1935 done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved);
1936 mptcp_data_unlock(sk);
1937 tcp_cleanup_rbuf(ssk, moved);
1938 unlock_sock_fast(ssk, slowpath);
1939 } while (!done);
1940
1941 /* acquire the data lock only if some input data is pending */
1942 ret = moved > 0;
1943 if (!RB_EMPTY_ROOT(&msk->out_of_order_queue) ||
1944 !skb_queue_empty_lockless(&sk->sk_receive_queue)) {
1945 mptcp_data_lock(sk);
1946 __mptcp_update_rmem(sk);
1947 ret |= __mptcp_ofo_queue(msk);
1948 __mptcp_splice_receive_queue(sk);
1949 mptcp_data_unlock(sk);
1950 mptcp_cleanup_rbuf(msk);
1951 }
1952 if (ret)
1953 mptcp_check_data_fin((struct sock *)msk);
1954 return !skb_queue_empty(&msk->receive_queue);
1955 }
1956
mptcp_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int nonblock,int flags,int * addr_len)1957 static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
1958 int nonblock, int flags, int *addr_len)
1959 {
1960 struct mptcp_sock *msk = mptcp_sk(sk);
1961 int copied = 0;
1962 int target;
1963 long timeo;
1964
1965 /* MSG_ERRQUEUE is really a no-op till we support IP_RECVERR */
1966 if (unlikely(flags & MSG_ERRQUEUE))
1967 return inet_recv_error(sk, msg, len, addr_len);
1968
1969 mptcp_lock_sock(sk, __mptcp_splice_receive_queue(sk));
1970 if (unlikely(sk->sk_state == TCP_LISTEN)) {
1971 copied = -ENOTCONN;
1972 goto out_err;
1973 }
1974
1975 timeo = sock_rcvtimeo(sk, nonblock);
1976
1977 len = min_t(size_t, len, INT_MAX);
1978 target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1979
1980 while (copied < len) {
1981 int bytes_read;
1982
1983 bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied, flags);
1984 if (unlikely(bytes_read < 0)) {
1985 if (!copied)
1986 copied = bytes_read;
1987 goto out_err;
1988 }
1989
1990 copied += bytes_read;
1991
1992 /* be sure to advertise window change */
1993 mptcp_cleanup_rbuf(msk);
1994
1995 if (skb_queue_empty(&msk->receive_queue) && __mptcp_move_skbs(msk))
1996 continue;
1997
1998 /* only the master socket status is relevant here. The exit
1999 * conditions mirror closely tcp_recvmsg()
2000 */
2001 if (copied >= target)
2002 break;
2003
2004 if (copied) {
2005 if (sk->sk_err ||
2006 sk->sk_state == TCP_CLOSE ||
2007 (sk->sk_shutdown & RCV_SHUTDOWN) ||
2008 !timeo ||
2009 signal_pending(current))
2010 break;
2011 } else {
2012 if (sk->sk_err) {
2013 copied = sock_error(sk);
2014 break;
2015 }
2016
2017 if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
2018 mptcp_check_for_eof(msk);
2019
2020 if (sk->sk_shutdown & RCV_SHUTDOWN) {
2021 /* race breaker: the shutdown could be after the
2022 * previous receive queue check
2023 */
2024 if (__mptcp_move_skbs(msk))
2025 continue;
2026 break;
2027 }
2028
2029 if (sk->sk_state == TCP_CLOSE) {
2030 copied = -ENOTCONN;
2031 break;
2032 }
2033
2034 if (!timeo) {
2035 copied = -EAGAIN;
2036 break;
2037 }
2038
2039 if (signal_pending(current)) {
2040 copied = sock_intr_errno(timeo);
2041 break;
2042 }
2043 }
2044
2045 pr_debug("block timeout %ld", timeo);
2046 mptcp_wait_data(sk, &timeo);
2047 }
2048
2049 if (skb_queue_empty_lockless(&sk->sk_receive_queue) &&
2050 skb_queue_empty(&msk->receive_queue)) {
2051 /* entire backlog drained, clear DATA_READY. */
2052 clear_bit(MPTCP_DATA_READY, &msk->flags);
2053
2054 /* .. race-breaker: ssk might have gotten new data
2055 * after last __mptcp_move_skbs() returned false.
2056 */
2057 if (unlikely(__mptcp_move_skbs(msk)))
2058 set_bit(MPTCP_DATA_READY, &msk->flags);
2059 } else if (unlikely(!test_bit(MPTCP_DATA_READY, &msk->flags))) {
2060 /* data to read but mptcp_wait_data() cleared DATA_READY */
2061 set_bit(MPTCP_DATA_READY, &msk->flags);
2062 }
2063 out_err:
2064 pr_debug("msk=%p data_ready=%d rx queue empty=%d copied=%d",
2065 msk, test_bit(MPTCP_DATA_READY, &msk->flags),
2066 skb_queue_empty_lockless(&sk->sk_receive_queue), copied);
2067 if (!(flags & MSG_PEEK))
2068 mptcp_rcv_space_adjust(msk, copied);
2069
2070 release_sock(sk);
2071 return copied;
2072 }
2073
mptcp_retransmit_timer(struct timer_list * t)2074 static void mptcp_retransmit_timer(struct timer_list *t)
2075 {
2076 struct inet_connection_sock *icsk = from_timer(icsk, t,
2077 icsk_retransmit_timer);
2078 struct sock *sk = &icsk->icsk_inet.sk;
2079 struct mptcp_sock *msk = mptcp_sk(sk);
2080
2081 bh_lock_sock(sk);
2082 if (!sock_owned_by_user(sk)) {
2083 /* we need a process context to retransmit */
2084 if (!test_and_set_bit(MPTCP_WORK_RTX, &msk->flags))
2085 mptcp_schedule_work(sk);
2086 } else {
2087 /* delegate our work to tcp_release_cb() */
2088 set_bit(MPTCP_RETRANSMIT, &msk->flags);
2089 }
2090 bh_unlock_sock(sk);
2091 sock_put(sk);
2092 }
2093
mptcp_timeout_timer(struct timer_list * t)2094 static void mptcp_timeout_timer(struct timer_list *t)
2095 {
2096 struct sock *sk = from_timer(sk, t, sk_timer);
2097
2098 mptcp_schedule_work(sk);
2099 sock_put(sk);
2100 }
2101
2102 /* Find an idle subflow. Return NULL if there is unacked data at tcp
2103 * level.
2104 *
2105 * A backup subflow is returned only if that is the only kind available.
2106 */
mptcp_subflow_get_retrans(const struct mptcp_sock * msk)2107 static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
2108 {
2109 struct mptcp_subflow_context *subflow;
2110 struct sock *backup = NULL;
2111
2112 sock_owned_by_me((const struct sock *)msk);
2113
2114 if (__mptcp_check_fallback(msk))
2115 return NULL;
2116
2117 mptcp_for_each_subflow(msk, subflow) {
2118 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2119
2120 if (!mptcp_subflow_active(subflow))
2121 continue;
2122
2123 /* still data outstanding at TCP level? Don't retransmit. */
2124 if (!tcp_write_queue_empty(ssk)) {
2125 if (inet_csk(ssk)->icsk_ca_state >= TCP_CA_Loss)
2126 continue;
2127 return NULL;
2128 }
2129
2130 if (subflow->backup) {
2131 if (!backup)
2132 backup = ssk;
2133 continue;
2134 }
2135
2136 return ssk;
2137 }
2138
2139 return backup;
2140 }
2141
mptcp_dispose_initial_subflow(struct mptcp_sock * msk)2142 static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk)
2143 {
2144 if (msk->subflow) {
2145 iput(SOCK_INODE(msk->subflow));
2146 msk->subflow = NULL;
2147 }
2148 }
2149
2150 /* subflow sockets can be either outgoing (connect) or incoming
2151 * (accept).
2152 *
2153 * Outgoing subflows use in-kernel sockets.
2154 * Incoming subflows do not have their own 'struct socket' allocated,
2155 * so we need to use tcp_close() after detaching them from the mptcp
2156 * parent socket.
2157 */
__mptcp_close_ssk(struct sock * sk,struct sock * ssk,struct mptcp_subflow_context * subflow)2158 static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2159 struct mptcp_subflow_context *subflow)
2160 {
2161 struct mptcp_sock *msk = mptcp_sk(sk);
2162
2163 list_del(&subflow->node);
2164
2165 lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
2166
2167 /* if we are invoked by the msk cleanup code, the subflow is
2168 * already orphaned
2169 */
2170 if (ssk->sk_socket)
2171 sock_orphan(ssk);
2172
2173 subflow->disposable = 1;
2174
2175 /* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
2176 * the ssk has been already destroyed, we just need to release the
2177 * reference owned by msk;
2178 */
2179 if (!inet_csk(ssk)->icsk_ulp_ops) {
2180 kfree_rcu(subflow, rcu);
2181 } else {
2182 /* otherwise tcp will dispose of the ssk and subflow ctx */
2183 __tcp_close(ssk, 0);
2184
2185 /* close acquired an extra ref */
2186 __sock_put(ssk);
2187 }
2188 release_sock(ssk);
2189
2190 sock_put(ssk);
2191
2192 if (ssk == msk->last_snd)
2193 msk->last_snd = NULL;
2194
2195 if (ssk == msk->ack_hint)
2196 msk->ack_hint = NULL;
2197
2198 if (ssk == msk->first)
2199 msk->first = NULL;
2200
2201 if (msk->subflow && ssk == msk->subflow->sk)
2202 mptcp_dispose_initial_subflow(msk);
2203 }
2204
mptcp_close_ssk(struct sock * sk,struct sock * ssk,struct mptcp_subflow_context * subflow)2205 void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
2206 struct mptcp_subflow_context *subflow)
2207 {
2208 if (sk->sk_state == TCP_ESTABLISHED)
2209 mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
2210 __mptcp_close_ssk(sk, ssk, subflow);
2211 }
2212
mptcp_sync_mss(struct sock * sk,u32 pmtu)2213 static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
2214 {
2215 return 0;
2216 }
2217
__mptcp_close_subflow(struct mptcp_sock * msk)2218 static void __mptcp_close_subflow(struct mptcp_sock *msk)
2219 {
2220 struct mptcp_subflow_context *subflow, *tmp;
2221
2222 might_sleep();
2223
2224 list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
2225 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2226
2227 if (inet_sk_state_load(ssk) != TCP_CLOSE)
2228 continue;
2229
2230 /* 'subflow_data_ready' will re-sched once rx queue is empty */
2231 if (!skb_queue_empty_lockless(&ssk->sk_receive_queue))
2232 continue;
2233
2234 mptcp_close_ssk((struct sock *)msk, ssk, subflow);
2235 }
2236 }
2237
mptcp_check_close_timeout(const struct sock * sk)2238 static bool mptcp_check_close_timeout(const struct sock *sk)
2239 {
2240 s32 delta = tcp_jiffies32 - inet_csk(sk)->icsk_mtup.probe_timestamp;
2241 struct mptcp_subflow_context *subflow;
2242
2243 if (delta >= TCP_TIMEWAIT_LEN)
2244 return true;
2245
2246 /* if all subflows are in closed status don't bother with additional
2247 * timeout
2248 */
2249 mptcp_for_each_subflow(mptcp_sk(sk), subflow) {
2250 if (inet_sk_state_load(mptcp_subflow_tcp_sock(subflow)) !=
2251 TCP_CLOSE)
2252 return false;
2253 }
2254 return true;
2255 }
2256
mptcp_check_fastclose(struct mptcp_sock * msk)2257 static void mptcp_check_fastclose(struct mptcp_sock *msk)
2258 {
2259 struct mptcp_subflow_context *subflow, *tmp;
2260 struct sock *sk = &msk->sk.icsk_inet.sk;
2261
2262 if (likely(!READ_ONCE(msk->rcv_fastclose)))
2263 return;
2264
2265 mptcp_token_destroy(msk);
2266
2267 list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
2268 struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
2269
2270 lock_sock(tcp_sk);
2271 if (tcp_sk->sk_state != TCP_CLOSE) {
2272 tcp_send_active_reset(tcp_sk, GFP_ATOMIC);
2273 tcp_set_state(tcp_sk, TCP_CLOSE);
2274 }
2275 release_sock(tcp_sk);
2276 }
2277
2278 inet_sk_state_store(sk, TCP_CLOSE);
2279 sk->sk_shutdown = SHUTDOWN_MASK;
2280 smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
2281 set_bit(MPTCP_DATA_READY, &msk->flags);
2282 set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags);
2283
2284 mptcp_close_wake_up(sk);
2285 }
2286
__mptcp_retrans(struct sock * sk)2287 static void __mptcp_retrans(struct sock *sk)
2288 {
2289 struct mptcp_sock *msk = mptcp_sk(sk);
2290 struct mptcp_sendmsg_info info = {};
2291 struct mptcp_data_frag *dfrag;
2292 size_t copied = 0;
2293 struct sock *ssk;
2294 int ret;
2295
2296 __mptcp_clean_una_wakeup(sk);
2297 dfrag = mptcp_rtx_head(sk);
2298 if (!dfrag) {
2299 if (mptcp_data_fin_enabled(msk)) {
2300 struct inet_connection_sock *icsk = inet_csk(sk);
2301
2302 icsk->icsk_retransmits++;
2303 mptcp_set_datafin_timeout(sk);
2304 mptcp_send_ack(msk);
2305
2306 goto reset_timer;
2307 }
2308
2309 return;
2310 }
2311
2312 ssk = mptcp_subflow_get_retrans(msk);
2313 if (!ssk)
2314 goto reset_timer;
2315
2316 lock_sock(ssk);
2317
2318 /* limit retransmission to the bytes already sent on some subflows */
2319 info.sent = 0;
2320 info.limit = dfrag->already_sent;
2321 while (info.sent < dfrag->already_sent) {
2322 if (!mptcp_alloc_tx_skb(sk, ssk))
2323 break;
2324
2325 ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
2326 if (ret <= 0)
2327 break;
2328
2329 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS);
2330 copied += ret;
2331 info.sent += ret;
2332 }
2333 if (copied)
2334 tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
2335 info.size_goal);
2336
2337 mptcp_set_timeout(sk, ssk);
2338 release_sock(ssk);
2339
2340 reset_timer:
2341 if (!mptcp_timer_pending(sk))
2342 mptcp_reset_timer(sk);
2343 }
2344
mptcp_worker(struct work_struct * work)2345 static void mptcp_worker(struct work_struct *work)
2346 {
2347 struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
2348 struct sock *sk = &msk->sk.icsk_inet.sk;
2349 int state;
2350
2351 lock_sock(sk);
2352 state = sk->sk_state;
2353 if (unlikely(state == TCP_CLOSE))
2354 goto unlock;
2355
2356 mptcp_check_data_fin_ack(sk);
2357 mptcp_flush_join_list(msk);
2358
2359 mptcp_check_fastclose(msk);
2360
2361 if (msk->pm.status)
2362 mptcp_pm_nl_work(msk);
2363
2364 if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
2365 mptcp_check_for_eof(msk);
2366
2367 __mptcp_check_send_data_fin(sk);
2368 mptcp_check_data_fin(sk);
2369
2370 /* There is no point in keeping around an orphaned sk timedout or
2371 * closed, but we need the msk around to reply to incoming DATA_FIN,
2372 * even if it is orphaned and in FIN_WAIT2 state
2373 */
2374 if (sock_flag(sk, SOCK_DEAD) &&
2375 (mptcp_check_close_timeout(sk) || sk->sk_state == TCP_CLOSE)) {
2376 inet_sk_state_store(sk, TCP_CLOSE);
2377 __mptcp_destroy_sock(sk);
2378 goto unlock;
2379 }
2380
2381 if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
2382 __mptcp_close_subflow(msk);
2383
2384 if (test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags))
2385 __mptcp_retrans(sk);
2386
2387 unlock:
2388 release_sock(sk);
2389 sock_put(sk);
2390 }
2391
__mptcp_init_sock(struct sock * sk)2392 static int __mptcp_init_sock(struct sock *sk)
2393 {
2394 struct mptcp_sock *msk = mptcp_sk(sk);
2395
2396 spin_lock_init(&msk->join_list_lock);
2397
2398 INIT_LIST_HEAD(&msk->conn_list);
2399 INIT_LIST_HEAD(&msk->join_list);
2400 INIT_LIST_HEAD(&msk->rtx_queue);
2401 INIT_WORK(&msk->work, mptcp_worker);
2402 __skb_queue_head_init(&msk->receive_queue);
2403 __skb_queue_head_init(&msk->skb_tx_cache);
2404 msk->out_of_order_queue = RB_ROOT;
2405 msk->first_pending = NULL;
2406 msk->wmem_reserved = 0;
2407 msk->rmem_released = 0;
2408 msk->tx_pending_data = 0;
2409 msk->size_goal_cache = TCP_BASE_MSS;
2410
2411 msk->ack_hint = NULL;
2412 msk->first = NULL;
2413 inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss;
2414
2415 mptcp_pm_data_init(msk);
2416
2417 /* re-use the csk retrans timer for MPTCP-level retrans */
2418 timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0);
2419 timer_setup(&sk->sk_timer, mptcp_timeout_timer, 0);
2420
2421 tcp_assign_congestion_control(sk);
2422
2423 return 0;
2424 }
2425
mptcp_init_sock(struct sock * sk)2426 static int mptcp_init_sock(struct sock *sk)
2427 {
2428 struct net *net = sock_net(sk);
2429 int ret;
2430
2431 ret = __mptcp_init_sock(sk);
2432 if (ret)
2433 return ret;
2434
2435 if (!mptcp_is_enabled(net))
2436 return -ENOPROTOOPT;
2437
2438 if (unlikely(!net->mib.mptcp_statistics) && !mptcp_mib_alloc(net))
2439 return -ENOMEM;
2440
2441 ret = __mptcp_socket_create(mptcp_sk(sk));
2442 if (ret)
2443 return ret;
2444
2445 sk_sockets_allocated_inc(sk);
2446 sk->sk_rcvbuf = sock_net(sk)->ipv4.sysctl_tcp_rmem[1];
2447 sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[1];
2448
2449 return 0;
2450 }
2451
__mptcp_clear_xmit(struct sock * sk)2452 static void __mptcp_clear_xmit(struct sock *sk)
2453 {
2454 struct mptcp_sock *msk = mptcp_sk(sk);
2455 struct mptcp_data_frag *dtmp, *dfrag;
2456 struct sk_buff *skb;
2457
2458 WRITE_ONCE(msk->first_pending, NULL);
2459 list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list)
2460 dfrag_clear(sk, dfrag);
2461 while ((skb = __skb_dequeue(&msk->skb_tx_cache)) != NULL) {
2462 sk->sk_forward_alloc += skb->truesize;
2463 kfree_skb(skb);
2464 }
2465 }
2466
mptcp_cancel_work(struct sock * sk)2467 static void mptcp_cancel_work(struct sock *sk)
2468 {
2469 struct mptcp_sock *msk = mptcp_sk(sk);
2470
2471 if (cancel_work_sync(&msk->work))
2472 __sock_put(sk);
2473 }
2474
mptcp_subflow_shutdown(struct sock * sk,struct sock * ssk,int how)2475 void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
2476 {
2477 lock_sock(ssk);
2478
2479 switch (ssk->sk_state) {
2480 case TCP_LISTEN:
2481 if (!(how & RCV_SHUTDOWN))
2482 break;
2483 fallthrough;
2484 case TCP_SYN_SENT:
2485 tcp_disconnect(ssk, O_NONBLOCK);
2486 break;
2487 default:
2488 if (__mptcp_check_fallback(mptcp_sk(sk))) {
2489 pr_debug("Fallback");
2490 ssk->sk_shutdown |= how;
2491 tcp_shutdown(ssk, how);
2492 } else {
2493 pr_debug("Sending DATA_FIN on subflow %p", ssk);
2494 mptcp_set_timeout(sk, ssk);
2495 tcp_send_ack(ssk);
2496 if (!mptcp_timer_pending(sk))
2497 mptcp_reset_timer(sk);
2498 }
2499 break;
2500 }
2501
2502 release_sock(ssk);
2503 }
2504
2505 static const unsigned char new_state[16] = {
2506 /* current state: new state: action: */
2507 [0 /* (Invalid) */] = TCP_CLOSE,
2508 [TCP_ESTABLISHED] = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2509 [TCP_SYN_SENT] = TCP_CLOSE,
2510 [TCP_SYN_RECV] = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
2511 [TCP_FIN_WAIT1] = TCP_FIN_WAIT1,
2512 [TCP_FIN_WAIT2] = TCP_FIN_WAIT2,
2513 [TCP_TIME_WAIT] = TCP_CLOSE, /* should not happen ! */
2514 [TCP_CLOSE] = TCP_CLOSE,
2515 [TCP_CLOSE_WAIT] = TCP_LAST_ACK | TCP_ACTION_FIN,
2516 [TCP_LAST_ACK] = TCP_LAST_ACK,
2517 [TCP_LISTEN] = TCP_CLOSE,
2518 [TCP_CLOSING] = TCP_CLOSING,
2519 [TCP_NEW_SYN_RECV] = TCP_CLOSE, /* should not happen ! */
2520 };
2521
mptcp_close_state(struct sock * sk)2522 static int mptcp_close_state(struct sock *sk)
2523 {
2524 int next = (int)new_state[sk->sk_state];
2525 int ns = next & TCP_STATE_MASK;
2526
2527 inet_sk_state_store(sk, ns);
2528
2529 return next & TCP_ACTION_FIN;
2530 }
2531
__mptcp_check_send_data_fin(struct sock * sk)2532 static void __mptcp_check_send_data_fin(struct sock *sk)
2533 {
2534 struct mptcp_subflow_context *subflow;
2535 struct mptcp_sock *msk = mptcp_sk(sk);
2536
2537 pr_debug("msk=%p snd_data_fin_enable=%d pending=%d snd_nxt=%llu write_seq=%llu",
2538 msk, msk->snd_data_fin_enable, !!mptcp_send_head(sk),
2539 msk->snd_nxt, msk->write_seq);
2540
2541 /* we still need to enqueue subflows or not really shutting down,
2542 * skip this
2543 */
2544 if (!msk->snd_data_fin_enable || msk->snd_nxt + 1 != msk->write_seq ||
2545 mptcp_send_head(sk))
2546 return;
2547
2548 WRITE_ONCE(msk->snd_nxt, msk->write_seq);
2549
2550 /* fallback socket will not get data_fin/ack, can move to the next
2551 * state now
2552 */
2553 if (__mptcp_check_fallback(msk)) {
2554 if ((1 << sk->sk_state) & (TCPF_CLOSING | TCPF_LAST_ACK)) {
2555 inet_sk_state_store(sk, TCP_CLOSE);
2556 mptcp_close_wake_up(sk);
2557 } else if (sk->sk_state == TCP_FIN_WAIT1) {
2558 inet_sk_state_store(sk, TCP_FIN_WAIT2);
2559 }
2560 }
2561
2562 mptcp_flush_join_list(msk);
2563 mptcp_for_each_subflow(msk, subflow) {
2564 struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
2565
2566 mptcp_subflow_shutdown(sk, tcp_sk, SEND_SHUTDOWN);
2567 }
2568 }
2569
__mptcp_wr_shutdown(struct sock * sk)2570 static void __mptcp_wr_shutdown(struct sock *sk)
2571 {
2572 struct mptcp_sock *msk = mptcp_sk(sk);
2573
2574 pr_debug("msk=%p snd_data_fin_enable=%d shutdown=%x state=%d pending=%d",
2575 msk, msk->snd_data_fin_enable, sk->sk_shutdown, sk->sk_state,
2576 !!mptcp_send_head(sk));
2577
2578 /* will be ignored by fallback sockets */
2579 WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
2580 WRITE_ONCE(msk->snd_data_fin_enable, 1);
2581
2582 __mptcp_check_send_data_fin(sk);
2583 }
2584
__mptcp_destroy_sock(struct sock * sk)2585 static void __mptcp_destroy_sock(struct sock *sk)
2586 {
2587 struct mptcp_subflow_context *subflow, *tmp;
2588 struct mptcp_sock *msk = mptcp_sk(sk);
2589 LIST_HEAD(conn_list);
2590
2591 pr_debug("msk=%p", msk);
2592
2593 might_sleep();
2594
2595 /* be sure to always acquire the join list lock, to sync vs
2596 * mptcp_finish_join().
2597 */
2598 spin_lock_bh(&msk->join_list_lock);
2599 list_splice_tail_init(&msk->join_list, &msk->conn_list);
2600 spin_unlock_bh(&msk->join_list_lock);
2601 list_splice_init(&msk->conn_list, &conn_list);
2602
2603 sk_stop_timer(sk, &msk->sk.icsk_retransmit_timer);
2604 sk_stop_timer(sk, &sk->sk_timer);
2605 msk->pm.status = 0;
2606
2607 list_for_each_entry_safe(subflow, tmp, &conn_list, node) {
2608 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2609 __mptcp_close_ssk(sk, ssk, subflow);
2610 }
2611
2612 sk->sk_prot->destroy(sk);
2613
2614 WARN_ON_ONCE(msk->wmem_reserved);
2615 WARN_ON_ONCE(msk->rmem_released);
2616 sk_stream_kill_queues(sk);
2617 xfrm_sk_free_policy(sk);
2618
2619 tcp_cleanup_congestion_control(sk);
2620 sk_refcnt_debug_release(sk);
2621 mptcp_dispose_initial_subflow(msk);
2622 sock_put(sk);
2623 }
2624
mptcp_close(struct sock * sk,long timeout)2625 static void mptcp_close(struct sock *sk, long timeout)
2626 {
2627 struct mptcp_subflow_context *subflow;
2628 bool do_cancel_work = false;
2629
2630 lock_sock(sk);
2631 sk->sk_shutdown = SHUTDOWN_MASK;
2632
2633 if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
2634 inet_sk_state_store(sk, TCP_CLOSE);
2635 goto cleanup;
2636 }
2637
2638 if (mptcp_close_state(sk))
2639 __mptcp_wr_shutdown(sk);
2640
2641 sk_stream_wait_close(sk, timeout);
2642
2643 cleanup:
2644 /* orphan all the subflows */
2645 inet_csk(sk)->icsk_mtup.probe_timestamp = tcp_jiffies32;
2646 mptcp_for_each_subflow(mptcp_sk(sk), subflow) {
2647 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2648 bool slow = lock_sock_fast(ssk);
2649
2650 sock_orphan(ssk);
2651 unlock_sock_fast(ssk, slow);
2652 }
2653 sock_orphan(sk);
2654
2655 sock_hold(sk);
2656 pr_debug("msk=%p state=%d", sk, sk->sk_state);
2657 if (sk->sk_state == TCP_CLOSE) {
2658 __mptcp_destroy_sock(sk);
2659 do_cancel_work = true;
2660 } else {
2661 sk_reset_timer(sk, &sk->sk_timer, jiffies + TCP_TIMEWAIT_LEN);
2662 }
2663 release_sock(sk);
2664 if (do_cancel_work)
2665 mptcp_cancel_work(sk);
2666
2667 if (mptcp_sk(sk)->token)
2668 mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);
2669
2670 sock_put(sk);
2671 }
2672
mptcp_copy_inaddrs(struct sock * msk,const struct sock * ssk)2673 static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
2674 {
2675 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
2676 const struct ipv6_pinfo *ssk6 = inet6_sk(ssk);
2677 struct ipv6_pinfo *msk6 = inet6_sk(msk);
2678
2679 msk->sk_v6_daddr = ssk->sk_v6_daddr;
2680 msk->sk_v6_rcv_saddr = ssk->sk_v6_rcv_saddr;
2681
2682 if (msk6 && ssk6) {
2683 msk6->saddr = ssk6->saddr;
2684 msk6->flow_label = ssk6->flow_label;
2685 }
2686 #endif
2687
2688 inet_sk(msk)->inet_num = inet_sk(ssk)->inet_num;
2689 inet_sk(msk)->inet_dport = inet_sk(ssk)->inet_dport;
2690 inet_sk(msk)->inet_sport = inet_sk(ssk)->inet_sport;
2691 inet_sk(msk)->inet_daddr = inet_sk(ssk)->inet_daddr;
2692 inet_sk(msk)->inet_saddr = inet_sk(ssk)->inet_saddr;
2693 inet_sk(msk)->inet_rcv_saddr = inet_sk(ssk)->inet_rcv_saddr;
2694 }
2695
mptcp_disconnect(struct sock * sk,int flags)2696 static int mptcp_disconnect(struct sock *sk, int flags)
2697 {
2698 struct mptcp_subflow_context *subflow;
2699 struct mptcp_sock *msk = mptcp_sk(sk);
2700
2701 mptcp_do_flush_join_list(msk);
2702
2703 mptcp_for_each_subflow(msk, subflow) {
2704 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
2705
2706 lock_sock(ssk);
2707 tcp_disconnect(ssk, flags);
2708 release_sock(ssk);
2709 }
2710 return 0;
2711 }
2712
2713 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
mptcp_inet6_sk(const struct sock * sk)2714 static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
2715 {
2716 unsigned int offset = sizeof(struct mptcp6_sock) - sizeof(struct ipv6_pinfo);
2717
2718 return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
2719 }
2720 #endif
2721
mptcp_sk_clone(const struct sock * sk,const struct mptcp_options_received * mp_opt,struct request_sock * req)2722 struct sock *mptcp_sk_clone(const struct sock *sk,
2723 const struct mptcp_options_received *mp_opt,
2724 struct request_sock *req)
2725 {
2726 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
2727 struct sock *nsk = sk_clone_lock(sk, GFP_ATOMIC);
2728 struct mptcp_sock *msk;
2729 u64 ack_seq;
2730
2731 if (!nsk)
2732 return NULL;
2733
2734 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
2735 if (nsk->sk_family == AF_INET6)
2736 inet_sk(nsk)->pinet6 = mptcp_inet6_sk(nsk);
2737 #endif
2738
2739 __mptcp_init_sock(nsk);
2740
2741 msk = mptcp_sk(nsk);
2742 msk->local_key = subflow_req->local_key;
2743 msk->token = subflow_req->token;
2744 msk->subflow = NULL;
2745 WRITE_ONCE(msk->fully_established, false);
2746
2747 msk->write_seq = subflow_req->idsn + 1;
2748 msk->snd_nxt = msk->write_seq;
2749 msk->snd_una = msk->write_seq;
2750 msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;
2751 msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
2752
2753 if (mp_opt->mp_capable) {
2754 msk->can_ack = true;
2755 msk->remote_key = mp_opt->sndr_key;
2756 mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq);
2757 ack_seq++;
2758 WRITE_ONCE(msk->ack_seq, ack_seq);
2759 WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
2760 }
2761
2762 sock_reset_flag(nsk, SOCK_RCU_FREE);
2763 /* will be fully established after successful MPC subflow creation */
2764 inet_sk_state_store(nsk, TCP_SYN_RECV);
2765
2766 security_inet_csk_clone(nsk, req);
2767 bh_unlock_sock(nsk);
2768
2769 /* keep a single reference */
2770 __sock_put(nsk);
2771 return nsk;
2772 }
2773
mptcp_rcv_space_init(struct mptcp_sock * msk,const struct sock * ssk)2774 void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
2775 {
2776 const struct tcp_sock *tp = tcp_sk(ssk);
2777
2778 msk->rcvq_space.copied = 0;
2779 msk->rcvq_space.rtt_us = 0;
2780
2781 msk->rcvq_space.time = tp->tcp_mstamp;
2782
2783 /* initial rcv_space offering made to peer */
2784 msk->rcvq_space.space = min_t(u32, tp->rcv_wnd,
2785 TCP_INIT_CWND * tp->advmss);
2786 if (msk->rcvq_space.space == 0)
2787 msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;
2788
2789 WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
2790 }
2791
mptcp_accept(struct sock * sk,int flags,int * err,bool kern)2792 static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
2793 bool kern)
2794 {
2795 struct mptcp_sock *msk = mptcp_sk(sk);
2796 struct socket *listener;
2797 struct sock *newsk;
2798
2799 listener = __mptcp_nmpc_socket(msk);
2800 if (WARN_ON_ONCE(!listener)) {
2801 *err = -EINVAL;
2802 return NULL;
2803 }
2804
2805 pr_debug("msk=%p, listener=%p", msk, mptcp_subflow_ctx(listener->sk));
2806 newsk = inet_csk_accept(listener->sk, flags, err, kern);
2807 if (!newsk)
2808 return NULL;
2809
2810 pr_debug("msk=%p, subflow is mptcp=%d", msk, sk_is_mptcp(newsk));
2811 if (sk_is_mptcp(newsk)) {
2812 struct mptcp_subflow_context *subflow;
2813 struct sock *new_mptcp_sock;
2814
2815 subflow = mptcp_subflow_ctx(newsk);
2816 new_mptcp_sock = subflow->conn;
2817
2818 /* is_mptcp should be false if subflow->conn is missing, see
2819 * subflow_syn_recv_sock()
2820 */
2821 if (WARN_ON_ONCE(!new_mptcp_sock)) {
2822 tcp_sk(newsk)->is_mptcp = 0;
2823 return newsk;
2824 }
2825
2826 /* acquire the 2nd reference for the owning socket */
2827 sock_hold(new_mptcp_sock);
2828 newsk = new_mptcp_sock;
2829 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
2830 } else {
2831 MPTCP_INC_STATS(sock_net(sk),
2832 MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
2833 }
2834
2835 return newsk;
2836 }
2837
mptcp_destroy_common(struct mptcp_sock * msk)2838 void mptcp_destroy_common(struct mptcp_sock *msk)
2839 {
2840 struct sock *sk = (struct sock *)msk;
2841
2842 __mptcp_clear_xmit(sk);
2843
2844 /* move to sk_receive_queue, sk_stream_kill_queues will purge it */
2845 skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue);
2846
2847 skb_rbtree_purge(&msk->out_of_order_queue);
2848 mptcp_token_destroy(msk);
2849 mptcp_pm_free_anno_list(msk);
2850 }
2851
mptcp_destroy(struct sock * sk)2852 static void mptcp_destroy(struct sock *sk)
2853 {
2854 struct mptcp_sock *msk = mptcp_sk(sk);
2855
2856 mptcp_destroy_common(msk);
2857 sk_sockets_allocated_dec(sk);
2858 }
2859
__mptcp_data_acked(struct sock * sk)2860 void __mptcp_data_acked(struct sock *sk)
2861 {
2862 if (!sock_owned_by_user(sk))
2863 __mptcp_clean_una(sk);
2864 else
2865 set_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags);
2866
2867 if (mptcp_pending_data_fin_ack(sk))
2868 mptcp_schedule_work(sk);
2869 }
2870
__mptcp_check_push(struct sock * sk,struct sock * ssk)2871 void __mptcp_check_push(struct sock *sk, struct sock *ssk)
2872 {
2873 if (!mptcp_send_head(sk))
2874 return;
2875
2876 if (!sock_owned_by_user(sk)) {
2877 struct sock *xmit_ssk = mptcp_subflow_get_send(mptcp_sk(sk));
2878
2879 if (xmit_ssk == ssk)
2880 __mptcp_subflow_push_pending(sk, ssk);
2881 else if (xmit_ssk)
2882 mptcp_subflow_delegate(mptcp_subflow_ctx(xmit_ssk));
2883 } else {
2884 set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags);
2885 }
2886 }
2887
2888 /* processes deferred events and flush wmem */
mptcp_release_cb(struct sock * sk)2889 static void mptcp_release_cb(struct sock *sk)
2890 {
2891 for (;;) {
2892 unsigned long flags = 0;
2893
2894 if (test_and_clear_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags))
2895 flags |= BIT(MPTCP_PUSH_PENDING);
2896 if (test_and_clear_bit(MPTCP_RETRANSMIT, &mptcp_sk(sk)->flags))
2897 flags |= BIT(MPTCP_RETRANSMIT);
2898 if (!flags)
2899 break;
2900
2901 /* the following actions acquire the subflow socket lock
2902 *
2903 * 1) can't be invoked in atomic scope
2904 * 2) must avoid ABBA deadlock with msk socket spinlock: the RX
2905 * datapath acquires the msk socket spinlock while helding
2906 * the subflow socket lock
2907 */
2908
2909 spin_unlock_bh(&sk->sk_lock.slock);
2910 if (flags & BIT(MPTCP_PUSH_PENDING))
2911 __mptcp_push_pending(sk, 0);
2912 if (flags & BIT(MPTCP_RETRANSMIT))
2913 __mptcp_retrans(sk);
2914
2915 cond_resched();
2916 spin_lock_bh(&sk->sk_lock.slock);
2917 }
2918
2919 if (test_and_clear_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags))
2920 __mptcp_clean_una_wakeup(sk);
2921 if (test_and_clear_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->flags))
2922 __mptcp_error_report(sk);
2923
2924 /* push_pending may touch wmem_reserved, ensure we do the cleanup
2925 * later
2926 */
2927 __mptcp_update_wmem(sk);
2928 __mptcp_update_rmem(sk);
2929 }
2930
mptcp_subflow_process_delegated(struct sock * ssk)2931 void mptcp_subflow_process_delegated(struct sock *ssk)
2932 {
2933 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
2934 struct sock *sk = subflow->conn;
2935
2936 mptcp_data_lock(sk);
2937 if (!sock_owned_by_user(sk))
2938 __mptcp_subflow_push_pending(sk, ssk);
2939 else
2940 set_bit(MPTCP_PUSH_PENDING, &mptcp_sk(sk)->flags);
2941 mptcp_data_unlock(sk);
2942 mptcp_subflow_delegated_done(subflow);
2943 }
2944
mptcp_hash(struct sock * sk)2945 static int mptcp_hash(struct sock *sk)
2946 {
2947 /* should never be called,
2948 * we hash the TCP subflows not the master socket
2949 */
2950 WARN_ON_ONCE(1);
2951 return 0;
2952 }
2953
mptcp_unhash(struct sock * sk)2954 static void mptcp_unhash(struct sock *sk)
2955 {
2956 /* called from sk_common_release(), but nothing to do here */
2957 }
2958
mptcp_get_port(struct sock * sk,unsigned short snum)2959 static int mptcp_get_port(struct sock *sk, unsigned short snum)
2960 {
2961 struct mptcp_sock *msk = mptcp_sk(sk);
2962 struct socket *ssock;
2963
2964 ssock = __mptcp_nmpc_socket(msk);
2965 pr_debug("msk=%p, subflow=%p", msk, ssock);
2966 if (WARN_ON_ONCE(!ssock))
2967 return -EINVAL;
2968
2969 return inet_csk_get_port(ssock->sk, snum);
2970 }
2971
mptcp_finish_connect(struct sock * ssk)2972 void mptcp_finish_connect(struct sock *ssk)
2973 {
2974 struct mptcp_subflow_context *subflow;
2975 struct mptcp_sock *msk;
2976 struct sock *sk;
2977 u64 ack_seq;
2978
2979 subflow = mptcp_subflow_ctx(ssk);
2980 sk = subflow->conn;
2981 msk = mptcp_sk(sk);
2982
2983 pr_debug("msk=%p, token=%u", sk, subflow->token);
2984
2985 mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq);
2986 ack_seq++;
2987 subflow->map_seq = ack_seq;
2988 subflow->map_subflow_seq = 1;
2989
2990 /* the socket is not connected yet, no msk/subflow ops can access/race
2991 * accessing the field below
2992 */
2993 WRITE_ONCE(msk->remote_key, subflow->remote_key);
2994 WRITE_ONCE(msk->local_key, subflow->local_key);
2995 WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
2996 WRITE_ONCE(msk->snd_nxt, msk->write_seq);
2997 WRITE_ONCE(msk->ack_seq, ack_seq);
2998 WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
2999 WRITE_ONCE(msk->can_ack, 1);
3000 WRITE_ONCE(msk->snd_una, msk->write_seq);
3001
3002 mptcp_pm_new_connection(msk, ssk, 0);
3003
3004 mptcp_rcv_space_init(msk, ssk);
3005 }
3006
mptcp_sock_graft(struct sock * sk,struct socket * parent)3007 void mptcp_sock_graft(struct sock *sk, struct socket *parent)
3008 {
3009 write_lock_bh(&sk->sk_callback_lock);
3010 rcu_assign_pointer(sk->sk_wq, &parent->wq);
3011 sk_set_socket(sk, parent);
3012 sk->sk_uid = SOCK_INODE(parent)->i_uid;
3013 write_unlock_bh(&sk->sk_callback_lock);
3014 }
3015
mptcp_finish_join(struct sock * ssk)3016 bool mptcp_finish_join(struct sock *ssk)
3017 {
3018 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
3019 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
3020 struct sock *parent = (void *)msk;
3021 struct socket *parent_sock;
3022 bool ret;
3023
3024 pr_debug("msk=%p, subflow=%p", msk, subflow);
3025
3026 /* mptcp socket already closing? */
3027 if (!mptcp_is_fully_established(parent)) {
3028 subflow->reset_reason = MPTCP_RST_EMPTCP;
3029 return false;
3030 }
3031
3032 if (!msk->pm.server_side)
3033 goto out;
3034
3035 if (!mptcp_pm_allow_new_subflow(msk)) {
3036 subflow->reset_reason = MPTCP_RST_EPROHIBIT;
3037 return false;
3038 }
3039
3040 /* active connections are already on conn_list, and we can't acquire
3041 * msk lock here.
3042 * use the join list lock as synchronization point and double-check
3043 * msk status to avoid racing with __mptcp_destroy_sock()
3044 */
3045 spin_lock_bh(&msk->join_list_lock);
3046 ret = inet_sk_state_load(parent) == TCP_ESTABLISHED;
3047 if (ret && !WARN_ON_ONCE(!list_empty(&subflow->node))) {
3048 list_add_tail(&subflow->node, &msk->join_list);
3049 sock_hold(ssk);
3050 }
3051 spin_unlock_bh(&msk->join_list_lock);
3052 if (!ret) {
3053 subflow->reset_reason = MPTCP_RST_EPROHIBIT;
3054 return false;
3055 }
3056
3057 /* attach to msk socket only after we are sure he will deal with us
3058 * at close time
3059 */
3060 parent_sock = READ_ONCE(parent->sk_socket);
3061 if (parent_sock && !ssk->sk_socket)
3062 mptcp_sock_graft(ssk, parent_sock);
3063 subflow->map_seq = READ_ONCE(msk->ack_seq);
3064 out:
3065 mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC);
3066 return true;
3067 }
3068
mptcp_shutdown(struct sock * sk,int how)3069 static void mptcp_shutdown(struct sock *sk, int how)
3070 {
3071 pr_debug("sk=%p, how=%d", sk, how);
3072
3073 if ((how & SEND_SHUTDOWN) && mptcp_close_state(sk))
3074 __mptcp_wr_shutdown(sk);
3075 }
3076
3077 static struct proto mptcp_prot = {
3078 .name = "MPTCP",
3079 .owner = THIS_MODULE,
3080 .init = mptcp_init_sock,
3081 .disconnect = mptcp_disconnect,
3082 .close = mptcp_close,
3083 .accept = mptcp_accept,
3084 .setsockopt = mptcp_setsockopt,
3085 .getsockopt = mptcp_getsockopt,
3086 .shutdown = mptcp_shutdown,
3087 .destroy = mptcp_destroy,
3088 .sendmsg = mptcp_sendmsg,
3089 .recvmsg = mptcp_recvmsg,
3090 .release_cb = mptcp_release_cb,
3091 .hash = mptcp_hash,
3092 .unhash = mptcp_unhash,
3093 .get_port = mptcp_get_port,
3094 .sockets_allocated = &mptcp_sockets_allocated,
3095 .memory_allocated = &tcp_memory_allocated,
3096 .memory_pressure = &tcp_memory_pressure,
3097 .sysctl_wmem_offset = offsetof(struct net, ipv4.sysctl_tcp_wmem),
3098 .sysctl_rmem_offset = offsetof(struct net, ipv4.sysctl_tcp_rmem),
3099 .sysctl_mem = sysctl_tcp_mem,
3100 .obj_size = sizeof(struct mptcp_sock),
3101 .slab_flags = SLAB_TYPESAFE_BY_RCU,
3102 .no_autobind = true,
3103 };
3104
mptcp_bind(struct socket * sock,struct sockaddr * uaddr,int addr_len)3105 static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
3106 {
3107 struct mptcp_sock *msk = mptcp_sk(sock->sk);
3108 struct socket *ssock;
3109 int err;
3110
3111 lock_sock(sock->sk);
3112 ssock = __mptcp_nmpc_socket(msk);
3113 if (!ssock) {
3114 err = -EINVAL;
3115 goto unlock;
3116 }
3117
3118 err = ssock->ops->bind(ssock, uaddr, addr_len);
3119 if (!err)
3120 mptcp_copy_inaddrs(sock->sk, ssock->sk);
3121
3122 unlock:
3123 release_sock(sock->sk);
3124 return err;
3125 }
3126
mptcp_subflow_early_fallback(struct mptcp_sock * msk,struct mptcp_subflow_context * subflow)3127 static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,
3128 struct mptcp_subflow_context *subflow)
3129 {
3130 subflow->request_mptcp = 0;
3131 __mptcp_do_fallback(msk);
3132 }
3133
mptcp_stream_connect(struct socket * sock,struct sockaddr * uaddr,int addr_len,int flags)3134 static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
3135 int addr_len, int flags)
3136 {
3137 struct mptcp_sock *msk = mptcp_sk(sock->sk);
3138 struct mptcp_subflow_context *subflow;
3139 struct socket *ssock;
3140 int err;
3141
3142 lock_sock(sock->sk);
3143 if (sock->state != SS_UNCONNECTED && msk->subflow) {
3144 /* pending connection or invalid state, let existing subflow
3145 * cope with that
3146 */
3147 ssock = msk->subflow;
3148 goto do_connect;
3149 }
3150
3151 ssock = __mptcp_nmpc_socket(msk);
3152 if (!ssock) {
3153 err = -EINVAL;
3154 goto unlock;
3155 }
3156
3157 mptcp_token_destroy(msk);
3158 inet_sk_state_store(sock->sk, TCP_SYN_SENT);
3159 subflow = mptcp_subflow_ctx(ssock->sk);
3160 #ifdef CONFIG_TCP_MD5SIG
3161 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
3162 * TCP option space.
3163 */
3164 if (rcu_access_pointer(tcp_sk(ssock->sk)->md5sig_info))
3165 mptcp_subflow_early_fallback(msk, subflow);
3166 #endif
3167 if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) {
3168 MPTCP_INC_STATS(sock_net(ssock->sk), MPTCP_MIB_TOKENFALLBACKINIT);
3169 mptcp_subflow_early_fallback(msk, subflow);
3170 }
3171 if (likely(!__mptcp_check_fallback(msk)))
3172 MPTCP_INC_STATS(sock_net(sock->sk), MPTCP_MIB_MPCAPABLEACTIVE);
3173
3174 do_connect:
3175 err = ssock->ops->connect(ssock, uaddr, addr_len, flags);
3176 sock->state = ssock->state;
3177
3178 /* on successful connect, the msk state will be moved to established by
3179 * subflow_finish_connect()
3180 */
3181 if (!err || err == -EINPROGRESS)
3182 mptcp_copy_inaddrs(sock->sk, ssock->sk);
3183 else
3184 inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));
3185
3186 unlock:
3187 release_sock(sock->sk);
3188 return err;
3189 }
3190
mptcp_listen(struct socket * sock,int backlog)3191 static int mptcp_listen(struct socket *sock, int backlog)
3192 {
3193 struct mptcp_sock *msk = mptcp_sk(sock->sk);
3194 struct socket *ssock;
3195 int err;
3196
3197 pr_debug("msk=%p", msk);
3198
3199 lock_sock(sock->sk);
3200 ssock = __mptcp_nmpc_socket(msk);
3201 if (!ssock) {
3202 err = -EINVAL;
3203 goto unlock;
3204 }
3205
3206 mptcp_token_destroy(msk);
3207 inet_sk_state_store(sock->sk, TCP_LISTEN);
3208 sock_set_flag(sock->sk, SOCK_RCU_FREE);
3209
3210 err = ssock->ops->listen(ssock, backlog);
3211 inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));
3212 if (!err)
3213 mptcp_copy_inaddrs(sock->sk, ssock->sk);
3214
3215 unlock:
3216 release_sock(sock->sk);
3217 return err;
3218 }
3219
mptcp_stream_accept(struct socket * sock,struct socket * newsock,int flags,bool kern)3220 static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
3221 int flags, bool kern)
3222 {
3223 struct mptcp_sock *msk = mptcp_sk(sock->sk);
3224 struct socket *ssock;
3225 int err;
3226
3227 pr_debug("msk=%p", msk);
3228
3229 lock_sock(sock->sk);
3230 if (sock->sk->sk_state != TCP_LISTEN)
3231 goto unlock_fail;
3232
3233 ssock = __mptcp_nmpc_socket(msk);
3234 if (!ssock)
3235 goto unlock_fail;
3236
3237 clear_bit(MPTCP_DATA_READY, &msk->flags);
3238 sock_hold(ssock->sk);
3239 release_sock(sock->sk);
3240
3241 err = ssock->ops->accept(sock, newsock, flags, kern);
3242 if (err == 0 && !mptcp_is_tcpsk(newsock->sk)) {
3243 struct mptcp_sock *msk = mptcp_sk(newsock->sk);
3244 struct mptcp_subflow_context *subflow;
3245 struct sock *newsk = newsock->sk;
3246
3247 lock_sock(newsk);
3248
3249 /* PM/worker can now acquire the first subflow socket
3250 * lock without racing with listener queue cleanup,
3251 * we can notify it, if needed.
3252 *
3253 * Even if remote has reset the initial subflow by now
3254 * the refcnt is still at least one.
3255 */
3256 subflow = mptcp_subflow_ctx(msk->first);
3257 list_add(&subflow->node, &msk->conn_list);
3258 sock_hold(msk->first);
3259 if (mptcp_is_fully_established(newsk))
3260 mptcp_pm_fully_established(msk, msk->first, GFP_KERNEL);
3261
3262 mptcp_copy_inaddrs(newsk, msk->first);
3263 mptcp_rcv_space_init(msk, msk->first);
3264 mptcp_propagate_sndbuf(newsk, msk->first);
3265
3266 /* set ssk->sk_socket of accept()ed flows to mptcp socket.
3267 * This is needed so NOSPACE flag can be set from tcp stack.
3268 */
3269 mptcp_flush_join_list(msk);
3270 mptcp_for_each_subflow(msk, subflow) {
3271 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3272
3273 if (!ssk->sk_socket)
3274 mptcp_sock_graft(ssk, newsock);
3275 }
3276 release_sock(newsk);
3277 }
3278
3279 if (inet_csk_listen_poll(ssock->sk))
3280 set_bit(MPTCP_DATA_READY, &msk->flags);
3281 sock_put(ssock->sk);
3282 return err;
3283
3284 unlock_fail:
3285 release_sock(sock->sk);
3286 return -EINVAL;
3287 }
3288
mptcp_check_readable(struct mptcp_sock * msk)3289 static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
3290 {
3291 return test_bit(MPTCP_DATA_READY, &msk->flags) ? EPOLLIN | EPOLLRDNORM :
3292 0;
3293 }
3294
mptcp_check_writeable(struct mptcp_sock * msk)3295 static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
3296 {
3297 struct sock *sk = (struct sock *)msk;
3298
3299 if (unlikely(sk->sk_shutdown & SEND_SHUTDOWN))
3300 return EPOLLOUT | EPOLLWRNORM;
3301
3302 if (sk_stream_is_writeable(sk))
3303 return EPOLLOUT | EPOLLWRNORM;
3304
3305 mptcp_set_nospace(sk);
3306 smp_mb__after_atomic(); /* msk->flags is changed by write_space cb */
3307 if (sk_stream_is_writeable(sk))
3308 return EPOLLOUT | EPOLLWRNORM;
3309
3310 return 0;
3311 }
3312
mptcp_poll(struct file * file,struct socket * sock,struct poll_table_struct * wait)3313 static __poll_t mptcp_poll(struct file *file, struct socket *sock,
3314 struct poll_table_struct *wait)
3315 {
3316 struct sock *sk = sock->sk;
3317 struct mptcp_sock *msk;
3318 __poll_t mask = 0;
3319 int state;
3320
3321 msk = mptcp_sk(sk);
3322 sock_poll_wait(file, sock, wait);
3323
3324 state = inet_sk_state_load(sk);
3325 pr_debug("msk=%p state=%d flags=%lx", msk, state, msk->flags);
3326 if (state == TCP_LISTEN)
3327 return mptcp_check_readable(msk);
3328
3329 if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
3330 mask |= mptcp_check_readable(msk);
3331 mask |= mptcp_check_writeable(msk);
3332 }
3333 if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
3334 mask |= EPOLLHUP;
3335 if (sk->sk_shutdown & RCV_SHUTDOWN)
3336 mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
3337
3338 /* This barrier is coupled with smp_wmb() in tcp_reset() */
3339 smp_rmb();
3340 if (sk->sk_err)
3341 mask |= EPOLLERR;
3342
3343 return mask;
3344 }
3345
3346 static const struct proto_ops mptcp_stream_ops = {
3347 .family = PF_INET,
3348 .owner = THIS_MODULE,
3349 .release = inet_release,
3350 .bind = mptcp_bind,
3351 .connect = mptcp_stream_connect,
3352 .socketpair = sock_no_socketpair,
3353 .accept = mptcp_stream_accept,
3354 .getname = inet_getname,
3355 .poll = mptcp_poll,
3356 .ioctl = inet_ioctl,
3357 .gettstamp = sock_gettstamp,
3358 .listen = mptcp_listen,
3359 .shutdown = inet_shutdown,
3360 .setsockopt = sock_common_setsockopt,
3361 .getsockopt = sock_common_getsockopt,
3362 .sendmsg = inet_sendmsg,
3363 .recvmsg = inet_recvmsg,
3364 .mmap = sock_no_mmap,
3365 .sendpage = inet_sendpage,
3366 };
3367
3368 static struct inet_protosw mptcp_protosw = {
3369 .type = SOCK_STREAM,
3370 .protocol = IPPROTO_MPTCP,
3371 .prot = &mptcp_prot,
3372 .ops = &mptcp_stream_ops,
3373 .flags = INET_PROTOSW_ICSK,
3374 };
3375
mptcp_napi_poll(struct napi_struct * napi,int budget)3376 static int mptcp_napi_poll(struct napi_struct *napi, int budget)
3377 {
3378 struct mptcp_delegated_action *delegated;
3379 struct mptcp_subflow_context *subflow;
3380 int work_done = 0;
3381
3382 delegated = container_of(napi, struct mptcp_delegated_action, napi);
3383 while ((subflow = mptcp_subflow_delegated_next(delegated)) != NULL) {
3384 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
3385
3386 bh_lock_sock_nested(ssk);
3387 if (!sock_owned_by_user(ssk) &&
3388 mptcp_subflow_has_delegated_action(subflow))
3389 mptcp_subflow_process_delegated(ssk);
3390 /* ... elsewhere tcp_release_cb_override already processed
3391 * the action or will do at next release_sock().
3392 * In both case must dequeue the subflow here - on the same
3393 * CPU that scheduled it.
3394 */
3395 bh_unlock_sock(ssk);
3396 sock_put(ssk);
3397
3398 if (++work_done == budget)
3399 return budget;
3400 }
3401
3402 /* always provide a 0 'work_done' argument, so that napi_complete_done
3403 * will not try accessing the NULL napi->dev ptr
3404 */
3405 napi_complete_done(napi, 0);
3406 return work_done;
3407 }
3408
mptcp_proto_init(void)3409 void __init mptcp_proto_init(void)
3410 {
3411 struct mptcp_delegated_action *delegated;
3412 int cpu;
3413
3414 mptcp_prot.h.hashinfo = tcp_prot.h.hashinfo;
3415
3416 if (percpu_counter_init(&mptcp_sockets_allocated, 0, GFP_KERNEL))
3417 panic("Failed to allocate MPTCP pcpu counter\n");
3418
3419 init_dummy_netdev(&mptcp_napi_dev);
3420 for_each_possible_cpu(cpu) {
3421 delegated = per_cpu_ptr(&mptcp_delegated_actions, cpu);
3422 INIT_LIST_HEAD(&delegated->head);
3423 netif_tx_napi_add(&mptcp_napi_dev, &delegated->napi, mptcp_napi_poll,
3424 NAPI_POLL_WEIGHT);
3425 napi_enable(&delegated->napi);
3426 }
3427
3428 mptcp_subflow_init();
3429 mptcp_pm_init();
3430 mptcp_token_init();
3431
3432 if (proto_register(&mptcp_prot, 1) != 0)
3433 panic("Failed to register MPTCP proto.\n");
3434
3435 inet_register_protosw(&mptcp_protosw);
3436
3437 BUILD_BUG_ON(sizeof(struct mptcp_skb_cb) > sizeof_field(struct sk_buff, cb));
3438 }
3439
3440 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
3441 static const struct proto_ops mptcp_v6_stream_ops = {
3442 .family = PF_INET6,
3443 .owner = THIS_MODULE,
3444 .release = inet6_release,
3445 .bind = mptcp_bind,
3446 .connect = mptcp_stream_connect,
3447 .socketpair = sock_no_socketpair,
3448 .accept = mptcp_stream_accept,
3449 .getname = inet6_getname,
3450 .poll = mptcp_poll,
3451 .ioctl = inet6_ioctl,
3452 .gettstamp = sock_gettstamp,
3453 .listen = mptcp_listen,
3454 .shutdown = inet_shutdown,
3455 .setsockopt = sock_common_setsockopt,
3456 .getsockopt = sock_common_getsockopt,
3457 .sendmsg = inet6_sendmsg,
3458 .recvmsg = inet6_recvmsg,
3459 .mmap = sock_no_mmap,
3460 .sendpage = inet_sendpage,
3461 #ifdef CONFIG_COMPAT
3462 .compat_ioctl = inet6_compat_ioctl,
3463 #endif
3464 };
3465
3466 static struct proto mptcp_v6_prot;
3467
mptcp_v6_destroy(struct sock * sk)3468 static void mptcp_v6_destroy(struct sock *sk)
3469 {
3470 mptcp_destroy(sk);
3471 inet6_destroy_sock(sk);
3472 }
3473
3474 static struct inet_protosw mptcp_v6_protosw = {
3475 .type = SOCK_STREAM,
3476 .protocol = IPPROTO_MPTCP,
3477 .prot = &mptcp_v6_prot,
3478 .ops = &mptcp_v6_stream_ops,
3479 .flags = INET_PROTOSW_ICSK,
3480 };
3481
mptcp_proto_v6_init(void)3482 int __init mptcp_proto_v6_init(void)
3483 {
3484 int err;
3485
3486 mptcp_v6_prot = mptcp_prot;
3487 strcpy(mptcp_v6_prot.name, "MPTCPv6");
3488 mptcp_v6_prot.slab = NULL;
3489 mptcp_v6_prot.destroy = mptcp_v6_destroy;
3490 mptcp_v6_prot.obj_size = sizeof(struct mptcp6_sock);
3491
3492 err = proto_register(&mptcp_v6_prot, 1);
3493 if (err)
3494 return err;
3495
3496 err = inet6_register_protosw(&mptcp_v6_protosw);
3497 if (err)
3498 proto_unregister(&mptcp_v6_prot);
3499
3500 return err;
3501 }
3502 #endif
3503