?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Merge tag 'hwmon-for-v6.13-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux.git] / net / mptcp / subflow.c
blobfd021cf8286eff9234b950a4d4c083ea7756eba3
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 <crypto/sha2.h>
13 #include <crypto/utils.h>
14 #include <net/sock.h>
15 #include <net/inet_common.h>
16 #include <net/inet_hashtables.h>
17 #include <net/protocol.h>
18 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
19 #include <net/ip6_route.h>
20 #include <net/transp_v6.h>
21 #endif
22 #include <net/mptcp.h>
23
24 #include "protocol.h"
25 #include "mib.h"
26
27 #include <trace/events/mptcp.h>
28 #include <trace/events/sock.h>
29
30 static void mptcp_subflow_ops_undo_override(struct sock *ssk);
31
32 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
33 enum linux_mptcp_mib_field field)
34 {
35 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
36 }
37
38 static void subflow_req_destructor(struct request_sock *req)
39 {
40 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
41
42 pr_debug("subflow_req=%p\n", subflow_req);
43
44 if (subflow_req->msk)
45 sock_put((struct sock *)subflow_req->msk);
46
47 mptcp_token_destroy_request(req);
48 }
49
50 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
51 void *hmac)
52 {
53 u8 msg[8];
54
55 put_unaligned_be32(nonce1, &msg[0]);
56 put_unaligned_be32(nonce2, &msg[4]);
57
58 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
59 }
60
61 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
62 {
63 return mptcp_is_fully_established((void *)msk) &&
64 ((mptcp_pm_is_userspace(msk) &&
65 mptcp_userspace_pm_active(msk)) ||
66 READ_ONCE(msk->pm.accept_subflow));
67 }
68
69 /* validate received token and create truncated hmac and nonce for SYN-ACK */
70 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
71 {
72 struct mptcp_sock *msk = subflow_req->msk;
73 u8 hmac[SHA256_DIGEST_SIZE];
74
75 get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
76
77 subflow_generate_hmac(READ_ONCE(msk->local_key),
78 READ_ONCE(msk->remote_key),
79 subflow_req->local_nonce,
80 subflow_req->remote_nonce, hmac);
81
82 subflow_req->thmac = get_unaligned_be64(hmac);
83 }
84
85 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
86 {
87 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
88 struct mptcp_sock *msk;
89 int local_id;
90
91 msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
92 if (!msk) {
93 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
94 return NULL;
95 }
96
97 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
98 if (local_id < 0) {
99 sock_put((struct sock *)msk);
100 return NULL;
101 }
102 subflow_req->local_id = local_id;
103 subflow_req->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)req);
104
105 return msk;
106 }
107
108 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
109 {
110 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
111
112 subflow_req->mp_capable = 0;
113 subflow_req->mp_join = 0;
114 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
115 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
116 subflow_req->msk = NULL;
117 mptcp_token_init_request(req);
118 }
119
120 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
121 {
122 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
123 }
124
125 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
126 {
127 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
128
129 if (mpext) {
130 memset(mpext, 0, sizeof(*mpext));
131 mpext->reset_reason = reason;
132 }
133 }
134
135 static int subflow_reset_req_endp(struct request_sock *req, struct sk_buff *skb)
136 {
137 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEENDPATTEMPT);
138 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
139 return -EPERM;
140 }
141
142 /* Init mptcp request socket.
143 *
144 * Returns an error code if a JOIN has failed and a TCP reset
145 * should be sent.
146 */
147 static int subflow_check_req(struct request_sock *req,
148 const struct sock *sk_listener,
149 struct sk_buff *skb)
150 {
151 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
152 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
153 struct mptcp_options_received mp_opt;
154 bool opt_mp_capable, opt_mp_join;
155
156 pr_debug("subflow_req=%p, listener=%p\n", subflow_req, listener);
157
158 #ifdef CONFIG_TCP_MD5SIG
159 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
160 * TCP option space.
161 */
162 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) {
163 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
164 return -EINVAL;
165 }
166 #endif
167
168 mptcp_get_options(skb, &mp_opt);
169
170 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN);
171 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN);
172 if (opt_mp_capable) {
173 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
174
175 if (unlikely(listener->pm_listener))
176 return subflow_reset_req_endp(req, skb);
177 if (opt_mp_join)
178 return 0;
179 } else if (opt_mp_join) {
180 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
181
182 if (mp_opt.backup)
183 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNBACKUPRX);
184 } else if (unlikely(listener->pm_listener)) {
185 return subflow_reset_req_endp(req, skb);
186 }
187
188 if (opt_mp_capable && listener->request_mptcp) {
189 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
190
191 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
192 again:
193 do {
194 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
195 } while (subflow_req->local_key == 0);
196
197 if (unlikely(req->syncookie)) {
198 mptcp_crypto_key_sha(subflow_req->local_key,
199 &subflow_req->token,
200 &subflow_req->idsn);
201 if (mptcp_token_exists(subflow_req->token)) {
202 if (retries-- > 0)
203 goto again;
204 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
205 } else {
206 subflow_req->mp_capable = 1;
207 }
208 return 0;
209 }
210
211 err = mptcp_token_new_request(req);
212 if (err == 0)
213 subflow_req->mp_capable = 1;
214 else if (retries-- > 0)
215 goto again;
216 else
217 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
218
219 } else if (opt_mp_join && listener->request_mptcp) {
220 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
221 subflow_req->mp_join = 1;
222 subflow_req->backup = mp_opt.backup;
223 subflow_req->remote_id = mp_opt.join_id;
224 subflow_req->token = mp_opt.token;
225 subflow_req->remote_nonce = mp_opt.nonce;
226 subflow_req->msk = subflow_token_join_request(req);
227
228 /* Can't fall back to TCP in this case. */
229 if (!subflow_req->msk) {
230 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
231 return -EPERM;
232 }
233
234 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
235 pr_debug("syn inet_sport=%d %d\n",
236 ntohs(inet_sk(sk_listener)->inet_sport),
237 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
238 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
239 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
240 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
241 return -EPERM;
242 }
243 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
244 }
245
246 subflow_req_create_thmac(subflow_req);
247
248 if (unlikely(req->syncookie)) {
249 if (!mptcp_can_accept_new_subflow(subflow_req->msk)) {
250 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
251 return -EPERM;
252 }
253
254 subflow_init_req_cookie_join_save(subflow_req, skb);
255 }
256
257 pr_debug("token=%u, remote_nonce=%u msk=%p\n", subflow_req->token,
258 subflow_req->remote_nonce, subflow_req->msk);
259 }
260
261 return 0;
262 }
263
264 int mptcp_subflow_init_cookie_req(struct request_sock *req,
265 const struct sock *sk_listener,
266 struct sk_buff *skb)
267 {
268 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
269 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
270 struct mptcp_options_received mp_opt;
271 bool opt_mp_capable, opt_mp_join;
272 int err;
273
274 subflow_init_req(req, sk_listener);
275 mptcp_get_options(skb, &mp_opt);
276
277 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK);
278 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK);
279 if (opt_mp_capable && opt_mp_join)
280 return -EINVAL;
281
282 if (opt_mp_capable && listener->request_mptcp) {
283 if (mp_opt.sndr_key == 0)
284 return -EINVAL;
285
286 subflow_req->local_key = mp_opt.rcvr_key;
287 err = mptcp_token_new_request(req);
288 if (err)
289 return err;
290
291 subflow_req->mp_capable = 1;
292 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
293 } else if (opt_mp_join && listener->request_mptcp) {
294 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
295 return -EINVAL;
296
297 subflow_req->mp_join = 1;
298 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
299 }
300
301 return 0;
302 }
303 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
304
305 static enum sk_rst_reason mptcp_get_rst_reason(const struct sk_buff *skb)
306 {
307 const struct mptcp_ext *mpext = mptcp_get_ext(skb);
308
309 if (!mpext)
310 return SK_RST_REASON_NOT_SPECIFIED;
311
312 return sk_rst_convert_mptcp_reason(mpext->reset_reason);
313 }
314
315 static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
316 struct sk_buff *skb,
317 struct flowi *fl,
318 struct request_sock *req,
319 u32 tw_isn)
320 {
321 struct dst_entry *dst;
322 int err;
323
324 tcp_rsk(req)->is_mptcp = 1;
325 subflow_init_req(req, sk);
326
327 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req, tw_isn);
328 if (!dst)
329 return NULL;
330
331 err = subflow_check_req(req, sk, skb);
332 if (err == 0)
333 return dst;
334
335 dst_release(dst);
336 if (!req->syncookie)
337 tcp_request_sock_ops.send_reset(sk, skb,
338 mptcp_get_rst_reason(skb));
339 return NULL;
340 }
341
342 static void subflow_prep_synack(const struct sock *sk, struct request_sock *req,
343 struct tcp_fastopen_cookie *foc,
344 enum tcp_synack_type synack_type)
345 {
346 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
347 struct inet_request_sock *ireq = inet_rsk(req);
348
349 /* clear tstamp_ok, as needed depending on cookie */
350 if (foc && foc->len > -1)
351 ireq->tstamp_ok = 0;
352
353 if (synack_type == TCP_SYNACK_FASTOPEN)
354 mptcp_fastopen_subflow_synack_set_params(subflow, req);
355 }
356
357 static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
358 struct flowi *fl,
359 struct request_sock *req,
360 struct tcp_fastopen_cookie *foc,
361 enum tcp_synack_type synack_type,
362 struct sk_buff *syn_skb)
363 {
364 subflow_prep_synack(sk, req, foc, synack_type);
365
366 return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc,
367 synack_type, syn_skb);
368 }
369
370 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
371 static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
372 struct flowi *fl,
373 struct request_sock *req,
374 struct tcp_fastopen_cookie *foc,
375 enum tcp_synack_type synack_type,
376 struct sk_buff *syn_skb)
377 {
378 subflow_prep_synack(sk, req, foc, synack_type);
379
380 return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc,
381 synack_type, syn_skb);
382 }
383
384 static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
385 struct sk_buff *skb,
386 struct flowi *fl,
387 struct request_sock *req,
388 u32 tw_isn)
389 {
390 struct dst_entry *dst;
391 int err;
392
393 tcp_rsk(req)->is_mptcp = 1;
394 subflow_init_req(req, sk);
395
396 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req, tw_isn);
397 if (!dst)
398 return NULL;
399
400 err = subflow_check_req(req, sk, skb);
401 if (err == 0)
402 return dst;
403
404 dst_release(dst);
405 if (!req->syncookie)
406 tcp6_request_sock_ops.send_reset(sk, skb,
407 mptcp_get_rst_reason(skb));
408 return NULL;
409 }
410 #endif
411
412 /* validate received truncated hmac and create hmac for third ACK */
413 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
414 {
415 u8 hmac[SHA256_DIGEST_SIZE];
416 u64 thmac;
417
418 subflow_generate_hmac(subflow->remote_key, subflow->local_key,
419 subflow->remote_nonce, subflow->local_nonce,
420 hmac);
421
422 thmac = get_unaligned_be64(hmac);
423 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
424 subflow, subflow->token, thmac, subflow->thmac);
425
426 return thmac == subflow->thmac;
427 }
428
429 void mptcp_subflow_reset(struct sock *ssk)
430 {
431 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
432 struct sock *sk = subflow->conn;
433
434 /* mptcp_mp_fail_no_response() can reach here on an already closed
435 * socket
436 */
437 if (ssk->sk_state == TCP_CLOSE)
438 return;
439
440 /* must hold: tcp_done() could drop last reference on parent */
441 sock_hold(sk);
442
443 mptcp_send_active_reset_reason(ssk);
444 tcp_done(ssk);
445 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
446 mptcp_schedule_work(sk);
447
448 sock_put(sk);
449 }
450
451 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
452 {
453 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
454 }
455
456 void __mptcp_sync_state(struct sock *sk, int state)
457 {
458 struct mptcp_subflow_context *subflow;
459 struct mptcp_sock *msk = mptcp_sk(sk);
460 struct sock *ssk = msk->first;
461
462 subflow = mptcp_subflow_ctx(ssk);
463 __mptcp_propagate_sndbuf(sk, ssk);
464 if (!msk->rcvspace_init)
465 mptcp_rcv_space_init(msk, ssk);
466
467 if (sk->sk_state == TCP_SYN_SENT) {
468 /* subflow->idsn is always available is TCP_SYN_SENT state,
469 * even for the FASTOPEN scenarios
470 */
471 WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
472 WRITE_ONCE(msk->snd_nxt, msk->write_seq);
473 mptcp_set_state(sk, state);
474 sk->sk_state_change(sk);
475 }
476 }
477
478 static void subflow_set_remote_key(struct mptcp_sock *msk,
479 struct mptcp_subflow_context *subflow,
480 const struct mptcp_options_received *mp_opt)
481 {
482 /* active MPC subflow will reach here multiple times:
483 * at subflow_finish_connect() time and at 4th ack time
484 */
485 if (subflow->remote_key_valid)
486 return;
487
488 subflow->remote_key_valid = 1;
489 subflow->remote_key = mp_opt->sndr_key;
490 mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
491 subflow->iasn++;
492
493 WRITE_ONCE(msk->remote_key, subflow->remote_key);
494 WRITE_ONCE(msk->ack_seq, subflow->iasn);
495 WRITE_ONCE(msk->can_ack, true);
496 atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
497 }
498
499 static void mptcp_propagate_state(struct sock *sk, struct sock *ssk,
500 struct mptcp_subflow_context *subflow,
501 const struct mptcp_options_received *mp_opt)
502 {
503 struct mptcp_sock *msk = mptcp_sk(sk);
504
505 mptcp_data_lock(sk);
506 if (mp_opt) {
507 /* Options are available only in the non fallback cases
508 * avoid updating rx path fields otherwise
509 */
510 WRITE_ONCE(msk->snd_una, subflow->idsn + 1);
511 WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd);
512 subflow_set_remote_key(msk, subflow, mp_opt);
513 }
514
515 if (!sock_owned_by_user(sk)) {
516 __mptcp_sync_state(sk, ssk->sk_state);
517 } else {
518 msk->pending_state = ssk->sk_state;
519 __set_bit(MPTCP_SYNC_STATE, &msk->cb_flags);
520 }
521 mptcp_data_unlock(sk);
522 }
523
524 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
525 {
526 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
527 struct mptcp_options_received mp_opt;
528 struct sock *parent = subflow->conn;
529 struct mptcp_sock *msk;
530
531 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
532
533 /* be sure no special action on any packet other than syn-ack */
534 if (subflow->conn_finished)
535 return;
536
537 msk = mptcp_sk(parent);
538 subflow->rel_write_seq = 1;
539 subflow->conn_finished = 1;
540 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
541 pr_debug("subflow=%p synack seq=%x\n", subflow, subflow->ssn_offset);
542
543 mptcp_get_options(skb, &mp_opt);
544 if (subflow->request_mptcp) {
545 if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) {
546 MPTCP_INC_STATS(sock_net(sk),
547 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
548 mptcp_do_fallback(sk);
549 pr_fallback(msk);
550 goto fallback;
551 }
552
553 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
554 WRITE_ONCE(msk->csum_enabled, true);
555 if (mp_opt.deny_join_id0)
556 WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
557 subflow->mp_capable = 1;
558 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
559 mptcp_finish_connect(sk);
560 mptcp_active_enable(parent);
561 mptcp_propagate_state(parent, sk, subflow, &mp_opt);
562 } else if (subflow->request_join) {
563 u8 hmac[SHA256_DIGEST_SIZE];
564
565 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) {
566 subflow->reset_reason = MPTCP_RST_EMPTCP;
567 goto do_reset;
568 }
569
570 subflow->backup = mp_opt.backup;
571 subflow->thmac = mp_opt.thmac;
572 subflow->remote_nonce = mp_opt.nonce;
573 WRITE_ONCE(subflow->remote_id, mp_opt.join_id);
574 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d\n",
575 subflow, subflow->thmac, subflow->remote_nonce,
576 subflow->backup);
577
578 if (!subflow_thmac_valid(subflow)) {
579 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
580 subflow->reset_reason = MPTCP_RST_EMPTCP;
581 goto do_reset;
582 }
583
584 if (!mptcp_finish_join(sk))
585 goto do_reset;
586
587 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
588 subflow->local_nonce,
589 subflow->remote_nonce,
590 hmac);
591 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
592
593 subflow->mp_join = 1;
594 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
595
596 if (subflow->backup)
597 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKBACKUPRX);
598
599 if (subflow_use_different_dport(msk, sk)) {
600 pr_debug("synack inet_dport=%d %d\n",
601 ntohs(inet_sk(sk)->inet_dport),
602 ntohs(inet_sk(parent)->inet_dport));
603 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
604 }
605 } else if (mptcp_check_fallback(sk)) {
606 /* It looks like MPTCP is blocked, while TCP is not */
607 if (subflow->mpc_drop)
608 mptcp_active_disable(parent);
609 fallback:
610 mptcp_propagate_state(parent, sk, subflow, NULL);
611 }
612 return;
613
614 do_reset:
615 subflow->reset_transient = 0;
616 mptcp_subflow_reset(sk);
617 }
618
619 static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
620 {
621 WARN_ON_ONCE(local_id < 0 || local_id > 255);
622 WRITE_ONCE(subflow->local_id, local_id);
623 }
624
625 static int subflow_chk_local_id(struct sock *sk)
626 {
627 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
628 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
629 int err;
630
631 if (likely(subflow->local_id >= 0))
632 return 0;
633
634 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
635 if (err < 0)
636 return err;
637
638 subflow_set_local_id(subflow, err);
639 subflow->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)sk);
640
641 return 0;
642 }
643
644 static int subflow_rebuild_header(struct sock *sk)
645 {
646 int err = subflow_chk_local_id(sk);
647
648 if (unlikely(err < 0))
649 return err;
650
651 return inet_sk_rebuild_header(sk);
652 }
653
654 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
655 static int subflow_v6_rebuild_header(struct sock *sk)
656 {
657 int err = subflow_chk_local_id(sk);
658
659 if (unlikely(err < 0))
660 return err;
661
662 return inet6_sk_rebuild_header(sk);
663 }
664 #endif
665
666 static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
667 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
668
669 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
670 {
671 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
672
673 pr_debug("subflow=%p\n", subflow);
674
675 /* Never answer to SYNs sent to broadcast or multicast */
676 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
677 goto drop;
678
679 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
680 &subflow_request_sock_ipv4_ops,
681 sk, skb);
682 drop:
683 tcp_listendrop(sk);
684 return 0;
685 }
686
687 static void subflow_v4_req_destructor(struct request_sock *req)
688 {
689 subflow_req_destructor(req);
690 tcp_request_sock_ops.destructor(req);
691 }
692
693 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
694 static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
695 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
696 static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
697 static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
698 static struct proto tcpv6_prot_override __ro_after_init;
699
700 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
701 {
702 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
703
704 pr_debug("subflow=%p\n", subflow);
705
706 if (skb->protocol == htons(ETH_P_IP))
707 return subflow_v4_conn_request(sk, skb);
708
709 if (!ipv6_unicast_destination(skb))
710 goto drop;
711
712 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
713 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
714 return 0;
715 }
716
717 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
718 &subflow_request_sock_ipv6_ops, sk, skb);
719
720 drop:
721 tcp_listendrop(sk);
722 return 0; /* don't send reset */
723 }
724
725 static void subflow_v6_req_destructor(struct request_sock *req)
726 {
727 subflow_req_destructor(req);
728 tcp6_request_sock_ops.destructor(req);
729 }
730 #endif
731
732 struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
733 struct sock *sk_listener,
734 bool attach_listener)
735 {
736 if (ops->family == AF_INET)
737 ops = &mptcp_subflow_v4_request_sock_ops;
738 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
739 else if (ops->family == AF_INET6)
740 ops = &mptcp_subflow_v6_request_sock_ops;
741 #endif
742
743 return inet_reqsk_alloc(ops, sk_listener, attach_listener);
744 }
745 EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
746
747 /* validate hmac received in third ACK */
748 static bool subflow_hmac_valid(const struct request_sock *req,
749 const struct mptcp_options_received *mp_opt)
750 {
751 const struct mptcp_subflow_request_sock *subflow_req;
752 u8 hmac[SHA256_DIGEST_SIZE];
753 struct mptcp_sock *msk;
754
755 subflow_req = mptcp_subflow_rsk(req);
756 msk = subflow_req->msk;
757 if (!msk)
758 return false;
759
760 subflow_generate_hmac(READ_ONCE(msk->remote_key),
761 READ_ONCE(msk->local_key),
762 subflow_req->remote_nonce,
763 subflow_req->local_nonce, hmac);
764
765 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
766 }
767
768 static void subflow_ulp_fallback(struct sock *sk,
769 struct mptcp_subflow_context *old_ctx)
770 {
771 struct inet_connection_sock *icsk = inet_csk(sk);
772
773 mptcp_subflow_tcp_fallback(sk, old_ctx);
774 icsk->icsk_ulp_ops = NULL;
775 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
776 tcp_sk(sk)->is_mptcp = 0;
777
778 mptcp_subflow_ops_undo_override(sk);
779 }
780
781 void mptcp_subflow_drop_ctx(struct sock *ssk)
782 {
783 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
784
785 if (!ctx)
786 return;
787
788 list_del(&mptcp_subflow_ctx(ssk)->node);
789 if (inet_csk(ssk)->icsk_ulp_ops) {
790 subflow_ulp_fallback(ssk, ctx);
791 if (ctx->conn)
792 sock_put(ctx->conn);
793 }
794
795 kfree_rcu(ctx, rcu);
796 }
797
798 void __mptcp_subflow_fully_established(struct mptcp_sock *msk,
799 struct mptcp_subflow_context *subflow,
800 const struct mptcp_options_received *mp_opt)
801 {
802 subflow_set_remote_key(msk, subflow, mp_opt);
803 WRITE_ONCE(subflow->fully_established, true);
804 WRITE_ONCE(msk->fully_established, true);
805
806 if (subflow->is_mptfo)
807 __mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt);
808 }
809
810 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
811 struct sk_buff *skb,
812 struct request_sock *req,
813 struct dst_entry *dst,
814 struct request_sock *req_unhash,
815 bool *own_req)
816 {
817 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
818 struct mptcp_subflow_request_sock *subflow_req;
819 struct mptcp_options_received mp_opt;
820 bool fallback, fallback_is_fatal;
821 enum sk_rst_reason reason;
822 struct mptcp_sock *owner;
823 struct sock *child;
824
825 pr_debug("listener=%p, req=%p, conn=%p\n", listener, req, listener->conn);
826
827 /* After child creation we must look for MPC even when options
828 * are not parsed
829 */
830 mp_opt.suboptions = 0;
831
832 /* hopefully temporary handling for MP_JOIN+syncookie */
833 subflow_req = mptcp_subflow_rsk(req);
834 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
835 fallback = !tcp_rsk(req)->is_mptcp;
836 if (fallback)
837 goto create_child;
838
839 /* if the sk is MP_CAPABLE, we try to fetch the client key */
840 if (subflow_req->mp_capable) {
841 /* we can receive and accept an in-window, out-of-order pkt,
842 * which may not carry the MP_CAPABLE opt even on mptcp enabled
843 * paths: always try to extract the peer key, and fallback
844 * for packets missing it.
845 * Even OoO DSS packets coming legitly after dropped or
846 * reordered MPC will cause fallback, but we don't have other
847 * options.
848 */
849 mptcp_get_options(skb, &mp_opt);
850 if (!(mp_opt.suboptions &
851 (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK)))
852 fallback = true;
853
854 } else if (subflow_req->mp_join) {
855 mptcp_get_options(skb, &mp_opt);
856 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) ||
857 !subflow_hmac_valid(req, &mp_opt) ||
858 !mptcp_can_accept_new_subflow(subflow_req->msk)) {
859 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
860 fallback = true;
861 }
862 }
863
864 create_child:
865 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
866 req_unhash, own_req);
867
868 if (child && *own_req) {
869 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
870
871 tcp_rsk(req)->drop_req = false;
872
873 /* we need to fallback on ctx allocation failure and on pre-reqs
874 * checking above. In the latter scenario we additionally need
875 * to reset the context to non MPTCP status.
876 */
877 if (!ctx || fallback) {
878 if (fallback_is_fatal) {
879 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
880 goto dispose_child;
881 }
882 goto fallback;
883 }
884
885 /* ssk inherits options of listener sk */
886 ctx->setsockopt_seq = listener->setsockopt_seq;
887
888 if (ctx->mp_capable) {
889 ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req);
890 if (!ctx->conn)
891 goto fallback;
892
893 ctx->subflow_id = 1;
894 owner = mptcp_sk(ctx->conn);
895 mptcp_pm_new_connection(owner, child, 1);
896
897 /* with OoO packets we can reach here without ingress
898 * mpc option
899 */
900 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) {
901 mptcp_pm_fully_established(owner, child);
902 ctx->pm_notified = 1;
903 }
904 } else if (ctx->mp_join) {
905 owner = subflow_req->msk;
906 if (!owner) {
907 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
908 goto dispose_child;
909 }
910
911 /* move the msk reference ownership to the subflow */
912 subflow_req->msk = NULL;
913 ctx->conn = (struct sock *)owner;
914
915 if (subflow_use_different_sport(owner, sk)) {
916 pr_debug("ack inet_sport=%d %d\n",
917 ntohs(inet_sk(sk)->inet_sport),
918 ntohs(inet_sk((struct sock *)owner)->inet_sport));
919 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
920 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
921 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
922 goto dispose_child;
923 }
924 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
925 }
926
927 if (!mptcp_finish_join(child)) {
928 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(child);
929
930 subflow_add_reset_reason(skb, subflow->reset_reason);
931 goto dispose_child;
932 }
933
934 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
935 tcp_rsk(req)->drop_req = true;
936 }
937 }
938
939 /* check for expected invariant - should never trigger, just help
940 * catching earlier subtle bugs
941 */
942 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
943 (!mptcp_subflow_ctx(child) ||
944 !mptcp_subflow_ctx(child)->conn));
945 return child;
946
947 dispose_child:
948 mptcp_subflow_drop_ctx(child);
949 tcp_rsk(req)->drop_req = true;
950 inet_csk_prepare_for_destroy_sock(child);
951 tcp_done(child);
952 reason = mptcp_get_rst_reason(skb);
953 req->rsk_ops->send_reset(sk, skb, reason);
954
955 /* The last child reference will be released by the caller */
956 return child;
957
958 fallback:
959 if (fallback)
960 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
961 mptcp_subflow_drop_ctx(child);
962 return child;
963 }
964
965 static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
966 static struct proto tcp_prot_override __ro_after_init;
967
968 enum mapping_status {
969 MAPPING_OK,
970 MAPPING_INVALID,
971 MAPPING_EMPTY,
972 MAPPING_DATA_FIN,
973 MAPPING_DUMMY,
974 MAPPING_BAD_CSUM,
975 MAPPING_NODSS
976 };
977
978 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
979 {
980 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d\n",
981 ssn, subflow->map_subflow_seq, subflow->map_data_len);
982 }
983
984 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
985 {
986 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
987 unsigned int skb_consumed;
988
989 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
990 if (unlikely(skb_consumed >= skb->len)) {
991 DEBUG_NET_WARN_ON_ONCE(1);
992 return true;
993 }
994
995 return skb->len - skb_consumed <= subflow->map_data_len -
996 mptcp_subflow_get_map_offset(subflow);
997 }
998
999 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
1000 {
1001 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1002 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1003
1004 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
1005 /* Mapping covers data later in the subflow stream,
1006 * currently unsupported.
1007 */
1008 dbg_bad_map(subflow, ssn);
1009 return false;
1010 }
1011 if (unlikely(!before(ssn, subflow->map_subflow_seq +
1012 subflow->map_data_len))) {
1013 /* Mapping does covers past subflow data, invalid */
1014 dbg_bad_map(subflow, ssn);
1015 return false;
1016 }
1017 return true;
1018 }
1019
1020 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
1021 bool csum_reqd)
1022 {
1023 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1024 u32 offset, seq, delta;
1025 __sum16 csum;
1026 int len;
1027
1028 if (!csum_reqd)
1029 return MAPPING_OK;
1030
1031 /* mapping already validated on previous traversal */
1032 if (subflow->map_csum_len == subflow->map_data_len)
1033 return MAPPING_OK;
1034
1035 /* traverse the receive queue, ensuring it contains a full
1036 * DSS mapping and accumulating the related csum.
1037 * Preserve the accoumlate csum across multiple calls, to compute
1038 * the csum only once
1039 */
1040 delta = subflow->map_data_len - subflow->map_csum_len;
1041 for (;;) {
1042 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
1043 offset = seq - TCP_SKB_CB(skb)->seq;
1044
1045 /* if the current skb has not been accounted yet, csum its contents
1046 * up to the amount covered by the current DSS
1047 */
1048 if (offset < skb->len) {
1049 __wsum csum;
1050
1051 len = min(skb->len - offset, delta);
1052 csum = skb_checksum(skb, offset, len, 0);
1053 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
1054 subflow->map_csum_len);
1055
1056 delta -= len;
1057 subflow->map_csum_len += len;
1058 }
1059 if (delta == 0)
1060 break;
1061
1062 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
1063 /* if this subflow is closed, the partial mapping
1064 * will be never completed; flush the pending skbs, so
1065 * that subflow_sched_work_if_closed() can kick in
1066 */
1067 if (unlikely(ssk->sk_state == TCP_CLOSE))
1068 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1069 sk_eat_skb(ssk, skb);
1070
1071 /* not enough data to validate the csum */
1072 return MAPPING_EMPTY;
1073 }
1074
1075 /* the DSS mapping for next skbs will be validated later,
1076 * when a get_mapping_status call will process such skb
1077 */
1078 skb = skb->next;
1079 }
1080
1081 /* note that 'map_data_len' accounts only for the carried data, does
1082 * not include the eventual seq increment due to the data fin,
1083 * while the pseudo header requires the original DSS data len,
1084 * including that
1085 */
1086 csum = __mptcp_make_csum(subflow->map_seq,
1087 subflow->map_subflow_seq,
1088 subflow->map_data_len + subflow->map_data_fin,
1089 subflow->map_data_csum);
1090 if (unlikely(csum)) {
1091 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
1092 return MAPPING_BAD_CSUM;
1093 }
1094
1095 subflow->valid_csum_seen = 1;
1096 return MAPPING_OK;
1097 }
1098
1099 static enum mapping_status get_mapping_status(struct sock *ssk,
1100 struct mptcp_sock *msk)
1101 {
1102 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1103 bool csum_reqd = READ_ONCE(msk->csum_enabled);
1104 struct mptcp_ext *mpext;
1105 struct sk_buff *skb;
1106 u16 data_len;
1107 u64 map_seq;
1108
1109 skb = skb_peek(&ssk->sk_receive_queue);
1110 if (!skb)
1111 return MAPPING_EMPTY;
1112
1113 if (mptcp_check_fallback(ssk))
1114 return MAPPING_DUMMY;
1115
1116 mpext = mptcp_get_ext(skb);
1117 if (!mpext || !mpext->use_map) {
1118 if (!subflow->map_valid && !skb->len) {
1119 /* the TCP stack deliver 0 len FIN pkt to the receive
1120 * queue, that is the only 0len pkts ever expected here,
1121 * and we can admit no mapping only for 0 len pkts
1122 */
1123 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
1124 WARN_ONCE(1, "0len seq %d:%d flags %x",
1125 TCP_SKB_CB(skb)->seq,
1126 TCP_SKB_CB(skb)->end_seq,
1127 TCP_SKB_CB(skb)->tcp_flags);
1128 sk_eat_skb(ssk, skb);
1129 return MAPPING_EMPTY;
1130 }
1131
1132 /* If the required DSS has likely been dropped by a middlebox */
1133 if (!subflow->map_valid)
1134 return MAPPING_NODSS;
1135
1136 goto validate_seq;
1137 }
1138
1139 trace_get_mapping_status(mpext);
1140
1141 data_len = mpext->data_len;
1142 if (data_len == 0) {
1143 pr_debug("infinite mapping received\n");
1144 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
1145 subflow->map_data_len = 0;
1146 return MAPPING_INVALID;
1147 }
1148
1149 if (mpext->data_fin == 1) {
1150 u64 data_fin_seq;
1151
1152 if (data_len == 1) {
1153 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
1154 mpext->dsn64);
1155 pr_debug("DATA_FIN with no payload seq=%llu\n", mpext->data_seq);
1156 if (subflow->map_valid) {
1157 /* A DATA_FIN might arrive in a DSS
1158 * option before the previous mapping
1159 * has been fully consumed. Continue
1160 * handling the existing mapping.
1161 */
1162 skb_ext_del(skb, SKB_EXT_MPTCP);
1163 return MAPPING_OK;
1164 }
1165
1166 if (updated)
1167 mptcp_schedule_work((struct sock *)msk);
1168
1169 return MAPPING_DATA_FIN;
1170 }
1171
1172 data_fin_seq = mpext->data_seq + data_len - 1;
1173
1174 /* If mpext->data_seq is a 32-bit value, data_fin_seq must also
1175 * be limited to 32 bits.
1176 */
1177 if (!mpext->dsn64)
1178 data_fin_seq &= GENMASK_ULL(31, 0);
1179
1180 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1181 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d\n",
1182 data_fin_seq, mpext->dsn64);
1183
1184 /* Adjust for DATA_FIN using 1 byte of sequence space */
1185 data_len--;
1186 }
1187
1188 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1189 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1190
1191 if (subflow->map_valid) {
1192 /* Allow replacing only with an identical map */
1193 if (subflow->map_seq == map_seq &&
1194 subflow->map_subflow_seq == mpext->subflow_seq &&
1195 subflow->map_data_len == data_len &&
1196 subflow->map_csum_reqd == mpext->csum_reqd) {
1197 skb_ext_del(skb, SKB_EXT_MPTCP);
1198 goto validate_csum;
1199 }
1200
1201 /* If this skb data are fully covered by the current mapping,
1202 * the new map would need caching, which is not supported
1203 */
1204 if (skb_is_fully_mapped(ssk, skb)) {
1205 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1206 return MAPPING_INVALID;
1207 }
1208
1209 /* will validate the next map after consuming the current one */
1210 goto validate_csum;
1211 }
1212
1213 subflow->map_seq = map_seq;
1214 subflow->map_subflow_seq = mpext->subflow_seq;
1215 subflow->map_data_len = data_len;
1216 subflow->map_valid = 1;
1217 subflow->map_data_fin = mpext->data_fin;
1218 subflow->mpc_map = mpext->mpc_map;
1219 subflow->map_csum_reqd = mpext->csum_reqd;
1220 subflow->map_csum_len = 0;
1221 subflow->map_data_csum = csum_unfold(mpext->csum);
1222
1223 /* Cfr RFC 8684 Section 3.3.0 */
1224 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1225 return MAPPING_INVALID;
1226
1227 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n",
1228 subflow->map_seq, subflow->map_subflow_seq,
1229 subflow->map_data_len, subflow->map_csum_reqd,
1230 subflow->map_data_csum);
1231
1232 validate_seq:
1233 /* we revalidate valid mapping on new skb, because we must ensure
1234 * the current skb is completely covered by the available mapping
1235 */
1236 if (!validate_mapping(ssk, skb)) {
1237 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1238 return MAPPING_INVALID;
1239 }
1240
1241 skb_ext_del(skb, SKB_EXT_MPTCP);
1242
1243 validate_csum:
1244 return validate_data_csum(ssk, skb, csum_reqd);
1245 }
1246
1247 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1248 u64 limit)
1249 {
1250 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1251 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1252 struct tcp_sock *tp = tcp_sk(ssk);
1253 u32 offset, incr, avail_len;
1254
1255 offset = tp->copied_seq - TCP_SKB_CB(skb)->seq;
1256 if (WARN_ON_ONCE(offset > skb->len))
1257 goto out;
1258
1259 avail_len = skb->len - offset;
1260 incr = limit >= avail_len ? avail_len + fin : limit;
1261
1262 pr_debug("discarding=%d len=%d offset=%d seq=%d\n", incr, skb->len,
1263 offset, subflow->map_subflow_seq);
1264 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1265 tcp_sk(ssk)->copied_seq += incr;
1266
1267 out:
1268 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1269 sk_eat_skb(ssk, skb);
1270 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1271 subflow->map_valid = 0;
1272 }
1273
1274 /* sched mptcp worker to remove the subflow if no more data is pending */
1275 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1276 {
1277 struct sock *sk = (struct sock *)msk;
1278
1279 if (likely(ssk->sk_state != TCP_CLOSE &&
1280 (ssk->sk_state != TCP_CLOSE_WAIT ||
1281 inet_sk_state_load(sk) != TCP_ESTABLISHED)))
1282 return;
1283
1284 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1285 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
1286 mptcp_schedule_work(sk);
1287 }
1288
1289 static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
1290 {
1291 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1292
1293 if (subflow->mp_join)
1294 return false;
1295 else if (READ_ONCE(msk->csum_enabled))
1296 return !subflow->valid_csum_seen;
1297 else
1298 return READ_ONCE(msk->allow_infinite_fallback);
1299 }
1300
1301 static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1302 {
1303 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1304 unsigned long fail_tout;
1305
1306 /* graceful failure can happen only on the MPC subflow */
1307 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1308 return;
1309
1310 /* since the close timeout take precedence on the fail one,
1311 * no need to start the latter when the first is already set
1312 */
1313 if (sock_flag((struct sock *)msk, SOCK_DEAD))
1314 return;
1315
1316 /* we don't need extreme accuracy here, use a zero fail_tout as special
1317 * value meaning no fail timeout at all;
1318 */
1319 fail_tout = jiffies + TCP_RTO_MAX;
1320 if (!fail_tout)
1321 fail_tout = 1;
1322 WRITE_ONCE(subflow->fail_tout, fail_tout);
1323 tcp_send_ack(ssk);
1324
1325 mptcp_reset_tout_timer(msk, subflow->fail_tout);
1326 }
1327
1328 static bool subflow_check_data_avail(struct sock *ssk)
1329 {
1330 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1331 enum mapping_status status;
1332 struct mptcp_sock *msk;
1333 struct sk_buff *skb;
1334
1335 if (!skb_peek(&ssk->sk_receive_queue))
1336 WRITE_ONCE(subflow->data_avail, false);
1337 if (subflow->data_avail)
1338 return true;
1339
1340 msk = mptcp_sk(subflow->conn);
1341 for (;;) {
1342 u64 ack_seq;
1343 u64 old_ack;
1344
1345 status = get_mapping_status(ssk, msk);
1346 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1347 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1348 status == MAPPING_BAD_CSUM || status == MAPPING_NODSS))
1349 goto fallback;
1350
1351 if (status != MAPPING_OK)
1352 goto no_data;
1353
1354 skb = skb_peek(&ssk->sk_receive_queue);
1355 if (WARN_ON_ONCE(!skb))
1356 goto no_data;
1357
1358 if (unlikely(!READ_ONCE(msk->can_ack)))
1359 goto fallback;
1360
1361 old_ack = READ_ONCE(msk->ack_seq);
1362 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1363 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx\n", old_ack,
1364 ack_seq);
1365 if (unlikely(before64(ack_seq, old_ack))) {
1366 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1367 continue;
1368 }
1369
1370 WRITE_ONCE(subflow->data_avail, true);
1371 break;
1372 }
1373 return true;
1374
1375 no_data:
1376 subflow_sched_work_if_closed(msk, ssk);
1377 return false;
1378
1379 fallback:
1380 if (!__mptcp_check_fallback(msk)) {
1381 /* RFC 8684 section 3.7. */
1382 if (status == MAPPING_BAD_CSUM &&
1383 (subflow->mp_join || subflow->valid_csum_seen)) {
1384 subflow->send_mp_fail = 1;
1385
1386 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1387 subflow->reset_transient = 0;
1388 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1389 goto reset;
1390 }
1391 mptcp_subflow_fail(msk, ssk);
1392 WRITE_ONCE(subflow->data_avail, true);
1393 return true;
1394 }
1395
1396 if (!subflow_can_fallback(subflow) && subflow->map_data_len) {
1397 /* fatal protocol error, close the socket.
1398 * subflow_error_report() will introduce the appropriate barriers
1399 */
1400 subflow->reset_transient = 0;
1401 subflow->reset_reason = status == MAPPING_NODSS ?
1402 MPTCP_RST_EMIDDLEBOX :
1403 MPTCP_RST_EMPTCP;
1404
1405 reset:
1406 WRITE_ONCE(ssk->sk_err, EBADMSG);
1407 tcp_set_state(ssk, TCP_CLOSE);
1408 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1409 sk_eat_skb(ssk, skb);
1410 mptcp_send_active_reset_reason(ssk);
1411 WRITE_ONCE(subflow->data_avail, false);
1412 return false;
1413 }
1414
1415 mptcp_do_fallback(ssk);
1416 }
1417
1418 skb = skb_peek(&ssk->sk_receive_queue);
1419 subflow->map_valid = 1;
1420 subflow->map_seq = READ_ONCE(msk->ack_seq);
1421 subflow->map_data_len = skb->len;
1422 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1423 WRITE_ONCE(subflow->data_avail, true);
1424 return true;
1425 }
1426
1427 bool mptcp_subflow_data_available(struct sock *sk)
1428 {
1429 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1430
1431 /* check if current mapping is still valid */
1432 if (subflow->map_valid &&
1433 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1434 subflow->map_valid = 0;
1435 WRITE_ONCE(subflow->data_avail, false);
1436
1437 pr_debug("Done with mapping: seq=%u data_len=%u\n",
1438 subflow->map_subflow_seq,
1439 subflow->map_data_len);
1440 }
1441
1442 return subflow_check_data_avail(sk);
1443 }
1444
1445 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1446 * not the ssk one.
1447 *
1448 * In mptcp, rwin is about the mptcp-level connection data.
1449 *
1450 * Data that is still on the ssk rx queue can thus be ignored,
1451 * as far as mptcp peer is concerned that data is still inflight.
1452 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1453 */
1454 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1455 {
1456 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1457 const struct sock *sk = subflow->conn;
1458
1459 *space = __mptcp_space(sk);
1460 *full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1461 }
1462
1463 static void subflow_error_report(struct sock *ssk)
1464 {
1465 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1466
1467 /* bail early if this is a no-op, so that we avoid introducing a
1468 * problematic lockdep dependency between TCP accept queue lock
1469 * and msk socket spinlock
1470 */
1471 if (!sk->sk_socket)
1472 return;
1473
1474 mptcp_data_lock(sk);
1475 if (!sock_owned_by_user(sk))
1476 __mptcp_error_report(sk);
1477 else
1478 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
1479 mptcp_data_unlock(sk);
1480 }
1481
1482 static void subflow_data_ready(struct sock *sk)
1483 {
1484 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1485 u16 state = 1 << inet_sk_state_load(sk);
1486 struct sock *parent = subflow->conn;
1487 struct mptcp_sock *msk;
1488
1489 trace_sk_data_ready(sk);
1490
1491 msk = mptcp_sk(parent);
1492 if (state & TCPF_LISTEN) {
1493 /* MPJ subflow are removed from accept queue before reaching here,
1494 * avoid stray wakeups
1495 */
1496 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1497 return;
1498
1499 parent->sk_data_ready(parent);
1500 return;
1501 }
1502
1503 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1504 !subflow->mp_join && !(state & TCPF_CLOSE));
1505
1506 if (mptcp_subflow_data_available(sk)) {
1507 mptcp_data_ready(parent, sk);
1508
1509 /* subflow-level lowat test are not relevant.
1510 * respect the msk-level threshold eventually mandating an immediate ack
1511 */
1512 if (mptcp_data_avail(msk) < parent->sk_rcvlowat &&
1513 (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss)
1514 inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
1515 } else if (unlikely(sk->sk_err)) {
1516 subflow_error_report(sk);
1517 }
1518 }
1519
1520 static void subflow_write_space(struct sock *ssk)
1521 {
1522 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1523
1524 mptcp_propagate_sndbuf(sk, ssk);
1525 mptcp_write_space(sk);
1526 }
1527
1528 static const struct inet_connection_sock_af_ops *
1529 subflow_default_af_ops(struct sock *sk)
1530 {
1531 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1532 if (sk->sk_family == AF_INET6)
1533 return &subflow_v6_specific;
1534 #endif
1535 return &subflow_specific;
1536 }
1537
1538 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1539 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1540 {
1541 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1542 struct inet_connection_sock *icsk = inet_csk(sk);
1543 const struct inet_connection_sock_af_ops *target;
1544
1545 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1546
1547 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d\n",
1548 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1549
1550 if (likely(icsk->icsk_af_ops == target))
1551 return;
1552
1553 subflow->icsk_af_ops = icsk->icsk_af_ops;
1554 icsk->icsk_af_ops = target;
1555 }
1556 #endif
1557
1558 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1559 struct sockaddr_storage *addr,
1560 unsigned short family)
1561 {
1562 memset(addr, 0, sizeof(*addr));
1563 addr->ss_family = family;
1564 if (addr->ss_family == AF_INET) {
1565 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1566
1567 if (info->family == AF_INET)
1568 in_addr->sin_addr = info->addr;
1569 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1570 else if (ipv6_addr_v4mapped(&info->addr6))
1571 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1572 #endif
1573 in_addr->sin_port = info->port;
1574 }
1575 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1576 else if (addr->ss_family == AF_INET6) {
1577 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1578
1579 if (info->family == AF_INET)
1580 ipv6_addr_set_v4mapped(info->addr.s_addr,
1581 &in6_addr->sin6_addr);
1582 else
1583 in6_addr->sin6_addr = info->addr6;
1584 in6_addr->sin6_port = info->port;
1585 }
1586 #endif
1587 }
1588
1589 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_pm_local *local,
1590 const struct mptcp_addr_info *remote)
1591 {
1592 struct mptcp_sock *msk = mptcp_sk(sk);
1593 struct mptcp_subflow_context *subflow;
1594 int local_id = local->addr.id;
1595 struct sockaddr_storage addr;
1596 int remote_id = remote->id;
1597 int err = -ENOTCONN;
1598 struct socket *sf;
1599 struct sock *ssk;
1600 u32 remote_token;
1601 int addrlen;
1602
1603 /* The userspace PM sent the request too early? */
1604 if (!mptcp_is_fully_established(sk))
1605 goto err_out;
1606
1607 err = mptcp_subflow_create_socket(sk, local->addr.family, &sf);
1608 if (err) {
1609 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCREATSKERR);
1610 pr_debug("msk=%p local=%d remote=%d create sock error: %d\n",
1611 msk, local_id, remote_id, err);
1612 goto err_out;
1613 }
1614
1615 ssk = sf->sk;
1616 subflow = mptcp_subflow_ctx(ssk);
1617 do {
1618 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1619 } while (!subflow->local_nonce);
1620
1621 /* if 'IPADDRANY', the ID will be set later, after the routing */
1622 if (local->addr.family == AF_INET) {
1623 if (!local->addr.addr.s_addr)
1624 local_id = -1;
1625 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1626 } else if (sk->sk_family == AF_INET6) {
1627 if (ipv6_addr_any(&local->addr.addr6))
1628 local_id = -1;
1629 #endif
1630 }
1631
1632 if (local_id >= 0)
1633 subflow_set_local_id(subflow, local_id);
1634
1635 subflow->remote_key_valid = 1;
1636 subflow->remote_key = READ_ONCE(msk->remote_key);
1637 subflow->local_key = READ_ONCE(msk->local_key);
1638 subflow->token = msk->token;
1639 mptcp_info2sockaddr(&local->addr, &addr, ssk->sk_family);
1640
1641 addrlen = sizeof(struct sockaddr_in);
1642 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1643 if (addr.ss_family == AF_INET6)
1644 addrlen = sizeof(struct sockaddr_in6);
1645 #endif
1646 ssk->sk_bound_dev_if = local->ifindex;
1647 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1648 if (err) {
1649 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXBINDERR);
1650 pr_debug("msk=%p local=%d remote=%d bind error: %d\n",
1651 msk, local_id, remote_id, err);
1652 goto failed;
1653 }
1654
1655 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1656 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d\n", msk,
1657 remote_token, local_id, remote_id);
1658 subflow->remote_token = remote_token;
1659 WRITE_ONCE(subflow->remote_id, remote_id);
1660 subflow->request_join = 1;
1661 subflow->request_bkup = !!(local->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1662 subflow->subflow_id = msk->subflow_id++;
1663 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1664
1665 sock_hold(ssk);
1666 list_add_tail(&subflow->node, &msk->conn_list);
1667 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1668 if (err && err != -EINPROGRESS) {
1669 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCONNECTERR);
1670 pr_debug("msk=%p local=%d remote=%d connect error: %d\n",
1671 msk, local_id, remote_id, err);
1672 goto failed_unlink;
1673 }
1674
1675 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTX);
1676
1677 /* discard the subflow socket */
1678 mptcp_sock_graft(ssk, sk->sk_socket);
1679 iput(SOCK_INODE(sf));
1680 WRITE_ONCE(msk->allow_infinite_fallback, false);
1681 mptcp_stop_tout_timer(sk);
1682 return 0;
1683
1684 failed_unlink:
1685 list_del(&subflow->node);
1686 sock_put(mptcp_subflow_tcp_sock(subflow));
1687
1688 failed:
1689 subflow->disposable = 1;
1690 sock_release(sf);
1691
1692 err_out:
1693 /* we account subflows before the creation, and this failures will not
1694 * be caught by sk_state_change()
1695 */
1696 mptcp_pm_close_subflow(msk);
1697 return err;
1698 }
1699
1700 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1701 {
1702 #ifdef CONFIG_SOCK_CGROUP_DATA
1703 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1704 *child_skcd = &child->sk_cgrp_data;
1705
1706 /* only the additional subflows created by kworkers have to be modified */
1707 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1708 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1709 #ifdef CONFIG_MEMCG
1710 struct mem_cgroup *memcg = parent->sk_memcg;
1711
1712 mem_cgroup_sk_free(child);
1713 if (memcg && css_tryget(&memcg->css))
1714 child->sk_memcg = memcg;
1715 #endif /* CONFIG_MEMCG */
1716
1717 cgroup_sk_free(child_skcd);
1718 *child_skcd = *parent_skcd;
1719 cgroup_sk_clone(child_skcd);
1720 }
1721 #endif /* CONFIG_SOCK_CGROUP_DATA */
1722 }
1723
1724 static void mptcp_subflow_ops_override(struct sock *ssk)
1725 {
1726 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1727 if (ssk->sk_prot == &tcpv6_prot)
1728 ssk->sk_prot = &tcpv6_prot_override;
1729 else
1730 #endif
1731 ssk->sk_prot = &tcp_prot_override;
1732 }
1733
1734 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1735 {
1736 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1737 if (ssk->sk_prot == &tcpv6_prot_override)
1738 ssk->sk_prot = &tcpv6_prot;
1739 else
1740 #endif
1741 ssk->sk_prot = &tcp_prot;
1742 }
1743
1744 int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1745 struct socket **new_sock)
1746 {
1747 struct mptcp_subflow_context *subflow;
1748 struct net *net = sock_net(sk);
1749 struct socket *sf;
1750 int err;
1751
1752 /* un-accepted server sockets can reach here - on bad configuration
1753 * bail early to avoid greater trouble later
1754 */
1755 if (unlikely(!sk->sk_socket))
1756 return -EINVAL;
1757
1758 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
1759 if (err)
1760 return err;
1761
1762 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
1763
1764 err = security_mptcp_add_subflow(sk, sf->sk);
1765 if (err)
1766 goto err_free;
1767
1768 /* the newly created socket has to be in the same cgroup as its parent */
1769 mptcp_attach_cgroup(sk, sf->sk);
1770
1771 /* kernel sockets do not by default acquire net ref, but TCP timer
1772 * needs it.
1773 * Update ns_tracker to current stack trace and refcounted tracker.
1774 */
1775 __netns_tracker_free(net, &sf->sk->ns_tracker, false);
1776 sf->sk->sk_net_refcnt = 1;
1777 get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL);
1778 sock_inuse_add(net, 1);
1779 err = tcp_set_ulp(sf->sk, "mptcp");
1780 if (err)
1781 goto err_free;
1782
1783 mptcp_sockopt_sync_locked(mptcp_sk(sk), sf->sk);
1784 release_sock(sf->sk);
1785
1786 /* the newly created socket really belongs to the owning MPTCP
1787 * socket, even if for additional subflows the allocation is performed
1788 * by a kernel workqueue. Adjust inode references, so that the
1789 * procfs/diag interfaces really show this one belonging to the correct
1790 * user.
1791 */
1792 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1793 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1794 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1795
1796 subflow = mptcp_subflow_ctx(sf->sk);
1797 pr_debug("subflow=%p\n", subflow);
1798
1799 *new_sock = sf;
1800 sock_hold(sk);
1801 subflow->conn = sk;
1802 mptcp_subflow_ops_override(sf->sk);
1803
1804 return 0;
1805
1806 err_free:
1807 release_sock(sf->sk);
1808 sock_release(sf);
1809 return err;
1810 }
1811
1812 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1813 gfp_t priority)
1814 {
1815 struct inet_connection_sock *icsk = inet_csk(sk);
1816 struct mptcp_subflow_context *ctx;
1817
1818 ctx = kzalloc(sizeof(*ctx), priority);
1819 if (!ctx)
1820 return NULL;
1821
1822 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1823 INIT_LIST_HEAD(&ctx->node);
1824 INIT_LIST_HEAD(&ctx->delegated_node);
1825
1826 pr_debug("subflow=%p\n", ctx);
1827
1828 ctx->tcp_sock = sk;
1829 WRITE_ONCE(ctx->local_id, -1);
1830
1831 return ctx;
1832 }
1833
1834 static void __subflow_state_change(struct sock *sk)
1835 {
1836 struct socket_wq *wq;
1837
1838 rcu_read_lock();
1839 wq = rcu_dereference(sk->sk_wq);
1840 if (skwq_has_sleeper(wq))
1841 wake_up_interruptible_all(&wq->wait);
1842 rcu_read_unlock();
1843 }
1844
1845 static bool subflow_is_done(const struct sock *sk)
1846 {
1847 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1848 }
1849
1850 static void subflow_state_change(struct sock *sk)
1851 {
1852 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1853 struct sock *parent = subflow->conn;
1854 struct mptcp_sock *msk;
1855
1856 __subflow_state_change(sk);
1857
1858 msk = mptcp_sk(parent);
1859 if (subflow_simultaneous_connect(sk)) {
1860 mptcp_do_fallback(sk);
1861 pr_fallback(msk);
1862 subflow->conn_finished = 1;
1863 mptcp_propagate_state(parent, sk, subflow, NULL);
1864 }
1865
1866 /* as recvmsg() does not acquire the subflow socket for ssk selection
1867 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1868 * the data available machinery here.
1869 */
1870 if (mptcp_subflow_data_available(sk))
1871 mptcp_data_ready(parent, sk);
1872 else if (unlikely(sk->sk_err))
1873 subflow_error_report(sk);
1874
1875 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1876
1877 /* when the fallback subflow closes the rx side, trigger a 'dummy'
1878 * ingress data fin, so that the msk state will follow along
1879 */
1880 if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
1881 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
1882 mptcp_schedule_work(parent);
1883 }
1884
1885 void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1886 {
1887 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
1888 struct request_sock *req, *head, *tail;
1889 struct mptcp_subflow_context *subflow;
1890 struct sock *sk, *ssk;
1891
1892 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
1893 * Splice the req list, so that accept() can not reach the pending ssk after
1894 * the listener socket is released below.
1895 */
1896 spin_lock_bh(&queue->rskq_lock);
1897 head = queue->rskq_accept_head;
1898 tail = queue->rskq_accept_tail;
1899 queue->rskq_accept_head = NULL;
1900 queue->rskq_accept_tail = NULL;
1901 spin_unlock_bh(&queue->rskq_lock);
1902
1903 if (!head)
1904 return;
1905
1906 /* can't acquire the msk socket lock under the subflow one,
1907 * or will cause ABBA deadlock
1908 */
1909 release_sock(listener_ssk);
1910
1911 for (req = head; req; req = req->dl_next) {
1912 ssk = req->sk;
1913 if (!sk_is_mptcp(ssk))
1914 continue;
1915
1916 subflow = mptcp_subflow_ctx(ssk);
1917 if (!subflow || !subflow->conn)
1918 continue;
1919
1920 sk = subflow->conn;
1921 sock_hold(sk);
1922
1923 lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1924 __mptcp_unaccepted_force_close(sk);
1925 release_sock(sk);
1926
1927 /* lockdep will report a false positive ABBA deadlock
1928 * between cancel_work_sync and the listener socket.
1929 * The involved locks belong to different sockets WRT
1930 * the existing AB chain.
1931 * Using a per socket key is problematic as key
1932 * deregistration requires process context and must be
1933 * performed at socket disposal time, in atomic
1934 * context.
1935 * Just tell lockdep to consider the listener socket
1936 * released here.
1937 */
1938 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1939 mptcp_cancel_work(sk);
1940 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
1941
1942 sock_put(sk);
1943 }
1944
1945 /* we are still under the listener msk socket lock */
1946 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
1947
1948 /* restore the listener queue, to let the TCP code clean it up */
1949 spin_lock_bh(&queue->rskq_lock);
1950 WARN_ON_ONCE(queue->rskq_accept_head);
1951 queue->rskq_accept_head = head;
1952 queue->rskq_accept_tail = tail;
1953 spin_unlock_bh(&queue->rskq_lock);
1954 }
1955
1956 static int subflow_ulp_init(struct sock *sk)
1957 {
1958 struct inet_connection_sock *icsk = inet_csk(sk);
1959 struct mptcp_subflow_context *ctx;
1960 struct tcp_sock *tp = tcp_sk(sk);
1961 int err = 0;
1962
1963 /* disallow attaching ULP to a socket unless it has been
1964 * created with sock_create_kern()
1965 */
1966 if (!sk->sk_kern_sock) {
1967 err = -EOPNOTSUPP;
1968 goto out;
1969 }
1970
1971 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1972 if (!ctx) {
1973 err = -ENOMEM;
1974 goto out;
1975 }
1976
1977 pr_debug("subflow=%p, family=%d\n", ctx, sk->sk_family);
1978
1979 tp->is_mptcp = 1;
1980 ctx->icsk_af_ops = icsk->icsk_af_ops;
1981 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1982 ctx->tcp_state_change = sk->sk_state_change;
1983 ctx->tcp_error_report = sk->sk_error_report;
1984
1985 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1986 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1987
1988 sk->sk_data_ready = subflow_data_ready;
1989 sk->sk_write_space = subflow_write_space;
1990 sk->sk_state_change = subflow_state_change;
1991 sk->sk_error_report = subflow_error_report;
1992 out:
1993 return err;
1994 }
1995
1996 static void subflow_ulp_release(struct sock *ssk)
1997 {
1998 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1999 bool release = true;
2000 struct sock *sk;
2001
2002 if (!ctx)
2003 return;
2004
2005 sk = ctx->conn;
2006 if (sk) {
2007 /* if the msk has been orphaned, keep the ctx
2008 * alive, will be freed by __mptcp_close_ssk(),
2009 * when the subflow is still unaccepted
2010 */
2011 release = ctx->disposable || list_empty(&ctx->node);
2012
2013 /* inet_child_forget() does not call sk_state_change(),
2014 * explicitly trigger the socket close machinery
2015 */
2016 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
2017 &mptcp_sk(sk)->flags))
2018 mptcp_schedule_work(sk);
2019 sock_put(sk);
2020 }
2021
2022 mptcp_subflow_ops_undo_override(ssk);
2023 if (release)
2024 kfree_rcu(ctx, rcu);
2025 }
2026
2027 static void subflow_ulp_clone(const struct request_sock *req,
2028 struct sock *newsk,
2029 const gfp_t priority)
2030 {
2031 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
2032 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
2033 struct mptcp_subflow_context *new_ctx;
2034
2035 if (!tcp_rsk(req)->is_mptcp ||
2036 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
2037 subflow_ulp_fallback(newsk, old_ctx);
2038 return;
2039 }
2040
2041 new_ctx = subflow_create_ctx(newsk, priority);
2042 if (!new_ctx) {
2043 subflow_ulp_fallback(newsk, old_ctx);
2044 return;
2045 }
2046
2047 new_ctx->conn_finished = 1;
2048 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
2049 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
2050 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
2051 new_ctx->rel_write_seq = 1;
2052
2053 if (subflow_req->mp_capable) {
2054 /* see comments in subflow_syn_recv_sock(), MPTCP connection
2055 * is fully established only after we receive the remote key
2056 */
2057 new_ctx->mp_capable = 1;
2058 new_ctx->local_key = subflow_req->local_key;
2059 new_ctx->token = subflow_req->token;
2060 new_ctx->ssn_offset = subflow_req->ssn_offset;
2061 new_ctx->idsn = subflow_req->idsn;
2062
2063 /* this is the first subflow, id is always 0 */
2064 subflow_set_local_id(new_ctx, 0);
2065 } else if (subflow_req->mp_join) {
2066 new_ctx->ssn_offset = subflow_req->ssn_offset;
2067 new_ctx->mp_join = 1;
2068 WRITE_ONCE(new_ctx->fully_established, true);
2069 new_ctx->remote_key_valid = 1;
2070 new_ctx->backup = subflow_req->backup;
2071 new_ctx->request_bkup = subflow_req->request_bkup;
2072 WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id);
2073 new_ctx->token = subflow_req->token;
2074 new_ctx->thmac = subflow_req->thmac;
2075
2076 /* the subflow req id is valid, fetched via subflow_check_req()
2077 * and subflow_token_join_request()
2078 */
2079 subflow_set_local_id(new_ctx, subflow_req->local_id);
2080 }
2081 }
2082
2083 static void tcp_release_cb_override(struct sock *ssk)
2084 {
2085 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
2086 long status;
2087
2088 /* process and clear all the pending actions, but leave the subflow into
2089 * the napi queue. To respect locking, only the same CPU that originated
2090 * the action can touch the list. mptcp_napi_poll will take care of it.
2091 */
2092 status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0);
2093 if (status)
2094 mptcp_subflow_process_delegated(ssk, status);
2095
2096 tcp_release_cb(ssk);
2097 }
2098
2099 static int tcp_abort_override(struct sock *ssk, int err)
2100 {
2101 /* closing a listener subflow requires a great deal of care.
2102 * keep it simple and just prevent such operation
2103 */
2104 if (inet_sk_state_load(ssk) == TCP_LISTEN)
2105 return -EINVAL;
2106
2107 return tcp_abort(ssk, err);
2108 }
2109
2110 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
2111 .name = "mptcp",
2112 .owner = THIS_MODULE,
2113 .init = subflow_ulp_init,
2114 .release = subflow_ulp_release,
2115 .clone = subflow_ulp_clone,
2116 };
2117
2118 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
2119 {
2120 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
2121
2122 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
2123 subflow_ops->obj_size, 0,
2124 SLAB_ACCOUNT |
2125 SLAB_TYPESAFE_BY_RCU,
2126 NULL);
2127 if (!subflow_ops->slab)
2128 return -ENOMEM;
2129
2130 return 0;
2131 }
2132
2133 void __init mptcp_subflow_init(void)
2134 {
2135 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
2136 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
2137 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
2138
2139 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
2140 panic("MPTCP: failed to init subflow v4 request sock ops\n");
2141
2142 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
2143 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
2144 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
2145
2146 subflow_specific = ipv4_specific;
2147 subflow_specific.conn_request = subflow_v4_conn_request;
2148 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
2149 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
2150 subflow_specific.rebuild_header = subflow_rebuild_header;
2151
2152 tcp_prot_override = tcp_prot;
2153 tcp_prot_override.release_cb = tcp_release_cb_override;
2154 tcp_prot_override.diag_destroy = tcp_abort_override;
2155
2156 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
2157 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock
2158 * structures for v4 and v6 have the same size. It should not changed in
2159 * the future but better to make sure to be warned if it is no longer
2160 * the case.
2161 */
2162 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
2163
2164 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
2165 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
2166 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
2167
2168 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
2169 panic("MPTCP: failed to init subflow v6 request sock ops\n");
2170
2171 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
2172 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
2173 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
2174
2175 subflow_v6_specific = ipv6_specific;
2176 subflow_v6_specific.conn_request = subflow_v6_conn_request;
2177 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
2178 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
2179 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
2180
2181 subflow_v6m_specific = subflow_v6_specific;
2182 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
2183 subflow_v6m_specific.send_check = ipv4_specific.send_check;
2184 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
2185 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
2186 subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
2187
2188 tcpv6_prot_override = tcpv6_prot;
2189 tcpv6_prot_override.release_cb = tcp_release_cb_override;
2190 tcpv6_prot_override.diag_destroy = tcp_abort_override;
2191 #endif
2192
2193 mptcp_diag_subflow_init(&subflow_ulp_ops);
2194
2195 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
2196 panic("MPTCP: failed to register subflows to ULP\n");
2197 }
Linux Kernel