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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
30static void mptcp_subflow_ops_undo_override(struct sock *ssk);
31
32static 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
38static 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
50static 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
61static 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 */
70static 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
85static 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
108static 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
120static 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
125static 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
135static 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 */
147static 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;
192again:
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
264int 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}
303EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
304
305static 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
315static 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
342static 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
357static 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)
371static 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
384static 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 */
413static 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
429void 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
451static 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
456void __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
478static 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
499static 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
524static 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);
609fallback:
610 mptcp_propagate_state(parent, sk, subflow, NULL);
611 }
612 return;
613
614do_reset:
615 subflow->reset_transient = 0;
616 mptcp_subflow_reset(sk);
617}
618
619static 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
625static 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
644static 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)
655static 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
666static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
667static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
668
669static 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);
682drop:
683 tcp_listendrop(sk);
684 return 0;
685}
686
687static 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)
694static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
695static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
696static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
697static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
698static struct proto tcpv6_prot_override __ro_after_init;
699
700static 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
720drop:
721 tcp_listendrop(sk);
722 return 0; /* don't send reset */
723}
724
725static 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
732struct 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}
745EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
746
747/* validate hmac received in third ACK */
748static 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
768static 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
781void 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
798void __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
810static 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
864create_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
947dispose_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
958fallback:
959 if (fallback)
960 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
961 mptcp_subflow_drop_ctx(child);
962 return child;
963}
964
965static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
966static struct proto tcp_prot_override __ro_after_init;
967
968enum 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
978static 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
984static 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
999static 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
1020static 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
1099static 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 return MAPPING_INVALID;
1146 }
1147
1148 if (mpext->data_fin == 1) {
1149 u64 data_fin_seq;
1150
1151 if (data_len == 1) {
1152 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
1153 mpext->dsn64);
1154 pr_debug("DATA_FIN with no payload seq=%llu\n", mpext->data_seq);
1155 if (subflow->map_valid) {
1156 /* A DATA_FIN might arrive in a DSS
1157 * option before the previous mapping
1158 * has been fully consumed. Continue
1159 * handling the existing mapping.
1160 */
1161 skb_ext_del(skb, SKB_EXT_MPTCP);
1162 return MAPPING_OK;
1163 }
1164
1165 if (updated)
1166 mptcp_schedule_work((struct sock *)msk);
1167
1168 return MAPPING_DATA_FIN;
1169 }
1170
1171 data_fin_seq = mpext->data_seq + data_len - 1;
1172
1173 /* If mpext->data_seq is a 32-bit value, data_fin_seq must also
1174 * be limited to 32 bits.
1175 */
1176 if (!mpext->dsn64)
1177 data_fin_seq &= GENMASK_ULL(31, 0);
1178
1179 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1180 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d\n",
1181 data_fin_seq, mpext->dsn64);
1182
1183 /* Adjust for DATA_FIN using 1 byte of sequence space */
1184 data_len--;
1185 }
1186
1187 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1188 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1189
1190 if (subflow->map_valid) {
1191 /* Allow replacing only with an identical map */
1192 if (subflow->map_seq == map_seq &&
1193 subflow->map_subflow_seq == mpext->subflow_seq &&
1194 subflow->map_data_len == data_len &&
1195 subflow->map_csum_reqd == mpext->csum_reqd) {
1196 skb_ext_del(skb, SKB_EXT_MPTCP);
1197 goto validate_csum;
1198 }
1199
1200 /* If this skb data are fully covered by the current mapping,
1201 * the new map would need caching, which is not supported
1202 */
1203 if (skb_is_fully_mapped(ssk, skb)) {
1204 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1205 return MAPPING_INVALID;
1206 }
1207
1208 /* will validate the next map after consuming the current one */
1209 goto validate_csum;
1210 }
1211
1212 subflow->map_seq = map_seq;
1213 subflow->map_subflow_seq = mpext->subflow_seq;
1214 subflow->map_data_len = data_len;
1215 subflow->map_valid = 1;
1216 subflow->map_data_fin = mpext->data_fin;
1217 subflow->mpc_map = mpext->mpc_map;
1218 subflow->map_csum_reqd = mpext->csum_reqd;
1219 subflow->map_csum_len = 0;
1220 subflow->map_data_csum = csum_unfold(mpext->csum);
1221
1222 /* Cfr RFC 8684 Section 3.3.0 */
1223 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1224 return MAPPING_INVALID;
1225
1226 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n",
1227 subflow->map_seq, subflow->map_subflow_seq,
1228 subflow->map_data_len, subflow->map_csum_reqd,
1229 subflow->map_data_csum);
1230
1231validate_seq:
1232 /* we revalidate valid mapping on new skb, because we must ensure
1233 * the current skb is completely covered by the available mapping
1234 */
1235 if (!validate_mapping(ssk, skb)) {
1236 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1237 return MAPPING_INVALID;
1238 }
1239
1240 skb_ext_del(skb, SKB_EXT_MPTCP);
1241
1242validate_csum:
1243 return validate_data_csum(ssk, skb, csum_reqd);
1244}
1245
1246static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1247 u64 limit)
1248{
1249 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1250 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1251 struct tcp_sock *tp = tcp_sk(ssk);
1252 u32 offset, incr, avail_len;
1253
1254 offset = tp->copied_seq - TCP_SKB_CB(skb)->seq;
1255 if (WARN_ON_ONCE(offset > skb->len))
1256 goto out;
1257
1258 avail_len = skb->len - offset;
1259 incr = limit >= avail_len ? avail_len + fin : limit;
1260
1261 pr_debug("discarding=%d len=%d offset=%d seq=%d\n", incr, skb->len,
1262 offset, subflow->map_subflow_seq);
1263 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1264 tcp_sk(ssk)->copied_seq += incr;
1265
1266out:
1267 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1268 sk_eat_skb(ssk, skb);
1269 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1270 subflow->map_valid = 0;
1271}
1272
1273/* sched mptcp worker to remove the subflow if no more data is pending */
1274static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1275{
1276 struct sock *sk = (struct sock *)msk;
1277
1278 if (likely(ssk->sk_state != TCP_CLOSE &&
1279 (ssk->sk_state != TCP_CLOSE_WAIT ||
1280 inet_sk_state_load(sk) != TCP_ESTABLISHED)))
1281 return;
1282
1283 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1284 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
1285 mptcp_schedule_work(sk);
1286}
1287
1288static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1289{
1290 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1291 unsigned long fail_tout;
1292
1293 /* graceful failure can happen only on the MPC subflow */
1294 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1295 return;
1296
1297 /* since the close timeout take precedence on the fail one,
1298 * no need to start the latter when the first is already set
1299 */
1300 if (sock_flag((struct sock *)msk, SOCK_DEAD))
1301 return;
1302
1303 /* we don't need extreme accuracy here, use a zero fail_tout as special
1304 * value meaning no fail timeout at all;
1305 */
1306 fail_tout = jiffies + TCP_RTO_MAX;
1307 if (!fail_tout)
1308 fail_tout = 1;
1309 WRITE_ONCE(subflow->fail_tout, fail_tout);
1310 tcp_send_ack(ssk);
1311
1312 mptcp_reset_tout_timer(msk, subflow->fail_tout);
1313}
1314
1315static bool subflow_check_data_avail(struct sock *ssk)
1316{
1317 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1318 enum mapping_status status;
1319 struct mptcp_sock *msk;
1320 struct sk_buff *skb;
1321
1322 if (!skb_peek(&ssk->sk_receive_queue))
1323 WRITE_ONCE(subflow->data_avail, false);
1324 if (subflow->data_avail)
1325 return true;
1326
1327 msk = mptcp_sk(subflow->conn);
1328 for (;;) {
1329 u64 ack_seq;
1330 u64 old_ack;
1331
1332 status = get_mapping_status(ssk, msk);
1333 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1334 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1335 status == MAPPING_BAD_CSUM || status == MAPPING_NODSS))
1336 goto fallback;
1337
1338 if (status != MAPPING_OK)
1339 goto no_data;
1340
1341 skb = skb_peek(&ssk->sk_receive_queue);
1342 if (WARN_ON_ONCE(!skb))
1343 goto no_data;
1344
1345 if (unlikely(!READ_ONCE(msk->can_ack)))
1346 goto fallback;
1347
1348 old_ack = READ_ONCE(msk->ack_seq);
1349 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1350 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx\n", old_ack,
1351 ack_seq);
1352 if (unlikely(before64(ack_seq, old_ack))) {
1353 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1354 continue;
1355 }
1356
1357 WRITE_ONCE(subflow->data_avail, true);
1358 break;
1359 }
1360 return true;
1361
1362no_data:
1363 subflow_sched_work_if_closed(msk, ssk);
1364 return false;
1365
1366fallback:
1367 if (!__mptcp_check_fallback(msk)) {
1368 /* RFC 8684 section 3.7. */
1369 if (status == MAPPING_BAD_CSUM &&
1370 (subflow->mp_join || subflow->valid_csum_seen)) {
1371 subflow->send_mp_fail = 1;
1372
1373 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1374 subflow->reset_transient = 0;
1375 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1376 goto reset;
1377 }
1378 mptcp_subflow_fail(msk, ssk);
1379 WRITE_ONCE(subflow->data_avail, true);
1380 return true;
1381 }
1382
1383 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1384 /* fatal protocol error, close the socket.
1385 * subflow_error_report() will introduce the appropriate barriers
1386 */
1387 subflow->reset_transient = 0;
1388 subflow->reset_reason = status == MAPPING_NODSS ?
1389 MPTCP_RST_EMIDDLEBOX :
1390 MPTCP_RST_EMPTCP;
1391
1392reset:
1393 WRITE_ONCE(ssk->sk_err, EBADMSG);
1394 tcp_set_state(ssk, TCP_CLOSE);
1395 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1396 sk_eat_skb(ssk, skb);
1397 mptcp_send_active_reset_reason(ssk);
1398 WRITE_ONCE(subflow->data_avail, false);
1399 return false;
1400 }
1401
1402 mptcp_do_fallback(ssk);
1403 }
1404
1405 skb = skb_peek(&ssk->sk_receive_queue);
1406 subflow->map_valid = 1;
1407 subflow->map_seq = READ_ONCE(msk->ack_seq);
1408 subflow->map_data_len = skb->len;
1409 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1410 WRITE_ONCE(subflow->data_avail, true);
1411 return true;
1412}
1413
1414bool mptcp_subflow_data_available(struct sock *sk)
1415{
1416 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1417
1418 /* check if current mapping is still valid */
1419 if (subflow->map_valid &&
1420 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1421 subflow->map_valid = 0;
1422 WRITE_ONCE(subflow->data_avail, false);
1423
1424 pr_debug("Done with mapping: seq=%u data_len=%u\n",
1425 subflow->map_subflow_seq,
1426 subflow->map_data_len);
1427 }
1428
1429 return subflow_check_data_avail(sk);
1430}
1431
1432/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1433 * not the ssk one.
1434 *
1435 * In mptcp, rwin is about the mptcp-level connection data.
1436 *
1437 * Data that is still on the ssk rx queue can thus be ignored,
1438 * as far as mptcp peer is concerned that data is still inflight.
1439 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1440 */
1441void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1442{
1443 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1444 const struct sock *sk = subflow->conn;
1445
1446 *space = __mptcp_space(sk);
1447 *full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1448}
1449
1450static void subflow_error_report(struct sock *ssk)
1451{
1452 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1453
1454 /* bail early if this is a no-op, so that we avoid introducing a
1455 * problematic lockdep dependency between TCP accept queue lock
1456 * and msk socket spinlock
1457 */
1458 if (!sk->sk_socket)
1459 return;
1460
1461 mptcp_data_lock(sk);
1462 if (!sock_owned_by_user(sk))
1463 __mptcp_error_report(sk);
1464 else
1465 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
1466 mptcp_data_unlock(sk);
1467}
1468
1469static void subflow_data_ready(struct sock *sk)
1470{
1471 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1472 u16 state = 1 << inet_sk_state_load(sk);
1473 struct sock *parent = subflow->conn;
1474 struct mptcp_sock *msk;
1475
1476 trace_sk_data_ready(sk);
1477
1478 msk = mptcp_sk(parent);
1479 if (state & TCPF_LISTEN) {
1480 /* MPJ subflow are removed from accept queue before reaching here,
1481 * avoid stray wakeups
1482 */
1483 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1484 return;
1485
1486 parent->sk_data_ready(parent);
1487 return;
1488 }
1489
1490 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1491 !subflow->mp_join && !(state & TCPF_CLOSE));
1492
1493 if (mptcp_subflow_data_available(sk)) {
1494 mptcp_data_ready(parent, sk);
1495
1496 /* subflow-level lowat test are not relevant.
1497 * respect the msk-level threshold eventually mandating an immediate ack
1498 */
1499 if (mptcp_data_avail(msk) < parent->sk_rcvlowat &&
1500 (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss)
1501 inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
1502 } else if (unlikely(sk->sk_err)) {
1503 subflow_error_report(sk);
1504 }
1505}
1506
1507static void subflow_write_space(struct sock *ssk)
1508{
1509 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1510
1511 mptcp_propagate_sndbuf(sk, ssk);
1512 mptcp_write_space(sk);
1513}
1514
1515static const struct inet_connection_sock_af_ops *
1516subflow_default_af_ops(struct sock *sk)
1517{
1518#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1519 if (sk->sk_family == AF_INET6)
1520 return &subflow_v6_specific;
1521#endif
1522 return &subflow_specific;
1523}
1524
1525#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1526void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1527{
1528 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1529 struct inet_connection_sock *icsk = inet_csk(sk);
1530 const struct inet_connection_sock_af_ops *target;
1531
1532 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1533
1534 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d\n",
1535 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1536
1537 if (likely(icsk->icsk_af_ops == target))
1538 return;
1539
1540 subflow->icsk_af_ops = icsk->icsk_af_ops;
1541 icsk->icsk_af_ops = target;
1542}
1543#endif
1544
1545void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1546 struct sockaddr_storage *addr,
1547 unsigned short family)
1548{
1549 memset(addr, 0, sizeof(*addr));
1550 addr->ss_family = family;
1551 if (addr->ss_family == AF_INET) {
1552 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1553
1554 if (info->family == AF_INET)
1555 in_addr->sin_addr = info->addr;
1556#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1557 else if (ipv6_addr_v4mapped(&info->addr6))
1558 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1559#endif
1560 in_addr->sin_port = info->port;
1561 }
1562#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1563 else if (addr->ss_family == AF_INET6) {
1564 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1565
1566 if (info->family == AF_INET)
1567 ipv6_addr_set_v4mapped(info->addr.s_addr,
1568 &in6_addr->sin6_addr);
1569 else
1570 in6_addr->sin6_addr = info->addr6;
1571 in6_addr->sin6_port = info->port;
1572 }
1573#endif
1574}
1575
1576int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_pm_local *local,
1577 const struct mptcp_addr_info *remote)
1578{
1579 struct mptcp_sock *msk = mptcp_sk(sk);
1580 struct mptcp_subflow_context *subflow;
1581 int local_id = local->addr.id;
1582 struct sockaddr_storage addr;
1583 int remote_id = remote->id;
1584 int err = -ENOTCONN;
1585 struct socket *sf;
1586 struct sock *ssk;
1587 u32 remote_token;
1588 int addrlen;
1589
1590 /* The userspace PM sent the request too early? */
1591 if (!mptcp_is_fully_established(sk))
1592 goto err_out;
1593
1594 err = mptcp_subflow_create_socket(sk, local->addr.family, &sf);
1595 if (err) {
1596 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCREATSKERR);
1597 pr_debug("msk=%p local=%d remote=%d create sock error: %d\n",
1598 msk, local_id, remote_id, err);
1599 goto err_out;
1600 }
1601
1602 ssk = sf->sk;
1603 subflow = mptcp_subflow_ctx(ssk);
1604 do {
1605 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1606 } while (!subflow->local_nonce);
1607
1608 /* if 'IPADDRANY', the ID will be set later, after the routing */
1609 if (local->addr.family == AF_INET) {
1610 if (!local->addr.addr.s_addr)
1611 local_id = -1;
1612#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1613 } else if (sk->sk_family == AF_INET6) {
1614 if (ipv6_addr_any(&local->addr.addr6))
1615 local_id = -1;
1616#endif
1617 }
1618
1619 if (local_id >= 0)
1620 subflow_set_local_id(subflow, local_id);
1621
1622 subflow->remote_key_valid = 1;
1623 subflow->remote_key = READ_ONCE(msk->remote_key);
1624 subflow->local_key = READ_ONCE(msk->local_key);
1625 subflow->token = msk->token;
1626 mptcp_info2sockaddr(&local->addr, &addr, ssk->sk_family);
1627
1628 addrlen = sizeof(struct sockaddr_in);
1629#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1630 if (addr.ss_family == AF_INET6)
1631 addrlen = sizeof(struct sockaddr_in6);
1632#endif
1633 ssk->sk_bound_dev_if = local->ifindex;
1634 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1635 if (err) {
1636 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXBINDERR);
1637 pr_debug("msk=%p local=%d remote=%d bind error: %d\n",
1638 msk, local_id, remote_id, err);
1639 goto failed;
1640 }
1641
1642 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1643 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d\n", msk,
1644 remote_token, local_id, remote_id);
1645 subflow->remote_token = remote_token;
1646 WRITE_ONCE(subflow->remote_id, remote_id);
1647 subflow->request_join = 1;
1648 subflow->request_bkup = !!(local->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1649 subflow->subflow_id = msk->subflow_id++;
1650 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1651
1652 sock_hold(ssk);
1653 list_add_tail(&subflow->node, &msk->conn_list);
1654 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1655 if (err && err != -EINPROGRESS) {
1656 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCONNECTERR);
1657 pr_debug("msk=%p local=%d remote=%d connect error: %d\n",
1658 msk, local_id, remote_id, err);
1659 goto failed_unlink;
1660 }
1661
1662 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTX);
1663
1664 /* discard the subflow socket */
1665 mptcp_sock_graft(ssk, sk->sk_socket);
1666 iput(SOCK_INODE(sf));
1667 WRITE_ONCE(msk->allow_infinite_fallback, false);
1668 mptcp_stop_tout_timer(sk);
1669 return 0;
1670
1671failed_unlink:
1672 list_del(&subflow->node);
1673 sock_put(mptcp_subflow_tcp_sock(subflow));
1674
1675failed:
1676 subflow->disposable = 1;
1677 sock_release(sf);
1678
1679err_out:
1680 /* we account subflows before the creation, and this failures will not
1681 * be caught by sk_state_change()
1682 */
1683 mptcp_pm_close_subflow(msk);
1684 return err;
1685}
1686
1687static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1688{
1689#ifdef CONFIG_SOCK_CGROUP_DATA
1690 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1691 *child_skcd = &child->sk_cgrp_data;
1692
1693 /* only the additional subflows created by kworkers have to be modified */
1694 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1695 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1696#ifdef CONFIG_MEMCG
1697 struct mem_cgroup *memcg = parent->sk_memcg;
1698
1699 mem_cgroup_sk_free(child);
1700 if (memcg && css_tryget(&memcg->css))
1701 child->sk_memcg = memcg;
1702#endif /* CONFIG_MEMCG */
1703
1704 cgroup_sk_free(child_skcd);
1705 *child_skcd = *parent_skcd;
1706 cgroup_sk_clone(child_skcd);
1707 }
1708#endif /* CONFIG_SOCK_CGROUP_DATA */
1709}
1710
1711static void mptcp_subflow_ops_override(struct sock *ssk)
1712{
1713#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1714 if (ssk->sk_prot == &tcpv6_prot)
1715 ssk->sk_prot = &tcpv6_prot_override;
1716 else
1717#endif
1718 ssk->sk_prot = &tcp_prot_override;
1719}
1720
1721static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1722{
1723#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1724 if (ssk->sk_prot == &tcpv6_prot_override)
1725 ssk->sk_prot = &tcpv6_prot;
1726 else
1727#endif
1728 ssk->sk_prot = &tcp_prot;
1729}
1730
1731int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1732 struct socket **new_sock)
1733{
1734 struct mptcp_subflow_context *subflow;
1735 struct net *net = sock_net(sk);
1736 struct socket *sf;
1737 int err;
1738
1739 /* un-accepted server sockets can reach here - on bad configuration
1740 * bail early to avoid greater trouble later
1741 */
1742 if (unlikely(!sk->sk_socket))
1743 return -EINVAL;
1744
1745 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
1746 if (err)
1747 return err;
1748
1749 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
1750
1751 err = security_mptcp_add_subflow(sk, sf->sk);
1752 if (err)
1753 goto err_free;
1754
1755 /* the newly created socket has to be in the same cgroup as its parent */
1756 mptcp_attach_cgroup(sk, sf->sk);
1757
1758 /* kernel sockets do not by default acquire net ref, but TCP timer
1759 * needs it.
1760 * Update ns_tracker to current stack trace and refcounted tracker.
1761 */
1762 sk_net_refcnt_upgrade(sf->sk);
1763 err = tcp_set_ulp(sf->sk, "mptcp");
1764 if (err)
1765 goto err_free;
1766
1767 mptcp_sockopt_sync_locked(mptcp_sk(sk), sf->sk);
1768 release_sock(sf->sk);
1769
1770 /* the newly created socket really belongs to the owning MPTCP
1771 * socket, even if for additional subflows the allocation is performed
1772 * by a kernel workqueue. Adjust inode references, so that the
1773 * procfs/diag interfaces really show this one belonging to the correct
1774 * user.
1775 */
1776 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1777 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1778 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1779
1780 subflow = mptcp_subflow_ctx(sf->sk);
1781 pr_debug("subflow=%p\n", subflow);
1782
1783 *new_sock = sf;
1784 sock_hold(sk);
1785 subflow->conn = sk;
1786 mptcp_subflow_ops_override(sf->sk);
1787
1788 return 0;
1789
1790err_free:
1791 release_sock(sf->sk);
1792 sock_release(sf);
1793 return err;
1794}
1795
1796static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1797 gfp_t priority)
1798{
1799 struct inet_connection_sock *icsk = inet_csk(sk);
1800 struct mptcp_subflow_context *ctx;
1801
1802 ctx = kzalloc(sizeof(*ctx), priority);
1803 if (!ctx)
1804 return NULL;
1805
1806 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1807 INIT_LIST_HEAD(&ctx->node);
1808 INIT_LIST_HEAD(&ctx->delegated_node);
1809
1810 pr_debug("subflow=%p\n", ctx);
1811
1812 ctx->tcp_sock = sk;
1813 WRITE_ONCE(ctx->local_id, -1);
1814
1815 return ctx;
1816}
1817
1818static void __subflow_state_change(struct sock *sk)
1819{
1820 struct socket_wq *wq;
1821
1822 rcu_read_lock();
1823 wq = rcu_dereference(sk->sk_wq);
1824 if (skwq_has_sleeper(wq))
1825 wake_up_interruptible_all(&wq->wait);
1826 rcu_read_unlock();
1827}
1828
1829static bool subflow_is_done(const struct sock *sk)
1830{
1831 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1832}
1833
1834static void subflow_state_change(struct sock *sk)
1835{
1836 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1837 struct sock *parent = subflow->conn;
1838 struct mptcp_sock *msk;
1839
1840 __subflow_state_change(sk);
1841
1842 msk = mptcp_sk(parent);
1843 if (subflow_simultaneous_connect(sk)) {
1844 mptcp_do_fallback(sk);
1845 pr_fallback(msk);
1846 subflow->conn_finished = 1;
1847 mptcp_propagate_state(parent, sk, subflow, NULL);
1848 }
1849
1850 /* as recvmsg() does not acquire the subflow socket for ssk selection
1851 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1852 * the data available machinery here.
1853 */
1854 if (mptcp_subflow_data_available(sk))
1855 mptcp_data_ready(parent, sk);
1856 else if (unlikely(sk->sk_err))
1857 subflow_error_report(sk);
1858
1859 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1860
1861 /* when the fallback subflow closes the rx side, trigger a 'dummy'
1862 * ingress data fin, so that the msk state will follow along
1863 */
1864 if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
1865 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
1866 mptcp_schedule_work(parent);
1867}
1868
1869void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1870{
1871 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
1872 struct request_sock *req, *head, *tail;
1873 struct mptcp_subflow_context *subflow;
1874 struct sock *sk, *ssk;
1875
1876 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
1877 * Splice the req list, so that accept() can not reach the pending ssk after
1878 * the listener socket is released below.
1879 */
1880 spin_lock_bh(&queue->rskq_lock);
1881 head = queue->rskq_accept_head;
1882 tail = queue->rskq_accept_tail;
1883 queue->rskq_accept_head = NULL;
1884 queue->rskq_accept_tail = NULL;
1885 spin_unlock_bh(&queue->rskq_lock);
1886
1887 if (!head)
1888 return;
1889
1890 /* can't acquire the msk socket lock under the subflow one,
1891 * or will cause ABBA deadlock
1892 */
1893 release_sock(listener_ssk);
1894
1895 for (req = head; req; req = req->dl_next) {
1896 ssk = req->sk;
1897 if (!sk_is_mptcp(ssk))
1898 continue;
1899
1900 subflow = mptcp_subflow_ctx(ssk);
1901 if (!subflow || !subflow->conn)
1902 continue;
1903
1904 sk = subflow->conn;
1905 sock_hold(sk);
1906
1907 lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1908 __mptcp_unaccepted_force_close(sk);
1909 release_sock(sk);
1910
1911 /* lockdep will report a false positive ABBA deadlock
1912 * between cancel_work_sync and the listener socket.
1913 * The involved locks belong to different sockets WRT
1914 * the existing AB chain.
1915 * Using a per socket key is problematic as key
1916 * deregistration requires process context and must be
1917 * performed at socket disposal time, in atomic
1918 * context.
1919 * Just tell lockdep to consider the listener socket
1920 * released here.
1921 */
1922 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1923 mptcp_cancel_work(sk);
1924 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
1925
1926 sock_put(sk);
1927 }
1928
1929 /* we are still under the listener msk socket lock */
1930 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
1931
1932 /* restore the listener queue, to let the TCP code clean it up */
1933 spin_lock_bh(&queue->rskq_lock);
1934 WARN_ON_ONCE(queue->rskq_accept_head);
1935 queue->rskq_accept_head = head;
1936 queue->rskq_accept_tail = tail;
1937 spin_unlock_bh(&queue->rskq_lock);
1938}
1939
1940static int subflow_ulp_init(struct sock *sk)
1941{
1942 struct inet_connection_sock *icsk = inet_csk(sk);
1943 struct mptcp_subflow_context *ctx;
1944 struct tcp_sock *tp = tcp_sk(sk);
1945 int err = 0;
1946
1947 /* disallow attaching ULP to a socket unless it has been
1948 * created with sock_create_kern()
1949 */
1950 if (!sk->sk_kern_sock) {
1951 err = -EOPNOTSUPP;
1952 goto out;
1953 }
1954
1955 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1956 if (!ctx) {
1957 err = -ENOMEM;
1958 goto out;
1959 }
1960
1961 pr_debug("subflow=%p, family=%d\n", ctx, sk->sk_family);
1962
1963 tp->is_mptcp = 1;
1964 ctx->icsk_af_ops = icsk->icsk_af_ops;
1965 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1966 ctx->tcp_state_change = sk->sk_state_change;
1967 ctx->tcp_error_report = sk->sk_error_report;
1968
1969 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1970 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1971
1972 sk->sk_data_ready = subflow_data_ready;
1973 sk->sk_write_space = subflow_write_space;
1974 sk->sk_state_change = subflow_state_change;
1975 sk->sk_error_report = subflow_error_report;
1976out:
1977 return err;
1978}
1979
1980static void subflow_ulp_release(struct sock *ssk)
1981{
1982 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1983 bool release = true;
1984 struct sock *sk;
1985
1986 if (!ctx)
1987 return;
1988
1989 sk = ctx->conn;
1990 if (sk) {
1991 /* if the msk has been orphaned, keep the ctx
1992 * alive, will be freed by __mptcp_close_ssk(),
1993 * when the subflow is still unaccepted
1994 */
1995 release = ctx->disposable || list_empty(&ctx->node);
1996
1997 /* inet_child_forget() does not call sk_state_change(),
1998 * explicitly trigger the socket close machinery
1999 */
2000 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
2001 &mptcp_sk(sk)->flags))
2002 mptcp_schedule_work(sk);
2003 sock_put(sk);
2004 }
2005
2006 mptcp_subflow_ops_undo_override(ssk);
2007 if (release)
2008 kfree_rcu(ctx, rcu);
2009}
2010
2011static void subflow_ulp_clone(const struct request_sock *req,
2012 struct sock *newsk,
2013 const gfp_t priority)
2014{
2015 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
2016 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
2017 struct mptcp_subflow_context *new_ctx;
2018
2019 if (!tcp_rsk(req)->is_mptcp ||
2020 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
2021 subflow_ulp_fallback(newsk, old_ctx);
2022 return;
2023 }
2024
2025 new_ctx = subflow_create_ctx(newsk, priority);
2026 if (!new_ctx) {
2027 subflow_ulp_fallback(newsk, old_ctx);
2028 return;
2029 }
2030
2031 new_ctx->conn_finished = 1;
2032 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
2033 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
2034 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
2035 new_ctx->rel_write_seq = 1;
2036
2037 if (subflow_req->mp_capable) {
2038 /* see comments in subflow_syn_recv_sock(), MPTCP connection
2039 * is fully established only after we receive the remote key
2040 */
2041 new_ctx->mp_capable = 1;
2042 new_ctx->local_key = subflow_req->local_key;
2043 new_ctx->token = subflow_req->token;
2044 new_ctx->ssn_offset = subflow_req->ssn_offset;
2045 new_ctx->idsn = subflow_req->idsn;
2046
2047 /* this is the first subflow, id is always 0 */
2048 subflow_set_local_id(new_ctx, 0);
2049 } else if (subflow_req->mp_join) {
2050 new_ctx->ssn_offset = subflow_req->ssn_offset;
2051 new_ctx->mp_join = 1;
2052 WRITE_ONCE(new_ctx->fully_established, true);
2053 new_ctx->remote_key_valid = 1;
2054 new_ctx->backup = subflow_req->backup;
2055 new_ctx->request_bkup = subflow_req->request_bkup;
2056 WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id);
2057 new_ctx->token = subflow_req->token;
2058 new_ctx->thmac = subflow_req->thmac;
2059
2060 /* the subflow req id is valid, fetched via subflow_check_req()
2061 * and subflow_token_join_request()
2062 */
2063 subflow_set_local_id(new_ctx, subflow_req->local_id);
2064 }
2065}
2066
2067static void tcp_release_cb_override(struct sock *ssk)
2068{
2069 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
2070 long status;
2071
2072 /* process and clear all the pending actions, but leave the subflow into
2073 * the napi queue. To respect locking, only the same CPU that originated
2074 * the action can touch the list. mptcp_napi_poll will take care of it.
2075 */
2076 status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0);
2077 if (status)
2078 mptcp_subflow_process_delegated(ssk, status);
2079
2080 tcp_release_cb(ssk);
2081}
2082
2083static int tcp_abort_override(struct sock *ssk, int err)
2084{
2085 /* closing a listener subflow requires a great deal of care.
2086 * keep it simple and just prevent such operation
2087 */
2088 if (inet_sk_state_load(ssk) == TCP_LISTEN)
2089 return -EINVAL;
2090
2091 return tcp_abort(ssk, err);
2092}
2093
2094static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
2095 .name = "mptcp",
2096 .owner = THIS_MODULE,
2097 .init = subflow_ulp_init,
2098 .release = subflow_ulp_release,
2099 .clone = subflow_ulp_clone,
2100};
2101
2102static int subflow_ops_init(struct request_sock_ops *subflow_ops)
2103{
2104 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
2105
2106 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
2107 subflow_ops->obj_size, 0,
2108 SLAB_ACCOUNT |
2109 SLAB_TYPESAFE_BY_RCU,
2110 NULL);
2111 if (!subflow_ops->slab)
2112 return -ENOMEM;
2113
2114 return 0;
2115}
2116
2117void __init mptcp_subflow_init(void)
2118{
2119 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
2120 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
2121 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
2122
2123 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
2124 panic("MPTCP: failed to init subflow v4 request sock ops\n");
2125
2126 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
2127 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
2128 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
2129
2130 subflow_specific = ipv4_specific;
2131 subflow_specific.conn_request = subflow_v4_conn_request;
2132 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
2133 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
2134 subflow_specific.rebuild_header = subflow_rebuild_header;
2135
2136 tcp_prot_override = tcp_prot;
2137 tcp_prot_override.release_cb = tcp_release_cb_override;
2138 tcp_prot_override.diag_destroy = tcp_abort_override;
2139
2140#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2141 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock
2142 * structures for v4 and v6 have the same size. It should not changed in
2143 * the future but better to make sure to be warned if it is no longer
2144 * the case.
2145 */
2146 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
2147
2148 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
2149 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
2150 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
2151
2152 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
2153 panic("MPTCP: failed to init subflow v6 request sock ops\n");
2154
2155 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
2156 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
2157 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
2158
2159 subflow_v6_specific = ipv6_specific;
2160 subflow_v6_specific.conn_request = subflow_v6_conn_request;
2161 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
2162 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
2163 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
2164
2165 subflow_v6m_specific = subflow_v6_specific;
2166 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
2167 subflow_v6m_specific.send_check = ipv4_specific.send_check;
2168 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
2169 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
2170 subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
2171
2172 tcpv6_prot_override = tcpv6_prot;
2173 tcpv6_prot_override.release_cb = tcp_release_cb_override;
2174 tcpv6_prot_override.diag_destroy = tcp_abort_override;
2175#endif
2176
2177 mptcp_diag_subflow_init(&subflow_ulp_ops);
2178
2179 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
2180 panic("MPTCP: failed to register subflows to ULP\n");
2181}