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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
[mirror_ubuntu-jammy-kernel.git] / net / mptcp / subflow.c
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/algapi.h>
13 #include <crypto/sha2.h>
14 #include <net/sock.h>
15 #include <net/inet_common.h>
16 #include <net/inet_hashtables.h>
17 #include <net/protocol.h>
18 #include <net/tcp.h>
19 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
20 #include <net/ip6_route.h>
21 #include <net/transp_v6.h>
22 #endif
23 #include <net/mptcp.h>
24 #include <uapi/linux/mptcp.h>
25 #include "protocol.h"
26 #include "mib.h"
27
28 #include <trace/events/mptcp.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", subflow_req);
43
44 if (subflow_req->msk)
45 sock_put((struct sock *)subflow_req->msk);
46
47 mptcp_token_destroy_request(req);
48 tcp_request_sock_ops.destructor(req);
49 }
50
51 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
52 void *hmac)
53 {
54 u8 msg[8];
55
56 put_unaligned_be32(nonce1, &msg[0]);
57 put_unaligned_be32(nonce2, &msg[4]);
58
59 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
60 }
61
62 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
63 {
64 return mptcp_is_fully_established((void *)msk) &&
65 READ_ONCE(msk->pm.accept_subflow);
66 }
67
68 /* validate received token and create truncated hmac and nonce for SYN-ACK */
69 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
70 {
71 struct mptcp_sock *msk = subflow_req->msk;
72 u8 hmac[SHA256_DIGEST_SIZE];
73
74 get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
75
76 subflow_generate_hmac(msk->local_key, msk->remote_key,
77 subflow_req->local_nonce,
78 subflow_req->remote_nonce, hmac);
79
80 subflow_req->thmac = get_unaligned_be64(hmac);
81 }
82
83 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
84 {
85 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
86 struct mptcp_sock *msk;
87 int local_id;
88
89 msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
90 if (!msk) {
91 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
92 return NULL;
93 }
94
95 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
96 if (local_id < 0) {
97 sock_put((struct sock *)msk);
98 return NULL;
99 }
100 subflow_req->local_id = local_id;
101
102 return msk;
103 }
104
105 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
106 {
107 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
108
109 subflow_req->mp_capable = 0;
110 subflow_req->mp_join = 0;
111 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
112 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
113 subflow_req->msk = NULL;
114 mptcp_token_init_request(req);
115 }
116
117 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
118 {
119 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
120 }
121
122 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
123 {
124 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
125
126 if (mpext) {
127 memset(mpext, 0, sizeof(*mpext));
128 mpext->reset_reason = reason;
129 }
130 }
131
132 /* Init mptcp request socket.
133 *
134 * Returns an error code if a JOIN has failed and a TCP reset
135 * should be sent.
136 */
137 static int subflow_check_req(struct request_sock *req,
138 const struct sock *sk_listener,
139 struct sk_buff *skb)
140 {
141 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
142 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
143 struct mptcp_options_received mp_opt;
144 bool opt_mp_capable, opt_mp_join;
145
146 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
147
148 #ifdef CONFIG_TCP_MD5SIG
149 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
150 * TCP option space.
151 */
152 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
153 return -EINVAL;
154 #endif
155
156 mptcp_get_options(sk_listener, skb, &mp_opt);
157
158 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
159 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
160 if (opt_mp_capable) {
161 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
162
163 if (opt_mp_join)
164 return 0;
165 } else if (opt_mp_join) {
166 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
167 }
168
169 if (opt_mp_capable && listener->request_mptcp) {
170 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
171
172 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
173 again:
174 do {
175 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
176 } while (subflow_req->local_key == 0);
177
178 if (unlikely(req->syncookie)) {
179 mptcp_crypto_key_sha(subflow_req->local_key,
180 &subflow_req->token,
181 &subflow_req->idsn);
182 if (mptcp_token_exists(subflow_req->token)) {
183 if (retries-- > 0)
184 goto again;
185 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
186 } else {
187 subflow_req->mp_capable = 1;
188 }
189 return 0;
190 }
191
192 err = mptcp_token_new_request(req);
193 if (err == 0)
194 subflow_req->mp_capable = 1;
195 else if (retries-- > 0)
196 goto again;
197 else
198 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
199
200 } else if (opt_mp_join && listener->request_mptcp) {
201 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
202 subflow_req->mp_join = 1;
203 subflow_req->backup = mp_opt.backup;
204 subflow_req->remote_id = mp_opt.join_id;
205 subflow_req->token = mp_opt.token;
206 subflow_req->remote_nonce = mp_opt.nonce;
207 subflow_req->msk = subflow_token_join_request(req);
208
209 /* Can't fall back to TCP in this case. */
210 if (!subflow_req->msk) {
211 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
212 return -EPERM;
213 }
214
215 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
216 pr_debug("syn inet_sport=%d %d",
217 ntohs(inet_sk(sk_listener)->inet_sport),
218 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
219 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
220 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
221 return -EPERM;
222 }
223 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
224 }
225
226 subflow_req_create_thmac(subflow_req);
227
228 if (unlikely(req->syncookie)) {
229 if (mptcp_can_accept_new_subflow(subflow_req->msk))
230 subflow_init_req_cookie_join_save(subflow_req, skb);
231 else
232 return -EPERM;
233 }
234
235 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
236 subflow_req->remote_nonce, subflow_req->msk);
237 }
238
239 return 0;
240 }
241
242 int mptcp_subflow_init_cookie_req(struct request_sock *req,
243 const struct sock *sk_listener,
244 struct sk_buff *skb)
245 {
246 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
247 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
248 struct mptcp_options_received mp_opt;
249 bool opt_mp_capable, opt_mp_join;
250 int err;
251
252 subflow_init_req(req, sk_listener);
253 mptcp_get_options(sk_listener, skb, &mp_opt);
254
255 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
256 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
257 if (opt_mp_capable && opt_mp_join)
258 return -EINVAL;
259
260 if (opt_mp_capable && listener->request_mptcp) {
261 if (mp_opt.sndr_key == 0)
262 return -EINVAL;
263
264 subflow_req->local_key = mp_opt.rcvr_key;
265 err = mptcp_token_new_request(req);
266 if (err)
267 return err;
268
269 subflow_req->mp_capable = 1;
270 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
271 } else if (opt_mp_join && listener->request_mptcp) {
272 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
273 return -EINVAL;
274
275 subflow_req->mp_join = 1;
276 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
277 }
278
279 return 0;
280 }
281 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
282
283 static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
284 struct sk_buff *skb,
285 struct flowi *fl,
286 struct request_sock *req)
287 {
288 struct dst_entry *dst;
289 int err;
290
291 tcp_rsk(req)->is_mptcp = 1;
292 subflow_init_req(req, sk);
293
294 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
295 if (!dst)
296 return NULL;
297
298 err = subflow_check_req(req, sk, skb);
299 if (err == 0)
300 return dst;
301
302 dst_release(dst);
303 if (!req->syncookie)
304 tcp_request_sock_ops.send_reset(sk, skb);
305 return NULL;
306 }
307
308 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
309 static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
310 struct sk_buff *skb,
311 struct flowi *fl,
312 struct request_sock *req)
313 {
314 struct dst_entry *dst;
315 int err;
316
317 tcp_rsk(req)->is_mptcp = 1;
318 subflow_init_req(req, sk);
319
320 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
321 if (!dst)
322 return NULL;
323
324 err = subflow_check_req(req, sk, skb);
325 if (err == 0)
326 return dst;
327
328 dst_release(dst);
329 if (!req->syncookie)
330 tcp6_request_sock_ops.send_reset(sk, skb);
331 return NULL;
332 }
333 #endif
334
335 /* validate received truncated hmac and create hmac for third ACK */
336 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
337 {
338 u8 hmac[SHA256_DIGEST_SIZE];
339 u64 thmac;
340
341 subflow_generate_hmac(subflow->remote_key, subflow->local_key,
342 subflow->remote_nonce, subflow->local_nonce,
343 hmac);
344
345 thmac = get_unaligned_be64(hmac);
346 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
347 subflow, subflow->token,
348 (unsigned long long)thmac,
349 (unsigned long long)subflow->thmac);
350
351 return thmac == subflow->thmac;
352 }
353
354 void mptcp_subflow_reset(struct sock *ssk)
355 {
356 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
357 struct sock *sk = subflow->conn;
358
359 /* must hold: tcp_done() could drop last reference on parent */
360 sock_hold(sk);
361
362 tcp_set_state(ssk, TCP_CLOSE);
363 tcp_send_active_reset(ssk, GFP_ATOMIC);
364 tcp_done(ssk);
365 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
366 schedule_work(&mptcp_sk(sk)->work))
367 return; /* worker will put sk for us */
368
369 sock_put(sk);
370 }
371
372 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
373 {
374 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
375 }
376
377 void __mptcp_set_connected(struct sock *sk)
378 {
379 if (sk->sk_state == TCP_SYN_SENT) {
380 inet_sk_state_store(sk, TCP_ESTABLISHED);
381 sk->sk_state_change(sk);
382 }
383 }
384
385 static void mptcp_set_connected(struct sock *sk)
386 {
387 mptcp_data_lock(sk);
388 if (!sock_owned_by_user(sk))
389 __mptcp_set_connected(sk);
390 else
391 set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags);
392 mptcp_data_unlock(sk);
393 }
394
395 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
396 {
397 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
398 struct mptcp_options_received mp_opt;
399 struct sock *parent = subflow->conn;
400
401 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
402
403 /* be sure no special action on any packet other than syn-ack */
404 if (subflow->conn_finished)
405 return;
406
407 mptcp_propagate_sndbuf(parent, sk);
408 subflow->rel_write_seq = 1;
409 subflow->conn_finished = 1;
410 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
411 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
412
413 mptcp_get_options(sk, skb, &mp_opt);
414 if (subflow->request_mptcp) {
415 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
416 MPTCP_INC_STATS(sock_net(sk),
417 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
418 mptcp_do_fallback(sk);
419 pr_fallback(mptcp_sk(subflow->conn));
420 goto fallback;
421 }
422
423 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
424 WRITE_ONCE(mptcp_sk(parent)->csum_enabled, true);
425 if (mp_opt.deny_join_id0)
426 WRITE_ONCE(mptcp_sk(parent)->pm.remote_deny_join_id0, true);
427 subflow->mp_capable = 1;
428 subflow->can_ack = 1;
429 subflow->remote_key = mp_opt.sndr_key;
430 pr_debug("subflow=%p, remote_key=%llu", subflow,
431 subflow->remote_key);
432 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
433 mptcp_finish_connect(sk);
434 mptcp_set_connected(parent);
435 } else if (subflow->request_join) {
436 u8 hmac[SHA256_DIGEST_SIZE];
437
438 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) {
439 subflow->reset_reason = MPTCP_RST_EMPTCP;
440 goto do_reset;
441 }
442
443 subflow->backup = mp_opt.backup;
444 subflow->thmac = mp_opt.thmac;
445 subflow->remote_nonce = mp_opt.nonce;
446 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
447 subflow, subflow->thmac, subflow->remote_nonce,
448 subflow->backup);
449
450 if (!subflow_thmac_valid(subflow)) {
451 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
452 subflow->reset_reason = MPTCP_RST_EMPTCP;
453 goto do_reset;
454 }
455
456 if (!mptcp_finish_join(sk))
457 goto do_reset;
458
459 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
460 subflow->local_nonce,
461 subflow->remote_nonce,
462 hmac);
463 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
464
465 subflow->mp_join = 1;
466 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
467
468 if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
469 pr_debug("synack inet_dport=%d %d",
470 ntohs(inet_sk(sk)->inet_dport),
471 ntohs(inet_sk(parent)->inet_dport));
472 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
473 }
474 } else if (mptcp_check_fallback(sk)) {
475 fallback:
476 mptcp_rcv_space_init(mptcp_sk(parent), sk);
477 mptcp_set_connected(parent);
478 }
479 return;
480
481 do_reset:
482 subflow->reset_transient = 0;
483 mptcp_subflow_reset(sk);
484 }
485
486 struct request_sock_ops mptcp_subflow_request_sock_ops;
487 EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops);
488 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
489
490 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
491 {
492 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
493
494 pr_debug("subflow=%p", subflow);
495
496 /* Never answer to SYNs sent to broadcast or multicast */
497 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
498 goto drop;
499
500 return tcp_conn_request(&mptcp_subflow_request_sock_ops,
501 &subflow_request_sock_ipv4_ops,
502 sk, skb);
503 drop:
504 tcp_listendrop(sk);
505 return 0;
506 }
507
508 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
509 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
510 static struct inet_connection_sock_af_ops subflow_v6_specific;
511 static struct inet_connection_sock_af_ops subflow_v6m_specific;
512 static struct proto tcpv6_prot_override;
513
514 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
515 {
516 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
517
518 pr_debug("subflow=%p", subflow);
519
520 if (skb->protocol == htons(ETH_P_IP))
521 return subflow_v4_conn_request(sk, skb);
522
523 if (!ipv6_unicast_destination(skb))
524 goto drop;
525
526 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
527 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
528 return 0;
529 }
530
531 return tcp_conn_request(&mptcp_subflow_request_sock_ops,
532 &subflow_request_sock_ipv6_ops, sk, skb);
533
534 drop:
535 tcp_listendrop(sk);
536 return 0; /* don't send reset */
537 }
538 #endif
539
540 /* validate hmac received in third ACK */
541 static bool subflow_hmac_valid(const struct request_sock *req,
542 const struct mptcp_options_received *mp_opt)
543 {
544 const struct mptcp_subflow_request_sock *subflow_req;
545 u8 hmac[SHA256_DIGEST_SIZE];
546 struct mptcp_sock *msk;
547
548 subflow_req = mptcp_subflow_rsk(req);
549 msk = subflow_req->msk;
550 if (!msk)
551 return false;
552
553 subflow_generate_hmac(msk->remote_key, msk->local_key,
554 subflow_req->remote_nonce,
555 subflow_req->local_nonce, hmac);
556
557 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
558 }
559
560 static void mptcp_sock_destruct(struct sock *sk)
561 {
562 /* if new mptcp socket isn't accepted, it is free'd
563 * from the tcp listener sockets request queue, linked
564 * from req->sk. The tcp socket is released.
565 * This calls the ULP release function which will
566 * also remove the mptcp socket, via
567 * sock_put(ctx->conn).
568 *
569 * Problem is that the mptcp socket will be in
570 * ESTABLISHED state and will not have the SOCK_DEAD flag.
571 * Both result in warnings from inet_sock_destruct.
572 */
573 if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
574 sk->sk_state = TCP_CLOSE;
575 WARN_ON_ONCE(sk->sk_socket);
576 sock_orphan(sk);
577 }
578
579 mptcp_destroy_common(mptcp_sk(sk));
580 inet_sock_destruct(sk);
581 }
582
583 static void mptcp_force_close(struct sock *sk)
584 {
585 /* the msk is not yet exposed to user-space */
586 inet_sk_state_store(sk, TCP_CLOSE);
587 sk_common_release(sk);
588 }
589
590 static void subflow_ulp_fallback(struct sock *sk,
591 struct mptcp_subflow_context *old_ctx)
592 {
593 struct inet_connection_sock *icsk = inet_csk(sk);
594
595 mptcp_subflow_tcp_fallback(sk, old_ctx);
596 icsk->icsk_ulp_ops = NULL;
597 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
598 tcp_sk(sk)->is_mptcp = 0;
599
600 mptcp_subflow_ops_undo_override(sk);
601 }
602
603 static void subflow_drop_ctx(struct sock *ssk)
604 {
605 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
606
607 if (!ctx)
608 return;
609
610 subflow_ulp_fallback(ssk, ctx);
611 if (ctx->conn)
612 sock_put(ctx->conn);
613
614 kfree_rcu(ctx, rcu);
615 }
616
617 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
618 struct mptcp_options_received *mp_opt)
619 {
620 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
621
622 subflow->remote_key = mp_opt->sndr_key;
623 subflow->fully_established = 1;
624 subflow->can_ack = 1;
625 WRITE_ONCE(msk->fully_established, true);
626 }
627
628 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
629 struct sk_buff *skb,
630 struct request_sock *req,
631 struct dst_entry *dst,
632 struct request_sock *req_unhash,
633 bool *own_req)
634 {
635 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
636 struct mptcp_subflow_request_sock *subflow_req;
637 struct mptcp_options_received mp_opt;
638 bool fallback, fallback_is_fatal;
639 struct sock *new_msk = NULL;
640 struct sock *child;
641
642 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
643
644 /* After child creation we must look for MPC even when options
645 * are not parsed
646 */
647 mp_opt.suboptions = 0;
648
649 /* hopefully temporary handling for MP_JOIN+syncookie */
650 subflow_req = mptcp_subflow_rsk(req);
651 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
652 fallback = !tcp_rsk(req)->is_mptcp;
653 if (fallback)
654 goto create_child;
655
656 /* if the sk is MP_CAPABLE, we try to fetch the client key */
657 if (subflow_req->mp_capable) {
658 /* we can receive and accept an in-window, out-of-order pkt,
659 * which may not carry the MP_CAPABLE opt even on mptcp enabled
660 * paths: always try to extract the peer key, and fallback
661 * for packets missing it.
662 * Even OoO DSS packets coming legitly after dropped or
663 * reordered MPC will cause fallback, but we don't have other
664 * options.
665 */
666 mptcp_get_options(sk, skb, &mp_opt);
667 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
668 fallback = true;
669 goto create_child;
670 }
671
672 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
673 if (!new_msk)
674 fallback = true;
675 } else if (subflow_req->mp_join) {
676 mptcp_get_options(sk, skb, &mp_opt);
677 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||
678 !subflow_hmac_valid(req, &mp_opt) ||
679 !mptcp_can_accept_new_subflow(subflow_req->msk)) {
680 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
681 fallback = true;
682 }
683 }
684
685 create_child:
686 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
687 req_unhash, own_req);
688
689 if (child && *own_req) {
690 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
691
692 tcp_rsk(req)->drop_req = false;
693
694 /* we need to fallback on ctx allocation failure and on pre-reqs
695 * checking above. In the latter scenario we additionally need
696 * to reset the context to non MPTCP status.
697 */
698 if (!ctx || fallback) {
699 if (fallback_is_fatal) {
700 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
701 goto dispose_child;
702 }
703
704 subflow_drop_ctx(child);
705 goto out;
706 }
707
708 /* ssk inherits options of listener sk */
709 ctx->setsockopt_seq = listener->setsockopt_seq;
710
711 if (ctx->mp_capable) {
712 /* this can't race with mptcp_close(), as the msk is
713 * not yet exposted to user-space
714 */
715 inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
716
717 /* record the newly created socket as the first msk
718 * subflow, but don't link it yet into conn_list
719 */
720 WRITE_ONCE(mptcp_sk(new_msk)->first, child);
721
722 /* new mpc subflow takes ownership of the newly
723 * created mptcp socket
724 */
725 new_msk->sk_destruct = mptcp_sock_destruct;
726 mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
727 mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
728 mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
729 ctx->conn = new_msk;
730 new_msk = NULL;
731
732 /* with OoO packets we can reach here without ingress
733 * mpc option
734 */
735 if (mp_opt.suboptions & OPTIONS_MPTCP_MPC)
736 mptcp_subflow_fully_established(ctx, &mp_opt);
737 } else if (ctx->mp_join) {
738 struct mptcp_sock *owner;
739
740 owner = subflow_req->msk;
741 if (!owner) {
742 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
743 goto dispose_child;
744 }
745
746 /* move the msk reference ownership to the subflow */
747 subflow_req->msk = NULL;
748 ctx->conn = (struct sock *)owner;
749
750 if (subflow_use_different_sport(owner, sk)) {
751 pr_debug("ack inet_sport=%d %d",
752 ntohs(inet_sk(sk)->inet_sport),
753 ntohs(inet_sk((struct sock *)owner)->inet_sport));
754 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
755 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
756 goto dispose_child;
757 }
758 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
759 }
760
761 if (!mptcp_finish_join(child))
762 goto dispose_child;
763
764 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
765 tcp_rsk(req)->drop_req = true;
766 }
767 }
768
769 out:
770 /* dispose of the left over mptcp master, if any */
771 if (unlikely(new_msk))
772 mptcp_force_close(new_msk);
773
774 /* check for expected invariant - should never trigger, just help
775 * catching eariler subtle bugs
776 */
777 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
778 (!mptcp_subflow_ctx(child) ||
779 !mptcp_subflow_ctx(child)->conn));
780 return child;
781
782 dispose_child:
783 subflow_drop_ctx(child);
784 tcp_rsk(req)->drop_req = true;
785 inet_csk_prepare_for_destroy_sock(child);
786 tcp_done(child);
787 req->rsk_ops->send_reset(sk, skb);
788
789 /* The last child reference will be released by the caller */
790 return child;
791 }
792
793 static struct inet_connection_sock_af_ops subflow_specific;
794 static struct proto tcp_prot_override;
795
796 enum mapping_status {
797 MAPPING_OK,
798 MAPPING_INVALID,
799 MAPPING_EMPTY,
800 MAPPING_DATA_FIN,
801 MAPPING_DUMMY
802 };
803
804 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
805 {
806 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
807 ssn, subflow->map_subflow_seq, subflow->map_data_len);
808 }
809
810 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
811 {
812 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
813 unsigned int skb_consumed;
814
815 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
816 if (WARN_ON_ONCE(skb_consumed >= skb->len))
817 return true;
818
819 return skb->len - skb_consumed <= subflow->map_data_len -
820 mptcp_subflow_get_map_offset(subflow);
821 }
822
823 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
824 {
825 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
826 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
827
828 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
829 /* Mapping covers data later in the subflow stream,
830 * currently unsupported.
831 */
832 dbg_bad_map(subflow, ssn);
833 return false;
834 }
835 if (unlikely(!before(ssn, subflow->map_subflow_seq +
836 subflow->map_data_len))) {
837 /* Mapping does covers past subflow data, invalid */
838 dbg_bad_map(subflow, ssn);
839 return false;
840 }
841 return true;
842 }
843
844 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
845 bool csum_reqd)
846 {
847 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
848 struct csum_pseudo_header header;
849 u32 offset, seq, delta;
850 __wsum csum;
851 int len;
852
853 if (!csum_reqd)
854 return MAPPING_OK;
855
856 /* mapping already validated on previous traversal */
857 if (subflow->map_csum_len == subflow->map_data_len)
858 return MAPPING_OK;
859
860 /* traverse the receive queue, ensuring it contains a full
861 * DSS mapping and accumulating the related csum.
862 * Preserve the accoumlate csum across multiple calls, to compute
863 * the csum only once
864 */
865 delta = subflow->map_data_len - subflow->map_csum_len;
866 for (;;) {
867 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
868 offset = seq - TCP_SKB_CB(skb)->seq;
869
870 /* if the current skb has not been accounted yet, csum its contents
871 * up to the amount covered by the current DSS
872 */
873 if (offset < skb->len) {
874 __wsum csum;
875
876 len = min(skb->len - offset, delta);
877 csum = skb_checksum(skb, offset, len, 0);
878 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
879 subflow->map_csum_len);
880
881 delta -= len;
882 subflow->map_csum_len += len;
883 }
884 if (delta == 0)
885 break;
886
887 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
888 /* if this subflow is closed, the partial mapping
889 * will be never completed; flush the pending skbs, so
890 * that subflow_sched_work_if_closed() can kick in
891 */
892 if (unlikely(ssk->sk_state == TCP_CLOSE))
893 while ((skb = skb_peek(&ssk->sk_receive_queue)))
894 sk_eat_skb(ssk, skb);
895
896 /* not enough data to validate the csum */
897 return MAPPING_EMPTY;
898 }
899
900 /* the DSS mapping for next skbs will be validated later,
901 * when a get_mapping_status call will process such skb
902 */
903 skb = skb->next;
904 }
905
906 /* note that 'map_data_len' accounts only for the carried data, does
907 * not include the eventual seq increment due to the data fin,
908 * while the pseudo header requires the original DSS data len,
909 * including that
910 */
911 header.data_seq = cpu_to_be64(subflow->map_seq);
912 header.subflow_seq = htonl(subflow->map_subflow_seq);
913 header.data_len = htons(subflow->map_data_len + subflow->map_data_fin);
914 header.csum = 0;
915
916 csum = csum_partial(&header, sizeof(header), subflow->map_data_csum);
917 if (unlikely(csum_fold(csum))) {
918 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
919 subflow->send_mp_fail = 1;
920 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPFAILTX);
921 return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
922 }
923
924 return MAPPING_OK;
925 }
926
927 static enum mapping_status get_mapping_status(struct sock *ssk,
928 struct mptcp_sock *msk)
929 {
930 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
931 bool csum_reqd = READ_ONCE(msk->csum_enabled);
932 struct mptcp_ext *mpext;
933 struct sk_buff *skb;
934 u16 data_len;
935 u64 map_seq;
936
937 skb = skb_peek(&ssk->sk_receive_queue);
938 if (!skb)
939 return MAPPING_EMPTY;
940
941 if (mptcp_check_fallback(ssk))
942 return MAPPING_DUMMY;
943
944 mpext = mptcp_get_ext(skb);
945 if (!mpext || !mpext->use_map) {
946 if (!subflow->map_valid && !skb->len) {
947 /* the TCP stack deliver 0 len FIN pkt to the receive
948 * queue, that is the only 0len pkts ever expected here,
949 * and we can admit no mapping only for 0 len pkts
950 */
951 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
952 WARN_ONCE(1, "0len seq %d:%d flags %x",
953 TCP_SKB_CB(skb)->seq,
954 TCP_SKB_CB(skb)->end_seq,
955 TCP_SKB_CB(skb)->tcp_flags);
956 sk_eat_skb(ssk, skb);
957 return MAPPING_EMPTY;
958 }
959
960 if (!subflow->map_valid)
961 return MAPPING_INVALID;
962
963 goto validate_seq;
964 }
965
966 trace_get_mapping_status(mpext);
967
968 data_len = mpext->data_len;
969 if (data_len == 0) {
970 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
971 return MAPPING_INVALID;
972 }
973
974 if (mpext->data_fin == 1) {
975 if (data_len == 1) {
976 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
977 mpext->dsn64);
978 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
979 if (subflow->map_valid) {
980 /* A DATA_FIN might arrive in a DSS
981 * option before the previous mapping
982 * has been fully consumed. Continue
983 * handling the existing mapping.
984 */
985 skb_ext_del(skb, SKB_EXT_MPTCP);
986 return MAPPING_OK;
987 } else {
988 if (updated && schedule_work(&msk->work))
989 sock_hold((struct sock *)msk);
990
991 return MAPPING_DATA_FIN;
992 }
993 } else {
994 u64 data_fin_seq = mpext->data_seq + data_len - 1;
995
996 /* If mpext->data_seq is a 32-bit value, data_fin_seq
997 * must also be limited to 32 bits.
998 */
999 if (!mpext->dsn64)
1000 data_fin_seq &= GENMASK_ULL(31, 0);
1001
1002 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1003 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
1004 data_fin_seq, mpext->dsn64);
1005 }
1006
1007 /* Adjust for DATA_FIN using 1 byte of sequence space */
1008 data_len--;
1009 }
1010
1011 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1012 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1013
1014 if (subflow->map_valid) {
1015 /* Allow replacing only with an identical map */
1016 if (subflow->map_seq == map_seq &&
1017 subflow->map_subflow_seq == mpext->subflow_seq &&
1018 subflow->map_data_len == data_len &&
1019 subflow->map_csum_reqd == mpext->csum_reqd) {
1020 skb_ext_del(skb, SKB_EXT_MPTCP);
1021 goto validate_csum;
1022 }
1023
1024 /* If this skb data are fully covered by the current mapping,
1025 * the new map would need caching, which is not supported
1026 */
1027 if (skb_is_fully_mapped(ssk, skb)) {
1028 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1029 return MAPPING_INVALID;
1030 }
1031
1032 /* will validate the next map after consuming the current one */
1033 goto validate_csum;
1034 }
1035
1036 subflow->map_seq = map_seq;
1037 subflow->map_subflow_seq = mpext->subflow_seq;
1038 subflow->map_data_len = data_len;
1039 subflow->map_valid = 1;
1040 subflow->map_data_fin = mpext->data_fin;
1041 subflow->mpc_map = mpext->mpc_map;
1042 subflow->map_csum_reqd = mpext->csum_reqd;
1043 subflow->map_csum_len = 0;
1044 subflow->map_data_csum = csum_unfold(mpext->csum);
1045
1046 /* Cfr RFC 8684 Section 3.3.0 */
1047 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1048 return MAPPING_INVALID;
1049
1050 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1051 subflow->map_seq, subflow->map_subflow_seq,
1052 subflow->map_data_len, subflow->map_csum_reqd,
1053 subflow->map_data_csum);
1054
1055 validate_seq:
1056 /* we revalidate valid mapping on new skb, because we must ensure
1057 * the current skb is completely covered by the available mapping
1058 */
1059 if (!validate_mapping(ssk, skb)) {
1060 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1061 return MAPPING_INVALID;
1062 }
1063
1064 skb_ext_del(skb, SKB_EXT_MPTCP);
1065
1066 validate_csum:
1067 return validate_data_csum(ssk, skb, csum_reqd);
1068 }
1069
1070 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1071 u64 limit)
1072 {
1073 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1074 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1075 u32 incr;
1076
1077 incr = limit >= skb->len ? skb->len + fin : limit;
1078
1079 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1080 subflow->map_subflow_seq);
1081 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1082 tcp_sk(ssk)->copied_seq += incr;
1083 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1084 sk_eat_skb(ssk, skb);
1085 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1086 subflow->map_valid = 0;
1087 }
1088
1089 /* sched mptcp worker to remove the subflow if no more data is pending */
1090 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1091 {
1092 struct sock *sk = (struct sock *)msk;
1093
1094 if (likely(ssk->sk_state != TCP_CLOSE))
1095 return;
1096
1097 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1098 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
1099 sock_hold(sk);
1100 if (!schedule_work(&msk->work))
1101 sock_put(sk);
1102 }
1103 }
1104
1105 static bool subflow_check_data_avail(struct sock *ssk)
1106 {
1107 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1108 enum mapping_status status;
1109 struct mptcp_sock *msk;
1110 struct sk_buff *skb;
1111
1112 if (!skb_peek(&ssk->sk_receive_queue))
1113 WRITE_ONCE(subflow->data_avail, 0);
1114 if (subflow->data_avail)
1115 return true;
1116
1117 msk = mptcp_sk(subflow->conn);
1118 for (;;) {
1119 u64 ack_seq;
1120 u64 old_ack;
1121
1122 status = get_mapping_status(ssk, msk);
1123 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1124 if (unlikely(status == MAPPING_INVALID))
1125 goto fallback;
1126
1127 if (unlikely(status == MAPPING_DUMMY))
1128 goto fallback;
1129
1130 if (status != MAPPING_OK)
1131 goto no_data;
1132
1133 skb = skb_peek(&ssk->sk_receive_queue);
1134 if (WARN_ON_ONCE(!skb))
1135 goto no_data;
1136
1137 /* if msk lacks the remote key, this subflow must provide an
1138 * MP_CAPABLE-based mapping
1139 */
1140 if (unlikely(!READ_ONCE(msk->can_ack))) {
1141 if (!subflow->mpc_map)
1142 goto fallback;
1143 WRITE_ONCE(msk->remote_key, subflow->remote_key);
1144 WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1145 WRITE_ONCE(msk->can_ack, true);
1146 }
1147
1148 old_ack = READ_ONCE(msk->ack_seq);
1149 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1150 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1151 ack_seq);
1152 if (unlikely(before64(ack_seq, old_ack))) {
1153 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1154 continue;
1155 }
1156
1157 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1158 break;
1159 }
1160 return true;
1161
1162 no_data:
1163 subflow_sched_work_if_closed(msk, ssk);
1164 return false;
1165
1166 fallback:
1167 /* RFC 8684 section 3.7. */
1168 if (subflow->send_mp_fail) {
1169 if (mptcp_has_another_subflow(ssk)) {
1170 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1171 sk_eat_skb(ssk, skb);
1172 }
1173 ssk->sk_err = EBADMSG;
1174 tcp_set_state(ssk, TCP_CLOSE);
1175 subflow->reset_transient = 0;
1176 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1177 tcp_send_active_reset(ssk, GFP_ATOMIC);
1178 WRITE_ONCE(subflow->data_avail, 0);
1179 return true;
1180 }
1181
1182 if (subflow->mp_join || subflow->fully_established) {
1183 /* fatal protocol error, close the socket.
1184 * subflow_error_report() will introduce the appropriate barriers
1185 */
1186 ssk->sk_err = EBADMSG;
1187 tcp_set_state(ssk, TCP_CLOSE);
1188 subflow->reset_transient = 0;
1189 subflow->reset_reason = MPTCP_RST_EMPTCP;
1190 tcp_send_active_reset(ssk, GFP_ATOMIC);
1191 WRITE_ONCE(subflow->data_avail, 0);
1192 return false;
1193 }
1194
1195 __mptcp_do_fallback(msk);
1196 skb = skb_peek(&ssk->sk_receive_queue);
1197 subflow->map_valid = 1;
1198 subflow->map_seq = READ_ONCE(msk->ack_seq);
1199 subflow->map_data_len = skb->len;
1200 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1201 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1202 return true;
1203 }
1204
1205 bool mptcp_subflow_data_available(struct sock *sk)
1206 {
1207 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1208
1209 /* check if current mapping is still valid */
1210 if (subflow->map_valid &&
1211 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1212 subflow->map_valid = 0;
1213 WRITE_ONCE(subflow->data_avail, 0);
1214
1215 pr_debug("Done with mapping: seq=%u data_len=%u",
1216 subflow->map_subflow_seq,
1217 subflow->map_data_len);
1218 }
1219
1220 return subflow_check_data_avail(sk);
1221 }
1222
1223 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1224 * not the ssk one.
1225 *
1226 * In mptcp, rwin is about the mptcp-level connection data.
1227 *
1228 * Data that is still on the ssk rx queue can thus be ignored,
1229 * as far as mptcp peer is concerned that data is still inflight.
1230 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1231 */
1232 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1233 {
1234 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1235 const struct sock *sk = subflow->conn;
1236
1237 *space = __mptcp_space(sk);
1238 *full_space = tcp_full_space(sk);
1239 }
1240
1241 void __mptcp_error_report(struct sock *sk)
1242 {
1243 struct mptcp_subflow_context *subflow;
1244 struct mptcp_sock *msk = mptcp_sk(sk);
1245
1246 mptcp_for_each_subflow(msk, subflow) {
1247 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1248 int err = sock_error(ssk);
1249
1250 if (!err)
1251 continue;
1252
1253 /* only propagate errors on fallen-back sockets or
1254 * on MPC connect
1255 */
1256 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1257 continue;
1258
1259 inet_sk_state_store(sk, inet_sk_state_load(ssk));
1260 sk->sk_err = -err;
1261
1262 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1263 smp_wmb();
1264 sk_error_report(sk);
1265 break;
1266 }
1267 }
1268
1269 static void subflow_error_report(struct sock *ssk)
1270 {
1271 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1272
1273 mptcp_data_lock(sk);
1274 if (!sock_owned_by_user(sk))
1275 __mptcp_error_report(sk);
1276 else
1277 set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->flags);
1278 mptcp_data_unlock(sk);
1279 }
1280
1281 static void subflow_data_ready(struct sock *sk)
1282 {
1283 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1284 u16 state = 1 << inet_sk_state_load(sk);
1285 struct sock *parent = subflow->conn;
1286 struct mptcp_sock *msk;
1287
1288 msk = mptcp_sk(parent);
1289 if (state & TCPF_LISTEN) {
1290 /* MPJ subflow are removed from accept queue before reaching here,
1291 * avoid stray wakeups
1292 */
1293 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1294 return;
1295
1296 set_bit(MPTCP_DATA_READY, &msk->flags);
1297 parent->sk_data_ready(parent);
1298 return;
1299 }
1300
1301 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1302 !subflow->mp_join && !(state & TCPF_CLOSE));
1303
1304 if (mptcp_subflow_data_available(sk))
1305 mptcp_data_ready(parent, sk);
1306 else if (unlikely(sk->sk_err))
1307 subflow_error_report(sk);
1308 }
1309
1310 static void subflow_write_space(struct sock *ssk)
1311 {
1312 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1313
1314 mptcp_propagate_sndbuf(sk, ssk);
1315 mptcp_write_space(sk);
1316 }
1317
1318 static struct inet_connection_sock_af_ops *
1319 subflow_default_af_ops(struct sock *sk)
1320 {
1321 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1322 if (sk->sk_family == AF_INET6)
1323 return &subflow_v6_specific;
1324 #endif
1325 return &subflow_specific;
1326 }
1327
1328 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1329 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1330 {
1331 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1332 struct inet_connection_sock *icsk = inet_csk(sk);
1333 struct inet_connection_sock_af_ops *target;
1334
1335 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1336
1337 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1338 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1339
1340 if (likely(icsk->icsk_af_ops == target))
1341 return;
1342
1343 subflow->icsk_af_ops = icsk->icsk_af_ops;
1344 icsk->icsk_af_ops = target;
1345 }
1346 #endif
1347
1348 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1349 struct sockaddr_storage *addr,
1350 unsigned short family)
1351 {
1352 memset(addr, 0, sizeof(*addr));
1353 addr->ss_family = family;
1354 if (addr->ss_family == AF_INET) {
1355 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1356
1357 if (info->family == AF_INET)
1358 in_addr->sin_addr = info->addr;
1359 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1360 else if (ipv6_addr_v4mapped(&info->addr6))
1361 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1362 #endif
1363 in_addr->sin_port = info->port;
1364 }
1365 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1366 else if (addr->ss_family == AF_INET6) {
1367 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1368
1369 if (info->family == AF_INET)
1370 ipv6_addr_set_v4mapped(info->addr.s_addr,
1371 &in6_addr->sin6_addr);
1372 else
1373 in6_addr->sin6_addr = info->addr6;
1374 in6_addr->sin6_port = info->port;
1375 }
1376 #endif
1377 }
1378
1379 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1380 const struct mptcp_addr_info *remote)
1381 {
1382 struct mptcp_sock *msk = mptcp_sk(sk);
1383 struct mptcp_subflow_context *subflow;
1384 struct sockaddr_storage addr;
1385 int remote_id = remote->id;
1386 int local_id = loc->id;
1387 struct socket *sf;
1388 struct sock *ssk;
1389 u32 remote_token;
1390 int addrlen;
1391 int ifindex;
1392 u8 flags;
1393 int err;
1394
1395 if (!mptcp_is_fully_established(sk))
1396 return -ENOTCONN;
1397
1398 err = mptcp_subflow_create_socket(sk, &sf);
1399 if (err)
1400 return err;
1401
1402 ssk = sf->sk;
1403 subflow = mptcp_subflow_ctx(ssk);
1404 do {
1405 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1406 } while (!subflow->local_nonce);
1407
1408 if (!local_id) {
1409 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
1410 if (err < 0)
1411 goto failed;
1412
1413 local_id = err;
1414 }
1415
1416 mptcp_pm_get_flags_and_ifindex_by_id(sock_net(sk), local_id,
1417 &flags, &ifindex);
1418 subflow->remote_key = msk->remote_key;
1419 subflow->local_key = msk->local_key;
1420 subflow->token = msk->token;
1421 mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1422
1423 addrlen = sizeof(struct sockaddr_in);
1424 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1425 if (addr.ss_family == AF_INET6)
1426 addrlen = sizeof(struct sockaddr_in6);
1427 #endif
1428 ssk->sk_bound_dev_if = ifindex;
1429 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1430 if (err)
1431 goto failed;
1432
1433 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1434 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1435 remote_token, local_id, remote_id);
1436 subflow->remote_token = remote_token;
1437 subflow->local_id = local_id;
1438 subflow->remote_id = remote_id;
1439 subflow->request_join = 1;
1440 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1441 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1442
1443 mptcp_add_pending_subflow(msk, subflow);
1444 mptcp_sockopt_sync(msk, ssk);
1445 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1446 if (err && err != -EINPROGRESS)
1447 goto failed_unlink;
1448
1449 /* discard the subflow socket */
1450 mptcp_sock_graft(ssk, sk->sk_socket);
1451 iput(SOCK_INODE(sf));
1452 return err;
1453
1454 failed_unlink:
1455 spin_lock_bh(&msk->join_list_lock);
1456 list_del(&subflow->node);
1457 spin_unlock_bh(&msk->join_list_lock);
1458 sock_put(mptcp_subflow_tcp_sock(subflow));
1459
1460 failed:
1461 subflow->disposable = 1;
1462 sock_release(sf);
1463 return err;
1464 }
1465
1466 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1467 {
1468 #ifdef CONFIG_SOCK_CGROUP_DATA
1469 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1470 *child_skcd = &child->sk_cgrp_data;
1471
1472 /* only the additional subflows created by kworkers have to be modified */
1473 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1474 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1475 #ifdef CONFIG_MEMCG
1476 struct mem_cgroup *memcg = parent->sk_memcg;
1477
1478 mem_cgroup_sk_free(child);
1479 if (memcg && css_tryget(&memcg->css))
1480 child->sk_memcg = memcg;
1481 #endif /* CONFIG_MEMCG */
1482
1483 cgroup_sk_free(child_skcd);
1484 *child_skcd = *parent_skcd;
1485 cgroup_sk_clone(child_skcd);
1486 }
1487 #endif /* CONFIG_SOCK_CGROUP_DATA */
1488 }
1489
1490 static void mptcp_subflow_ops_override(struct sock *ssk)
1491 {
1492 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1493 if (ssk->sk_prot == &tcpv6_prot)
1494 ssk->sk_prot = &tcpv6_prot_override;
1495 else
1496 #endif
1497 ssk->sk_prot = &tcp_prot_override;
1498 }
1499
1500 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1501 {
1502 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1503 if (ssk->sk_prot == &tcpv6_prot_override)
1504 ssk->sk_prot = &tcpv6_prot;
1505 else
1506 #endif
1507 ssk->sk_prot = &tcp_prot;
1508 }
1509 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
1510 {
1511 struct mptcp_subflow_context *subflow;
1512 struct net *net = sock_net(sk);
1513 struct socket *sf;
1514 int err;
1515
1516 /* un-accepted server sockets can reach here - on bad configuration
1517 * bail early to avoid greater trouble later
1518 */
1519 if (unlikely(!sk->sk_socket))
1520 return -EINVAL;
1521
1522 err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
1523 &sf);
1524 if (err)
1525 return err;
1526
1527 lock_sock(sf->sk);
1528
1529 /* the newly created socket has to be in the same cgroup as its parent */
1530 mptcp_attach_cgroup(sk, sf->sk);
1531
1532 /* kernel sockets do not by default acquire net ref, but TCP timer
1533 * needs it.
1534 */
1535 sf->sk->sk_net_refcnt = 1;
1536 get_net(net);
1537 #ifdef CONFIG_PROC_FS
1538 this_cpu_add(*net->core.sock_inuse, 1);
1539 #endif
1540 err = tcp_set_ulp(sf->sk, "mptcp");
1541 release_sock(sf->sk);
1542
1543 if (err) {
1544 sock_release(sf);
1545 return err;
1546 }
1547
1548 /* the newly created socket really belongs to the owning MPTCP master
1549 * socket, even if for additional subflows the allocation is performed
1550 * by a kernel workqueue. Adjust inode references, so that the
1551 * procfs/diag interaces really show this one belonging to the correct
1552 * user.
1553 */
1554 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1555 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1556 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1557
1558 subflow = mptcp_subflow_ctx(sf->sk);
1559 pr_debug("subflow=%p", subflow);
1560
1561 *new_sock = sf;
1562 sock_hold(sk);
1563 subflow->conn = sk;
1564 mptcp_subflow_ops_override(sf->sk);
1565
1566 return 0;
1567 }
1568
1569 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1570 gfp_t priority)
1571 {
1572 struct inet_connection_sock *icsk = inet_csk(sk);
1573 struct mptcp_subflow_context *ctx;
1574
1575 ctx = kzalloc(sizeof(*ctx), priority);
1576 if (!ctx)
1577 return NULL;
1578
1579 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1580 INIT_LIST_HEAD(&ctx->node);
1581 INIT_LIST_HEAD(&ctx->delegated_node);
1582
1583 pr_debug("subflow=%p", ctx);
1584
1585 ctx->tcp_sock = sk;
1586
1587 return ctx;
1588 }
1589
1590 static void __subflow_state_change(struct sock *sk)
1591 {
1592 struct socket_wq *wq;
1593
1594 rcu_read_lock();
1595 wq = rcu_dereference(sk->sk_wq);
1596 if (skwq_has_sleeper(wq))
1597 wake_up_interruptible_all(&wq->wait);
1598 rcu_read_unlock();
1599 }
1600
1601 static bool subflow_is_done(const struct sock *sk)
1602 {
1603 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1604 }
1605
1606 static void subflow_state_change(struct sock *sk)
1607 {
1608 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1609 struct sock *parent = subflow->conn;
1610
1611 __subflow_state_change(sk);
1612
1613 if (subflow_simultaneous_connect(sk)) {
1614 mptcp_propagate_sndbuf(parent, sk);
1615 mptcp_do_fallback(sk);
1616 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1617 pr_fallback(mptcp_sk(parent));
1618 subflow->conn_finished = 1;
1619 mptcp_set_connected(parent);
1620 }
1621
1622 /* as recvmsg() does not acquire the subflow socket for ssk selection
1623 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1624 * the data available machinery here.
1625 */
1626 if (mptcp_subflow_data_available(sk))
1627 mptcp_data_ready(parent, sk);
1628 else if (unlikely(sk->sk_err))
1629 subflow_error_report(sk);
1630
1631 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1632
1633 if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1634 !subflow->rx_eof && subflow_is_done(sk)) {
1635 subflow->rx_eof = 1;
1636 mptcp_subflow_eof(parent);
1637 }
1638 }
1639
1640 static int subflow_ulp_init(struct sock *sk)
1641 {
1642 struct inet_connection_sock *icsk = inet_csk(sk);
1643 struct mptcp_subflow_context *ctx;
1644 struct tcp_sock *tp = tcp_sk(sk);
1645 int err = 0;
1646
1647 /* disallow attaching ULP to a socket unless it has been
1648 * created with sock_create_kern()
1649 */
1650 if (!sk->sk_kern_sock) {
1651 err = -EOPNOTSUPP;
1652 goto out;
1653 }
1654
1655 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1656 if (!ctx) {
1657 err = -ENOMEM;
1658 goto out;
1659 }
1660
1661 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1662
1663 tp->is_mptcp = 1;
1664 ctx->icsk_af_ops = icsk->icsk_af_ops;
1665 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1666 ctx->tcp_data_ready = sk->sk_data_ready;
1667 ctx->tcp_state_change = sk->sk_state_change;
1668 ctx->tcp_write_space = sk->sk_write_space;
1669 ctx->tcp_error_report = sk->sk_error_report;
1670 sk->sk_data_ready = subflow_data_ready;
1671 sk->sk_write_space = subflow_write_space;
1672 sk->sk_state_change = subflow_state_change;
1673 sk->sk_error_report = subflow_error_report;
1674 out:
1675 return err;
1676 }
1677
1678 static void subflow_ulp_release(struct sock *ssk)
1679 {
1680 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1681 bool release = true;
1682 struct sock *sk;
1683
1684 if (!ctx)
1685 return;
1686
1687 sk = ctx->conn;
1688 if (sk) {
1689 /* if the msk has been orphaned, keep the ctx
1690 * alive, will be freed by __mptcp_close_ssk(),
1691 * when the subflow is still unaccepted
1692 */
1693 release = ctx->disposable || list_empty(&ctx->node);
1694 sock_put(sk);
1695 }
1696
1697 mptcp_subflow_ops_undo_override(ssk);
1698 if (release)
1699 kfree_rcu(ctx, rcu);
1700 }
1701
1702 static void subflow_ulp_clone(const struct request_sock *req,
1703 struct sock *newsk,
1704 const gfp_t priority)
1705 {
1706 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1707 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1708 struct mptcp_subflow_context *new_ctx;
1709
1710 if (!tcp_rsk(req)->is_mptcp ||
1711 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1712 subflow_ulp_fallback(newsk, old_ctx);
1713 return;
1714 }
1715
1716 new_ctx = subflow_create_ctx(newsk, priority);
1717 if (!new_ctx) {
1718 subflow_ulp_fallback(newsk, old_ctx);
1719 return;
1720 }
1721
1722 new_ctx->conn_finished = 1;
1723 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1724 new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
1725 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1726 new_ctx->tcp_write_space = old_ctx->tcp_write_space;
1727 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1728 new_ctx->rel_write_seq = 1;
1729 new_ctx->tcp_sock = newsk;
1730
1731 if (subflow_req->mp_capable) {
1732 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1733 * is fully established only after we receive the remote key
1734 */
1735 new_ctx->mp_capable = 1;
1736 new_ctx->local_key = subflow_req->local_key;
1737 new_ctx->token = subflow_req->token;
1738 new_ctx->ssn_offset = subflow_req->ssn_offset;
1739 new_ctx->idsn = subflow_req->idsn;
1740 } else if (subflow_req->mp_join) {
1741 new_ctx->ssn_offset = subflow_req->ssn_offset;
1742 new_ctx->mp_join = 1;
1743 new_ctx->fully_established = 1;
1744 new_ctx->backup = subflow_req->backup;
1745 new_ctx->local_id = subflow_req->local_id;
1746 new_ctx->remote_id = subflow_req->remote_id;
1747 new_ctx->token = subflow_req->token;
1748 new_ctx->thmac = subflow_req->thmac;
1749 }
1750 }
1751
1752 static void tcp_release_cb_override(struct sock *ssk)
1753 {
1754 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1755
1756 if (mptcp_subflow_has_delegated_action(subflow))
1757 mptcp_subflow_process_delegated(ssk);
1758
1759 tcp_release_cb(ssk);
1760 }
1761
1762 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1763 .name = "mptcp",
1764 .owner = THIS_MODULE,
1765 .init = subflow_ulp_init,
1766 .release = subflow_ulp_release,
1767 .clone = subflow_ulp_clone,
1768 };
1769
1770 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1771 {
1772 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1773 subflow_ops->slab_name = "request_sock_subflow";
1774
1775 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1776 subflow_ops->obj_size, 0,
1777 SLAB_ACCOUNT |
1778 SLAB_TYPESAFE_BY_RCU,
1779 NULL);
1780 if (!subflow_ops->slab)
1781 return -ENOMEM;
1782
1783 subflow_ops->destructor = subflow_req_destructor;
1784
1785 return 0;
1786 }
1787
1788 void __init mptcp_subflow_init(void)
1789 {
1790 mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
1791 if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
1792 panic("MPTCP: failed to init subflow request sock ops\n");
1793
1794 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1795 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1796
1797 subflow_specific = ipv4_specific;
1798 subflow_specific.conn_request = subflow_v4_conn_request;
1799 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1800 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1801
1802 tcp_prot_override = tcp_prot;
1803 tcp_prot_override.release_cb = tcp_release_cb_override;
1804
1805 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1806 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1807 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1808
1809 subflow_v6_specific = ipv6_specific;
1810 subflow_v6_specific.conn_request = subflow_v6_conn_request;
1811 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1812 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1813
1814 subflow_v6m_specific = subflow_v6_specific;
1815 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1816 subflow_v6m_specific.send_check = ipv4_specific.send_check;
1817 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1818 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1819 subflow_v6m_specific.net_frag_header_len = 0;
1820
1821 tcpv6_prot_override = tcpv6_prot;
1822 tcpv6_prot_override.release_cb = tcp_release_cb_override;
1823 #endif
1824
1825 mptcp_diag_subflow_init(&subflow_ulp_ops);
1826
1827 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1828 panic("MPTCP: failed to register subflows to ULP\n");
1829 }
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