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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/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
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", 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
51static 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
62static 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 */
69static 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
83static 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
105static 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
117static 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
122static 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 */
137static 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
145 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
146
147#ifdef CONFIG_TCP_MD5SIG
148 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
149 * TCP option space.
150 */
151 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
152 return -EINVAL;
153#endif
154
155 mptcp_get_options(sk_listener, skb, &mp_opt);
156
157 if (mp_opt.mp_capable) {
158 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
159
160 if (mp_opt.mp_join)
161 return 0;
162 } else if (mp_opt.mp_join) {
163 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
164 }
165
166 if (mp_opt.mp_capable && listener->request_mptcp) {
167 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
168
169 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
170again:
171 do {
172 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
173 } while (subflow_req->local_key == 0);
174
175 if (unlikely(req->syncookie)) {
176 mptcp_crypto_key_sha(subflow_req->local_key,
177 &subflow_req->token,
178 &subflow_req->idsn);
179 if (mptcp_token_exists(subflow_req->token)) {
180 if (retries-- > 0)
181 goto again;
182 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
183 } else {
184 subflow_req->mp_capable = 1;
185 }
186 return 0;
187 }
188
189 err = mptcp_token_new_request(req);
190 if (err == 0)
191 subflow_req->mp_capable = 1;
192 else if (retries-- > 0)
193 goto again;
194 else
195 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
196
197 } else if (mp_opt.mp_join && listener->request_mptcp) {
198 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
199 subflow_req->mp_join = 1;
200 subflow_req->backup = mp_opt.backup;
201 subflow_req->remote_id = mp_opt.join_id;
202 subflow_req->token = mp_opt.token;
203 subflow_req->remote_nonce = mp_opt.nonce;
204 subflow_req->msk = subflow_token_join_request(req);
205
206 /* Can't fall back to TCP in this case. */
207 if (!subflow_req->msk) {
208 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
209 return -EPERM;
210 }
211
212 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
213 pr_debug("syn inet_sport=%d %d",
214 ntohs(inet_sk(sk_listener)->inet_sport),
215 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
216 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
217 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
218 return -EPERM;
219 }
220 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
221 }
222
223 subflow_req_create_thmac(subflow_req);
224
225 if (unlikely(req->syncookie)) {
226 if (mptcp_can_accept_new_subflow(subflow_req->msk))
227 subflow_init_req_cookie_join_save(subflow_req, skb);
228 else
229 return -EPERM;
230 }
231
232 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
233 subflow_req->remote_nonce, subflow_req->msk);
234 }
235
236 return 0;
237}
238
239int mptcp_subflow_init_cookie_req(struct request_sock *req,
240 const struct sock *sk_listener,
241 struct sk_buff *skb)
242{
243 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
244 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
245 struct mptcp_options_received mp_opt;
246 int err;
247
248 subflow_init_req(req, sk_listener);
249 mptcp_get_options(sk_listener, skb, &mp_opt);
250
251 if (mp_opt.mp_capable && mp_opt.mp_join)
252 return -EINVAL;
253
254 if (mp_opt.mp_capable && listener->request_mptcp) {
255 if (mp_opt.sndr_key == 0)
256 return -EINVAL;
257
258 subflow_req->local_key = mp_opt.rcvr_key;
259 err = mptcp_token_new_request(req);
260 if (err)
261 return err;
262
263 subflow_req->mp_capable = 1;
264 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
265 } else if (mp_opt.mp_join && listener->request_mptcp) {
266 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
267 return -EINVAL;
268
269 subflow_req->mp_join = 1;
270 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
271 }
272
273 return 0;
274}
275EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
276
277static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
278 struct sk_buff *skb,
279 struct flowi *fl,
280 struct request_sock *req)
281{
282 struct dst_entry *dst;
283 int err;
284
285 tcp_rsk(req)->is_mptcp = 1;
286 subflow_init_req(req, sk);
287
288 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
289 if (!dst)
290 return NULL;
291
292 err = subflow_check_req(req, sk, skb);
293 if (err == 0)
294 return dst;
295
296 dst_release(dst);
297 if (!req->syncookie)
298 tcp_request_sock_ops.send_reset(sk, skb);
299 return NULL;
300}
301
302#if IS_ENABLED(CONFIG_MPTCP_IPV6)
303static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
304 struct sk_buff *skb,
305 struct flowi *fl,
306 struct request_sock *req)
307{
308 struct dst_entry *dst;
309 int err;
310
311 tcp_rsk(req)->is_mptcp = 1;
312 subflow_init_req(req, sk);
313
314 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
315 if (!dst)
316 return NULL;
317
318 err = subflow_check_req(req, sk, skb);
319 if (err == 0)
320 return dst;
321
322 dst_release(dst);
323 if (!req->syncookie)
324 tcp6_request_sock_ops.send_reset(sk, skb);
325 return NULL;
326}
327#endif
328
329/* validate received truncated hmac and create hmac for third ACK */
330static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
331{
332 u8 hmac[SHA256_DIGEST_SIZE];
333 u64 thmac;
334
335 subflow_generate_hmac(subflow->remote_key, subflow->local_key,
336 subflow->remote_nonce, subflow->local_nonce,
337 hmac);
338
339 thmac = get_unaligned_be64(hmac);
340 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
341 subflow, subflow->token,
342 (unsigned long long)thmac,
343 (unsigned long long)subflow->thmac);
344
345 return thmac == subflow->thmac;
346}
347
348void mptcp_subflow_reset(struct sock *ssk)
349{
350 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
351 struct sock *sk = subflow->conn;
352
353 /* must hold: tcp_done() could drop last reference on parent */
354 sock_hold(sk);
355
356 tcp_set_state(ssk, TCP_CLOSE);
357 tcp_send_active_reset(ssk, GFP_ATOMIC);
358 tcp_done(ssk);
359 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
360 schedule_work(&mptcp_sk(sk)->work))
361 return; /* worker will put sk for us */
362
363 sock_put(sk);
364}
365
366static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
367{
368 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
369}
370
371void __mptcp_set_connected(struct sock *sk)
372{
373 if (sk->sk_state == TCP_SYN_SENT) {
374 inet_sk_state_store(sk, TCP_ESTABLISHED);
375 sk->sk_state_change(sk);
376 }
377}
378
379static void mptcp_set_connected(struct sock *sk)
380{
381 mptcp_data_lock(sk);
382 if (!sock_owned_by_user(sk))
383 __mptcp_set_connected(sk);
384 else
385 set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags);
386 mptcp_data_unlock(sk);
387}
388
389static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
390{
391 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
392 struct mptcp_options_received mp_opt;
393 struct sock *parent = subflow->conn;
394
395 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
396
397
398 /* be sure no special action on any packet other than syn-ack */
399 if (subflow->conn_finished)
400 return;
401
402 mptcp_propagate_sndbuf(parent, sk);
403 subflow->rel_write_seq = 1;
404 subflow->conn_finished = 1;
405 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
406 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
407
408 mptcp_get_options(sk, skb, &mp_opt);
409 if (subflow->request_mptcp) {
410 if (!mp_opt.mp_capable) {
411 MPTCP_INC_STATS(sock_net(sk),
412 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
413 mptcp_do_fallback(sk);
414 pr_fallback(mptcp_sk(subflow->conn));
415 goto fallback;
416 }
417
418 if (mp_opt.csum_reqd)
419 WRITE_ONCE(mptcp_sk(parent)->csum_enabled, true);
420 if (mp_opt.deny_join_id0)
421 WRITE_ONCE(mptcp_sk(parent)->pm.remote_deny_join_id0, true);
422 subflow->mp_capable = 1;
423 subflow->can_ack = 1;
424 subflow->remote_key = mp_opt.sndr_key;
425 pr_debug("subflow=%p, remote_key=%llu", subflow,
426 subflow->remote_key);
427 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
428 mptcp_finish_connect(sk);
429 mptcp_set_connected(parent);
430 } else if (subflow->request_join) {
431 u8 hmac[SHA256_DIGEST_SIZE];
432
433 if (!mp_opt.mp_join) {
434 subflow->reset_reason = MPTCP_RST_EMPTCP;
435 goto do_reset;
436 }
437
438 subflow->thmac = mp_opt.thmac;
439 subflow->remote_nonce = mp_opt.nonce;
440 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
441 subflow->thmac, subflow->remote_nonce);
442
443 if (!subflow_thmac_valid(subflow)) {
444 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
445 subflow->reset_reason = MPTCP_RST_EMPTCP;
446 goto do_reset;
447 }
448
449 if (!mptcp_finish_join(sk))
450 goto do_reset;
451
452 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
453 subflow->local_nonce,
454 subflow->remote_nonce,
455 hmac);
456 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
457
458 subflow->mp_join = 1;
459 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
460
461 if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
462 pr_debug("synack inet_dport=%d %d",
463 ntohs(inet_sk(sk)->inet_dport),
464 ntohs(inet_sk(parent)->inet_dport));
465 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
466 }
467 } else if (mptcp_check_fallback(sk)) {
468fallback:
469 mptcp_rcv_space_init(mptcp_sk(parent), sk);
470 mptcp_set_connected(parent);
471 }
472 return;
473
474do_reset:
475 subflow->reset_transient = 0;
476 mptcp_subflow_reset(sk);
477}
478
479struct request_sock_ops mptcp_subflow_request_sock_ops;
480EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops);
481static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
482
483static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
484{
485 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
486
487 pr_debug("subflow=%p", subflow);
488
489 /* Never answer to SYNs sent to broadcast or multicast */
490 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
491 goto drop;
492
493 return tcp_conn_request(&mptcp_subflow_request_sock_ops,
494 &subflow_request_sock_ipv4_ops,
495 sk, skb);
496drop:
497 tcp_listendrop(sk);
498 return 0;
499}
500
501#if IS_ENABLED(CONFIG_MPTCP_IPV6)
502static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
503static struct inet_connection_sock_af_ops subflow_v6_specific;
504static struct inet_connection_sock_af_ops subflow_v6m_specific;
505static struct proto tcpv6_prot_override;
506
507static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
508{
509 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
510
511 pr_debug("subflow=%p", subflow);
512
513 if (skb->protocol == htons(ETH_P_IP))
514 return subflow_v4_conn_request(sk, skb);
515
516 if (!ipv6_unicast_destination(skb))
517 goto drop;
518
519 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
520 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
521 return 0;
522 }
523
524 return tcp_conn_request(&mptcp_subflow_request_sock_ops,
525 &subflow_request_sock_ipv6_ops, sk, skb);
526
527drop:
528 tcp_listendrop(sk);
529 return 0; /* don't send reset */
530}
531#endif
532
533/* validate hmac received in third ACK */
534static bool subflow_hmac_valid(const struct request_sock *req,
535 const struct mptcp_options_received *mp_opt)
536{
537 const struct mptcp_subflow_request_sock *subflow_req;
538 u8 hmac[SHA256_DIGEST_SIZE];
539 struct mptcp_sock *msk;
540
541 subflow_req = mptcp_subflow_rsk(req);
542 msk = subflow_req->msk;
543 if (!msk)
544 return false;
545
546 subflow_generate_hmac(msk->remote_key, msk->local_key,
547 subflow_req->remote_nonce,
548 subflow_req->local_nonce, hmac);
549
550 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
551}
552
553static void mptcp_sock_destruct(struct sock *sk)
554{
555 /* if new mptcp socket isn't accepted, it is free'd
556 * from the tcp listener sockets request queue, linked
557 * from req->sk. The tcp socket is released.
558 * This calls the ULP release function which will
559 * also remove the mptcp socket, via
560 * sock_put(ctx->conn).
561 *
562 * Problem is that the mptcp socket will be in
563 * ESTABLISHED state and will not have the SOCK_DEAD flag.
564 * Both result in warnings from inet_sock_destruct.
565 */
566 if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
567 sk->sk_state = TCP_CLOSE;
568 WARN_ON_ONCE(sk->sk_socket);
569 sock_orphan(sk);
570 }
571
572 mptcp_destroy_common(mptcp_sk(sk));
573 inet_sock_destruct(sk);
574}
575
576static void mptcp_force_close(struct sock *sk)
577{
578 /* the msk is not yet exposed to user-space */
579 inet_sk_state_store(sk, TCP_CLOSE);
580 sk_common_release(sk);
581}
582
583static void subflow_ulp_fallback(struct sock *sk,
584 struct mptcp_subflow_context *old_ctx)
585{
586 struct inet_connection_sock *icsk = inet_csk(sk);
587
588 mptcp_subflow_tcp_fallback(sk, old_ctx);
589 icsk->icsk_ulp_ops = NULL;
590 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
591 tcp_sk(sk)->is_mptcp = 0;
592
593 mptcp_subflow_ops_undo_override(sk);
594}
595
596static void subflow_drop_ctx(struct sock *ssk)
597{
598 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
599
600 if (!ctx)
601 return;
602
603 subflow_ulp_fallback(ssk, ctx);
604 if (ctx->conn)
605 sock_put(ctx->conn);
606
607 kfree_rcu(ctx, rcu);
608}
609
610void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
611 struct mptcp_options_received *mp_opt)
612{
613 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
614
615 subflow->remote_key = mp_opt->sndr_key;
616 subflow->fully_established = 1;
617 subflow->can_ack = 1;
618 WRITE_ONCE(msk->fully_established, true);
619}
620
621static struct sock *subflow_syn_recv_sock(const struct sock *sk,
622 struct sk_buff *skb,
623 struct request_sock *req,
624 struct dst_entry *dst,
625 struct request_sock *req_unhash,
626 bool *own_req)
627{
628 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
629 struct mptcp_subflow_request_sock *subflow_req;
630 struct mptcp_options_received mp_opt;
631 bool fallback, fallback_is_fatal;
632 struct sock *new_msk = NULL;
633 struct sock *child;
634
635 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
636
637 /* After child creation we must look for 'mp_capable' even when options
638 * are not parsed
639 */
640 mp_opt.mp_capable = 0;
641
642 /* hopefully temporary handling for MP_JOIN+syncookie */
643 subflow_req = mptcp_subflow_rsk(req);
644 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
645 fallback = !tcp_rsk(req)->is_mptcp;
646 if (fallback)
647 goto create_child;
648
649 /* if the sk is MP_CAPABLE, we try to fetch the client key */
650 if (subflow_req->mp_capable) {
651 /* we can receive and accept an in-window, out-of-order pkt,
652 * which may not carry the MP_CAPABLE opt even on mptcp enabled
653 * paths: always try to extract the peer key, and fallback
654 * for packets missing it.
655 * Even OoO DSS packets coming legitly after dropped or
656 * reordered MPC will cause fallback, but we don't have other
657 * options.
658 */
659 mptcp_get_options(sk, skb, &mp_opt);
660 if (!mp_opt.mp_capable) {
661 fallback = true;
662 goto create_child;
663 }
664
665 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
666 if (!new_msk)
667 fallback = true;
668 } else if (subflow_req->mp_join) {
669 mptcp_get_options(sk, skb, &mp_opt);
670 if (!mp_opt.mp_join || !subflow_hmac_valid(req, &mp_opt) ||
671 !mptcp_can_accept_new_subflow(subflow_req->msk)) {
672 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
673 fallback = true;
674 }
675 }
676
677create_child:
678 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
679 req_unhash, own_req);
680
681 if (child && *own_req) {
682 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
683
684 tcp_rsk(req)->drop_req = false;
685
686 /* we need to fallback on ctx allocation failure and on pre-reqs
687 * checking above. In the latter scenario we additionally need
688 * to reset the context to non MPTCP status.
689 */
690 if (!ctx || fallback) {
691 if (fallback_is_fatal) {
692 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
693 goto dispose_child;
694 }
695
696 subflow_drop_ctx(child);
697 goto out;
698 }
699
700 /* ssk inherits options of listener sk */
701 ctx->setsockopt_seq = listener->setsockopt_seq;
702
703 if (ctx->mp_capable) {
704 /* this can't race with mptcp_close(), as the msk is
705 * not yet exposted to user-space
706 */
707 inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
708
709 /* record the newly created socket as the first msk
710 * subflow, but don't link it yet into conn_list
711 */
712 WRITE_ONCE(mptcp_sk(new_msk)->first, child);
713
714 /* new mpc subflow takes ownership of the newly
715 * created mptcp socket
716 */
717 new_msk->sk_destruct = mptcp_sock_destruct;
718 mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
719 mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
720 mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
721 ctx->conn = new_msk;
722 new_msk = NULL;
723
724 /* with OoO packets we can reach here without ingress
725 * mpc option
726 */
727 if (mp_opt.mp_capable)
728 mptcp_subflow_fully_established(ctx, &mp_opt);
729 } else if (ctx->mp_join) {
730 struct mptcp_sock *owner;
731
732 owner = subflow_req->msk;
733 if (!owner) {
734 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
735 goto dispose_child;
736 }
737
738 /* move the msk reference ownership to the subflow */
739 subflow_req->msk = NULL;
740 ctx->conn = (struct sock *)owner;
741
742 if (subflow_use_different_sport(owner, sk)) {
743 pr_debug("ack inet_sport=%d %d",
744 ntohs(inet_sk(sk)->inet_sport),
745 ntohs(inet_sk((struct sock *)owner)->inet_sport));
746 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
747 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
748 goto dispose_child;
749 }
750 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
751 }
752
753 if (!mptcp_finish_join(child))
754 goto dispose_child;
755
756 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
757 tcp_rsk(req)->drop_req = true;
758 }
759 }
760
761out:
762 /* dispose of the left over mptcp master, if any */
763 if (unlikely(new_msk))
764 mptcp_force_close(new_msk);
765
766 /* check for expected invariant - should never trigger, just help
767 * catching eariler subtle bugs
768 */
769 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
770 (!mptcp_subflow_ctx(child) ||
771 !mptcp_subflow_ctx(child)->conn));
772 return child;
773
774dispose_child:
775 subflow_drop_ctx(child);
776 tcp_rsk(req)->drop_req = true;
777 inet_csk_prepare_for_destroy_sock(child);
778 tcp_done(child);
779 req->rsk_ops->send_reset(sk, skb);
780
781 /* The last child reference will be released by the caller */
782 return child;
783}
784
785static struct inet_connection_sock_af_ops subflow_specific;
786static struct proto tcp_prot_override;
787
788enum mapping_status {
789 MAPPING_OK,
790 MAPPING_INVALID,
791 MAPPING_EMPTY,
792 MAPPING_DATA_FIN,
793 MAPPING_DUMMY
794};
795
796static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
797{
798 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
799 ssn, subflow->map_subflow_seq, subflow->map_data_len);
800}
801
802static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
803{
804 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
805 unsigned int skb_consumed;
806
807 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
808 if (WARN_ON_ONCE(skb_consumed >= skb->len))
809 return true;
810
811 return skb->len - skb_consumed <= subflow->map_data_len -
812 mptcp_subflow_get_map_offset(subflow);
813}
814
815static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
816{
817 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
818 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
819
820 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
821 /* Mapping covers data later in the subflow stream,
822 * currently unsupported.
823 */
824 dbg_bad_map(subflow, ssn);
825 return false;
826 }
827 if (unlikely(!before(ssn, subflow->map_subflow_seq +
828 subflow->map_data_len))) {
829 /* Mapping does covers past subflow data, invalid */
830 dbg_bad_map(subflow, ssn);
831 return false;
832 }
833 return true;
834}
835
836static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
837 bool csum_reqd)
838{
839 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
840 struct csum_pseudo_header header;
841 u32 offset, seq, delta;
842 __wsum csum;
843 int len;
844
845 if (!csum_reqd)
846 return MAPPING_OK;
847
848 /* mapping already validated on previous traversal */
849 if (subflow->map_csum_len == subflow->map_data_len)
850 return MAPPING_OK;
851
852 /* traverse the receive queue, ensuring it contains a full
853 * DSS mapping and accumulating the related csum.
854 * Preserve the accoumlate csum across multiple calls, to compute
855 * the csum only once
856 */
857 delta = subflow->map_data_len - subflow->map_csum_len;
858 for (;;) {
859 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
860 offset = seq - TCP_SKB_CB(skb)->seq;
861
862 /* if the current skb has not been accounted yet, csum its contents
863 * up to the amount covered by the current DSS
864 */
865 if (offset < skb->len) {
866 __wsum csum;
867
868 len = min(skb->len - offset, delta);
869 csum = skb_checksum(skb, offset, len, 0);
870 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
871 subflow->map_csum_len);
872
873 delta -= len;
874 subflow->map_csum_len += len;
875 }
876 if (delta == 0)
877 break;
878
879 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
880 /* if this subflow is closed, the partial mapping
881 * will be never completed; flush the pending skbs, so
882 * that subflow_sched_work_if_closed() can kick in
883 */
884 if (unlikely(ssk->sk_state == TCP_CLOSE))
885 while ((skb = skb_peek(&ssk->sk_receive_queue)))
886 sk_eat_skb(ssk, skb);
887
888 /* not enough data to validate the csum */
889 return MAPPING_EMPTY;
890 }
891
892 /* the DSS mapping for next skbs will be validated later,
893 * when a get_mapping_status call will process such skb
894 */
895 skb = skb->next;
896 }
897
898 /* note that 'map_data_len' accounts only for the carried data, does
899 * not include the eventual seq increment due to the data fin,
900 * while the pseudo header requires the original DSS data len,
901 * including that
902 */
903 header.data_seq = cpu_to_be64(subflow->map_seq);
904 header.subflow_seq = htonl(subflow->map_subflow_seq);
905 header.data_len = htons(subflow->map_data_len + subflow->map_data_fin);
906 header.csum = 0;
907
908 csum = csum_partial(&header, sizeof(header), subflow->map_data_csum);
909 if (unlikely(csum_fold(csum))) {
910 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
911 return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
912 }
913
914 return MAPPING_OK;
915}
916
917static enum mapping_status get_mapping_status(struct sock *ssk,
918 struct mptcp_sock *msk)
919{
920 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
921 bool csum_reqd = READ_ONCE(msk->csum_enabled);
922 struct mptcp_ext *mpext;
923 struct sk_buff *skb;
924 u16 data_len;
925 u64 map_seq;
926
927 skb = skb_peek(&ssk->sk_receive_queue);
928 if (!skb)
929 return MAPPING_EMPTY;
930
931 if (mptcp_check_fallback(ssk))
932 return MAPPING_DUMMY;
933
934 mpext = mptcp_get_ext(skb);
935 if (!mpext || !mpext->use_map) {
936 if (!subflow->map_valid && !skb->len) {
937 /* the TCP stack deliver 0 len FIN pkt to the receive
938 * queue, that is the only 0len pkts ever expected here,
939 * and we can admit no mapping only for 0 len pkts
940 */
941 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
942 WARN_ONCE(1, "0len seq %d:%d flags %x",
943 TCP_SKB_CB(skb)->seq,
944 TCP_SKB_CB(skb)->end_seq,
945 TCP_SKB_CB(skb)->tcp_flags);
946 sk_eat_skb(ssk, skb);
947 return MAPPING_EMPTY;
948 }
949
950 if (!subflow->map_valid)
951 return MAPPING_INVALID;
952
953 goto validate_seq;
954 }
955
956 trace_get_mapping_status(mpext);
957
958 data_len = mpext->data_len;
959 if (data_len == 0) {
960 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
961 return MAPPING_INVALID;
962 }
963
964 if (mpext->data_fin == 1) {
965 if (data_len == 1) {
966 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
967 mpext->dsn64);
968 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
969 if (subflow->map_valid) {
970 /* A DATA_FIN might arrive in a DSS
971 * option before the previous mapping
972 * has been fully consumed. Continue
973 * handling the existing mapping.
974 */
975 skb_ext_del(skb, SKB_EXT_MPTCP);
976 return MAPPING_OK;
977 } else {
978 if (updated && schedule_work(&msk->work))
979 sock_hold((struct sock *)msk);
980
981 return MAPPING_DATA_FIN;
982 }
983 } else {
984 u64 data_fin_seq = mpext->data_seq + data_len - 1;
985
986 /* If mpext->data_seq is a 32-bit value, data_fin_seq
987 * must also be limited to 32 bits.
988 */
989 if (!mpext->dsn64)
990 data_fin_seq &= GENMASK_ULL(31, 0);
991
992 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
993 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
994 data_fin_seq, mpext->dsn64);
995 }
996
997 /* Adjust for DATA_FIN using 1 byte of sequence space */
998 data_len--;
999 }
1000
1001 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1002 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1003
1004 if (subflow->map_valid) {
1005 /* Allow replacing only with an identical map */
1006 if (subflow->map_seq == map_seq &&
1007 subflow->map_subflow_seq == mpext->subflow_seq &&
1008 subflow->map_data_len == data_len &&
1009 subflow->map_csum_reqd == mpext->csum_reqd) {
1010 skb_ext_del(skb, SKB_EXT_MPTCP);
1011 goto validate_csum;
1012 }
1013
1014 /* If this skb data are fully covered by the current mapping,
1015 * the new map would need caching, which is not supported
1016 */
1017 if (skb_is_fully_mapped(ssk, skb)) {
1018 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1019 return MAPPING_INVALID;
1020 }
1021
1022 /* will validate the next map after consuming the current one */
1023 goto validate_csum;
1024 }
1025
1026 subflow->map_seq = map_seq;
1027 subflow->map_subflow_seq = mpext->subflow_seq;
1028 subflow->map_data_len = data_len;
1029 subflow->map_valid = 1;
1030 subflow->map_data_fin = mpext->data_fin;
1031 subflow->mpc_map = mpext->mpc_map;
1032 subflow->map_csum_reqd = mpext->csum_reqd;
1033 subflow->map_csum_len = 0;
1034 subflow->map_data_csum = csum_unfold(mpext->csum);
1035
1036 /* Cfr RFC 8684 Section 3.3.0 */
1037 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1038 return MAPPING_INVALID;
1039
1040 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1041 subflow->map_seq, subflow->map_subflow_seq,
1042 subflow->map_data_len, subflow->map_csum_reqd,
1043 subflow->map_data_csum);
1044
1045validate_seq:
1046 /* we revalidate valid mapping on new skb, because we must ensure
1047 * the current skb is completely covered by the available mapping
1048 */
1049 if (!validate_mapping(ssk, skb)) {
1050 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1051 return MAPPING_INVALID;
1052 }
1053
1054 skb_ext_del(skb, SKB_EXT_MPTCP);
1055
1056validate_csum:
1057 return validate_data_csum(ssk, skb, csum_reqd);
1058}
1059
1060static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1061 u64 limit)
1062{
1063 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1064 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1065 u32 incr;
1066
1067 incr = limit >= skb->len ? skb->len + fin : limit;
1068
1069 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1070 subflow->map_subflow_seq);
1071 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1072 tcp_sk(ssk)->copied_seq += incr;
1073 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1074 sk_eat_skb(ssk, skb);
1075 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1076 subflow->map_valid = 0;
1077}
1078
1079/* sched mptcp worker to remove the subflow if no more data is pending */
1080static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1081{
1082 struct sock *sk = (struct sock *)msk;
1083
1084 if (likely(ssk->sk_state != TCP_CLOSE))
1085 return;
1086
1087 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1088 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
1089 sock_hold(sk);
1090 if (!schedule_work(&msk->work))
1091 sock_put(sk);
1092 }
1093}
1094
1095static bool subflow_check_data_avail(struct sock *ssk)
1096{
1097 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1098 enum mapping_status status;
1099 struct mptcp_sock *msk;
1100 struct sk_buff *skb;
1101
1102 if (!skb_peek(&ssk->sk_receive_queue))
1103 WRITE_ONCE(subflow->data_avail, 0);
1104 if (subflow->data_avail)
1105 return true;
1106
1107 msk = mptcp_sk(subflow->conn);
1108 for (;;) {
1109 u64 ack_seq;
1110 u64 old_ack;
1111
1112 status = get_mapping_status(ssk, msk);
1113 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1114 if (unlikely(status == MAPPING_INVALID))
1115 goto fallback;
1116
1117 if (unlikely(status == MAPPING_DUMMY))
1118 goto fallback;
1119
1120 if (status != MAPPING_OK)
1121 goto no_data;
1122
1123 skb = skb_peek(&ssk->sk_receive_queue);
1124 if (WARN_ON_ONCE(!skb))
1125 goto no_data;
1126
1127 /* if msk lacks the remote key, this subflow must provide an
1128 * MP_CAPABLE-based mapping
1129 */
1130 if (unlikely(!READ_ONCE(msk->can_ack))) {
1131 if (!subflow->mpc_map)
1132 goto fallback;
1133 WRITE_ONCE(msk->remote_key, subflow->remote_key);
1134 WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1135 WRITE_ONCE(msk->can_ack, true);
1136 }
1137
1138 old_ack = READ_ONCE(msk->ack_seq);
1139 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1140 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1141 ack_seq);
1142 if (unlikely(before64(ack_seq, old_ack))) {
1143 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1144 continue;
1145 }
1146
1147 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1148 break;
1149 }
1150 return true;
1151
1152no_data:
1153 subflow_sched_work_if_closed(msk, ssk);
1154 return false;
1155
1156fallback:
1157 /* RFC 8684 section 3.7. */
1158 if (subflow->mp_join || subflow->fully_established) {
1159 /* fatal protocol error, close the socket.
1160 * subflow_error_report() will introduce the appropriate barriers
1161 */
1162 ssk->sk_err = EBADMSG;
1163 tcp_set_state(ssk, TCP_CLOSE);
1164 subflow->reset_transient = 0;
1165 subflow->reset_reason = MPTCP_RST_EMPTCP;
1166 tcp_send_active_reset(ssk, GFP_ATOMIC);
1167 WRITE_ONCE(subflow->data_avail, 0);
1168 return false;
1169 }
1170
1171 __mptcp_do_fallback(msk);
1172 skb = skb_peek(&ssk->sk_receive_queue);
1173 subflow->map_valid = 1;
1174 subflow->map_seq = READ_ONCE(msk->ack_seq);
1175 subflow->map_data_len = skb->len;
1176 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1177 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1178 return true;
1179}
1180
1181bool mptcp_subflow_data_available(struct sock *sk)
1182{
1183 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1184
1185 /* check if current mapping is still valid */
1186 if (subflow->map_valid &&
1187 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1188 subflow->map_valid = 0;
1189 WRITE_ONCE(subflow->data_avail, 0);
1190
1191 pr_debug("Done with mapping: seq=%u data_len=%u",
1192 subflow->map_subflow_seq,
1193 subflow->map_data_len);
1194 }
1195
1196 return subflow_check_data_avail(sk);
1197}
1198
1199/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1200 * not the ssk one.
1201 *
1202 * In mptcp, rwin is about the mptcp-level connection data.
1203 *
1204 * Data that is still on the ssk rx queue can thus be ignored,
1205 * as far as mptcp peer is concerned that data is still inflight.
1206 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1207 */
1208void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1209{
1210 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1211 const struct sock *sk = subflow->conn;
1212
1213 *space = __mptcp_space(sk);
1214 *full_space = tcp_full_space(sk);
1215}
1216
1217void __mptcp_error_report(struct sock *sk)
1218{
1219 struct mptcp_subflow_context *subflow;
1220 struct mptcp_sock *msk = mptcp_sk(sk);
1221
1222 mptcp_for_each_subflow(msk, subflow) {
1223 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1224 int err = sock_error(ssk);
1225
1226 if (!err)
1227 continue;
1228
1229 /* only propagate errors on fallen-back sockets or
1230 * on MPC connect
1231 */
1232 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1233 continue;
1234
1235 inet_sk_state_store(sk, inet_sk_state_load(ssk));
1236 sk->sk_err = -err;
1237
1238 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1239 smp_wmb();
1240 sk_error_report(sk);
1241 break;
1242 }
1243}
1244
1245static void subflow_error_report(struct sock *ssk)
1246{
1247 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1248
1249 mptcp_data_lock(sk);
1250 if (!sock_owned_by_user(sk))
1251 __mptcp_error_report(sk);
1252 else
1253 set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->flags);
1254 mptcp_data_unlock(sk);
1255}
1256
1257static void subflow_data_ready(struct sock *sk)
1258{
1259 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1260 u16 state = 1 << inet_sk_state_load(sk);
1261 struct sock *parent = subflow->conn;
1262 struct mptcp_sock *msk;
1263
1264 msk = mptcp_sk(parent);
1265 if (state & TCPF_LISTEN) {
1266 /* MPJ subflow are removed from accept queue before reaching here,
1267 * avoid stray wakeups
1268 */
1269 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1270 return;
1271
1272 set_bit(MPTCP_DATA_READY, &msk->flags);
1273 parent->sk_data_ready(parent);
1274 return;
1275 }
1276
1277 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1278 !subflow->mp_join && !(state & TCPF_CLOSE));
1279
1280 if (mptcp_subflow_data_available(sk))
1281 mptcp_data_ready(parent, sk);
1282 else if (unlikely(sk->sk_err))
1283 subflow_error_report(sk);
1284}
1285
1286static void subflow_write_space(struct sock *ssk)
1287{
1288 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1289
1290 mptcp_propagate_sndbuf(sk, ssk);
1291 mptcp_write_space(sk);
1292}
1293
1294static struct inet_connection_sock_af_ops *
1295subflow_default_af_ops(struct sock *sk)
1296{
1297#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1298 if (sk->sk_family == AF_INET6)
1299 return &subflow_v6_specific;
1300#endif
1301 return &subflow_specific;
1302}
1303
1304#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1305void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1306{
1307 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1308 struct inet_connection_sock *icsk = inet_csk(sk);
1309 struct inet_connection_sock_af_ops *target;
1310
1311 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1312
1313 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1314 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1315
1316 if (likely(icsk->icsk_af_ops == target))
1317 return;
1318
1319 subflow->icsk_af_ops = icsk->icsk_af_ops;
1320 icsk->icsk_af_ops = target;
1321}
1322#endif
1323
1324void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1325 struct sockaddr_storage *addr,
1326 unsigned short family)
1327{
1328 memset(addr, 0, sizeof(*addr));
1329 addr->ss_family = family;
1330 if (addr->ss_family == AF_INET) {
1331 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1332
1333 if (info->family == AF_INET)
1334 in_addr->sin_addr = info->addr;
1335#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1336 else if (ipv6_addr_v4mapped(&info->addr6))
1337 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1338#endif
1339 in_addr->sin_port = info->port;
1340 }
1341#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1342 else if (addr->ss_family == AF_INET6) {
1343 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1344
1345 if (info->family == AF_INET)
1346 ipv6_addr_set_v4mapped(info->addr.s_addr,
1347 &in6_addr->sin6_addr);
1348 else
1349 in6_addr->sin6_addr = info->addr6;
1350 in6_addr->sin6_port = info->port;
1351 }
1352#endif
1353}
1354
1355int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1356 const struct mptcp_addr_info *remote,
1357 u8 flags, int ifindex)
1358{
1359 struct mptcp_sock *msk = mptcp_sk(sk);
1360 struct mptcp_subflow_context *subflow;
1361 struct sockaddr_storage addr;
1362 int remote_id = remote->id;
1363 int local_id = loc->id;
1364 struct socket *sf;
1365 struct sock *ssk;
1366 u32 remote_token;
1367 int addrlen;
1368 int err;
1369
1370 if (!mptcp_is_fully_established(sk))
1371 return -ENOTCONN;
1372
1373 err = mptcp_subflow_create_socket(sk, &sf);
1374 if (err)
1375 return err;
1376
1377 ssk = sf->sk;
1378 subflow = mptcp_subflow_ctx(ssk);
1379 do {
1380 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1381 } while (!subflow->local_nonce);
1382
1383 if (!local_id) {
1384 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
1385 if (err < 0)
1386 goto failed;
1387
1388 local_id = err;
1389 }
1390
1391 subflow->remote_key = msk->remote_key;
1392 subflow->local_key = msk->local_key;
1393 subflow->token = msk->token;
1394 mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1395
1396 addrlen = sizeof(struct sockaddr_in);
1397#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1398 if (addr.ss_family == AF_INET6)
1399 addrlen = sizeof(struct sockaddr_in6);
1400#endif
1401 ssk->sk_bound_dev_if = ifindex;
1402 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1403 if (err)
1404 goto failed;
1405
1406 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1407 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1408 remote_token, local_id, remote_id);
1409 subflow->remote_token = remote_token;
1410 subflow->local_id = local_id;
1411 subflow->remote_id = remote_id;
1412 subflow->request_join = 1;
1413 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1414 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1415
1416 mptcp_add_pending_subflow(msk, subflow);
1417 mptcp_sockopt_sync(msk, ssk);
1418 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1419 if (err && err != -EINPROGRESS)
1420 goto failed_unlink;
1421
1422 /* discard the subflow socket */
1423 mptcp_sock_graft(ssk, sk->sk_socket);
1424 iput(SOCK_INODE(sf));
1425 return err;
1426
1427failed_unlink:
1428 spin_lock_bh(&msk->join_list_lock);
1429 list_del(&subflow->node);
1430 spin_unlock_bh(&msk->join_list_lock);
1431 sock_put(mptcp_subflow_tcp_sock(subflow));
1432
1433failed:
1434 subflow->disposable = 1;
1435 sock_release(sf);
1436 return err;
1437}
1438
1439static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1440{
1441#ifdef CONFIG_SOCK_CGROUP_DATA
1442 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1443 *child_skcd = &child->sk_cgrp_data;
1444
1445 /* only the additional subflows created by kworkers have to be modified */
1446 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1447 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1448#ifdef CONFIG_MEMCG
1449 struct mem_cgroup *memcg = parent->sk_memcg;
1450
1451 mem_cgroup_sk_free(child);
1452 if (memcg && css_tryget(&memcg->css))
1453 child->sk_memcg = memcg;
1454#endif /* CONFIG_MEMCG */
1455
1456 cgroup_sk_free(child_skcd);
1457 *child_skcd = *parent_skcd;
1458 cgroup_sk_clone(child_skcd);
1459 }
1460#endif /* CONFIG_SOCK_CGROUP_DATA */
1461}
1462
1463static void mptcp_subflow_ops_override(struct sock *ssk)
1464{
1465#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1466 if (ssk->sk_prot == &tcpv6_prot)
1467 ssk->sk_prot = &tcpv6_prot_override;
1468 else
1469#endif
1470 ssk->sk_prot = &tcp_prot_override;
1471}
1472
1473static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1474{
1475#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1476 if (ssk->sk_prot == &tcpv6_prot_override)
1477 ssk->sk_prot = &tcpv6_prot;
1478 else
1479#endif
1480 ssk->sk_prot = &tcp_prot;
1481}
1482int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
1483{
1484 struct mptcp_subflow_context *subflow;
1485 struct net *net = sock_net(sk);
1486 struct socket *sf;
1487 int err;
1488
1489 /* un-accepted server sockets can reach here - on bad configuration
1490 * bail early to avoid greater trouble later
1491 */
1492 if (unlikely(!sk->sk_socket))
1493 return -EINVAL;
1494
1495 err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
1496 &sf);
1497 if (err)
1498 return err;
1499
1500 lock_sock(sf->sk);
1501
1502 /* the newly created socket has to be in the same cgroup as its parent */
1503 mptcp_attach_cgroup(sk, sf->sk);
1504
1505 /* kernel sockets do not by default acquire net ref, but TCP timer
1506 * needs it.
1507 */
1508 sf->sk->sk_net_refcnt = 1;
1509 get_net(net);
1510#ifdef CONFIG_PROC_FS
1511 this_cpu_add(*net->core.sock_inuse, 1);
1512#endif
1513 err = tcp_set_ulp(sf->sk, "mptcp");
1514 release_sock(sf->sk);
1515
1516 if (err) {
1517 sock_release(sf);
1518 return err;
1519 }
1520
1521 /* the newly created socket really belongs to the owning MPTCP master
1522 * socket, even if for additional subflows the allocation is performed
1523 * by a kernel workqueue. Adjust inode references, so that the
1524 * procfs/diag interaces really show this one belonging to the correct
1525 * user.
1526 */
1527 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1528 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1529 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1530
1531 subflow = mptcp_subflow_ctx(sf->sk);
1532 pr_debug("subflow=%p", subflow);
1533
1534 *new_sock = sf;
1535 sock_hold(sk);
1536 subflow->conn = sk;
1537 mptcp_subflow_ops_override(sf->sk);
1538
1539 return 0;
1540}
1541
1542static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1543 gfp_t priority)
1544{
1545 struct inet_connection_sock *icsk = inet_csk(sk);
1546 struct mptcp_subflow_context *ctx;
1547
1548 ctx = kzalloc(sizeof(*ctx), priority);
1549 if (!ctx)
1550 return NULL;
1551
1552 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1553 INIT_LIST_HEAD(&ctx->node);
1554 INIT_LIST_HEAD(&ctx->delegated_node);
1555
1556 pr_debug("subflow=%p", ctx);
1557
1558 ctx->tcp_sock = sk;
1559
1560 return ctx;
1561}
1562
1563static void __subflow_state_change(struct sock *sk)
1564{
1565 struct socket_wq *wq;
1566
1567 rcu_read_lock();
1568 wq = rcu_dereference(sk->sk_wq);
1569 if (skwq_has_sleeper(wq))
1570 wake_up_interruptible_all(&wq->wait);
1571 rcu_read_unlock();
1572}
1573
1574static bool subflow_is_done(const struct sock *sk)
1575{
1576 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1577}
1578
1579static void subflow_state_change(struct sock *sk)
1580{
1581 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1582 struct sock *parent = subflow->conn;
1583
1584 __subflow_state_change(sk);
1585
1586 if (subflow_simultaneous_connect(sk)) {
1587 mptcp_propagate_sndbuf(parent, sk);
1588 mptcp_do_fallback(sk);
1589 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1590 pr_fallback(mptcp_sk(parent));
1591 subflow->conn_finished = 1;
1592 mptcp_set_connected(parent);
1593 }
1594
1595 /* as recvmsg() does not acquire the subflow socket for ssk selection
1596 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1597 * the data available machinery here.
1598 */
1599 if (mptcp_subflow_data_available(sk))
1600 mptcp_data_ready(parent, sk);
1601 else if (unlikely(sk->sk_err))
1602 subflow_error_report(sk);
1603
1604 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1605
1606 if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1607 !subflow->rx_eof && subflow_is_done(sk)) {
1608 subflow->rx_eof = 1;
1609 mptcp_subflow_eof(parent);
1610 }
1611}
1612
1613static int subflow_ulp_init(struct sock *sk)
1614{
1615 struct inet_connection_sock *icsk = inet_csk(sk);
1616 struct mptcp_subflow_context *ctx;
1617 struct tcp_sock *tp = tcp_sk(sk);
1618 int err = 0;
1619
1620 /* disallow attaching ULP to a socket unless it has been
1621 * created with sock_create_kern()
1622 */
1623 if (!sk->sk_kern_sock) {
1624 err = -EOPNOTSUPP;
1625 goto out;
1626 }
1627
1628 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1629 if (!ctx) {
1630 err = -ENOMEM;
1631 goto out;
1632 }
1633
1634 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1635
1636 tp->is_mptcp = 1;
1637 ctx->icsk_af_ops = icsk->icsk_af_ops;
1638 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1639 ctx->tcp_data_ready = sk->sk_data_ready;
1640 ctx->tcp_state_change = sk->sk_state_change;
1641 ctx->tcp_write_space = sk->sk_write_space;
1642 ctx->tcp_error_report = sk->sk_error_report;
1643 sk->sk_data_ready = subflow_data_ready;
1644 sk->sk_write_space = subflow_write_space;
1645 sk->sk_state_change = subflow_state_change;
1646 sk->sk_error_report = subflow_error_report;
1647out:
1648 return err;
1649}
1650
1651static void subflow_ulp_release(struct sock *ssk)
1652{
1653 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1654 bool release = true;
1655 struct sock *sk;
1656
1657 if (!ctx)
1658 return;
1659
1660 sk = ctx->conn;
1661 if (sk) {
1662 /* if the msk has been orphaned, keep the ctx
1663 * alive, will be freed by __mptcp_close_ssk(),
1664 * when the subflow is still unaccepted
1665 */
1666 release = ctx->disposable || list_empty(&ctx->node);
1667 sock_put(sk);
1668 }
1669
1670 mptcp_subflow_ops_undo_override(ssk);
1671 if (release)
1672 kfree_rcu(ctx, rcu);
1673}
1674
1675static void subflow_ulp_clone(const struct request_sock *req,
1676 struct sock *newsk,
1677 const gfp_t priority)
1678{
1679 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1680 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1681 struct mptcp_subflow_context *new_ctx;
1682
1683 if (!tcp_rsk(req)->is_mptcp ||
1684 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1685 subflow_ulp_fallback(newsk, old_ctx);
1686 return;
1687 }
1688
1689 new_ctx = subflow_create_ctx(newsk, priority);
1690 if (!new_ctx) {
1691 subflow_ulp_fallback(newsk, old_ctx);
1692 return;
1693 }
1694
1695 new_ctx->conn_finished = 1;
1696 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1697 new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
1698 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1699 new_ctx->tcp_write_space = old_ctx->tcp_write_space;
1700 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1701 new_ctx->rel_write_seq = 1;
1702 new_ctx->tcp_sock = newsk;
1703
1704 if (subflow_req->mp_capable) {
1705 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1706 * is fully established only after we receive the remote key
1707 */
1708 new_ctx->mp_capable = 1;
1709 new_ctx->local_key = subflow_req->local_key;
1710 new_ctx->token = subflow_req->token;
1711 new_ctx->ssn_offset = subflow_req->ssn_offset;
1712 new_ctx->idsn = subflow_req->idsn;
1713 } else if (subflow_req->mp_join) {
1714 new_ctx->ssn_offset = subflow_req->ssn_offset;
1715 new_ctx->mp_join = 1;
1716 new_ctx->fully_established = 1;
1717 new_ctx->backup = subflow_req->backup;
1718 new_ctx->local_id = subflow_req->local_id;
1719 new_ctx->remote_id = subflow_req->remote_id;
1720 new_ctx->token = subflow_req->token;
1721 new_ctx->thmac = subflow_req->thmac;
1722 }
1723}
1724
1725static void tcp_release_cb_override(struct sock *ssk)
1726{
1727 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1728
1729 if (mptcp_subflow_has_delegated_action(subflow))
1730 mptcp_subflow_process_delegated(ssk);
1731
1732 tcp_release_cb(ssk);
1733}
1734
1735static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1736 .name = "mptcp",
1737 .owner = THIS_MODULE,
1738 .init = subflow_ulp_init,
1739 .release = subflow_ulp_release,
1740 .clone = subflow_ulp_clone,
1741};
1742
1743static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1744{
1745 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1746 subflow_ops->slab_name = "request_sock_subflow";
1747
1748 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1749 subflow_ops->obj_size, 0,
1750 SLAB_ACCOUNT |
1751 SLAB_TYPESAFE_BY_RCU,
1752 NULL);
1753 if (!subflow_ops->slab)
1754 return -ENOMEM;
1755
1756 subflow_ops->destructor = subflow_req_destructor;
1757
1758 return 0;
1759}
1760
1761void __init mptcp_subflow_init(void)
1762{
1763 mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
1764 if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
1765 panic("MPTCP: failed to init subflow request sock ops\n");
1766
1767 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1768 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1769
1770 subflow_specific = ipv4_specific;
1771 subflow_specific.conn_request = subflow_v4_conn_request;
1772 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1773 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1774
1775 tcp_prot_override = tcp_prot;
1776 tcp_prot_override.release_cb = tcp_release_cb_override;
1777
1778#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1779 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1780 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1781
1782 subflow_v6_specific = ipv6_specific;
1783 subflow_v6_specific.conn_request = subflow_v6_conn_request;
1784 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1785 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1786
1787 subflow_v6m_specific = subflow_v6_specific;
1788 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1789 subflow_v6m_specific.send_check = ipv4_specific.send_check;
1790 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1791 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1792 subflow_v6m_specific.net_frag_header_len = 0;
1793
1794 tcpv6_prot_override = tcpv6_prot;
1795 tcpv6_prot_override.release_cb = tcp_release_cb_override;
1796#endif
1797
1798 mptcp_diag_subflow_init(&subflow_ulp_ops);
1799
1800 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1801 panic("MPTCP: failed to register subflows to ULP\n");
1802}
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#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#include <trace/events/sock.h>
30
31static void mptcp_subflow_ops_undo_override(struct sock *ssk);
32
33static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
34 enum linux_mptcp_mib_field field)
35{
36 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
37}
38
39static void subflow_req_destructor(struct request_sock *req)
40{
41 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
42
43 pr_debug("subflow_req=%p", subflow_req);
44
45 if (subflow_req->msk)
46 sock_put((struct sock *)subflow_req->msk);
47
48 mptcp_token_destroy_request(req);
49}
50
51static 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
62static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
63{
64 return mptcp_is_fully_established((void *)msk) &&
65 ((mptcp_pm_is_userspace(msk) &&
66 mptcp_userspace_pm_active(msk)) ||
67 READ_ONCE(msk->pm.accept_subflow));
68}
69
70/* validate received token and create truncated hmac and nonce for SYN-ACK */
71static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
72{
73 struct mptcp_sock *msk = subflow_req->msk;
74 u8 hmac[SHA256_DIGEST_SIZE];
75
76 get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
77
78 subflow_generate_hmac(msk->local_key, 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
104 return msk;
105}
106
107static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
108{
109 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
110
111 subflow_req->mp_capable = 0;
112 subflow_req->mp_join = 0;
113 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
114 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
115 subflow_req->msk = NULL;
116 mptcp_token_init_request(req);
117}
118
119static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
120{
121 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
122}
123
124static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
125{
126 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
127
128 if (mpext) {
129 memset(mpext, 0, sizeof(*mpext));
130 mpext->reset_reason = reason;
131 }
132}
133
134/* Init mptcp request socket.
135 *
136 * Returns an error code if a JOIN has failed and a TCP reset
137 * should be sent.
138 */
139static int subflow_check_req(struct request_sock *req,
140 const struct sock *sk_listener,
141 struct sk_buff *skb)
142{
143 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
144 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
145 struct mptcp_options_received mp_opt;
146 bool opt_mp_capable, opt_mp_join;
147
148 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
149
150#ifdef CONFIG_TCP_MD5SIG
151 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
152 * TCP option space.
153 */
154 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
155 return -EINVAL;
156#endif
157
158 mptcp_get_options(skb, &mp_opt);
159
160 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN);
161 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN);
162 if (opt_mp_capable) {
163 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
164
165 if (opt_mp_join)
166 return 0;
167 } else if (opt_mp_join) {
168 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
169 }
170
171 if (opt_mp_capable && listener->request_mptcp) {
172 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
173
174 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
175again:
176 do {
177 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
178 } while (subflow_req->local_key == 0);
179
180 if (unlikely(req->syncookie)) {
181 mptcp_crypto_key_sha(subflow_req->local_key,
182 &subflow_req->token,
183 &subflow_req->idsn);
184 if (mptcp_token_exists(subflow_req->token)) {
185 if (retries-- > 0)
186 goto again;
187 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
188 } else {
189 subflow_req->mp_capable = 1;
190 }
191 return 0;
192 }
193
194 err = mptcp_token_new_request(req);
195 if (err == 0)
196 subflow_req->mp_capable = 1;
197 else if (retries-- > 0)
198 goto again;
199 else
200 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
201
202 } else if (opt_mp_join && listener->request_mptcp) {
203 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
204 subflow_req->mp_join = 1;
205 subflow_req->backup = mp_opt.backup;
206 subflow_req->remote_id = mp_opt.join_id;
207 subflow_req->token = mp_opt.token;
208 subflow_req->remote_nonce = mp_opt.nonce;
209 subflow_req->msk = subflow_token_join_request(req);
210
211 /* Can't fall back to TCP in this case. */
212 if (!subflow_req->msk) {
213 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
214 return -EPERM;
215 }
216
217 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
218 pr_debug("syn inet_sport=%d %d",
219 ntohs(inet_sk(sk_listener)->inet_sport),
220 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
221 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
222 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
223 return -EPERM;
224 }
225 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
226 }
227
228 subflow_req_create_thmac(subflow_req);
229
230 if (unlikely(req->syncookie)) {
231 if (mptcp_can_accept_new_subflow(subflow_req->msk))
232 subflow_init_req_cookie_join_save(subflow_req, skb);
233 else
234 return -EPERM;
235 }
236
237 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
238 subflow_req->remote_nonce, subflow_req->msk);
239 }
240
241 return 0;
242}
243
244int mptcp_subflow_init_cookie_req(struct request_sock *req,
245 const struct sock *sk_listener,
246 struct sk_buff *skb)
247{
248 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
249 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
250 struct mptcp_options_received mp_opt;
251 bool opt_mp_capable, opt_mp_join;
252 int err;
253
254 subflow_init_req(req, sk_listener);
255 mptcp_get_options(skb, &mp_opt);
256
257 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK);
258 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK);
259 if (opt_mp_capable && opt_mp_join)
260 return -EINVAL;
261
262 if (opt_mp_capable && listener->request_mptcp) {
263 if (mp_opt.sndr_key == 0)
264 return -EINVAL;
265
266 subflow_req->local_key = mp_opt.rcvr_key;
267 err = mptcp_token_new_request(req);
268 if (err)
269 return err;
270
271 subflow_req->mp_capable = 1;
272 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
273 } else if (opt_mp_join && listener->request_mptcp) {
274 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
275 return -EINVAL;
276
277 subflow_req->mp_join = 1;
278 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
279 }
280
281 return 0;
282}
283EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
284
285static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
286 struct sk_buff *skb,
287 struct flowi *fl,
288 struct request_sock *req)
289{
290 struct dst_entry *dst;
291 int err;
292
293 tcp_rsk(req)->is_mptcp = 1;
294 subflow_init_req(req, sk);
295
296 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
297 if (!dst)
298 return NULL;
299
300 err = subflow_check_req(req, sk, skb);
301 if (err == 0)
302 return dst;
303
304 dst_release(dst);
305 if (!req->syncookie)
306 tcp_request_sock_ops.send_reset(sk, skb);
307 return NULL;
308}
309
310static void subflow_prep_synack(const struct sock *sk, struct request_sock *req,
311 struct tcp_fastopen_cookie *foc,
312 enum tcp_synack_type synack_type)
313{
314 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
315 struct inet_request_sock *ireq = inet_rsk(req);
316
317 /* clear tstamp_ok, as needed depending on cookie */
318 if (foc && foc->len > -1)
319 ireq->tstamp_ok = 0;
320
321 if (synack_type == TCP_SYNACK_FASTOPEN)
322 mptcp_fastopen_subflow_synack_set_params(subflow, req);
323}
324
325static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
326 struct flowi *fl,
327 struct request_sock *req,
328 struct tcp_fastopen_cookie *foc,
329 enum tcp_synack_type synack_type,
330 struct sk_buff *syn_skb)
331{
332 subflow_prep_synack(sk, req, foc, synack_type);
333
334 return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc,
335 synack_type, syn_skb);
336}
337
338#if IS_ENABLED(CONFIG_MPTCP_IPV6)
339static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
340 struct flowi *fl,
341 struct request_sock *req,
342 struct tcp_fastopen_cookie *foc,
343 enum tcp_synack_type synack_type,
344 struct sk_buff *syn_skb)
345{
346 subflow_prep_synack(sk, req, foc, synack_type);
347
348 return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc,
349 synack_type, syn_skb);
350}
351
352static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
353 struct sk_buff *skb,
354 struct flowi *fl,
355 struct request_sock *req)
356{
357 struct dst_entry *dst;
358 int err;
359
360 tcp_rsk(req)->is_mptcp = 1;
361 subflow_init_req(req, sk);
362
363 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
364 if (!dst)
365 return NULL;
366
367 err = subflow_check_req(req, sk, skb);
368 if (err == 0)
369 return dst;
370
371 dst_release(dst);
372 if (!req->syncookie)
373 tcp6_request_sock_ops.send_reset(sk, skb);
374 return NULL;
375}
376#endif
377
378/* validate received truncated hmac and create hmac for third ACK */
379static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
380{
381 u8 hmac[SHA256_DIGEST_SIZE];
382 u64 thmac;
383
384 subflow_generate_hmac(subflow->remote_key, subflow->local_key,
385 subflow->remote_nonce, subflow->local_nonce,
386 hmac);
387
388 thmac = get_unaligned_be64(hmac);
389 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
390 subflow, subflow->token, thmac, subflow->thmac);
391
392 return thmac == subflow->thmac;
393}
394
395void mptcp_subflow_reset(struct sock *ssk)
396{
397 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
398 struct sock *sk = subflow->conn;
399
400 /* mptcp_mp_fail_no_response() can reach here on an already closed
401 * socket
402 */
403 if (ssk->sk_state == TCP_CLOSE)
404 return;
405
406 /* must hold: tcp_done() could drop last reference on parent */
407 sock_hold(sk);
408
409 tcp_send_active_reset(ssk, GFP_ATOMIC);
410 tcp_done(ssk);
411 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
412 mptcp_schedule_work(sk);
413
414 sock_put(sk);
415}
416
417static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
418{
419 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
420}
421
422void __mptcp_sync_state(struct sock *sk, int state)
423{
424 struct mptcp_subflow_context *subflow;
425 struct mptcp_sock *msk = mptcp_sk(sk);
426 struct sock *ssk = msk->first;
427
428 subflow = mptcp_subflow_ctx(ssk);
429 __mptcp_propagate_sndbuf(sk, ssk);
430 if (!msk->rcvspace_init)
431 mptcp_rcv_space_init(msk, ssk);
432
433 if (sk->sk_state == TCP_SYN_SENT) {
434 /* subflow->idsn is always available is TCP_SYN_SENT state,
435 * even for the FASTOPEN scenarios
436 */
437 WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
438 WRITE_ONCE(msk->snd_nxt, msk->write_seq);
439 mptcp_set_state(sk, state);
440 sk->sk_state_change(sk);
441 }
442}
443
444static void subflow_set_remote_key(struct mptcp_sock *msk,
445 struct mptcp_subflow_context *subflow,
446 const struct mptcp_options_received *mp_opt)
447{
448 /* active MPC subflow will reach here multiple times:
449 * at subflow_finish_connect() time and at 4th ack time
450 */
451 if (subflow->remote_key_valid)
452 return;
453
454 subflow->remote_key_valid = 1;
455 subflow->remote_key = mp_opt->sndr_key;
456 mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
457 subflow->iasn++;
458
459 WRITE_ONCE(msk->remote_key, subflow->remote_key);
460 WRITE_ONCE(msk->ack_seq, subflow->iasn);
461 WRITE_ONCE(msk->can_ack, true);
462 atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
463}
464
465static void mptcp_propagate_state(struct sock *sk, struct sock *ssk,
466 struct mptcp_subflow_context *subflow,
467 const struct mptcp_options_received *mp_opt)
468{
469 struct mptcp_sock *msk = mptcp_sk(sk);
470
471 mptcp_data_lock(sk);
472 if (mp_opt) {
473 /* Options are available only in the non fallback cases
474 * avoid updating rx path fields otherwise
475 */
476 WRITE_ONCE(msk->snd_una, subflow->idsn + 1);
477 WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd);
478 subflow_set_remote_key(msk, subflow, mp_opt);
479 }
480
481 if (!sock_owned_by_user(sk)) {
482 __mptcp_sync_state(sk, ssk->sk_state);
483 } else {
484 msk->pending_state = ssk->sk_state;
485 __set_bit(MPTCP_SYNC_STATE, &msk->cb_flags);
486 }
487 mptcp_data_unlock(sk);
488}
489
490static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
491{
492 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
493 struct mptcp_options_received mp_opt;
494 struct sock *parent = subflow->conn;
495 struct mptcp_sock *msk;
496
497 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
498
499 /* be sure no special action on any packet other than syn-ack */
500 if (subflow->conn_finished)
501 return;
502
503 msk = mptcp_sk(parent);
504 subflow->rel_write_seq = 1;
505 subflow->conn_finished = 1;
506 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
507 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
508
509 mptcp_get_options(skb, &mp_opt);
510 if (subflow->request_mptcp) {
511 if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) {
512 MPTCP_INC_STATS(sock_net(sk),
513 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
514 mptcp_do_fallback(sk);
515 pr_fallback(msk);
516 goto fallback;
517 }
518
519 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
520 WRITE_ONCE(msk->csum_enabled, true);
521 if (mp_opt.deny_join_id0)
522 WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
523 subflow->mp_capable = 1;
524 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
525 mptcp_finish_connect(sk);
526 mptcp_propagate_state(parent, sk, subflow, &mp_opt);
527 } else if (subflow->request_join) {
528 u8 hmac[SHA256_DIGEST_SIZE];
529
530 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) {
531 subflow->reset_reason = MPTCP_RST_EMPTCP;
532 goto do_reset;
533 }
534
535 subflow->backup = mp_opt.backup;
536 subflow->thmac = mp_opt.thmac;
537 subflow->remote_nonce = mp_opt.nonce;
538 WRITE_ONCE(subflow->remote_id, mp_opt.join_id);
539 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
540 subflow, subflow->thmac, subflow->remote_nonce,
541 subflow->backup);
542
543 if (!subflow_thmac_valid(subflow)) {
544 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
545 subflow->reset_reason = MPTCP_RST_EMPTCP;
546 goto do_reset;
547 }
548
549 if (!mptcp_finish_join(sk))
550 goto do_reset;
551
552 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
553 subflow->local_nonce,
554 subflow->remote_nonce,
555 hmac);
556 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
557
558 subflow->mp_join = 1;
559 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
560
561 if (subflow_use_different_dport(msk, sk)) {
562 pr_debug("synack inet_dport=%d %d",
563 ntohs(inet_sk(sk)->inet_dport),
564 ntohs(inet_sk(parent)->inet_dport));
565 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
566 }
567 } else if (mptcp_check_fallback(sk)) {
568fallback:
569 mptcp_propagate_state(parent, sk, subflow, NULL);
570 }
571 return;
572
573do_reset:
574 subflow->reset_transient = 0;
575 mptcp_subflow_reset(sk);
576}
577
578static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
579{
580 WARN_ON_ONCE(local_id < 0 || local_id > 255);
581 WRITE_ONCE(subflow->local_id, local_id);
582}
583
584static int subflow_chk_local_id(struct sock *sk)
585{
586 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
587 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
588 int err;
589
590 if (likely(subflow->local_id >= 0))
591 return 0;
592
593 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
594 if (err < 0)
595 return err;
596
597 subflow_set_local_id(subflow, err);
598 return 0;
599}
600
601static int subflow_rebuild_header(struct sock *sk)
602{
603 int err = subflow_chk_local_id(sk);
604
605 if (unlikely(err < 0))
606 return err;
607
608 return inet_sk_rebuild_header(sk);
609}
610
611#if IS_ENABLED(CONFIG_MPTCP_IPV6)
612static int subflow_v6_rebuild_header(struct sock *sk)
613{
614 int err = subflow_chk_local_id(sk);
615
616 if (unlikely(err < 0))
617 return err;
618
619 return inet6_sk_rebuild_header(sk);
620}
621#endif
622
623static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
624static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
625
626static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
627{
628 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
629
630 pr_debug("subflow=%p", subflow);
631
632 /* Never answer to SYNs sent to broadcast or multicast */
633 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
634 goto drop;
635
636 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
637 &subflow_request_sock_ipv4_ops,
638 sk, skb);
639drop:
640 tcp_listendrop(sk);
641 return 0;
642}
643
644static void subflow_v4_req_destructor(struct request_sock *req)
645{
646 subflow_req_destructor(req);
647 tcp_request_sock_ops.destructor(req);
648}
649
650#if IS_ENABLED(CONFIG_MPTCP_IPV6)
651static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
652static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
653static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
654static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
655static struct proto tcpv6_prot_override __ro_after_init;
656
657static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
658{
659 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
660
661 pr_debug("subflow=%p", subflow);
662
663 if (skb->protocol == htons(ETH_P_IP))
664 return subflow_v4_conn_request(sk, skb);
665
666 if (!ipv6_unicast_destination(skb))
667 goto drop;
668
669 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
670 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
671 return 0;
672 }
673
674 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
675 &subflow_request_sock_ipv6_ops, sk, skb);
676
677drop:
678 tcp_listendrop(sk);
679 return 0; /* don't send reset */
680}
681
682static void subflow_v6_req_destructor(struct request_sock *req)
683{
684 subflow_req_destructor(req);
685 tcp6_request_sock_ops.destructor(req);
686}
687#endif
688
689struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
690 struct sock *sk_listener,
691 bool attach_listener)
692{
693 if (ops->family == AF_INET)
694 ops = &mptcp_subflow_v4_request_sock_ops;
695#if IS_ENABLED(CONFIG_MPTCP_IPV6)
696 else if (ops->family == AF_INET6)
697 ops = &mptcp_subflow_v6_request_sock_ops;
698#endif
699
700 return inet_reqsk_alloc(ops, sk_listener, attach_listener);
701}
702EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
703
704/* validate hmac received in third ACK */
705static bool subflow_hmac_valid(const struct request_sock *req,
706 const struct mptcp_options_received *mp_opt)
707{
708 const struct mptcp_subflow_request_sock *subflow_req;
709 u8 hmac[SHA256_DIGEST_SIZE];
710 struct mptcp_sock *msk;
711
712 subflow_req = mptcp_subflow_rsk(req);
713 msk = subflow_req->msk;
714 if (!msk)
715 return false;
716
717 subflow_generate_hmac(msk->remote_key, msk->local_key,
718 subflow_req->remote_nonce,
719 subflow_req->local_nonce, hmac);
720
721 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
722}
723
724static void subflow_ulp_fallback(struct sock *sk,
725 struct mptcp_subflow_context *old_ctx)
726{
727 struct inet_connection_sock *icsk = inet_csk(sk);
728
729 mptcp_subflow_tcp_fallback(sk, old_ctx);
730 icsk->icsk_ulp_ops = NULL;
731 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
732 tcp_sk(sk)->is_mptcp = 0;
733
734 mptcp_subflow_ops_undo_override(sk);
735}
736
737void mptcp_subflow_drop_ctx(struct sock *ssk)
738{
739 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
740
741 if (!ctx)
742 return;
743
744 list_del(&mptcp_subflow_ctx(ssk)->node);
745 if (inet_csk(ssk)->icsk_ulp_ops) {
746 subflow_ulp_fallback(ssk, ctx);
747 if (ctx->conn)
748 sock_put(ctx->conn);
749 }
750
751 kfree_rcu(ctx, rcu);
752}
753
754void __mptcp_subflow_fully_established(struct mptcp_sock *msk,
755 struct mptcp_subflow_context *subflow,
756 const struct mptcp_options_received *mp_opt)
757{
758 subflow_set_remote_key(msk, subflow, mp_opt);
759 subflow->fully_established = 1;
760 WRITE_ONCE(msk->fully_established, true);
761
762 if (subflow->is_mptfo)
763 __mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt);
764}
765
766static struct sock *subflow_syn_recv_sock(const struct sock *sk,
767 struct sk_buff *skb,
768 struct request_sock *req,
769 struct dst_entry *dst,
770 struct request_sock *req_unhash,
771 bool *own_req)
772{
773 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
774 struct mptcp_subflow_request_sock *subflow_req;
775 struct mptcp_options_received mp_opt;
776 bool fallback, fallback_is_fatal;
777 struct mptcp_sock *owner;
778 struct sock *child;
779
780 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
781
782 /* After child creation we must look for MPC even when options
783 * are not parsed
784 */
785 mp_opt.suboptions = 0;
786
787 /* hopefully temporary handling for MP_JOIN+syncookie */
788 subflow_req = mptcp_subflow_rsk(req);
789 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
790 fallback = !tcp_rsk(req)->is_mptcp;
791 if (fallback)
792 goto create_child;
793
794 /* if the sk is MP_CAPABLE, we try to fetch the client key */
795 if (subflow_req->mp_capable) {
796 /* we can receive and accept an in-window, out-of-order pkt,
797 * which may not carry the MP_CAPABLE opt even on mptcp enabled
798 * paths: always try to extract the peer key, and fallback
799 * for packets missing it.
800 * Even OoO DSS packets coming legitly after dropped or
801 * reordered MPC will cause fallback, but we don't have other
802 * options.
803 */
804 mptcp_get_options(skb, &mp_opt);
805 if (!(mp_opt.suboptions &
806 (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK)))
807 fallback = true;
808
809 } else if (subflow_req->mp_join) {
810 mptcp_get_options(skb, &mp_opt);
811 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) ||
812 !subflow_hmac_valid(req, &mp_opt) ||
813 !mptcp_can_accept_new_subflow(subflow_req->msk)) {
814 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
815 fallback = true;
816 }
817 }
818
819create_child:
820 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
821 req_unhash, own_req);
822
823 if (child && *own_req) {
824 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
825
826 tcp_rsk(req)->drop_req = false;
827
828 /* we need to fallback on ctx allocation failure and on pre-reqs
829 * checking above. In the latter scenario we additionally need
830 * to reset the context to non MPTCP status.
831 */
832 if (!ctx || fallback) {
833 if (fallback_is_fatal) {
834 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
835 goto dispose_child;
836 }
837 goto fallback;
838 }
839
840 /* ssk inherits options of listener sk */
841 ctx->setsockopt_seq = listener->setsockopt_seq;
842
843 if (ctx->mp_capable) {
844 ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req);
845 if (!ctx->conn)
846 goto fallback;
847
848 ctx->subflow_id = 1;
849 owner = mptcp_sk(ctx->conn);
850 mptcp_pm_new_connection(owner, child, 1);
851
852 /* with OoO packets we can reach here without ingress
853 * mpc option
854 */
855 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) {
856 mptcp_pm_fully_established(owner, child);
857 ctx->pm_notified = 1;
858 }
859 } else if (ctx->mp_join) {
860 owner = subflow_req->msk;
861 if (!owner) {
862 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
863 goto dispose_child;
864 }
865
866 /* move the msk reference ownership to the subflow */
867 subflow_req->msk = NULL;
868 ctx->conn = (struct sock *)owner;
869
870 if (subflow_use_different_sport(owner, sk)) {
871 pr_debug("ack inet_sport=%d %d",
872 ntohs(inet_sk(sk)->inet_sport),
873 ntohs(inet_sk((struct sock *)owner)->inet_sport));
874 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
875 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
876 goto dispose_child;
877 }
878 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
879 }
880
881 if (!mptcp_finish_join(child))
882 goto dispose_child;
883
884 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
885 tcp_rsk(req)->drop_req = true;
886 }
887 }
888
889 /* check for expected invariant - should never trigger, just help
890 * catching eariler subtle bugs
891 */
892 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
893 (!mptcp_subflow_ctx(child) ||
894 !mptcp_subflow_ctx(child)->conn));
895 return child;
896
897dispose_child:
898 mptcp_subflow_drop_ctx(child);
899 tcp_rsk(req)->drop_req = true;
900 inet_csk_prepare_for_destroy_sock(child);
901 tcp_done(child);
902 req->rsk_ops->send_reset(sk, skb);
903
904 /* The last child reference will be released by the caller */
905 return child;
906
907fallback:
908 mptcp_subflow_drop_ctx(child);
909 return child;
910}
911
912static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
913static struct proto tcp_prot_override __ro_after_init;
914
915enum mapping_status {
916 MAPPING_OK,
917 MAPPING_INVALID,
918 MAPPING_EMPTY,
919 MAPPING_DATA_FIN,
920 MAPPING_DUMMY,
921 MAPPING_BAD_CSUM
922};
923
924static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
925{
926 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
927 ssn, subflow->map_subflow_seq, subflow->map_data_len);
928}
929
930static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
931{
932 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
933 unsigned int skb_consumed;
934
935 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
936 if (WARN_ON_ONCE(skb_consumed >= skb->len))
937 return true;
938
939 return skb->len - skb_consumed <= subflow->map_data_len -
940 mptcp_subflow_get_map_offset(subflow);
941}
942
943static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
944{
945 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
946 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
947
948 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
949 /* Mapping covers data later in the subflow stream,
950 * currently unsupported.
951 */
952 dbg_bad_map(subflow, ssn);
953 return false;
954 }
955 if (unlikely(!before(ssn, subflow->map_subflow_seq +
956 subflow->map_data_len))) {
957 /* Mapping does covers past subflow data, invalid */
958 dbg_bad_map(subflow, ssn);
959 return false;
960 }
961 return true;
962}
963
964static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
965 bool csum_reqd)
966{
967 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
968 u32 offset, seq, delta;
969 __sum16 csum;
970 int len;
971
972 if (!csum_reqd)
973 return MAPPING_OK;
974
975 /* mapping already validated on previous traversal */
976 if (subflow->map_csum_len == subflow->map_data_len)
977 return MAPPING_OK;
978
979 /* traverse the receive queue, ensuring it contains a full
980 * DSS mapping and accumulating the related csum.
981 * Preserve the accoumlate csum across multiple calls, to compute
982 * the csum only once
983 */
984 delta = subflow->map_data_len - subflow->map_csum_len;
985 for (;;) {
986 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
987 offset = seq - TCP_SKB_CB(skb)->seq;
988
989 /* if the current skb has not been accounted yet, csum its contents
990 * up to the amount covered by the current DSS
991 */
992 if (offset < skb->len) {
993 __wsum csum;
994
995 len = min(skb->len - offset, delta);
996 csum = skb_checksum(skb, offset, len, 0);
997 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
998 subflow->map_csum_len);
999
1000 delta -= len;
1001 subflow->map_csum_len += len;
1002 }
1003 if (delta == 0)
1004 break;
1005
1006 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
1007 /* if this subflow is closed, the partial mapping
1008 * will be never completed; flush the pending skbs, so
1009 * that subflow_sched_work_if_closed() can kick in
1010 */
1011 if (unlikely(ssk->sk_state == TCP_CLOSE))
1012 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1013 sk_eat_skb(ssk, skb);
1014
1015 /* not enough data to validate the csum */
1016 return MAPPING_EMPTY;
1017 }
1018
1019 /* the DSS mapping for next skbs will be validated later,
1020 * when a get_mapping_status call will process such skb
1021 */
1022 skb = skb->next;
1023 }
1024
1025 /* note that 'map_data_len' accounts only for the carried data, does
1026 * not include the eventual seq increment due to the data fin,
1027 * while the pseudo header requires the original DSS data len,
1028 * including that
1029 */
1030 csum = __mptcp_make_csum(subflow->map_seq,
1031 subflow->map_subflow_seq,
1032 subflow->map_data_len + subflow->map_data_fin,
1033 subflow->map_data_csum);
1034 if (unlikely(csum)) {
1035 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
1036 return MAPPING_BAD_CSUM;
1037 }
1038
1039 subflow->valid_csum_seen = 1;
1040 return MAPPING_OK;
1041}
1042
1043static enum mapping_status get_mapping_status(struct sock *ssk,
1044 struct mptcp_sock *msk)
1045{
1046 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1047 bool csum_reqd = READ_ONCE(msk->csum_enabled);
1048 struct mptcp_ext *mpext;
1049 struct sk_buff *skb;
1050 u16 data_len;
1051 u64 map_seq;
1052
1053 skb = skb_peek(&ssk->sk_receive_queue);
1054 if (!skb)
1055 return MAPPING_EMPTY;
1056
1057 if (mptcp_check_fallback(ssk))
1058 return MAPPING_DUMMY;
1059
1060 mpext = mptcp_get_ext(skb);
1061 if (!mpext || !mpext->use_map) {
1062 if (!subflow->map_valid && !skb->len) {
1063 /* the TCP stack deliver 0 len FIN pkt to the receive
1064 * queue, that is the only 0len pkts ever expected here,
1065 * and we can admit no mapping only for 0 len pkts
1066 */
1067 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
1068 WARN_ONCE(1, "0len seq %d:%d flags %x",
1069 TCP_SKB_CB(skb)->seq,
1070 TCP_SKB_CB(skb)->end_seq,
1071 TCP_SKB_CB(skb)->tcp_flags);
1072 sk_eat_skb(ssk, skb);
1073 return MAPPING_EMPTY;
1074 }
1075
1076 if (!subflow->map_valid)
1077 return MAPPING_INVALID;
1078
1079 goto validate_seq;
1080 }
1081
1082 trace_get_mapping_status(mpext);
1083
1084 data_len = mpext->data_len;
1085 if (data_len == 0) {
1086 pr_debug("infinite mapping received");
1087 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
1088 subflow->map_data_len = 0;
1089 return MAPPING_INVALID;
1090 }
1091
1092 if (mpext->data_fin == 1) {
1093 if (data_len == 1) {
1094 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
1095 mpext->dsn64);
1096 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
1097 if (subflow->map_valid) {
1098 /* A DATA_FIN might arrive in a DSS
1099 * option before the previous mapping
1100 * has been fully consumed. Continue
1101 * handling the existing mapping.
1102 */
1103 skb_ext_del(skb, SKB_EXT_MPTCP);
1104 return MAPPING_OK;
1105 } else {
1106 if (updated)
1107 mptcp_schedule_work((struct sock *)msk);
1108
1109 return MAPPING_DATA_FIN;
1110 }
1111 } else {
1112 u64 data_fin_seq = mpext->data_seq + data_len - 1;
1113
1114 /* If mpext->data_seq is a 32-bit value, data_fin_seq
1115 * must also be limited to 32 bits.
1116 */
1117 if (!mpext->dsn64)
1118 data_fin_seq &= GENMASK_ULL(31, 0);
1119
1120 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1121 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
1122 data_fin_seq, mpext->dsn64);
1123 }
1124
1125 /* Adjust for DATA_FIN using 1 byte of sequence space */
1126 data_len--;
1127 }
1128
1129 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1130 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1131
1132 if (subflow->map_valid) {
1133 /* Allow replacing only with an identical map */
1134 if (subflow->map_seq == map_seq &&
1135 subflow->map_subflow_seq == mpext->subflow_seq &&
1136 subflow->map_data_len == data_len &&
1137 subflow->map_csum_reqd == mpext->csum_reqd) {
1138 skb_ext_del(skb, SKB_EXT_MPTCP);
1139 goto validate_csum;
1140 }
1141
1142 /* If this skb data are fully covered by the current mapping,
1143 * the new map would need caching, which is not supported
1144 */
1145 if (skb_is_fully_mapped(ssk, skb)) {
1146 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1147 return MAPPING_INVALID;
1148 }
1149
1150 /* will validate the next map after consuming the current one */
1151 goto validate_csum;
1152 }
1153
1154 subflow->map_seq = map_seq;
1155 subflow->map_subflow_seq = mpext->subflow_seq;
1156 subflow->map_data_len = data_len;
1157 subflow->map_valid = 1;
1158 subflow->map_data_fin = mpext->data_fin;
1159 subflow->mpc_map = mpext->mpc_map;
1160 subflow->map_csum_reqd = mpext->csum_reqd;
1161 subflow->map_csum_len = 0;
1162 subflow->map_data_csum = csum_unfold(mpext->csum);
1163
1164 /* Cfr RFC 8684 Section 3.3.0 */
1165 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1166 return MAPPING_INVALID;
1167
1168 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1169 subflow->map_seq, subflow->map_subflow_seq,
1170 subflow->map_data_len, subflow->map_csum_reqd,
1171 subflow->map_data_csum);
1172
1173validate_seq:
1174 /* we revalidate valid mapping on new skb, because we must ensure
1175 * the current skb is completely covered by the available mapping
1176 */
1177 if (!validate_mapping(ssk, skb)) {
1178 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1179 return MAPPING_INVALID;
1180 }
1181
1182 skb_ext_del(skb, SKB_EXT_MPTCP);
1183
1184validate_csum:
1185 return validate_data_csum(ssk, skb, csum_reqd);
1186}
1187
1188static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1189 u64 limit)
1190{
1191 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1192 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1193 u32 incr;
1194
1195 incr = limit >= skb->len ? skb->len + fin : limit;
1196
1197 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1198 subflow->map_subflow_seq);
1199 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1200 tcp_sk(ssk)->copied_seq += incr;
1201 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1202 sk_eat_skb(ssk, skb);
1203 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1204 subflow->map_valid = 0;
1205}
1206
1207/* sched mptcp worker to remove the subflow if no more data is pending */
1208static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1209{
1210 if (likely(ssk->sk_state != TCP_CLOSE))
1211 return;
1212
1213 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1214 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
1215 mptcp_schedule_work((struct sock *)msk);
1216}
1217
1218static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
1219{
1220 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1221
1222 if (subflow->mp_join)
1223 return false;
1224 else if (READ_ONCE(msk->csum_enabled))
1225 return !subflow->valid_csum_seen;
1226 else
1227 return !subflow->fully_established;
1228}
1229
1230static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1231{
1232 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1233 unsigned long fail_tout;
1234
1235 /* greceful failure can happen only on the MPC subflow */
1236 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1237 return;
1238
1239 /* since the close timeout take precedence on the fail one,
1240 * no need to start the latter when the first is already set
1241 */
1242 if (sock_flag((struct sock *)msk, SOCK_DEAD))
1243 return;
1244
1245 /* we don't need extreme accuracy here, use a zero fail_tout as special
1246 * value meaning no fail timeout at all;
1247 */
1248 fail_tout = jiffies + TCP_RTO_MAX;
1249 if (!fail_tout)
1250 fail_tout = 1;
1251 WRITE_ONCE(subflow->fail_tout, fail_tout);
1252 tcp_send_ack(ssk);
1253
1254 mptcp_reset_tout_timer(msk, subflow->fail_tout);
1255}
1256
1257static bool subflow_check_data_avail(struct sock *ssk)
1258{
1259 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1260 enum mapping_status status;
1261 struct mptcp_sock *msk;
1262 struct sk_buff *skb;
1263
1264 if (!skb_peek(&ssk->sk_receive_queue))
1265 WRITE_ONCE(subflow->data_avail, false);
1266 if (subflow->data_avail)
1267 return true;
1268
1269 msk = mptcp_sk(subflow->conn);
1270 for (;;) {
1271 u64 ack_seq;
1272 u64 old_ack;
1273
1274 status = get_mapping_status(ssk, msk);
1275 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1276 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1277 status == MAPPING_BAD_CSUM))
1278 goto fallback;
1279
1280 if (status != MAPPING_OK)
1281 goto no_data;
1282
1283 skb = skb_peek(&ssk->sk_receive_queue);
1284 if (WARN_ON_ONCE(!skb))
1285 goto no_data;
1286
1287 if (unlikely(!READ_ONCE(msk->can_ack)))
1288 goto fallback;
1289
1290 old_ack = READ_ONCE(msk->ack_seq);
1291 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1292 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1293 ack_seq);
1294 if (unlikely(before64(ack_seq, old_ack))) {
1295 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1296 continue;
1297 }
1298
1299 WRITE_ONCE(subflow->data_avail, true);
1300 break;
1301 }
1302 return true;
1303
1304no_data:
1305 subflow_sched_work_if_closed(msk, ssk);
1306 return false;
1307
1308fallback:
1309 if (!__mptcp_check_fallback(msk)) {
1310 /* RFC 8684 section 3.7. */
1311 if (status == MAPPING_BAD_CSUM &&
1312 (subflow->mp_join || subflow->valid_csum_seen)) {
1313 subflow->send_mp_fail = 1;
1314
1315 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1316 subflow->reset_transient = 0;
1317 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1318 goto reset;
1319 }
1320 mptcp_subflow_fail(msk, ssk);
1321 WRITE_ONCE(subflow->data_avail, true);
1322 return true;
1323 }
1324
1325 if (!subflow_can_fallback(subflow) && subflow->map_data_len) {
1326 /* fatal protocol error, close the socket.
1327 * subflow_error_report() will introduce the appropriate barriers
1328 */
1329 subflow->reset_transient = 0;
1330 subflow->reset_reason = MPTCP_RST_EMPTCP;
1331
1332reset:
1333 WRITE_ONCE(ssk->sk_err, EBADMSG);
1334 tcp_set_state(ssk, TCP_CLOSE);
1335 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1336 sk_eat_skb(ssk, skb);
1337 tcp_send_active_reset(ssk, GFP_ATOMIC);
1338 WRITE_ONCE(subflow->data_avail, false);
1339 return false;
1340 }
1341
1342 mptcp_do_fallback(ssk);
1343 }
1344
1345 skb = skb_peek(&ssk->sk_receive_queue);
1346 subflow->map_valid = 1;
1347 subflow->map_seq = READ_ONCE(msk->ack_seq);
1348 subflow->map_data_len = skb->len;
1349 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1350 WRITE_ONCE(subflow->data_avail, true);
1351 return true;
1352}
1353
1354bool mptcp_subflow_data_available(struct sock *sk)
1355{
1356 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1357
1358 /* check if current mapping is still valid */
1359 if (subflow->map_valid &&
1360 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1361 subflow->map_valid = 0;
1362 WRITE_ONCE(subflow->data_avail, false);
1363
1364 pr_debug("Done with mapping: seq=%u data_len=%u",
1365 subflow->map_subflow_seq,
1366 subflow->map_data_len);
1367 }
1368
1369 return subflow_check_data_avail(sk);
1370}
1371
1372/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1373 * not the ssk one.
1374 *
1375 * In mptcp, rwin is about the mptcp-level connection data.
1376 *
1377 * Data that is still on the ssk rx queue can thus be ignored,
1378 * as far as mptcp peer is concerned that data is still inflight.
1379 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1380 */
1381void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1382{
1383 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1384 const struct sock *sk = subflow->conn;
1385
1386 *space = __mptcp_space(sk);
1387 *full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1388}
1389
1390static void subflow_error_report(struct sock *ssk)
1391{
1392 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1393
1394 /* bail early if this is a no-op, so that we avoid introducing a
1395 * problematic lockdep dependency between TCP accept queue lock
1396 * and msk socket spinlock
1397 */
1398 if (!sk->sk_socket)
1399 return;
1400
1401 mptcp_data_lock(sk);
1402 if (!sock_owned_by_user(sk))
1403 __mptcp_error_report(sk);
1404 else
1405 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
1406 mptcp_data_unlock(sk);
1407}
1408
1409static void subflow_data_ready(struct sock *sk)
1410{
1411 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1412 u16 state = 1 << inet_sk_state_load(sk);
1413 struct sock *parent = subflow->conn;
1414 struct mptcp_sock *msk;
1415
1416 trace_sk_data_ready(sk);
1417
1418 msk = mptcp_sk(parent);
1419 if (state & TCPF_LISTEN) {
1420 /* MPJ subflow are removed from accept queue before reaching here,
1421 * avoid stray wakeups
1422 */
1423 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1424 return;
1425
1426 parent->sk_data_ready(parent);
1427 return;
1428 }
1429
1430 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1431 !subflow->mp_join && !(state & TCPF_CLOSE));
1432
1433 if (mptcp_subflow_data_available(sk)) {
1434 mptcp_data_ready(parent, sk);
1435
1436 /* subflow-level lowat test are not relevant.
1437 * respect the msk-level threshold eventually mandating an immediate ack
1438 */
1439 if (mptcp_data_avail(msk) < parent->sk_rcvlowat &&
1440 (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss)
1441 inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
1442 } else if (unlikely(sk->sk_err)) {
1443 subflow_error_report(sk);
1444 }
1445}
1446
1447static void subflow_write_space(struct sock *ssk)
1448{
1449 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1450
1451 mptcp_propagate_sndbuf(sk, ssk);
1452 mptcp_write_space(sk);
1453}
1454
1455static const struct inet_connection_sock_af_ops *
1456subflow_default_af_ops(struct sock *sk)
1457{
1458#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1459 if (sk->sk_family == AF_INET6)
1460 return &subflow_v6_specific;
1461#endif
1462 return &subflow_specific;
1463}
1464
1465#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1466void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1467{
1468 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1469 struct inet_connection_sock *icsk = inet_csk(sk);
1470 const struct inet_connection_sock_af_ops *target;
1471
1472 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1473
1474 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1475 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1476
1477 if (likely(icsk->icsk_af_ops == target))
1478 return;
1479
1480 subflow->icsk_af_ops = icsk->icsk_af_ops;
1481 icsk->icsk_af_ops = target;
1482}
1483#endif
1484
1485void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1486 struct sockaddr_storage *addr,
1487 unsigned short family)
1488{
1489 memset(addr, 0, sizeof(*addr));
1490 addr->ss_family = family;
1491 if (addr->ss_family == AF_INET) {
1492 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1493
1494 if (info->family == AF_INET)
1495 in_addr->sin_addr = info->addr;
1496#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1497 else if (ipv6_addr_v4mapped(&info->addr6))
1498 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1499#endif
1500 in_addr->sin_port = info->port;
1501 }
1502#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1503 else if (addr->ss_family == AF_INET6) {
1504 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1505
1506 if (info->family == AF_INET)
1507 ipv6_addr_set_v4mapped(info->addr.s_addr,
1508 &in6_addr->sin6_addr);
1509 else
1510 in6_addr->sin6_addr = info->addr6;
1511 in6_addr->sin6_port = info->port;
1512 }
1513#endif
1514}
1515
1516int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1517 const struct mptcp_addr_info *remote)
1518{
1519 struct mptcp_sock *msk = mptcp_sk(sk);
1520 struct mptcp_subflow_context *subflow;
1521 struct sockaddr_storage addr;
1522 int remote_id = remote->id;
1523 int local_id = loc->id;
1524 int err = -ENOTCONN;
1525 struct socket *sf;
1526 struct sock *ssk;
1527 u32 remote_token;
1528 int addrlen;
1529 int ifindex;
1530 u8 flags;
1531
1532 if (!mptcp_is_fully_established(sk))
1533 goto err_out;
1534
1535 err = mptcp_subflow_create_socket(sk, loc->family, &sf);
1536 if (err)
1537 goto err_out;
1538
1539 ssk = sf->sk;
1540 subflow = mptcp_subflow_ctx(ssk);
1541 do {
1542 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1543 } while (!subflow->local_nonce);
1544
1545 if (local_id)
1546 subflow_set_local_id(subflow, local_id);
1547
1548 mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id,
1549 &flags, &ifindex);
1550 subflow->remote_key_valid = 1;
1551 subflow->remote_key = msk->remote_key;
1552 subflow->local_key = msk->local_key;
1553 subflow->token = msk->token;
1554 mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1555
1556 addrlen = sizeof(struct sockaddr_in);
1557#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1558 if (addr.ss_family == AF_INET6)
1559 addrlen = sizeof(struct sockaddr_in6);
1560#endif
1561 ssk->sk_bound_dev_if = ifindex;
1562 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1563 if (err)
1564 goto failed;
1565
1566 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1567 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1568 remote_token, local_id, remote_id);
1569 subflow->remote_token = remote_token;
1570 WRITE_ONCE(subflow->remote_id, remote_id);
1571 subflow->request_join = 1;
1572 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1573 subflow->subflow_id = msk->subflow_id++;
1574 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1575
1576 sock_hold(ssk);
1577 list_add_tail(&subflow->node, &msk->conn_list);
1578 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1579 if (err && err != -EINPROGRESS)
1580 goto failed_unlink;
1581
1582 /* discard the subflow socket */
1583 mptcp_sock_graft(ssk, sk->sk_socket);
1584 iput(SOCK_INODE(sf));
1585 WRITE_ONCE(msk->allow_infinite_fallback, false);
1586 mptcp_stop_tout_timer(sk);
1587 return 0;
1588
1589failed_unlink:
1590 list_del(&subflow->node);
1591 sock_put(mptcp_subflow_tcp_sock(subflow));
1592
1593failed:
1594 subflow->disposable = 1;
1595 sock_release(sf);
1596
1597err_out:
1598 /* we account subflows before the creation, and this failures will not
1599 * be caught by sk_state_change()
1600 */
1601 mptcp_pm_close_subflow(msk);
1602 return err;
1603}
1604
1605static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1606{
1607#ifdef CONFIG_SOCK_CGROUP_DATA
1608 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1609 *child_skcd = &child->sk_cgrp_data;
1610
1611 /* only the additional subflows created by kworkers have to be modified */
1612 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1613 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1614#ifdef CONFIG_MEMCG
1615 struct mem_cgroup *memcg = parent->sk_memcg;
1616
1617 mem_cgroup_sk_free(child);
1618 if (memcg && css_tryget(&memcg->css))
1619 child->sk_memcg = memcg;
1620#endif /* CONFIG_MEMCG */
1621
1622 cgroup_sk_free(child_skcd);
1623 *child_skcd = *parent_skcd;
1624 cgroup_sk_clone(child_skcd);
1625 }
1626#endif /* CONFIG_SOCK_CGROUP_DATA */
1627}
1628
1629static void mptcp_subflow_ops_override(struct sock *ssk)
1630{
1631#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1632 if (ssk->sk_prot == &tcpv6_prot)
1633 ssk->sk_prot = &tcpv6_prot_override;
1634 else
1635#endif
1636 ssk->sk_prot = &tcp_prot_override;
1637}
1638
1639static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1640{
1641#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1642 if (ssk->sk_prot == &tcpv6_prot_override)
1643 ssk->sk_prot = &tcpv6_prot;
1644 else
1645#endif
1646 ssk->sk_prot = &tcp_prot;
1647}
1648
1649int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1650 struct socket **new_sock)
1651{
1652 struct mptcp_subflow_context *subflow;
1653 struct net *net = sock_net(sk);
1654 struct socket *sf;
1655 int err;
1656
1657 /* un-accepted server sockets can reach here - on bad configuration
1658 * bail early to avoid greater trouble later
1659 */
1660 if (unlikely(!sk->sk_socket))
1661 return -EINVAL;
1662
1663 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
1664 if (err)
1665 return err;
1666
1667 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
1668
1669 err = security_mptcp_add_subflow(sk, sf->sk);
1670 if (err)
1671 goto err_free;
1672
1673 /* the newly created socket has to be in the same cgroup as its parent */
1674 mptcp_attach_cgroup(sk, sf->sk);
1675
1676 /* kernel sockets do not by default acquire net ref, but TCP timer
1677 * needs it.
1678 * Update ns_tracker to current stack trace and refcounted tracker.
1679 */
1680 __netns_tracker_free(net, &sf->sk->ns_tracker, false);
1681 sf->sk->sk_net_refcnt = 1;
1682 get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL);
1683 sock_inuse_add(net, 1);
1684 err = tcp_set_ulp(sf->sk, "mptcp");
1685 if (err)
1686 goto err_free;
1687
1688 mptcp_sockopt_sync_locked(mptcp_sk(sk), sf->sk);
1689 release_sock(sf->sk);
1690
1691 /* the newly created socket really belongs to the owning MPTCP master
1692 * socket, even if for additional subflows the allocation is performed
1693 * by a kernel workqueue. Adjust inode references, so that the
1694 * procfs/diag interfaces really show this one belonging to the correct
1695 * user.
1696 */
1697 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1698 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1699 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1700
1701 subflow = mptcp_subflow_ctx(sf->sk);
1702 pr_debug("subflow=%p", subflow);
1703
1704 *new_sock = sf;
1705 sock_hold(sk);
1706 subflow->conn = sk;
1707 mptcp_subflow_ops_override(sf->sk);
1708
1709 return 0;
1710
1711err_free:
1712 release_sock(sf->sk);
1713 sock_release(sf);
1714 return err;
1715}
1716
1717static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1718 gfp_t priority)
1719{
1720 struct inet_connection_sock *icsk = inet_csk(sk);
1721 struct mptcp_subflow_context *ctx;
1722
1723 ctx = kzalloc(sizeof(*ctx), priority);
1724 if (!ctx)
1725 return NULL;
1726
1727 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1728 INIT_LIST_HEAD(&ctx->node);
1729 INIT_LIST_HEAD(&ctx->delegated_node);
1730
1731 pr_debug("subflow=%p", ctx);
1732
1733 ctx->tcp_sock = sk;
1734 WRITE_ONCE(ctx->local_id, -1);
1735
1736 return ctx;
1737}
1738
1739static void __subflow_state_change(struct sock *sk)
1740{
1741 struct socket_wq *wq;
1742
1743 rcu_read_lock();
1744 wq = rcu_dereference(sk->sk_wq);
1745 if (skwq_has_sleeper(wq))
1746 wake_up_interruptible_all(&wq->wait);
1747 rcu_read_unlock();
1748}
1749
1750static bool subflow_is_done(const struct sock *sk)
1751{
1752 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1753}
1754
1755static void subflow_state_change(struct sock *sk)
1756{
1757 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1758 struct sock *parent = subflow->conn;
1759 struct mptcp_sock *msk;
1760
1761 __subflow_state_change(sk);
1762
1763 msk = mptcp_sk(parent);
1764 if (subflow_simultaneous_connect(sk)) {
1765 mptcp_do_fallback(sk);
1766 pr_fallback(msk);
1767 subflow->conn_finished = 1;
1768 mptcp_propagate_state(parent, sk, subflow, NULL);
1769 }
1770
1771 /* as recvmsg() does not acquire the subflow socket for ssk selection
1772 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1773 * the data available machinery here.
1774 */
1775 if (mptcp_subflow_data_available(sk))
1776 mptcp_data_ready(parent, sk);
1777 else if (unlikely(sk->sk_err))
1778 subflow_error_report(sk);
1779
1780 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1781
1782 /* when the fallback subflow closes the rx side, trigger a 'dummy'
1783 * ingress data fin, so that the msk state will follow along
1784 */
1785 if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
1786 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
1787 mptcp_schedule_work(parent);
1788}
1789
1790void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1791{
1792 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
1793 struct request_sock *req, *head, *tail;
1794 struct mptcp_subflow_context *subflow;
1795 struct sock *sk, *ssk;
1796
1797 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
1798 * Splice the req list, so that accept() can not reach the pending ssk after
1799 * the listener socket is released below.
1800 */
1801 spin_lock_bh(&queue->rskq_lock);
1802 head = queue->rskq_accept_head;
1803 tail = queue->rskq_accept_tail;
1804 queue->rskq_accept_head = NULL;
1805 queue->rskq_accept_tail = NULL;
1806 spin_unlock_bh(&queue->rskq_lock);
1807
1808 if (!head)
1809 return;
1810
1811 /* can't acquire the msk socket lock under the subflow one,
1812 * or will cause ABBA deadlock
1813 */
1814 release_sock(listener_ssk);
1815
1816 for (req = head; req; req = req->dl_next) {
1817 ssk = req->sk;
1818 if (!sk_is_mptcp(ssk))
1819 continue;
1820
1821 subflow = mptcp_subflow_ctx(ssk);
1822 if (!subflow || !subflow->conn)
1823 continue;
1824
1825 sk = subflow->conn;
1826 sock_hold(sk);
1827
1828 lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1829 __mptcp_unaccepted_force_close(sk);
1830 release_sock(sk);
1831
1832 /* lockdep will report a false positive ABBA deadlock
1833 * between cancel_work_sync and the listener socket.
1834 * The involved locks belong to different sockets WRT
1835 * the existing AB chain.
1836 * Using a per socket key is problematic as key
1837 * deregistration requires process context and must be
1838 * performed at socket disposal time, in atomic
1839 * context.
1840 * Just tell lockdep to consider the listener socket
1841 * released here.
1842 */
1843 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1844 mptcp_cancel_work(sk);
1845 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
1846
1847 sock_put(sk);
1848 }
1849
1850 /* we are still under the listener msk socket lock */
1851 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
1852
1853 /* restore the listener queue, to let the TCP code clean it up */
1854 spin_lock_bh(&queue->rskq_lock);
1855 WARN_ON_ONCE(queue->rskq_accept_head);
1856 queue->rskq_accept_head = head;
1857 queue->rskq_accept_tail = tail;
1858 spin_unlock_bh(&queue->rskq_lock);
1859}
1860
1861static int subflow_ulp_init(struct sock *sk)
1862{
1863 struct inet_connection_sock *icsk = inet_csk(sk);
1864 struct mptcp_subflow_context *ctx;
1865 struct tcp_sock *tp = tcp_sk(sk);
1866 int err = 0;
1867
1868 /* disallow attaching ULP to a socket unless it has been
1869 * created with sock_create_kern()
1870 */
1871 if (!sk->sk_kern_sock) {
1872 err = -EOPNOTSUPP;
1873 goto out;
1874 }
1875
1876 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1877 if (!ctx) {
1878 err = -ENOMEM;
1879 goto out;
1880 }
1881
1882 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1883
1884 tp->is_mptcp = 1;
1885 ctx->icsk_af_ops = icsk->icsk_af_ops;
1886 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1887 ctx->tcp_state_change = sk->sk_state_change;
1888 ctx->tcp_error_report = sk->sk_error_report;
1889
1890 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1891 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1892
1893 sk->sk_data_ready = subflow_data_ready;
1894 sk->sk_write_space = subflow_write_space;
1895 sk->sk_state_change = subflow_state_change;
1896 sk->sk_error_report = subflow_error_report;
1897out:
1898 return err;
1899}
1900
1901static void subflow_ulp_release(struct sock *ssk)
1902{
1903 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1904 bool release = true;
1905 struct sock *sk;
1906
1907 if (!ctx)
1908 return;
1909
1910 sk = ctx->conn;
1911 if (sk) {
1912 /* if the msk has been orphaned, keep the ctx
1913 * alive, will be freed by __mptcp_close_ssk(),
1914 * when the subflow is still unaccepted
1915 */
1916 release = ctx->disposable || list_empty(&ctx->node);
1917
1918 /* inet_child_forget() does not call sk_state_change(),
1919 * explicitly trigger the socket close machinery
1920 */
1921 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
1922 &mptcp_sk(sk)->flags))
1923 mptcp_schedule_work(sk);
1924 sock_put(sk);
1925 }
1926
1927 mptcp_subflow_ops_undo_override(ssk);
1928 if (release)
1929 kfree_rcu(ctx, rcu);
1930}
1931
1932static void subflow_ulp_clone(const struct request_sock *req,
1933 struct sock *newsk,
1934 const gfp_t priority)
1935{
1936 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1937 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1938 struct mptcp_subflow_context *new_ctx;
1939
1940 if (!tcp_rsk(req)->is_mptcp ||
1941 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1942 subflow_ulp_fallback(newsk, old_ctx);
1943 return;
1944 }
1945
1946 new_ctx = subflow_create_ctx(newsk, priority);
1947 if (!new_ctx) {
1948 subflow_ulp_fallback(newsk, old_ctx);
1949 return;
1950 }
1951
1952 new_ctx->conn_finished = 1;
1953 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1954 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1955 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1956 new_ctx->rel_write_seq = 1;
1957 new_ctx->tcp_sock = newsk;
1958
1959 if (subflow_req->mp_capable) {
1960 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1961 * is fully established only after we receive the remote key
1962 */
1963 new_ctx->mp_capable = 1;
1964 new_ctx->local_key = subflow_req->local_key;
1965 new_ctx->token = subflow_req->token;
1966 new_ctx->ssn_offset = subflow_req->ssn_offset;
1967 new_ctx->idsn = subflow_req->idsn;
1968
1969 /* this is the first subflow, id is always 0 */
1970 subflow_set_local_id(new_ctx, 0);
1971 } else if (subflow_req->mp_join) {
1972 new_ctx->ssn_offset = subflow_req->ssn_offset;
1973 new_ctx->mp_join = 1;
1974 new_ctx->fully_established = 1;
1975 new_ctx->remote_key_valid = 1;
1976 new_ctx->backup = subflow_req->backup;
1977 WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id);
1978 new_ctx->token = subflow_req->token;
1979 new_ctx->thmac = subflow_req->thmac;
1980
1981 /* the subflow req id is valid, fetched via subflow_check_req()
1982 * and subflow_token_join_request()
1983 */
1984 subflow_set_local_id(new_ctx, subflow_req->local_id);
1985 }
1986}
1987
1988static void tcp_release_cb_override(struct sock *ssk)
1989{
1990 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1991 long status;
1992
1993 /* process and clear all the pending actions, but leave the subflow into
1994 * the napi queue. To respect locking, only the same CPU that originated
1995 * the action can touch the list. mptcp_napi_poll will take care of it.
1996 */
1997 status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0);
1998 if (status)
1999 mptcp_subflow_process_delegated(ssk, status);
2000
2001 tcp_release_cb(ssk);
2002}
2003
2004static int tcp_abort_override(struct sock *ssk, int err)
2005{
2006 /* closing a listener subflow requires a great deal of care.
2007 * keep it simple and just prevent such operation
2008 */
2009 if (inet_sk_state_load(ssk) == TCP_LISTEN)
2010 return -EINVAL;
2011
2012 return tcp_abort(ssk, err);
2013}
2014
2015static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
2016 .name = "mptcp",
2017 .owner = THIS_MODULE,
2018 .init = subflow_ulp_init,
2019 .release = subflow_ulp_release,
2020 .clone = subflow_ulp_clone,
2021};
2022
2023static int subflow_ops_init(struct request_sock_ops *subflow_ops)
2024{
2025 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
2026
2027 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
2028 subflow_ops->obj_size, 0,
2029 SLAB_ACCOUNT |
2030 SLAB_TYPESAFE_BY_RCU,
2031 NULL);
2032 if (!subflow_ops->slab)
2033 return -ENOMEM;
2034
2035 return 0;
2036}
2037
2038void __init mptcp_subflow_init(void)
2039{
2040 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
2041 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
2042 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
2043
2044 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
2045 panic("MPTCP: failed to init subflow v4 request sock ops\n");
2046
2047 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
2048 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
2049 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
2050
2051 subflow_specific = ipv4_specific;
2052 subflow_specific.conn_request = subflow_v4_conn_request;
2053 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
2054 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
2055 subflow_specific.rebuild_header = subflow_rebuild_header;
2056
2057 tcp_prot_override = tcp_prot;
2058 tcp_prot_override.release_cb = tcp_release_cb_override;
2059 tcp_prot_override.diag_destroy = tcp_abort_override;
2060
2061#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2062 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock
2063 * structures for v4 and v6 have the same size. It should not changed in
2064 * the future but better to make sure to be warned if it is no longer
2065 * the case.
2066 */
2067 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
2068
2069 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
2070 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
2071 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
2072
2073 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
2074 panic("MPTCP: failed to init subflow v6 request sock ops\n");
2075
2076 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
2077 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
2078 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
2079
2080 subflow_v6_specific = ipv6_specific;
2081 subflow_v6_specific.conn_request = subflow_v6_conn_request;
2082 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
2083 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
2084 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
2085
2086 subflow_v6m_specific = subflow_v6_specific;
2087 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
2088 subflow_v6m_specific.send_check = ipv4_specific.send_check;
2089 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
2090 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
2091 subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
2092
2093 tcpv6_prot_override = tcpv6_prot;
2094 tcpv6_prot_override.release_cb = tcp_release_cb_override;
2095 tcpv6_prot_override.diag_destroy = tcp_abort_override;
2096#endif
2097
2098 mptcp_diag_subflow_init(&subflow_ulp_ops);
2099
2100 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
2101 panic("MPTCP: failed to register subflows to ULP\n");
2102}