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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}
49
50static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
51 void *hmac)
52{
53 u8 msg[8];
54
55 put_unaligned_be32(nonce1, &msg[0]);
56 put_unaligned_be32(nonce2, &msg[4]);
57
58 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
59}
60
61static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
62{
63 return mptcp_is_fully_established((void *)msk) &&
64 ((mptcp_pm_is_userspace(msk) &&
65 mptcp_userspace_pm_active(msk)) ||
66 READ_ONCE(msk->pm.accept_subflow));
67}
68
69/* validate received token and create truncated hmac and nonce for SYN-ACK */
70static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
71{
72 struct mptcp_sock *msk = subflow_req->msk;
73 u8 hmac[SHA256_DIGEST_SIZE];
74
75 get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
76
77 subflow_generate_hmac(msk->local_key, msk->remote_key,
78 subflow_req->local_nonce,
79 subflow_req->remote_nonce, hmac);
80
81 subflow_req->thmac = get_unaligned_be64(hmac);
82}
83
84static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
85{
86 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
87 struct mptcp_sock *msk;
88 int local_id;
89
90 msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
91 if (!msk) {
92 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
93 return NULL;
94 }
95
96 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
97 if (local_id < 0) {
98 sock_put((struct sock *)msk);
99 return NULL;
100 }
101 subflow_req->local_id = local_id;
102
103 return msk;
104}
105
106static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
107{
108 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
109
110 subflow_req->mp_capable = 0;
111 subflow_req->mp_join = 0;
112 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
113 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
114 subflow_req->msk = NULL;
115 mptcp_token_init_request(req);
116}
117
118static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
119{
120 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
121}
122
123static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
124{
125 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
126
127 if (mpext) {
128 memset(mpext, 0, sizeof(*mpext));
129 mpext->reset_reason = reason;
130 }
131}
132
133/* Init mptcp request socket.
134 *
135 * Returns an error code if a JOIN has failed and a TCP reset
136 * should be sent.
137 */
138static int subflow_check_req(struct request_sock *req,
139 const struct sock *sk_listener,
140 struct sk_buff *skb)
141{
142 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
143 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
144 struct mptcp_options_received mp_opt;
145 bool opt_mp_capable, opt_mp_join;
146
147 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
148
149#ifdef CONFIG_TCP_MD5SIG
150 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
151 * TCP option space.
152 */
153 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
154 return -EINVAL;
155#endif
156
157 mptcp_get_options(skb, &mp_opt);
158
159 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
160 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
161 if (opt_mp_capable) {
162 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
163
164 if (opt_mp_join)
165 return 0;
166 } else if (opt_mp_join) {
167 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
168 }
169
170 if (opt_mp_capable && listener->request_mptcp) {
171 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
172
173 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
174again:
175 do {
176 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
177 } while (subflow_req->local_key == 0);
178
179 if (unlikely(req->syncookie)) {
180 mptcp_crypto_key_sha(subflow_req->local_key,
181 &subflow_req->token,
182 &subflow_req->idsn);
183 if (mptcp_token_exists(subflow_req->token)) {
184 if (retries-- > 0)
185 goto again;
186 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
187 } else {
188 subflow_req->mp_capable = 1;
189 }
190 return 0;
191 }
192
193 err = mptcp_token_new_request(req);
194 if (err == 0)
195 subflow_req->mp_capable = 1;
196 else if (retries-- > 0)
197 goto again;
198 else
199 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
200
201 } else if (opt_mp_join && listener->request_mptcp) {
202 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
203 subflow_req->mp_join = 1;
204 subflow_req->backup = mp_opt.backup;
205 subflow_req->remote_id = mp_opt.join_id;
206 subflow_req->token = mp_opt.token;
207 subflow_req->remote_nonce = mp_opt.nonce;
208 subflow_req->msk = subflow_token_join_request(req);
209
210 /* Can't fall back to TCP in this case. */
211 if (!subflow_req->msk) {
212 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
213 return -EPERM;
214 }
215
216 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
217 pr_debug("syn inet_sport=%d %d",
218 ntohs(inet_sk(sk_listener)->inet_sport),
219 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
220 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
221 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
222 return -EPERM;
223 }
224 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
225 }
226
227 subflow_req_create_thmac(subflow_req);
228
229 if (unlikely(req->syncookie)) {
230 if (mptcp_can_accept_new_subflow(subflow_req->msk))
231 subflow_init_req_cookie_join_save(subflow_req, skb);
232 else
233 return -EPERM;
234 }
235
236 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
237 subflow_req->remote_nonce, subflow_req->msk);
238 }
239
240 return 0;
241}
242
243int mptcp_subflow_init_cookie_req(struct request_sock *req,
244 const struct sock *sk_listener,
245 struct sk_buff *skb)
246{
247 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
248 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
249 struct mptcp_options_received mp_opt;
250 bool opt_mp_capable, opt_mp_join;
251 int err;
252
253 subflow_init_req(req, sk_listener);
254 mptcp_get_options(skb, &mp_opt);
255
256 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
257 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
258 if (opt_mp_capable && opt_mp_join)
259 return -EINVAL;
260
261 if (opt_mp_capable && listener->request_mptcp) {
262 if (mp_opt.sndr_key == 0)
263 return -EINVAL;
264
265 subflow_req->local_key = mp_opt.rcvr_key;
266 err = mptcp_token_new_request(req);
267 if (err)
268 return err;
269
270 subflow_req->mp_capable = 1;
271 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
272 } else if (opt_mp_join && listener->request_mptcp) {
273 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
274 return -EINVAL;
275
276 subflow_req->mp_join = 1;
277 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
278 }
279
280 return 0;
281}
282EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
283
284static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
285 struct sk_buff *skb,
286 struct flowi *fl,
287 struct request_sock *req)
288{
289 struct dst_entry *dst;
290 int err;
291
292 tcp_rsk(req)->is_mptcp = 1;
293 subflow_init_req(req, sk);
294
295 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
296 if (!dst)
297 return NULL;
298
299 err = subflow_check_req(req, sk, skb);
300 if (err == 0)
301 return dst;
302
303 dst_release(dst);
304 if (!req->syncookie)
305 tcp_request_sock_ops.send_reset(sk, skb);
306 return NULL;
307}
308
309static void subflow_prep_synack(const struct sock *sk, struct request_sock *req,
310 struct tcp_fastopen_cookie *foc,
311 enum tcp_synack_type synack_type)
312{
313 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
314 struct inet_request_sock *ireq = inet_rsk(req);
315
316 /* clear tstamp_ok, as needed depending on cookie */
317 if (foc && foc->len > -1)
318 ireq->tstamp_ok = 0;
319
320 if (synack_type == TCP_SYNACK_FASTOPEN)
321 mptcp_fastopen_subflow_synack_set_params(subflow, req);
322}
323
324static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
325 struct flowi *fl,
326 struct request_sock *req,
327 struct tcp_fastopen_cookie *foc,
328 enum tcp_synack_type synack_type,
329 struct sk_buff *syn_skb)
330{
331 subflow_prep_synack(sk, req, foc, synack_type);
332
333 return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc,
334 synack_type, syn_skb);
335}
336
337#if IS_ENABLED(CONFIG_MPTCP_IPV6)
338static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
339 struct flowi *fl,
340 struct request_sock *req,
341 struct tcp_fastopen_cookie *foc,
342 enum tcp_synack_type synack_type,
343 struct sk_buff *syn_skb)
344{
345 subflow_prep_synack(sk, req, foc, synack_type);
346
347 return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc,
348 synack_type, syn_skb);
349}
350
351static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
352 struct sk_buff *skb,
353 struct flowi *fl,
354 struct request_sock *req)
355{
356 struct dst_entry *dst;
357 int err;
358
359 tcp_rsk(req)->is_mptcp = 1;
360 subflow_init_req(req, sk);
361
362 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
363 if (!dst)
364 return NULL;
365
366 err = subflow_check_req(req, sk, skb);
367 if (err == 0)
368 return dst;
369
370 dst_release(dst);
371 if (!req->syncookie)
372 tcp6_request_sock_ops.send_reset(sk, skb);
373 return NULL;
374}
375#endif
376
377/* validate received truncated hmac and create hmac for third ACK */
378static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
379{
380 u8 hmac[SHA256_DIGEST_SIZE];
381 u64 thmac;
382
383 subflow_generate_hmac(subflow->remote_key, subflow->local_key,
384 subflow->remote_nonce, subflow->local_nonce,
385 hmac);
386
387 thmac = get_unaligned_be64(hmac);
388 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
389 subflow, subflow->token, thmac, subflow->thmac);
390
391 return thmac == subflow->thmac;
392}
393
394void mptcp_subflow_reset(struct sock *ssk)
395{
396 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
397 struct sock *sk = subflow->conn;
398
399 /* must hold: tcp_done() could drop last reference on parent */
400 sock_hold(sk);
401
402 tcp_set_state(ssk, TCP_CLOSE);
403 tcp_send_active_reset(ssk, GFP_ATOMIC);
404 tcp_done(ssk);
405 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
406 schedule_work(&mptcp_sk(sk)->work))
407 return; /* worker will put sk for us */
408
409 sock_put(sk);
410}
411
412static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
413{
414 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
415}
416
417void __mptcp_set_connected(struct sock *sk)
418{
419 if (sk->sk_state == TCP_SYN_SENT) {
420 inet_sk_state_store(sk, TCP_ESTABLISHED);
421 sk->sk_state_change(sk);
422 }
423}
424
425static void mptcp_set_connected(struct sock *sk)
426{
427 mptcp_data_lock(sk);
428 if (!sock_owned_by_user(sk))
429 __mptcp_set_connected(sk);
430 else
431 __set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->cb_flags);
432 mptcp_data_unlock(sk);
433}
434
435static void subflow_set_remote_key(struct mptcp_sock *msk,
436 struct mptcp_subflow_context *subflow,
437 const struct mptcp_options_received *mp_opt)
438{
439 /* active MPC subflow will reach here multiple times:
440 * at subflow_finish_connect() time and at 4th ack time
441 */
442 if (subflow->remote_key_valid)
443 return;
444
445 subflow->remote_key_valid = 1;
446 subflow->remote_key = mp_opt->sndr_key;
447 mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
448 subflow->iasn++;
449
450 WRITE_ONCE(msk->remote_key, subflow->remote_key);
451 WRITE_ONCE(msk->ack_seq, subflow->iasn);
452 WRITE_ONCE(msk->can_ack, true);
453 atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
454}
455
456static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
457{
458 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
459 struct mptcp_options_received mp_opt;
460 struct sock *parent = subflow->conn;
461 struct mptcp_sock *msk;
462
463 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
464
465 /* be sure no special action on any packet other than syn-ack */
466 if (subflow->conn_finished)
467 return;
468
469 msk = mptcp_sk(parent);
470 mptcp_propagate_sndbuf(parent, sk);
471 subflow->rel_write_seq = 1;
472 subflow->conn_finished = 1;
473 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
474 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
475
476 mptcp_get_options(skb, &mp_opt);
477 if (subflow->request_mptcp) {
478 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
479 MPTCP_INC_STATS(sock_net(sk),
480 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
481 mptcp_do_fallback(sk);
482 pr_fallback(msk);
483 goto fallback;
484 }
485
486 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
487 WRITE_ONCE(msk->csum_enabled, true);
488 if (mp_opt.deny_join_id0)
489 WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
490 subflow->mp_capable = 1;
491 subflow_set_remote_key(msk, subflow, &mp_opt);
492 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
493 mptcp_finish_connect(sk);
494 mptcp_set_connected(parent);
495 } else if (subflow->request_join) {
496 u8 hmac[SHA256_DIGEST_SIZE];
497
498 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) {
499 subflow->reset_reason = MPTCP_RST_EMPTCP;
500 goto do_reset;
501 }
502
503 subflow->backup = mp_opt.backup;
504 subflow->thmac = mp_opt.thmac;
505 subflow->remote_nonce = mp_opt.nonce;
506 subflow->remote_id = mp_opt.join_id;
507 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
508 subflow, subflow->thmac, subflow->remote_nonce,
509 subflow->backup);
510
511 if (!subflow_thmac_valid(subflow)) {
512 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
513 subflow->reset_reason = MPTCP_RST_EMPTCP;
514 goto do_reset;
515 }
516
517 if (!mptcp_finish_join(sk))
518 goto do_reset;
519
520 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
521 subflow->local_nonce,
522 subflow->remote_nonce,
523 hmac);
524 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
525
526 subflow->mp_join = 1;
527 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
528
529 if (subflow_use_different_dport(msk, sk)) {
530 pr_debug("synack inet_dport=%d %d",
531 ntohs(inet_sk(sk)->inet_dport),
532 ntohs(inet_sk(parent)->inet_dport));
533 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
534 }
535 } else if (mptcp_check_fallback(sk)) {
536fallback:
537 mptcp_rcv_space_init(msk, sk);
538 mptcp_set_connected(parent);
539 }
540 return;
541
542do_reset:
543 subflow->reset_transient = 0;
544 mptcp_subflow_reset(sk);
545}
546
547static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
548{
549 subflow->local_id = local_id;
550 subflow->local_id_valid = 1;
551}
552
553static int subflow_chk_local_id(struct sock *sk)
554{
555 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
556 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
557 int err;
558
559 if (likely(subflow->local_id_valid))
560 return 0;
561
562 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
563 if (err < 0)
564 return err;
565
566 subflow_set_local_id(subflow, err);
567 return 0;
568}
569
570static int subflow_rebuild_header(struct sock *sk)
571{
572 int err = subflow_chk_local_id(sk);
573
574 if (unlikely(err < 0))
575 return err;
576
577 return inet_sk_rebuild_header(sk);
578}
579
580#if IS_ENABLED(CONFIG_MPTCP_IPV6)
581static int subflow_v6_rebuild_header(struct sock *sk)
582{
583 int err = subflow_chk_local_id(sk);
584
585 if (unlikely(err < 0))
586 return err;
587
588 return inet6_sk_rebuild_header(sk);
589}
590#endif
591
592static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
593static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
594
595static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
596{
597 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
598
599 pr_debug("subflow=%p", subflow);
600
601 /* Never answer to SYNs sent to broadcast or multicast */
602 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
603 goto drop;
604
605 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
606 &subflow_request_sock_ipv4_ops,
607 sk, skb);
608drop:
609 tcp_listendrop(sk);
610 return 0;
611}
612
613static void subflow_v4_req_destructor(struct request_sock *req)
614{
615 subflow_req_destructor(req);
616 tcp_request_sock_ops.destructor(req);
617}
618
619#if IS_ENABLED(CONFIG_MPTCP_IPV6)
620static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
621static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
622static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
623static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
624static struct proto tcpv6_prot_override;
625
626static int subflow_v6_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 if (skb->protocol == htons(ETH_P_IP))
633 return subflow_v4_conn_request(sk, skb);
634
635 if (!ipv6_unicast_destination(skb))
636 goto drop;
637
638 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
639 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
640 return 0;
641 }
642
643 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
644 &subflow_request_sock_ipv6_ops, sk, skb);
645
646drop:
647 tcp_listendrop(sk);
648 return 0; /* don't send reset */
649}
650
651static void subflow_v6_req_destructor(struct request_sock *req)
652{
653 subflow_req_destructor(req);
654 tcp6_request_sock_ops.destructor(req);
655}
656#endif
657
658struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
659 struct sock *sk_listener,
660 bool attach_listener)
661{
662 if (ops->family == AF_INET)
663 ops = &mptcp_subflow_v4_request_sock_ops;
664#if IS_ENABLED(CONFIG_MPTCP_IPV6)
665 else if (ops->family == AF_INET6)
666 ops = &mptcp_subflow_v6_request_sock_ops;
667#endif
668
669 return inet_reqsk_alloc(ops, sk_listener, attach_listener);
670}
671EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
672
673/* validate hmac received in third ACK */
674static bool subflow_hmac_valid(const struct request_sock *req,
675 const struct mptcp_options_received *mp_opt)
676{
677 const struct mptcp_subflow_request_sock *subflow_req;
678 u8 hmac[SHA256_DIGEST_SIZE];
679 struct mptcp_sock *msk;
680
681 subflow_req = mptcp_subflow_rsk(req);
682 msk = subflow_req->msk;
683 if (!msk)
684 return false;
685
686 subflow_generate_hmac(msk->remote_key, msk->local_key,
687 subflow_req->remote_nonce,
688 subflow_req->local_nonce, hmac);
689
690 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
691}
692
693static void mptcp_force_close(struct sock *sk)
694{
695 /* the msk is not yet exposed to user-space */
696 inet_sk_state_store(sk, TCP_CLOSE);
697 sk_common_release(sk);
698}
699
700static void subflow_ulp_fallback(struct sock *sk,
701 struct mptcp_subflow_context *old_ctx)
702{
703 struct inet_connection_sock *icsk = inet_csk(sk);
704
705 mptcp_subflow_tcp_fallback(sk, old_ctx);
706 icsk->icsk_ulp_ops = NULL;
707 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
708 tcp_sk(sk)->is_mptcp = 0;
709
710 mptcp_subflow_ops_undo_override(sk);
711}
712
713static void subflow_drop_ctx(struct sock *ssk)
714{
715 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
716
717 if (!ctx)
718 return;
719
720 subflow_ulp_fallback(ssk, ctx);
721 if (ctx->conn)
722 sock_put(ctx->conn);
723
724 kfree_rcu(ctx, rcu);
725}
726
727void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
728 const struct mptcp_options_received *mp_opt)
729{
730 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
731
732 subflow_set_remote_key(msk, subflow, mp_opt);
733 subflow->fully_established = 1;
734 WRITE_ONCE(msk->fully_established, true);
735
736 if (subflow->is_mptfo)
737 mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt);
738}
739
740static struct sock *subflow_syn_recv_sock(const struct sock *sk,
741 struct sk_buff *skb,
742 struct request_sock *req,
743 struct dst_entry *dst,
744 struct request_sock *req_unhash,
745 bool *own_req)
746{
747 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
748 struct mptcp_subflow_request_sock *subflow_req;
749 struct mptcp_options_received mp_opt;
750 bool fallback, fallback_is_fatal;
751 struct sock *new_msk = NULL;
752 struct sock *child;
753
754 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
755
756 /* After child creation we must look for MPC even when options
757 * are not parsed
758 */
759 mp_opt.suboptions = 0;
760
761 /* hopefully temporary handling for MP_JOIN+syncookie */
762 subflow_req = mptcp_subflow_rsk(req);
763 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
764 fallback = !tcp_rsk(req)->is_mptcp;
765 if (fallback)
766 goto create_child;
767
768 /* if the sk is MP_CAPABLE, we try to fetch the client key */
769 if (subflow_req->mp_capable) {
770 /* we can receive and accept an in-window, out-of-order pkt,
771 * which may not carry the MP_CAPABLE opt even on mptcp enabled
772 * paths: always try to extract the peer key, and fallback
773 * for packets missing it.
774 * Even OoO DSS packets coming legitly after dropped or
775 * reordered MPC will cause fallback, but we don't have other
776 * options.
777 */
778 mptcp_get_options(skb, &mp_opt);
779 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
780 fallback = true;
781 goto create_child;
782 }
783
784 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
785 if (!new_msk)
786 fallback = true;
787 } else if (subflow_req->mp_join) {
788 mptcp_get_options(skb, &mp_opt);
789 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||
790 !subflow_hmac_valid(req, &mp_opt) ||
791 !mptcp_can_accept_new_subflow(subflow_req->msk)) {
792 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
793 fallback = true;
794 }
795 }
796
797create_child:
798 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
799 req_unhash, own_req);
800
801 if (child && *own_req) {
802 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
803
804 tcp_rsk(req)->drop_req = false;
805
806 /* we need to fallback on ctx allocation failure and on pre-reqs
807 * checking above. In the latter scenario we additionally need
808 * to reset the context to non MPTCP status.
809 */
810 if (!ctx || fallback) {
811 if (fallback_is_fatal) {
812 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
813 goto dispose_child;
814 }
815
816 if (new_msk)
817 mptcp_copy_inaddrs(new_msk, child);
818 subflow_drop_ctx(child);
819 goto out;
820 }
821
822 /* ssk inherits options of listener sk */
823 ctx->setsockopt_seq = listener->setsockopt_seq;
824
825 if (ctx->mp_capable) {
826 /* this can't race with mptcp_close(), as the msk is
827 * not yet exposted to user-space
828 */
829 inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
830
831 /* record the newly created socket as the first msk
832 * subflow, but don't link it yet into conn_list
833 */
834 WRITE_ONCE(mptcp_sk(new_msk)->first, child);
835
836 /* new mpc subflow takes ownership of the newly
837 * created mptcp socket
838 */
839 mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
840 mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
841 mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
842 ctx->conn = new_msk;
843 new_msk = NULL;
844
845 /* set msk addresses early to ensure mptcp_pm_get_local_id()
846 * uses the correct data
847 */
848 mptcp_copy_inaddrs(ctx->conn, child);
849
850 /* with OoO packets we can reach here without ingress
851 * mpc option
852 */
853 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK)
854 mptcp_subflow_fully_established(ctx, &mp_opt);
855 } else if (ctx->mp_join) {
856 struct mptcp_sock *owner;
857
858 owner = subflow_req->msk;
859 if (!owner) {
860 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
861 goto dispose_child;
862 }
863
864 /* move the msk reference ownership to the subflow */
865 subflow_req->msk = NULL;
866 ctx->conn = (struct sock *)owner;
867
868 if (subflow_use_different_sport(owner, sk)) {
869 pr_debug("ack inet_sport=%d %d",
870 ntohs(inet_sk(sk)->inet_sport),
871 ntohs(inet_sk((struct sock *)owner)->inet_sport));
872 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
873 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
874 goto dispose_child;
875 }
876 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
877 }
878
879 if (!mptcp_finish_join(child))
880 goto dispose_child;
881
882 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
883 tcp_rsk(req)->drop_req = true;
884 }
885 }
886
887out:
888 /* dispose of the left over mptcp master, if any */
889 if (unlikely(new_msk))
890 mptcp_force_close(new_msk);
891
892 /* check for expected invariant - should never trigger, just help
893 * catching eariler subtle bugs
894 */
895 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
896 (!mptcp_subflow_ctx(child) ||
897 !mptcp_subflow_ctx(child)->conn));
898 return child;
899
900dispose_child:
901 subflow_drop_ctx(child);
902 tcp_rsk(req)->drop_req = true;
903 inet_csk_prepare_for_destroy_sock(child);
904 tcp_done(child);
905 req->rsk_ops->send_reset(sk, skb);
906
907 /* The last child reference will be released by the caller */
908 return child;
909}
910
911static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
912static struct proto tcp_prot_override;
913
914enum mapping_status {
915 MAPPING_OK,
916 MAPPING_INVALID,
917 MAPPING_EMPTY,
918 MAPPING_DATA_FIN,
919 MAPPING_DUMMY,
920 MAPPING_BAD_CSUM
921};
922
923static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
924{
925 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
926 ssn, subflow->map_subflow_seq, subflow->map_data_len);
927}
928
929static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
930{
931 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
932 unsigned int skb_consumed;
933
934 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
935 if (WARN_ON_ONCE(skb_consumed >= skb->len))
936 return true;
937
938 return skb->len - skb_consumed <= subflow->map_data_len -
939 mptcp_subflow_get_map_offset(subflow);
940}
941
942static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
943{
944 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
945 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
946
947 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
948 /* Mapping covers data later in the subflow stream,
949 * currently unsupported.
950 */
951 dbg_bad_map(subflow, ssn);
952 return false;
953 }
954 if (unlikely(!before(ssn, subflow->map_subflow_seq +
955 subflow->map_data_len))) {
956 /* Mapping does covers past subflow data, invalid */
957 dbg_bad_map(subflow, ssn);
958 return false;
959 }
960 return true;
961}
962
963static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
964 bool csum_reqd)
965{
966 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
967 u32 offset, seq, delta;
968 __sum16 csum;
969 int len;
970
971 if (!csum_reqd)
972 return MAPPING_OK;
973
974 /* mapping already validated on previous traversal */
975 if (subflow->map_csum_len == subflow->map_data_len)
976 return MAPPING_OK;
977
978 /* traverse the receive queue, ensuring it contains a full
979 * DSS mapping and accumulating the related csum.
980 * Preserve the accoumlate csum across multiple calls, to compute
981 * the csum only once
982 */
983 delta = subflow->map_data_len - subflow->map_csum_len;
984 for (;;) {
985 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
986 offset = seq - TCP_SKB_CB(skb)->seq;
987
988 /* if the current skb has not been accounted yet, csum its contents
989 * up to the amount covered by the current DSS
990 */
991 if (offset < skb->len) {
992 __wsum csum;
993
994 len = min(skb->len - offset, delta);
995 csum = skb_checksum(skb, offset, len, 0);
996 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
997 subflow->map_csum_len);
998
999 delta -= len;
1000 subflow->map_csum_len += len;
1001 }
1002 if (delta == 0)
1003 break;
1004
1005 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
1006 /* if this subflow is closed, the partial mapping
1007 * will be never completed; flush the pending skbs, so
1008 * that subflow_sched_work_if_closed() can kick in
1009 */
1010 if (unlikely(ssk->sk_state == TCP_CLOSE))
1011 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1012 sk_eat_skb(ssk, skb);
1013
1014 /* not enough data to validate the csum */
1015 return MAPPING_EMPTY;
1016 }
1017
1018 /* the DSS mapping for next skbs will be validated later,
1019 * when a get_mapping_status call will process such skb
1020 */
1021 skb = skb->next;
1022 }
1023
1024 /* note that 'map_data_len' accounts only for the carried data, does
1025 * not include the eventual seq increment due to the data fin,
1026 * while the pseudo header requires the original DSS data len,
1027 * including that
1028 */
1029 csum = __mptcp_make_csum(subflow->map_seq,
1030 subflow->map_subflow_seq,
1031 subflow->map_data_len + subflow->map_data_fin,
1032 subflow->map_data_csum);
1033 if (unlikely(csum)) {
1034 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
1035 return MAPPING_BAD_CSUM;
1036 }
1037
1038 subflow->valid_csum_seen = 1;
1039 return MAPPING_OK;
1040}
1041
1042static enum mapping_status get_mapping_status(struct sock *ssk,
1043 struct mptcp_sock *msk)
1044{
1045 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1046 bool csum_reqd = READ_ONCE(msk->csum_enabled);
1047 struct mptcp_ext *mpext;
1048 struct sk_buff *skb;
1049 u16 data_len;
1050 u64 map_seq;
1051
1052 skb = skb_peek(&ssk->sk_receive_queue);
1053 if (!skb)
1054 return MAPPING_EMPTY;
1055
1056 if (mptcp_check_fallback(ssk))
1057 return MAPPING_DUMMY;
1058
1059 mpext = mptcp_get_ext(skb);
1060 if (!mpext || !mpext->use_map) {
1061 if (!subflow->map_valid && !skb->len) {
1062 /* the TCP stack deliver 0 len FIN pkt to the receive
1063 * queue, that is the only 0len pkts ever expected here,
1064 * and we can admit no mapping only for 0 len pkts
1065 */
1066 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
1067 WARN_ONCE(1, "0len seq %d:%d flags %x",
1068 TCP_SKB_CB(skb)->seq,
1069 TCP_SKB_CB(skb)->end_seq,
1070 TCP_SKB_CB(skb)->tcp_flags);
1071 sk_eat_skb(ssk, skb);
1072 return MAPPING_EMPTY;
1073 }
1074
1075 if (!subflow->map_valid)
1076 return MAPPING_INVALID;
1077
1078 goto validate_seq;
1079 }
1080
1081 trace_get_mapping_status(mpext);
1082
1083 data_len = mpext->data_len;
1084 if (data_len == 0) {
1085 pr_debug("infinite mapping received");
1086 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
1087 subflow->map_data_len = 0;
1088 return MAPPING_INVALID;
1089 }
1090
1091 if (mpext->data_fin == 1) {
1092 if (data_len == 1) {
1093 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
1094 mpext->dsn64);
1095 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
1096 if (subflow->map_valid) {
1097 /* A DATA_FIN might arrive in a DSS
1098 * option before the previous mapping
1099 * has been fully consumed. Continue
1100 * handling the existing mapping.
1101 */
1102 skb_ext_del(skb, SKB_EXT_MPTCP);
1103 return MAPPING_OK;
1104 } else {
1105 if (updated && schedule_work(&msk->work))
1106 sock_hold((struct sock *)msk);
1107
1108 return MAPPING_DATA_FIN;
1109 }
1110 } else {
1111 u64 data_fin_seq = mpext->data_seq + data_len - 1;
1112
1113 /* If mpext->data_seq is a 32-bit value, data_fin_seq
1114 * must also be limited to 32 bits.
1115 */
1116 if (!mpext->dsn64)
1117 data_fin_seq &= GENMASK_ULL(31, 0);
1118
1119 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1120 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
1121 data_fin_seq, mpext->dsn64);
1122 }
1123
1124 /* Adjust for DATA_FIN using 1 byte of sequence space */
1125 data_len--;
1126 }
1127
1128 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1129 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1130
1131 if (subflow->map_valid) {
1132 /* Allow replacing only with an identical map */
1133 if (subflow->map_seq == map_seq &&
1134 subflow->map_subflow_seq == mpext->subflow_seq &&
1135 subflow->map_data_len == data_len &&
1136 subflow->map_csum_reqd == mpext->csum_reqd) {
1137 skb_ext_del(skb, SKB_EXT_MPTCP);
1138 goto validate_csum;
1139 }
1140
1141 /* If this skb data are fully covered by the current mapping,
1142 * the new map would need caching, which is not supported
1143 */
1144 if (skb_is_fully_mapped(ssk, skb)) {
1145 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1146 return MAPPING_INVALID;
1147 }
1148
1149 /* will validate the next map after consuming the current one */
1150 goto validate_csum;
1151 }
1152
1153 subflow->map_seq = map_seq;
1154 subflow->map_subflow_seq = mpext->subflow_seq;
1155 subflow->map_data_len = data_len;
1156 subflow->map_valid = 1;
1157 subflow->map_data_fin = mpext->data_fin;
1158 subflow->mpc_map = mpext->mpc_map;
1159 subflow->map_csum_reqd = mpext->csum_reqd;
1160 subflow->map_csum_len = 0;
1161 subflow->map_data_csum = csum_unfold(mpext->csum);
1162
1163 /* Cfr RFC 8684 Section 3.3.0 */
1164 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1165 return MAPPING_INVALID;
1166
1167 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1168 subflow->map_seq, subflow->map_subflow_seq,
1169 subflow->map_data_len, subflow->map_csum_reqd,
1170 subflow->map_data_csum);
1171
1172validate_seq:
1173 /* we revalidate valid mapping on new skb, because we must ensure
1174 * the current skb is completely covered by the available mapping
1175 */
1176 if (!validate_mapping(ssk, skb)) {
1177 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1178 return MAPPING_INVALID;
1179 }
1180
1181 skb_ext_del(skb, SKB_EXT_MPTCP);
1182
1183validate_csum:
1184 return validate_data_csum(ssk, skb, csum_reqd);
1185}
1186
1187static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1188 u64 limit)
1189{
1190 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1191 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1192 u32 incr;
1193
1194 incr = limit >= skb->len ? skb->len + fin : limit;
1195
1196 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1197 subflow->map_subflow_seq);
1198 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1199 tcp_sk(ssk)->copied_seq += incr;
1200 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1201 sk_eat_skb(ssk, skb);
1202 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1203 subflow->map_valid = 0;
1204}
1205
1206/* sched mptcp worker to remove the subflow if no more data is pending */
1207static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1208{
1209 struct sock *sk = (struct sock *)msk;
1210
1211 if (likely(ssk->sk_state != TCP_CLOSE))
1212 return;
1213
1214 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1215 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
1216 sock_hold(sk);
1217 if (!schedule_work(&msk->work))
1218 sock_put(sk);
1219 }
1220}
1221
1222static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
1223{
1224 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1225
1226 if (subflow->mp_join)
1227 return false;
1228 else if (READ_ONCE(msk->csum_enabled))
1229 return !subflow->valid_csum_seen;
1230 else
1231 return !subflow->fully_established;
1232}
1233
1234static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1235{
1236 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1237 unsigned long fail_tout;
1238
1239 /* greceful failure can happen only on the MPC subflow */
1240 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1241 return;
1242
1243 /* since the close timeout take precedence on the fail one,
1244 * no need to start the latter when the first is already set
1245 */
1246 if (sock_flag((struct sock *)msk, SOCK_DEAD))
1247 return;
1248
1249 /* we don't need extreme accuracy here, use a zero fail_tout as special
1250 * value meaning no fail timeout at all;
1251 */
1252 fail_tout = jiffies + TCP_RTO_MAX;
1253 if (!fail_tout)
1254 fail_tout = 1;
1255 WRITE_ONCE(subflow->fail_tout, fail_tout);
1256 tcp_send_ack(ssk);
1257
1258 mptcp_reset_timeout(msk, subflow->fail_tout);
1259}
1260
1261static bool subflow_check_data_avail(struct sock *ssk)
1262{
1263 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1264 enum mapping_status status;
1265 struct mptcp_sock *msk;
1266 struct sk_buff *skb;
1267
1268 if (!skb_peek(&ssk->sk_receive_queue))
1269 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1270 if (subflow->data_avail)
1271 return true;
1272
1273 msk = mptcp_sk(subflow->conn);
1274 for (;;) {
1275 u64 ack_seq;
1276 u64 old_ack;
1277
1278 status = get_mapping_status(ssk, msk);
1279 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1280 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1281 status == MAPPING_BAD_CSUM))
1282 goto fallback;
1283
1284 if (status != MAPPING_OK)
1285 goto no_data;
1286
1287 skb = skb_peek(&ssk->sk_receive_queue);
1288 if (WARN_ON_ONCE(!skb))
1289 goto no_data;
1290
1291 if (unlikely(!READ_ONCE(msk->can_ack)))
1292 goto fallback;
1293
1294 old_ack = READ_ONCE(msk->ack_seq);
1295 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1296 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1297 ack_seq);
1298 if (unlikely(before64(ack_seq, old_ack))) {
1299 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1300 continue;
1301 }
1302
1303 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1304 break;
1305 }
1306 return true;
1307
1308no_data:
1309 subflow_sched_work_if_closed(msk, ssk);
1310 return false;
1311
1312fallback:
1313 if (!__mptcp_check_fallback(msk)) {
1314 /* RFC 8684 section 3.7. */
1315 if (status == MAPPING_BAD_CSUM &&
1316 (subflow->mp_join || subflow->valid_csum_seen)) {
1317 subflow->send_mp_fail = 1;
1318
1319 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1320 subflow->reset_transient = 0;
1321 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1322 goto reset;
1323 }
1324 mptcp_subflow_fail(msk, ssk);
1325 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1326 return true;
1327 }
1328
1329 if (!subflow_can_fallback(subflow) && subflow->map_data_len) {
1330 /* fatal protocol error, close the socket.
1331 * subflow_error_report() will introduce the appropriate barriers
1332 */
1333 subflow->reset_transient = 0;
1334 subflow->reset_reason = MPTCP_RST_EMPTCP;
1335
1336reset:
1337 ssk->sk_err = EBADMSG;
1338 tcp_set_state(ssk, TCP_CLOSE);
1339 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1340 sk_eat_skb(ssk, skb);
1341 tcp_send_active_reset(ssk, GFP_ATOMIC);
1342 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1343 return false;
1344 }
1345
1346 mptcp_do_fallback(ssk);
1347 }
1348
1349 skb = skb_peek(&ssk->sk_receive_queue);
1350 subflow->map_valid = 1;
1351 subflow->map_seq = READ_ONCE(msk->ack_seq);
1352 subflow->map_data_len = skb->len;
1353 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1354 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1355 return true;
1356}
1357
1358bool mptcp_subflow_data_available(struct sock *sk)
1359{
1360 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1361
1362 /* check if current mapping is still valid */
1363 if (subflow->map_valid &&
1364 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1365 subflow->map_valid = 0;
1366 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1367
1368 pr_debug("Done with mapping: seq=%u data_len=%u",
1369 subflow->map_subflow_seq,
1370 subflow->map_data_len);
1371 }
1372
1373 return subflow_check_data_avail(sk);
1374}
1375
1376/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1377 * not the ssk one.
1378 *
1379 * In mptcp, rwin is about the mptcp-level connection data.
1380 *
1381 * Data that is still on the ssk rx queue can thus be ignored,
1382 * as far as mptcp peer is concerned that data is still inflight.
1383 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1384 */
1385void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1386{
1387 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1388 const struct sock *sk = subflow->conn;
1389
1390 *space = __mptcp_space(sk);
1391 *full_space = tcp_full_space(sk);
1392}
1393
1394void __mptcp_error_report(struct sock *sk)
1395{
1396 struct mptcp_subflow_context *subflow;
1397 struct mptcp_sock *msk = mptcp_sk(sk);
1398
1399 mptcp_for_each_subflow(msk, subflow) {
1400 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1401 int err = sock_error(ssk);
1402 int ssk_state;
1403
1404 if (!err)
1405 continue;
1406
1407 /* only propagate errors on fallen-back sockets or
1408 * on MPC connect
1409 */
1410 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1411 continue;
1412
1413 /* We need to propagate only transition to CLOSE state.
1414 * Orphaned socket will see such state change via
1415 * subflow_sched_work_if_closed() and that path will properly
1416 * destroy the msk as needed.
1417 */
1418 ssk_state = inet_sk_state_load(ssk);
1419 if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
1420 inet_sk_state_store(sk, ssk_state);
1421 sk->sk_err = -err;
1422
1423 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1424 smp_wmb();
1425 sk_error_report(sk);
1426 break;
1427 }
1428}
1429
1430static void subflow_error_report(struct sock *ssk)
1431{
1432 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1433
1434 mptcp_data_lock(sk);
1435 if (!sock_owned_by_user(sk))
1436 __mptcp_error_report(sk);
1437 else
1438 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
1439 mptcp_data_unlock(sk);
1440}
1441
1442static void subflow_data_ready(struct sock *sk)
1443{
1444 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1445 u16 state = 1 << inet_sk_state_load(sk);
1446 struct sock *parent = subflow->conn;
1447 struct mptcp_sock *msk;
1448
1449 msk = mptcp_sk(parent);
1450 if (state & TCPF_LISTEN) {
1451 /* MPJ subflow are removed from accept queue before reaching here,
1452 * avoid stray wakeups
1453 */
1454 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1455 return;
1456
1457 parent->sk_data_ready(parent);
1458 return;
1459 }
1460
1461 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1462 !subflow->mp_join && !(state & TCPF_CLOSE));
1463
1464 if (mptcp_subflow_data_available(sk))
1465 mptcp_data_ready(parent, sk);
1466 else if (unlikely(sk->sk_err))
1467 subflow_error_report(sk);
1468}
1469
1470static void subflow_write_space(struct sock *ssk)
1471{
1472 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1473
1474 mptcp_propagate_sndbuf(sk, ssk);
1475 mptcp_write_space(sk);
1476}
1477
1478static const struct inet_connection_sock_af_ops *
1479subflow_default_af_ops(struct sock *sk)
1480{
1481#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1482 if (sk->sk_family == AF_INET6)
1483 return &subflow_v6_specific;
1484#endif
1485 return &subflow_specific;
1486}
1487
1488#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1489void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1490{
1491 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1492 struct inet_connection_sock *icsk = inet_csk(sk);
1493 const struct inet_connection_sock_af_ops *target;
1494
1495 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1496
1497 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1498 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1499
1500 if (likely(icsk->icsk_af_ops == target))
1501 return;
1502
1503 subflow->icsk_af_ops = icsk->icsk_af_ops;
1504 icsk->icsk_af_ops = target;
1505}
1506#endif
1507
1508void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1509 struct sockaddr_storage *addr,
1510 unsigned short family)
1511{
1512 memset(addr, 0, sizeof(*addr));
1513 addr->ss_family = family;
1514 if (addr->ss_family == AF_INET) {
1515 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1516
1517 if (info->family == AF_INET)
1518 in_addr->sin_addr = info->addr;
1519#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1520 else if (ipv6_addr_v4mapped(&info->addr6))
1521 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1522#endif
1523 in_addr->sin_port = info->port;
1524 }
1525#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1526 else if (addr->ss_family == AF_INET6) {
1527 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1528
1529 if (info->family == AF_INET)
1530 ipv6_addr_set_v4mapped(info->addr.s_addr,
1531 &in6_addr->sin6_addr);
1532 else
1533 in6_addr->sin6_addr = info->addr6;
1534 in6_addr->sin6_port = info->port;
1535 }
1536#endif
1537}
1538
1539int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1540 const struct mptcp_addr_info *remote)
1541{
1542 struct mptcp_sock *msk = mptcp_sk(sk);
1543 struct mptcp_subflow_context *subflow;
1544 struct sockaddr_storage addr;
1545 int remote_id = remote->id;
1546 int local_id = loc->id;
1547 int err = -ENOTCONN;
1548 struct socket *sf;
1549 struct sock *ssk;
1550 u32 remote_token;
1551 int addrlen;
1552 int ifindex;
1553 u8 flags;
1554
1555 if (!mptcp_is_fully_established(sk))
1556 goto err_out;
1557
1558 err = mptcp_subflow_create_socket(sk, loc->family, &sf);
1559 if (err)
1560 goto err_out;
1561
1562 ssk = sf->sk;
1563 subflow = mptcp_subflow_ctx(ssk);
1564 do {
1565 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1566 } while (!subflow->local_nonce);
1567
1568 if (local_id)
1569 subflow_set_local_id(subflow, local_id);
1570
1571 mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id,
1572 &flags, &ifindex);
1573 subflow->remote_key_valid = 1;
1574 subflow->remote_key = msk->remote_key;
1575 subflow->local_key = msk->local_key;
1576 subflow->token = msk->token;
1577 mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1578
1579 addrlen = sizeof(struct sockaddr_in);
1580#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1581 if (addr.ss_family == AF_INET6)
1582 addrlen = sizeof(struct sockaddr_in6);
1583#endif
1584 mptcp_sockopt_sync(msk, ssk);
1585
1586 ssk->sk_bound_dev_if = ifindex;
1587 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1588 if (err)
1589 goto failed;
1590
1591 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1592 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1593 remote_token, local_id, remote_id);
1594 subflow->remote_token = remote_token;
1595 subflow->remote_id = remote_id;
1596 subflow->request_join = 1;
1597 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1598 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1599
1600 sock_hold(ssk);
1601 list_add_tail(&subflow->node, &msk->conn_list);
1602 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1603 if (err && err != -EINPROGRESS)
1604 goto failed_unlink;
1605
1606 /* discard the subflow socket */
1607 mptcp_sock_graft(ssk, sk->sk_socket);
1608 iput(SOCK_INODE(sf));
1609 WRITE_ONCE(msk->allow_infinite_fallback, false);
1610 return 0;
1611
1612failed_unlink:
1613 list_del(&subflow->node);
1614 sock_put(mptcp_subflow_tcp_sock(subflow));
1615
1616failed:
1617 subflow->disposable = 1;
1618 sock_release(sf);
1619
1620err_out:
1621 /* we account subflows before the creation, and this failures will not
1622 * be caught by sk_state_change()
1623 */
1624 mptcp_pm_close_subflow(msk);
1625 return err;
1626}
1627
1628static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1629{
1630#ifdef CONFIG_SOCK_CGROUP_DATA
1631 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1632 *child_skcd = &child->sk_cgrp_data;
1633
1634 /* only the additional subflows created by kworkers have to be modified */
1635 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1636 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1637#ifdef CONFIG_MEMCG
1638 struct mem_cgroup *memcg = parent->sk_memcg;
1639
1640 mem_cgroup_sk_free(child);
1641 if (memcg && css_tryget(&memcg->css))
1642 child->sk_memcg = memcg;
1643#endif /* CONFIG_MEMCG */
1644
1645 cgroup_sk_free(child_skcd);
1646 *child_skcd = *parent_skcd;
1647 cgroup_sk_clone(child_skcd);
1648 }
1649#endif /* CONFIG_SOCK_CGROUP_DATA */
1650}
1651
1652static void mptcp_subflow_ops_override(struct sock *ssk)
1653{
1654#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1655 if (ssk->sk_prot == &tcpv6_prot)
1656 ssk->sk_prot = &tcpv6_prot_override;
1657 else
1658#endif
1659 ssk->sk_prot = &tcp_prot_override;
1660}
1661
1662static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1663{
1664#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1665 if (ssk->sk_prot == &tcpv6_prot_override)
1666 ssk->sk_prot = &tcpv6_prot;
1667 else
1668#endif
1669 ssk->sk_prot = &tcp_prot;
1670}
1671
1672int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1673 struct socket **new_sock)
1674{
1675 struct mptcp_subflow_context *subflow;
1676 struct net *net = sock_net(sk);
1677 struct socket *sf;
1678 int err;
1679
1680 /* un-accepted server sockets can reach here - on bad configuration
1681 * bail early to avoid greater trouble later
1682 */
1683 if (unlikely(!sk->sk_socket))
1684 return -EINVAL;
1685
1686 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
1687 if (err)
1688 return err;
1689
1690 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
1691
1692 /* the newly created socket has to be in the same cgroup as its parent */
1693 mptcp_attach_cgroup(sk, sf->sk);
1694
1695 /* kernel sockets do not by default acquire net ref, but TCP timer
1696 * needs it.
1697 * Update ns_tracker to current stack trace and refcounted tracker.
1698 */
1699 __netns_tracker_free(net, &sf->sk->ns_tracker, false);
1700 sf->sk->sk_net_refcnt = 1;
1701 get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL);
1702 sock_inuse_add(net, 1);
1703 err = tcp_set_ulp(sf->sk, "mptcp");
1704 release_sock(sf->sk);
1705
1706 if (err) {
1707 sock_release(sf);
1708 return err;
1709 }
1710
1711 /* the newly created socket really belongs to the owning MPTCP master
1712 * socket, even if for additional subflows the allocation is performed
1713 * by a kernel workqueue. Adjust inode references, so that the
1714 * procfs/diag interfaces really show this one belonging to the correct
1715 * user.
1716 */
1717 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1718 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1719 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1720
1721 subflow = mptcp_subflow_ctx(sf->sk);
1722 pr_debug("subflow=%p", subflow);
1723
1724 *new_sock = sf;
1725 sock_hold(sk);
1726 subflow->conn = sk;
1727 mptcp_subflow_ops_override(sf->sk);
1728
1729 return 0;
1730}
1731
1732static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1733 gfp_t priority)
1734{
1735 struct inet_connection_sock *icsk = inet_csk(sk);
1736 struct mptcp_subflow_context *ctx;
1737
1738 ctx = kzalloc(sizeof(*ctx), priority);
1739 if (!ctx)
1740 return NULL;
1741
1742 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1743 INIT_LIST_HEAD(&ctx->node);
1744 INIT_LIST_HEAD(&ctx->delegated_node);
1745
1746 pr_debug("subflow=%p", ctx);
1747
1748 ctx->tcp_sock = sk;
1749
1750 return ctx;
1751}
1752
1753static void __subflow_state_change(struct sock *sk)
1754{
1755 struct socket_wq *wq;
1756
1757 rcu_read_lock();
1758 wq = rcu_dereference(sk->sk_wq);
1759 if (skwq_has_sleeper(wq))
1760 wake_up_interruptible_all(&wq->wait);
1761 rcu_read_unlock();
1762}
1763
1764static bool subflow_is_done(const struct sock *sk)
1765{
1766 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1767}
1768
1769static void subflow_state_change(struct sock *sk)
1770{
1771 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1772 struct sock *parent = subflow->conn;
1773
1774 __subflow_state_change(sk);
1775
1776 if (subflow_simultaneous_connect(sk)) {
1777 mptcp_propagate_sndbuf(parent, sk);
1778 mptcp_do_fallback(sk);
1779 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1780 pr_fallback(mptcp_sk(parent));
1781 subflow->conn_finished = 1;
1782 mptcp_set_connected(parent);
1783 }
1784
1785 /* as recvmsg() does not acquire the subflow socket for ssk selection
1786 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1787 * the data available machinery here.
1788 */
1789 if (mptcp_subflow_data_available(sk))
1790 mptcp_data_ready(parent, sk);
1791 else if (unlikely(sk->sk_err))
1792 subflow_error_report(sk);
1793
1794 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1795
1796 if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1797 !subflow->rx_eof && subflow_is_done(sk)) {
1798 subflow->rx_eof = 1;
1799 mptcp_subflow_eof(parent);
1800 }
1801}
1802
1803void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1804{
1805 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
1806 struct mptcp_sock *msk, *next, *head = NULL;
1807 struct request_sock *req;
1808
1809 /* build a list of all unaccepted mptcp sockets */
1810 spin_lock_bh(&queue->rskq_lock);
1811 for (req = queue->rskq_accept_head; req; req = req->dl_next) {
1812 struct mptcp_subflow_context *subflow;
1813 struct sock *ssk = req->sk;
1814 struct mptcp_sock *msk;
1815
1816 if (!sk_is_mptcp(ssk))
1817 continue;
1818
1819 subflow = mptcp_subflow_ctx(ssk);
1820 if (!subflow || !subflow->conn)
1821 continue;
1822
1823 /* skip if already in list */
1824 msk = mptcp_sk(subflow->conn);
1825 if (msk->dl_next || msk == head)
1826 continue;
1827
1828 msk->dl_next = head;
1829 head = msk;
1830 }
1831 spin_unlock_bh(&queue->rskq_lock);
1832 if (!head)
1833 return;
1834
1835 /* can't acquire the msk socket lock under the subflow one,
1836 * or will cause ABBA deadlock
1837 */
1838 release_sock(listener_ssk);
1839
1840 for (msk = head; msk; msk = next) {
1841 struct sock *sk = (struct sock *)msk;
1842 bool do_cancel_work;
1843
1844 sock_hold(sk);
1845 lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1846 next = msk->dl_next;
1847 msk->first = NULL;
1848 msk->dl_next = NULL;
1849
1850 do_cancel_work = __mptcp_close(sk, 0);
1851 release_sock(sk);
1852 if (do_cancel_work) {
1853 /* lockdep will report a false positive ABBA deadlock
1854 * between cancel_work_sync and the listener socket.
1855 * The involved locks belong to different sockets WRT
1856 * the existing AB chain.
1857 * Using a per socket key is problematic as key
1858 * deregistration requires process context and must be
1859 * performed at socket disposal time, in atomic
1860 * context.
1861 * Just tell lockdep to consider the listener socket
1862 * released here.
1863 */
1864 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1865 mptcp_cancel_work(sk);
1866 mutex_acquire(&listener_sk->sk_lock.dep_map,
1867 SINGLE_DEPTH_NESTING, 0, _RET_IP_);
1868 }
1869 sock_put(sk);
1870 }
1871
1872 /* we are still under the listener msk socket lock */
1873 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
1874}
1875
1876static int subflow_ulp_init(struct sock *sk)
1877{
1878 struct inet_connection_sock *icsk = inet_csk(sk);
1879 struct mptcp_subflow_context *ctx;
1880 struct tcp_sock *tp = tcp_sk(sk);
1881 int err = 0;
1882
1883 /* disallow attaching ULP to a socket unless it has been
1884 * created with sock_create_kern()
1885 */
1886 if (!sk->sk_kern_sock) {
1887 err = -EOPNOTSUPP;
1888 goto out;
1889 }
1890
1891 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1892 if (!ctx) {
1893 err = -ENOMEM;
1894 goto out;
1895 }
1896
1897 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1898
1899 tp->is_mptcp = 1;
1900 ctx->icsk_af_ops = icsk->icsk_af_ops;
1901 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1902 ctx->tcp_state_change = sk->sk_state_change;
1903 ctx->tcp_error_report = sk->sk_error_report;
1904
1905 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1906 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1907
1908 sk->sk_data_ready = subflow_data_ready;
1909 sk->sk_write_space = subflow_write_space;
1910 sk->sk_state_change = subflow_state_change;
1911 sk->sk_error_report = subflow_error_report;
1912out:
1913 return err;
1914}
1915
1916static void subflow_ulp_release(struct sock *ssk)
1917{
1918 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1919 bool release = true;
1920 struct sock *sk;
1921
1922 if (!ctx)
1923 return;
1924
1925 sk = ctx->conn;
1926 if (sk) {
1927 /* if the msk has been orphaned, keep the ctx
1928 * alive, will be freed by __mptcp_close_ssk(),
1929 * when the subflow is still unaccepted
1930 */
1931 release = ctx->disposable || list_empty(&ctx->node);
1932 sock_put(sk);
1933 }
1934
1935 mptcp_subflow_ops_undo_override(ssk);
1936 if (release)
1937 kfree_rcu(ctx, rcu);
1938}
1939
1940static void subflow_ulp_clone(const struct request_sock *req,
1941 struct sock *newsk,
1942 const gfp_t priority)
1943{
1944 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1945 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1946 struct mptcp_subflow_context *new_ctx;
1947
1948 if (!tcp_rsk(req)->is_mptcp ||
1949 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1950 subflow_ulp_fallback(newsk, old_ctx);
1951 return;
1952 }
1953
1954 new_ctx = subflow_create_ctx(newsk, priority);
1955 if (!new_ctx) {
1956 subflow_ulp_fallback(newsk, old_ctx);
1957 return;
1958 }
1959
1960 new_ctx->conn_finished = 1;
1961 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1962 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1963 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1964 new_ctx->rel_write_seq = 1;
1965 new_ctx->tcp_sock = newsk;
1966
1967 if (subflow_req->mp_capable) {
1968 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1969 * is fully established only after we receive the remote key
1970 */
1971 new_ctx->mp_capable = 1;
1972 new_ctx->local_key = subflow_req->local_key;
1973 new_ctx->token = subflow_req->token;
1974 new_ctx->ssn_offset = subflow_req->ssn_offset;
1975 new_ctx->idsn = subflow_req->idsn;
1976
1977 /* this is the first subflow, id is always 0 */
1978 new_ctx->local_id_valid = 1;
1979 } else if (subflow_req->mp_join) {
1980 new_ctx->ssn_offset = subflow_req->ssn_offset;
1981 new_ctx->mp_join = 1;
1982 new_ctx->fully_established = 1;
1983 new_ctx->remote_key_valid = 1;
1984 new_ctx->backup = subflow_req->backup;
1985 new_ctx->remote_id = subflow_req->remote_id;
1986 new_ctx->token = subflow_req->token;
1987 new_ctx->thmac = subflow_req->thmac;
1988
1989 /* the subflow req id is valid, fetched via subflow_check_req()
1990 * and subflow_token_join_request()
1991 */
1992 subflow_set_local_id(new_ctx, subflow_req->local_id);
1993 }
1994}
1995
1996static void tcp_release_cb_override(struct sock *ssk)
1997{
1998 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1999
2000 if (mptcp_subflow_has_delegated_action(subflow))
2001 mptcp_subflow_process_delegated(ssk);
2002
2003 tcp_release_cb(ssk);
2004}
2005
2006static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
2007 .name = "mptcp",
2008 .owner = THIS_MODULE,
2009 .init = subflow_ulp_init,
2010 .release = subflow_ulp_release,
2011 .clone = subflow_ulp_clone,
2012};
2013
2014static int subflow_ops_init(struct request_sock_ops *subflow_ops)
2015{
2016 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
2017
2018 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
2019 subflow_ops->obj_size, 0,
2020 SLAB_ACCOUNT |
2021 SLAB_TYPESAFE_BY_RCU,
2022 NULL);
2023 if (!subflow_ops->slab)
2024 return -ENOMEM;
2025
2026 return 0;
2027}
2028
2029void __init mptcp_subflow_init(void)
2030{
2031 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
2032 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
2033 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
2034
2035 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
2036 panic("MPTCP: failed to init subflow v4 request sock ops\n");
2037
2038 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
2039 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
2040 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
2041
2042 subflow_specific = ipv4_specific;
2043 subflow_specific.conn_request = subflow_v4_conn_request;
2044 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
2045 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
2046 subflow_specific.rebuild_header = subflow_rebuild_header;
2047
2048 tcp_prot_override = tcp_prot;
2049 tcp_prot_override.release_cb = tcp_release_cb_override;
2050
2051#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2052 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock
2053 * structures for v4 and v6 have the same size. It should not changed in
2054 * the future but better to make sure to be warned if it is no longer
2055 * the case.
2056 */
2057 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
2058
2059 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
2060 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
2061 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
2062
2063 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
2064 panic("MPTCP: failed to init subflow v6 request sock ops\n");
2065
2066 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
2067 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
2068 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
2069
2070 subflow_v6_specific = ipv6_specific;
2071 subflow_v6_specific.conn_request = subflow_v6_conn_request;
2072 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
2073 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
2074 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
2075
2076 subflow_v6m_specific = subflow_v6_specific;
2077 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
2078 subflow_v6m_specific.send_check = ipv4_specific.send_check;
2079 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
2080 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
2081 subflow_v6m_specific.net_frag_header_len = 0;
2082 subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
2083
2084 tcpv6_prot_override = tcpv6_prot;
2085 tcpv6_prot_override.release_cb = tcp_release_cb_override;
2086#endif
2087
2088 mptcp_diag_subflow_init(&subflow_ulp_ops);
2089
2090 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
2091 panic("MPTCP: failed to register subflows to ULP\n");
2092}