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(net: sock_net(sk: 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(rsk: req);
42
43 pr_debug("subflow_req=%p", subflow_req);
44
45 if (subflow_req->msk)
46 sock_put(sk: (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(val: nonce1, p: &msg[0]);
57 put_unaligned_be32(val: nonce2, p: &msg[4]);
58
59 mptcp_crypto_hmac_sha(key1, key2, msg, len: 8, hmac);
60}
61
62static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
63{
64 return mptcp_is_fully_established(sk: (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(buf: &subflow_req->local_nonce, len: sizeof(u32));
77
78 subflow_generate_hmac(key1: msk->local_key, key2: msk->remote_key,
79 nonce1: subflow_req->local_nonce,
80 nonce2: subflow_req->remote_nonce, hmac);
81
82 subflow_req->thmac = get_unaligned_be64(p: 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(rsk: req);
88 struct mptcp_sock *msk;
89 int local_id;
90
91 msk = mptcp_token_get_sock(net: sock_net(sk: req_to_sk(req)), token: subflow_req->token);
92 if (!msk) {
93 SUBFLOW_REQ_INC_STATS(req, field: MPTCP_MIB_JOINNOTOKEN);
94 return NULL;
95 }
96
97 local_id = mptcp_pm_get_local_id(msk, skc: (struct sock_common *)req);
98 if (local_id < 0) {
99 sock_put(sk: (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(rsk: req);
110
111 subflow_req->mp_capable = 0;
112 subflow_req->mp_join = 0;
113 subflow_req->csum_reqd = mptcp_is_checksum_enabled(net: sock_net(sk: sk_listener));
114 subflow_req->allow_join_id0 = mptcp_allow_join_id0(net: sock_net(sk: 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, id: 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: sk_listener);
144 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(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: &mp_opt);
159
160 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
161 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
162 if (opt_mp_capable) {
163 SUBFLOW_REQ_INC_STATS(req, field: MPTCP_MIB_MPCAPABLEPASSIVE);
164
165 if (opt_mp_join)
166 return 0;
167 } else if (opt_mp_join) {
168 SUBFLOW_REQ_INC_STATS(req, field: 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(buf: &subflow_req->local_key, len: sizeof(subflow_req->local_key));
178 } while (subflow_req->local_key == 0);
179
180 if (unlikely(req->syncookie)) {
181 mptcp_crypto_key_sha(key: subflow_req->local_key,
182 token: &subflow_req->token,
183 idsn: &subflow_req->idsn);
184 if (mptcp_token_exists(token: subflow_req->token)) {
185 if (retries-- > 0)
186 goto again;
187 SUBFLOW_REQ_INC_STATS(req, field: 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, field: 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(msk: subflow_req->msk, sk: 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(msk: subflow_req->msk, sk: sk_listener)) {
222 SUBFLOW_REQ_INC_STATS(req, field: MPTCP_MIB_MISMATCHPORTSYNRX);
223 return -EPERM;
224 }
225 SUBFLOW_REQ_INC_STATS(req, field: 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(msk: 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: sk_listener);
249 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(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: &mp_opt);
256
257 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
258 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
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_listener: 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_listener: 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(sk: 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_listener: 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_listener: 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(key1: subflow->remote_key, key2: subflow->local_key,
385 nonce1: subflow->remote_nonce, nonce2: subflow->local_nonce,
386 hmac);
387
388 thmac = get_unaligned_be64(p: 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(sk: 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(sk: ssk, GFP_ATOMIC);
410 tcp_done(sk: ssk);
411 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, addr: &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_set_connected(struct sock *sk)
423{
424 __mptcp_propagate_sndbuf(sk, mptcp_sk(sk)->first);
425 if (sk->sk_state == TCP_SYN_SENT) {
426 inet_sk_state_store(sk, newstate: TCP_ESTABLISHED);
427 sk->sk_state_change(sk);
428 }
429}
430
431static void mptcp_set_connected(struct sock *sk)
432{
433 mptcp_data_lock(sk);
434 if (!sock_owned_by_user(sk))
435 __mptcp_set_connected(sk);
436 else
437 __set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->cb_flags);
438 mptcp_data_unlock(sk);
439}
440
441static void subflow_set_remote_key(struct mptcp_sock *msk,
442 struct mptcp_subflow_context *subflow,
443 const struct mptcp_options_received *mp_opt)
444{
445 /* active MPC subflow will reach here multiple times:
446 * at subflow_finish_connect() time and at 4th ack time
447 */
448 if (subflow->remote_key_valid)
449 return;
450
451 subflow->remote_key_valid = 1;
452 subflow->remote_key = mp_opt->sndr_key;
453 mptcp_crypto_key_sha(key: subflow->remote_key, NULL, idsn: &subflow->iasn);
454 subflow->iasn++;
455
456 WRITE_ONCE(msk->remote_key, subflow->remote_key);
457 WRITE_ONCE(msk->ack_seq, subflow->iasn);
458 WRITE_ONCE(msk->can_ack, true);
459 atomic64_set(v: &msk->rcv_wnd_sent, i: subflow->iasn);
460}
461
462static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
463{
464 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
465 struct mptcp_options_received mp_opt;
466 struct sock *parent = subflow->conn;
467 struct mptcp_sock *msk;
468
469 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
470
471 /* be sure no special action on any packet other than syn-ack */
472 if (subflow->conn_finished)
473 return;
474
475 msk = mptcp_sk(parent);
476 subflow->rel_write_seq = 1;
477 subflow->conn_finished = 1;
478 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
479 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
480
481 mptcp_get_options(skb, mp_opt: &mp_opt);
482 if (subflow->request_mptcp) {
483 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
484 MPTCP_INC_STATS(net: sock_net(sk),
485 field: MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
486 mptcp_do_fallback(ssk: sk);
487 pr_fallback(msk);
488 goto fallback;
489 }
490
491 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
492 WRITE_ONCE(msk->csum_enabled, true);
493 if (mp_opt.deny_join_id0)
494 WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
495 subflow->mp_capable = 1;
496 subflow_set_remote_key(msk, subflow, mp_opt: &mp_opt);
497 MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_MPCAPABLEACTIVEACK);
498 mptcp_finish_connect(sk);
499 mptcp_set_connected(sk: parent);
500 } else if (subflow->request_join) {
501 u8 hmac[SHA256_DIGEST_SIZE];
502
503 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) {
504 subflow->reset_reason = MPTCP_RST_EMPTCP;
505 goto do_reset;
506 }
507
508 subflow->backup = mp_opt.backup;
509 subflow->thmac = mp_opt.thmac;
510 subflow->remote_nonce = mp_opt.nonce;
511 subflow->remote_id = mp_opt.join_id;
512 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
513 subflow, subflow->thmac, subflow->remote_nonce,
514 subflow->backup);
515
516 if (!subflow_thmac_valid(subflow)) {
517 MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_JOINACKMAC);
518 subflow->reset_reason = MPTCP_RST_EMPTCP;
519 goto do_reset;
520 }
521
522 if (!mptcp_finish_join(sk))
523 goto do_reset;
524
525 subflow_generate_hmac(key1: subflow->local_key, key2: subflow->remote_key,
526 nonce1: subflow->local_nonce,
527 nonce2: subflow->remote_nonce,
528 hmac);
529 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
530
531 subflow->mp_join = 1;
532 MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_JOINSYNACKRX);
533
534 if (subflow_use_different_dport(msk, sk)) {
535 pr_debug("synack inet_dport=%d %d",
536 ntohs(inet_sk(sk)->inet_dport),
537 ntohs(inet_sk(parent)->inet_dport));
538 MPTCP_INC_STATS(net: sock_net(sk), field: MPTCP_MIB_JOINPORTSYNACKRX);
539 }
540 } else if (mptcp_check_fallback(sk)) {
541fallback:
542 mptcp_rcv_space_init(msk, ssk: sk);
543 mptcp_set_connected(sk: parent);
544 }
545 return;
546
547do_reset:
548 subflow->reset_transient = 0;
549 mptcp_subflow_reset(ssk: sk);
550}
551
552static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
553{
554 subflow->local_id = local_id;
555 subflow->local_id_valid = 1;
556}
557
558static int subflow_chk_local_id(struct sock *sk)
559{
560 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
561 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
562 int err;
563
564 if (likely(subflow->local_id_valid))
565 return 0;
566
567 err = mptcp_pm_get_local_id(msk, skc: (struct sock_common *)sk);
568 if (err < 0)
569 return err;
570
571 subflow_set_local_id(subflow, local_id: err);
572 return 0;
573}
574
575static int subflow_rebuild_header(struct sock *sk)
576{
577 int err = subflow_chk_local_id(sk);
578
579 if (unlikely(err < 0))
580 return err;
581
582 return inet_sk_rebuild_header(sk);
583}
584
585#if IS_ENABLED(CONFIG_MPTCP_IPV6)
586static int subflow_v6_rebuild_header(struct sock *sk)
587{
588 int err = subflow_chk_local_id(sk);
589
590 if (unlikely(err < 0))
591 return err;
592
593 return inet6_sk_rebuild_header(sk);
594}
595#endif
596
597static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
598static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
599
600static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
601{
602 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
603
604 pr_debug("subflow=%p", subflow);
605
606 /* Never answer to SYNs sent to broadcast or multicast */
607 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
608 goto drop;
609
610 return tcp_conn_request(rsk_ops: &mptcp_subflow_v4_request_sock_ops,
611 af_ops: &subflow_request_sock_ipv4_ops,
612 sk, skb);
613drop:
614 tcp_listendrop(sk);
615 return 0;
616}
617
618static void subflow_v4_req_destructor(struct request_sock *req)
619{
620 subflow_req_destructor(req);
621 tcp_request_sock_ops.destructor(req);
622}
623
624#if IS_ENABLED(CONFIG_MPTCP_IPV6)
625static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
626static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
627static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
628static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
629static struct proto tcpv6_prot_override __ro_after_init;
630
631static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
632{
633 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
634
635 pr_debug("subflow=%p", subflow);
636
637 if (skb->protocol == htons(ETH_P_IP))
638 return subflow_v4_conn_request(sk, skb);
639
640 if (!ipv6_unicast_destination(skb))
641 goto drop;
642
643 if (ipv6_addr_v4mapped(a: &ipv6_hdr(skb)->saddr)) {
644 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
645 return 0;
646 }
647
648 return tcp_conn_request(rsk_ops: &mptcp_subflow_v6_request_sock_ops,
649 af_ops: &subflow_request_sock_ipv6_ops, sk, skb);
650
651drop:
652 tcp_listendrop(sk);
653 return 0; /* don't send reset */
654}
655
656static void subflow_v6_req_destructor(struct request_sock *req)
657{
658 subflow_req_destructor(req);
659 tcp6_request_sock_ops.destructor(req);
660}
661#endif
662
663struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
664 struct sock *sk_listener,
665 bool attach_listener)
666{
667 if (ops->family == AF_INET)
668 ops = &mptcp_subflow_v4_request_sock_ops;
669#if IS_ENABLED(CONFIG_MPTCP_IPV6)
670 else if (ops->family == AF_INET6)
671 ops = &mptcp_subflow_v6_request_sock_ops;
672#endif
673
674 return inet_reqsk_alloc(ops, sk_listener, attach_listener);
675}
676EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
677
678/* validate hmac received in third ACK */
679static bool subflow_hmac_valid(const struct request_sock *req,
680 const struct mptcp_options_received *mp_opt)
681{
682 const struct mptcp_subflow_request_sock *subflow_req;
683 u8 hmac[SHA256_DIGEST_SIZE];
684 struct mptcp_sock *msk;
685
686 subflow_req = mptcp_subflow_rsk(rsk: req);
687 msk = subflow_req->msk;
688 if (!msk)
689 return false;
690
691 subflow_generate_hmac(key1: msk->remote_key, key2: msk->local_key,
692 nonce1: subflow_req->remote_nonce,
693 nonce2: subflow_req->local_nonce, hmac);
694
695 return !crypto_memneq(a: hmac, b: mp_opt->hmac, MPTCPOPT_HMAC_LEN);
696}
697
698static void subflow_ulp_fallback(struct sock *sk,
699 struct mptcp_subflow_context *old_ctx)
700{
701 struct inet_connection_sock *icsk = inet_csk(sk);
702
703 mptcp_subflow_tcp_fallback(sk, ctx: old_ctx);
704 icsk->icsk_ulp_ops = NULL;
705 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
706 tcp_sk(sk)->is_mptcp = 0;
707
708 mptcp_subflow_ops_undo_override(ssk: sk);
709}
710
711void mptcp_subflow_drop_ctx(struct sock *ssk)
712{
713 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(sk: ssk);
714
715 if (!ctx)
716 return;
717
718 list_del(entry: &mptcp_subflow_ctx(sk: ssk)->node);
719 if (inet_csk(sk: ssk)->icsk_ulp_ops) {
720 subflow_ulp_fallback(sk: ssk, old_ctx: ctx);
721 if (ctx->conn)
722 sock_put(sk: ctx->conn);
723 }
724
725 kfree_rcu(ctx, rcu);
726}
727
728void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
729 const struct mptcp_options_received *mp_opt)
730{
731 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
732
733 subflow_set_remote_key(msk, subflow, mp_opt);
734 subflow->fully_established = 1;
735 WRITE_ONCE(msk->fully_established, true);
736
737 if (subflow->is_mptfo)
738 mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt);
739}
740
741static struct sock *subflow_syn_recv_sock(const struct sock *sk,
742 struct sk_buff *skb,
743 struct request_sock *req,
744 struct dst_entry *dst,
745 struct request_sock *req_unhash,
746 bool *own_req)
747{
748 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
749 struct mptcp_subflow_request_sock *subflow_req;
750 struct mptcp_options_received mp_opt;
751 bool fallback, fallback_is_fatal;
752 struct mptcp_sock *owner;
753 struct sock *child;
754
755 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
756
757 /* After child creation we must look for MPC even when options
758 * are not parsed
759 */
760 mp_opt.suboptions = 0;
761
762 /* hopefully temporary handling for MP_JOIN+syncookie */
763 subflow_req = mptcp_subflow_rsk(rsk: req);
764 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
765 fallback = !tcp_rsk(req)->is_mptcp;
766 if (fallback)
767 goto create_child;
768
769 /* if the sk is MP_CAPABLE, we try to fetch the client key */
770 if (subflow_req->mp_capable) {
771 /* we can receive and accept an in-window, out-of-order pkt,
772 * which may not carry the MP_CAPABLE opt even on mptcp enabled
773 * paths: always try to extract the peer key, and fallback
774 * for packets missing it.
775 * Even OoO DSS packets coming legitly after dropped or
776 * reordered MPC will cause fallback, but we don't have other
777 * options.
778 */
779 mptcp_get_options(skb, mp_opt: &mp_opt);
780 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC))
781 fallback = true;
782
783 } else if (subflow_req->mp_join) {
784 mptcp_get_options(skb, mp_opt: &mp_opt);
785 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||
786 !subflow_hmac_valid(req, mp_opt: &mp_opt) ||
787 !mptcp_can_accept_new_subflow(msk: subflow_req->msk)) {
788 SUBFLOW_REQ_INC_STATS(req, field: MPTCP_MIB_JOINACKMAC);
789 fallback = true;
790 }
791 }
792
793create_child:
794 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
795 req_unhash, own_req);
796
797 if (child && *own_req) {
798 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(sk: child);
799
800 tcp_rsk(req)->drop_req = false;
801
802 /* we need to fallback on ctx allocation failure and on pre-reqs
803 * checking above. In the latter scenario we additionally need
804 * to reset the context to non MPTCP status.
805 */
806 if (!ctx || fallback) {
807 if (fallback_is_fatal) {
808 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
809 goto dispose_child;
810 }
811 goto fallback;
812 }
813
814 /* ssk inherits options of listener sk */
815 ctx->setsockopt_seq = listener->setsockopt_seq;
816
817 if (ctx->mp_capable) {
818 ctx->conn = mptcp_sk_clone_init(sk: listener->conn, mp_opt: &mp_opt, ssk: child, req);
819 if (!ctx->conn)
820 goto fallback;
821
822 ctx->subflow_id = 1;
823 owner = mptcp_sk(ctx->conn);
824 mptcp_pm_new_connection(msk: owner, ssk: child, server_side: 1);
825
826 /* with OoO packets we can reach here without ingress
827 * mpc option
828 */
829 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) {
830 mptcp_subflow_fully_established(subflow: ctx, mp_opt: &mp_opt);
831 mptcp_pm_fully_established(msk: owner, ssk: child);
832 ctx->pm_notified = 1;
833 }
834 } else if (ctx->mp_join) {
835 owner = subflow_req->msk;
836 if (!owner) {
837 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
838 goto dispose_child;
839 }
840
841 /* move the msk reference ownership to the subflow */
842 subflow_req->msk = NULL;
843 ctx->conn = (struct sock *)owner;
844
845 if (subflow_use_different_sport(msk: owner, sk)) {
846 pr_debug("ack inet_sport=%d %d",
847 ntohs(inet_sk(sk)->inet_sport),
848 ntohs(inet_sk((struct sock *)owner)->inet_sport));
849 if (!mptcp_pm_sport_in_anno_list(msk: owner, sk)) {
850 SUBFLOW_REQ_INC_STATS(req, field: MPTCP_MIB_MISMATCHPORTACKRX);
851 goto dispose_child;
852 }
853 SUBFLOW_REQ_INC_STATS(req, field: MPTCP_MIB_JOINPORTACKRX);
854 }
855
856 if (!mptcp_finish_join(sk: child))
857 goto dispose_child;
858
859 SUBFLOW_REQ_INC_STATS(req, field: MPTCP_MIB_JOINACKRX);
860 tcp_rsk(req)->drop_req = true;
861 }
862 }
863
864 /* check for expected invariant - should never trigger, just help
865 * catching eariler subtle bugs
866 */
867 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
868 (!mptcp_subflow_ctx(child) ||
869 !mptcp_subflow_ctx(child)->conn));
870 return child;
871
872dispose_child:
873 mptcp_subflow_drop_ctx(ssk: child);
874 tcp_rsk(req)->drop_req = true;
875 inet_csk_prepare_for_destroy_sock(sk: child);
876 tcp_done(sk: child);
877 req->rsk_ops->send_reset(sk, skb);
878
879 /* The last child reference will be released by the caller */
880 return child;
881
882fallback:
883 mptcp_subflow_drop_ctx(ssk: child);
884 return child;
885}
886
887static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
888static struct proto tcp_prot_override __ro_after_init;
889
890enum mapping_status {
891 MAPPING_OK,
892 MAPPING_INVALID,
893 MAPPING_EMPTY,
894 MAPPING_DATA_FIN,
895 MAPPING_DUMMY,
896 MAPPING_BAD_CSUM
897};
898
899static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
900{
901 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
902 ssn, subflow->map_subflow_seq, subflow->map_data_len);
903}
904
905static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
906{
907 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
908 unsigned int skb_consumed;
909
910 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
911 if (WARN_ON_ONCE(skb_consumed >= skb->len))
912 return true;
913
914 return skb->len - skb_consumed <= subflow->map_data_len -
915 mptcp_subflow_get_map_offset(subflow);
916}
917
918static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
919{
920 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
921 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
922
923 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
924 /* Mapping covers data later in the subflow stream,
925 * currently unsupported.
926 */
927 dbg_bad_map(subflow, ssn);
928 return false;
929 }
930 if (unlikely(!before(ssn, subflow->map_subflow_seq +
931 subflow->map_data_len))) {
932 /* Mapping does covers past subflow data, invalid */
933 dbg_bad_map(subflow, ssn);
934 return false;
935 }
936 return true;
937}
938
939static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
940 bool csum_reqd)
941{
942 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
943 u32 offset, seq, delta;
944 __sum16 csum;
945 int len;
946
947 if (!csum_reqd)
948 return MAPPING_OK;
949
950 /* mapping already validated on previous traversal */
951 if (subflow->map_csum_len == subflow->map_data_len)
952 return MAPPING_OK;
953
954 /* traverse the receive queue, ensuring it contains a full
955 * DSS mapping and accumulating the related csum.
956 * Preserve the accoumlate csum across multiple calls, to compute
957 * the csum only once
958 */
959 delta = subflow->map_data_len - subflow->map_csum_len;
960 for (;;) {
961 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
962 offset = seq - TCP_SKB_CB(skb)->seq;
963
964 /* if the current skb has not been accounted yet, csum its contents
965 * up to the amount covered by the current DSS
966 */
967 if (offset < skb->len) {
968 __wsum csum;
969
970 len = min(skb->len - offset, delta);
971 csum = skb_checksum(skb, offset, len, csum: 0);
972 subflow->map_data_csum = csum_block_add(csum: subflow->map_data_csum, csum2: csum,
973 offset: subflow->map_csum_len);
974
975 delta -= len;
976 subflow->map_csum_len += len;
977 }
978 if (delta == 0)
979 break;
980
981 if (skb_queue_is_last(list: &ssk->sk_receive_queue, skb)) {
982 /* if this subflow is closed, the partial mapping
983 * will be never completed; flush the pending skbs, so
984 * that subflow_sched_work_if_closed() can kick in
985 */
986 if (unlikely(ssk->sk_state == TCP_CLOSE))
987 while ((skb = skb_peek(list_: &ssk->sk_receive_queue)))
988 sk_eat_skb(sk: ssk, skb);
989
990 /* not enough data to validate the csum */
991 return MAPPING_EMPTY;
992 }
993
994 /* the DSS mapping for next skbs will be validated later,
995 * when a get_mapping_status call will process such skb
996 */
997 skb = skb->next;
998 }
999
1000 /* note that 'map_data_len' accounts only for the carried data, does
1001 * not include the eventual seq increment due to the data fin,
1002 * while the pseudo header requires the original DSS data len,
1003 * including that
1004 */
1005 csum = __mptcp_make_csum(data_seq: subflow->map_seq,
1006 subflow_seq: subflow->map_subflow_seq,
1007 data_len: subflow->map_data_len + subflow->map_data_fin,
1008 sum: subflow->map_data_csum);
1009 if (unlikely(csum)) {
1010 MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_DATACSUMERR);
1011 return MAPPING_BAD_CSUM;
1012 }
1013
1014 subflow->valid_csum_seen = 1;
1015 return MAPPING_OK;
1016}
1017
1018static enum mapping_status get_mapping_status(struct sock *ssk,
1019 struct mptcp_sock *msk)
1020{
1021 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
1022 bool csum_reqd = READ_ONCE(msk->csum_enabled);
1023 struct mptcp_ext *mpext;
1024 struct sk_buff *skb;
1025 u16 data_len;
1026 u64 map_seq;
1027
1028 skb = skb_peek(list_: &ssk->sk_receive_queue);
1029 if (!skb)
1030 return MAPPING_EMPTY;
1031
1032 if (mptcp_check_fallback(sk: ssk))
1033 return MAPPING_DUMMY;
1034
1035 mpext = mptcp_get_ext(skb);
1036 if (!mpext || !mpext->use_map) {
1037 if (!subflow->map_valid && !skb->len) {
1038 /* the TCP stack deliver 0 len FIN pkt to the receive
1039 * queue, that is the only 0len pkts ever expected here,
1040 * and we can admit no mapping only for 0 len pkts
1041 */
1042 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
1043 WARN_ONCE(1, "0len seq %d:%d flags %x",
1044 TCP_SKB_CB(skb)->seq,
1045 TCP_SKB_CB(skb)->end_seq,
1046 TCP_SKB_CB(skb)->tcp_flags);
1047 sk_eat_skb(sk: ssk, skb);
1048 return MAPPING_EMPTY;
1049 }
1050
1051 if (!subflow->map_valid)
1052 return MAPPING_INVALID;
1053
1054 goto validate_seq;
1055 }
1056
1057 trace_get_mapping_status(mpext);
1058
1059 data_len = mpext->data_len;
1060 if (data_len == 0) {
1061 pr_debug("infinite mapping received");
1062 MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_INFINITEMAPRX);
1063 subflow->map_data_len = 0;
1064 return MAPPING_INVALID;
1065 }
1066
1067 if (mpext->data_fin == 1) {
1068 if (data_len == 1) {
1069 bool updated = mptcp_update_rcv_data_fin(msk, data_fin_seq: mpext->data_seq,
1070 use_64bit: mpext->dsn64);
1071 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
1072 if (subflow->map_valid) {
1073 /* A DATA_FIN might arrive in a DSS
1074 * option before the previous mapping
1075 * has been fully consumed. Continue
1076 * handling the existing mapping.
1077 */
1078 skb_ext_del(skb, id: SKB_EXT_MPTCP);
1079 return MAPPING_OK;
1080 } else {
1081 if (updated)
1082 mptcp_schedule_work(sk: (struct sock *)msk);
1083
1084 return MAPPING_DATA_FIN;
1085 }
1086 } else {
1087 u64 data_fin_seq = mpext->data_seq + data_len - 1;
1088
1089 /* If mpext->data_seq is a 32-bit value, data_fin_seq
1090 * must also be limited to 32 bits.
1091 */
1092 if (!mpext->dsn64)
1093 data_fin_seq &= GENMASK_ULL(31, 0);
1094
1095 mptcp_update_rcv_data_fin(msk, data_fin_seq, use_64bit: mpext->dsn64);
1096 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
1097 data_fin_seq, mpext->dsn64);
1098 }
1099
1100 /* Adjust for DATA_FIN using 1 byte of sequence space */
1101 data_len--;
1102 }
1103
1104 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), cur_seq: mpext->data_seq, use_64bit: mpext->dsn64);
1105 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1106
1107 if (subflow->map_valid) {
1108 /* Allow replacing only with an identical map */
1109 if (subflow->map_seq == map_seq &&
1110 subflow->map_subflow_seq == mpext->subflow_seq &&
1111 subflow->map_data_len == data_len &&
1112 subflow->map_csum_reqd == mpext->csum_reqd) {
1113 skb_ext_del(skb, id: SKB_EXT_MPTCP);
1114 goto validate_csum;
1115 }
1116
1117 /* If this skb data are fully covered by the current mapping,
1118 * the new map would need caching, which is not supported
1119 */
1120 if (skb_is_fully_mapped(ssk, skb)) {
1121 MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_DSSNOMATCH);
1122 return MAPPING_INVALID;
1123 }
1124
1125 /* will validate the next map after consuming the current one */
1126 goto validate_csum;
1127 }
1128
1129 subflow->map_seq = map_seq;
1130 subflow->map_subflow_seq = mpext->subflow_seq;
1131 subflow->map_data_len = data_len;
1132 subflow->map_valid = 1;
1133 subflow->map_data_fin = mpext->data_fin;
1134 subflow->mpc_map = mpext->mpc_map;
1135 subflow->map_csum_reqd = mpext->csum_reqd;
1136 subflow->map_csum_len = 0;
1137 subflow->map_data_csum = csum_unfold(n: mpext->csum);
1138
1139 /* Cfr RFC 8684 Section 3.3.0 */
1140 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1141 return MAPPING_INVALID;
1142
1143 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1144 subflow->map_seq, subflow->map_subflow_seq,
1145 subflow->map_data_len, subflow->map_csum_reqd,
1146 subflow->map_data_csum);
1147
1148validate_seq:
1149 /* we revalidate valid mapping on new skb, because we must ensure
1150 * the current skb is completely covered by the available mapping
1151 */
1152 if (!validate_mapping(ssk, skb)) {
1153 MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_DSSTCPMISMATCH);
1154 return MAPPING_INVALID;
1155 }
1156
1157 skb_ext_del(skb, id: SKB_EXT_MPTCP);
1158
1159validate_csum:
1160 return validate_data_csum(ssk, skb, csum_reqd);
1161}
1162
1163static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1164 u64 limit)
1165{
1166 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
1167 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1168 u32 incr;
1169
1170 incr = limit >= skb->len ? skb->len + fin : limit;
1171
1172 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1173 subflow->map_subflow_seq);
1174 MPTCP_INC_STATS(net: sock_net(sk: ssk), field: MPTCP_MIB_DUPDATA);
1175 tcp_sk(ssk)->copied_seq += incr;
1176 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1177 sk_eat_skb(sk: ssk, skb);
1178 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1179 subflow->map_valid = 0;
1180}
1181
1182/* sched mptcp worker to remove the subflow if no more data is pending */
1183static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1184{
1185 if (likely(ssk->sk_state != TCP_CLOSE))
1186 return;
1187
1188 if (skb_queue_empty(list: &ssk->sk_receive_queue) &&
1189 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, addr: &msk->flags))
1190 mptcp_schedule_work(sk: (struct sock *)msk);
1191}
1192
1193static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
1194{
1195 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1196
1197 if (subflow->mp_join)
1198 return false;
1199 else if (READ_ONCE(msk->csum_enabled))
1200 return !subflow->valid_csum_seen;
1201 else
1202 return !subflow->fully_established;
1203}
1204
1205static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1206{
1207 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
1208 unsigned long fail_tout;
1209
1210 /* greceful failure can happen only on the MPC subflow */
1211 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1212 return;
1213
1214 /* since the close timeout take precedence on the fail one,
1215 * no need to start the latter when the first is already set
1216 */
1217 if (sock_flag(sk: (struct sock *)msk, flag: SOCK_DEAD))
1218 return;
1219
1220 /* we don't need extreme accuracy here, use a zero fail_tout as special
1221 * value meaning no fail timeout at all;
1222 */
1223 fail_tout = jiffies + TCP_RTO_MAX;
1224 if (!fail_tout)
1225 fail_tout = 1;
1226 WRITE_ONCE(subflow->fail_tout, fail_tout);
1227 tcp_send_ack(sk: ssk);
1228
1229 mptcp_reset_tout_timer(msk, fail_tout: subflow->fail_tout);
1230}
1231
1232static bool subflow_check_data_avail(struct sock *ssk)
1233{
1234 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
1235 enum mapping_status status;
1236 struct mptcp_sock *msk;
1237 struct sk_buff *skb;
1238
1239 if (!skb_peek(list_: &ssk->sk_receive_queue))
1240 WRITE_ONCE(subflow->data_avail, false);
1241 if (subflow->data_avail)
1242 return true;
1243
1244 msk = mptcp_sk(subflow->conn);
1245 for (;;) {
1246 u64 ack_seq;
1247 u64 old_ack;
1248
1249 status = get_mapping_status(ssk, msk);
1250 trace_subflow_check_data_avail(status, skb: skb_peek(list_: &ssk->sk_receive_queue));
1251 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1252 status == MAPPING_BAD_CSUM))
1253 goto fallback;
1254
1255 if (status != MAPPING_OK)
1256 goto no_data;
1257
1258 skb = skb_peek(list_: &ssk->sk_receive_queue);
1259 if (WARN_ON_ONCE(!skb))
1260 goto no_data;
1261
1262 if (unlikely(!READ_ONCE(msk->can_ack)))
1263 goto fallback;
1264
1265 old_ack = READ_ONCE(msk->ack_seq);
1266 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1267 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1268 ack_seq);
1269 if (unlikely(before64(ack_seq, old_ack))) {
1270 mptcp_subflow_discard_data(ssk, skb, limit: old_ack - ack_seq);
1271 continue;
1272 }
1273
1274 WRITE_ONCE(subflow->data_avail, true);
1275 break;
1276 }
1277 return true;
1278
1279no_data:
1280 subflow_sched_work_if_closed(msk, ssk);
1281 return false;
1282
1283fallback:
1284 if (!__mptcp_check_fallback(msk)) {
1285 /* RFC 8684 section 3.7. */
1286 if (status == MAPPING_BAD_CSUM &&
1287 (subflow->mp_join || subflow->valid_csum_seen)) {
1288 subflow->send_mp_fail = 1;
1289
1290 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1291 subflow->reset_transient = 0;
1292 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1293 goto reset;
1294 }
1295 mptcp_subflow_fail(msk, ssk);
1296 WRITE_ONCE(subflow->data_avail, true);
1297 return true;
1298 }
1299
1300 if (!subflow_can_fallback(subflow) && subflow->map_data_len) {
1301 /* fatal protocol error, close the socket.
1302 * subflow_error_report() will introduce the appropriate barriers
1303 */
1304 subflow->reset_transient = 0;
1305 subflow->reset_reason = MPTCP_RST_EMPTCP;
1306
1307reset:
1308 WRITE_ONCE(ssk->sk_err, EBADMSG);
1309 tcp_set_state(sk: ssk, state: TCP_CLOSE);
1310 while ((skb = skb_peek(list_: &ssk->sk_receive_queue)))
1311 sk_eat_skb(sk: ssk, skb);
1312 tcp_send_active_reset(sk: ssk, GFP_ATOMIC);
1313 WRITE_ONCE(subflow->data_avail, false);
1314 return false;
1315 }
1316
1317 mptcp_do_fallback(ssk);
1318 }
1319
1320 skb = skb_peek(list_: &ssk->sk_receive_queue);
1321 subflow->map_valid = 1;
1322 subflow->map_seq = READ_ONCE(msk->ack_seq);
1323 subflow->map_data_len = skb->len;
1324 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1325 WRITE_ONCE(subflow->data_avail, true);
1326 return true;
1327}
1328
1329bool mptcp_subflow_data_available(struct sock *sk)
1330{
1331 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1332
1333 /* check if current mapping is still valid */
1334 if (subflow->map_valid &&
1335 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1336 subflow->map_valid = 0;
1337 WRITE_ONCE(subflow->data_avail, false);
1338
1339 pr_debug("Done with mapping: seq=%u data_len=%u",
1340 subflow->map_subflow_seq,
1341 subflow->map_data_len);
1342 }
1343
1344 return subflow_check_data_avail(ssk: sk);
1345}
1346
1347/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1348 * not the ssk one.
1349 *
1350 * In mptcp, rwin is about the mptcp-level connection data.
1351 *
1352 * Data that is still on the ssk rx queue can thus be ignored,
1353 * as far as mptcp peer is concerned that data is still inflight.
1354 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1355 */
1356void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1357{
1358 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
1359 const struct sock *sk = subflow->conn;
1360
1361 *space = __mptcp_space(sk);
1362 *full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1363}
1364
1365static void subflow_error_report(struct sock *ssk)
1366{
1367 struct sock *sk = mptcp_subflow_ctx(sk: ssk)->conn;
1368
1369 /* bail early if this is a no-op, so that we avoid introducing a
1370 * problematic lockdep dependency between TCP accept queue lock
1371 * and msk socket spinlock
1372 */
1373 if (!sk->sk_socket)
1374 return;
1375
1376 mptcp_data_lock(sk);
1377 if (!sock_owned_by_user(sk))
1378 __mptcp_error_report(sk);
1379 else
1380 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
1381 mptcp_data_unlock(sk);
1382}
1383
1384static void subflow_data_ready(struct sock *sk)
1385{
1386 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1387 u16 state = 1 << inet_sk_state_load(sk);
1388 struct sock *parent = subflow->conn;
1389 struct mptcp_sock *msk;
1390
1391 trace_sk_data_ready(sk);
1392
1393 msk = mptcp_sk(parent);
1394 if (state & TCPF_LISTEN) {
1395 /* MPJ subflow are removed from accept queue before reaching here,
1396 * avoid stray wakeups
1397 */
1398 if (reqsk_queue_empty(queue: &inet_csk(sk)->icsk_accept_queue))
1399 return;
1400
1401 parent->sk_data_ready(parent);
1402 return;
1403 }
1404
1405 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1406 !subflow->mp_join && !(state & TCPF_CLOSE));
1407
1408 if (mptcp_subflow_data_available(sk)) {
1409 mptcp_data_ready(sk: parent, ssk: sk);
1410
1411 /* subflow-level lowat test are not relevant.
1412 * respect the msk-level threshold eventually mandating an immediate ack
1413 */
1414 if (mptcp_data_avail(msk) < parent->sk_rcvlowat &&
1415 (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss)
1416 inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
1417 } else if (unlikely(sk->sk_err)) {
1418 subflow_error_report(ssk: sk);
1419 }
1420}
1421
1422static void subflow_write_space(struct sock *ssk)
1423{
1424 struct sock *sk = mptcp_subflow_ctx(sk: ssk)->conn;
1425
1426 mptcp_propagate_sndbuf(sk, ssk);
1427 mptcp_write_space(sk);
1428}
1429
1430static const struct inet_connection_sock_af_ops *
1431subflow_default_af_ops(struct sock *sk)
1432{
1433#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1434 if (sk->sk_family == AF_INET6)
1435 return &subflow_v6_specific;
1436#endif
1437 return &subflow_specific;
1438}
1439
1440#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1441void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1442{
1443 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1444 struct inet_connection_sock *icsk = inet_csk(sk);
1445 const struct inet_connection_sock_af_ops *target;
1446
1447 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1448
1449 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1450 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1451
1452 if (likely(icsk->icsk_af_ops == target))
1453 return;
1454
1455 subflow->icsk_af_ops = icsk->icsk_af_ops;
1456 icsk->icsk_af_ops = target;
1457}
1458#endif
1459
1460void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1461 struct sockaddr_storage *addr,
1462 unsigned short family)
1463{
1464 memset(addr, 0, sizeof(*addr));
1465 addr->ss_family = family;
1466 if (addr->ss_family == AF_INET) {
1467 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1468
1469 if (info->family == AF_INET)
1470 in_addr->sin_addr = info->addr;
1471#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1472 else if (ipv6_addr_v4mapped(a: &info->addr6))
1473 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1474#endif
1475 in_addr->sin_port = info->port;
1476 }
1477#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1478 else if (addr->ss_family == AF_INET6) {
1479 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1480
1481 if (info->family == AF_INET)
1482 ipv6_addr_set_v4mapped(addr: info->addr.s_addr,
1483 v4mapped: &in6_addr->sin6_addr);
1484 else
1485 in6_addr->sin6_addr = info->addr6;
1486 in6_addr->sin6_port = info->port;
1487 }
1488#endif
1489}
1490
1491int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1492 const struct mptcp_addr_info *remote)
1493{
1494 struct mptcp_sock *msk = mptcp_sk(sk);
1495 struct mptcp_subflow_context *subflow;
1496 struct sockaddr_storage addr;
1497 int remote_id = remote->id;
1498 int local_id = loc->id;
1499 int err = -ENOTCONN;
1500 struct socket *sf;
1501 struct sock *ssk;
1502 u32 remote_token;
1503 int addrlen;
1504 int ifindex;
1505 u8 flags;
1506
1507 if (!mptcp_is_fully_established(sk))
1508 goto err_out;
1509
1510 err = mptcp_subflow_create_socket(sk, family: loc->family, new_sock: &sf);
1511 if (err)
1512 goto err_out;
1513
1514 ssk = sf->sk;
1515 subflow = mptcp_subflow_ctx(sk: ssk);
1516 do {
1517 get_random_bytes(buf: &subflow->local_nonce, len: sizeof(u32));
1518 } while (!subflow->local_nonce);
1519
1520 if (local_id)
1521 subflow_set_local_id(subflow, local_id);
1522
1523 mptcp_pm_get_flags_and_ifindex_by_id(msk, id: local_id,
1524 flags: &flags, ifindex: &ifindex);
1525 subflow->remote_key_valid = 1;
1526 subflow->remote_key = msk->remote_key;
1527 subflow->local_key = msk->local_key;
1528 subflow->token = msk->token;
1529 mptcp_info2sockaddr(info: loc, addr: &addr, family: ssk->sk_family);
1530
1531 addrlen = sizeof(struct sockaddr_in);
1532#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1533 if (addr.ss_family == AF_INET6)
1534 addrlen = sizeof(struct sockaddr_in6);
1535#endif
1536 ssk->sk_bound_dev_if = ifindex;
1537 err = kernel_bind(sock: sf, addr: (struct sockaddr *)&addr, addrlen);
1538 if (err)
1539 goto failed;
1540
1541 mptcp_crypto_key_sha(key: subflow->remote_key, token: &remote_token, NULL);
1542 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1543 remote_token, local_id, remote_id);
1544 subflow->remote_token = remote_token;
1545 subflow->remote_id = remote_id;
1546 subflow->request_join = 1;
1547 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1548 subflow->subflow_id = msk->subflow_id++;
1549 mptcp_info2sockaddr(info: remote, addr: &addr, family: ssk->sk_family);
1550
1551 sock_hold(sk: ssk);
1552 list_add_tail(new: &subflow->node, head: &msk->conn_list);
1553 err = kernel_connect(sock: sf, addr: (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1554 if (err && err != -EINPROGRESS)
1555 goto failed_unlink;
1556
1557 /* discard the subflow socket */
1558 mptcp_sock_graft(sk: ssk, parent: sk->sk_socket);
1559 iput(SOCK_INODE(socket: sf));
1560 WRITE_ONCE(msk->allow_infinite_fallback, false);
1561 mptcp_stop_tout_timer(sk);
1562 return 0;
1563
1564failed_unlink:
1565 list_del(entry: &subflow->node);
1566 sock_put(sk: mptcp_subflow_tcp_sock(subflow));
1567
1568failed:
1569 subflow->disposable = 1;
1570 sock_release(sock: sf);
1571
1572err_out:
1573 /* we account subflows before the creation, and this failures will not
1574 * be caught by sk_state_change()
1575 */
1576 mptcp_pm_close_subflow(msk);
1577 return err;
1578}
1579
1580static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1581{
1582#ifdef CONFIG_SOCK_CGROUP_DATA
1583 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1584 *child_skcd = &child->sk_cgrp_data;
1585
1586 /* only the additional subflows created by kworkers have to be modified */
1587 if (cgroup_id(cgrp: sock_cgroup_ptr(skcd: parent_skcd)) !=
1588 cgroup_id(cgrp: sock_cgroup_ptr(skcd: child_skcd))) {
1589#ifdef CONFIG_MEMCG
1590 struct mem_cgroup *memcg = parent->sk_memcg;
1591
1592 mem_cgroup_sk_free(sk: child);
1593 if (memcg && css_tryget(css: &memcg->css))
1594 child->sk_memcg = memcg;
1595#endif /* CONFIG_MEMCG */
1596
1597 cgroup_sk_free(skcd: child_skcd);
1598 *child_skcd = *parent_skcd;
1599 cgroup_sk_clone(skcd: child_skcd);
1600 }
1601#endif /* CONFIG_SOCK_CGROUP_DATA */
1602}
1603
1604static void mptcp_subflow_ops_override(struct sock *ssk)
1605{
1606#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1607 if (ssk->sk_prot == &tcpv6_prot)
1608 ssk->sk_prot = &tcpv6_prot_override;
1609 else
1610#endif
1611 ssk->sk_prot = &tcp_prot_override;
1612}
1613
1614static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1615{
1616#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1617 if (ssk->sk_prot == &tcpv6_prot_override)
1618 ssk->sk_prot = &tcpv6_prot;
1619 else
1620#endif
1621 ssk->sk_prot = &tcp_prot;
1622}
1623
1624int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1625 struct socket **new_sock)
1626{
1627 struct mptcp_subflow_context *subflow;
1628 struct net *net = sock_net(sk);
1629 struct socket *sf;
1630 int err;
1631
1632 /* un-accepted server sockets can reach here - on bad configuration
1633 * bail early to avoid greater trouble later
1634 */
1635 if (unlikely(!sk->sk_socket))
1636 return -EINVAL;
1637
1638 err = sock_create_kern(net, family, type: SOCK_STREAM, IPPROTO_TCP, res: &sf);
1639 if (err)
1640 return err;
1641
1642 lock_sock_nested(sk: sf->sk, SINGLE_DEPTH_NESTING);
1643
1644 err = security_mptcp_add_subflow(sk, ssk: sf->sk);
1645 if (err)
1646 goto err_free;
1647
1648 /* the newly created socket has to be in the same cgroup as its parent */
1649 mptcp_attach_cgroup(parent: sk, child: sf->sk);
1650
1651 /* kernel sockets do not by default acquire net ref, but TCP timer
1652 * needs it.
1653 * Update ns_tracker to current stack trace and refcounted tracker.
1654 */
1655 __netns_tracker_free(net, tracker: &sf->sk->ns_tracker, refcounted: false);
1656 sf->sk->sk_net_refcnt = 1;
1657 get_net_track(net, tracker: &sf->sk->ns_tracker, GFP_KERNEL);
1658 sock_inuse_add(net, val: 1);
1659 err = tcp_set_ulp(sk: sf->sk, name: "mptcp");
1660 if (err)
1661 goto err_free;
1662
1663 mptcp_sockopt_sync_locked(mptcp_sk(sk), ssk: sf->sk);
1664 release_sock(sk: sf->sk);
1665
1666 /* the newly created socket really belongs to the owning MPTCP master
1667 * socket, even if for additional subflows the allocation is performed
1668 * by a kernel workqueue. Adjust inode references, so that the
1669 * procfs/diag interfaces really show this one belonging to the correct
1670 * user.
1671 */
1672 SOCK_INODE(socket: sf)->i_ino = SOCK_INODE(socket: sk->sk_socket)->i_ino;
1673 SOCK_INODE(socket: sf)->i_uid = SOCK_INODE(socket: sk->sk_socket)->i_uid;
1674 SOCK_INODE(socket: sf)->i_gid = SOCK_INODE(socket: sk->sk_socket)->i_gid;
1675
1676 subflow = mptcp_subflow_ctx(sk: sf->sk);
1677 pr_debug("subflow=%p", subflow);
1678
1679 *new_sock = sf;
1680 sock_hold(sk);
1681 subflow->conn = sk;
1682 mptcp_subflow_ops_override(ssk: sf->sk);
1683
1684 return 0;
1685
1686err_free:
1687 release_sock(sk: sf->sk);
1688 sock_release(sock: sf);
1689 return err;
1690}
1691
1692static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1693 gfp_t priority)
1694{
1695 struct inet_connection_sock *icsk = inet_csk(sk);
1696 struct mptcp_subflow_context *ctx;
1697
1698 ctx = kzalloc(size: sizeof(*ctx), flags: priority);
1699 if (!ctx)
1700 return NULL;
1701
1702 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1703 INIT_LIST_HEAD(list: &ctx->node);
1704 INIT_LIST_HEAD(list: &ctx->delegated_node);
1705
1706 pr_debug("subflow=%p", ctx);
1707
1708 ctx->tcp_sock = sk;
1709
1710 return ctx;
1711}
1712
1713static void __subflow_state_change(struct sock *sk)
1714{
1715 struct socket_wq *wq;
1716
1717 rcu_read_lock();
1718 wq = rcu_dereference(sk->sk_wq);
1719 if (skwq_has_sleeper(wq))
1720 wake_up_interruptible_all(&wq->wait);
1721 rcu_read_unlock();
1722}
1723
1724static bool subflow_is_done(const struct sock *sk)
1725{
1726 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1727}
1728
1729static void subflow_state_change(struct sock *sk)
1730{
1731 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1732 struct sock *parent = subflow->conn;
1733 struct mptcp_sock *msk;
1734
1735 __subflow_state_change(sk);
1736
1737 msk = mptcp_sk(parent);
1738 if (subflow_simultaneous_connect(sk)) {
1739 mptcp_do_fallback(ssk: sk);
1740 mptcp_rcv_space_init(msk, ssk: sk);
1741 pr_fallback(msk);
1742 subflow->conn_finished = 1;
1743 mptcp_set_connected(sk: parent);
1744 }
1745
1746 /* as recvmsg() does not acquire the subflow socket for ssk selection
1747 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1748 * the data available machinery here.
1749 */
1750 if (mptcp_subflow_data_available(sk))
1751 mptcp_data_ready(sk: parent, ssk: sk);
1752 else if (unlikely(sk->sk_err))
1753 subflow_error_report(ssk: sk);
1754
1755 subflow_sched_work_if_closed(mptcp_sk(parent), ssk: sk);
1756
1757 /* when the fallback subflow closes the rx side, trigger a 'dummy'
1758 * ingress data fin, so that the msk state will follow along
1759 */
1760 if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
1761 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), use_64bit: true))
1762 mptcp_schedule_work(sk: parent);
1763}
1764
1765void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1766{
1767 struct request_sock_queue *queue = &inet_csk(sk: listener_ssk)->icsk_accept_queue;
1768 struct request_sock *req, *head, *tail;
1769 struct mptcp_subflow_context *subflow;
1770 struct sock *sk, *ssk;
1771
1772 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
1773 * Splice the req list, so that accept() can not reach the pending ssk after
1774 * the listener socket is released below.
1775 */
1776 spin_lock_bh(lock: &queue->rskq_lock);
1777 head = queue->rskq_accept_head;
1778 tail = queue->rskq_accept_tail;
1779 queue->rskq_accept_head = NULL;
1780 queue->rskq_accept_tail = NULL;
1781 spin_unlock_bh(lock: &queue->rskq_lock);
1782
1783 if (!head)
1784 return;
1785
1786 /* can't acquire the msk socket lock under the subflow one,
1787 * or will cause ABBA deadlock
1788 */
1789 release_sock(sk: listener_ssk);
1790
1791 for (req = head; req; req = req->dl_next) {
1792 ssk = req->sk;
1793 if (!sk_is_mptcp(sk: ssk))
1794 continue;
1795
1796 subflow = mptcp_subflow_ctx(sk: ssk);
1797 if (!subflow || !subflow->conn)
1798 continue;
1799
1800 sk = subflow->conn;
1801 sock_hold(sk);
1802
1803 lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1804 __mptcp_unaccepted_force_close(sk);
1805 release_sock(sk);
1806
1807 /* lockdep will report a false positive ABBA deadlock
1808 * between cancel_work_sync and the listener socket.
1809 * The involved locks belong to different sockets WRT
1810 * the existing AB chain.
1811 * Using a per socket key is problematic as key
1812 * deregistration requires process context and must be
1813 * performed at socket disposal time, in atomic
1814 * context.
1815 * Just tell lockdep to consider the listener socket
1816 * released here.
1817 */
1818 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1819 mptcp_cancel_work(sk);
1820 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
1821
1822 sock_put(sk);
1823 }
1824
1825 /* we are still under the listener msk socket lock */
1826 lock_sock_nested(sk: listener_ssk, SINGLE_DEPTH_NESTING);
1827
1828 /* restore the listener queue, to let the TCP code clean it up */
1829 spin_lock_bh(lock: &queue->rskq_lock);
1830 WARN_ON_ONCE(queue->rskq_accept_head);
1831 queue->rskq_accept_head = head;
1832 queue->rskq_accept_tail = tail;
1833 spin_unlock_bh(lock: &queue->rskq_lock);
1834}
1835
1836static int subflow_ulp_init(struct sock *sk)
1837{
1838 struct inet_connection_sock *icsk = inet_csk(sk);
1839 struct mptcp_subflow_context *ctx;
1840 struct tcp_sock *tp = tcp_sk(sk);
1841 int err = 0;
1842
1843 /* disallow attaching ULP to a socket unless it has been
1844 * created with sock_create_kern()
1845 */
1846 if (!sk->sk_kern_sock) {
1847 err = -EOPNOTSUPP;
1848 goto out;
1849 }
1850
1851 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1852 if (!ctx) {
1853 err = -ENOMEM;
1854 goto out;
1855 }
1856
1857 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1858
1859 tp->is_mptcp = 1;
1860 ctx->icsk_af_ops = icsk->icsk_af_ops;
1861 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1862 ctx->tcp_state_change = sk->sk_state_change;
1863 ctx->tcp_error_report = sk->sk_error_report;
1864
1865 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1866 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1867
1868 sk->sk_data_ready = subflow_data_ready;
1869 sk->sk_write_space = subflow_write_space;
1870 sk->sk_state_change = subflow_state_change;
1871 sk->sk_error_report = subflow_error_report;
1872out:
1873 return err;
1874}
1875
1876static void subflow_ulp_release(struct sock *ssk)
1877{
1878 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(sk: ssk);
1879 bool release = true;
1880 struct sock *sk;
1881
1882 if (!ctx)
1883 return;
1884
1885 sk = ctx->conn;
1886 if (sk) {
1887 /* if the msk has been orphaned, keep the ctx
1888 * alive, will be freed by __mptcp_close_ssk(),
1889 * when the subflow is still unaccepted
1890 */
1891 release = ctx->disposable || list_empty(head: &ctx->node);
1892
1893 /* inet_child_forget() does not call sk_state_change(),
1894 * explicitly trigger the socket close machinery
1895 */
1896 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
1897 addr: &mptcp_sk(sk)->flags))
1898 mptcp_schedule_work(sk);
1899 sock_put(sk);
1900 }
1901
1902 mptcp_subflow_ops_undo_override(ssk);
1903 if (release)
1904 kfree_rcu(ctx, rcu);
1905}
1906
1907static void subflow_ulp_clone(const struct request_sock *req,
1908 struct sock *newsk,
1909 const gfp_t priority)
1910{
1911 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(rsk: req);
1912 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(sk: newsk);
1913 struct mptcp_subflow_context *new_ctx;
1914
1915 if (!tcp_rsk(req)->is_mptcp ||
1916 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1917 subflow_ulp_fallback(sk: newsk, old_ctx);
1918 return;
1919 }
1920
1921 new_ctx = subflow_create_ctx(sk: newsk, priority);
1922 if (!new_ctx) {
1923 subflow_ulp_fallback(sk: newsk, old_ctx);
1924 return;
1925 }
1926
1927 new_ctx->conn_finished = 1;
1928 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1929 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1930 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1931 new_ctx->rel_write_seq = 1;
1932 new_ctx->tcp_sock = newsk;
1933
1934 if (subflow_req->mp_capable) {
1935 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1936 * is fully established only after we receive the remote key
1937 */
1938 new_ctx->mp_capable = 1;
1939 new_ctx->local_key = subflow_req->local_key;
1940 new_ctx->token = subflow_req->token;
1941 new_ctx->ssn_offset = subflow_req->ssn_offset;
1942 new_ctx->idsn = subflow_req->idsn;
1943
1944 /* this is the first subflow, id is always 0 */
1945 new_ctx->local_id_valid = 1;
1946 } else if (subflow_req->mp_join) {
1947 new_ctx->ssn_offset = subflow_req->ssn_offset;
1948 new_ctx->mp_join = 1;
1949 new_ctx->fully_established = 1;
1950 new_ctx->remote_key_valid = 1;
1951 new_ctx->backup = subflow_req->backup;
1952 new_ctx->remote_id = subflow_req->remote_id;
1953 new_ctx->token = subflow_req->token;
1954 new_ctx->thmac = subflow_req->thmac;
1955
1956 /* the subflow req id is valid, fetched via subflow_check_req()
1957 * and subflow_token_join_request()
1958 */
1959 subflow_set_local_id(subflow: new_ctx, local_id: subflow_req->local_id);
1960 }
1961}
1962
1963static void tcp_release_cb_override(struct sock *ssk)
1964{
1965 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk: ssk);
1966 long status;
1967
1968 /* process and clear all the pending actions, but leave the subflow into
1969 * the napi queue. To respect locking, only the same CPU that originated
1970 * the action can touch the list. mptcp_napi_poll will take care of it.
1971 */
1972 status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0);
1973 if (status)
1974 mptcp_subflow_process_delegated(ssk, actions: status);
1975
1976 tcp_release_cb(sk: ssk);
1977}
1978
1979static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1980 .name = "mptcp",
1981 .owner = THIS_MODULE,
1982 .init = subflow_ulp_init,
1983 .release = subflow_ulp_release,
1984 .clone = subflow_ulp_clone,
1985};
1986
1987static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1988{
1989 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1990
1991 subflow_ops->slab = kmem_cache_create(name: subflow_ops->slab_name,
1992 size: subflow_ops->obj_size, align: 0,
1993 SLAB_ACCOUNT |
1994 SLAB_TYPESAFE_BY_RCU,
1995 NULL);
1996 if (!subflow_ops->slab)
1997 return -ENOMEM;
1998
1999 return 0;
2000}
2001
2002void __init mptcp_subflow_init(void)
2003{
2004 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
2005 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
2006 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
2007
2008 if (subflow_ops_init(subflow_ops: &mptcp_subflow_v4_request_sock_ops) != 0)
2009 panic(fmt: "MPTCP: failed to init subflow v4 request sock ops\n");
2010
2011 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
2012 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
2013 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
2014
2015 subflow_specific = ipv4_specific;
2016 subflow_specific.conn_request = subflow_v4_conn_request;
2017 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
2018 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
2019 subflow_specific.rebuild_header = subflow_rebuild_header;
2020
2021 tcp_prot_override = tcp_prot;
2022 tcp_prot_override.release_cb = tcp_release_cb_override;
2023
2024#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2025 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock
2026 * structures for v4 and v6 have the same size. It should not changed in
2027 * the future but better to make sure to be warned if it is no longer
2028 * the case.
2029 */
2030 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
2031
2032 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
2033 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
2034 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
2035
2036 if (subflow_ops_init(subflow_ops: &mptcp_subflow_v6_request_sock_ops) != 0)
2037 panic(fmt: "MPTCP: failed to init subflow v6 request sock ops\n");
2038
2039 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
2040 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
2041 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
2042
2043 subflow_v6_specific = ipv6_specific;
2044 subflow_v6_specific.conn_request = subflow_v6_conn_request;
2045 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
2046 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
2047 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
2048
2049 subflow_v6m_specific = subflow_v6_specific;
2050 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
2051 subflow_v6m_specific.send_check = ipv4_specific.send_check;
2052 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
2053 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
2054 subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
2055
2056 tcpv6_prot_override = tcpv6_prot;
2057 tcpv6_prot_override.release_cb = tcp_release_cb_override;
2058#endif
2059
2060 mptcp_diag_subflow_init(ops: &subflow_ulp_ops);
2061
2062 if (tcp_register_ulp(type: &subflow_ulp_ops) != 0)
2063 panic(fmt: "MPTCP: failed to register subflows to ULP\n");
2064}
2065

source code of linux/net/mptcp/subflow.c