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 #include <trace/events/sock.h>
30
31 static void mptcp_subflow_ops_undo_override(struct sock *ssk);
32
SUBFLOW_REQ_INC_STATS(struct request_sock * req,enum linux_mptcp_mib_field field)33 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
34 enum linux_mptcp_mib_field field)
35 {
36 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
37 }
38
subflow_req_destructor(struct request_sock * req)39 static void subflow_req_destructor(struct request_sock *req)
40 {
41 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
42
43 pr_debug("subflow_req=%p\n", subflow_req);
44
45 if (subflow_req->msk)
46 sock_put((struct sock *)subflow_req->msk);
47
48 mptcp_token_destroy_request(req);
49 }
50
subflow_generate_hmac(u64 key1,u64 key2,u32 nonce1,u32 nonce2,void * hmac)51 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
52 void *hmac)
53 {
54 u8 msg[8];
55
56 put_unaligned_be32(nonce1, &msg[0]);
57 put_unaligned_be32(nonce2, &msg[4]);
58
59 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
60 }
61
mptcp_can_accept_new_subflow(const struct mptcp_sock * msk)62 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
63 {
64 return mptcp_is_fully_established((void *)msk) &&
65 ((mptcp_pm_is_userspace(msk) &&
66 mptcp_userspace_pm_active(msk)) ||
67 READ_ONCE(msk->pm.accept_subflow));
68 }
69
70 /* validate received token and create truncated hmac and nonce for SYN-ACK */
subflow_req_create_thmac(struct mptcp_subflow_request_sock * subflow_req)71 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
72 {
73 struct mptcp_sock *msk = subflow_req->msk;
74 u8 hmac[SHA256_DIGEST_SIZE];
75
76 get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
77
78 subflow_generate_hmac(msk->local_key, msk->remote_key,
79 subflow_req->local_nonce,
80 subflow_req->remote_nonce, hmac);
81
82 subflow_req->thmac = get_unaligned_be64(hmac);
83 }
84
subflow_token_join_request(struct request_sock * req)85 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
86 {
87 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
88 struct mptcp_sock *msk;
89 int local_id;
90
91 msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
92 if (!msk) {
93 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
94 return NULL;
95 }
96
97 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
98 if (local_id < 0) {
99 sock_put((struct sock *)msk);
100 return NULL;
101 }
102 subflow_req->local_id = local_id;
103 subflow_req->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)req);
104
105 return msk;
106 }
107
subflow_init_req(struct request_sock * req,const struct sock * sk_listener)108 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
109 {
110 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
111
112 subflow_req->mp_capable = 0;
113 subflow_req->mp_join = 0;
114 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
115 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
116 subflow_req->msk = NULL;
117 mptcp_token_init_request(req);
118 }
119
subflow_use_different_sport(struct mptcp_sock * msk,const struct sock * sk)120 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
121 {
122 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
123 }
124
subflow_add_reset_reason(struct sk_buff * skb,u8 reason)125 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
126 {
127 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
128
129 if (mpext) {
130 memset(mpext, 0, sizeof(*mpext));
131 mpext->reset_reason = reason;
132 }
133 }
134
subflow_reset_req_endp(struct request_sock * req,struct sk_buff * skb)135 static int subflow_reset_req_endp(struct request_sock *req, struct sk_buff *skb)
136 {
137 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEENDPATTEMPT);
138 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
139 return -EPERM;
140 }
141
142 /* Init mptcp request socket.
143 *
144 * Returns an error code if a JOIN has failed and a TCP reset
145 * should be sent.
146 */
subflow_check_req(struct request_sock * req,const struct sock * sk_listener,struct sk_buff * skb)147 static int subflow_check_req(struct request_sock *req,
148 const struct sock *sk_listener,
149 struct sk_buff *skb)
150 {
151 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
152 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
153 struct mptcp_options_received mp_opt;
154 bool opt_mp_capable, opt_mp_join;
155
156 pr_debug("subflow_req=%p, listener=%p\n", subflow_req, listener);
157
158 #ifdef CONFIG_TCP_MD5SIG
159 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
160 * TCP option space.
161 */
162 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
163 return -EINVAL;
164 #endif
165
166 mptcp_get_options(skb, &mp_opt);
167
168 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN);
169 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN);
170 if (opt_mp_capable) {
171 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
172
173 if (unlikely(listener->pm_listener))
174 return subflow_reset_req_endp(req, skb);
175 if (opt_mp_join)
176 return 0;
177 } else if (opt_mp_join) {
178 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
179
180 if (mp_opt.backup)
181 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNBACKUPRX);
182 } else if (unlikely(listener->pm_listener)) {
183 return subflow_reset_req_endp(req, skb);
184 }
185
186 if (opt_mp_capable && listener->request_mptcp) {
187 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
188
189 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
190 again:
191 do {
192 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
193 } while (subflow_req->local_key == 0);
194
195 if (unlikely(req->syncookie)) {
196 mptcp_crypto_key_sha(subflow_req->local_key,
197 &subflow_req->token,
198 &subflow_req->idsn);
199 if (mptcp_token_exists(subflow_req->token)) {
200 if (retries-- > 0)
201 goto again;
202 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
203 } else {
204 subflow_req->mp_capable = 1;
205 }
206 return 0;
207 }
208
209 err = mptcp_token_new_request(req);
210 if (err == 0)
211 subflow_req->mp_capable = 1;
212 else if (retries-- > 0)
213 goto again;
214 else
215 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
216
217 } else if (opt_mp_join && listener->request_mptcp) {
218 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
219 subflow_req->mp_join = 1;
220 subflow_req->backup = mp_opt.backup;
221 subflow_req->remote_id = mp_opt.join_id;
222 subflow_req->token = mp_opt.token;
223 subflow_req->remote_nonce = mp_opt.nonce;
224 subflow_req->msk = subflow_token_join_request(req);
225
226 /* Can't fall back to TCP in this case. */
227 if (!subflow_req->msk) {
228 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
229 return -EPERM;
230 }
231
232 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
233 pr_debug("syn inet_sport=%d %d\n",
234 ntohs(inet_sk(sk_listener)->inet_sport),
235 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
236 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
237 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
238 return -EPERM;
239 }
240 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
241 }
242
243 subflow_req_create_thmac(subflow_req);
244
245 if (unlikely(req->syncookie)) {
246 if (mptcp_can_accept_new_subflow(subflow_req->msk))
247 subflow_init_req_cookie_join_save(subflow_req, skb);
248 else
249 return -EPERM;
250 }
251
252 pr_debug("token=%u, remote_nonce=%u msk=%p\n", subflow_req->token,
253 subflow_req->remote_nonce, subflow_req->msk);
254 }
255
256 return 0;
257 }
258
mptcp_subflow_init_cookie_req(struct request_sock * req,const struct sock * sk_listener,struct sk_buff * skb)259 int mptcp_subflow_init_cookie_req(struct request_sock *req,
260 const struct sock *sk_listener,
261 struct sk_buff *skb)
262 {
263 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
264 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
265 struct mptcp_options_received mp_opt;
266 bool opt_mp_capable, opt_mp_join;
267 int err;
268
269 subflow_init_req(req, sk_listener);
270 mptcp_get_options(skb, &mp_opt);
271
272 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK);
273 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK);
274 if (opt_mp_capable && opt_mp_join)
275 return -EINVAL;
276
277 if (opt_mp_capable && listener->request_mptcp) {
278 if (mp_opt.sndr_key == 0)
279 return -EINVAL;
280
281 subflow_req->local_key = mp_opt.rcvr_key;
282 err = mptcp_token_new_request(req);
283 if (err)
284 return err;
285
286 subflow_req->mp_capable = 1;
287 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
288 } else if (opt_mp_join && listener->request_mptcp) {
289 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
290 return -EINVAL;
291
292 subflow_req->mp_join = 1;
293 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
294 }
295
296 return 0;
297 }
298 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
299
subflow_v4_route_req(const struct sock * sk,struct sk_buff * skb,struct flowi * fl,struct request_sock * req)300 static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
301 struct sk_buff *skb,
302 struct flowi *fl,
303 struct request_sock *req)
304 {
305 struct dst_entry *dst;
306 int err;
307
308 tcp_rsk(req)->is_mptcp = 1;
309 subflow_init_req(req, sk);
310
311 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
312 if (!dst)
313 return NULL;
314
315 err = subflow_check_req(req, sk, skb);
316 if (err == 0)
317 return dst;
318
319 dst_release(dst);
320 if (!req->syncookie)
321 tcp_request_sock_ops.send_reset(sk, skb);
322 return NULL;
323 }
324
subflow_prep_synack(const struct sock * sk,struct request_sock * req,struct tcp_fastopen_cookie * foc,enum tcp_synack_type synack_type)325 static void subflow_prep_synack(const struct sock *sk, struct request_sock *req,
326 struct tcp_fastopen_cookie *foc,
327 enum tcp_synack_type synack_type)
328 {
329 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
330 struct inet_request_sock *ireq = inet_rsk(req);
331
332 /* clear tstamp_ok, as needed depending on cookie */
333 if (foc && foc->len > -1)
334 ireq->tstamp_ok = 0;
335
336 if (synack_type == TCP_SYNACK_FASTOPEN)
337 mptcp_fastopen_subflow_synack_set_params(subflow, req);
338 }
339
subflow_v4_send_synack(const struct sock * sk,struct dst_entry * dst,struct flowi * fl,struct request_sock * req,struct tcp_fastopen_cookie * foc,enum tcp_synack_type synack_type,struct sk_buff * syn_skb)340 static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
341 struct flowi *fl,
342 struct request_sock *req,
343 struct tcp_fastopen_cookie *foc,
344 enum tcp_synack_type synack_type,
345 struct sk_buff *syn_skb)
346 {
347 subflow_prep_synack(sk, req, foc, synack_type);
348
349 return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc,
350 synack_type, syn_skb);
351 }
352
353 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
subflow_v6_send_synack(const struct sock * sk,struct dst_entry * dst,struct flowi * fl,struct request_sock * req,struct tcp_fastopen_cookie * foc,enum tcp_synack_type synack_type,struct sk_buff * syn_skb)354 static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
355 struct flowi *fl,
356 struct request_sock *req,
357 struct tcp_fastopen_cookie *foc,
358 enum tcp_synack_type synack_type,
359 struct sk_buff *syn_skb)
360 {
361 subflow_prep_synack(sk, req, foc, synack_type);
362
363 return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc,
364 synack_type, syn_skb);
365 }
366
subflow_v6_route_req(const struct sock * sk,struct sk_buff * skb,struct flowi * fl,struct request_sock * req)367 static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
368 struct sk_buff *skb,
369 struct flowi *fl,
370 struct request_sock *req)
371 {
372 struct dst_entry *dst;
373 int err;
374
375 tcp_rsk(req)->is_mptcp = 1;
376 subflow_init_req(req, sk);
377
378 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
379 if (!dst)
380 return NULL;
381
382 err = subflow_check_req(req, sk, skb);
383 if (err == 0)
384 return dst;
385
386 dst_release(dst);
387 if (!req->syncookie)
388 tcp6_request_sock_ops.send_reset(sk, skb);
389 return NULL;
390 }
391 #endif
392
393 /* validate received truncated hmac and create hmac for third ACK */
subflow_thmac_valid(struct mptcp_subflow_context * subflow)394 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
395 {
396 u8 hmac[SHA256_DIGEST_SIZE];
397 u64 thmac;
398
399 subflow_generate_hmac(subflow->remote_key, subflow->local_key,
400 subflow->remote_nonce, subflow->local_nonce,
401 hmac);
402
403 thmac = get_unaligned_be64(hmac);
404 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
405 subflow, subflow->token, thmac, subflow->thmac);
406
407 return thmac == subflow->thmac;
408 }
409
mptcp_subflow_reset(struct sock * ssk)410 void mptcp_subflow_reset(struct sock *ssk)
411 {
412 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
413 struct sock *sk = subflow->conn;
414
415 /* mptcp_mp_fail_no_response() can reach here on an already closed
416 * socket
417 */
418 if (ssk->sk_state == TCP_CLOSE)
419 return;
420
421 /* must hold: tcp_done() could drop last reference on parent */
422 sock_hold(sk);
423
424 tcp_send_active_reset(ssk, GFP_ATOMIC);
425 tcp_done(ssk);
426 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
427 mptcp_schedule_work(sk);
428
429 sock_put(sk);
430 }
431
subflow_use_different_dport(struct mptcp_sock * msk,const struct sock * sk)432 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
433 {
434 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
435 }
436
__mptcp_sync_state(struct sock * sk,int state)437 void __mptcp_sync_state(struct sock *sk, int state)
438 {
439 struct mptcp_subflow_context *subflow;
440 struct mptcp_sock *msk = mptcp_sk(sk);
441 struct sock *ssk = msk->first;
442
443 subflow = mptcp_subflow_ctx(ssk);
444 __mptcp_propagate_sndbuf(sk, ssk);
445 if (!msk->rcvspace_init)
446 mptcp_rcv_space_init(msk, ssk);
447
448 if (sk->sk_state == TCP_SYN_SENT) {
449 /* subflow->idsn is always available is TCP_SYN_SENT state,
450 * even for the FASTOPEN scenarios
451 */
452 WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
453 WRITE_ONCE(msk->snd_nxt, msk->write_seq);
454 mptcp_set_state(sk, state);
455 sk->sk_state_change(sk);
456 }
457 }
458
subflow_set_remote_key(struct mptcp_sock * msk,struct mptcp_subflow_context * subflow,const struct mptcp_options_received * mp_opt)459 static void subflow_set_remote_key(struct mptcp_sock *msk,
460 struct mptcp_subflow_context *subflow,
461 const struct mptcp_options_received *mp_opt)
462 {
463 /* active MPC subflow will reach here multiple times:
464 * at subflow_finish_connect() time and at 4th ack time
465 */
466 if (subflow->remote_key_valid)
467 return;
468
469 subflow->remote_key_valid = 1;
470 subflow->remote_key = mp_opt->sndr_key;
471 mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
472 subflow->iasn++;
473
474 WRITE_ONCE(msk->remote_key, subflow->remote_key);
475 WRITE_ONCE(msk->ack_seq, subflow->iasn);
476 WRITE_ONCE(msk->can_ack, true);
477 atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
478 }
479
mptcp_propagate_state(struct sock * sk,struct sock * ssk,struct mptcp_subflow_context * subflow,const struct mptcp_options_received * mp_opt)480 static void mptcp_propagate_state(struct sock *sk, struct sock *ssk,
481 struct mptcp_subflow_context *subflow,
482 const struct mptcp_options_received *mp_opt)
483 {
484 struct mptcp_sock *msk = mptcp_sk(sk);
485
486 mptcp_data_lock(sk);
487 if (mp_opt) {
488 /* Options are available only in the non fallback cases
489 * avoid updating rx path fields otherwise
490 */
491 WRITE_ONCE(msk->snd_una, subflow->idsn + 1);
492 WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd);
493 subflow_set_remote_key(msk, subflow, mp_opt);
494 }
495
496 if (!sock_owned_by_user(sk)) {
497 __mptcp_sync_state(sk, ssk->sk_state);
498 } else {
499 msk->pending_state = ssk->sk_state;
500 __set_bit(MPTCP_SYNC_STATE, &msk->cb_flags);
501 }
502 mptcp_data_unlock(sk);
503 }
504
subflow_finish_connect(struct sock * sk,const struct sk_buff * skb)505 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
506 {
507 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
508 struct mptcp_options_received mp_opt;
509 struct sock *parent = subflow->conn;
510 struct mptcp_sock *msk;
511
512 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
513
514 /* be sure no special action on any packet other than syn-ack */
515 if (subflow->conn_finished)
516 return;
517
518 msk = mptcp_sk(parent);
519 subflow->rel_write_seq = 1;
520 subflow->conn_finished = 1;
521 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
522 pr_debug("subflow=%p synack seq=%x\n", subflow, subflow->ssn_offset);
523
524 mptcp_get_options(skb, &mp_opt);
525 if (subflow->request_mptcp) {
526 if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) {
527 MPTCP_INC_STATS(sock_net(sk),
528 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
529 mptcp_do_fallback(sk);
530 pr_fallback(msk);
531 goto fallback;
532 }
533
534 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
535 WRITE_ONCE(msk->csum_enabled, true);
536 if (mp_opt.deny_join_id0)
537 WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
538 subflow->mp_capable = 1;
539 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
540 mptcp_finish_connect(sk);
541 mptcp_propagate_state(parent, sk, subflow, &mp_opt);
542 } else if (subflow->request_join) {
543 u8 hmac[SHA256_DIGEST_SIZE];
544
545 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) {
546 subflow->reset_reason = MPTCP_RST_EMPTCP;
547 goto do_reset;
548 }
549
550 subflow->backup = mp_opt.backup;
551 subflow->thmac = mp_opt.thmac;
552 subflow->remote_nonce = mp_opt.nonce;
553 WRITE_ONCE(subflow->remote_id, mp_opt.join_id);
554 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d\n",
555 subflow, subflow->thmac, subflow->remote_nonce,
556 subflow->backup);
557
558 if (!subflow_thmac_valid(subflow)) {
559 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
560 subflow->reset_reason = MPTCP_RST_EMPTCP;
561 goto do_reset;
562 }
563
564 if (!mptcp_finish_join(sk))
565 goto do_reset;
566
567 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
568 subflow->local_nonce,
569 subflow->remote_nonce,
570 hmac);
571 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
572
573 subflow->mp_join = 1;
574 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
575
576 if (subflow->backup)
577 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKBACKUPRX);
578
579 if (subflow_use_different_dport(msk, sk)) {
580 pr_debug("synack inet_dport=%d %d\n",
581 ntohs(inet_sk(sk)->inet_dport),
582 ntohs(inet_sk(parent)->inet_dport));
583 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
584 }
585 } else if (mptcp_check_fallback(sk)) {
586 fallback:
587 mptcp_propagate_state(parent, sk, subflow, NULL);
588 }
589 return;
590
591 do_reset:
592 subflow->reset_transient = 0;
593 mptcp_subflow_reset(sk);
594 }
595
subflow_set_local_id(struct mptcp_subflow_context * subflow,int local_id)596 static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
597 {
598 WARN_ON_ONCE(local_id < 0 || local_id > 255);
599 WRITE_ONCE(subflow->local_id, local_id);
600 }
601
subflow_chk_local_id(struct sock * sk)602 static int subflow_chk_local_id(struct sock *sk)
603 {
604 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
605 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
606 int err;
607
608 if (likely(subflow->local_id >= 0))
609 return 0;
610
611 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
612 if (err < 0)
613 return err;
614
615 subflow_set_local_id(subflow, err);
616 subflow->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)sk);
617
618 return 0;
619 }
620
subflow_rebuild_header(struct sock * sk)621 static int subflow_rebuild_header(struct sock *sk)
622 {
623 int err = subflow_chk_local_id(sk);
624
625 if (unlikely(err < 0))
626 return err;
627
628 return inet_sk_rebuild_header(sk);
629 }
630
631 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
subflow_v6_rebuild_header(struct sock * sk)632 static int subflow_v6_rebuild_header(struct sock *sk)
633 {
634 int err = subflow_chk_local_id(sk);
635
636 if (unlikely(err < 0))
637 return err;
638
639 return inet6_sk_rebuild_header(sk);
640 }
641 #endif
642
643 static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
644 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
645
subflow_v4_conn_request(struct sock * sk,struct sk_buff * skb)646 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
647 {
648 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
649
650 pr_debug("subflow=%p\n", subflow);
651
652 /* Never answer to SYNs sent to broadcast or multicast */
653 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
654 goto drop;
655
656 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
657 &subflow_request_sock_ipv4_ops,
658 sk, skb);
659 drop:
660 tcp_listendrop(sk);
661 return 0;
662 }
663
subflow_v4_req_destructor(struct request_sock * req)664 static void subflow_v4_req_destructor(struct request_sock *req)
665 {
666 subflow_req_destructor(req);
667 tcp_request_sock_ops.destructor(req);
668 }
669
670 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
671 static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
672 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
673 static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
674 static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
675 static struct proto tcpv6_prot_override __ro_after_init;
676
subflow_v6_conn_request(struct sock * sk,struct sk_buff * skb)677 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
678 {
679 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
680
681 pr_debug("subflow=%p\n", subflow);
682
683 if (skb->protocol == htons(ETH_P_IP))
684 return subflow_v4_conn_request(sk, skb);
685
686 if (!ipv6_unicast_destination(skb))
687 goto drop;
688
689 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
690 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
691 return 0;
692 }
693
694 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
695 &subflow_request_sock_ipv6_ops, sk, skb);
696
697 drop:
698 tcp_listendrop(sk);
699 return 0; /* don't send reset */
700 }
701
subflow_v6_req_destructor(struct request_sock * req)702 static void subflow_v6_req_destructor(struct request_sock *req)
703 {
704 subflow_req_destructor(req);
705 tcp6_request_sock_ops.destructor(req);
706 }
707 #endif
708
mptcp_subflow_reqsk_alloc(const struct request_sock_ops * ops,struct sock * sk_listener,bool attach_listener)709 struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
710 struct sock *sk_listener,
711 bool attach_listener)
712 {
713 if (ops->family == AF_INET)
714 ops = &mptcp_subflow_v4_request_sock_ops;
715 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
716 else if (ops->family == AF_INET6)
717 ops = &mptcp_subflow_v6_request_sock_ops;
718 #endif
719
720 return inet_reqsk_alloc(ops, sk_listener, attach_listener);
721 }
722 EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
723
724 /* validate hmac received in third ACK */
subflow_hmac_valid(const struct request_sock * req,const struct mptcp_options_received * mp_opt)725 static bool subflow_hmac_valid(const struct request_sock *req,
726 const struct mptcp_options_received *mp_opt)
727 {
728 const struct mptcp_subflow_request_sock *subflow_req;
729 u8 hmac[SHA256_DIGEST_SIZE];
730 struct mptcp_sock *msk;
731
732 subflow_req = mptcp_subflow_rsk(req);
733 msk = subflow_req->msk;
734 if (!msk)
735 return false;
736
737 subflow_generate_hmac(msk->remote_key, msk->local_key,
738 subflow_req->remote_nonce,
739 subflow_req->local_nonce, hmac);
740
741 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
742 }
743
subflow_ulp_fallback(struct sock * sk,struct mptcp_subflow_context * old_ctx)744 static void subflow_ulp_fallback(struct sock *sk,
745 struct mptcp_subflow_context *old_ctx)
746 {
747 struct inet_connection_sock *icsk = inet_csk(sk);
748
749 mptcp_subflow_tcp_fallback(sk, old_ctx);
750 icsk->icsk_ulp_ops = NULL;
751 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
752 tcp_sk(sk)->is_mptcp = 0;
753
754 mptcp_subflow_ops_undo_override(sk);
755 }
756
mptcp_subflow_drop_ctx(struct sock * ssk)757 void mptcp_subflow_drop_ctx(struct sock *ssk)
758 {
759 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
760
761 if (!ctx)
762 return;
763
764 list_del(&mptcp_subflow_ctx(ssk)->node);
765 if (inet_csk(ssk)->icsk_ulp_ops) {
766 subflow_ulp_fallback(ssk, ctx);
767 if (ctx->conn)
768 sock_put(ctx->conn);
769 }
770
771 kfree_rcu(ctx, rcu);
772 }
773
__mptcp_subflow_fully_established(struct mptcp_sock * msk,struct mptcp_subflow_context * subflow,const struct mptcp_options_received * mp_opt)774 void __mptcp_subflow_fully_established(struct mptcp_sock *msk,
775 struct mptcp_subflow_context *subflow,
776 const struct mptcp_options_received *mp_opt)
777 {
778 subflow_set_remote_key(msk, subflow, mp_opt);
779 subflow->fully_established = 1;
780 WRITE_ONCE(msk->fully_established, true);
781
782 if (subflow->is_mptfo)
783 __mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt);
784 }
785
subflow_syn_recv_sock(const struct sock * sk,struct sk_buff * skb,struct request_sock * req,struct dst_entry * dst,struct request_sock * req_unhash,bool * own_req)786 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
787 struct sk_buff *skb,
788 struct request_sock *req,
789 struct dst_entry *dst,
790 struct request_sock *req_unhash,
791 bool *own_req)
792 {
793 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
794 struct mptcp_subflow_request_sock *subflow_req;
795 struct mptcp_options_received mp_opt;
796 bool fallback, fallback_is_fatal;
797 struct mptcp_sock *owner;
798 struct sock *child;
799
800 pr_debug("listener=%p, req=%p, conn=%p\n", listener, req, listener->conn);
801
802 /* After child creation we must look for MPC even when options
803 * are not parsed
804 */
805 mp_opt.suboptions = 0;
806
807 /* hopefully temporary handling for MP_JOIN+syncookie */
808 subflow_req = mptcp_subflow_rsk(req);
809 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
810 fallback = !tcp_rsk(req)->is_mptcp;
811 if (fallback)
812 goto create_child;
813
814 /* if the sk is MP_CAPABLE, we try to fetch the client key */
815 if (subflow_req->mp_capable) {
816 /* we can receive and accept an in-window, out-of-order pkt,
817 * which may not carry the MP_CAPABLE opt even on mptcp enabled
818 * paths: always try to extract the peer key, and fallback
819 * for packets missing it.
820 * Even OoO DSS packets coming legitly after dropped or
821 * reordered MPC will cause fallback, but we don't have other
822 * options.
823 */
824 mptcp_get_options(skb, &mp_opt);
825 if (!(mp_opt.suboptions &
826 (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK)))
827 fallback = true;
828
829 } else if (subflow_req->mp_join) {
830 mptcp_get_options(skb, &mp_opt);
831 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) ||
832 !subflow_hmac_valid(req, &mp_opt) ||
833 !mptcp_can_accept_new_subflow(subflow_req->msk)) {
834 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
835 fallback = true;
836 }
837 }
838
839 create_child:
840 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
841 req_unhash, own_req);
842
843 if (child && *own_req) {
844 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
845
846 tcp_rsk(req)->drop_req = false;
847
848 /* we need to fallback on ctx allocation failure and on pre-reqs
849 * checking above. In the latter scenario we additionally need
850 * to reset the context to non MPTCP status.
851 */
852 if (!ctx || fallback) {
853 if (fallback_is_fatal) {
854 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
855 goto dispose_child;
856 }
857 goto fallback;
858 }
859
860 /* ssk inherits options of listener sk */
861 ctx->setsockopt_seq = listener->setsockopt_seq;
862
863 if (ctx->mp_capable) {
864 ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req);
865 if (!ctx->conn)
866 goto fallback;
867
868 ctx->subflow_id = 1;
869 owner = mptcp_sk(ctx->conn);
870 mptcp_pm_new_connection(owner, child, 1);
871
872 /* with OoO packets we can reach here without ingress
873 * mpc option
874 */
875 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) {
876 mptcp_pm_fully_established(owner, child);
877 ctx->pm_notified = 1;
878 }
879 } else if (ctx->mp_join) {
880 owner = subflow_req->msk;
881 if (!owner) {
882 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
883 goto dispose_child;
884 }
885
886 /* move the msk reference ownership to the subflow */
887 subflow_req->msk = NULL;
888 ctx->conn = (struct sock *)owner;
889
890 if (subflow_use_different_sport(owner, sk)) {
891 pr_debug("ack inet_sport=%d %d\n",
892 ntohs(inet_sk(sk)->inet_sport),
893 ntohs(inet_sk((struct sock *)owner)->inet_sport));
894 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
895 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
896 goto dispose_child;
897 }
898 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
899 }
900
901 if (!mptcp_finish_join(child))
902 goto dispose_child;
903
904 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
905 tcp_rsk(req)->drop_req = true;
906 }
907 }
908
909 /* check for expected invariant - should never trigger, just help
910 * catching eariler subtle bugs
911 */
912 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
913 (!mptcp_subflow_ctx(child) ||
914 !mptcp_subflow_ctx(child)->conn));
915 return child;
916
917 dispose_child:
918 mptcp_subflow_drop_ctx(child);
919 tcp_rsk(req)->drop_req = true;
920 inet_csk_prepare_for_destroy_sock(child);
921 tcp_done(child);
922 req->rsk_ops->send_reset(sk, skb);
923
924 /* The last child reference will be released by the caller */
925 return child;
926
927 fallback:
928 if (fallback)
929 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
930 mptcp_subflow_drop_ctx(child);
931 return child;
932 }
933
934 static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
935 static struct proto tcp_prot_override __ro_after_init;
936
937 enum mapping_status {
938 MAPPING_OK,
939 MAPPING_INVALID,
940 MAPPING_EMPTY,
941 MAPPING_DATA_FIN,
942 MAPPING_DUMMY,
943 MAPPING_BAD_CSUM
944 };
945
dbg_bad_map(struct mptcp_subflow_context * subflow,u32 ssn)946 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
947 {
948 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d\n",
949 ssn, subflow->map_subflow_seq, subflow->map_data_len);
950 }
951
skb_is_fully_mapped(struct sock * ssk,struct sk_buff * skb)952 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
953 {
954 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
955 unsigned int skb_consumed;
956
957 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
958 if (unlikely(skb_consumed >= skb->len)) {
959 DEBUG_NET_WARN_ON_ONCE(1);
960 return true;
961 }
962
963 return skb->len - skb_consumed <= subflow->map_data_len -
964 mptcp_subflow_get_map_offset(subflow);
965 }
966
validate_mapping(struct sock * ssk,struct sk_buff * skb)967 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
968 {
969 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
970 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
971
972 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
973 /* Mapping covers data later in the subflow stream,
974 * currently unsupported.
975 */
976 dbg_bad_map(subflow, ssn);
977 return false;
978 }
979 if (unlikely(!before(ssn, subflow->map_subflow_seq +
980 subflow->map_data_len))) {
981 /* Mapping does covers past subflow data, invalid */
982 dbg_bad_map(subflow, ssn);
983 return false;
984 }
985 return true;
986 }
987
validate_data_csum(struct sock * ssk,struct sk_buff * skb,bool csum_reqd)988 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
989 bool csum_reqd)
990 {
991 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
992 u32 offset, seq, delta;
993 __sum16 csum;
994 int len;
995
996 if (!csum_reqd)
997 return MAPPING_OK;
998
999 /* mapping already validated on previous traversal */
1000 if (subflow->map_csum_len == subflow->map_data_len)
1001 return MAPPING_OK;
1002
1003 /* traverse the receive queue, ensuring it contains a full
1004 * DSS mapping and accumulating the related csum.
1005 * Preserve the accoumlate csum across multiple calls, to compute
1006 * the csum only once
1007 */
1008 delta = subflow->map_data_len - subflow->map_csum_len;
1009 for (;;) {
1010 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
1011 offset = seq - TCP_SKB_CB(skb)->seq;
1012
1013 /* if the current skb has not been accounted yet, csum its contents
1014 * up to the amount covered by the current DSS
1015 */
1016 if (offset < skb->len) {
1017 __wsum csum;
1018
1019 len = min(skb->len - offset, delta);
1020 csum = skb_checksum(skb, offset, len, 0);
1021 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
1022 subflow->map_csum_len);
1023
1024 delta -= len;
1025 subflow->map_csum_len += len;
1026 }
1027 if (delta == 0)
1028 break;
1029
1030 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
1031 /* if this subflow is closed, the partial mapping
1032 * will be never completed; flush the pending skbs, so
1033 * that subflow_sched_work_if_closed() can kick in
1034 */
1035 if (unlikely(ssk->sk_state == TCP_CLOSE))
1036 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1037 sk_eat_skb(ssk, skb);
1038
1039 /* not enough data to validate the csum */
1040 return MAPPING_EMPTY;
1041 }
1042
1043 /* the DSS mapping for next skbs will be validated later,
1044 * when a get_mapping_status call will process such skb
1045 */
1046 skb = skb->next;
1047 }
1048
1049 /* note that 'map_data_len' accounts only for the carried data, does
1050 * not include the eventual seq increment due to the data fin,
1051 * while the pseudo header requires the original DSS data len,
1052 * including that
1053 */
1054 csum = __mptcp_make_csum(subflow->map_seq,
1055 subflow->map_subflow_seq,
1056 subflow->map_data_len + subflow->map_data_fin,
1057 subflow->map_data_csum);
1058 if (unlikely(csum)) {
1059 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
1060 return MAPPING_BAD_CSUM;
1061 }
1062
1063 subflow->valid_csum_seen = 1;
1064 return MAPPING_OK;
1065 }
1066
get_mapping_status(struct sock * ssk,struct mptcp_sock * msk)1067 static enum mapping_status get_mapping_status(struct sock *ssk,
1068 struct mptcp_sock *msk)
1069 {
1070 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1071 bool csum_reqd = READ_ONCE(msk->csum_enabled);
1072 struct mptcp_ext *mpext;
1073 struct sk_buff *skb;
1074 u16 data_len;
1075 u64 map_seq;
1076
1077 skb = skb_peek(&ssk->sk_receive_queue);
1078 if (!skb)
1079 return MAPPING_EMPTY;
1080
1081 if (mptcp_check_fallback(ssk))
1082 return MAPPING_DUMMY;
1083
1084 mpext = mptcp_get_ext(skb);
1085 if (!mpext || !mpext->use_map) {
1086 if (!subflow->map_valid && !skb->len) {
1087 /* the TCP stack deliver 0 len FIN pkt to the receive
1088 * queue, that is the only 0len pkts ever expected here,
1089 * and we can admit no mapping only for 0 len pkts
1090 */
1091 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
1092 WARN_ONCE(1, "0len seq %d:%d flags %x",
1093 TCP_SKB_CB(skb)->seq,
1094 TCP_SKB_CB(skb)->end_seq,
1095 TCP_SKB_CB(skb)->tcp_flags);
1096 sk_eat_skb(ssk, skb);
1097 return MAPPING_EMPTY;
1098 }
1099
1100 if (!subflow->map_valid)
1101 return MAPPING_INVALID;
1102
1103 goto validate_seq;
1104 }
1105
1106 trace_get_mapping_status(mpext);
1107
1108 data_len = mpext->data_len;
1109 if (data_len == 0) {
1110 pr_debug("infinite mapping received\n");
1111 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
1112 return MAPPING_INVALID;
1113 }
1114
1115 if (mpext->data_fin == 1) {
1116 if (data_len == 1) {
1117 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
1118 mpext->dsn64);
1119 pr_debug("DATA_FIN with no payload seq=%llu\n", mpext->data_seq);
1120 if (subflow->map_valid) {
1121 /* A DATA_FIN might arrive in a DSS
1122 * option before the previous mapping
1123 * has been fully consumed. Continue
1124 * handling the existing mapping.
1125 */
1126 skb_ext_del(skb, SKB_EXT_MPTCP);
1127 return MAPPING_OK;
1128 } else {
1129 if (updated)
1130 mptcp_schedule_work((struct sock *)msk);
1131
1132 return MAPPING_DATA_FIN;
1133 }
1134 } else {
1135 u64 data_fin_seq = mpext->data_seq + data_len - 1;
1136
1137 /* If mpext->data_seq is a 32-bit value, data_fin_seq
1138 * must also be limited to 32 bits.
1139 */
1140 if (!mpext->dsn64)
1141 data_fin_seq &= GENMASK_ULL(31, 0);
1142
1143 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1144 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d\n",
1145 data_fin_seq, mpext->dsn64);
1146 }
1147
1148 /* Adjust for DATA_FIN using 1 byte of sequence space */
1149 data_len--;
1150 }
1151
1152 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1153 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1154
1155 if (subflow->map_valid) {
1156 /* Allow replacing only with an identical map */
1157 if (subflow->map_seq == map_seq &&
1158 subflow->map_subflow_seq == mpext->subflow_seq &&
1159 subflow->map_data_len == data_len &&
1160 subflow->map_csum_reqd == mpext->csum_reqd) {
1161 skb_ext_del(skb, SKB_EXT_MPTCP);
1162 goto validate_csum;
1163 }
1164
1165 /* If this skb data are fully covered by the current mapping,
1166 * the new map would need caching, which is not supported
1167 */
1168 if (skb_is_fully_mapped(ssk, skb)) {
1169 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1170 return MAPPING_INVALID;
1171 }
1172
1173 /* will validate the next map after consuming the current one */
1174 goto validate_csum;
1175 }
1176
1177 subflow->map_seq = map_seq;
1178 subflow->map_subflow_seq = mpext->subflow_seq;
1179 subflow->map_data_len = data_len;
1180 subflow->map_valid = 1;
1181 subflow->map_data_fin = mpext->data_fin;
1182 subflow->mpc_map = mpext->mpc_map;
1183 subflow->map_csum_reqd = mpext->csum_reqd;
1184 subflow->map_csum_len = 0;
1185 subflow->map_data_csum = csum_unfold(mpext->csum);
1186
1187 /* Cfr RFC 8684 Section 3.3.0 */
1188 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1189 return MAPPING_INVALID;
1190
1191 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n",
1192 subflow->map_seq, subflow->map_subflow_seq,
1193 subflow->map_data_len, subflow->map_csum_reqd,
1194 subflow->map_data_csum);
1195
1196 validate_seq:
1197 /* we revalidate valid mapping on new skb, because we must ensure
1198 * the current skb is completely covered by the available mapping
1199 */
1200 if (!validate_mapping(ssk, skb)) {
1201 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1202 return MAPPING_INVALID;
1203 }
1204
1205 skb_ext_del(skb, SKB_EXT_MPTCP);
1206
1207 validate_csum:
1208 return validate_data_csum(ssk, skb, csum_reqd);
1209 }
1210
mptcp_subflow_discard_data(struct sock * ssk,struct sk_buff * skb,u64 limit)1211 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1212 u64 limit)
1213 {
1214 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1215 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1216 struct tcp_sock *tp = tcp_sk(ssk);
1217 u32 offset, incr, avail_len;
1218
1219 offset = tp->copied_seq - TCP_SKB_CB(skb)->seq;
1220 if (WARN_ON_ONCE(offset > skb->len))
1221 goto out;
1222
1223 avail_len = skb->len - offset;
1224 incr = limit >= avail_len ? avail_len + fin : limit;
1225
1226 pr_debug("discarding=%d len=%d offset=%d seq=%d\n", incr, skb->len,
1227 offset, subflow->map_subflow_seq);
1228 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1229 tcp_sk(ssk)->copied_seq += incr;
1230
1231 out:
1232 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1233 sk_eat_skb(ssk, skb);
1234 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1235 subflow->map_valid = 0;
1236 }
1237
1238 /* sched mptcp worker to remove the subflow if no more data is pending */
subflow_sched_work_if_closed(struct mptcp_sock * msk,struct sock * ssk)1239 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1240 {
1241 struct sock *sk = (struct sock *)msk;
1242
1243 if (likely(ssk->sk_state != TCP_CLOSE &&
1244 (ssk->sk_state != TCP_CLOSE_WAIT ||
1245 inet_sk_state_load(sk) != TCP_ESTABLISHED)))
1246 return;
1247
1248 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1249 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
1250 mptcp_schedule_work(sk);
1251 }
1252
mptcp_subflow_fail(struct mptcp_sock * msk,struct sock * ssk)1253 static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1254 {
1255 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1256 unsigned long fail_tout;
1257
1258 /* greceful failure can happen only on the MPC subflow */
1259 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1260 return;
1261
1262 /* since the close timeout take precedence on the fail one,
1263 * no need to start the latter when the first is already set
1264 */
1265 if (sock_flag((struct sock *)msk, SOCK_DEAD))
1266 return;
1267
1268 /* we don't need extreme accuracy here, use a zero fail_tout as special
1269 * value meaning no fail timeout at all;
1270 */
1271 fail_tout = jiffies + TCP_RTO_MAX;
1272 if (!fail_tout)
1273 fail_tout = 1;
1274 WRITE_ONCE(subflow->fail_tout, fail_tout);
1275 tcp_send_ack(ssk);
1276
1277 mptcp_reset_tout_timer(msk, subflow->fail_tout);
1278 }
1279
subflow_check_data_avail(struct sock * ssk)1280 static bool subflow_check_data_avail(struct sock *ssk)
1281 {
1282 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1283 enum mapping_status status;
1284 struct mptcp_sock *msk;
1285 struct sk_buff *skb;
1286
1287 if (!skb_peek(&ssk->sk_receive_queue))
1288 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1289 if (subflow->data_avail)
1290 return true;
1291
1292 msk = mptcp_sk(subflow->conn);
1293 for (;;) {
1294 u64 ack_seq;
1295 u64 old_ack;
1296
1297 status = get_mapping_status(ssk, msk);
1298 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1299 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1300 status == MAPPING_BAD_CSUM))
1301 goto fallback;
1302
1303 if (status != MAPPING_OK)
1304 goto no_data;
1305
1306 skb = skb_peek(&ssk->sk_receive_queue);
1307 if (WARN_ON_ONCE(!skb))
1308 goto no_data;
1309
1310 if (unlikely(!READ_ONCE(msk->can_ack)))
1311 goto fallback;
1312
1313 old_ack = READ_ONCE(msk->ack_seq);
1314 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1315 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx\n", old_ack,
1316 ack_seq);
1317 if (unlikely(before64(ack_seq, old_ack))) {
1318 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1319 continue;
1320 }
1321
1322 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1323 break;
1324 }
1325 return true;
1326
1327 no_data:
1328 subflow_sched_work_if_closed(msk, ssk);
1329 return false;
1330
1331 fallback:
1332 if (!__mptcp_check_fallback(msk)) {
1333 /* RFC 8684 section 3.7. */
1334 if (status == MAPPING_BAD_CSUM &&
1335 (subflow->mp_join || subflow->valid_csum_seen)) {
1336 subflow->send_mp_fail = 1;
1337
1338 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1339 subflow->reset_transient = 0;
1340 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1341 goto reset;
1342 }
1343 mptcp_subflow_fail(msk, ssk);
1344 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1345 return true;
1346 }
1347
1348 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1349 /* fatal protocol error, close the socket.
1350 * subflow_error_report() will introduce the appropriate barriers
1351 */
1352 subflow->reset_transient = 0;
1353 subflow->reset_reason = MPTCP_RST_EMPTCP;
1354
1355 reset:
1356 WRITE_ONCE(ssk->sk_err, EBADMSG);
1357 tcp_set_state(ssk, TCP_CLOSE);
1358 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1359 sk_eat_skb(ssk, skb);
1360 tcp_send_active_reset(ssk, GFP_ATOMIC);
1361 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1362 return false;
1363 }
1364
1365 mptcp_do_fallback(ssk);
1366 }
1367
1368 skb = skb_peek(&ssk->sk_receive_queue);
1369 subflow->map_valid = 1;
1370 subflow->map_seq = READ_ONCE(msk->ack_seq);
1371 subflow->map_data_len = skb->len;
1372 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1373 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1374 return true;
1375 }
1376
mptcp_subflow_data_available(struct sock * sk)1377 bool mptcp_subflow_data_available(struct sock *sk)
1378 {
1379 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1380
1381 /* check if current mapping is still valid */
1382 if (subflow->map_valid &&
1383 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1384 subflow->map_valid = 0;
1385 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1386
1387 pr_debug("Done with mapping: seq=%u data_len=%u\n",
1388 subflow->map_subflow_seq,
1389 subflow->map_data_len);
1390 }
1391
1392 return subflow_check_data_avail(sk);
1393 }
1394
1395 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1396 * not the ssk one.
1397 *
1398 * In mptcp, rwin is about the mptcp-level connection data.
1399 *
1400 * Data that is still on the ssk rx queue can thus be ignored,
1401 * as far as mptcp peer is concerned that data is still inflight.
1402 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1403 */
mptcp_space(const struct sock * ssk,int * space,int * full_space)1404 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1405 {
1406 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1407 const struct sock *sk = subflow->conn;
1408
1409 *space = __mptcp_space(sk);
1410 *full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1411 }
1412
subflow_error_report(struct sock * ssk)1413 static void subflow_error_report(struct sock *ssk)
1414 {
1415 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1416
1417 /* bail early if this is a no-op, so that we avoid introducing a
1418 * problematic lockdep dependency between TCP accept queue lock
1419 * and msk socket spinlock
1420 */
1421 if (!sk->sk_socket)
1422 return;
1423
1424 mptcp_data_lock(sk);
1425 if (!sock_owned_by_user(sk))
1426 __mptcp_error_report(sk);
1427 else
1428 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
1429 mptcp_data_unlock(sk);
1430 }
1431
subflow_data_ready(struct sock * sk)1432 static void subflow_data_ready(struct sock *sk)
1433 {
1434 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1435 u16 state = 1 << inet_sk_state_load(sk);
1436 struct sock *parent = subflow->conn;
1437 struct mptcp_sock *msk;
1438
1439 trace_sk_data_ready(sk);
1440
1441 msk = mptcp_sk(parent);
1442 if (state & TCPF_LISTEN) {
1443 /* MPJ subflow are removed from accept queue before reaching here,
1444 * avoid stray wakeups
1445 */
1446 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1447 return;
1448
1449 parent->sk_data_ready(parent);
1450 return;
1451 }
1452
1453 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1454 !subflow->mp_join && !(state & TCPF_CLOSE));
1455
1456 if (mptcp_subflow_data_available(sk)) {
1457 mptcp_data_ready(parent, sk);
1458
1459 /* subflow-level lowat test are not relevant.
1460 * respect the msk-level threshold eventually mandating an immediate ack
1461 */
1462 if (mptcp_data_avail(msk) < parent->sk_rcvlowat &&
1463 (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss)
1464 inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
1465 } else if (unlikely(sk->sk_err)) {
1466 subflow_error_report(sk);
1467 }
1468 }
1469
subflow_write_space(struct sock * ssk)1470 static 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
1478 static const struct inet_connection_sock_af_ops *
subflow_default_af_ops(struct sock * sk)1479 subflow_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)
mptcpv6_handle_mapped(struct sock * sk,bool mapped)1489 void 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\n",
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
mptcp_info2sockaddr(const struct mptcp_addr_info * info,struct sockaddr_storage * addr,unsigned short family)1508 void 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
__mptcp_subflow_connect(struct sock * sk,const struct mptcp_addr_info * loc,const struct mptcp_addr_info * remote)1539 int __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\n", msk,
1593 remote_token, local_id, remote_id);
1594 subflow->remote_token = remote_token;
1595 WRITE_ONCE(subflow->remote_id, remote_id);
1596 subflow->request_join = 1;
1597 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1598 subflow->subflow_id = msk->subflow_id++;
1599 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1600
1601 sock_hold(ssk);
1602 list_add_tail(&subflow->node, &msk->conn_list);
1603 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1604 if (err && err != -EINPROGRESS)
1605 goto failed_unlink;
1606
1607 /* discard the subflow socket */
1608 mptcp_sock_graft(ssk, sk->sk_socket);
1609 iput(SOCK_INODE(sf));
1610 WRITE_ONCE(msk->allow_infinite_fallback, false);
1611 mptcp_stop_tout_timer(sk);
1612 return 0;
1613
1614 failed_unlink:
1615 list_del(&subflow->node);
1616 sock_put(mptcp_subflow_tcp_sock(subflow));
1617
1618 failed:
1619 subflow->disposable = 1;
1620 sock_release(sf);
1621
1622 err_out:
1623 /* we account subflows before the creation, and this failures will not
1624 * be caught by sk_state_change()
1625 */
1626 mptcp_pm_close_subflow(msk);
1627 return err;
1628 }
1629
mptcp_attach_cgroup(struct sock * parent,struct sock * child)1630 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1631 {
1632 #ifdef CONFIG_SOCK_CGROUP_DATA
1633 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1634 *child_skcd = &child->sk_cgrp_data;
1635
1636 /* only the additional subflows created by kworkers have to be modified */
1637 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1638 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1639 #ifdef CONFIG_MEMCG
1640 struct mem_cgroup *memcg = parent->sk_memcg;
1641
1642 mem_cgroup_sk_free(child);
1643 if (memcg && css_tryget(&memcg->css))
1644 child->sk_memcg = memcg;
1645 #endif /* CONFIG_MEMCG */
1646
1647 cgroup_sk_free(child_skcd);
1648 *child_skcd = *parent_skcd;
1649 cgroup_sk_clone(child_skcd);
1650 }
1651 #endif /* CONFIG_SOCK_CGROUP_DATA */
1652 }
1653
mptcp_subflow_ops_override(struct sock * ssk)1654 static void mptcp_subflow_ops_override(struct sock *ssk)
1655 {
1656 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1657 if (ssk->sk_prot == &tcpv6_prot)
1658 ssk->sk_prot = &tcpv6_prot_override;
1659 else
1660 #endif
1661 ssk->sk_prot = &tcp_prot_override;
1662 }
1663
mptcp_subflow_ops_undo_override(struct sock * ssk)1664 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1665 {
1666 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1667 if (ssk->sk_prot == &tcpv6_prot_override)
1668 ssk->sk_prot = &tcpv6_prot;
1669 else
1670 #endif
1671 ssk->sk_prot = &tcp_prot;
1672 }
1673
mptcp_subflow_create_socket(struct sock * sk,unsigned short family,struct socket ** new_sock)1674 int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1675 struct socket **new_sock)
1676 {
1677 struct mptcp_subflow_context *subflow;
1678 struct net *net = sock_net(sk);
1679 struct socket *sf;
1680 int err;
1681
1682 /* un-accepted server sockets can reach here - on bad configuration
1683 * bail early to avoid greater trouble later
1684 */
1685 if (unlikely(!sk->sk_socket))
1686 return -EINVAL;
1687
1688 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
1689 if (err)
1690 return err;
1691
1692 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
1693
1694 err = security_mptcp_add_subflow(sk, sf->sk);
1695 if (err)
1696 goto release_ssk;
1697
1698 /* the newly created socket has to be in the same cgroup as its parent */
1699 mptcp_attach_cgroup(sk, sf->sk);
1700
1701 /* kernel sockets do not by default acquire net ref, but TCP timer
1702 * needs it.
1703 * Update ns_tracker to current stack trace and refcounted tracker.
1704 */
1705 __netns_tracker_free(net, &sf->sk->ns_tracker, false);
1706 sf->sk->sk_net_refcnt = 1;
1707 get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL);
1708 sock_inuse_add(net, 1);
1709 err = tcp_set_ulp(sf->sk, "mptcp");
1710
1711 release_ssk:
1712 release_sock(sf->sk);
1713
1714 if (err) {
1715 sock_release(sf);
1716 return err;
1717 }
1718
1719 /* the newly created socket really belongs to the owning MPTCP master
1720 * socket, even if for additional subflows the allocation is performed
1721 * by a kernel workqueue. Adjust inode references, so that the
1722 * procfs/diag interfaces really show this one belonging to the correct
1723 * user.
1724 */
1725 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1726 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1727 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1728
1729 subflow = mptcp_subflow_ctx(sf->sk);
1730 pr_debug("subflow=%p\n", subflow);
1731
1732 *new_sock = sf;
1733 sock_hold(sk);
1734 subflow->conn = sk;
1735 mptcp_subflow_ops_override(sf->sk);
1736
1737 return 0;
1738 }
1739
subflow_create_ctx(struct sock * sk,gfp_t priority)1740 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1741 gfp_t priority)
1742 {
1743 struct inet_connection_sock *icsk = inet_csk(sk);
1744 struct mptcp_subflow_context *ctx;
1745
1746 ctx = kzalloc(sizeof(*ctx), priority);
1747 if (!ctx)
1748 return NULL;
1749
1750 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1751 INIT_LIST_HEAD(&ctx->node);
1752 INIT_LIST_HEAD(&ctx->delegated_node);
1753
1754 pr_debug("subflow=%p\n", ctx);
1755
1756 ctx->tcp_sock = sk;
1757 WRITE_ONCE(ctx->local_id, -1);
1758
1759 return ctx;
1760 }
1761
__subflow_state_change(struct sock * sk)1762 static void __subflow_state_change(struct sock *sk)
1763 {
1764 struct socket_wq *wq;
1765
1766 rcu_read_lock();
1767 wq = rcu_dereference(sk->sk_wq);
1768 if (skwq_has_sleeper(wq))
1769 wake_up_interruptible_all(&wq->wait);
1770 rcu_read_unlock();
1771 }
1772
subflow_is_done(const struct sock * sk)1773 static bool subflow_is_done(const struct sock *sk)
1774 {
1775 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1776 }
1777
subflow_state_change(struct sock * sk)1778 static void subflow_state_change(struct sock *sk)
1779 {
1780 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1781 struct sock *parent = subflow->conn;
1782 struct mptcp_sock *msk;
1783
1784 __subflow_state_change(sk);
1785
1786 msk = mptcp_sk(parent);
1787 if (subflow_simultaneous_connect(sk)) {
1788 mptcp_do_fallback(sk);
1789 pr_fallback(msk);
1790 subflow->conn_finished = 1;
1791 mptcp_propagate_state(parent, sk, subflow, NULL);
1792 }
1793
1794 /* as recvmsg() does not acquire the subflow socket for ssk selection
1795 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1796 * the data available machinery here.
1797 */
1798 if (mptcp_subflow_data_available(sk))
1799 mptcp_data_ready(parent, sk);
1800 else if (unlikely(sk->sk_err))
1801 subflow_error_report(sk);
1802
1803 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1804
1805 /* when the fallback subflow closes the rx side, trigger a 'dummy'
1806 * ingress data fin, so that the msk state will follow along
1807 */
1808 if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
1809 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
1810 mptcp_schedule_work(parent);
1811 }
1812
mptcp_subflow_queue_clean(struct sock * listener_sk,struct sock * listener_ssk)1813 void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1814 {
1815 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
1816 struct request_sock *req, *head, *tail;
1817 struct mptcp_subflow_context *subflow;
1818 struct sock *sk, *ssk;
1819
1820 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
1821 * Splice the req list, so that accept() can not reach the pending ssk after
1822 * the listener socket is released below.
1823 */
1824 spin_lock_bh(&queue->rskq_lock);
1825 head = queue->rskq_accept_head;
1826 tail = queue->rskq_accept_tail;
1827 queue->rskq_accept_head = NULL;
1828 queue->rskq_accept_tail = NULL;
1829 spin_unlock_bh(&queue->rskq_lock);
1830
1831 if (!head)
1832 return;
1833
1834 /* can't acquire the msk socket lock under the subflow one,
1835 * or will cause ABBA deadlock
1836 */
1837 release_sock(listener_ssk);
1838
1839 for (req = head; req; req = req->dl_next) {
1840 ssk = req->sk;
1841 if (!sk_is_mptcp(ssk))
1842 continue;
1843
1844 subflow = mptcp_subflow_ctx(ssk);
1845 if (!subflow || !subflow->conn)
1846 continue;
1847
1848 sk = subflow->conn;
1849 sock_hold(sk);
1850
1851 lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1852 __mptcp_unaccepted_force_close(sk);
1853 release_sock(sk);
1854
1855 /* lockdep will report a false positive ABBA deadlock
1856 * between cancel_work_sync and the listener socket.
1857 * The involved locks belong to different sockets WRT
1858 * the existing AB chain.
1859 * Using a per socket key is problematic as key
1860 * deregistration requires process context and must be
1861 * performed at socket disposal time, in atomic
1862 * context.
1863 * Just tell lockdep to consider the listener socket
1864 * released here.
1865 */
1866 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1867 mptcp_cancel_work(sk);
1868 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
1869
1870 sock_put(sk);
1871 }
1872
1873 /* we are still under the listener msk socket lock */
1874 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
1875
1876 /* restore the listener queue, to let the TCP code clean it up */
1877 spin_lock_bh(&queue->rskq_lock);
1878 WARN_ON_ONCE(queue->rskq_accept_head);
1879 queue->rskq_accept_head = head;
1880 queue->rskq_accept_tail = tail;
1881 spin_unlock_bh(&queue->rskq_lock);
1882 }
1883
subflow_ulp_init(struct sock * sk)1884 static int subflow_ulp_init(struct sock *sk)
1885 {
1886 struct inet_connection_sock *icsk = inet_csk(sk);
1887 struct mptcp_subflow_context *ctx;
1888 struct tcp_sock *tp = tcp_sk(sk);
1889 int err = 0;
1890
1891 /* disallow attaching ULP to a socket unless it has been
1892 * created with sock_create_kern()
1893 */
1894 if (!sk->sk_kern_sock) {
1895 err = -EOPNOTSUPP;
1896 goto out;
1897 }
1898
1899 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1900 if (!ctx) {
1901 err = -ENOMEM;
1902 goto out;
1903 }
1904
1905 pr_debug("subflow=%p, family=%d\n", ctx, sk->sk_family);
1906
1907 tp->is_mptcp = 1;
1908 ctx->icsk_af_ops = icsk->icsk_af_ops;
1909 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1910 ctx->tcp_state_change = sk->sk_state_change;
1911 ctx->tcp_error_report = sk->sk_error_report;
1912
1913 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1914 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1915
1916 sk->sk_data_ready = subflow_data_ready;
1917 sk->sk_write_space = subflow_write_space;
1918 sk->sk_state_change = subflow_state_change;
1919 sk->sk_error_report = subflow_error_report;
1920 out:
1921 return err;
1922 }
1923
subflow_ulp_release(struct sock * ssk)1924 static void subflow_ulp_release(struct sock *ssk)
1925 {
1926 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1927 bool release = true;
1928 struct sock *sk;
1929
1930 if (!ctx)
1931 return;
1932
1933 sk = ctx->conn;
1934 if (sk) {
1935 /* if the msk has been orphaned, keep the ctx
1936 * alive, will be freed by __mptcp_close_ssk(),
1937 * when the subflow is still unaccepted
1938 */
1939 release = ctx->disposable || list_empty(&ctx->node);
1940
1941 /* inet_child_forget() does not call sk_state_change(),
1942 * explicitly trigger the socket close machinery
1943 */
1944 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
1945 &mptcp_sk(sk)->flags))
1946 mptcp_schedule_work(sk);
1947 sock_put(sk);
1948 }
1949
1950 mptcp_subflow_ops_undo_override(ssk);
1951 if (release)
1952 kfree_rcu(ctx, rcu);
1953 }
1954
subflow_ulp_clone(const struct request_sock * req,struct sock * newsk,const gfp_t priority)1955 static void subflow_ulp_clone(const struct request_sock *req,
1956 struct sock *newsk,
1957 const gfp_t priority)
1958 {
1959 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1960 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1961 struct mptcp_subflow_context *new_ctx;
1962
1963 if (!tcp_rsk(req)->is_mptcp ||
1964 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1965 subflow_ulp_fallback(newsk, old_ctx);
1966 return;
1967 }
1968
1969 new_ctx = subflow_create_ctx(newsk, priority);
1970 if (!new_ctx) {
1971 subflow_ulp_fallback(newsk, old_ctx);
1972 return;
1973 }
1974
1975 new_ctx->conn_finished = 1;
1976 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1977 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1978 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1979 new_ctx->rel_write_seq = 1;
1980 new_ctx->tcp_sock = newsk;
1981
1982 if (subflow_req->mp_capable) {
1983 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1984 * is fully established only after we receive the remote key
1985 */
1986 new_ctx->mp_capable = 1;
1987 new_ctx->local_key = subflow_req->local_key;
1988 new_ctx->token = subflow_req->token;
1989 new_ctx->ssn_offset = subflow_req->ssn_offset;
1990 new_ctx->idsn = subflow_req->idsn;
1991
1992 /* this is the first subflow, id is always 0 */
1993 subflow_set_local_id(new_ctx, 0);
1994 } else if (subflow_req->mp_join) {
1995 new_ctx->ssn_offset = subflow_req->ssn_offset;
1996 new_ctx->mp_join = 1;
1997 new_ctx->fully_established = 1;
1998 new_ctx->remote_key_valid = 1;
1999 new_ctx->backup = subflow_req->backup;
2000 new_ctx->request_bkup = subflow_req->request_bkup;
2001 WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id);
2002 new_ctx->token = subflow_req->token;
2003 new_ctx->thmac = subflow_req->thmac;
2004
2005 /* the subflow req id is valid, fetched via subflow_check_req()
2006 * and subflow_token_join_request()
2007 */
2008 subflow_set_local_id(new_ctx, subflow_req->local_id);
2009 }
2010 }
2011
tcp_release_cb_override(struct sock * ssk)2012 static void tcp_release_cb_override(struct sock *ssk)
2013 {
2014 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
2015 long status;
2016
2017 /* process and clear all the pending actions, but leave the subflow into
2018 * the napi queue. To respect locking, only the same CPU that originated
2019 * the action can touch the list. mptcp_napi_poll will take care of it.
2020 */
2021 status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0);
2022 if (status)
2023 mptcp_subflow_process_delegated(ssk, status);
2024
2025 tcp_release_cb(ssk);
2026 }
2027
tcp_abort_override(struct sock * ssk,int err)2028 static int tcp_abort_override(struct sock *ssk, int err)
2029 {
2030 /* closing a listener subflow requires a great deal of care.
2031 * keep it simple and just prevent such operation
2032 */
2033 if (inet_sk_state_load(ssk) == TCP_LISTEN)
2034 return -EINVAL;
2035
2036 return tcp_abort(ssk, err);
2037 }
2038
2039 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
2040 .name = "mptcp",
2041 .owner = THIS_MODULE,
2042 .init = subflow_ulp_init,
2043 .release = subflow_ulp_release,
2044 .clone = subflow_ulp_clone,
2045 };
2046
subflow_ops_init(struct request_sock_ops * subflow_ops)2047 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
2048 {
2049 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
2050
2051 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
2052 subflow_ops->obj_size, 0,
2053 SLAB_ACCOUNT |
2054 SLAB_TYPESAFE_BY_RCU,
2055 NULL);
2056 if (!subflow_ops->slab)
2057 return -ENOMEM;
2058
2059 return 0;
2060 }
2061
mptcp_subflow_init(void)2062 void __init mptcp_subflow_init(void)
2063 {
2064 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
2065 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
2066 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
2067
2068 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
2069 panic("MPTCP: failed to init subflow v4 request sock ops\n");
2070
2071 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
2072 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
2073 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
2074
2075 subflow_specific = ipv4_specific;
2076 subflow_specific.conn_request = subflow_v4_conn_request;
2077 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
2078 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
2079 subflow_specific.rebuild_header = subflow_rebuild_header;
2080
2081 tcp_prot_override = tcp_prot;
2082 tcp_prot_override.release_cb = tcp_release_cb_override;
2083 tcp_prot_override.diag_destroy = tcp_abort_override;
2084
2085 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
2086 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock
2087 * structures for v4 and v6 have the same size. It should not changed in
2088 * the future but better to make sure to be warned if it is no longer
2089 * the case.
2090 */
2091 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
2092
2093 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
2094 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
2095 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
2096
2097 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
2098 panic("MPTCP: failed to init subflow v6 request sock ops\n");
2099
2100 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
2101 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
2102 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
2103
2104 subflow_v6_specific = ipv6_specific;
2105 subflow_v6_specific.conn_request = subflow_v6_conn_request;
2106 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
2107 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
2108 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
2109
2110 subflow_v6m_specific = subflow_v6_specific;
2111 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
2112 subflow_v6m_specific.send_check = ipv4_specific.send_check;
2113 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
2114 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
2115 subflow_v6m_specific.net_frag_header_len = 0;
2116 subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
2117
2118 tcpv6_prot_override = tcpv6_prot;
2119 tcpv6_prot_override.release_cb = tcp_release_cb_override;
2120 tcpv6_prot_override.diag_destroy = tcp_abort_override;
2121 #endif
2122
2123 mptcp_diag_subflow_init(&subflow_ulp_ops);
2124
2125 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
2126 panic("MPTCP: failed to register subflows to ULP\n");
2127 }
2128