1 // SPDX-License-Identifier: GPL-2.0
4 * Copyright (c) 2017 - 2019, Intel Corporation.
7 #define pr_fmt(fmt) "MPTCP: " fmt
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>
15 #include <net/inet_common.h>
16 #include <net/inet_hashtables.h>
17 #include <net/protocol.h>
19 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
20 #include <net/ip6_route.h>
21 #include <net/transp_v6.h>
23 #include <net/mptcp.h>
24 #include <uapi/linux/mptcp.h>
28 #include <trace/events/mptcp.h>
30 static void mptcp_subflow_ops_undo_override(struct sock *ssk);
32 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
33 enum linux_mptcp_mib_field field)
35 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
38 static void subflow_req_destructor(struct request_sock *req)
40 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
42 pr_debug("subflow_req=%p", subflow_req);
45 sock_put((struct sock *)subflow_req->msk);
47 mptcp_token_destroy_request(req);
50 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
55 put_unaligned_be32(nonce1, &msg[0]);
56 put_unaligned_be32(nonce2, &msg[4]);
58 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
61 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
63 return mptcp_is_fully_established((void *)msk) &&
64 ((mptcp_pm_is_userspace(msk) &&
65 mptcp_userspace_pm_active(msk)) ||
66 READ_ONCE(msk->pm.accept_subflow));
69 /* validate received token and create truncated hmac and nonce for SYN-ACK */
70 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
72 struct mptcp_sock *msk = subflow_req->msk;
73 u8 hmac[SHA256_DIGEST_SIZE];
75 get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
77 subflow_generate_hmac(msk->local_key, msk->remote_key,
78 subflow_req->local_nonce,
79 subflow_req->remote_nonce, hmac);
81 subflow_req->thmac = get_unaligned_be64(hmac);
84 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
86 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
87 struct mptcp_sock *msk;
90 msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
92 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
96 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
98 sock_put((struct sock *)msk);
101 subflow_req->local_id = local_id;
106 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
108 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
110 subflow_req->mp_capable = 0;
111 subflow_req->mp_join = 0;
112 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
113 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
114 subflow_req->msk = NULL;
115 mptcp_token_init_request(req);
118 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
120 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
123 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
125 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
128 memset(mpext, 0, sizeof(*mpext));
129 mpext->reset_reason = reason;
133 /* Init mptcp request socket.
135 * Returns an error code if a JOIN has failed and a TCP reset
138 static int subflow_check_req(struct request_sock *req,
139 const struct sock *sk_listener,
142 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
143 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
144 struct mptcp_options_received mp_opt;
145 bool opt_mp_capable, opt_mp_join;
147 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
149 #ifdef CONFIG_TCP_MD5SIG
150 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
153 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
157 mptcp_get_options(skb, &mp_opt);
159 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
160 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
161 if (opt_mp_capable) {
162 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
166 } else if (opt_mp_join) {
167 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
170 if (opt_mp_capable && listener->request_mptcp) {
171 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
173 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
176 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
177 } while (subflow_req->local_key == 0);
179 if (unlikely(req->syncookie)) {
180 mptcp_crypto_key_sha(subflow_req->local_key,
183 if (mptcp_token_exists(subflow_req->token)) {
186 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
188 subflow_req->mp_capable = 1;
193 err = mptcp_token_new_request(req);
195 subflow_req->mp_capable = 1;
196 else if (retries-- > 0)
199 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
201 } else if (opt_mp_join && listener->request_mptcp) {
202 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
203 subflow_req->mp_join = 1;
204 subflow_req->backup = mp_opt.backup;
205 subflow_req->remote_id = mp_opt.join_id;
206 subflow_req->token = mp_opt.token;
207 subflow_req->remote_nonce = mp_opt.nonce;
208 subflow_req->msk = subflow_token_join_request(req);
210 /* Can't fall back to TCP in this case. */
211 if (!subflow_req->msk) {
212 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
216 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
217 pr_debug("syn inet_sport=%d %d",
218 ntohs(inet_sk(sk_listener)->inet_sport),
219 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
220 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
221 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
224 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
227 subflow_req_create_thmac(subflow_req);
229 if (unlikely(req->syncookie)) {
230 if (mptcp_can_accept_new_subflow(subflow_req->msk))
231 subflow_init_req_cookie_join_save(subflow_req, skb);
236 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
237 subflow_req->remote_nonce, subflow_req->msk);
243 int mptcp_subflow_init_cookie_req(struct request_sock *req,
244 const struct sock *sk_listener,
247 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
248 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
249 struct mptcp_options_received mp_opt;
250 bool opt_mp_capable, opt_mp_join;
253 subflow_init_req(req, sk_listener);
254 mptcp_get_options(skb, &mp_opt);
256 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
257 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
258 if (opt_mp_capable && opt_mp_join)
261 if (opt_mp_capable && listener->request_mptcp) {
262 if (mp_opt.sndr_key == 0)
265 subflow_req->local_key = mp_opt.rcvr_key;
266 err = mptcp_token_new_request(req);
270 subflow_req->mp_capable = 1;
271 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
272 } else if (opt_mp_join && listener->request_mptcp) {
273 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
276 subflow_req->mp_join = 1;
277 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
282 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
284 static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
287 struct request_sock *req)
289 struct dst_entry *dst;
292 tcp_rsk(req)->is_mptcp = 1;
293 subflow_init_req(req, sk);
295 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
299 err = subflow_check_req(req, sk, skb);
305 tcp_request_sock_ops.send_reset(sk, skb);
309 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
310 static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
313 struct request_sock *req)
315 struct dst_entry *dst;
318 tcp_rsk(req)->is_mptcp = 1;
319 subflow_init_req(req, sk);
321 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
325 err = subflow_check_req(req, sk, skb);
331 tcp6_request_sock_ops.send_reset(sk, skb);
336 /* validate received truncated hmac and create hmac for third ACK */
337 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
339 u8 hmac[SHA256_DIGEST_SIZE];
342 subflow_generate_hmac(subflow->remote_key, subflow->local_key,
343 subflow->remote_nonce, subflow->local_nonce,
346 thmac = get_unaligned_be64(hmac);
347 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
348 subflow, subflow->token, thmac, subflow->thmac);
350 return thmac == subflow->thmac;
353 void mptcp_subflow_reset(struct sock *ssk)
355 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
356 struct sock *sk = subflow->conn;
358 /* mptcp_mp_fail_no_response() can reach here on an already closed
361 if (ssk->sk_state == TCP_CLOSE)
364 /* must hold: tcp_done() could drop last reference on parent */
367 tcp_send_active_reset(ssk, GFP_ATOMIC);
369 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
370 mptcp_schedule_work(sk);
375 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
377 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
380 void __mptcp_set_connected(struct sock *sk)
382 if (sk->sk_state == TCP_SYN_SENT) {
383 inet_sk_state_store(sk, TCP_ESTABLISHED);
384 sk->sk_state_change(sk);
388 static void mptcp_set_connected(struct sock *sk)
391 if (!sock_owned_by_user(sk))
392 __mptcp_set_connected(sk);
394 __set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->cb_flags);
395 mptcp_data_unlock(sk);
398 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
400 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
401 struct mptcp_options_received mp_opt;
402 struct sock *parent = subflow->conn;
404 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
406 /* be sure no special action on any packet other than syn-ack */
407 if (subflow->conn_finished)
410 mptcp_propagate_sndbuf(parent, sk);
411 subflow->rel_write_seq = 1;
412 subflow->conn_finished = 1;
413 subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
414 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
416 mptcp_get_options(skb, &mp_opt);
417 if (subflow->request_mptcp) {
418 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
419 MPTCP_INC_STATS(sock_net(sk),
420 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
421 mptcp_do_fallback(sk);
422 pr_fallback(mptcp_sk(subflow->conn));
426 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
427 WRITE_ONCE(mptcp_sk(parent)->csum_enabled, true);
428 if (mp_opt.deny_join_id0)
429 WRITE_ONCE(mptcp_sk(parent)->pm.remote_deny_join_id0, true);
430 subflow->mp_capable = 1;
431 subflow->can_ack = 1;
432 subflow->remote_key = mp_opt.sndr_key;
433 pr_debug("subflow=%p, remote_key=%llu", subflow,
434 subflow->remote_key);
435 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
436 mptcp_finish_connect(sk);
437 mptcp_set_connected(parent);
438 } else if (subflow->request_join) {
439 u8 hmac[SHA256_DIGEST_SIZE];
441 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) {
442 subflow->reset_reason = MPTCP_RST_EMPTCP;
446 subflow->backup = mp_opt.backup;
447 subflow->thmac = mp_opt.thmac;
448 subflow->remote_nonce = mp_opt.nonce;
449 subflow->remote_id = mp_opt.join_id;
450 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
451 subflow, subflow->thmac, subflow->remote_nonce,
454 if (!subflow_thmac_valid(subflow)) {
455 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
456 subflow->reset_reason = MPTCP_RST_EMPTCP;
460 if (!mptcp_finish_join(sk))
463 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
464 subflow->local_nonce,
465 subflow->remote_nonce,
467 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
469 subflow->mp_join = 1;
470 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
472 if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
473 pr_debug("synack inet_dport=%d %d",
474 ntohs(inet_sk(sk)->inet_dport),
475 ntohs(inet_sk(parent)->inet_dport));
476 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
478 } else if (mptcp_check_fallback(sk)) {
480 mptcp_rcv_space_init(mptcp_sk(parent), sk);
481 mptcp_set_connected(parent);
486 subflow->reset_transient = 0;
487 mptcp_subflow_reset(sk);
490 static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
492 subflow->local_id = local_id;
493 subflow->local_id_valid = 1;
496 static int subflow_chk_local_id(struct sock *sk)
498 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
499 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
502 if (likely(subflow->local_id_valid))
505 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
509 subflow_set_local_id(subflow, err);
513 static int subflow_rebuild_header(struct sock *sk)
515 int err = subflow_chk_local_id(sk);
517 if (unlikely(err < 0))
520 return inet_sk_rebuild_header(sk);
523 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
524 static int subflow_v6_rebuild_header(struct sock *sk)
526 int err = subflow_chk_local_id(sk);
528 if (unlikely(err < 0))
531 return inet6_sk_rebuild_header(sk);
535 static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
536 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
538 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
540 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
542 pr_debug("subflow=%p", subflow);
544 /* Never answer to SYNs sent to broadcast or multicast */
545 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
548 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
549 &subflow_request_sock_ipv4_ops,
556 static void subflow_v4_req_destructor(struct request_sock *req)
558 subflow_req_destructor(req);
559 tcp_request_sock_ops.destructor(req);
562 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
563 static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
564 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
565 static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
566 static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
567 static struct proto tcpv6_prot_override __ro_after_init;
569 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
571 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
573 pr_debug("subflow=%p", subflow);
575 if (skb->protocol == htons(ETH_P_IP))
576 return subflow_v4_conn_request(sk, skb);
578 if (!ipv6_unicast_destination(skb))
581 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
582 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
586 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
587 &subflow_request_sock_ipv6_ops, sk, skb);
591 return 0; /* don't send reset */
594 static void subflow_v6_req_destructor(struct request_sock *req)
596 subflow_req_destructor(req);
597 tcp6_request_sock_ops.destructor(req);
601 struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
602 struct sock *sk_listener,
603 bool attach_listener)
605 if (ops->family == AF_INET)
606 ops = &mptcp_subflow_v4_request_sock_ops;
607 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
608 else if (ops->family == AF_INET6)
609 ops = &mptcp_subflow_v6_request_sock_ops;
612 return inet_reqsk_alloc(ops, sk_listener, attach_listener);
614 EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
616 /* validate hmac received in third ACK */
617 static bool subflow_hmac_valid(const struct request_sock *req,
618 const struct mptcp_options_received *mp_opt)
620 const struct mptcp_subflow_request_sock *subflow_req;
621 u8 hmac[SHA256_DIGEST_SIZE];
622 struct mptcp_sock *msk;
624 subflow_req = mptcp_subflow_rsk(req);
625 msk = subflow_req->msk;
629 subflow_generate_hmac(msk->remote_key, msk->local_key,
630 subflow_req->remote_nonce,
631 subflow_req->local_nonce, hmac);
633 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
636 static void subflow_ulp_fallback(struct sock *sk,
637 struct mptcp_subflow_context *old_ctx)
639 struct inet_connection_sock *icsk = inet_csk(sk);
641 mptcp_subflow_tcp_fallback(sk, old_ctx);
642 icsk->icsk_ulp_ops = NULL;
643 rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
644 tcp_sk(sk)->is_mptcp = 0;
646 mptcp_subflow_ops_undo_override(sk);
649 void mptcp_subflow_drop_ctx(struct sock *ssk)
651 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
656 list_del(&mptcp_subflow_ctx(ssk)->node);
657 if (inet_csk(ssk)->icsk_ulp_ops) {
658 subflow_ulp_fallback(ssk, ctx);
666 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
667 struct mptcp_options_received *mp_opt)
669 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
671 subflow->remote_key = mp_opt->sndr_key;
672 subflow->fully_established = 1;
673 subflow->can_ack = 1;
674 WRITE_ONCE(msk->fully_established, true);
677 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
679 struct request_sock *req,
680 struct dst_entry *dst,
681 struct request_sock *req_unhash,
684 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
685 struct mptcp_subflow_request_sock *subflow_req;
686 struct mptcp_options_received mp_opt;
687 bool fallback, fallback_is_fatal;
688 struct mptcp_sock *owner;
691 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
693 /* After child creation we must look for MPC even when options
696 mp_opt.suboptions = 0;
698 /* hopefully temporary handling for MP_JOIN+syncookie */
699 subflow_req = mptcp_subflow_rsk(req);
700 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
701 fallback = !tcp_rsk(req)->is_mptcp;
705 /* if the sk is MP_CAPABLE, we try to fetch the client key */
706 if (subflow_req->mp_capable) {
707 /* we can receive and accept an in-window, out-of-order pkt,
708 * which may not carry the MP_CAPABLE opt even on mptcp enabled
709 * paths: always try to extract the peer key, and fallback
710 * for packets missing it.
711 * Even OoO DSS packets coming legitly after dropped or
712 * reordered MPC will cause fallback, but we don't have other
715 mptcp_get_options(skb, &mp_opt);
716 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC))
719 } else if (subflow_req->mp_join) {
720 mptcp_get_options(skb, &mp_opt);
721 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||
722 !subflow_hmac_valid(req, &mp_opt) ||
723 !mptcp_can_accept_new_subflow(subflow_req->msk)) {
724 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
730 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
731 req_unhash, own_req);
733 if (child && *own_req) {
734 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
736 tcp_rsk(req)->drop_req = false;
738 /* we need to fallback on ctx allocation failure and on pre-reqs
739 * checking above. In the latter scenario we additionally need
740 * to reset the context to non MPTCP status.
742 if (!ctx || fallback) {
743 if (fallback_is_fatal) {
744 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
750 /* ssk inherits options of listener sk */
751 ctx->setsockopt_seq = listener->setsockopt_seq;
753 if (ctx->mp_capable) {
754 ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req);
758 owner = mptcp_sk(ctx->conn);
759 mptcp_pm_new_connection(owner, child, 1);
761 /* with OoO packets we can reach here without ingress
764 if (mp_opt.suboptions & OPTIONS_MPTCP_MPC) {
765 mptcp_subflow_fully_established(ctx, &mp_opt);
766 mptcp_pm_fully_established(owner, child, GFP_ATOMIC);
767 ctx->pm_notified = 1;
769 } else if (ctx->mp_join) {
770 owner = subflow_req->msk;
772 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
776 /* move the msk reference ownership to the subflow */
777 subflow_req->msk = NULL;
778 ctx->conn = (struct sock *)owner;
780 if (subflow_use_different_sport(owner, sk)) {
781 pr_debug("ack inet_sport=%d %d",
782 ntohs(inet_sk(sk)->inet_sport),
783 ntohs(inet_sk((struct sock *)owner)->inet_sport));
784 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
785 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
788 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
791 if (!mptcp_finish_join(child))
794 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
795 tcp_rsk(req)->drop_req = true;
799 /* check for expected invariant - should never trigger, just help
800 * catching eariler subtle bugs
802 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
803 (!mptcp_subflow_ctx(child) ||
804 !mptcp_subflow_ctx(child)->conn));
808 mptcp_subflow_drop_ctx(child);
809 tcp_rsk(req)->drop_req = true;
810 inet_csk_prepare_for_destroy_sock(child);
812 req->rsk_ops->send_reset(sk, skb);
814 /* The last child reference will be released by the caller */
818 mptcp_subflow_drop_ctx(child);
822 static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
823 static struct proto tcp_prot_override __ro_after_init;
825 enum mapping_status {
834 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
836 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
837 ssn, subflow->map_subflow_seq, subflow->map_data_len);
840 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
842 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
843 unsigned int skb_consumed;
845 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
846 if (WARN_ON_ONCE(skb_consumed >= skb->len))
849 return skb->len - skb_consumed <= subflow->map_data_len -
850 mptcp_subflow_get_map_offset(subflow);
853 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
855 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
856 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
858 if (unlikely(before(ssn, subflow->map_subflow_seq))) {
859 /* Mapping covers data later in the subflow stream,
860 * currently unsupported.
862 dbg_bad_map(subflow, ssn);
865 if (unlikely(!before(ssn, subflow->map_subflow_seq +
866 subflow->map_data_len))) {
867 /* Mapping does covers past subflow data, invalid */
868 dbg_bad_map(subflow, ssn);
874 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
877 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
878 u32 offset, seq, delta;
885 /* mapping already validated on previous traversal */
886 if (subflow->map_csum_len == subflow->map_data_len)
889 /* traverse the receive queue, ensuring it contains a full
890 * DSS mapping and accumulating the related csum.
891 * Preserve the accoumlate csum across multiple calls, to compute
894 delta = subflow->map_data_len - subflow->map_csum_len;
896 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
897 offset = seq - TCP_SKB_CB(skb)->seq;
899 /* if the current skb has not been accounted yet, csum its contents
900 * up to the amount covered by the current DSS
902 if (offset < skb->len) {
905 len = min(skb->len - offset, delta);
906 csum = skb_checksum(skb, offset, len, 0);
907 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
908 subflow->map_csum_len);
911 subflow->map_csum_len += len;
916 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
917 /* if this subflow is closed, the partial mapping
918 * will be never completed; flush the pending skbs, so
919 * that subflow_sched_work_if_closed() can kick in
921 if (unlikely(ssk->sk_state == TCP_CLOSE))
922 while ((skb = skb_peek(&ssk->sk_receive_queue)))
923 sk_eat_skb(ssk, skb);
925 /* not enough data to validate the csum */
926 return MAPPING_EMPTY;
929 /* the DSS mapping for next skbs will be validated later,
930 * when a get_mapping_status call will process such skb
935 /* note that 'map_data_len' accounts only for the carried data, does
936 * not include the eventual seq increment due to the data fin,
937 * while the pseudo header requires the original DSS data len,
940 csum = __mptcp_make_csum(subflow->map_seq,
941 subflow->map_subflow_seq,
942 subflow->map_data_len + subflow->map_data_fin,
943 subflow->map_data_csum);
944 if (unlikely(csum)) {
945 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
946 return MAPPING_BAD_CSUM;
949 subflow->valid_csum_seen = 1;
953 static enum mapping_status get_mapping_status(struct sock *ssk,
954 struct mptcp_sock *msk)
956 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
957 bool csum_reqd = READ_ONCE(msk->csum_enabled);
958 struct mptcp_ext *mpext;
963 skb = skb_peek(&ssk->sk_receive_queue);
965 return MAPPING_EMPTY;
967 if (mptcp_check_fallback(ssk))
968 return MAPPING_DUMMY;
970 mpext = mptcp_get_ext(skb);
971 if (!mpext || !mpext->use_map) {
972 if (!subflow->map_valid && !skb->len) {
973 /* the TCP stack deliver 0 len FIN pkt to the receive
974 * queue, that is the only 0len pkts ever expected here,
975 * and we can admit no mapping only for 0 len pkts
977 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
978 WARN_ONCE(1, "0len seq %d:%d flags %x",
979 TCP_SKB_CB(skb)->seq,
980 TCP_SKB_CB(skb)->end_seq,
981 TCP_SKB_CB(skb)->tcp_flags);
982 sk_eat_skb(ssk, skb);
983 return MAPPING_EMPTY;
986 if (!subflow->map_valid)
987 return MAPPING_INVALID;
992 trace_get_mapping_status(mpext);
994 data_len = mpext->data_len;
996 pr_debug("infinite mapping received");
997 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
998 subflow->map_data_len = 0;
999 return MAPPING_INVALID;
1002 if (mpext->data_fin == 1) {
1003 if (data_len == 1) {
1004 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
1006 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
1007 if (subflow->map_valid) {
1008 /* A DATA_FIN might arrive in a DSS
1009 * option before the previous mapping
1010 * has been fully consumed. Continue
1011 * handling the existing mapping.
1013 skb_ext_del(skb, SKB_EXT_MPTCP);
1017 mptcp_schedule_work((struct sock *)msk);
1019 return MAPPING_DATA_FIN;
1022 u64 data_fin_seq = mpext->data_seq + data_len - 1;
1024 /* If mpext->data_seq is a 32-bit value, data_fin_seq
1025 * must also be limited to 32 bits.
1028 data_fin_seq &= GENMASK_ULL(31, 0);
1030 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1031 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
1032 data_fin_seq, mpext->dsn64);
1035 /* Adjust for DATA_FIN using 1 byte of sequence space */
1039 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1040 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1042 if (subflow->map_valid) {
1043 /* Allow replacing only with an identical map */
1044 if (subflow->map_seq == map_seq &&
1045 subflow->map_subflow_seq == mpext->subflow_seq &&
1046 subflow->map_data_len == data_len &&
1047 subflow->map_csum_reqd == mpext->csum_reqd) {
1048 skb_ext_del(skb, SKB_EXT_MPTCP);
1052 /* If this skb data are fully covered by the current mapping,
1053 * the new map would need caching, which is not supported
1055 if (skb_is_fully_mapped(ssk, skb)) {
1056 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1057 return MAPPING_INVALID;
1060 /* will validate the next map after consuming the current one */
1064 subflow->map_seq = map_seq;
1065 subflow->map_subflow_seq = mpext->subflow_seq;
1066 subflow->map_data_len = data_len;
1067 subflow->map_valid = 1;
1068 subflow->map_data_fin = mpext->data_fin;
1069 subflow->mpc_map = mpext->mpc_map;
1070 subflow->map_csum_reqd = mpext->csum_reqd;
1071 subflow->map_csum_len = 0;
1072 subflow->map_data_csum = csum_unfold(mpext->csum);
1074 /* Cfr RFC 8684 Section 3.3.0 */
1075 if (unlikely(subflow->map_csum_reqd != csum_reqd))
1076 return MAPPING_INVALID;
1078 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1079 subflow->map_seq, subflow->map_subflow_seq,
1080 subflow->map_data_len, subflow->map_csum_reqd,
1081 subflow->map_data_csum);
1084 /* we revalidate valid mapping on new skb, because we must ensure
1085 * the current skb is completely covered by the available mapping
1087 if (!validate_mapping(ssk, skb)) {
1088 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1089 return MAPPING_INVALID;
1092 skb_ext_del(skb, SKB_EXT_MPTCP);
1095 return validate_data_csum(ssk, skb, csum_reqd);
1098 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1101 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1102 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1105 incr = limit >= skb->len ? skb->len + fin : limit;
1107 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1108 subflow->map_subflow_seq);
1109 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1110 tcp_sk(ssk)->copied_seq += incr;
1111 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1112 sk_eat_skb(ssk, skb);
1113 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1114 subflow->map_valid = 0;
1117 /* sched mptcp worker to remove the subflow if no more data is pending */
1118 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1120 if (likely(ssk->sk_state != TCP_CLOSE))
1123 if (skb_queue_empty(&ssk->sk_receive_queue) &&
1124 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
1125 mptcp_schedule_work((struct sock *)msk);
1128 static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
1130 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1132 if (subflow->mp_join)
1134 else if (READ_ONCE(msk->csum_enabled))
1135 return !subflow->valid_csum_seen;
1137 return !subflow->fully_established;
1140 static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1142 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1143 unsigned long fail_tout;
1145 /* greceful failure can happen only on the MPC subflow */
1146 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1149 /* since the close timeout take precedence on the fail one,
1150 * no need to start the latter when the first is already set
1152 if (sock_flag((struct sock *)msk, SOCK_DEAD))
1155 /* we don't need extreme accuracy here, use a zero fail_tout as special
1156 * value meaning no fail timeout at all;
1158 fail_tout = jiffies + TCP_RTO_MAX;
1161 WRITE_ONCE(subflow->fail_tout, fail_tout);
1164 mptcp_reset_tout_timer(msk, subflow->fail_tout);
1167 static bool subflow_check_data_avail(struct sock *ssk)
1169 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1170 enum mapping_status status;
1171 struct mptcp_sock *msk;
1172 struct sk_buff *skb;
1174 if (!skb_peek(&ssk->sk_receive_queue))
1175 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1176 if (subflow->data_avail)
1179 msk = mptcp_sk(subflow->conn);
1184 status = get_mapping_status(ssk, msk);
1185 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1186 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1187 status == MAPPING_BAD_CSUM))
1190 if (status != MAPPING_OK)
1193 skb = skb_peek(&ssk->sk_receive_queue);
1194 if (WARN_ON_ONCE(!skb))
1197 /* if msk lacks the remote key, this subflow must provide an
1198 * MP_CAPABLE-based mapping
1200 if (unlikely(!READ_ONCE(msk->can_ack))) {
1201 if (!subflow->mpc_map)
1203 WRITE_ONCE(msk->remote_key, subflow->remote_key);
1204 WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1205 WRITE_ONCE(msk->can_ack, true);
1208 old_ack = READ_ONCE(msk->ack_seq);
1209 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1210 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1212 if (unlikely(before64(ack_seq, old_ack))) {
1213 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1217 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1223 subflow_sched_work_if_closed(msk, ssk);
1227 if (!__mptcp_check_fallback(msk)) {
1228 /* RFC 8684 section 3.7. */
1229 if (status == MAPPING_BAD_CSUM &&
1230 (subflow->mp_join || subflow->valid_csum_seen)) {
1231 subflow->send_mp_fail = 1;
1233 if (!READ_ONCE(msk->allow_infinite_fallback)) {
1234 subflow->reset_transient = 0;
1235 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1238 mptcp_subflow_fail(msk, ssk);
1239 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1243 if (!subflow_can_fallback(subflow) && subflow->map_data_len) {
1244 /* fatal protocol error, close the socket.
1245 * subflow_error_report() will introduce the appropriate barriers
1247 subflow->reset_transient = 0;
1248 subflow->reset_reason = MPTCP_RST_EMPTCP;
1251 WRITE_ONCE(ssk->sk_err, EBADMSG);
1252 tcp_set_state(ssk, TCP_CLOSE);
1253 while ((skb = skb_peek(&ssk->sk_receive_queue)))
1254 sk_eat_skb(ssk, skb);
1255 tcp_send_active_reset(ssk, GFP_ATOMIC);
1256 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1260 mptcp_do_fallback(ssk);
1263 skb = skb_peek(&ssk->sk_receive_queue);
1264 subflow->map_valid = 1;
1265 subflow->map_seq = READ_ONCE(msk->ack_seq);
1266 subflow->map_data_len = skb->len;
1267 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1268 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1272 bool mptcp_subflow_data_available(struct sock *sk)
1274 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1276 /* check if current mapping is still valid */
1277 if (subflow->map_valid &&
1278 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1279 subflow->map_valid = 0;
1280 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
1282 pr_debug("Done with mapping: seq=%u data_len=%u",
1283 subflow->map_subflow_seq,
1284 subflow->map_data_len);
1287 return subflow_check_data_avail(sk);
1290 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1293 * In mptcp, rwin is about the mptcp-level connection data.
1295 * Data that is still on the ssk rx queue can thus be ignored,
1296 * as far as mptcp peer is concerned that data is still inflight.
1297 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1299 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1301 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1302 const struct sock *sk = subflow->conn;
1304 *space = __mptcp_space(sk);
1305 *full_space = tcp_full_space(sk);
1308 static void subflow_error_report(struct sock *ssk)
1310 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1312 /* bail early if this is a no-op, so that we avoid introducing a
1313 * problematic lockdep dependency between TCP accept queue lock
1314 * and msk socket spinlock
1319 mptcp_data_lock(sk);
1320 if (!sock_owned_by_user(sk))
1321 __mptcp_error_report(sk);
1323 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
1324 mptcp_data_unlock(sk);
1327 static void subflow_data_ready(struct sock *sk)
1329 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1330 u16 state = 1 << inet_sk_state_load(sk);
1331 struct sock *parent = subflow->conn;
1332 struct mptcp_sock *msk;
1334 msk = mptcp_sk(parent);
1335 if (state & TCPF_LISTEN) {
1336 /* MPJ subflow are removed from accept queue before reaching here,
1337 * avoid stray wakeups
1339 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1342 parent->sk_data_ready(parent);
1346 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1347 !subflow->mp_join && !(state & TCPF_CLOSE));
1349 if (mptcp_subflow_data_available(sk))
1350 mptcp_data_ready(parent, sk);
1351 else if (unlikely(sk->sk_err))
1352 subflow_error_report(sk);
1355 static void subflow_write_space(struct sock *ssk)
1357 struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1359 mptcp_propagate_sndbuf(sk, ssk);
1360 mptcp_write_space(sk);
1363 static const struct inet_connection_sock_af_ops *
1364 subflow_default_af_ops(struct sock *sk)
1366 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1367 if (sk->sk_family == AF_INET6)
1368 return &subflow_v6_specific;
1370 return &subflow_specific;
1373 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1374 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1376 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1377 struct inet_connection_sock *icsk = inet_csk(sk);
1378 const struct inet_connection_sock_af_ops *target;
1380 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1382 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1383 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1385 if (likely(icsk->icsk_af_ops == target))
1388 subflow->icsk_af_ops = icsk->icsk_af_ops;
1389 icsk->icsk_af_ops = target;
1393 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1394 struct sockaddr_storage *addr,
1395 unsigned short family)
1397 memset(addr, 0, sizeof(*addr));
1398 addr->ss_family = family;
1399 if (addr->ss_family == AF_INET) {
1400 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1402 if (info->family == AF_INET)
1403 in_addr->sin_addr = info->addr;
1404 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1405 else if (ipv6_addr_v4mapped(&info->addr6))
1406 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1408 in_addr->sin_port = info->port;
1410 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1411 else if (addr->ss_family == AF_INET6) {
1412 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1414 if (info->family == AF_INET)
1415 ipv6_addr_set_v4mapped(info->addr.s_addr,
1416 &in6_addr->sin6_addr);
1418 in6_addr->sin6_addr = info->addr6;
1419 in6_addr->sin6_port = info->port;
1424 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1425 const struct mptcp_addr_info *remote)
1427 struct mptcp_sock *msk = mptcp_sk(sk);
1428 struct mptcp_subflow_context *subflow;
1429 struct sockaddr_storage addr;
1430 int remote_id = remote->id;
1431 int local_id = loc->id;
1432 int err = -ENOTCONN;
1440 if (!mptcp_is_fully_established(sk))
1443 err = mptcp_subflow_create_socket(sk, loc->family, &sf);
1448 subflow = mptcp_subflow_ctx(ssk);
1450 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1451 } while (!subflow->local_nonce);
1454 subflow_set_local_id(subflow, local_id);
1456 mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id,
1458 subflow->remote_key = msk->remote_key;
1459 subflow->local_key = msk->local_key;
1460 subflow->token = msk->token;
1461 mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1463 addrlen = sizeof(struct sockaddr_in);
1464 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1465 if (addr.ss_family == AF_INET6)
1466 addrlen = sizeof(struct sockaddr_in6);
1468 mptcp_sockopt_sync(msk, ssk);
1470 ssk->sk_bound_dev_if = ifindex;
1471 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1475 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1476 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1477 remote_token, local_id, remote_id);
1478 subflow->remote_token = remote_token;
1479 subflow->remote_id = remote_id;
1480 subflow->request_join = 1;
1481 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1482 mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1485 list_add_tail(&subflow->node, &msk->conn_list);
1486 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1487 if (err && err != -EINPROGRESS)
1490 /* discard the subflow socket */
1491 mptcp_sock_graft(ssk, sk->sk_socket);
1492 iput(SOCK_INODE(sf));
1493 WRITE_ONCE(msk->allow_infinite_fallback, false);
1494 mptcp_stop_tout_timer(sk);
1498 list_del(&subflow->node);
1499 sock_put(mptcp_subflow_tcp_sock(subflow));
1502 subflow->disposable = 1;
1506 /* we account subflows before the creation, and this failures will not
1507 * be caught by sk_state_change()
1509 mptcp_pm_close_subflow(msk);
1513 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1515 #ifdef CONFIG_SOCK_CGROUP_DATA
1516 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1517 *child_skcd = &child->sk_cgrp_data;
1519 /* only the additional subflows created by kworkers have to be modified */
1520 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1521 cgroup_id(sock_cgroup_ptr(child_skcd))) {
1523 struct mem_cgroup *memcg = parent->sk_memcg;
1525 mem_cgroup_sk_free(child);
1526 if (memcg && css_tryget(&memcg->css))
1527 child->sk_memcg = memcg;
1528 #endif /* CONFIG_MEMCG */
1530 cgroup_sk_free(child_skcd);
1531 *child_skcd = *parent_skcd;
1532 cgroup_sk_clone(child_skcd);
1534 #endif /* CONFIG_SOCK_CGROUP_DATA */
1537 static void mptcp_subflow_ops_override(struct sock *ssk)
1539 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1540 if (ssk->sk_prot == &tcpv6_prot)
1541 ssk->sk_prot = &tcpv6_prot_override;
1544 ssk->sk_prot = &tcp_prot_override;
1547 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1549 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1550 if (ssk->sk_prot == &tcpv6_prot_override)
1551 ssk->sk_prot = &tcpv6_prot;
1554 ssk->sk_prot = &tcp_prot;
1557 int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1558 struct socket **new_sock)
1560 struct mptcp_subflow_context *subflow;
1561 struct net *net = sock_net(sk);
1565 /* un-accepted server sockets can reach here - on bad configuration
1566 * bail early to avoid greater trouble later
1568 if (unlikely(!sk->sk_socket))
1571 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
1575 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
1577 /* the newly created socket has to be in the same cgroup as its parent */
1578 mptcp_attach_cgroup(sk, sf->sk);
1580 /* kernel sockets do not by default acquire net ref, but TCP timer
1583 sf->sk->sk_net_refcnt = 1;
1584 get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL);
1585 sock_inuse_add(net, 1);
1586 err = tcp_set_ulp(sf->sk, "mptcp");
1587 release_sock(sf->sk);
1594 /* the newly created socket really belongs to the owning MPTCP master
1595 * socket, even if for additional subflows the allocation is performed
1596 * by a kernel workqueue. Adjust inode references, so that the
1597 * procfs/diag interfaces really show this one belonging to the correct
1600 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1601 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1602 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1604 subflow = mptcp_subflow_ctx(sf->sk);
1605 pr_debug("subflow=%p", subflow);
1610 mptcp_subflow_ops_override(sf->sk);
1615 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1618 struct inet_connection_sock *icsk = inet_csk(sk);
1619 struct mptcp_subflow_context *ctx;
1621 ctx = kzalloc(sizeof(*ctx), priority);
1625 rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1626 INIT_LIST_HEAD(&ctx->node);
1627 INIT_LIST_HEAD(&ctx->delegated_node);
1629 pr_debug("subflow=%p", ctx);
1636 static void __subflow_state_change(struct sock *sk)
1638 struct socket_wq *wq;
1641 wq = rcu_dereference(sk->sk_wq);
1642 if (skwq_has_sleeper(wq))
1643 wake_up_interruptible_all(&wq->wait);
1647 static bool subflow_is_done(const struct sock *sk)
1649 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1652 static void subflow_state_change(struct sock *sk)
1654 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1655 struct sock *parent = subflow->conn;
1656 struct mptcp_sock *msk;
1658 __subflow_state_change(sk);
1660 msk = mptcp_sk(parent);
1661 if (subflow_simultaneous_connect(sk)) {
1662 mptcp_propagate_sndbuf(parent, sk);
1663 mptcp_do_fallback(sk);
1664 mptcp_rcv_space_init(msk, sk);
1666 subflow->conn_finished = 1;
1667 mptcp_set_connected(parent);
1670 /* as recvmsg() does not acquire the subflow socket for ssk selection
1671 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1672 * the data available machinery here.
1674 if (mptcp_subflow_data_available(sk))
1675 mptcp_data_ready(parent, sk);
1676 else if (unlikely(sk->sk_err))
1677 subflow_error_report(sk);
1679 subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1681 /* when the fallback subflow closes the rx side, trigger a 'dummy'
1682 * ingress data fin, so that the msk state will follow along
1684 if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
1685 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
1686 mptcp_schedule_work(parent);
1689 void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1691 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
1692 struct request_sock *req, *head, *tail;
1693 struct mptcp_subflow_context *subflow;
1694 struct sock *sk, *ssk;
1696 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
1697 * Splice the req list, so that accept() can not reach the pending ssk after
1698 * the listener socket is released below.
1700 spin_lock_bh(&queue->rskq_lock);
1701 head = queue->rskq_accept_head;
1702 tail = queue->rskq_accept_tail;
1703 queue->rskq_accept_head = NULL;
1704 queue->rskq_accept_tail = NULL;
1705 spin_unlock_bh(&queue->rskq_lock);
1710 /* can't acquire the msk socket lock under the subflow one,
1711 * or will cause ABBA deadlock
1713 release_sock(listener_ssk);
1715 for (req = head; req; req = req->dl_next) {
1717 if (!sk_is_mptcp(ssk))
1720 subflow = mptcp_subflow_ctx(ssk);
1721 if (!subflow || !subflow->conn)
1727 lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1728 __mptcp_unaccepted_force_close(sk);
1731 /* lockdep will report a false positive ABBA deadlock
1732 * between cancel_work_sync and the listener socket.
1733 * The involved locks belong to different sockets WRT
1734 * the existing AB chain.
1735 * Using a per socket key is problematic as key
1736 * deregistration requires process context and must be
1737 * performed at socket disposal time, in atomic
1739 * Just tell lockdep to consider the listener socket
1742 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1743 mptcp_cancel_work(sk);
1744 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
1749 /* we are still under the listener msk socket lock */
1750 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
1752 /* restore the listener queue, to let the TCP code clean it up */
1753 spin_lock_bh(&queue->rskq_lock);
1754 WARN_ON_ONCE(queue->rskq_accept_head);
1755 queue->rskq_accept_head = head;
1756 queue->rskq_accept_tail = tail;
1757 spin_unlock_bh(&queue->rskq_lock);
1760 static int subflow_ulp_init(struct sock *sk)
1762 struct inet_connection_sock *icsk = inet_csk(sk);
1763 struct mptcp_subflow_context *ctx;
1764 struct tcp_sock *tp = tcp_sk(sk);
1767 /* disallow attaching ULP to a socket unless it has been
1768 * created with sock_create_kern()
1770 if (!sk->sk_kern_sock) {
1775 ctx = subflow_create_ctx(sk, GFP_KERNEL);
1781 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1784 ctx->icsk_af_ops = icsk->icsk_af_ops;
1785 icsk->icsk_af_ops = subflow_default_af_ops(sk);
1786 ctx->tcp_state_change = sk->sk_state_change;
1787 ctx->tcp_error_report = sk->sk_error_report;
1789 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1790 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1792 sk->sk_data_ready = subflow_data_ready;
1793 sk->sk_write_space = subflow_write_space;
1794 sk->sk_state_change = subflow_state_change;
1795 sk->sk_error_report = subflow_error_report;
1800 static void subflow_ulp_release(struct sock *ssk)
1802 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1803 bool release = true;
1811 /* if the msk has been orphaned, keep the ctx
1812 * alive, will be freed by __mptcp_close_ssk(),
1813 * when the subflow is still unaccepted
1815 release = ctx->disposable || list_empty(&ctx->node);
1817 /* inet_child_forget() does not call sk_state_change(),
1818 * explicitly trigger the socket close machinery
1820 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
1821 &mptcp_sk(sk)->flags))
1822 mptcp_schedule_work(sk);
1826 mptcp_subflow_ops_undo_override(ssk);
1828 kfree_rcu(ctx, rcu);
1831 static void subflow_ulp_clone(const struct request_sock *req,
1833 const gfp_t priority)
1835 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1836 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1837 struct mptcp_subflow_context *new_ctx;
1839 if (!tcp_rsk(req)->is_mptcp ||
1840 (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1841 subflow_ulp_fallback(newsk, old_ctx);
1845 new_ctx = subflow_create_ctx(newsk, priority);
1847 subflow_ulp_fallback(newsk, old_ctx);
1851 new_ctx->conn_finished = 1;
1852 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1853 new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1854 new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1855 new_ctx->rel_write_seq = 1;
1856 new_ctx->tcp_sock = newsk;
1858 if (subflow_req->mp_capable) {
1859 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1860 * is fully established only after we receive the remote key
1862 new_ctx->mp_capable = 1;
1863 new_ctx->local_key = subflow_req->local_key;
1864 new_ctx->token = subflow_req->token;
1865 new_ctx->ssn_offset = subflow_req->ssn_offset;
1866 new_ctx->idsn = subflow_req->idsn;
1868 /* this is the first subflow, id is always 0 */
1869 new_ctx->local_id_valid = 1;
1870 } else if (subflow_req->mp_join) {
1871 new_ctx->ssn_offset = subflow_req->ssn_offset;
1872 new_ctx->mp_join = 1;
1873 new_ctx->fully_established = 1;
1874 new_ctx->backup = subflow_req->backup;
1875 new_ctx->remote_id = subflow_req->remote_id;
1876 new_ctx->token = subflow_req->token;
1877 new_ctx->thmac = subflow_req->thmac;
1879 /* the subflow req id is valid, fetched via subflow_check_req()
1880 * and subflow_token_join_request()
1882 subflow_set_local_id(new_ctx, subflow_req->local_id);
1886 static void tcp_release_cb_override(struct sock *ssk)
1888 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1890 if (mptcp_subflow_has_delegated_action(subflow))
1891 mptcp_subflow_process_delegated(ssk);
1893 tcp_release_cb(ssk);
1896 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1898 .owner = THIS_MODULE,
1899 .init = subflow_ulp_init,
1900 .release = subflow_ulp_release,
1901 .clone = subflow_ulp_clone,
1904 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1906 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1908 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1909 subflow_ops->obj_size, 0,
1911 SLAB_TYPESAFE_BY_RCU,
1913 if (!subflow_ops->slab)
1919 void __init mptcp_subflow_init(void)
1921 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
1922 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
1923 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
1925 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
1926 panic("MPTCP: failed to init subflow v4 request sock ops\n");
1928 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1929 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1931 subflow_specific = ipv4_specific;
1932 subflow_specific.conn_request = subflow_v4_conn_request;
1933 subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1934 subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1935 subflow_specific.rebuild_header = subflow_rebuild_header;
1937 tcp_prot_override = tcp_prot;
1938 tcp_prot_override.release_cb = tcp_release_cb_override;
1940 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1941 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock
1942 * structures for v4 and v6 have the same size. It should not changed in
1943 * the future but better to make sure to be warned if it is no longer
1946 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
1948 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
1949 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
1950 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
1952 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
1953 panic("MPTCP: failed to init subflow v6 request sock ops\n");
1955 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1956 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1958 subflow_v6_specific = ipv6_specific;
1959 subflow_v6_specific.conn_request = subflow_v6_conn_request;
1960 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1961 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1962 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
1964 subflow_v6m_specific = subflow_v6_specific;
1965 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1966 subflow_v6m_specific.send_check = ipv4_specific.send_check;
1967 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1968 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1969 subflow_v6m_specific.net_frag_header_len = 0;
1970 subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
1972 tcpv6_prot_override = tcpv6_prot;
1973 tcpv6_prot_override.release_cb = tcp_release_cb_override;
1976 mptcp_diag_subflow_init(&subflow_ulp_ops);
1978 if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1979 panic("MPTCP: failed to register subflows to ULP\n");