net/mptcp/subflow.c

   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
  30 static void mptcp_subflow_ops_undo_override(struct sock *ssk);
  31
  32 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
  33                                   enum linux_mptcp_mib_field field)
  34 {
  35         MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
  36 }
  37
  38 static void subflow_req_destructor(struct request_sock *req)
  39 {
  40         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
  41
  42         pr_debug("subflow_req=%p", subflow_req);
  43
  44         if (subflow_req->msk)
  45                 sock_put((struct sock *)subflow_req->msk);
  46
  47         mptcp_token_destroy_request(req);
  48         tcp_request_sock_ops.destructor(req);
  49 }
  50
  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
  62 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
  63 {
  64         return mptcp_is_fully_established((void *)msk) &&
  65                READ_ONCE(msk->pm.accept_subflow);
  66 }
  67
  68 /* validate received token and create truncated hmac and nonce for SYN-ACK */
  69 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
  70 {
  71         struct mptcp_sock *msk = subflow_req->msk;
  72         u8 hmac[SHA256_DIGEST_SIZE];
  73
  74         get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
  75
  76         subflow_generate_hmac(msk->local_key, msk->remote_key,
  77                               subflow_req->local_nonce,
  78                               subflow_req->remote_nonce, hmac);
  79
  80         subflow_req->thmac = get_unaligned_be64(hmac);
  81 }
  82
  83 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
  84 {
  85         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
  86         struct mptcp_sock *msk;
  87         int local_id;
  88
  89         msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
  90         if (!msk) {
  91                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
  92                 return NULL;
  93         }
  94
  95         local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
  96         if (local_id < 0) {
  97                 sock_put((struct sock *)msk);
  98                 return NULL;
  99         }
 100         subflow_req->local_id = local_id;
 101
 102         return msk;
 103 }
 104
 105 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
 106 {
 107         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 108
 109         subflow_req->mp_capable = 0;
 110         subflow_req->mp_join = 0;
 111         subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
 112         subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
 113         subflow_req->msk = NULL;
 114         mptcp_token_init_request(req);
 115 }
 116
 117 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
 118 {
 119         return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
 120 }
 121
 122 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
 123 {
 124         struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
 125
 126         if (mpext) {
 127                 memset(mpext, 0, sizeof(*mpext));
 128                 mpext->reset_reason = reason;
 129         }
 130 }
 131
 132 /* Init mptcp request socket.
 133  *
 134  * Returns an error code if a JOIN has failed and a TCP reset
 135  * should be sent.
 136  */
 137 static int subflow_check_req(struct request_sock *req,
 138                              const struct sock *sk_listener,
 139                              struct sk_buff *skb)
 140 {
 141         struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 142         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 143         struct mptcp_options_received mp_opt;
 144         bool opt_mp_capable, opt_mp_join;
 145
 146         pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
 147
 148 #ifdef CONFIG_TCP_MD5SIG
 149         /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
 150          * TCP option space.
 151          */
 152         if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
 153                 return -EINVAL;
 154 #endif
 155
 156         mptcp_get_options(sk_listener, skb, &mp_opt);
 157
 158         opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
 159         opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
 160         if (opt_mp_capable) {
 161                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
 162
 163                 if (opt_mp_join)
 164                         return 0;
 165         } else if (opt_mp_join) {
 166                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
 167         }
 168
 169         if (opt_mp_capable && listener->request_mptcp) {
 170                 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
 171
 172                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 173 again:
 174                 do {
 175                         get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
 176                 } while (subflow_req->local_key == 0);
 177
 178                 if (unlikely(req->syncookie)) {
 179                         mptcp_crypto_key_sha(subflow_req->local_key,
 180                                              &subflow_req->token,
 181                                              &subflow_req->idsn);
 182                         if (mptcp_token_exists(subflow_req->token)) {
 183                                 if (retries-- > 0)
 184                                         goto again;
 185                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
 186                         } else {
 187                                 subflow_req->mp_capable = 1;
 188                         }
 189                         return 0;
 190                 }
 191
 192                 err = mptcp_token_new_request(req);
 193                 if (err == 0)
 194                         subflow_req->mp_capable = 1;
 195                 else if (retries-- > 0)
 196                         goto again;
 197                 else
 198                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
 199
 200         } else if (opt_mp_join && listener->request_mptcp) {
 201                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 202                 subflow_req->mp_join = 1;
 203                 subflow_req->backup = mp_opt.backup;
 204                 subflow_req->remote_id = mp_opt.join_id;
 205                 subflow_req->token = mp_opt.token;
 206                 subflow_req->remote_nonce = mp_opt.nonce;
 207                 subflow_req->msk = subflow_token_join_request(req);
 208
 209                 /* Can't fall back to TCP in this case. */
 210                 if (!subflow_req->msk) {
 211                         subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 212                         return -EPERM;
 213                 }
 214
 215                 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
 216                         pr_debug("syn inet_sport=%d %d",
 217                                  ntohs(inet_sk(sk_listener)->inet_sport),
 218                                  ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
 219                         if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
 220                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
 221                                 return -EPERM;
 222                         }
 223                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
 224                 }
 225
 226                 subflow_req_create_thmac(subflow_req);
 227
 228                 if (unlikely(req->syncookie)) {
 229                         if (mptcp_can_accept_new_subflow(subflow_req->msk))
 230                                 subflow_init_req_cookie_join_save(subflow_req, skb);
 231                         else
 232                                 return -EPERM;
 233                 }
 234
 235                 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
 236                          subflow_req->remote_nonce, subflow_req->msk);
 237         }
 238
 239         return 0;
 240 }
 241
 242 int mptcp_subflow_init_cookie_req(struct request_sock *req,
 243                                   const struct sock *sk_listener,
 244                                   struct sk_buff *skb)
 245 {
 246         struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 247         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 248         struct mptcp_options_received mp_opt;
 249         bool opt_mp_capable, opt_mp_join;
 250         int err;
 251
 252         subflow_init_req(req, sk_listener);
 253         mptcp_get_options(sk_listener, skb, &mp_opt);
 254
 255         opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
 256         opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
 257         if (opt_mp_capable && opt_mp_join)
 258                 return -EINVAL;
 259
 260         if (opt_mp_capable && listener->request_mptcp) {
 261                 if (mp_opt.sndr_key == 0)
 262                         return -EINVAL;
 263
 264                 subflow_req->local_key = mp_opt.rcvr_key;
 265                 err = mptcp_token_new_request(req);
 266                 if (err)
 267                         return err;
 268
 269                 subflow_req->mp_capable = 1;
 270                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 271         } else if (opt_mp_join && listener->request_mptcp) {
 272                 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
 273                         return -EINVAL;
 274
 275                 subflow_req->mp_join = 1;
 276                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 277         }
 278
 279         return 0;
 280 }
 281 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
 282
 283 static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
 284                                               struct sk_buff *skb,
 285                                               struct flowi *fl,
 286                                               struct request_sock *req)
 287 {
 288         struct dst_entry *dst;
 289         int err;
 290
 291         tcp_rsk(req)->is_mptcp = 1;
 292         subflow_init_req(req, sk);
 293
 294         dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
 295         if (!dst)
 296                 return NULL;
 297
 298         err = subflow_check_req(req, sk, skb);
 299         if (err == 0)
 300                 return dst;
 301
 302         dst_release(dst);
 303         if (!req->syncookie)
 304                 tcp_request_sock_ops.send_reset(sk, skb);
 305         return NULL;
 306 }
 307
 308 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 309 static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
 310                                               struct sk_buff *skb,
 311                                               struct flowi *fl,
 312                                               struct request_sock *req)
 313 {
 314         struct dst_entry *dst;
 315         int err;
 316
 317         tcp_rsk(req)->is_mptcp = 1;
 318         subflow_init_req(req, sk);
 319
 320         dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
 321         if (!dst)
 322                 return NULL;
 323
 324         err = subflow_check_req(req, sk, skb);
 325         if (err == 0)
 326                 return dst;
 327
 328         dst_release(dst);
 329         if (!req->syncookie)
 330                 tcp6_request_sock_ops.send_reset(sk, skb);
 331         return NULL;
 332 }
 333 #endif
 334
 335 /* validate received truncated hmac and create hmac for third ACK */
 336 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
 337 {
 338         u8 hmac[SHA256_DIGEST_SIZE];
 339         u64 thmac;
 340
 341         subflow_generate_hmac(subflow->remote_key, subflow->local_key,
 342                               subflow->remote_nonce, subflow->local_nonce,
 343                               hmac);
 344
 345         thmac = get_unaligned_be64(hmac);
 346         pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
 347                  subflow, subflow->token,
 348                  (unsigned long long)thmac,
 349                  (unsigned long long)subflow->thmac);
 350
 351         return thmac == subflow->thmac;
 352 }
 353
 354 void mptcp_subflow_reset(struct sock *ssk)
 355 {
 356         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 357         struct sock *sk = subflow->conn;
 358
 359         /* must hold: tcp_done() could drop last reference on parent */
 360         sock_hold(sk);
 361
 362         tcp_set_state(ssk, TCP_CLOSE);
 363         tcp_send_active_reset(ssk, GFP_ATOMIC);
 364         tcp_done(ssk);
 365         if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
 366             schedule_work(&mptcp_sk(sk)->work))
 367                 return; /* worker will put sk for us */
 368
 369         sock_put(sk);
 370 }
 371
 372 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
 373 {
 374         return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
 375 }
 376
 377 void __mptcp_set_connected(struct sock *sk)
 378 {
 379         if (sk->sk_state == TCP_SYN_SENT) {
 380                 inet_sk_state_store(sk, TCP_ESTABLISHED);
 381                 sk->sk_state_change(sk);
 382         }
 383 }
 384
 385 static void mptcp_set_connected(struct sock *sk)
 386 {
 387         mptcp_data_lock(sk);
 388         if (!sock_owned_by_user(sk))
 389                 __mptcp_set_connected(sk);
 390         else
 391                 set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags);
 392         mptcp_data_unlock(sk);
 393 }
 394
 395 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 396 {
 397         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 398         struct mptcp_options_received mp_opt;
 399         struct sock *parent = subflow->conn;
 400
 401         subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 402
 403         /* be sure no special action on any packet other than syn-ack */
 404         if (subflow->conn_finished)
 405                 return;
 406
 407         mptcp_propagate_sndbuf(parent, sk);
 408         subflow->rel_write_seq = 1;
 409         subflow->conn_finished = 1;
 410         subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
 411         pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
 412
 413         mptcp_get_options(sk, skb, &mp_opt);
 414         if (subflow->request_mptcp) {
 415                 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
 416                         MPTCP_INC_STATS(sock_net(sk),
 417                                         MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
 418                         mptcp_do_fallback(sk);
 419                         pr_fallback(mptcp_sk(subflow->conn));
 420                         goto fallback;
 421                 }
 422
 423                 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
 424                         WRITE_ONCE(mptcp_sk(parent)->csum_enabled, true);
 425                 if (mp_opt.deny_join_id0)
 426                         WRITE_ONCE(mptcp_sk(parent)->pm.remote_deny_join_id0, true);
 427                 subflow->mp_capable = 1;
 428                 subflow->can_ack = 1;
 429                 subflow->remote_key = mp_opt.sndr_key;
 430                 pr_debug("subflow=%p, remote_key=%llu", subflow,
 431                          subflow->remote_key);
 432                 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
 433                 mptcp_finish_connect(sk);
 434                 mptcp_set_connected(parent);
 435         } else if (subflow->request_join) {
 436                 u8 hmac[SHA256_DIGEST_SIZE];
 437
 438                 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) {
 439                         subflow->reset_reason = MPTCP_RST_EMPTCP;
 440                         goto do_reset;
 441                 }
 442
 443                 subflow->backup = mp_opt.backup;
 444                 subflow->thmac = mp_opt.thmac;
 445                 subflow->remote_nonce = mp_opt.nonce;
 446                 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
 447                          subflow, subflow->thmac, subflow->remote_nonce,
 448                          subflow->backup);
 449
 450                 if (!subflow_thmac_valid(subflow)) {
 451                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
 452                         subflow->reset_reason = MPTCP_RST_EMPTCP;
 453                         goto do_reset;
 454                 }
 455
 456                 if (!mptcp_finish_join(sk))
 457                         goto do_reset;
 458
 459                 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
 460                                       subflow->local_nonce,
 461                                       subflow->remote_nonce,
 462                                       hmac);
 463                 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
 464
 465                 subflow->mp_join = 1;
 466                 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
 467
 468                 if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
 469                         pr_debug("synack inet_dport=%d %d",
 470                                  ntohs(inet_sk(sk)->inet_dport),
 471                                  ntohs(inet_sk(parent)->inet_dport));
 472                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
 473                 }
 474         } else if (mptcp_check_fallback(sk)) {
 475 fallback:
 476                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
 477                 mptcp_set_connected(parent);
 478         }
 479         return;
 480
 481 do_reset:
 482         subflow->reset_transient = 0;
 483         mptcp_subflow_reset(sk);
 484 }
 485
 486 struct request_sock_ops mptcp_subflow_request_sock_ops;
 487 EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops);
 488 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
 489
 490 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 491 {
 492         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 493
 494         pr_debug("subflow=%p", subflow);
 495
 496         /* Never answer to SYNs sent to broadcast or multicast */
 497         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 498                 goto drop;
 499
 500         return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 501                                 &subflow_request_sock_ipv4_ops,
 502                                 sk, skb);
 503 drop:
 504         tcp_listendrop(sk);
 505         return 0;
 506 }
 507
 508 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 509 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
 510 static struct inet_connection_sock_af_ops subflow_v6_specific;
 511 static struct inet_connection_sock_af_ops subflow_v6m_specific;
 512 static struct proto tcpv6_prot_override;
 513
 514 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 515 {
 516         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 517
 518         pr_debug("subflow=%p", subflow);
 519
 520         if (skb->protocol == htons(ETH_P_IP))
 521                 return subflow_v4_conn_request(sk, skb);
 522
 523         if (!ipv6_unicast_destination(skb))
 524                 goto drop;
 525
 526         if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
 527                 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
 528                 return 0;
 529         }
 530
 531         return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 532                                 &subflow_request_sock_ipv6_ops, sk, skb);
 533
 534 drop:
 535         tcp_listendrop(sk);
 536         return 0; /* don't send reset */
 537 }
 538 #endif
 539
 540 /* validate hmac received in third ACK */
 541 static bool subflow_hmac_valid(const struct request_sock *req,
 542                                const struct mptcp_options_received *mp_opt)
 543 {
 544         const struct mptcp_subflow_request_sock *subflow_req;
 545         u8 hmac[SHA256_DIGEST_SIZE];
 546         struct mptcp_sock *msk;
 547
 548         subflow_req = mptcp_subflow_rsk(req);
 549         msk = subflow_req->msk;
 550         if (!msk)
 551                 return false;
 552
 553         subflow_generate_hmac(msk->remote_key, msk->local_key,
 554                               subflow_req->remote_nonce,
 555                               subflow_req->local_nonce, hmac);
 556
 557         return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
 558 }
 559
 560 static void mptcp_sock_destruct(struct sock *sk)
 561 {
 562         /* if new mptcp socket isn't accepted, it is free'd
 563          * from the tcp listener sockets request queue, linked
 564          * from req->sk.  The tcp socket is released.
 565          * This calls the ULP release function which will
 566          * also remove the mptcp socket, via
 567          * sock_put(ctx->conn).
 568          *
 569          * Problem is that the mptcp socket will be in
 570          * ESTABLISHED state and will not have the SOCK_DEAD flag.
 571          * Both result in warnings from inet_sock_destruct.
 572          */
 573         if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
 574                 sk->sk_state = TCP_CLOSE;
 575                 WARN_ON_ONCE(sk->sk_socket);
 576                 sock_orphan(sk);
 577         }
 578
 579         mptcp_destroy_common(mptcp_sk(sk));
 580         inet_sock_destruct(sk);
 581 }
 582
 583 static void mptcp_force_close(struct sock *sk)
 584 {
 585         /* the msk is not yet exposed to user-space */
 586         inet_sk_state_store(sk, TCP_CLOSE);
 587         sk_common_release(sk);
 588 }
 589
 590 static void subflow_ulp_fallback(struct sock *sk,
 591                                  struct mptcp_subflow_context *old_ctx)
 592 {
 593         struct inet_connection_sock *icsk = inet_csk(sk);
 594
 595         mptcp_subflow_tcp_fallback(sk, old_ctx);
 596         icsk->icsk_ulp_ops = NULL;
 597         rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
 598         tcp_sk(sk)->is_mptcp = 0;
 599
 600         mptcp_subflow_ops_undo_override(sk);
 601 }
 602
 603 static void subflow_drop_ctx(struct sock *ssk)
 604 {
 605         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
 606
 607         if (!ctx)
 608                 return;
 609
 610         subflow_ulp_fallback(ssk, ctx);
 611         if (ctx->conn)
 612                 sock_put(ctx->conn);
 613
 614         kfree_rcu(ctx, rcu);
 615 }
 616
 617 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 618                                      struct mptcp_options_received *mp_opt)
 619 {
 620         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 621
 622         subflow->remote_key = mp_opt->sndr_key;
 623         subflow->fully_established = 1;
 624         subflow->can_ack = 1;
 625         WRITE_ONCE(msk->fully_established, true);
 626 }
 627
 628 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 629                                           struct sk_buff *skb,
 630                                           struct request_sock *req,
 631                                           struct dst_entry *dst,
 632                                           struct request_sock *req_unhash,
 633                                           bool *own_req)
 634 {
 635         struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
 636         struct mptcp_subflow_request_sock *subflow_req;
 637         struct mptcp_options_received mp_opt;
 638         bool fallback, fallback_is_fatal;
 639         struct sock *new_msk = NULL;
 640         struct sock *child;
 641
 642         pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
 643
 644         /* After child creation we must look for MPC even when options
 645          * are not parsed
 646          */
 647         mp_opt.suboptions = 0;
 648
 649         /* hopefully temporary handling for MP_JOIN+syncookie */
 650         subflow_req = mptcp_subflow_rsk(req);
 651         fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
 652         fallback = !tcp_rsk(req)->is_mptcp;
 653         if (fallback)
 654                 goto create_child;
 655
 656         /* if the sk is MP_CAPABLE, we try to fetch the client key */
 657         if (subflow_req->mp_capable) {
 658                 /* we can receive and accept an in-window, out-of-order pkt,
 659                  * which may not carry the MP_CAPABLE opt even on mptcp enabled
 660                  * paths: always try to extract the peer key, and fallback
 661                  * for packets missing it.
 662                  * Even OoO DSS packets coming legitly after dropped or
 663                  * reordered MPC will cause fallback, but we don't have other
 664                  * options.
 665                  */
 666                 mptcp_get_options(sk, skb, &mp_opt);
 667                 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
 668                         fallback = true;
 669                         goto create_child;
 670                 }
 671
 672                 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
 673                 if (!new_msk)
 674                         fallback = true;
 675         } else if (subflow_req->mp_join) {
 676                 mptcp_get_options(sk, skb, &mp_opt);
 677                 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||
 678                     !subflow_hmac_valid(req, &mp_opt) ||
 679                     !mptcp_can_accept_new_subflow(subflow_req->msk)) {
 680                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
 681                         fallback = true;
 682                 }
 683         }
 684
 685 create_child:
 686         child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
 687                                                      req_unhash, own_req);
 688
 689         if (child && *own_req) {
 690                 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
 691
 692                 tcp_rsk(req)->drop_req = false;
 693
 694                 /* we need to fallback on ctx allocation failure and on pre-reqs
 695                  * checking above. In the latter scenario we additionally need
 696                  * to reset the context to non MPTCP status.
 697                  */
 698                 if (!ctx || fallback) {
 699                         if (fallback_is_fatal) {
 700                                 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 701                                 goto dispose_child;
 702                         }
 703
 704                         subflow_drop_ctx(child);
 705                         goto out;
 706                 }
 707
 708                 /* ssk inherits options of listener sk */
 709                 ctx->setsockopt_seq = listener->setsockopt_seq;
 710
 711                 if (ctx->mp_capable) {
 712                         /* this can't race with mptcp_close(), as the msk is
 713                          * not yet exposted to user-space
 714                          */
 715                         inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
 716
 717                         /* record the newly created socket as the first msk
 718                          * subflow, but don't link it yet into conn_list
 719                          */
 720                         WRITE_ONCE(mptcp_sk(new_msk)->first, child);
 721
 722                         /* new mpc subflow takes ownership of the newly
 723                          * created mptcp socket
 724                          */
 725                         new_msk->sk_destruct = mptcp_sock_destruct;
 726                         mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
 727                         mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
 728                         mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
 729                         ctx->conn = new_msk;
 730                         new_msk = NULL;
 731
 732                         /* with OoO packets we can reach here without ingress
 733                          * mpc option
 734                          */
 735                         if (mp_opt.suboptions & OPTIONS_MPTCP_MPC)
 736                                 mptcp_subflow_fully_established(ctx, &mp_opt);
 737                 } else if (ctx->mp_join) {
 738                         struct mptcp_sock *owner;
 739
 740                         owner = subflow_req->msk;
 741                         if (!owner) {
 742                                 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
 743                                 goto dispose_child;
 744                         }
 745
 746                         /* move the msk reference ownership to the subflow */
 747                         subflow_req->msk = NULL;
 748                         ctx->conn = (struct sock *)owner;
 749
 750                         if (subflow_use_different_sport(owner, sk)) {
 751                                 pr_debug("ack inet_sport=%d %d",
 752                                          ntohs(inet_sk(sk)->inet_sport),
 753                                          ntohs(inet_sk((struct sock *)owner)->inet_sport));
 754                                 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
 755                                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
 756                                         goto dispose_child;
 757                                 }
 758                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
 759                         }
 760
 761                         if (!mptcp_finish_join(child))
 762                                 goto dispose_child;
 763
 764                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
 765                         tcp_rsk(req)->drop_req = true;
 766                 }
 767         }
 768
 769 out:
 770         /* dispose of the left over mptcp master, if any */
 771         if (unlikely(new_msk))
 772                 mptcp_force_close(new_msk);
 773
 774         /* check for expected invariant - should never trigger, just help
 775          * catching eariler subtle bugs
 776          */
 777         WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
 778                      (!mptcp_subflow_ctx(child) ||
 779                       !mptcp_subflow_ctx(child)->conn));
 780         return child;
 781
 782 dispose_child:
 783         subflow_drop_ctx(child);
 784         tcp_rsk(req)->drop_req = true;
 785         inet_csk_prepare_for_destroy_sock(child);
 786         tcp_done(child);
 787         req->rsk_ops->send_reset(sk, skb);
 788
 789         /* The last child reference will be released by the caller */
 790         return child;
 791 }
 792
 793 static struct inet_connection_sock_af_ops subflow_specific;
 794 static struct proto tcp_prot_override;
 795
 796 enum mapping_status {
 797         MAPPING_OK,
 798         MAPPING_INVALID,
 799         MAPPING_EMPTY,
 800         MAPPING_DATA_FIN,
 801         MAPPING_DUMMY
 802 };
 803
 804 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
 805 {
 806         pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
 807                  ssn, subflow->map_subflow_seq, subflow->map_data_len);
 808 }
 809
 810 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
 811 {
 812         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 813         unsigned int skb_consumed;
 814
 815         skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
 816         if (WARN_ON_ONCE(skb_consumed >= skb->len))
 817                 return true;
 818
 819         return skb->len - skb_consumed <= subflow->map_data_len -
 820                                           mptcp_subflow_get_map_offset(subflow);
 821 }
 822
 823 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
 824 {
 825         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 826         u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
 827
 828         if (unlikely(before(ssn, subflow->map_subflow_seq))) {
 829                 /* Mapping covers data later in the subflow stream,
 830                  * currently unsupported.
 831                  */
 832                 dbg_bad_map(subflow, ssn);
 833                 return false;
 834         }
 835         if (unlikely(!before(ssn, subflow->map_subflow_seq +
 836                                   subflow->map_data_len))) {
 837                 /* Mapping does covers past subflow data, invalid */
 838                 dbg_bad_map(subflow, ssn);
 839                 return false;
 840         }
 841         return true;
 842 }
 843
 844 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
 845                                               bool csum_reqd)
 846 {
 847         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 848         u32 offset, seq, delta;
 849         __sum16 csum;
 850         int len;
 851
 852         if (!csum_reqd)
 853                 return MAPPING_OK;
 854
 855         /* mapping already validated on previous traversal */
 856         if (subflow->map_csum_len == subflow->map_data_len)
 857                 return MAPPING_OK;
 858
 859         /* traverse the receive queue, ensuring it contains a full
 860          * DSS mapping and accumulating the related csum.
 861          * Preserve the accoumlate csum across multiple calls, to compute
 862          * the csum only once
 863          */
 864         delta = subflow->map_data_len - subflow->map_csum_len;
 865         for (;;) {
 866                 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
 867                 offset = seq - TCP_SKB_CB(skb)->seq;
 868
 869                 /* if the current skb has not been accounted yet, csum its contents
 870                  * up to the amount covered by the current DSS
 871                  */
 872                 if (offset < skb->len) {
 873                         __wsum csum;
 874
 875                         len = min(skb->len - offset, delta);
 876                         csum = skb_checksum(skb, offset, len, 0);
 877                         subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
 878                                                                 subflow->map_csum_len);
 879
 880                         delta -= len;
 881                         subflow->map_csum_len += len;
 882                 }
 883                 if (delta == 0)
 884                         break;
 885
 886                 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
 887                         /* if this subflow is closed, the partial mapping
 888                          * will be never completed; flush the pending skbs, so
 889                          * that subflow_sched_work_if_closed() can kick in
 890                          */
 891                         if (unlikely(ssk->sk_state == TCP_CLOSE))
 892                                 while ((skb = skb_peek(&ssk->sk_receive_queue)))
 893                                         sk_eat_skb(ssk, skb);
 894
 895                         /* not enough data to validate the csum */
 896                         return MAPPING_EMPTY;
 897                 }
 898
 899                 /* the DSS mapping for next skbs will be validated later,
 900                  * when a get_mapping_status call will process such skb
 901                  */
 902                 skb = skb->next;
 903         }
 904
 905         /* note that 'map_data_len' accounts only for the carried data, does
 906          * not include the eventual seq increment due to the data fin,
 907          * while the pseudo header requires the original DSS data len,
 908          * including that
 909          */
 910         csum = __mptcp_make_csum(subflow->map_seq,
 911                                  subflow->map_subflow_seq,
 912                                  subflow->map_data_len + subflow->map_data_fin,
 913                                  subflow->map_data_csum);
 914         if (unlikely(csum)) {
 915                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
 916                 if (subflow->mp_join || subflow->valid_csum_seen) {
 917                         subflow->send_mp_fail = 1;
 918                         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPFAILTX);
 919                 }
 920                 return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
 921         }
 922
 923         subflow->valid_csum_seen = 1;
 924         return MAPPING_OK;
 925 }
 926
 927 static enum mapping_status get_mapping_status(struct sock *ssk,
 928                                               struct mptcp_sock *msk)
 929 {
 930         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 931         bool csum_reqd = READ_ONCE(msk->csum_enabled);
 932         struct mptcp_ext *mpext;
 933         struct sk_buff *skb;
 934         u16 data_len;
 935         u64 map_seq;
 936
 937         skb = skb_peek(&ssk->sk_receive_queue);
 938         if (!skb)
 939                 return MAPPING_EMPTY;
 940
 941         if (mptcp_check_fallback(ssk))
 942                 return MAPPING_DUMMY;
 943
 944         mpext = mptcp_get_ext(skb);
 945         if (!mpext || !mpext->use_map) {
 946                 if (!subflow->map_valid && !skb->len) {
 947                         /* the TCP stack deliver 0 len FIN pkt to the receive
 948                          * queue, that is the only 0len pkts ever expected here,
 949                          * and we can admit no mapping only for 0 len pkts
 950                          */
 951                         if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
 952                                 WARN_ONCE(1, "0len seq %d:%d flags %x",
 953                                           TCP_SKB_CB(skb)->seq,
 954                                           TCP_SKB_CB(skb)->end_seq,
 955                                           TCP_SKB_CB(skb)->tcp_flags);
 956                         sk_eat_skb(ssk, skb);
 957                         return MAPPING_EMPTY;
 958                 }
 959
 960                 if (!subflow->map_valid)
 961                         return MAPPING_INVALID;
 962
 963                 goto validate_seq;
 964         }
 965
 966         trace_get_mapping_status(mpext);
 967
 968         data_len = mpext->data_len;
 969         if (data_len == 0) {
 970                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
 971                 return MAPPING_INVALID;
 972         }
 973
 974         if (mpext->data_fin == 1) {
 975                 if (data_len == 1) {
 976                         bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
 977                                                                  mpext->dsn64);
 978                         pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
 979                         if (subflow->map_valid) {
 980                                 /* A DATA_FIN might arrive in a DSS
 981                                  * option before the previous mapping
 982                                  * has been fully consumed. Continue
 983                                  * handling the existing mapping.
 984                                  */
 985                                 skb_ext_del(skb, SKB_EXT_MPTCP);
 986                                 return MAPPING_OK;
 987                         } else {
 988                                 if (updated && schedule_work(&msk->work))
 989                                         sock_hold((struct sock *)msk);
 990
 991                                 return MAPPING_DATA_FIN;
 992                         }
 993                 } else {
 994                         u64 data_fin_seq = mpext->data_seq + data_len - 1;
 995
 996                         /* If mpext->data_seq is a 32-bit value, data_fin_seq
 997                          * must also be limited to 32 bits.
 998                          */
 999                         if (!mpext->dsn64)
1000                                 data_fin_seq &= GENMASK_ULL(31, 0);
1001
1002                         mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1003                         pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
1004                                  data_fin_seq, mpext->dsn64);
1005                 }
1006
1007                 /* Adjust for DATA_FIN using 1 byte of sequence space */
1008                 data_len--;
1009         }
1010
1011         map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1012         WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1013
1014         if (subflow->map_valid) {
1015                 /* Allow replacing only with an identical map */
1016                 if (subflow->map_seq == map_seq &&
1017                     subflow->map_subflow_seq == mpext->subflow_seq &&
1018                     subflow->map_data_len == data_len &&
1019                     subflow->map_csum_reqd == mpext->csum_reqd) {
1020                         skb_ext_del(skb, SKB_EXT_MPTCP);
1021                         goto validate_csum;
1022                 }
1023
1024                 /* If this skb data are fully covered by the current mapping,
1025                  * the new map would need caching, which is not supported
1026                  */
1027                 if (skb_is_fully_mapped(ssk, skb)) {
1028                         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1029                         return MAPPING_INVALID;
1030                 }
1031
1032                 /* will validate the next map after consuming the current one */
1033                 goto validate_csum;
1034         }
1035
1036         subflow->map_seq = map_seq;
1037         subflow->map_subflow_seq = mpext->subflow_seq;
1038         subflow->map_data_len = data_len;
1039         subflow->map_valid = 1;
1040         subflow->map_data_fin = mpext->data_fin;
1041         subflow->mpc_map = mpext->mpc_map;
1042         subflow->map_csum_reqd = mpext->csum_reqd;
1043         subflow->map_csum_len = 0;
1044         subflow->map_data_csum = csum_unfold(mpext->csum);
1045
1046         /* Cfr RFC 8684 Section 3.3.0 */
1047         if (unlikely(subflow->map_csum_reqd != csum_reqd))
1048                 return MAPPING_INVALID;
1049
1050         pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1051                  subflow->map_seq, subflow->map_subflow_seq,
1052                  subflow->map_data_len, subflow->map_csum_reqd,
1053                  subflow->map_data_csum);
1054
1055 validate_seq:
1056         /* we revalidate valid mapping on new skb, because we must ensure
1057          * the current skb is completely covered by the available mapping
1058          */
1059         if (!validate_mapping(ssk, skb)) {
1060                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1061                 return MAPPING_INVALID;
1062         }
1063
1064         skb_ext_del(skb, SKB_EXT_MPTCP);
1065
1066 validate_csum:
1067         return validate_data_csum(ssk, skb, csum_reqd);
1068 }
1069
1070 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1071                                        u64 limit)
1072 {
1073         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1074         bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1075         u32 incr;
1076
1077         incr = limit >= skb->len ? skb->len + fin : limit;
1078
1079         pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1080                  subflow->map_subflow_seq);
1081         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1082         tcp_sk(ssk)->copied_seq += incr;
1083         if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1084                 sk_eat_skb(ssk, skb);
1085         if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1086                 subflow->map_valid = 0;
1087 }
1088
1089 /* sched mptcp worker to remove the subflow if no more data is pending */
1090 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1091 {
1092         struct sock *sk = (struct sock *)msk;
1093
1094         if (likely(ssk->sk_state != TCP_CLOSE))
1095                 return;
1096
1097         if (skb_queue_empty(&ssk->sk_receive_queue) &&
1098             !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
1099                 sock_hold(sk);
1100                 if (!schedule_work(&msk->work))
1101                         sock_put(sk);
1102         }
1103 }
1104
1105 static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
1106 {
1107         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1108
1109         if (subflow->mp_join)
1110                 return false;
1111         else if (READ_ONCE(msk->csum_enabled))
1112                 return !subflow->valid_csum_seen;
1113         else
1114                 return !subflow->fully_established;
1115 }
1116
1117 static bool subflow_check_data_avail(struct sock *ssk)
1118 {
1119         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1120         enum mapping_status status;
1121         struct mptcp_sock *msk;
1122         struct sk_buff *skb;
1123
1124         if (!skb_peek(&ssk->sk_receive_queue))
1125                 WRITE_ONCE(subflow->data_avail, 0);
1126         if (subflow->data_avail)
1127                 return true;
1128
1129         msk = mptcp_sk(subflow->conn);
1130         for (;;) {
1131                 u64 ack_seq;
1132                 u64 old_ack;
1133
1134                 status = get_mapping_status(ssk, msk);
1135                 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1136                 if (unlikely(status == MAPPING_INVALID))
1137                         goto fallback;
1138
1139                 if (unlikely(status == MAPPING_DUMMY))
1140                         goto fallback;
1141
1142                 if (status != MAPPING_OK)
1143                         goto no_data;
1144
1145                 skb = skb_peek(&ssk->sk_receive_queue);
1146                 if (WARN_ON_ONCE(!skb))
1147                         goto no_data;
1148
1149                 /* if msk lacks the remote key, this subflow must provide an
1150                  * MP_CAPABLE-based mapping
1151                  */
1152                 if (unlikely(!READ_ONCE(msk->can_ack))) {
1153                         if (!subflow->mpc_map)
1154                                 goto fallback;
1155                         WRITE_ONCE(msk->remote_key, subflow->remote_key);
1156                         WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1157                         WRITE_ONCE(msk->can_ack, true);
1158                 }
1159
1160                 old_ack = READ_ONCE(msk->ack_seq);
1161                 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1162                 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1163                          ack_seq);
1164                 if (unlikely(before64(ack_seq, old_ack))) {
1165                         mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1166                         continue;
1167                 }
1168
1169                 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1170                 break;
1171         }
1172         return true;
1173
1174 no_data:
1175         subflow_sched_work_if_closed(msk, ssk);
1176         return false;
1177
1178 fallback:
1179         /* RFC 8684 section 3.7. */
1180         if (subflow->send_mp_fail) {
1181                 if (mptcp_has_another_subflow(ssk)) {
1182                         while ((skb = skb_peek(&ssk->sk_receive_queue)))
1183                                 sk_eat_skb(ssk, skb);
1184                 }
1185                 ssk->sk_err = EBADMSG;
1186                 tcp_set_state(ssk, TCP_CLOSE);
1187                 subflow->reset_transient = 0;
1188                 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1189                 tcp_send_active_reset(ssk, GFP_ATOMIC);
1190                 WRITE_ONCE(subflow->data_avail, 0);
1191                 return true;
1192         }
1193
1194         if (!subflow_can_fallback(subflow)) {
1195                 /* fatal protocol error, close the socket.
1196                  * subflow_error_report() will introduce the appropriate barriers
1197                  */
1198                 ssk->sk_err = EBADMSG;
1199                 tcp_set_state(ssk, TCP_CLOSE);
1200                 subflow->reset_transient = 0;
1201                 subflow->reset_reason = MPTCP_RST_EMPTCP;
1202                 tcp_send_active_reset(ssk, GFP_ATOMIC);
1203                 WRITE_ONCE(subflow->data_avail, 0);
1204                 return false;
1205         }
1206
1207         __mptcp_do_fallback(msk);
1208         skb = skb_peek(&ssk->sk_receive_queue);
1209         subflow->map_valid = 1;
1210         subflow->map_seq = READ_ONCE(msk->ack_seq);
1211         subflow->map_data_len = skb->len;
1212         subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1213         WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1214         return true;
1215 }
1216
1217 bool mptcp_subflow_data_available(struct sock *sk)
1218 {
1219         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1220
1221         /* check if current mapping is still valid */
1222         if (subflow->map_valid &&
1223             mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1224                 subflow->map_valid = 0;
1225                 WRITE_ONCE(subflow->data_avail, 0);
1226
1227                 pr_debug("Done with mapping: seq=%u data_len=%u",
1228                          subflow->map_subflow_seq,
1229                          subflow->map_data_len);
1230         }
1231
1232         return subflow_check_data_avail(sk);
1233 }
1234
1235 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1236  * not the ssk one.
1237  *
1238  * In mptcp, rwin is about the mptcp-level connection data.
1239  *
1240  * Data that is still on the ssk rx queue can thus be ignored,
1241  * as far as mptcp peer is concerned that data is still inflight.
1242  * DSS ACK is updated when skb is moved to the mptcp rx queue.
1243  */
1244 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1245 {
1246         const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1247         const struct sock *sk = subflow->conn;
1248
1249         *space = __mptcp_space(sk);
1250         *full_space = tcp_full_space(sk);
1251 }
1252
1253 void __mptcp_error_report(struct sock *sk)
1254 {
1255         struct mptcp_subflow_context *subflow;
1256         struct mptcp_sock *msk = mptcp_sk(sk);
1257
1258         mptcp_for_each_subflow(msk, subflow) {
1259                 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1260                 int err = sock_error(ssk);
1261
1262                 if (!err)
1263                         continue;
1264
1265                 /* only propagate errors on fallen-back sockets or
1266                  * on MPC connect
1267                  */
1268                 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1269                         continue;
1270
1271                 inet_sk_state_store(sk, inet_sk_state_load(ssk));
1272                 sk->sk_err = -err;
1273
1274                 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1275                 smp_wmb();
1276                 sk_error_report(sk);
1277                 break;
1278         }
1279 }
1280
1281 static void subflow_error_report(struct sock *ssk)
1282 {
1283         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1284
1285         mptcp_data_lock(sk);
1286         if (!sock_owned_by_user(sk))
1287                 __mptcp_error_report(sk);
1288         else
1289                 set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->flags);
1290         mptcp_data_unlock(sk);
1291 }
1292
1293 static void subflow_data_ready(struct sock *sk)
1294 {
1295         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1296         u16 state = 1 << inet_sk_state_load(sk);
1297         struct sock *parent = subflow->conn;
1298         struct mptcp_sock *msk;
1299
1300         msk = mptcp_sk(parent);
1301         if (state & TCPF_LISTEN) {
1302                 /* MPJ subflow are removed from accept queue before reaching here,
1303                  * avoid stray wakeups
1304                  */
1305                 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1306                         return;
1307
1308                 set_bit(MPTCP_DATA_READY, &msk->flags);
1309                 parent->sk_data_ready(parent);
1310                 return;
1311         }
1312
1313         WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1314                      !subflow->mp_join && !(state & TCPF_CLOSE));
1315
1316         if (mptcp_subflow_data_available(sk))
1317                 mptcp_data_ready(parent, sk);
1318         else if (unlikely(sk->sk_err))
1319                 subflow_error_report(sk);
1320 }
1321
1322 static void subflow_write_space(struct sock *ssk)
1323 {
1324         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1325
1326         mptcp_propagate_sndbuf(sk, ssk);
1327         mptcp_write_space(sk);
1328 }
1329
1330 static struct inet_connection_sock_af_ops *
1331 subflow_default_af_ops(struct sock *sk)
1332 {
1333 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1334         if (sk->sk_family == AF_INET6)
1335                 return &subflow_v6_specific;
1336 #endif
1337         return &subflow_specific;
1338 }
1339
1340 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1341 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1342 {
1343         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1344         struct inet_connection_sock *icsk = inet_csk(sk);
1345         struct inet_connection_sock_af_ops *target;
1346
1347         target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1348
1349         pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1350                  subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1351
1352         if (likely(icsk->icsk_af_ops == target))
1353                 return;
1354
1355         subflow->icsk_af_ops = icsk->icsk_af_ops;
1356         icsk->icsk_af_ops = target;
1357 }
1358 #endif
1359
1360 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1361                          struct sockaddr_storage *addr,
1362                          unsigned short family)
1363 {
1364         memset(addr, 0, sizeof(*addr));
1365         addr->ss_family = family;
1366         if (addr->ss_family == AF_INET) {
1367                 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1368
1369                 if (info->family == AF_INET)
1370                         in_addr->sin_addr = info->addr;
1371 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1372                 else if (ipv6_addr_v4mapped(&info->addr6))
1373                         in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1374 #endif
1375                 in_addr->sin_port = info->port;
1376         }
1377 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1378         else if (addr->ss_family == AF_INET6) {
1379                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1380
1381                 if (info->family == AF_INET)
1382                         ipv6_addr_set_v4mapped(info->addr.s_addr,
1383                                                &in6_addr->sin6_addr);
1384                 else
1385                         in6_addr->sin6_addr = info->addr6;
1386                 in6_addr->sin6_port = info->port;
1387         }
1388 #endif
1389 }
1390
1391 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1392                             const struct mptcp_addr_info *remote)
1393 {
1394         struct mptcp_sock *msk = mptcp_sk(sk);
1395         struct mptcp_subflow_context *subflow;
1396         struct sockaddr_storage addr;
1397         int remote_id = remote->id;
1398         int local_id = loc->id;
1399         struct socket *sf;
1400         struct sock *ssk;
1401         u32 remote_token;
1402         int addrlen;
1403         int ifindex;
1404         u8 flags;
1405         int err;
1406
1407         if (!mptcp_is_fully_established(sk))
1408                 return -ENOTCONN;
1409
1410         err = mptcp_subflow_create_socket(sk, &sf);
1411         if (err)
1412                 return err;
1413
1414         ssk = sf->sk;
1415         subflow = mptcp_subflow_ctx(ssk);
1416         do {
1417                 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1418         } while (!subflow->local_nonce);
1419
1420         if (!local_id) {
1421                 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
1422                 if (err < 0)
1423                         goto failed;
1424
1425                 local_id = err;
1426         }
1427
1428         mptcp_pm_get_flags_and_ifindex_by_id(sock_net(sk), local_id,
1429                                              &flags, &ifindex);
1430         subflow->remote_key = msk->remote_key;
1431         subflow->local_key = msk->local_key;
1432         subflow->token = msk->token;
1433         mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1434
1435         addrlen = sizeof(struct sockaddr_in);
1436 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1437         if (addr.ss_family == AF_INET6)
1438                 addrlen = sizeof(struct sockaddr_in6);
1439 #endif
1440         ssk->sk_bound_dev_if = ifindex;
1441         err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1442         if (err)
1443                 goto failed;
1444
1445         mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1446         pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1447                  remote_token, local_id, remote_id);
1448         subflow->remote_token = remote_token;
1449         subflow->local_id = local_id;
1450         subflow->remote_id = remote_id;
1451         subflow->request_join = 1;
1452         subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1453         mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1454
1455         mptcp_add_pending_subflow(msk, subflow);
1456         mptcp_sockopt_sync(msk, ssk);
1457         err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1458         if (err && err != -EINPROGRESS)
1459                 goto failed_unlink;
1460
1461         /* discard the subflow socket */
1462         mptcp_sock_graft(ssk, sk->sk_socket);
1463         iput(SOCK_INODE(sf));
1464         return err;
1465
1466 failed_unlink:
1467         spin_lock_bh(&msk->join_list_lock);
1468         list_del(&subflow->node);
1469         spin_unlock_bh(&msk->join_list_lock);
1470         sock_put(mptcp_subflow_tcp_sock(subflow));
1471
1472 failed:
1473         subflow->disposable = 1;
1474         sock_release(sf);
1475         return err;
1476 }
1477
1478 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1479 {
1480 #ifdef CONFIG_SOCK_CGROUP_DATA
1481         struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1482                                 *child_skcd = &child->sk_cgrp_data;
1483
1484         /* only the additional subflows created by kworkers have to be modified */
1485         if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1486             cgroup_id(sock_cgroup_ptr(child_skcd))) {
1487 #ifdef CONFIG_MEMCG
1488                 struct mem_cgroup *memcg = parent->sk_memcg;
1489
1490                 mem_cgroup_sk_free(child);
1491                 if (memcg && css_tryget(&memcg->css))
1492                         child->sk_memcg = memcg;
1493 #endif /* CONFIG_MEMCG */
1494
1495                 cgroup_sk_free(child_skcd);
1496                 *child_skcd = *parent_skcd;
1497                 cgroup_sk_clone(child_skcd);
1498         }
1499 #endif /* CONFIG_SOCK_CGROUP_DATA */
1500 }
1501
1502 static void mptcp_subflow_ops_override(struct sock *ssk)
1503 {
1504 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1505         if (ssk->sk_prot == &tcpv6_prot)
1506                 ssk->sk_prot = &tcpv6_prot_override;
1507         else
1508 #endif
1509                 ssk->sk_prot = &tcp_prot_override;
1510 }
1511
1512 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1513 {
1514 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1515         if (ssk->sk_prot == &tcpv6_prot_override)
1516                 ssk->sk_prot = &tcpv6_prot;
1517         else
1518 #endif
1519                 ssk->sk_prot = &tcp_prot;
1520 }
1521 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
1522 {
1523         struct mptcp_subflow_context *subflow;
1524         struct net *net = sock_net(sk);
1525         struct socket *sf;
1526         int err;
1527
1528         /* un-accepted server sockets can reach here - on bad configuration
1529          * bail early to avoid greater trouble later
1530          */
1531         if (unlikely(!sk->sk_socket))
1532                 return -EINVAL;
1533
1534         err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
1535                                &sf);
1536         if (err)
1537                 return err;
1538
1539         lock_sock(sf->sk);
1540
1541         /* the newly created socket has to be in the same cgroup as its parent */
1542         mptcp_attach_cgroup(sk, sf->sk);
1543
1544         /* kernel sockets do not by default acquire net ref, but TCP timer
1545          * needs it.
1546          */
1547         sf->sk->sk_net_refcnt = 1;
1548         get_net(net);
1549 #ifdef CONFIG_PROC_FS
1550         this_cpu_add(*net->core.sock_inuse, 1);
1551 #endif
1552         err = tcp_set_ulp(sf->sk, "mptcp");
1553         release_sock(sf->sk);
1554
1555         if (err) {
1556                 sock_release(sf);
1557                 return err;
1558         }
1559
1560         /* the newly created socket really belongs to the owning MPTCP master
1561          * socket, even if for additional subflows the allocation is performed
1562          * by a kernel workqueue. Adjust inode references, so that the
1563          * procfs/diag interaces really show this one belonging to the correct
1564          * user.
1565          */
1566         SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1567         SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1568         SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1569
1570         subflow = mptcp_subflow_ctx(sf->sk);
1571         pr_debug("subflow=%p", subflow);
1572
1573         *new_sock = sf;
1574         sock_hold(sk);
1575         subflow->conn = sk;
1576         mptcp_subflow_ops_override(sf->sk);
1577
1578         return 0;
1579 }
1580
1581 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1582                                                         gfp_t priority)
1583 {
1584         struct inet_connection_sock *icsk = inet_csk(sk);
1585         struct mptcp_subflow_context *ctx;
1586
1587         ctx = kzalloc(sizeof(*ctx), priority);
1588         if (!ctx)
1589                 return NULL;
1590
1591         rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1592         INIT_LIST_HEAD(&ctx->node);
1593         INIT_LIST_HEAD(&ctx->delegated_node);
1594
1595         pr_debug("subflow=%p", ctx);
1596
1597         ctx->tcp_sock = sk;
1598
1599         return ctx;
1600 }
1601
1602 static void __subflow_state_change(struct sock *sk)
1603 {
1604         struct socket_wq *wq;
1605
1606         rcu_read_lock();
1607         wq = rcu_dereference(sk->sk_wq);
1608         if (skwq_has_sleeper(wq))
1609                 wake_up_interruptible_all(&wq->wait);
1610         rcu_read_unlock();
1611 }
1612
1613 static bool subflow_is_done(const struct sock *sk)
1614 {
1615         return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1616 }
1617
1618 static void subflow_state_change(struct sock *sk)
1619 {
1620         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1621         struct sock *parent = subflow->conn;
1622
1623         __subflow_state_change(sk);
1624
1625         if (subflow_simultaneous_connect(sk)) {
1626                 mptcp_propagate_sndbuf(parent, sk);
1627                 mptcp_do_fallback(sk);
1628                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1629                 pr_fallback(mptcp_sk(parent));
1630                 subflow->conn_finished = 1;
1631                 mptcp_set_connected(parent);
1632         }
1633
1634         /* as recvmsg() does not acquire the subflow socket for ssk selection
1635          * a fin packet carrying a DSS can be unnoticed if we don't trigger
1636          * the data available machinery here.
1637          */
1638         if (mptcp_subflow_data_available(sk))
1639                 mptcp_data_ready(parent, sk);
1640         else if (unlikely(sk->sk_err))
1641                 subflow_error_report(sk);
1642
1643         subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1644
1645         if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1646             !subflow->rx_eof && subflow_is_done(sk)) {
1647                 subflow->rx_eof = 1;
1648                 mptcp_subflow_eof(parent);
1649         }
1650 }
1651
1652 static int subflow_ulp_init(struct sock *sk)
1653 {
1654         struct inet_connection_sock *icsk = inet_csk(sk);
1655         struct mptcp_subflow_context *ctx;
1656         struct tcp_sock *tp = tcp_sk(sk);
1657         int err = 0;
1658
1659         /* disallow attaching ULP to a socket unless it has been
1660          * created with sock_create_kern()
1661          */
1662         if (!sk->sk_kern_sock) {
1663                 err = -EOPNOTSUPP;
1664                 goto out;
1665         }
1666
1667         ctx = subflow_create_ctx(sk, GFP_KERNEL);
1668         if (!ctx) {
1669                 err = -ENOMEM;
1670                 goto out;
1671         }
1672
1673         pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1674
1675         tp->is_mptcp = 1;
1676         ctx->icsk_af_ops = icsk->icsk_af_ops;
1677         icsk->icsk_af_ops = subflow_default_af_ops(sk);
1678         ctx->tcp_data_ready = sk->sk_data_ready;
1679         ctx->tcp_state_change = sk->sk_state_change;
1680         ctx->tcp_write_space = sk->sk_write_space;
1681         ctx->tcp_error_report = sk->sk_error_report;
1682         sk->sk_data_ready = subflow_data_ready;
1683         sk->sk_write_space = subflow_write_space;
1684         sk->sk_state_change = subflow_state_change;
1685         sk->sk_error_report = subflow_error_report;
1686 out:
1687         return err;
1688 }
1689
1690 static void subflow_ulp_release(struct sock *ssk)
1691 {
1692         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1693         bool release = true;
1694         struct sock *sk;
1695
1696         if (!ctx)
1697                 return;
1698
1699         sk = ctx->conn;
1700         if (sk) {
1701                 /* if the msk has been orphaned, keep the ctx
1702                  * alive, will be freed by __mptcp_close_ssk(),
1703                  * when the subflow is still unaccepted
1704                  */
1705                 release = ctx->disposable || list_empty(&ctx->node);
1706                 sock_put(sk);
1707         }
1708
1709         mptcp_subflow_ops_undo_override(ssk);
1710         if (release)
1711                 kfree_rcu(ctx, rcu);
1712 }
1713
1714 static void subflow_ulp_clone(const struct request_sock *req,
1715                               struct sock *newsk,
1716                               const gfp_t priority)
1717 {
1718         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1719         struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1720         struct mptcp_subflow_context *new_ctx;
1721
1722         if (!tcp_rsk(req)->is_mptcp ||
1723             (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1724                 subflow_ulp_fallback(newsk, old_ctx);
1725                 return;
1726         }
1727
1728         new_ctx = subflow_create_ctx(newsk, priority);
1729         if (!new_ctx) {
1730                 subflow_ulp_fallback(newsk, old_ctx);
1731                 return;
1732         }
1733
1734         new_ctx->conn_finished = 1;
1735         new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1736         new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
1737         new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1738         new_ctx->tcp_write_space = old_ctx->tcp_write_space;
1739         new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1740         new_ctx->rel_write_seq = 1;
1741         new_ctx->tcp_sock = newsk;
1742
1743         if (subflow_req->mp_capable) {
1744                 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1745                  * is fully established only after we receive the remote key
1746                  */
1747                 new_ctx->mp_capable = 1;
1748                 new_ctx->local_key = subflow_req->local_key;
1749                 new_ctx->token = subflow_req->token;
1750                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1751                 new_ctx->idsn = subflow_req->idsn;
1752         } else if (subflow_req->mp_join) {
1753                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1754                 new_ctx->mp_join = 1;
1755                 new_ctx->fully_established = 1;
1756                 new_ctx->backup = subflow_req->backup;
1757                 new_ctx->local_id = subflow_req->local_id;
1758                 new_ctx->remote_id = subflow_req->remote_id;
1759                 new_ctx->token = subflow_req->token;
1760                 new_ctx->thmac = subflow_req->thmac;
1761         }
1762 }
1763
1764 static void tcp_release_cb_override(struct sock *ssk)
1765 {
1766         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1767
1768         if (mptcp_subflow_has_delegated_action(subflow))
1769                 mptcp_subflow_process_delegated(ssk);
1770
1771         tcp_release_cb(ssk);
1772 }
1773
1774 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1775         .name           = "mptcp",
1776         .owner          = THIS_MODULE,
1777         .init           = subflow_ulp_init,
1778         .release        = subflow_ulp_release,
1779         .clone          = subflow_ulp_clone,
1780 };
1781
1782 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1783 {
1784         subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1785         subflow_ops->slab_name = "request_sock_subflow";
1786
1787         subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1788                                               subflow_ops->obj_size, 0,
1789                                               SLAB_ACCOUNT |
1790                                               SLAB_TYPESAFE_BY_RCU,
1791                                               NULL);
1792         if (!subflow_ops->slab)
1793                 return -ENOMEM;
1794
1795         subflow_ops->destructor = subflow_req_destructor;
1796
1797         return 0;
1798 }
1799
1800 void __init mptcp_subflow_init(void)
1801 {
1802         mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
1803         if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
1804                 panic("MPTCP: failed to init subflow request sock ops\n");
1805
1806         subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1807         subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1808
1809         subflow_specific = ipv4_specific;
1810         subflow_specific.conn_request = subflow_v4_conn_request;
1811         subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1812         subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1813
1814         tcp_prot_override = tcp_prot;
1815         tcp_prot_override.release_cb = tcp_release_cb_override;
1816
1817 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1818         subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1819         subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1820
1821         subflow_v6_specific = ipv6_specific;
1822         subflow_v6_specific.conn_request = subflow_v6_conn_request;
1823         subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1824         subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1825
1826         subflow_v6m_specific = subflow_v6_specific;
1827         subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1828         subflow_v6m_specific.send_check = ipv4_specific.send_check;
1829         subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1830         subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1831         subflow_v6m_specific.net_frag_header_len = 0;
1832
1833         tcpv6_prot_override = tcpv6_prot;
1834         tcpv6_prot_override.release_cb = tcp_release_cb_override;
1835 #endif
1836
1837         mptcp_diag_subflow_init(&subflow_ulp_ops);
1838
1839         if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1840                 panic("MPTCP: failed to register subflows to ULP\n");
1841 }