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(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(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)->cb_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(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(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(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         u16 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                 subflow->send_mp_fail = 1;
 917                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPFAILTX);
 918                 return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
 919         }
 920
 921         return MAPPING_OK;
 922 }
 923
 924 static enum mapping_status get_mapping_status(struct sock *ssk,
 925                                               struct mptcp_sock *msk)
 926 {
 927         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 928         bool csum_reqd = READ_ONCE(msk->csum_enabled);
 929         struct mptcp_ext *mpext;
 930         struct sk_buff *skb;
 931         u16 data_len;
 932         u64 map_seq;
 933
 934         skb = skb_peek(&ssk->sk_receive_queue);
 935         if (!skb)
 936                 return MAPPING_EMPTY;
 937
 938         if (mptcp_check_fallback(ssk))
 939                 return MAPPING_DUMMY;
 940
 941         mpext = mptcp_get_ext(skb);
 942         if (!mpext || !mpext->use_map) {
 943                 if (!subflow->map_valid && !skb->len) {
 944                         /* the TCP stack deliver 0 len FIN pkt to the receive
 945                          * queue, that is the only 0len pkts ever expected here,
 946                          * and we can admit no mapping only for 0 len pkts
 947                          */
 948                         if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
 949                                 WARN_ONCE(1, "0len seq %d:%d flags %x",
 950                                           TCP_SKB_CB(skb)->seq,
 951                                           TCP_SKB_CB(skb)->end_seq,
 952                                           TCP_SKB_CB(skb)->tcp_flags);
 953                         sk_eat_skb(ssk, skb);
 954                         return MAPPING_EMPTY;
 955                 }
 956
 957                 if (!subflow->map_valid)
 958                         return MAPPING_INVALID;
 959
 960                 goto validate_seq;
 961         }
 962
 963         trace_get_mapping_status(mpext);
 964
 965         data_len = mpext->data_len;
 966         if (data_len == 0) {
 967                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
 968                 return MAPPING_INVALID;
 969         }
 970
 971         if (mpext->data_fin == 1) {
 972                 if (data_len == 1) {
 973                         bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
 974                                                                  mpext->dsn64);
 975                         pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
 976                         if (subflow->map_valid) {
 977                                 /* A DATA_FIN might arrive in a DSS
 978                                  * option before the previous mapping
 979                                  * has been fully consumed. Continue
 980                                  * handling the existing mapping.
 981                                  */
 982                                 skb_ext_del(skb, SKB_EXT_MPTCP);
 983                                 return MAPPING_OK;
 984                         } else {
 985                                 if (updated && schedule_work(&msk->work))
 986                                         sock_hold((struct sock *)msk);
 987
 988                                 return MAPPING_DATA_FIN;
 989                         }
 990                 } else {
 991                         u64 data_fin_seq = mpext->data_seq + data_len - 1;
 992
 993                         /* If mpext->data_seq is a 32-bit value, data_fin_seq
 994                          * must also be limited to 32 bits.
 995                          */
 996                         if (!mpext->dsn64)
 997                                 data_fin_seq &= GENMASK_ULL(31, 0);
 998
 999                         mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1000                         pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
1001                                  data_fin_seq, mpext->dsn64);
1002                 }
1003
1004                 /* Adjust for DATA_FIN using 1 byte of sequence space */
1005                 data_len--;
1006         }
1007
1008         map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1009         WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1010
1011         if (subflow->map_valid) {
1012                 /* Allow replacing only with an identical map */
1013                 if (subflow->map_seq == map_seq &&
1014                     subflow->map_subflow_seq == mpext->subflow_seq &&
1015                     subflow->map_data_len == data_len &&
1016                     subflow->map_csum_reqd == mpext->csum_reqd) {
1017                         skb_ext_del(skb, SKB_EXT_MPTCP);
1018                         goto validate_csum;
1019                 }
1020
1021                 /* If this skb data are fully covered by the current mapping,
1022                  * the new map would need caching, which is not supported
1023                  */
1024                 if (skb_is_fully_mapped(ssk, skb)) {
1025                         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1026                         return MAPPING_INVALID;
1027                 }
1028
1029                 /* will validate the next map after consuming the current one */
1030                 goto validate_csum;
1031         }
1032
1033         subflow->map_seq = map_seq;
1034         subflow->map_subflow_seq = mpext->subflow_seq;
1035         subflow->map_data_len = data_len;
1036         subflow->map_valid = 1;
1037         subflow->map_data_fin = mpext->data_fin;
1038         subflow->mpc_map = mpext->mpc_map;
1039         subflow->map_csum_reqd = mpext->csum_reqd;
1040         subflow->map_csum_len = 0;
1041         subflow->map_data_csum = csum_unfold(mpext->csum);
1042
1043         /* Cfr RFC 8684 Section 3.3.0 */
1044         if (unlikely(subflow->map_csum_reqd != csum_reqd))
1045                 return MAPPING_INVALID;
1046
1047         pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1048                  subflow->map_seq, subflow->map_subflow_seq,
1049                  subflow->map_data_len, subflow->map_csum_reqd,
1050                  subflow->map_data_csum);
1051
1052 validate_seq:
1053         /* we revalidate valid mapping on new skb, because we must ensure
1054          * the current skb is completely covered by the available mapping
1055          */
1056         if (!validate_mapping(ssk, skb)) {
1057                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1058                 return MAPPING_INVALID;
1059         }
1060
1061         skb_ext_del(skb, SKB_EXT_MPTCP);
1062
1063 validate_csum:
1064         return validate_data_csum(ssk, skb, csum_reqd);
1065 }
1066
1067 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1068                                        u64 limit)
1069 {
1070         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1071         bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1072         u32 incr;
1073
1074         incr = limit >= skb->len ? skb->len + fin : limit;
1075
1076         pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1077                  subflow->map_subflow_seq);
1078         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1079         tcp_sk(ssk)->copied_seq += incr;
1080         if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1081                 sk_eat_skb(ssk, skb);
1082         if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1083                 subflow->map_valid = 0;
1084 }
1085
1086 /* sched mptcp worker to remove the subflow if no more data is pending */
1087 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1088 {
1089         struct sock *sk = (struct sock *)msk;
1090
1091         if (likely(ssk->sk_state != TCP_CLOSE))
1092                 return;
1093
1094         if (skb_queue_empty(&ssk->sk_receive_queue) &&
1095             !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
1096                 sock_hold(sk);
1097                 if (!schedule_work(&msk->work))
1098                         sock_put(sk);
1099         }
1100 }
1101
1102 static bool subflow_check_data_avail(struct sock *ssk)
1103 {
1104         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1105         enum mapping_status status;
1106         struct mptcp_sock *msk;
1107         struct sk_buff *skb;
1108
1109         if (!skb_peek(&ssk->sk_receive_queue))
1110                 WRITE_ONCE(subflow->data_avail, 0);
1111         if (subflow->data_avail)
1112                 return true;
1113
1114         msk = mptcp_sk(subflow->conn);
1115         for (;;) {
1116                 u64 ack_seq;
1117                 u64 old_ack;
1118
1119                 status = get_mapping_status(ssk, msk);
1120                 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1121                 if (unlikely(status == MAPPING_INVALID))
1122                         goto fallback;
1123
1124                 if (unlikely(status == MAPPING_DUMMY))
1125                         goto fallback;
1126
1127                 if (status != MAPPING_OK)
1128                         goto no_data;
1129
1130                 skb = skb_peek(&ssk->sk_receive_queue);
1131                 if (WARN_ON_ONCE(!skb))
1132                         goto no_data;
1133
1134                 /* if msk lacks the remote key, this subflow must provide an
1135                  * MP_CAPABLE-based mapping
1136                  */
1137                 if (unlikely(!READ_ONCE(msk->can_ack))) {
1138                         if (!subflow->mpc_map)
1139                                 goto fallback;
1140                         WRITE_ONCE(msk->remote_key, subflow->remote_key);
1141                         WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1142                         WRITE_ONCE(msk->can_ack, true);
1143                 }
1144
1145                 old_ack = READ_ONCE(msk->ack_seq);
1146                 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1147                 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1148                          ack_seq);
1149                 if (unlikely(before64(ack_seq, old_ack))) {
1150                         mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1151                         continue;
1152                 }
1153
1154                 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1155                 break;
1156         }
1157         return true;
1158
1159 no_data:
1160         subflow_sched_work_if_closed(msk, ssk);
1161         return false;
1162
1163 fallback:
1164         /* RFC 8684 section 3.7. */
1165         if (subflow->send_mp_fail) {
1166                 if (mptcp_has_another_subflow(ssk)) {
1167                         while ((skb = skb_peek(&ssk->sk_receive_queue)))
1168                                 sk_eat_skb(ssk, skb);
1169                 }
1170                 ssk->sk_err = EBADMSG;
1171                 tcp_set_state(ssk, TCP_CLOSE);
1172                 subflow->reset_transient = 0;
1173                 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1174                 tcp_send_active_reset(ssk, GFP_ATOMIC);
1175                 WRITE_ONCE(subflow->data_avail, 0);
1176                 return true;
1177         }
1178
1179         if (subflow->mp_join || subflow->fully_established) {
1180                 /* fatal protocol error, close the socket.
1181                  * subflow_error_report() will introduce the appropriate barriers
1182                  */
1183                 ssk->sk_err = EBADMSG;
1184                 tcp_set_state(ssk, TCP_CLOSE);
1185                 subflow->reset_transient = 0;
1186                 subflow->reset_reason = MPTCP_RST_EMPTCP;
1187                 tcp_send_active_reset(ssk, GFP_ATOMIC);
1188                 WRITE_ONCE(subflow->data_avail, 0);
1189                 return false;
1190         }
1191
1192         __mptcp_do_fallback(msk);
1193         skb = skb_peek(&ssk->sk_receive_queue);
1194         subflow->map_valid = 1;
1195         subflow->map_seq = READ_ONCE(msk->ack_seq);
1196         subflow->map_data_len = skb->len;
1197         subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1198         WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1199         return true;
1200 }
1201
1202 bool mptcp_subflow_data_available(struct sock *sk)
1203 {
1204         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1205
1206         /* check if current mapping is still valid */
1207         if (subflow->map_valid &&
1208             mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1209                 subflow->map_valid = 0;
1210                 WRITE_ONCE(subflow->data_avail, 0);
1211
1212                 pr_debug("Done with mapping: seq=%u data_len=%u",
1213                          subflow->map_subflow_seq,
1214                          subflow->map_data_len);
1215         }
1216
1217         return subflow_check_data_avail(sk);
1218 }
1219
1220 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1221  * not the ssk one.
1222  *
1223  * In mptcp, rwin is about the mptcp-level connection data.
1224  *
1225  * Data that is still on the ssk rx queue can thus be ignored,
1226  * as far as mptcp peer is concerned that data is still inflight.
1227  * DSS ACK is updated when skb is moved to the mptcp rx queue.
1228  */
1229 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1230 {
1231         const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1232         const struct sock *sk = subflow->conn;
1233
1234         *space = __mptcp_space(sk);
1235         *full_space = tcp_full_space(sk);
1236 }
1237
1238 void __mptcp_error_report(struct sock *sk)
1239 {
1240         struct mptcp_subflow_context *subflow;
1241         struct mptcp_sock *msk = mptcp_sk(sk);
1242
1243         mptcp_for_each_subflow(msk, subflow) {
1244                 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1245                 int err = sock_error(ssk);
1246
1247                 if (!err)
1248                         continue;
1249
1250                 /* only propagate errors on fallen-back sockets or
1251                  * on MPC connect
1252                  */
1253                 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1254                         continue;
1255
1256                 inet_sk_state_store(sk, inet_sk_state_load(ssk));
1257                 sk->sk_err = -err;
1258
1259                 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1260                 smp_wmb();
1261                 sk_error_report(sk);
1262                 break;
1263         }
1264 }
1265
1266 static void subflow_error_report(struct sock *ssk)
1267 {
1268         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1269
1270         mptcp_data_lock(sk);
1271         if (!sock_owned_by_user(sk))
1272                 __mptcp_error_report(sk);
1273         else
1274                 __set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->cb_flags);
1275         mptcp_data_unlock(sk);
1276 }
1277
1278 static void subflow_data_ready(struct sock *sk)
1279 {
1280         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1281         u16 state = 1 << inet_sk_state_load(sk);
1282         struct sock *parent = subflow->conn;
1283         struct mptcp_sock *msk;
1284
1285         msk = mptcp_sk(parent);
1286         if (state & TCPF_LISTEN) {
1287                 /* MPJ subflow are removed from accept queue before reaching here,
1288                  * avoid stray wakeups
1289                  */
1290                 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1291                         return;
1292
1293                 parent->sk_data_ready(parent);
1294                 return;
1295         }
1296
1297         WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1298                      !subflow->mp_join && !(state & TCPF_CLOSE));
1299
1300         if (mptcp_subflow_data_available(sk))
1301                 mptcp_data_ready(parent, sk);
1302         else if (unlikely(sk->sk_err))
1303                 subflow_error_report(sk);
1304 }
1305
1306 static void subflow_write_space(struct sock *ssk)
1307 {
1308         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1309
1310         mptcp_propagate_sndbuf(sk, ssk);
1311         mptcp_write_space(sk);
1312 }
1313
1314 static struct inet_connection_sock_af_ops *
1315 subflow_default_af_ops(struct sock *sk)
1316 {
1317 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1318         if (sk->sk_family == AF_INET6)
1319                 return &subflow_v6_specific;
1320 #endif
1321         return &subflow_specific;
1322 }
1323
1324 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1325 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1326 {
1327         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1328         struct inet_connection_sock *icsk = inet_csk(sk);
1329         struct inet_connection_sock_af_ops *target;
1330
1331         target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1332
1333         pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1334                  subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1335
1336         if (likely(icsk->icsk_af_ops == target))
1337                 return;
1338
1339         subflow->icsk_af_ops = icsk->icsk_af_ops;
1340         icsk->icsk_af_ops = target;
1341 }
1342 #endif
1343
1344 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1345                          struct sockaddr_storage *addr,
1346                          unsigned short family)
1347 {
1348         memset(addr, 0, sizeof(*addr));
1349         addr->ss_family = family;
1350         if (addr->ss_family == AF_INET) {
1351                 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1352
1353                 if (info->family == AF_INET)
1354                         in_addr->sin_addr = info->addr;
1355 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1356                 else if (ipv6_addr_v4mapped(&info->addr6))
1357                         in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1358 #endif
1359                 in_addr->sin_port = info->port;
1360         }
1361 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1362         else if (addr->ss_family == AF_INET6) {
1363                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1364
1365                 if (info->family == AF_INET)
1366                         ipv6_addr_set_v4mapped(info->addr.s_addr,
1367                                                &in6_addr->sin6_addr);
1368                 else
1369                         in6_addr->sin6_addr = info->addr6;
1370                 in6_addr->sin6_port = info->port;
1371         }
1372 #endif
1373 }
1374
1375 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1376                             const struct mptcp_addr_info *remote)
1377 {
1378         struct mptcp_sock *msk = mptcp_sk(sk);
1379         struct mptcp_subflow_context *subflow;
1380         struct sockaddr_storage addr;
1381         int remote_id = remote->id;
1382         int local_id = loc->id;
1383         struct socket *sf;
1384         struct sock *ssk;
1385         u32 remote_token;
1386         int addrlen;
1387         int ifindex;
1388         u8 flags;
1389         int err;
1390
1391         if (!mptcp_is_fully_established(sk))
1392                 return -ENOTCONN;
1393
1394         err = mptcp_subflow_create_socket(sk, &sf);
1395         if (err)
1396                 return err;
1397
1398         ssk = sf->sk;
1399         subflow = mptcp_subflow_ctx(ssk);
1400         do {
1401                 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1402         } while (!subflow->local_nonce);
1403
1404         if (!local_id) {
1405                 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
1406                 if (err < 0)
1407                         goto failed;
1408
1409                 local_id = err;
1410         }
1411
1412         mptcp_pm_get_flags_and_ifindex_by_id(sock_net(sk), local_id,
1413                                              &flags, &ifindex);
1414         subflow->remote_key = msk->remote_key;
1415         subflow->local_key = msk->local_key;
1416         subflow->token = msk->token;
1417         mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1418
1419         addrlen = sizeof(struct sockaddr_in);
1420 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1421         if (addr.ss_family == AF_INET6)
1422                 addrlen = sizeof(struct sockaddr_in6);
1423 #endif
1424         mptcp_sockopt_sync(msk, ssk);
1425
1426         ssk->sk_bound_dev_if = ifindex;
1427         err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1428         if (err)
1429                 goto failed;
1430
1431         mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1432         pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1433                  remote_token, local_id, remote_id);
1434         subflow->remote_token = remote_token;
1435         subflow->local_id = local_id;
1436         subflow->remote_id = remote_id;
1437         subflow->request_join = 1;
1438         subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1439         mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1440
1441         sock_hold(ssk);
1442         list_add_tail(&subflow->node, &msk->conn_list);
1443         err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1444         if (err && err != -EINPROGRESS)
1445                 goto failed_unlink;
1446
1447         /* discard the subflow socket */
1448         mptcp_sock_graft(ssk, sk->sk_socket);
1449         iput(SOCK_INODE(sf));
1450         return err;
1451
1452 failed_unlink:
1453         list_del(&subflow->node);
1454         sock_put(mptcp_subflow_tcp_sock(subflow));
1455
1456 failed:
1457         subflow->disposable = 1;
1458         sock_release(sf);
1459         return err;
1460 }
1461
1462 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1463 {
1464 #ifdef CONFIG_SOCK_CGROUP_DATA
1465         struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1466                                 *child_skcd = &child->sk_cgrp_data;
1467
1468         /* only the additional subflows created by kworkers have to be modified */
1469         if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1470             cgroup_id(sock_cgroup_ptr(child_skcd))) {
1471 #ifdef CONFIG_MEMCG
1472                 struct mem_cgroup *memcg = parent->sk_memcg;
1473
1474                 mem_cgroup_sk_free(child);
1475                 if (memcg && css_tryget(&memcg->css))
1476                         child->sk_memcg = memcg;
1477 #endif /* CONFIG_MEMCG */
1478
1479                 cgroup_sk_free(child_skcd);
1480                 *child_skcd = *parent_skcd;
1481                 cgroup_sk_clone(child_skcd);
1482         }
1483 #endif /* CONFIG_SOCK_CGROUP_DATA */
1484 }
1485
1486 static void mptcp_subflow_ops_override(struct sock *ssk)
1487 {
1488 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1489         if (ssk->sk_prot == &tcpv6_prot)
1490                 ssk->sk_prot = &tcpv6_prot_override;
1491         else
1492 #endif
1493                 ssk->sk_prot = &tcp_prot_override;
1494 }
1495
1496 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1497 {
1498 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1499         if (ssk->sk_prot == &tcpv6_prot_override)
1500                 ssk->sk_prot = &tcpv6_prot;
1501         else
1502 #endif
1503                 ssk->sk_prot = &tcp_prot;
1504 }
1505 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
1506 {
1507         struct mptcp_subflow_context *subflow;
1508         struct net *net = sock_net(sk);
1509         struct socket *sf;
1510         int err;
1511
1512         /* un-accepted server sockets can reach here - on bad configuration
1513          * bail early to avoid greater trouble later
1514          */
1515         if (unlikely(!sk->sk_socket))
1516                 return -EINVAL;
1517
1518         err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
1519                                &sf);
1520         if (err)
1521                 return err;
1522
1523         lock_sock(sf->sk);
1524
1525         /* the newly created socket has to be in the same cgroup as its parent */
1526         mptcp_attach_cgroup(sk, sf->sk);
1527
1528         /* kernel sockets do not by default acquire net ref, but TCP timer
1529          * needs it.
1530          */
1531         sf->sk->sk_net_refcnt = 1;
1532         get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL);
1533         sock_inuse_add(net, 1);
1534         err = tcp_set_ulp(sf->sk, "mptcp");
1535         release_sock(sf->sk);
1536
1537         if (err) {
1538                 sock_release(sf);
1539                 return err;
1540         }
1541
1542         /* the newly created socket really belongs to the owning MPTCP master
1543          * socket, even if for additional subflows the allocation is performed
1544          * by a kernel workqueue. Adjust inode references, so that the
1545          * procfs/diag interaces really show this one belonging to the correct
1546          * user.
1547          */
1548         SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1549         SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1550         SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1551
1552         subflow = mptcp_subflow_ctx(sf->sk);
1553         pr_debug("subflow=%p", subflow);
1554
1555         *new_sock = sf;
1556         sock_hold(sk);
1557         subflow->conn = sk;
1558         mptcp_subflow_ops_override(sf->sk);
1559
1560         return 0;
1561 }
1562
1563 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1564                                                         gfp_t priority)
1565 {
1566         struct inet_connection_sock *icsk = inet_csk(sk);
1567         struct mptcp_subflow_context *ctx;
1568
1569         ctx = kzalloc(sizeof(*ctx), priority);
1570         if (!ctx)
1571                 return NULL;
1572
1573         rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1574         INIT_LIST_HEAD(&ctx->node);
1575         INIT_LIST_HEAD(&ctx->delegated_node);
1576
1577         pr_debug("subflow=%p", ctx);
1578
1579         ctx->tcp_sock = sk;
1580
1581         return ctx;
1582 }
1583
1584 static void __subflow_state_change(struct sock *sk)
1585 {
1586         struct socket_wq *wq;
1587
1588         rcu_read_lock();
1589         wq = rcu_dereference(sk->sk_wq);
1590         if (skwq_has_sleeper(wq))
1591                 wake_up_interruptible_all(&wq->wait);
1592         rcu_read_unlock();
1593 }
1594
1595 static bool subflow_is_done(const struct sock *sk)
1596 {
1597         return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1598 }
1599
1600 static void subflow_state_change(struct sock *sk)
1601 {
1602         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1603         struct sock *parent = subflow->conn;
1604
1605         __subflow_state_change(sk);
1606
1607         if (subflow_simultaneous_connect(sk)) {
1608                 mptcp_propagate_sndbuf(parent, sk);
1609                 mptcp_do_fallback(sk);
1610                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1611                 pr_fallback(mptcp_sk(parent));
1612                 subflow->conn_finished = 1;
1613                 mptcp_set_connected(parent);
1614         }
1615
1616         /* as recvmsg() does not acquire the subflow socket for ssk selection
1617          * a fin packet carrying a DSS can be unnoticed if we don't trigger
1618          * the data available machinery here.
1619          */
1620         if (mptcp_subflow_data_available(sk))
1621                 mptcp_data_ready(parent, sk);
1622         else if (unlikely(sk->sk_err))
1623                 subflow_error_report(sk);
1624
1625         subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1626
1627         if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1628             !subflow->rx_eof && subflow_is_done(sk)) {
1629                 subflow->rx_eof = 1;
1630                 mptcp_subflow_eof(parent);
1631         }
1632 }
1633
1634 static int subflow_ulp_init(struct sock *sk)
1635 {
1636         struct inet_connection_sock *icsk = inet_csk(sk);
1637         struct mptcp_subflow_context *ctx;
1638         struct tcp_sock *tp = tcp_sk(sk);
1639         int err = 0;
1640
1641         /* disallow attaching ULP to a socket unless it has been
1642          * created with sock_create_kern()
1643          */
1644         if (!sk->sk_kern_sock) {
1645                 err = -EOPNOTSUPP;
1646                 goto out;
1647         }
1648
1649         ctx = subflow_create_ctx(sk, GFP_KERNEL);
1650         if (!ctx) {
1651                 err = -ENOMEM;
1652                 goto out;
1653         }
1654
1655         pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1656
1657         tp->is_mptcp = 1;
1658         ctx->icsk_af_ops = icsk->icsk_af_ops;
1659         icsk->icsk_af_ops = subflow_default_af_ops(sk);
1660         ctx->tcp_data_ready = sk->sk_data_ready;
1661         ctx->tcp_state_change = sk->sk_state_change;
1662         ctx->tcp_write_space = sk->sk_write_space;
1663         ctx->tcp_error_report = sk->sk_error_report;
1664         sk->sk_data_ready = subflow_data_ready;
1665         sk->sk_write_space = subflow_write_space;
1666         sk->sk_state_change = subflow_state_change;
1667         sk->sk_error_report = subflow_error_report;
1668 out:
1669         return err;
1670 }
1671
1672 static void subflow_ulp_release(struct sock *ssk)
1673 {
1674         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1675         bool release = true;
1676         struct sock *sk;
1677
1678         if (!ctx)
1679                 return;
1680
1681         sk = ctx->conn;
1682         if (sk) {
1683                 /* if the msk has been orphaned, keep the ctx
1684                  * alive, will be freed by __mptcp_close_ssk(),
1685                  * when the subflow is still unaccepted
1686                  */
1687                 release = ctx->disposable || list_empty(&ctx->node);
1688                 sock_put(sk);
1689         }
1690
1691         mptcp_subflow_ops_undo_override(ssk);
1692         if (release)
1693                 kfree_rcu(ctx, rcu);
1694 }
1695
1696 static void subflow_ulp_clone(const struct request_sock *req,
1697                               struct sock *newsk,
1698                               const gfp_t priority)
1699 {
1700         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1701         struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1702         struct mptcp_subflow_context *new_ctx;
1703
1704         if (!tcp_rsk(req)->is_mptcp ||
1705             (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1706                 subflow_ulp_fallback(newsk, old_ctx);
1707                 return;
1708         }
1709
1710         new_ctx = subflow_create_ctx(newsk, priority);
1711         if (!new_ctx) {
1712                 subflow_ulp_fallback(newsk, old_ctx);
1713                 return;
1714         }
1715
1716         new_ctx->conn_finished = 1;
1717         new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1718         new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
1719         new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1720         new_ctx->tcp_write_space = old_ctx->tcp_write_space;
1721         new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1722         new_ctx->rel_write_seq = 1;
1723         new_ctx->tcp_sock = newsk;
1724
1725         if (subflow_req->mp_capable) {
1726                 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1727                  * is fully established only after we receive the remote key
1728                  */
1729                 new_ctx->mp_capable = 1;
1730                 new_ctx->local_key = subflow_req->local_key;
1731                 new_ctx->token = subflow_req->token;
1732                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1733                 new_ctx->idsn = subflow_req->idsn;
1734         } else if (subflow_req->mp_join) {
1735                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1736                 new_ctx->mp_join = 1;
1737                 new_ctx->fully_established = 1;
1738                 new_ctx->backup = subflow_req->backup;
1739                 new_ctx->local_id = subflow_req->local_id;
1740                 new_ctx->remote_id = subflow_req->remote_id;
1741                 new_ctx->token = subflow_req->token;
1742                 new_ctx->thmac = subflow_req->thmac;
1743         }
1744 }
1745
1746 static void tcp_release_cb_override(struct sock *ssk)
1747 {
1748         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1749
1750         if (mptcp_subflow_has_delegated_action(subflow))
1751                 mptcp_subflow_process_delegated(ssk);
1752
1753         tcp_release_cb(ssk);
1754 }
1755
1756 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1757         .name           = "mptcp",
1758         .owner          = THIS_MODULE,
1759         .init           = subflow_ulp_init,
1760         .release        = subflow_ulp_release,
1761         .clone          = subflow_ulp_clone,
1762 };
1763
1764 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1765 {
1766         subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1767         subflow_ops->slab_name = "request_sock_subflow";
1768
1769         subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1770                                               subflow_ops->obj_size, 0,
1771                                               SLAB_ACCOUNT |
1772                                               SLAB_TYPESAFE_BY_RCU,
1773                                               NULL);
1774         if (!subflow_ops->slab)
1775                 return -ENOMEM;
1776
1777         subflow_ops->destructor = subflow_req_destructor;
1778
1779         return 0;
1780 }
1781
1782 void __init mptcp_subflow_init(void)
1783 {
1784         mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
1785         if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
1786                 panic("MPTCP: failed to init subflow request sock ops\n");
1787
1788         subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1789         subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1790
1791         subflow_specific = ipv4_specific;
1792         subflow_specific.conn_request = subflow_v4_conn_request;
1793         subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1794         subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1795
1796         tcp_prot_override = tcp_prot;
1797         tcp_prot_override.release_cb = tcp_release_cb_override;
1798
1799 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1800         subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1801         subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1802
1803         subflow_v6_specific = ipv6_specific;
1804         subflow_v6_specific.conn_request = subflow_v6_conn_request;
1805         subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1806         subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1807
1808         subflow_v6m_specific = subflow_v6_specific;
1809         subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1810         subflow_v6m_specific.send_check = ipv4_specific.send_check;
1811         subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1812         subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1813         subflow_v6m_specific.net_frag_header_len = 0;
1814
1815         tcpv6_prot_override = tcpv6_prot;
1816         tcpv6_prot_override.release_cb = tcp_release_cb_override;
1817 #endif
1818
1819         mptcp_diag_subflow_init(&subflow_ulp_ops);
1820
1821         if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1822                 panic("MPTCP: failed to register subflows to ULP\n");
1823 }