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(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         struct csum_pseudo_header header;
 849         u32 offset, seq, delta;
 850         __wsum csum;
 851         int len;
 852
 853         if (!csum_reqd)
 854                 return MAPPING_OK;
 855
 856         /* mapping already validated on previous traversal */
 857         if (subflow->map_csum_len == subflow->map_data_len)
 858                 return MAPPING_OK;
 859
 860         /* traverse the receive queue, ensuring it contains a full
 861          * DSS mapping and accumulating the related csum.
 862          * Preserve the accoumlate csum across multiple calls, to compute
 863          * the csum only once
 864          */
 865         delta = subflow->map_data_len - subflow->map_csum_len;
 866         for (;;) {
 867                 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
 868                 offset = seq - TCP_SKB_CB(skb)->seq;
 869
 870                 /* if the current skb has not been accounted yet, csum its contents
 871                  * up to the amount covered by the current DSS
 872                  */
 873                 if (offset < skb->len) {
 874                         __wsum csum;
 875
 876                         len = min(skb->len - offset, delta);
 877                         csum = skb_checksum(skb, offset, len, 0);
 878                         subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
 879                                                                 subflow->map_csum_len);
 880
 881                         delta -= len;
 882                         subflow->map_csum_len += len;
 883                 }
 884                 if (delta == 0)
 885                         break;
 886
 887                 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
 888                         /* if this subflow is closed, the partial mapping
 889                          * will be never completed; flush the pending skbs, so
 890                          * that subflow_sched_work_if_closed() can kick in
 891                          */
 892                         if (unlikely(ssk->sk_state == TCP_CLOSE))
 893                                 while ((skb = skb_peek(&ssk->sk_receive_queue)))
 894                                         sk_eat_skb(ssk, skb);
 895
 896                         /* not enough data to validate the csum */
 897                         return MAPPING_EMPTY;
 898                 }
 899
 900                 /* the DSS mapping for next skbs will be validated later,
 901                  * when a get_mapping_status call will process such skb
 902                  */
 903                 skb = skb->next;
 904         }
 905
 906         /* note that 'map_data_len' accounts only for the carried data, does
 907          * not include the eventual seq increment due to the data fin,
 908          * while the pseudo header requires the original DSS data len,
 909          * including that
 910          */
 911         header.data_seq = cpu_to_be64(subflow->map_seq);
 912         header.subflow_seq = htonl(subflow->map_subflow_seq);
 913         header.data_len = htons(subflow->map_data_len + subflow->map_data_fin);
 914         header.csum = 0;
 915
 916         csum = csum_partial(&header, sizeof(header), subflow->map_data_csum);
 917         if (unlikely(csum_fold(csum))) {
 918                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
 919                 subflow->send_mp_fail = 1;
 920                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPFAILTX);
 921                 return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
 922         }
 923
 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_check_data_avail(struct sock *ssk)
1106 {
1107         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1108         enum mapping_status status;
1109         struct mptcp_sock *msk;
1110         struct sk_buff *skb;
1111
1112         if (!skb_peek(&ssk->sk_receive_queue))
1113                 WRITE_ONCE(subflow->data_avail, 0);
1114         if (subflow->data_avail)
1115                 return true;
1116
1117         msk = mptcp_sk(subflow->conn);
1118         for (;;) {
1119                 u64 ack_seq;
1120                 u64 old_ack;
1121
1122                 status = get_mapping_status(ssk, msk);
1123                 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1124                 if (unlikely(status == MAPPING_INVALID))
1125                         goto fallback;
1126
1127                 if (unlikely(status == MAPPING_DUMMY))
1128                         goto fallback;
1129
1130                 if (status != MAPPING_OK)
1131                         goto no_data;
1132
1133                 skb = skb_peek(&ssk->sk_receive_queue);
1134                 if (WARN_ON_ONCE(!skb))
1135                         goto no_data;
1136
1137                 /* if msk lacks the remote key, this subflow must provide an
1138                  * MP_CAPABLE-based mapping
1139                  */
1140                 if (unlikely(!READ_ONCE(msk->can_ack))) {
1141                         if (!subflow->mpc_map)
1142                                 goto fallback;
1143                         WRITE_ONCE(msk->remote_key, subflow->remote_key);
1144                         WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1145                         WRITE_ONCE(msk->can_ack, true);
1146                 }
1147
1148                 old_ack = READ_ONCE(msk->ack_seq);
1149                 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1150                 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1151                          ack_seq);
1152                 if (unlikely(before64(ack_seq, old_ack))) {
1153                         mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1154                         continue;
1155                 }
1156
1157                 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1158                 break;
1159         }
1160         return true;
1161
1162 no_data:
1163         subflow_sched_work_if_closed(msk, ssk);
1164         return false;
1165
1166 fallback:
1167         /* RFC 8684 section 3.7. */
1168         if (subflow->send_mp_fail) {
1169                 if (mptcp_has_another_subflow(ssk)) {
1170                         while ((skb = skb_peek(&ssk->sk_receive_queue)))
1171                                 sk_eat_skb(ssk, skb);
1172                 }
1173                 ssk->sk_err = EBADMSG;
1174                 tcp_set_state(ssk, TCP_CLOSE);
1175                 subflow->reset_transient = 0;
1176                 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1177                 tcp_send_active_reset(ssk, GFP_ATOMIC);
1178                 WRITE_ONCE(subflow->data_avail, 0);
1179                 return true;
1180         }
1181
1182         if (subflow->mp_join || subflow->fully_established) {
1183                 /* fatal protocol error, close the socket.
1184                  * subflow_error_report() will introduce the appropriate barriers
1185                  */
1186                 ssk->sk_err = EBADMSG;
1187                 tcp_set_state(ssk, TCP_CLOSE);
1188                 subflow->reset_transient = 0;
1189                 subflow->reset_reason = MPTCP_RST_EMPTCP;
1190                 tcp_send_active_reset(ssk, GFP_ATOMIC);
1191                 WRITE_ONCE(subflow->data_avail, 0);
1192                 return false;
1193         }
1194
1195         __mptcp_do_fallback(msk);
1196         skb = skb_peek(&ssk->sk_receive_queue);
1197         subflow->map_valid = 1;
1198         subflow->map_seq = READ_ONCE(msk->ack_seq);
1199         subflow->map_data_len = skb->len;
1200         subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1201         WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1202         return true;
1203 }
1204
1205 bool mptcp_subflow_data_available(struct sock *sk)
1206 {
1207         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1208
1209         /* check if current mapping is still valid */
1210         if (subflow->map_valid &&
1211             mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1212                 subflow->map_valid = 0;
1213                 WRITE_ONCE(subflow->data_avail, 0);
1214
1215                 pr_debug("Done with mapping: seq=%u data_len=%u",
1216                          subflow->map_subflow_seq,
1217                          subflow->map_data_len);
1218         }
1219
1220         return subflow_check_data_avail(sk);
1221 }
1222
1223 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1224  * not the ssk one.
1225  *
1226  * In mptcp, rwin is about the mptcp-level connection data.
1227  *
1228  * Data that is still on the ssk rx queue can thus be ignored,
1229  * as far as mptcp peer is concerned that data is still inflight.
1230  * DSS ACK is updated when skb is moved to the mptcp rx queue.
1231  */
1232 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1233 {
1234         const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1235         const struct sock *sk = subflow->conn;
1236
1237         *space = __mptcp_space(sk);
1238         *full_space = tcp_full_space(sk);
1239 }
1240
1241 void __mptcp_error_report(struct sock *sk)
1242 {
1243         struct mptcp_subflow_context *subflow;
1244         struct mptcp_sock *msk = mptcp_sk(sk);
1245
1246         mptcp_for_each_subflow(msk, subflow) {
1247                 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1248                 int err = sock_error(ssk);
1249
1250                 if (!err)
1251                         continue;
1252
1253                 /* only propagate errors on fallen-back sockets or
1254                  * on MPC connect
1255                  */
1256                 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1257                         continue;
1258
1259                 inet_sk_state_store(sk, inet_sk_state_load(ssk));
1260                 sk->sk_err = -err;
1261
1262                 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1263                 smp_wmb();
1264                 sk_error_report(sk);
1265                 break;
1266         }
1267 }
1268
1269 static void subflow_error_report(struct sock *ssk)
1270 {
1271         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1272
1273         mptcp_data_lock(sk);
1274         if (!sock_owned_by_user(sk))
1275                 __mptcp_error_report(sk);
1276         else
1277                 set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->flags);
1278         mptcp_data_unlock(sk);
1279 }
1280
1281 static void subflow_data_ready(struct sock *sk)
1282 {
1283         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1284         u16 state = 1 << inet_sk_state_load(sk);
1285         struct sock *parent = subflow->conn;
1286         struct mptcp_sock *msk;
1287
1288         msk = mptcp_sk(parent);
1289         if (state & TCPF_LISTEN) {
1290                 /* MPJ subflow are removed from accept queue before reaching here,
1291                  * avoid stray wakeups
1292                  */
1293                 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1294                         return;
1295
1296                 set_bit(MPTCP_DATA_READY, &msk->flags);
1297                 parent->sk_data_ready(parent);
1298                 return;
1299         }
1300
1301         WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1302                      !subflow->mp_join && !(state & TCPF_CLOSE));
1303
1304         if (mptcp_subflow_data_available(sk))
1305                 mptcp_data_ready(parent, sk);
1306         else if (unlikely(sk->sk_err))
1307                 subflow_error_report(sk);
1308 }
1309
1310 static void subflow_write_space(struct sock *ssk)
1311 {
1312         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1313
1314         mptcp_propagate_sndbuf(sk, ssk);
1315         mptcp_write_space(sk);
1316 }
1317
1318 static struct inet_connection_sock_af_ops *
1319 subflow_default_af_ops(struct sock *sk)
1320 {
1321 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1322         if (sk->sk_family == AF_INET6)
1323                 return &subflow_v6_specific;
1324 #endif
1325         return &subflow_specific;
1326 }
1327
1328 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1329 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1330 {
1331         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1332         struct inet_connection_sock *icsk = inet_csk(sk);
1333         struct inet_connection_sock_af_ops *target;
1334
1335         target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1336
1337         pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1338                  subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1339
1340         if (likely(icsk->icsk_af_ops == target))
1341                 return;
1342
1343         subflow->icsk_af_ops = icsk->icsk_af_ops;
1344         icsk->icsk_af_ops = target;
1345 }
1346 #endif
1347
1348 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1349                          struct sockaddr_storage *addr,
1350                          unsigned short family)
1351 {
1352         memset(addr, 0, sizeof(*addr));
1353         addr->ss_family = family;
1354         if (addr->ss_family == AF_INET) {
1355                 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1356
1357                 if (info->family == AF_INET)
1358                         in_addr->sin_addr = info->addr;
1359 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1360                 else if (ipv6_addr_v4mapped(&info->addr6))
1361                         in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1362 #endif
1363                 in_addr->sin_port = info->port;
1364         }
1365 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1366         else if (addr->ss_family == AF_INET6) {
1367                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1368
1369                 if (info->family == AF_INET)
1370                         ipv6_addr_set_v4mapped(info->addr.s_addr,
1371                                                &in6_addr->sin6_addr);
1372                 else
1373                         in6_addr->sin6_addr = info->addr6;
1374                 in6_addr->sin6_port = info->port;
1375         }
1376 #endif
1377 }
1378
1379 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1380                             const struct mptcp_addr_info *remote)
1381 {
1382         struct mptcp_sock *msk = mptcp_sk(sk);
1383         struct mptcp_subflow_context *subflow;
1384         struct sockaddr_storage addr;
1385         int remote_id = remote->id;
1386         int local_id = loc->id;
1387         struct socket *sf;
1388         struct sock *ssk;
1389         u32 remote_token;
1390         int addrlen;
1391         int ifindex;
1392         u8 flags;
1393         int err;
1394
1395         if (!mptcp_is_fully_established(sk))
1396                 return -ENOTCONN;
1397
1398         err = mptcp_subflow_create_socket(sk, &sf);
1399         if (err)
1400                 return err;
1401
1402         ssk = sf->sk;
1403         subflow = mptcp_subflow_ctx(ssk);
1404         do {
1405                 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1406         } while (!subflow->local_nonce);
1407
1408         if (!local_id) {
1409                 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
1410                 if (err < 0)
1411                         goto failed;
1412
1413                 local_id = err;
1414         }
1415
1416         mptcp_pm_get_flags_and_ifindex_by_id(sock_net(sk), local_id,
1417                                              &flags, &ifindex);
1418         subflow->remote_key = msk->remote_key;
1419         subflow->local_key = msk->local_key;
1420         subflow->token = msk->token;
1421         mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1422
1423         addrlen = sizeof(struct sockaddr_in);
1424 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1425         if (addr.ss_family == AF_INET6)
1426                 addrlen = sizeof(struct sockaddr_in6);
1427 #endif
1428         ssk->sk_bound_dev_if = ifindex;
1429         err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1430         if (err)
1431                 goto failed;
1432
1433         mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1434         pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1435                  remote_token, local_id, remote_id);
1436         subflow->remote_token = remote_token;
1437         subflow->local_id = local_id;
1438         subflow->remote_id = remote_id;
1439         subflow->request_join = 1;
1440         subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1441         mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1442
1443         mptcp_add_pending_subflow(msk, subflow);
1444         mptcp_sockopt_sync(msk, ssk);
1445         err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1446         if (err && err != -EINPROGRESS)
1447                 goto failed_unlink;
1448
1449         /* discard the subflow socket */
1450         mptcp_sock_graft(ssk, sk->sk_socket);
1451         iput(SOCK_INODE(sf));
1452         return err;
1453
1454 failed_unlink:
1455         spin_lock_bh(&msk->join_list_lock);
1456         list_del(&subflow->node);
1457         spin_unlock_bh(&msk->join_list_lock);
1458         sock_put(mptcp_subflow_tcp_sock(subflow));
1459
1460 failed:
1461         subflow->disposable = 1;
1462         sock_release(sf);
1463         return err;
1464 }
1465
1466 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1467 {
1468 #ifdef CONFIG_SOCK_CGROUP_DATA
1469         struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1470                                 *child_skcd = &child->sk_cgrp_data;
1471
1472         /* only the additional subflows created by kworkers have to be modified */
1473         if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1474             cgroup_id(sock_cgroup_ptr(child_skcd))) {
1475 #ifdef CONFIG_MEMCG
1476                 struct mem_cgroup *memcg = parent->sk_memcg;
1477
1478                 mem_cgroup_sk_free(child);
1479                 if (memcg && css_tryget(&memcg->css))
1480                         child->sk_memcg = memcg;
1481 #endif /* CONFIG_MEMCG */
1482
1483                 cgroup_sk_free(child_skcd);
1484                 *child_skcd = *parent_skcd;
1485                 cgroup_sk_clone(child_skcd);
1486         }
1487 #endif /* CONFIG_SOCK_CGROUP_DATA */
1488 }
1489
1490 static void mptcp_subflow_ops_override(struct sock *ssk)
1491 {
1492 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1493         if (ssk->sk_prot == &tcpv6_prot)
1494                 ssk->sk_prot = &tcpv6_prot_override;
1495         else
1496 #endif
1497                 ssk->sk_prot = &tcp_prot_override;
1498 }
1499
1500 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1501 {
1502 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1503         if (ssk->sk_prot == &tcpv6_prot_override)
1504                 ssk->sk_prot = &tcpv6_prot;
1505         else
1506 #endif
1507                 ssk->sk_prot = &tcp_prot;
1508 }
1509 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
1510 {
1511         struct mptcp_subflow_context *subflow;
1512         struct net *net = sock_net(sk);
1513         struct socket *sf;
1514         int err;
1515
1516         /* un-accepted server sockets can reach here - on bad configuration
1517          * bail early to avoid greater trouble later
1518          */
1519         if (unlikely(!sk->sk_socket))
1520                 return -EINVAL;
1521
1522         err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
1523                                &sf);
1524         if (err)
1525                 return err;
1526
1527         lock_sock(sf->sk);
1528
1529         /* the newly created socket has to be in the same cgroup as its parent */
1530         mptcp_attach_cgroup(sk, sf->sk);
1531
1532         /* kernel sockets do not by default acquire net ref, but TCP timer
1533          * needs it.
1534          */
1535         sf->sk->sk_net_refcnt = 1;
1536         get_net(net);
1537 #ifdef CONFIG_PROC_FS
1538         this_cpu_add(*net->core.sock_inuse, 1);
1539 #endif
1540         err = tcp_set_ulp(sf->sk, "mptcp");
1541         release_sock(sf->sk);
1542
1543         if (err) {
1544                 sock_release(sf);
1545                 return err;
1546         }
1547
1548         /* the newly created socket really belongs to the owning MPTCP master
1549          * socket, even if for additional subflows the allocation is performed
1550          * by a kernel workqueue. Adjust inode references, so that the
1551          * procfs/diag interaces really show this one belonging to the correct
1552          * user.
1553          */
1554         SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1555         SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1556         SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1557
1558         subflow = mptcp_subflow_ctx(sf->sk);
1559         pr_debug("subflow=%p", subflow);
1560
1561         *new_sock = sf;
1562         sock_hold(sk);
1563         subflow->conn = sk;
1564         mptcp_subflow_ops_override(sf->sk);
1565
1566         return 0;
1567 }
1568
1569 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1570                                                         gfp_t priority)
1571 {
1572         struct inet_connection_sock *icsk = inet_csk(sk);
1573         struct mptcp_subflow_context *ctx;
1574
1575         ctx = kzalloc(sizeof(*ctx), priority);
1576         if (!ctx)
1577                 return NULL;
1578
1579         rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1580         INIT_LIST_HEAD(&ctx->node);
1581         INIT_LIST_HEAD(&ctx->delegated_node);
1582
1583         pr_debug("subflow=%p", ctx);
1584
1585         ctx->tcp_sock = sk;
1586
1587         return ctx;
1588 }
1589
1590 static void __subflow_state_change(struct sock *sk)
1591 {
1592         struct socket_wq *wq;
1593
1594         rcu_read_lock();
1595         wq = rcu_dereference(sk->sk_wq);
1596         if (skwq_has_sleeper(wq))
1597                 wake_up_interruptible_all(&wq->wait);
1598         rcu_read_unlock();
1599 }
1600
1601 static bool subflow_is_done(const struct sock *sk)
1602 {
1603         return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1604 }
1605
1606 static void subflow_state_change(struct sock *sk)
1607 {
1608         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1609         struct sock *parent = subflow->conn;
1610
1611         __subflow_state_change(sk);
1612
1613         if (subflow_simultaneous_connect(sk)) {
1614                 mptcp_propagate_sndbuf(parent, sk);
1615                 mptcp_do_fallback(sk);
1616                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1617                 pr_fallback(mptcp_sk(parent));
1618                 subflow->conn_finished = 1;
1619                 mptcp_set_connected(parent);
1620         }
1621
1622         /* as recvmsg() does not acquire the subflow socket for ssk selection
1623          * a fin packet carrying a DSS can be unnoticed if we don't trigger
1624          * the data available machinery here.
1625          */
1626         if (mptcp_subflow_data_available(sk))
1627                 mptcp_data_ready(parent, sk);
1628         else if (unlikely(sk->sk_err))
1629                 subflow_error_report(sk);
1630
1631         subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1632
1633         if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1634             !subflow->rx_eof && subflow_is_done(sk)) {
1635                 subflow->rx_eof = 1;
1636                 mptcp_subflow_eof(parent);
1637         }
1638 }
1639
1640 static int subflow_ulp_init(struct sock *sk)
1641 {
1642         struct inet_connection_sock *icsk = inet_csk(sk);
1643         struct mptcp_subflow_context *ctx;
1644         struct tcp_sock *tp = tcp_sk(sk);
1645         int err = 0;
1646
1647         /* disallow attaching ULP to a socket unless it has been
1648          * created with sock_create_kern()
1649          */
1650         if (!sk->sk_kern_sock) {
1651                 err = -EOPNOTSUPP;
1652                 goto out;
1653         }
1654
1655         ctx = subflow_create_ctx(sk, GFP_KERNEL);
1656         if (!ctx) {
1657                 err = -ENOMEM;
1658                 goto out;
1659         }
1660
1661         pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1662
1663         tp->is_mptcp = 1;
1664         ctx->icsk_af_ops = icsk->icsk_af_ops;
1665         icsk->icsk_af_ops = subflow_default_af_ops(sk);
1666         ctx->tcp_data_ready = sk->sk_data_ready;
1667         ctx->tcp_state_change = sk->sk_state_change;
1668         ctx->tcp_write_space = sk->sk_write_space;
1669         ctx->tcp_error_report = sk->sk_error_report;
1670         sk->sk_data_ready = subflow_data_ready;
1671         sk->sk_write_space = subflow_write_space;
1672         sk->sk_state_change = subflow_state_change;
1673         sk->sk_error_report = subflow_error_report;
1674 out:
1675         return err;
1676 }
1677
1678 static void subflow_ulp_release(struct sock *ssk)
1679 {
1680         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1681         bool release = true;
1682         struct sock *sk;
1683
1684         if (!ctx)
1685                 return;
1686
1687         sk = ctx->conn;
1688         if (sk) {
1689                 /* if the msk has been orphaned, keep the ctx
1690                  * alive, will be freed by __mptcp_close_ssk(),
1691                  * when the subflow is still unaccepted
1692                  */
1693                 release = ctx->disposable || list_empty(&ctx->node);
1694                 sock_put(sk);
1695         }
1696
1697         mptcp_subflow_ops_undo_override(ssk);
1698         if (release)
1699                 kfree_rcu(ctx, rcu);
1700 }
1701
1702 static void subflow_ulp_clone(const struct request_sock *req,
1703                               struct sock *newsk,
1704                               const gfp_t priority)
1705 {
1706         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1707         struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1708         struct mptcp_subflow_context *new_ctx;
1709
1710         if (!tcp_rsk(req)->is_mptcp ||
1711             (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1712                 subflow_ulp_fallback(newsk, old_ctx);
1713                 return;
1714         }
1715
1716         new_ctx = subflow_create_ctx(newsk, priority);
1717         if (!new_ctx) {
1718                 subflow_ulp_fallback(newsk, old_ctx);
1719                 return;
1720         }
1721
1722         new_ctx->conn_finished = 1;
1723         new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1724         new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
1725         new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1726         new_ctx->tcp_write_space = old_ctx->tcp_write_space;
1727         new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1728         new_ctx->rel_write_seq = 1;
1729         new_ctx->tcp_sock = newsk;
1730
1731         if (subflow_req->mp_capable) {
1732                 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1733                  * is fully established only after we receive the remote key
1734                  */
1735                 new_ctx->mp_capable = 1;
1736                 new_ctx->local_key = subflow_req->local_key;
1737                 new_ctx->token = subflow_req->token;
1738                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1739                 new_ctx->idsn = subflow_req->idsn;
1740         } else if (subflow_req->mp_join) {
1741                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1742                 new_ctx->mp_join = 1;
1743                 new_ctx->fully_established = 1;
1744                 new_ctx->backup = subflow_req->backup;
1745                 new_ctx->local_id = subflow_req->local_id;
1746                 new_ctx->remote_id = subflow_req->remote_id;
1747                 new_ctx->token = subflow_req->token;
1748                 new_ctx->thmac = subflow_req->thmac;
1749         }
1750 }
1751
1752 static void tcp_release_cb_override(struct sock *ssk)
1753 {
1754         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1755
1756         if (mptcp_subflow_has_delegated_action(subflow))
1757                 mptcp_subflow_process_delegated(ssk);
1758
1759         tcp_release_cb(ssk);
1760 }
1761
1762 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1763         .name           = "mptcp",
1764         .owner          = THIS_MODULE,
1765         .init           = subflow_ulp_init,
1766         .release        = subflow_ulp_release,
1767         .clone          = subflow_ulp_clone,
1768 };
1769
1770 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1771 {
1772         subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1773         subflow_ops->slab_name = "request_sock_subflow";
1774
1775         subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1776                                               subflow_ops->obj_size, 0,
1777                                               SLAB_ACCOUNT |
1778                                               SLAB_TYPESAFE_BY_RCU,
1779                                               NULL);
1780         if (!subflow_ops->slab)
1781                 return -ENOMEM;
1782
1783         subflow_ops->destructor = subflow_req_destructor;
1784
1785         return 0;
1786 }
1787
1788 void __init mptcp_subflow_init(void)
1789 {
1790         mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
1791         if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
1792                 panic("MPTCP: failed to init subflow request sock ops\n");
1793
1794         subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1795         subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1796
1797         subflow_specific = ipv4_specific;
1798         subflow_specific.conn_request = subflow_v4_conn_request;
1799         subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1800         subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1801
1802         tcp_prot_override = tcp_prot;
1803         tcp_prot_override.release_cb = tcp_release_cb_override;
1804
1805 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1806         subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1807         subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1808
1809         subflow_v6_specific = ipv6_specific;
1810         subflow_v6_specific.conn_request = subflow_v6_conn_request;
1811         subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1812         subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1813
1814         subflow_v6m_specific = subflow_v6_specific;
1815         subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1816         subflow_v6m_specific.send_check = ipv4_specific.send_check;
1817         subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1818         subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1819         subflow_v6m_specific.net_frag_header_len = 0;
1820
1821         tcpv6_prot_override = tcpv6_prot;
1822         tcpv6_prot_override.release_cb = tcp_release_cb_override;
1823 #endif
1824
1825         mptcp_diag_subflow_init(&subflow_ulp_ops);
1826
1827         if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1828                 panic("MPTCP: failed to register subflows to ULP\n");
1829 }