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
 145         pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
 146
 147 #ifdef CONFIG_TCP_MD5SIG
 148         /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
 149          * TCP option space.
 150          */
 151         if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
 152                 return -EINVAL;
 153 #endif
 154
 155         mptcp_get_options(sk_listener, skb, &mp_opt);
 156
 157         if (mp_opt.mp_capable) {
 158                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
 159
 160                 if (mp_opt.mp_join)
 161                         return 0;
 162         } else if (mp_opt.mp_join) {
 163                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
 164         }
 165
 166         if (mp_opt.mp_capable && listener->request_mptcp) {
 167                 int err, retries = MPTCP_TOKEN_MAX_RETRIES;
 168
 169                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 170 again:
 171                 do {
 172                         get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
 173                 } while (subflow_req->local_key == 0);
 174
 175                 if (unlikely(req->syncookie)) {
 176                         mptcp_crypto_key_sha(subflow_req->local_key,
 177                                              &subflow_req->token,
 178                                              &subflow_req->idsn);
 179                         if (mptcp_token_exists(subflow_req->token)) {
 180                                 if (retries-- > 0)
 181                                         goto again;
 182                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
 183                         } else {
 184                                 subflow_req->mp_capable = 1;
 185                         }
 186                         return 0;
 187                 }
 188
 189                 err = mptcp_token_new_request(req);
 190                 if (err == 0)
 191                         subflow_req->mp_capable = 1;
 192                 else if (retries-- > 0)
 193                         goto again;
 194                 else
 195                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
 196
 197         } else if (mp_opt.mp_join && listener->request_mptcp) {
 198                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 199                 subflow_req->mp_join = 1;
 200                 subflow_req->backup = mp_opt.backup;
 201                 subflow_req->remote_id = mp_opt.join_id;
 202                 subflow_req->token = mp_opt.token;
 203                 subflow_req->remote_nonce = mp_opt.nonce;
 204                 subflow_req->msk = subflow_token_join_request(req);
 205
 206                 /* Can't fall back to TCP in this case. */
 207                 if (!subflow_req->msk) {
 208                         subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 209                         return -EPERM;
 210                 }
 211
 212                 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
 213                         pr_debug("syn inet_sport=%d %d",
 214                                  ntohs(inet_sk(sk_listener)->inet_sport),
 215                                  ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
 216                         if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
 217                                 sock_put((struct sock *)subflow_req->msk);
 218                                 mptcp_token_destroy_request(req);
 219                                 tcp_request_sock_ops.destructor(req);
 220                                 subflow_req->msk = NULL;
 221                                 subflow_req->mp_join = 0;
 222                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
 223                                 return -EPERM;
 224                         }
 225                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
 226                 }
 227
 228                 subflow_req_create_thmac(subflow_req);
 229
 230                 if (unlikely(req->syncookie)) {
 231                         if (mptcp_can_accept_new_subflow(subflow_req->msk))
 232                                 subflow_init_req_cookie_join_save(subflow_req, skb);
 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         int err;
 250
 251         subflow_init_req(req, sk_listener);
 252         mptcp_get_options(sk_listener, skb, &mp_opt);
 253
 254         if (mp_opt.mp_capable && mp_opt.mp_join)
 255                 return -EINVAL;
 256
 257         if (mp_opt.mp_capable && listener->request_mptcp) {
 258                 if (mp_opt.sndr_key == 0)
 259                         return -EINVAL;
 260
 261                 subflow_req->local_key = mp_opt.rcvr_key;
 262                 err = mptcp_token_new_request(req);
 263                 if (err)
 264                         return err;
 265
 266                 subflow_req->mp_capable = 1;
 267                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 268         } else if (mp_opt.mp_join && listener->request_mptcp) {
 269                 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
 270                         return -EINVAL;
 271
 272                 if (mptcp_can_accept_new_subflow(subflow_req->msk))
 273                         subflow_req->mp_join = 1;
 274
 275                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 276         }
 277
 278         return 0;
 279 }
 280 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
 281
 282 static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
 283                                               struct sk_buff *skb,
 284                                               struct flowi *fl,
 285                                               struct request_sock *req)
 286 {
 287         struct dst_entry *dst;
 288         int err;
 289
 290         tcp_rsk(req)->is_mptcp = 1;
 291         subflow_init_req(req, sk);
 292
 293         dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
 294         if (!dst)
 295                 return NULL;
 296
 297         err = subflow_check_req(req, sk, skb);
 298         if (err == 0)
 299                 return dst;
 300
 301         dst_release(dst);
 302         if (!req->syncookie)
 303                 tcp_request_sock_ops.send_reset(sk, skb);
 304         return NULL;
 305 }
 306
 307 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 308 static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
 309                                               struct sk_buff *skb,
 310                                               struct flowi *fl,
 311                                               struct request_sock *req)
 312 {
 313         struct dst_entry *dst;
 314         int err;
 315
 316         tcp_rsk(req)->is_mptcp = 1;
 317         subflow_init_req(req, sk);
 318
 319         dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
 320         if (!dst)
 321                 return NULL;
 322
 323         err = subflow_check_req(req, sk, skb);
 324         if (err == 0)
 325                 return dst;
 326
 327         dst_release(dst);
 328         if (!req->syncookie)
 329                 tcp6_request_sock_ops.send_reset(sk, skb);
 330         return NULL;
 331 }
 332 #endif
 333
 334 /* validate received truncated hmac and create hmac for third ACK */
 335 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
 336 {
 337         u8 hmac[SHA256_DIGEST_SIZE];
 338         u64 thmac;
 339
 340         subflow_generate_hmac(subflow->remote_key, subflow->local_key,
 341                               subflow->remote_nonce, subflow->local_nonce,
 342                               hmac);
 343
 344         thmac = get_unaligned_be64(hmac);
 345         pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
 346                  subflow, subflow->token,
 347                  (unsigned long long)thmac,
 348                  (unsigned long long)subflow->thmac);
 349
 350         return thmac == subflow->thmac;
 351 }
 352
 353 void mptcp_subflow_reset(struct sock *ssk)
 354 {
 355         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 356         struct sock *sk = subflow->conn;
 357
 358         /* must hold: tcp_done() could drop last reference on parent */
 359         sock_hold(sk);
 360
 361         tcp_set_state(ssk, TCP_CLOSE);
 362         tcp_send_active_reset(ssk, GFP_ATOMIC);
 363         tcp_done(ssk);
 364         if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
 365             schedule_work(&mptcp_sk(sk)->work))
 366                 return; /* worker will put sk for us */
 367
 368         sock_put(sk);
 369 }
 370
 371 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
 372 {
 373         return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
 374 }
 375
 376 void __mptcp_set_connected(struct sock *sk)
 377 {
 378         if (sk->sk_state == TCP_SYN_SENT) {
 379                 inet_sk_state_store(sk, TCP_ESTABLISHED);
 380                 sk->sk_state_change(sk);
 381         }
 382 }
 383
 384 static void mptcp_set_connected(struct sock *sk)
 385 {
 386         mptcp_data_lock(sk);
 387         if (!sock_owned_by_user(sk))
 388                 __mptcp_set_connected(sk);
 389         else
 390                 set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags);
 391         mptcp_data_unlock(sk);
 392 }
 393
 394 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 395 {
 396         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 397         struct mptcp_options_received mp_opt;
 398         struct sock *parent = subflow->conn;
 399
 400         subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 401
 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.mp_capable) {
 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.csum_reqd)
 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.mp_join) {
 439                         subflow->reset_reason = MPTCP_RST_EMPTCP;
 440                         goto do_reset;
 441                 }
 442
 443                 subflow->thmac = mp_opt.thmac;
 444                 subflow->remote_nonce = mp_opt.nonce;
 445                 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
 446                          subflow->thmac, subflow->remote_nonce);
 447
 448                 if (!subflow_thmac_valid(subflow)) {
 449                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
 450                         subflow->reset_reason = MPTCP_RST_EMPTCP;
 451                         goto do_reset;
 452                 }
 453
 454                 if (!mptcp_finish_join(sk))
 455                         goto do_reset;
 456
 457                 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
 458                                       subflow->local_nonce,
 459                                       subflow->remote_nonce,
 460                                       hmac);
 461                 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
 462
 463                 subflow->mp_join = 1;
 464                 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
 465
 466                 if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
 467                         pr_debug("synack inet_dport=%d %d",
 468                                  ntohs(inet_sk(sk)->inet_dport),
 469                                  ntohs(inet_sk(parent)->inet_dport));
 470                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
 471                 }
 472         } else if (mptcp_check_fallback(sk)) {
 473 fallback:
 474                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
 475                 mptcp_set_connected(parent);
 476         }
 477         return;
 478
 479 do_reset:
 480         subflow->reset_transient = 0;
 481         mptcp_subflow_reset(sk);
 482 }
 483
 484 struct request_sock_ops mptcp_subflow_request_sock_ops;
 485 EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops);
 486 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
 487
 488 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 489 {
 490         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 491
 492         pr_debug("subflow=%p", subflow);
 493
 494         /* Never answer to SYNs sent to broadcast or multicast */
 495         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 496                 goto drop;
 497
 498         return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 499                                 &subflow_request_sock_ipv4_ops,
 500                                 sk, skb);
 501 drop:
 502         tcp_listendrop(sk);
 503         return 0;
 504 }
 505
 506 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 507 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
 508 static struct inet_connection_sock_af_ops subflow_v6_specific;
 509 static struct inet_connection_sock_af_ops subflow_v6m_specific;
 510 static struct proto tcpv6_prot_override;
 511
 512 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 513 {
 514         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 515
 516         pr_debug("subflow=%p", subflow);
 517
 518         if (skb->protocol == htons(ETH_P_IP))
 519                 return subflow_v4_conn_request(sk, skb);
 520
 521         if (!ipv6_unicast_destination(skb))
 522                 goto drop;
 523
 524         if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
 525                 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
 526                 return 0;
 527         }
 528
 529         return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 530                                 &subflow_request_sock_ipv6_ops, sk, skb);
 531
 532 drop:
 533         tcp_listendrop(sk);
 534         return 0; /* don't send reset */
 535 }
 536 #endif
 537
 538 /* validate hmac received in third ACK */
 539 static bool subflow_hmac_valid(const struct request_sock *req,
 540                                const struct mptcp_options_received *mp_opt)
 541 {
 542         const struct mptcp_subflow_request_sock *subflow_req;
 543         u8 hmac[SHA256_DIGEST_SIZE];
 544         struct mptcp_sock *msk;
 545
 546         subflow_req = mptcp_subflow_rsk(req);
 547         msk = subflow_req->msk;
 548         if (!msk)
 549                 return false;
 550
 551         subflow_generate_hmac(msk->remote_key, msk->local_key,
 552                               subflow_req->remote_nonce,
 553                               subflow_req->local_nonce, hmac);
 554
 555         return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
 556 }
 557
 558 static void mptcp_sock_destruct(struct sock *sk)
 559 {
 560         /* if new mptcp socket isn't accepted, it is free'd
 561          * from the tcp listener sockets request queue, linked
 562          * from req->sk.  The tcp socket is released.
 563          * This calls the ULP release function which will
 564          * also remove the mptcp socket, via
 565          * sock_put(ctx->conn).
 566          *
 567          * Problem is that the mptcp socket will be in
 568          * ESTABLISHED state and will not have the SOCK_DEAD flag.
 569          * Both result in warnings from inet_sock_destruct.
 570          */
 571         if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
 572                 sk->sk_state = TCP_CLOSE;
 573                 WARN_ON_ONCE(sk->sk_socket);
 574                 sock_orphan(sk);
 575         }
 576
 577         mptcp_destroy_common(mptcp_sk(sk));
 578         inet_sock_destruct(sk);
 579 }
 580
 581 static void mptcp_force_close(struct sock *sk)
 582 {
 583         /* the msk is not yet exposed to user-space */
 584         inet_sk_state_store(sk, TCP_CLOSE);
 585         sk_common_release(sk);
 586 }
 587
 588 static void subflow_ulp_fallback(struct sock *sk,
 589                                  struct mptcp_subflow_context *old_ctx)
 590 {
 591         struct inet_connection_sock *icsk = inet_csk(sk);
 592
 593         mptcp_subflow_tcp_fallback(sk, old_ctx);
 594         icsk->icsk_ulp_ops = NULL;
 595         rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
 596         tcp_sk(sk)->is_mptcp = 0;
 597
 598         mptcp_subflow_ops_undo_override(sk);
 599 }
 600
 601 static void subflow_drop_ctx(struct sock *ssk)
 602 {
 603         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
 604
 605         if (!ctx)
 606                 return;
 607
 608         subflow_ulp_fallback(ssk, ctx);
 609         if (ctx->conn)
 610                 sock_put(ctx->conn);
 611
 612         kfree_rcu(ctx, rcu);
 613 }
 614
 615 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 616                                      struct mptcp_options_received *mp_opt)
 617 {
 618         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 619
 620         subflow->remote_key = mp_opt->sndr_key;
 621         subflow->fully_established = 1;
 622         subflow->can_ack = 1;
 623         WRITE_ONCE(msk->fully_established, true);
 624 }
 625
 626 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 627                                           struct sk_buff *skb,
 628                                           struct request_sock *req,
 629                                           struct dst_entry *dst,
 630                                           struct request_sock *req_unhash,
 631                                           bool *own_req)
 632 {
 633         struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
 634         struct mptcp_subflow_request_sock *subflow_req;
 635         struct mptcp_options_received mp_opt;
 636         bool fallback, fallback_is_fatal;
 637         struct sock *new_msk = NULL;
 638         struct sock *child;
 639
 640         pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
 641
 642         /* After child creation we must look for 'mp_capable' even when options
 643          * are not parsed
 644          */
 645         mp_opt.mp_capable = 0;
 646
 647         /* hopefully temporary handling for MP_JOIN+syncookie */
 648         subflow_req = mptcp_subflow_rsk(req);
 649         fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
 650         fallback = !tcp_rsk(req)->is_mptcp;
 651         if (fallback)
 652                 goto create_child;
 653
 654         /* if the sk is MP_CAPABLE, we try to fetch the client key */
 655         if (subflow_req->mp_capable) {
 656                 /* we can receive and accept an in-window, out-of-order pkt,
 657                  * which may not carry the MP_CAPABLE opt even on mptcp enabled
 658                  * paths: always try to extract the peer key, and fallback
 659                  * for packets missing it.
 660                  * Even OoO DSS packets coming legitly after dropped or
 661                  * reordered MPC will cause fallback, but we don't have other
 662                  * options.
 663                  */
 664                 mptcp_get_options(sk, skb, &mp_opt);
 665                 if (!mp_opt.mp_capable) {
 666                         fallback = true;
 667                         goto create_child;
 668                 }
 669
 670                 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
 671                 if (!new_msk)
 672                         fallback = true;
 673         } else if (subflow_req->mp_join) {
 674                 mptcp_get_options(sk, skb, &mp_opt);
 675                 if (!mp_opt.mp_join || !subflow_hmac_valid(req, &mp_opt) ||
 676                     !mptcp_can_accept_new_subflow(subflow_req->msk)) {
 677                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
 678                         fallback = true;
 679                 }
 680         }
 681
 682 create_child:
 683         child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
 684                                                      req_unhash, own_req);
 685
 686         if (child && *own_req) {
 687                 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
 688
 689                 tcp_rsk(req)->drop_req = false;
 690
 691                 /* we need to fallback on ctx allocation failure and on pre-reqs
 692                  * checking above. In the latter scenario we additionally need
 693                  * to reset the context to non MPTCP status.
 694                  */
 695                 if (!ctx || fallback) {
 696                         if (fallback_is_fatal) {
 697                                 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 698                                 goto dispose_child;
 699                         }
 700
 701                         subflow_drop_ctx(child);
 702                         goto out;
 703                 }
 704
 705                 /* ssk inherits options of listener sk */
 706                 ctx->setsockopt_seq = listener->setsockopt_seq;
 707
 708                 if (ctx->mp_capable) {
 709                         /* this can't race with mptcp_close(), as the msk is
 710                          * not yet exposted to user-space
 711                          */
 712                         inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
 713
 714                         /* record the newly created socket as the first msk
 715                          * subflow, but don't link it yet into conn_list
 716                          */
 717                         WRITE_ONCE(mptcp_sk(new_msk)->first, child);
 718
 719                         /* new mpc subflow takes ownership of the newly
 720                          * created mptcp socket
 721                          */
 722                         new_msk->sk_destruct = mptcp_sock_destruct;
 723                         mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
 724                         mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
 725                         mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
 726                         ctx->conn = new_msk;
 727                         new_msk = NULL;
 728
 729                         /* with OoO packets we can reach here without ingress
 730                          * mpc option
 731                          */
 732                         if (mp_opt.mp_capable)
 733                                 mptcp_subflow_fully_established(ctx, &mp_opt);
 734                 } else if (ctx->mp_join) {
 735                         struct mptcp_sock *owner;
 736
 737                         owner = subflow_req->msk;
 738                         if (!owner) {
 739                                 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
 740                                 goto dispose_child;
 741                         }
 742
 743                         /* move the msk reference ownership to the subflow */
 744                         subflow_req->msk = NULL;
 745                         ctx->conn = (struct sock *)owner;
 746
 747                         if (subflow_use_different_sport(owner, sk)) {
 748                                 pr_debug("ack inet_sport=%d %d",
 749                                          ntohs(inet_sk(sk)->inet_sport),
 750                                          ntohs(inet_sk((struct sock *)owner)->inet_sport));
 751                                 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
 752                                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
 753                                         goto dispose_child;
 754                                 }
 755                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
 756                         }
 757
 758                         if (!mptcp_finish_join(child))
 759                                 goto dispose_child;
 760
 761                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
 762                         tcp_rsk(req)->drop_req = true;
 763                 }
 764         }
 765
 766 out:
 767         /* dispose of the left over mptcp master, if any */
 768         if (unlikely(new_msk))
 769                 mptcp_force_close(new_msk);
 770
 771         /* check for expected invariant - should never trigger, just help
 772          * catching eariler subtle bugs
 773          */
 774         WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
 775                      (!mptcp_subflow_ctx(child) ||
 776                       !mptcp_subflow_ctx(child)->conn));
 777         return child;
 778
 779 dispose_child:
 780         subflow_drop_ctx(child);
 781         tcp_rsk(req)->drop_req = true;
 782         inet_csk_prepare_for_destroy_sock(child);
 783         tcp_done(child);
 784         req->rsk_ops->send_reset(sk, skb);
 785
 786         /* The last child reference will be released by the caller */
 787         return child;
 788 }
 789
 790 static struct inet_connection_sock_af_ops subflow_specific;
 791 static struct proto tcp_prot_override;
 792
 793 enum mapping_status {
 794         MAPPING_OK,
 795         MAPPING_INVALID,
 796         MAPPING_EMPTY,
 797         MAPPING_DATA_FIN,
 798         MAPPING_DUMMY
 799 };
 800
 801 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
 802 {
 803         pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
 804                  ssn, subflow->map_subflow_seq, subflow->map_data_len);
 805 }
 806
 807 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
 808 {
 809         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 810         unsigned int skb_consumed;
 811
 812         skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
 813         if (WARN_ON_ONCE(skb_consumed >= skb->len))
 814                 return true;
 815
 816         return skb->len - skb_consumed <= subflow->map_data_len -
 817                                           mptcp_subflow_get_map_offset(subflow);
 818 }
 819
 820 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
 821 {
 822         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 823         u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
 824
 825         if (unlikely(before(ssn, subflow->map_subflow_seq))) {
 826                 /* Mapping covers data later in the subflow stream,
 827                  * currently unsupported.
 828                  */
 829                 dbg_bad_map(subflow, ssn);
 830                 return false;
 831         }
 832         if (unlikely(!before(ssn, subflow->map_subflow_seq +
 833                                   subflow->map_data_len))) {
 834                 /* Mapping does covers past subflow data, invalid */
 835                 dbg_bad_map(subflow, ssn);
 836                 return false;
 837         }
 838         return true;
 839 }
 840
 841 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
 842                                               bool csum_reqd)
 843 {
 844         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 845         struct csum_pseudo_header header;
 846         u32 offset, seq, delta;
 847         __wsum csum;
 848         int len;
 849
 850         if (!csum_reqd)
 851                 return MAPPING_OK;
 852
 853         /* mapping already validated on previous traversal */
 854         if (subflow->map_csum_len == subflow->map_data_len)
 855                 return MAPPING_OK;
 856
 857         /* traverse the receive queue, ensuring it contains a full
 858          * DSS mapping and accumulating the related csum.
 859          * Preserve the accoumlate csum across multiple calls, to compute
 860          * the csum only once
 861          */
 862         delta = subflow->map_data_len - subflow->map_csum_len;
 863         for (;;) {
 864                 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
 865                 offset = seq - TCP_SKB_CB(skb)->seq;
 866
 867                 /* if the current skb has not been accounted yet, csum its contents
 868                  * up to the amount covered by the current DSS
 869                  */
 870                 if (offset < skb->len) {
 871                         __wsum csum;
 872
 873                         len = min(skb->len - offset, delta);
 874                         csum = skb_checksum(skb, offset, len, 0);
 875                         subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
 876                                                                 subflow->map_csum_len);
 877
 878                         delta -= len;
 879                         subflow->map_csum_len += len;
 880                 }
 881                 if (delta == 0)
 882                         break;
 883
 884                 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
 885                         /* if this subflow is closed, the partial mapping
 886                          * will be never completed; flush the pending skbs, so
 887                          * that subflow_sched_work_if_closed() can kick in
 888                          */
 889                         if (unlikely(ssk->sk_state == TCP_CLOSE))
 890                                 while ((skb = skb_peek(&ssk->sk_receive_queue)))
 891                                         sk_eat_skb(ssk, skb);
 892
 893                         /* not enough data to validate the csum */
 894                         return MAPPING_EMPTY;
 895                 }
 896
 897                 /* the DSS mapping for next skbs will be validated later,
 898                  * when a get_mapping_status call will process such skb
 899                  */
 900                 skb = skb->next;
 901         }
 902
 903         /* note that 'map_data_len' accounts only for the carried data, does
 904          * not include the eventual seq increment due to the data fin,
 905          * while the pseudo header requires the original DSS data len,
 906          * including that
 907          */
 908         header.data_seq = cpu_to_be64(subflow->map_seq);
 909         header.subflow_seq = htonl(subflow->map_subflow_seq);
 910         header.data_len = htons(subflow->map_data_len + subflow->map_data_fin);
 911         header.csum = 0;
 912
 913         csum = csum_partial(&header, sizeof(header), subflow->map_data_csum);
 914         if (unlikely(csum_fold(csum))) {
 915                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
 916                 return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
 917         }
 918
 919         return MAPPING_OK;
 920 }
 921
 922 static enum mapping_status get_mapping_status(struct sock *ssk,
 923                                               struct mptcp_sock *msk)
 924 {
 925         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 926         bool csum_reqd = READ_ONCE(msk->csum_enabled);
 927         struct mptcp_ext *mpext;
 928         struct sk_buff *skb;
 929         u16 data_len;
 930         u64 map_seq;
 931
 932         skb = skb_peek(&ssk->sk_receive_queue);
 933         if (!skb)
 934                 return MAPPING_EMPTY;
 935
 936         if (mptcp_check_fallback(ssk))
 937                 return MAPPING_DUMMY;
 938
 939         mpext = mptcp_get_ext(skb);
 940         if (!mpext || !mpext->use_map) {
 941                 if (!subflow->map_valid && !skb->len) {
 942                         /* the TCP stack deliver 0 len FIN pkt to the receive
 943                          * queue, that is the only 0len pkts ever expected here,
 944                          * and we can admit no mapping only for 0 len pkts
 945                          */
 946                         if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
 947                                 WARN_ONCE(1, "0len seq %d:%d flags %x",
 948                                           TCP_SKB_CB(skb)->seq,
 949                                           TCP_SKB_CB(skb)->end_seq,
 950                                           TCP_SKB_CB(skb)->tcp_flags);
 951                         sk_eat_skb(ssk, skb);
 952                         return MAPPING_EMPTY;
 953                 }
 954
 955                 if (!subflow->map_valid)
 956                         return MAPPING_INVALID;
 957
 958                 goto validate_seq;
 959         }
 960
 961         trace_get_mapping_status(mpext);
 962
 963         data_len = mpext->data_len;
 964         if (data_len == 0) {
 965                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
 966                 return MAPPING_INVALID;
 967         }
 968
 969         if (mpext->data_fin == 1) {
 970                 if (data_len == 1) {
 971                         bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
 972                                                                  mpext->dsn64);
 973                         pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
 974                         if (subflow->map_valid) {
 975                                 /* A DATA_FIN might arrive in a DSS
 976                                  * option before the previous mapping
 977                                  * has been fully consumed. Continue
 978                                  * handling the existing mapping.
 979                                  */
 980                                 skb_ext_del(skb, SKB_EXT_MPTCP);
 981                                 return MAPPING_OK;
 982                         } else {
 983                                 if (updated && schedule_work(&msk->work))
 984                                         sock_hold((struct sock *)msk);
 985
 986                                 return MAPPING_DATA_FIN;
 987                         }
 988                 } else {
 989                         u64 data_fin_seq = mpext->data_seq + data_len - 1;
 990
 991                         /* If mpext->data_seq is a 32-bit value, data_fin_seq
 992                          * must also be limited to 32 bits.
 993                          */
 994                         if (!mpext->dsn64)
 995                                 data_fin_seq &= GENMASK_ULL(31, 0);
 996
 997                         mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
 998                         pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
 999                                  data_fin_seq, mpext->dsn64);
1000                 }
1001
1002                 /* Adjust for DATA_FIN using 1 byte of sequence space */
1003                 data_len--;
1004         }
1005
1006         map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1007         WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1008
1009         if (subflow->map_valid) {
1010                 /* Allow replacing only with an identical map */
1011                 if (subflow->map_seq == map_seq &&
1012                     subflow->map_subflow_seq == mpext->subflow_seq &&
1013                     subflow->map_data_len == data_len &&
1014                     subflow->map_csum_reqd == mpext->csum_reqd) {
1015                         skb_ext_del(skb, SKB_EXT_MPTCP);
1016                         goto validate_csum;
1017                 }
1018
1019                 /* If this skb data are fully covered by the current mapping,
1020                  * the new map would need caching, which is not supported
1021                  */
1022                 if (skb_is_fully_mapped(ssk, skb)) {
1023                         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1024                         return MAPPING_INVALID;
1025                 }
1026
1027                 /* will validate the next map after consuming the current one */
1028                 goto validate_csum;
1029         }
1030
1031         subflow->map_seq = map_seq;
1032         subflow->map_subflow_seq = mpext->subflow_seq;
1033         subflow->map_data_len = data_len;
1034         subflow->map_valid = 1;
1035         subflow->map_data_fin = mpext->data_fin;
1036         subflow->mpc_map = mpext->mpc_map;
1037         subflow->map_csum_reqd = mpext->csum_reqd;
1038         subflow->map_csum_len = 0;
1039         subflow->map_data_csum = csum_unfold(mpext->csum);
1040
1041         /* Cfr RFC 8684 Section 3.3.0 */
1042         if (unlikely(subflow->map_csum_reqd != csum_reqd))
1043                 return MAPPING_INVALID;
1044
1045         pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
1046                  subflow->map_seq, subflow->map_subflow_seq,
1047                  subflow->map_data_len, subflow->map_csum_reqd,
1048                  subflow->map_data_csum);
1049
1050 validate_seq:
1051         /* we revalidate valid mapping on new skb, because we must ensure
1052          * the current skb is completely covered by the available mapping
1053          */
1054         if (!validate_mapping(ssk, skb)) {
1055                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1056                 return MAPPING_INVALID;
1057         }
1058
1059         skb_ext_del(skb, SKB_EXT_MPTCP);
1060
1061 validate_csum:
1062         return validate_data_csum(ssk, skb, csum_reqd);
1063 }
1064
1065 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1066                                        u64 limit)
1067 {
1068         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1069         bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1070         u32 incr;
1071
1072         incr = limit >= skb->len ? skb->len + fin : limit;
1073
1074         pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
1075                  subflow->map_subflow_seq);
1076         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1077         tcp_sk(ssk)->copied_seq += incr;
1078         if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1079                 sk_eat_skb(ssk, skb);
1080         if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1081                 subflow->map_valid = 0;
1082 }
1083
1084 /* sched mptcp worker to remove the subflow if no more data is pending */
1085 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1086 {
1087         struct sock *sk = (struct sock *)msk;
1088
1089         if (likely(ssk->sk_state != TCP_CLOSE))
1090                 return;
1091
1092         if (skb_queue_empty(&ssk->sk_receive_queue) &&
1093             !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
1094                 sock_hold(sk);
1095                 if (!schedule_work(&msk->work))
1096                         sock_put(sk);
1097         }
1098 }
1099
1100 static bool subflow_check_data_avail(struct sock *ssk)
1101 {
1102         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1103         enum mapping_status status;
1104         struct mptcp_sock *msk;
1105         struct sk_buff *skb;
1106
1107         if (!skb_peek(&ssk->sk_receive_queue))
1108                 WRITE_ONCE(subflow->data_avail, 0);
1109         if (subflow->data_avail)
1110                 return true;
1111
1112         msk = mptcp_sk(subflow->conn);
1113         for (;;) {
1114                 u64 ack_seq;
1115                 u64 old_ack;
1116
1117                 status = get_mapping_status(ssk, msk);
1118                 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1119                 if (unlikely(status == MAPPING_INVALID))
1120                         goto fallback;
1121
1122                 if (unlikely(status == MAPPING_DUMMY))
1123                         goto fallback;
1124
1125                 if (status != MAPPING_OK)
1126                         goto no_data;
1127
1128                 skb = skb_peek(&ssk->sk_receive_queue);
1129                 if (WARN_ON_ONCE(!skb))
1130                         goto no_data;
1131
1132                 /* if msk lacks the remote key, this subflow must provide an
1133                  * MP_CAPABLE-based mapping
1134                  */
1135                 if (unlikely(!READ_ONCE(msk->can_ack))) {
1136                         if (!subflow->mpc_map)
1137                                 goto fallback;
1138                         WRITE_ONCE(msk->remote_key, subflow->remote_key);
1139                         WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1140                         WRITE_ONCE(msk->can_ack, true);
1141                 }
1142
1143                 old_ack = READ_ONCE(msk->ack_seq);
1144                 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1145                 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1146                          ack_seq);
1147                 if (unlikely(before64(ack_seq, old_ack))) {
1148                         mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1149                         continue;
1150                 }
1151
1152                 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1153                 break;
1154         }
1155         return true;
1156
1157 no_data:
1158         subflow_sched_work_if_closed(msk, ssk);
1159         return false;
1160
1161 fallback:
1162         /* RFC 8684 section 3.7. */
1163         if (subflow->mp_join || subflow->fully_established) {
1164                 /* fatal protocol error, close the socket.
1165                  * subflow_error_report() will introduce the appropriate barriers
1166                  */
1167                 ssk->sk_err = EBADMSG;
1168                 tcp_set_state(ssk, TCP_CLOSE);
1169                 subflow->reset_transient = 0;
1170                 subflow->reset_reason = MPTCP_RST_EMPTCP;
1171                 tcp_send_active_reset(ssk, GFP_ATOMIC);
1172                 WRITE_ONCE(subflow->data_avail, 0);
1173                 return false;
1174         }
1175
1176         __mptcp_do_fallback(msk);
1177         skb = skb_peek(&ssk->sk_receive_queue);
1178         subflow->map_valid = 1;
1179         subflow->map_seq = READ_ONCE(msk->ack_seq);
1180         subflow->map_data_len = skb->len;
1181         subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1182         WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
1183         return true;
1184 }
1185
1186 bool mptcp_subflow_data_available(struct sock *sk)
1187 {
1188         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1189
1190         /* check if current mapping is still valid */
1191         if (subflow->map_valid &&
1192             mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1193                 subflow->map_valid = 0;
1194                 WRITE_ONCE(subflow->data_avail, 0);
1195
1196                 pr_debug("Done with mapping: seq=%u data_len=%u",
1197                          subflow->map_subflow_seq,
1198                          subflow->map_data_len);
1199         }
1200
1201         return subflow_check_data_avail(sk);
1202 }
1203
1204 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1205  * not the ssk one.
1206  *
1207  * In mptcp, rwin is about the mptcp-level connection data.
1208  *
1209  * Data that is still on the ssk rx queue can thus be ignored,
1210  * as far as mptcp peer is concerned that data is still inflight.
1211  * DSS ACK is updated when skb is moved to the mptcp rx queue.
1212  */
1213 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1214 {
1215         const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1216         const struct sock *sk = subflow->conn;
1217
1218         *space = __mptcp_space(sk);
1219         *full_space = tcp_full_space(sk);
1220 }
1221
1222 void __mptcp_error_report(struct sock *sk)
1223 {
1224         struct mptcp_subflow_context *subflow;
1225         struct mptcp_sock *msk = mptcp_sk(sk);
1226
1227         mptcp_for_each_subflow(msk, subflow) {
1228                 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1229                 int err = sock_error(ssk);
1230
1231                 if (!err)
1232                         continue;
1233
1234                 /* only propagate errors on fallen-back sockets or
1235                  * on MPC connect
1236                  */
1237                 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1238                         continue;
1239
1240                 inet_sk_state_store(sk, inet_sk_state_load(ssk));
1241                 sk->sk_err = -err;
1242
1243                 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1244                 smp_wmb();
1245                 sk_error_report(sk);
1246                 break;
1247         }
1248 }
1249
1250 static void subflow_error_report(struct sock *ssk)
1251 {
1252         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1253
1254         mptcp_data_lock(sk);
1255         if (!sock_owned_by_user(sk))
1256                 __mptcp_error_report(sk);
1257         else
1258                 set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->flags);
1259         mptcp_data_unlock(sk);
1260 }
1261
1262 static void subflow_data_ready(struct sock *sk)
1263 {
1264         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1265         u16 state = 1 << inet_sk_state_load(sk);
1266         struct sock *parent = subflow->conn;
1267         struct mptcp_sock *msk;
1268
1269         msk = mptcp_sk(parent);
1270         if (state & TCPF_LISTEN) {
1271                 /* MPJ subflow are removed from accept queue before reaching here,
1272                  * avoid stray wakeups
1273                  */
1274                 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1275                         return;
1276
1277                 set_bit(MPTCP_DATA_READY, &msk->flags);
1278                 parent->sk_data_ready(parent);
1279                 return;
1280         }
1281
1282         WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1283                      !subflow->mp_join && !(state & TCPF_CLOSE));
1284
1285         if (mptcp_subflow_data_available(sk))
1286                 mptcp_data_ready(parent, sk);
1287         else if (unlikely(sk->sk_err))
1288                 subflow_error_report(sk);
1289 }
1290
1291 static void subflow_write_space(struct sock *ssk)
1292 {
1293         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1294
1295         mptcp_propagate_sndbuf(sk, ssk);
1296         mptcp_write_space(sk);
1297 }
1298
1299 static struct inet_connection_sock_af_ops *
1300 subflow_default_af_ops(struct sock *sk)
1301 {
1302 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1303         if (sk->sk_family == AF_INET6)
1304                 return &subflow_v6_specific;
1305 #endif
1306         return &subflow_specific;
1307 }
1308
1309 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1310 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1311 {
1312         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1313         struct inet_connection_sock *icsk = inet_csk(sk);
1314         struct inet_connection_sock_af_ops *target;
1315
1316         target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1317
1318         pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1319                  subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1320
1321         if (likely(icsk->icsk_af_ops == target))
1322                 return;
1323
1324         subflow->icsk_af_ops = icsk->icsk_af_ops;
1325         icsk->icsk_af_ops = target;
1326 }
1327 #endif
1328
1329 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1330                          struct sockaddr_storage *addr,
1331                          unsigned short family)
1332 {
1333         memset(addr, 0, sizeof(*addr));
1334         addr->ss_family = family;
1335         if (addr->ss_family == AF_INET) {
1336                 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1337
1338                 if (info->family == AF_INET)
1339                         in_addr->sin_addr = info->addr;
1340 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1341                 else if (ipv6_addr_v4mapped(&info->addr6))
1342                         in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1343 #endif
1344                 in_addr->sin_port = info->port;
1345         }
1346 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1347         else if (addr->ss_family == AF_INET6) {
1348                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1349
1350                 if (info->family == AF_INET)
1351                         ipv6_addr_set_v4mapped(info->addr.s_addr,
1352                                                &in6_addr->sin6_addr);
1353                 else
1354                         in6_addr->sin6_addr = info->addr6;
1355                 in6_addr->sin6_port = info->port;
1356         }
1357 #endif
1358 }
1359
1360 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1361                             const struct mptcp_addr_info *remote,
1362                             u8 flags, int ifindex)
1363 {
1364         struct mptcp_sock *msk = mptcp_sk(sk);
1365         struct mptcp_subflow_context *subflow;
1366         struct sockaddr_storage addr;
1367         int remote_id = remote->id;
1368         int local_id = loc->id;
1369         struct socket *sf;
1370         struct sock *ssk;
1371         u32 remote_token;
1372         int addrlen;
1373         int err;
1374
1375         if (!mptcp_is_fully_established(sk))
1376                 return -ENOTCONN;
1377
1378         err = mptcp_subflow_create_socket(sk, &sf);
1379         if (err)
1380                 return err;
1381
1382         ssk = sf->sk;
1383         subflow = mptcp_subflow_ctx(ssk);
1384         do {
1385                 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1386         } while (!subflow->local_nonce);
1387
1388         if (!local_id) {
1389                 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
1390                 if (err < 0)
1391                         goto failed;
1392
1393                 local_id = err;
1394         }
1395
1396         subflow->remote_key = msk->remote_key;
1397         subflow->local_key = msk->local_key;
1398         subflow->token = msk->token;
1399         mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1400
1401         addrlen = sizeof(struct sockaddr_in);
1402 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1403         if (addr.ss_family == AF_INET6)
1404                 addrlen = sizeof(struct sockaddr_in6);
1405 #endif
1406         ssk->sk_bound_dev_if = ifindex;
1407         err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1408         if (err)
1409                 goto failed;
1410
1411         mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1412         pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1413                  remote_token, local_id, remote_id);
1414         subflow->remote_token = remote_token;
1415         subflow->local_id = local_id;
1416         subflow->remote_id = remote_id;
1417         subflow->request_join = 1;
1418         subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1419         mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1420
1421         mptcp_add_pending_subflow(msk, subflow);
1422         mptcp_sockopt_sync(msk, ssk);
1423         err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1424         if (err && err != -EINPROGRESS)
1425                 goto failed_unlink;
1426
1427         /* discard the subflow socket */
1428         mptcp_sock_graft(ssk, sk->sk_socket);
1429         iput(SOCK_INODE(sf));
1430         return err;
1431
1432 failed_unlink:
1433         spin_lock_bh(&msk->join_list_lock);
1434         list_del(&subflow->node);
1435         spin_unlock_bh(&msk->join_list_lock);
1436         sock_put(mptcp_subflow_tcp_sock(subflow));
1437
1438 failed:
1439         subflow->disposable = 1;
1440         sock_release(sf);
1441         return err;
1442 }
1443
1444 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1445 {
1446 #ifdef CONFIG_SOCK_CGROUP_DATA
1447         struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1448                                 *child_skcd = &child->sk_cgrp_data;
1449
1450         /* only the additional subflows created by kworkers have to be modified */
1451         if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1452             cgroup_id(sock_cgroup_ptr(child_skcd))) {
1453 #ifdef CONFIG_MEMCG
1454                 struct mem_cgroup *memcg = parent->sk_memcg;
1455
1456                 mem_cgroup_sk_free(child);
1457                 if (memcg && css_tryget(&memcg->css))
1458                         child->sk_memcg = memcg;
1459 #endif /* CONFIG_MEMCG */
1460
1461                 cgroup_sk_free(child_skcd);
1462                 *child_skcd = *parent_skcd;
1463                 cgroup_sk_clone(child_skcd);
1464         }
1465 #endif /* CONFIG_SOCK_CGROUP_DATA */
1466 }
1467
1468 static void mptcp_subflow_ops_override(struct sock *ssk)
1469 {
1470 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1471         if (ssk->sk_prot == &tcpv6_prot)
1472                 ssk->sk_prot = &tcpv6_prot_override;
1473         else
1474 #endif
1475                 ssk->sk_prot = &tcp_prot_override;
1476 }
1477
1478 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1479 {
1480 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1481         if (ssk->sk_prot == &tcpv6_prot_override)
1482                 ssk->sk_prot = &tcpv6_prot;
1483         else
1484 #endif
1485                 ssk->sk_prot = &tcp_prot;
1486 }
1487 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
1488 {
1489         struct mptcp_subflow_context *subflow;
1490         struct net *net = sock_net(sk);
1491         struct socket *sf;
1492         int err;
1493
1494         /* un-accepted server sockets can reach here - on bad configuration
1495          * bail early to avoid greater trouble later
1496          */
1497         if (unlikely(!sk->sk_socket))
1498                 return -EINVAL;
1499
1500         err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
1501                                &sf);
1502         if (err)
1503                 return err;
1504
1505         lock_sock(sf->sk);
1506
1507         /* the newly created socket has to be in the same cgroup as its parent */
1508         mptcp_attach_cgroup(sk, sf->sk);
1509
1510         /* kernel sockets do not by default acquire net ref, but TCP timer
1511          * needs it.
1512          */
1513         sf->sk->sk_net_refcnt = 1;
1514         get_net(net);
1515 #ifdef CONFIG_PROC_FS
1516         this_cpu_add(*net->core.sock_inuse, 1);
1517 #endif
1518         err = tcp_set_ulp(sf->sk, "mptcp");
1519         release_sock(sf->sk);
1520
1521         if (err) {
1522                 sock_release(sf);
1523                 return err;
1524         }
1525
1526         /* the newly created socket really belongs to the owning MPTCP master
1527          * socket, even if for additional subflows the allocation is performed
1528          * by a kernel workqueue. Adjust inode references, so that the
1529          * procfs/diag interaces really show this one belonging to the correct
1530          * user.
1531          */
1532         SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1533         SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1534         SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1535
1536         subflow = mptcp_subflow_ctx(sf->sk);
1537         pr_debug("subflow=%p", subflow);
1538
1539         *new_sock = sf;
1540         sock_hold(sk);
1541         subflow->conn = sk;
1542         mptcp_subflow_ops_override(sf->sk);
1543
1544         return 0;
1545 }
1546
1547 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1548                                                         gfp_t priority)
1549 {
1550         struct inet_connection_sock *icsk = inet_csk(sk);
1551         struct mptcp_subflow_context *ctx;
1552
1553         ctx = kzalloc(sizeof(*ctx), priority);
1554         if (!ctx)
1555                 return NULL;
1556
1557         rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1558         INIT_LIST_HEAD(&ctx->node);
1559         INIT_LIST_HEAD(&ctx->delegated_node);
1560
1561         pr_debug("subflow=%p", ctx);
1562
1563         ctx->tcp_sock = sk;
1564
1565         return ctx;
1566 }
1567
1568 static void __subflow_state_change(struct sock *sk)
1569 {
1570         struct socket_wq *wq;
1571
1572         rcu_read_lock();
1573         wq = rcu_dereference(sk->sk_wq);
1574         if (skwq_has_sleeper(wq))
1575                 wake_up_interruptible_all(&wq->wait);
1576         rcu_read_unlock();
1577 }
1578
1579 static bool subflow_is_done(const struct sock *sk)
1580 {
1581         return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1582 }
1583
1584 static void subflow_state_change(struct sock *sk)
1585 {
1586         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1587         struct sock *parent = subflow->conn;
1588
1589         __subflow_state_change(sk);
1590
1591         if (subflow_simultaneous_connect(sk)) {
1592                 mptcp_propagate_sndbuf(parent, sk);
1593                 mptcp_do_fallback(sk);
1594                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1595                 pr_fallback(mptcp_sk(parent));
1596                 subflow->conn_finished = 1;
1597                 mptcp_set_connected(parent);
1598         }
1599
1600         /* as recvmsg() does not acquire the subflow socket for ssk selection
1601          * a fin packet carrying a DSS can be unnoticed if we don't trigger
1602          * the data available machinery here.
1603          */
1604         if (mptcp_subflow_data_available(sk))
1605                 mptcp_data_ready(parent, sk);
1606         else if (unlikely(sk->sk_err))
1607                 subflow_error_report(sk);
1608
1609         subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1610
1611         if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1612             !subflow->rx_eof && subflow_is_done(sk)) {
1613                 subflow->rx_eof = 1;
1614                 mptcp_subflow_eof(parent);
1615         }
1616 }
1617
1618 static int subflow_ulp_init(struct sock *sk)
1619 {
1620         struct inet_connection_sock *icsk = inet_csk(sk);
1621         struct mptcp_subflow_context *ctx;
1622         struct tcp_sock *tp = tcp_sk(sk);
1623         int err = 0;
1624
1625         /* disallow attaching ULP to a socket unless it has been
1626          * created with sock_create_kern()
1627          */
1628         if (!sk->sk_kern_sock) {
1629                 err = -EOPNOTSUPP;
1630                 goto out;
1631         }
1632
1633         ctx = subflow_create_ctx(sk, GFP_KERNEL);
1634         if (!ctx) {
1635                 err = -ENOMEM;
1636                 goto out;
1637         }
1638
1639         pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1640
1641         tp->is_mptcp = 1;
1642         ctx->icsk_af_ops = icsk->icsk_af_ops;
1643         icsk->icsk_af_ops = subflow_default_af_ops(sk);
1644         ctx->tcp_data_ready = sk->sk_data_ready;
1645         ctx->tcp_state_change = sk->sk_state_change;
1646         ctx->tcp_write_space = sk->sk_write_space;
1647         ctx->tcp_error_report = sk->sk_error_report;
1648         sk->sk_data_ready = subflow_data_ready;
1649         sk->sk_write_space = subflow_write_space;
1650         sk->sk_state_change = subflow_state_change;
1651         sk->sk_error_report = subflow_error_report;
1652 out:
1653         return err;
1654 }
1655
1656 static void subflow_ulp_release(struct sock *ssk)
1657 {
1658         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1659         bool release = true;
1660         struct sock *sk;
1661
1662         if (!ctx)
1663                 return;
1664
1665         sk = ctx->conn;
1666         if (sk) {
1667                 /* if the msk has been orphaned, keep the ctx
1668                  * alive, will be freed by __mptcp_close_ssk(),
1669                  * when the subflow is still unaccepted
1670                  */
1671                 release = ctx->disposable || list_empty(&ctx->node);
1672                 sock_put(sk);
1673         }
1674
1675         mptcp_subflow_ops_undo_override(ssk);
1676         if (release)
1677                 kfree_rcu(ctx, rcu);
1678 }
1679
1680 static void subflow_ulp_clone(const struct request_sock *req,
1681                               struct sock *newsk,
1682                               const gfp_t priority)
1683 {
1684         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1685         struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1686         struct mptcp_subflow_context *new_ctx;
1687
1688         if (!tcp_rsk(req)->is_mptcp ||
1689             (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1690                 subflow_ulp_fallback(newsk, old_ctx);
1691                 return;
1692         }
1693
1694         new_ctx = subflow_create_ctx(newsk, priority);
1695         if (!new_ctx) {
1696                 subflow_ulp_fallback(newsk, old_ctx);
1697                 return;
1698         }
1699
1700         new_ctx->conn_finished = 1;
1701         new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1702         new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
1703         new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1704         new_ctx->tcp_write_space = old_ctx->tcp_write_space;
1705         new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1706         new_ctx->rel_write_seq = 1;
1707         new_ctx->tcp_sock = newsk;
1708
1709         if (subflow_req->mp_capable) {
1710                 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1711                  * is fully established only after we receive the remote key
1712                  */
1713                 new_ctx->mp_capable = 1;
1714                 new_ctx->local_key = subflow_req->local_key;
1715                 new_ctx->token = subflow_req->token;
1716                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1717                 new_ctx->idsn = subflow_req->idsn;
1718         } else if (subflow_req->mp_join) {
1719                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1720                 new_ctx->mp_join = 1;
1721                 new_ctx->fully_established = 1;
1722                 new_ctx->backup = subflow_req->backup;
1723                 new_ctx->local_id = subflow_req->local_id;
1724                 new_ctx->remote_id = subflow_req->remote_id;
1725                 new_ctx->token = subflow_req->token;
1726                 new_ctx->thmac = subflow_req->thmac;
1727         }
1728 }
1729
1730 static void tcp_release_cb_override(struct sock *ssk)
1731 {
1732         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1733
1734         if (mptcp_subflow_has_delegated_action(subflow))
1735                 mptcp_subflow_process_delegated(ssk);
1736
1737         tcp_release_cb(ssk);
1738 }
1739
1740 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1741         .name           = "mptcp",
1742         .owner          = THIS_MODULE,
1743         .init           = subflow_ulp_init,
1744         .release        = subflow_ulp_release,
1745         .clone          = subflow_ulp_clone,
1746 };
1747
1748 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1749 {
1750         subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1751         subflow_ops->slab_name = "request_sock_subflow";
1752
1753         subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1754                                               subflow_ops->obj_size, 0,
1755                                               SLAB_ACCOUNT |
1756                                               SLAB_TYPESAFE_BY_RCU,
1757                                               NULL);
1758         if (!subflow_ops->slab)
1759                 return -ENOMEM;
1760
1761         subflow_ops->destructor = subflow_req_destructor;
1762
1763         return 0;
1764 }
1765
1766 void __init mptcp_subflow_init(void)
1767 {
1768         mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
1769         if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
1770                 panic("MPTCP: failed to init subflow request sock ops\n");
1771
1772         subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1773         subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1774
1775         subflow_specific = ipv4_specific;
1776         subflow_specific.conn_request = subflow_v4_conn_request;
1777         subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1778         subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1779
1780         tcp_prot_override = tcp_prot;
1781         tcp_prot_override.release_cb = tcp_release_cb_override;
1782
1783 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1784         subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1785         subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1786
1787         subflow_v6_specific = ipv6_specific;
1788         subflow_v6_specific.conn_request = subflow_v6_conn_request;
1789         subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1790         subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1791
1792         subflow_v6m_specific = subflow_v6_specific;
1793         subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1794         subflow_v6m_specific.send_check = ipv4_specific.send_check;
1795         subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1796         subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1797         subflow_v6m_specific.net_frag_header_len = 0;
1798
1799         tcpv6_prot_override = tcpv6_prot;
1800         tcpv6_prot_override.release_cb = tcp_release_cb_override;
1801 #endif
1802
1803         mptcp_diag_subflow_init(&subflow_ulp_ops);
1804
1805         if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1806                 panic("MPTCP: failed to register subflows to ULP\n");
1807 }