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 static void mptcp_subflow_ops_undo_override(struct sock *ssk);
  29
  30 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
  31                                   enum linux_mptcp_mib_field field)
  32 {
  33         MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
  34 }
  35
  36 static void subflow_req_destructor(struct request_sock *req)
  37 {
  38         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
  39
  40         pr_debug("subflow_req=%p", subflow_req);
  41
  42         if (subflow_req->msk)
  43                 sock_put((struct sock *)subflow_req->msk);
  44
  45         mptcp_token_destroy_request(req);
  46         tcp_request_sock_ops.destructor(req);
  47 }
  48
  49 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
  50                                   void *hmac)
  51 {
  52         u8 msg[8];
  53
  54         put_unaligned_be32(nonce1, &msg[0]);
  55         put_unaligned_be32(nonce2, &msg[4]);
  56
  57         mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
  58 }
  59
  60 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
  61 {
  62         return mptcp_is_fully_established((void *)msk) &&
  63                READ_ONCE(msk->pm.accept_subflow);
  64 }
  65
  66 /* validate received token and create truncated hmac and nonce for SYN-ACK */
  67 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
  68 {
  69         struct mptcp_sock *msk = subflow_req->msk;
  70         u8 hmac[SHA256_DIGEST_SIZE];
  71
  72         get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
  73
  74         subflow_generate_hmac(msk->local_key, msk->remote_key,
  75                               subflow_req->local_nonce,
  76                               subflow_req->remote_nonce, hmac);
  77
  78         subflow_req->thmac = get_unaligned_be64(hmac);
  79 }
  80
  81 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
  82 {
  83         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
  84         struct mptcp_sock *msk;
  85         int local_id;
  86
  87         msk = mptcp_token_get_sock(subflow_req->token);
  88         if (!msk) {
  89                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
  90                 return NULL;
  91         }
  92
  93         local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
  94         if (local_id < 0) {
  95                 sock_put((struct sock *)msk);
  96                 return NULL;
  97         }
  98         subflow_req->local_id = local_id;
  99
 100         return msk;
 101 }
 102
 103 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
 104 {
 105         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 106
 107         subflow_req->mp_capable = 0;
 108         subflow_req->mp_join = 0;
 109         subflow_req->msk = NULL;
 110         mptcp_token_init_request(req);
 111 }
 112
 113 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
 114 {
 115         return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
 116 }
 117
 118 /* Init mptcp request socket.
 119  *
 120  * Returns an error code if a JOIN has failed and a TCP reset
 121  * should be sent.
 122  */
 123 static int subflow_check_req(struct request_sock *req,
 124                              const struct sock *sk_listener,
 125                              struct sk_buff *skb)
 126 {
 127         struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 128         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 129         struct mptcp_options_received mp_opt;
 130
 131         pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
 132
 133 #ifdef CONFIG_TCP_MD5SIG
 134         /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
 135          * TCP option space.
 136          */
 137         if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
 138                 return -EINVAL;
 139 #endif
 140
 141         mptcp_get_options(skb, &mp_opt);
 142
 143         if (mp_opt.mp_capable) {
 144                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
 145
 146                 if (mp_opt.mp_join)
 147                         return 0;
 148         } else if (mp_opt.mp_join) {
 149                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
 150         }
 151
 152         if (mp_opt.mp_capable && listener->request_mptcp) {
 153                 int err, retries = 4;
 154
 155                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 156 again:
 157                 do {
 158                         get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
 159                 } while (subflow_req->local_key == 0);
 160
 161                 if (unlikely(req->syncookie)) {
 162                         mptcp_crypto_key_sha(subflow_req->local_key,
 163                                              &subflow_req->token,
 164                                              &subflow_req->idsn);
 165                         if (mptcp_token_exists(subflow_req->token)) {
 166                                 if (retries-- > 0)
 167                                         goto again;
 168                         } else {
 169                                 subflow_req->mp_capable = 1;
 170                         }
 171                         return 0;
 172                 }
 173
 174                 err = mptcp_token_new_request(req);
 175                 if (err == 0)
 176                         subflow_req->mp_capable = 1;
 177                 else if (retries-- > 0)
 178                         goto again;
 179
 180         } else if (mp_opt.mp_join && listener->request_mptcp) {
 181                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 182                 subflow_req->mp_join = 1;
 183                 subflow_req->backup = mp_opt.backup;
 184                 subflow_req->remote_id = mp_opt.join_id;
 185                 subflow_req->token = mp_opt.token;
 186                 subflow_req->remote_nonce = mp_opt.nonce;
 187                 subflow_req->msk = subflow_token_join_request(req);
 188
 189                 /* Can't fall back to TCP in this case. */
 190                 if (!subflow_req->msk)
 191                         return -EPERM;
 192
 193                 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
 194                         pr_debug("syn inet_sport=%d %d",
 195                                  ntohs(inet_sk(sk_listener)->inet_sport),
 196                                  ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
 197                         if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
 198                                 sock_put((struct sock *)subflow_req->msk);
 199                                 mptcp_token_destroy_request(req);
 200                                 tcp_request_sock_ops.destructor(req);
 201                                 subflow_req->msk = NULL;
 202                                 subflow_req->mp_join = 0;
 203                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
 204                                 return -EPERM;
 205                         }
 206                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
 207                 }
 208
 209                 subflow_req_create_thmac(subflow_req);
 210
 211                 if (unlikely(req->syncookie)) {
 212                         if (mptcp_can_accept_new_subflow(subflow_req->msk))
 213                                 subflow_init_req_cookie_join_save(subflow_req, skb);
 214                 }
 215
 216                 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
 217                          subflow_req->remote_nonce, subflow_req->msk);
 218         }
 219
 220         return 0;
 221 }
 222
 223 int mptcp_subflow_init_cookie_req(struct request_sock *req,
 224                                   const struct sock *sk_listener,
 225                                   struct sk_buff *skb)
 226 {
 227         struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 228         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 229         struct mptcp_options_received mp_opt;
 230         int err;
 231
 232         subflow_init_req(req, sk_listener);
 233         mptcp_get_options(skb, &mp_opt);
 234
 235         if (mp_opt.mp_capable && mp_opt.mp_join)
 236                 return -EINVAL;
 237
 238         if (mp_opt.mp_capable && listener->request_mptcp) {
 239                 if (mp_opt.sndr_key == 0)
 240                         return -EINVAL;
 241
 242                 subflow_req->local_key = mp_opt.rcvr_key;
 243                 err = mptcp_token_new_request(req);
 244                 if (err)
 245                         return err;
 246
 247                 subflow_req->mp_capable = 1;
 248                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 249         } else if (mp_opt.mp_join && listener->request_mptcp) {
 250                 if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
 251                         return -EINVAL;
 252
 253                 if (mptcp_can_accept_new_subflow(subflow_req->msk))
 254                         subflow_req->mp_join = 1;
 255
 256                 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 257         }
 258
 259         return 0;
 260 }
 261 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
 262
 263 static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
 264                                               struct sk_buff *skb,
 265                                               struct flowi *fl,
 266                                               struct request_sock *req)
 267 {
 268         struct dst_entry *dst;
 269         int err;
 270
 271         tcp_rsk(req)->is_mptcp = 1;
 272         subflow_init_req(req, sk);
 273
 274         dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req);
 275         if (!dst)
 276                 return NULL;
 277
 278         err = subflow_check_req(req, sk, skb);
 279         if (err == 0)
 280                 return dst;
 281
 282         dst_release(dst);
 283         if (!req->syncookie)
 284                 tcp_request_sock_ops.send_reset(sk, skb);
 285         return NULL;
 286 }
 287
 288 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 289 static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
 290                                               struct sk_buff *skb,
 291                                               struct flowi *fl,
 292                                               struct request_sock *req)
 293 {
 294         struct dst_entry *dst;
 295         int err;
 296
 297         tcp_rsk(req)->is_mptcp = 1;
 298         subflow_init_req(req, sk);
 299
 300         dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req);
 301         if (!dst)
 302                 return NULL;
 303
 304         err = subflow_check_req(req, sk, skb);
 305         if (err == 0)
 306                 return dst;
 307
 308         dst_release(dst);
 309         if (!req->syncookie)
 310                 tcp6_request_sock_ops.send_reset(sk, skb);
 311         return NULL;
 312 }
 313 #endif
 314
 315 /* validate received truncated hmac and create hmac for third ACK */
 316 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
 317 {
 318         u8 hmac[SHA256_DIGEST_SIZE];
 319         u64 thmac;
 320
 321         subflow_generate_hmac(subflow->remote_key, subflow->local_key,
 322                               subflow->remote_nonce, subflow->local_nonce,
 323                               hmac);
 324
 325         thmac = get_unaligned_be64(hmac);
 326         pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
 327                  subflow, subflow->token,
 328                  (unsigned long long)thmac,
 329                  (unsigned long long)subflow->thmac);
 330
 331         return thmac == subflow->thmac;
 332 }
 333
 334 void mptcp_subflow_reset(struct sock *ssk)
 335 {
 336         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 337         struct sock *sk = subflow->conn;
 338
 339         /* must hold: tcp_done() could drop last reference on parent */
 340         sock_hold(sk);
 341
 342         tcp_set_state(ssk, TCP_CLOSE);
 343         tcp_send_active_reset(ssk, GFP_ATOMIC);
 344         tcp_done(ssk);
 345         if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
 346             schedule_work(&mptcp_sk(sk)->work))
 347                 return; /* worker will put sk for us */
 348
 349         sock_put(sk);
 350 }
 351
 352 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
 353 {
 354         return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
 355 }
 356
 357 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 358 {
 359         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 360         struct mptcp_options_received mp_opt;
 361         struct sock *parent = subflow->conn;
 362
 363         subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 364
 365         if (inet_sk_state_load(parent) == TCP_SYN_SENT) {
 366                 inet_sk_state_store(parent, TCP_ESTABLISHED);
 367                 parent->sk_state_change(parent);
 368         }
 369
 370         /* be sure no special action on any packet other than syn-ack */
 371         if (subflow->conn_finished)
 372                 return;
 373
 374         mptcp_propagate_sndbuf(parent, sk);
 375         subflow->rel_write_seq = 1;
 376         subflow->conn_finished = 1;
 377         subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
 378         pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
 379
 380         mptcp_get_options(skb, &mp_opt);
 381         if (subflow->request_mptcp) {
 382                 if (!mp_opt.mp_capable) {
 383                         MPTCP_INC_STATS(sock_net(sk),
 384                                         MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
 385                         mptcp_do_fallback(sk);
 386                         pr_fallback(mptcp_sk(subflow->conn));
 387                         goto fallback;
 388                 }
 389
 390                 subflow->mp_capable = 1;
 391                 subflow->can_ack = 1;
 392                 subflow->remote_key = mp_opt.sndr_key;
 393                 pr_debug("subflow=%p, remote_key=%llu", subflow,
 394                          subflow->remote_key);
 395                 mptcp_finish_connect(sk);
 396         } else if (subflow->request_join) {
 397                 u8 hmac[SHA256_DIGEST_SIZE];
 398
 399                 if (!mp_opt.mp_join)
 400                         goto do_reset;
 401
 402                 subflow->thmac = mp_opt.thmac;
 403                 subflow->remote_nonce = mp_opt.nonce;
 404                 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
 405                          subflow->thmac, subflow->remote_nonce);
 406
 407                 if (!subflow_thmac_valid(subflow)) {
 408                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
 409                         goto do_reset;
 410                 }
 411
 412                 subflow_generate_hmac(subflow->local_key, subflow->remote_key,
 413                                       subflow->local_nonce,
 414                                       subflow->remote_nonce,
 415                                       hmac);
 416                 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
 417
 418                 if (!mptcp_finish_join(sk))
 419                         goto do_reset;
 420
 421                 subflow->mp_join = 1;
 422                 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
 423
 424                 if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
 425                         pr_debug("synack inet_dport=%d %d",
 426                                  ntohs(inet_sk(sk)->inet_dport),
 427                                  ntohs(inet_sk(parent)->inet_dport));
 428                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
 429                 }
 430         } else if (mptcp_check_fallback(sk)) {
 431 fallback:
 432                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
 433         }
 434         return;
 435
 436 do_reset:
 437         mptcp_subflow_reset(sk);
 438 }
 439
 440 struct request_sock_ops mptcp_subflow_request_sock_ops;
 441 EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops);
 442 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
 443
 444 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 445 {
 446         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 447
 448         pr_debug("subflow=%p", subflow);
 449
 450         /* Never answer to SYNs sent to broadcast or multicast */
 451         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 452                 goto drop;
 453
 454         return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 455                                 &subflow_request_sock_ipv4_ops,
 456                                 sk, skb);
 457 drop:
 458         tcp_listendrop(sk);
 459         return 0;
 460 }
 461
 462 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 463 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
 464 static struct inet_connection_sock_af_ops subflow_v6_specific;
 465 static struct inet_connection_sock_af_ops subflow_v6m_specific;
 466 static struct proto tcpv6_prot_override;
 467
 468 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 469 {
 470         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 471
 472         pr_debug("subflow=%p", subflow);
 473
 474         if (skb->protocol == htons(ETH_P_IP))
 475                 return subflow_v4_conn_request(sk, skb);
 476
 477         if (!ipv6_unicast_destination(skb))
 478                 goto drop;
 479
 480         return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 481                                 &subflow_request_sock_ipv6_ops, sk, skb);
 482
 483 drop:
 484         tcp_listendrop(sk);
 485         return 0; /* don't send reset */
 486 }
 487 #endif
 488
 489 /* validate hmac received in third ACK */
 490 static bool subflow_hmac_valid(const struct request_sock *req,
 491                                const struct mptcp_options_received *mp_opt)
 492 {
 493         const struct mptcp_subflow_request_sock *subflow_req;
 494         u8 hmac[SHA256_DIGEST_SIZE];
 495         struct mptcp_sock *msk;
 496
 497         subflow_req = mptcp_subflow_rsk(req);
 498         msk = subflow_req->msk;
 499         if (!msk)
 500                 return false;
 501
 502         subflow_generate_hmac(msk->remote_key, msk->local_key,
 503                               subflow_req->remote_nonce,
 504                               subflow_req->local_nonce, hmac);
 505
 506         return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
 507 }
 508
 509 static void mptcp_sock_destruct(struct sock *sk)
 510 {
 511         /* if new mptcp socket isn't accepted, it is free'd
 512          * from the tcp listener sockets request queue, linked
 513          * from req->sk.  The tcp socket is released.
 514          * This calls the ULP release function which will
 515          * also remove the mptcp socket, via
 516          * sock_put(ctx->conn).
 517          *
 518          * Problem is that the mptcp socket will be in
 519          * ESTABLISHED state and will not have the SOCK_DEAD flag.
 520          * Both result in warnings from inet_sock_destruct.
 521          */
 522
 523         if (sk->sk_state == TCP_ESTABLISHED) {
 524                 sk->sk_state = TCP_CLOSE;
 525                 WARN_ON_ONCE(sk->sk_socket);
 526                 sock_orphan(sk);
 527         }
 528
 529         mptcp_destroy_common(mptcp_sk(sk));
 530         inet_sock_destruct(sk);
 531 }
 532
 533 static void mptcp_force_close(struct sock *sk)
 534 {
 535         inet_sk_state_store(sk, TCP_CLOSE);
 536         sk_common_release(sk);
 537 }
 538
 539 static void subflow_ulp_fallback(struct sock *sk,
 540                                  struct mptcp_subflow_context *old_ctx)
 541 {
 542         struct inet_connection_sock *icsk = inet_csk(sk);
 543
 544         mptcp_subflow_tcp_fallback(sk, old_ctx);
 545         icsk->icsk_ulp_ops = NULL;
 546         rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
 547         tcp_sk(sk)->is_mptcp = 0;
 548
 549         mptcp_subflow_ops_undo_override(sk);
 550 }
 551
 552 static void subflow_drop_ctx(struct sock *ssk)
 553 {
 554         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
 555
 556         if (!ctx)
 557                 return;
 558
 559         subflow_ulp_fallback(ssk, ctx);
 560         if (ctx->conn)
 561                 sock_put(ctx->conn);
 562
 563         kfree_rcu(ctx, rcu);
 564 }
 565
 566 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 567                                      struct mptcp_options_received *mp_opt)
 568 {
 569         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 570
 571         subflow->remote_key = mp_opt->sndr_key;
 572         subflow->fully_established = 1;
 573         subflow->can_ack = 1;
 574         WRITE_ONCE(msk->fully_established, true);
 575 }
 576
 577 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 578                                           struct sk_buff *skb,
 579                                           struct request_sock *req,
 580                                           struct dst_entry *dst,
 581                                           struct request_sock *req_unhash,
 582                                           bool *own_req)
 583 {
 584         struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
 585         struct mptcp_subflow_request_sock *subflow_req;
 586         struct mptcp_options_received mp_opt;
 587         bool fallback, fallback_is_fatal;
 588         struct sock *new_msk = NULL;
 589         struct sock *child;
 590
 591         pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
 592
 593         /* After child creation we must look for 'mp_capable' even when options
 594          * are not parsed
 595          */
 596         mp_opt.mp_capable = 0;
 597
 598         /* hopefully temporary handling for MP_JOIN+syncookie */
 599         subflow_req = mptcp_subflow_rsk(req);
 600         fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
 601         fallback = !tcp_rsk(req)->is_mptcp;
 602         if (fallback)
 603                 goto create_child;
 604
 605         /* if the sk is MP_CAPABLE, we try to fetch the client key */
 606         if (subflow_req->mp_capable) {
 607                 if (TCP_SKB_CB(skb)->seq != subflow_req->ssn_offset + 1) {
 608                         /* here we can receive and accept an in-window,
 609                          * out-of-order pkt, which will not carry the MP_CAPABLE
 610                          * opt even on mptcp enabled paths
 611                          */
 612                         goto create_msk;
 613                 }
 614
 615                 mptcp_get_options(skb, &mp_opt);
 616                 if (!mp_opt.mp_capable) {
 617                         fallback = true;
 618                         goto create_child;
 619                 }
 620
 621 create_msk:
 622                 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
 623                 if (!new_msk)
 624                         fallback = true;
 625         } else if (subflow_req->mp_join) {
 626                 mptcp_get_options(skb, &mp_opt);
 627                 if (!mp_opt.mp_join || !subflow_hmac_valid(req, &mp_opt) ||
 628                     !mptcp_can_accept_new_subflow(subflow_req->msk)) {
 629                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
 630                         fallback = true;
 631                 }
 632         }
 633
 634 create_child:
 635         child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
 636                                                      req_unhash, own_req);
 637
 638         if (child && *own_req) {
 639                 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
 640
 641                 tcp_rsk(req)->drop_req = false;
 642
 643                 /* we need to fallback on ctx allocation failure and on pre-reqs
 644                  * checking above. In the latter scenario we additionally need
 645                  * to reset the context to non MPTCP status.
 646                  */
 647                 if (!ctx || fallback) {
 648                         if (fallback_is_fatal)
 649                                 goto dispose_child;
 650
 651                         subflow_drop_ctx(child);
 652                         goto out;
 653                 }
 654
 655                 if (ctx->mp_capable) {
 656                         /* this can't race with mptcp_close(), as the msk is
 657                          * not yet exposted to user-space
 658                          */
 659                         inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
 660
 661                         /* record the newly created socket as the first msk
 662                          * subflow, but don't link it yet into conn_list
 663                          */
 664                         WRITE_ONCE(mptcp_sk(new_msk)->first, child);
 665
 666                         /* new mpc subflow takes ownership of the newly
 667                          * created mptcp socket
 668                          */
 669                         new_msk->sk_destruct = mptcp_sock_destruct;
 670                         mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
 671                         mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
 672                         ctx->conn = new_msk;
 673                         new_msk = NULL;
 674
 675                         /* with OoO packets we can reach here without ingress
 676                          * mpc option
 677                          */
 678                         if (mp_opt.mp_capable)
 679                                 mptcp_subflow_fully_established(ctx, &mp_opt);
 680                 } else if (ctx->mp_join) {
 681                         struct mptcp_sock *owner;
 682
 683                         owner = subflow_req->msk;
 684                         if (!owner)
 685                                 goto dispose_child;
 686
 687                         /* move the msk reference ownership to the subflow */
 688                         subflow_req->msk = NULL;
 689                         ctx->conn = (struct sock *)owner;
 690                         if (!mptcp_finish_join(child))
 691                                 goto dispose_child;
 692
 693                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
 694                         tcp_rsk(req)->drop_req = true;
 695
 696                         if (subflow_use_different_sport(owner, sk)) {
 697                                 pr_debug("ack inet_sport=%d %d",
 698                                          ntohs(inet_sk(sk)->inet_sport),
 699                                          ntohs(inet_sk((struct sock *)owner)->inet_sport));
 700                                 if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
 701                                         SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
 702                                         goto out;
 703                                 }
 704                                 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
 705                         }
 706                 }
 707         }
 708
 709 out:
 710         /* dispose of the left over mptcp master, if any */
 711         if (unlikely(new_msk))
 712                 mptcp_force_close(new_msk);
 713
 714         /* check for expected invariant - should never trigger, just help
 715          * catching eariler subtle bugs
 716          */
 717         WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
 718                      (!mptcp_subflow_ctx(child) ||
 719                       !mptcp_subflow_ctx(child)->conn));
 720         return child;
 721
 722 dispose_child:
 723         subflow_drop_ctx(child);
 724         tcp_rsk(req)->drop_req = true;
 725         inet_csk_prepare_for_destroy_sock(child);
 726         tcp_done(child);
 727         req->rsk_ops->send_reset(sk, skb);
 728
 729         /* The last child reference will be released by the caller */
 730         return child;
 731 }
 732
 733 static struct inet_connection_sock_af_ops subflow_specific;
 734 static struct proto tcp_prot_override;
 735
 736 enum mapping_status {
 737         MAPPING_OK,
 738         MAPPING_INVALID,
 739         MAPPING_EMPTY,
 740         MAPPING_DATA_FIN,
 741         MAPPING_DUMMY
 742 };
 743
 744 static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq)
 745 {
 746         if ((u32)seq == (u32)old_seq)
 747                 return old_seq;
 748
 749         /* Assume map covers data not mapped yet. */
 750         return seq | ((old_seq + old_data_len + 1) & GENMASK_ULL(63, 32));
 751 }
 752
 753 static void warn_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
 754 {
 755         WARN_ONCE(1, "Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
 756                   ssn, subflow->map_subflow_seq, subflow->map_data_len);
 757 }
 758
 759 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
 760 {
 761         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 762         unsigned int skb_consumed;
 763
 764         skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
 765         if (WARN_ON_ONCE(skb_consumed >= skb->len))
 766                 return true;
 767
 768         return skb->len - skb_consumed <= subflow->map_data_len -
 769                                           mptcp_subflow_get_map_offset(subflow);
 770 }
 771
 772 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
 773 {
 774         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 775         u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
 776
 777         if (unlikely(before(ssn, subflow->map_subflow_seq))) {
 778                 /* Mapping covers data later in the subflow stream,
 779                  * currently unsupported.
 780                  */
 781                 warn_bad_map(subflow, ssn);
 782                 return false;
 783         }
 784         if (unlikely(!before(ssn, subflow->map_subflow_seq +
 785                                   subflow->map_data_len))) {
 786                 /* Mapping does covers past subflow data, invalid */
 787                 warn_bad_map(subflow, ssn + skb->len);
 788                 return false;
 789         }
 790         return true;
 791 }
 792
 793 static enum mapping_status get_mapping_status(struct sock *ssk,
 794                                               struct mptcp_sock *msk)
 795 {
 796         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 797         struct mptcp_ext *mpext;
 798         struct sk_buff *skb;
 799         u16 data_len;
 800         u64 map_seq;
 801
 802         skb = skb_peek(&ssk->sk_receive_queue);
 803         if (!skb)
 804                 return MAPPING_EMPTY;
 805
 806         if (mptcp_check_fallback(ssk))
 807                 return MAPPING_DUMMY;
 808
 809         mpext = mptcp_get_ext(skb);
 810         if (!mpext || !mpext->use_map) {
 811                 if (!subflow->map_valid && !skb->len) {
 812                         /* the TCP stack deliver 0 len FIN pkt to the receive
 813                          * queue, that is the only 0len pkts ever expected here,
 814                          * and we can admit no mapping only for 0 len pkts
 815                          */
 816                         if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
 817                                 WARN_ONCE(1, "0len seq %d:%d flags %x",
 818                                           TCP_SKB_CB(skb)->seq,
 819                                           TCP_SKB_CB(skb)->end_seq,
 820                                           TCP_SKB_CB(skb)->tcp_flags);
 821                         sk_eat_skb(ssk, skb);
 822                         return MAPPING_EMPTY;
 823                 }
 824
 825                 if (!subflow->map_valid)
 826                         return MAPPING_INVALID;
 827
 828                 goto validate_seq;
 829         }
 830
 831         pr_debug("seq=%llu is64=%d ssn=%u data_len=%u data_fin=%d",
 832                  mpext->data_seq, mpext->dsn64, mpext->subflow_seq,
 833                  mpext->data_len, mpext->data_fin);
 834
 835         data_len = mpext->data_len;
 836         if (data_len == 0) {
 837                 pr_err("Infinite mapping not handled");
 838                 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
 839                 return MAPPING_INVALID;
 840         }
 841
 842         if (mpext->data_fin == 1) {
 843                 if (data_len == 1) {
 844                         bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
 845                                                                  mpext->dsn64);
 846                         pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
 847                         if (subflow->map_valid) {
 848                                 /* A DATA_FIN might arrive in a DSS
 849                                  * option before the previous mapping
 850                                  * has been fully consumed. Continue
 851                                  * handling the existing mapping.
 852                                  */
 853                                 skb_ext_del(skb, SKB_EXT_MPTCP);
 854                                 return MAPPING_OK;
 855                         } else {
 856                                 if (updated && schedule_work(&msk->work))
 857                                         sock_hold((struct sock *)msk);
 858
 859                                 return MAPPING_DATA_FIN;
 860                         }
 861                 } else {
 862                         u64 data_fin_seq = mpext->data_seq + data_len - 1;
 863
 864                         /* If mpext->data_seq is a 32-bit value, data_fin_seq
 865                          * must also be limited to 32 bits.
 866                          */
 867                         if (!mpext->dsn64)
 868                                 data_fin_seq &= GENMASK_ULL(31, 0);
 869
 870                         mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
 871                         pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d",
 872                                  data_fin_seq, mpext->dsn64);
 873                 }
 874
 875                 /* Adjust for DATA_FIN using 1 byte of sequence space */
 876                 data_len--;
 877         }
 878
 879         if (!mpext->dsn64) {
 880                 map_seq = expand_seq(subflow->map_seq, subflow->map_data_len,
 881                                      mpext->data_seq);
 882                 pr_debug("expanded seq=%llu", subflow->map_seq);
 883         } else {
 884                 map_seq = mpext->data_seq;
 885         }
 886         WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
 887
 888         if (subflow->map_valid) {
 889                 /* Allow replacing only with an identical map */
 890                 if (subflow->map_seq == map_seq &&
 891                     subflow->map_subflow_seq == mpext->subflow_seq &&
 892                     subflow->map_data_len == data_len) {
 893                         skb_ext_del(skb, SKB_EXT_MPTCP);
 894                         return MAPPING_OK;
 895                 }
 896
 897                 /* If this skb data are fully covered by the current mapping,
 898                  * the new map would need caching, which is not supported
 899                  */
 900                 if (skb_is_fully_mapped(ssk, skb)) {
 901                         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
 902                         return MAPPING_INVALID;
 903                 }
 904
 905                 /* will validate the next map after consuming the current one */
 906                 return MAPPING_OK;
 907         }
 908
 909         subflow->map_seq = map_seq;
 910         subflow->map_subflow_seq = mpext->subflow_seq;
 911         subflow->map_data_len = data_len;
 912         subflow->map_valid = 1;
 913         subflow->mpc_map = mpext->mpc_map;
 914         pr_debug("new map seq=%llu subflow_seq=%u data_len=%u",
 915                  subflow->map_seq, subflow->map_subflow_seq,
 916                  subflow->map_data_len);
 917
 918 validate_seq:
 919         /* we revalidate valid mapping on new skb, because we must ensure
 920          * the current skb is completely covered by the available mapping
 921          */
 922         if (!validate_mapping(ssk, skb))
 923                 return MAPPING_INVALID;
 924
 925         skb_ext_del(skb, SKB_EXT_MPTCP);
 926         return MAPPING_OK;
 927 }
 928
 929 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
 930                                        u64 limit)
 931 {
 932         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 933         bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
 934         u32 incr;
 935
 936         incr = limit >= skb->len ? skb->len + fin : limit;
 937
 938         pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
 939                  subflow->map_subflow_seq);
 940         MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
 941         tcp_sk(ssk)->copied_seq += incr;
 942         if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
 943                 sk_eat_skb(ssk, skb);
 944         if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
 945                 subflow->map_valid = 0;
 946 }
 947
 948 /* sched mptcp worker to remove the subflow if no more data is pending */
 949 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
 950 {
 951         struct sock *sk = (struct sock *)msk;
 952
 953         if (likely(ssk->sk_state != TCP_CLOSE))
 954                 return;
 955
 956         if (skb_queue_empty(&ssk->sk_receive_queue) &&
 957             !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
 958                 sock_hold(sk);
 959                 if (!schedule_work(&msk->work))
 960                         sock_put(sk);
 961         }
 962 }
 963
 964 static bool subflow_check_data_avail(struct sock *ssk)
 965 {
 966         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 967         enum mapping_status status;
 968         struct mptcp_sock *msk;
 969         struct sk_buff *skb;
 970
 971         pr_debug("msk=%p ssk=%p data_avail=%d skb=%p", subflow->conn, ssk,
 972                  subflow->data_avail, skb_peek(&ssk->sk_receive_queue));
 973         if (!skb_peek(&ssk->sk_receive_queue))
 974                 subflow->data_avail = 0;
 975         if (subflow->data_avail)
 976                 return true;
 977
 978         msk = mptcp_sk(subflow->conn);
 979         for (;;) {
 980                 u64 ack_seq;
 981                 u64 old_ack;
 982
 983                 status = get_mapping_status(ssk, msk);
 984                 pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status);
 985                 if (status == MAPPING_INVALID) {
 986                         ssk->sk_err = EBADMSG;
 987                         goto fatal;
 988                 }
 989                 if (status == MAPPING_DUMMY) {
 990                         __mptcp_do_fallback(msk);
 991                         skb = skb_peek(&ssk->sk_receive_queue);
 992                         subflow->map_valid = 1;
 993                         subflow->map_seq = READ_ONCE(msk->ack_seq);
 994                         subflow->map_data_len = skb->len;
 995                         subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq -
 996                                                    subflow->ssn_offset;
 997                         subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
 998                         return true;
 999                 }
1000
1001                 if (status != MAPPING_OK)
1002                         goto no_data;
1003
1004                 skb = skb_peek(&ssk->sk_receive_queue);
1005                 if (WARN_ON_ONCE(!skb))
1006                         goto no_data;
1007
1008                 /* if msk lacks the remote key, this subflow must provide an
1009                  * MP_CAPABLE-based mapping
1010                  */
1011                 if (unlikely(!READ_ONCE(msk->can_ack))) {
1012                         if (!subflow->mpc_map) {
1013                                 ssk->sk_err = EBADMSG;
1014                                 goto fatal;
1015                         }
1016                         WRITE_ONCE(msk->remote_key, subflow->remote_key);
1017                         WRITE_ONCE(msk->ack_seq, subflow->map_seq);
1018                         WRITE_ONCE(msk->can_ack, true);
1019                 }
1020
1021                 old_ack = READ_ONCE(msk->ack_seq);
1022                 ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1023                 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
1024                          ack_seq);
1025                 if (ack_seq == old_ack) {
1026                         subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
1027                         break;
1028                 } else if (after64(ack_seq, old_ack)) {
1029                         subflow->data_avail = MPTCP_SUBFLOW_OOO_DATA;
1030                         break;
1031                 }
1032
1033                 /* only accept in-sequence mapping. Old values are spurious
1034                  * retransmission
1035                  */
1036                 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1037         }
1038         return true;
1039
1040 no_data:
1041         subflow_sched_work_if_closed(msk, ssk);
1042         return false;
1043 fatal:
1044         /* fatal protocol error, close the socket */
1045         /* This barrier is coupled with smp_rmb() in tcp_poll() */
1046         smp_wmb();
1047         ssk->sk_error_report(ssk);
1048         tcp_set_state(ssk, TCP_CLOSE);
1049         tcp_send_active_reset(ssk, GFP_ATOMIC);
1050         subflow->data_avail = 0;
1051         return false;
1052 }
1053
1054 bool mptcp_subflow_data_available(struct sock *sk)
1055 {
1056         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1057
1058         /* check if current mapping is still valid */
1059         if (subflow->map_valid &&
1060             mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1061                 subflow->map_valid = 0;
1062                 subflow->data_avail = 0;
1063
1064                 pr_debug("Done with mapping: seq=%u data_len=%u",
1065                          subflow->map_subflow_seq,
1066                          subflow->map_data_len);
1067         }
1068
1069         return subflow_check_data_avail(sk);
1070 }
1071
1072 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1073  * not the ssk one.
1074  *
1075  * In mptcp, rwin is about the mptcp-level connection data.
1076  *
1077  * Data that is still on the ssk rx queue can thus be ignored,
1078  * as far as mptcp peer is concerened that data is still inflight.
1079  * DSS ACK is updated when skb is moved to the mptcp rx queue.
1080  */
1081 void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1082 {
1083         const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1084         const struct sock *sk = subflow->conn;
1085
1086         *space = __mptcp_space(sk);
1087         *full_space = tcp_full_space(sk);
1088 }
1089
1090 static void subflow_data_ready(struct sock *sk)
1091 {
1092         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1093         u16 state = 1 << inet_sk_state_load(sk);
1094         struct sock *parent = subflow->conn;
1095         struct mptcp_sock *msk;
1096
1097         msk = mptcp_sk(parent);
1098         if (state & TCPF_LISTEN) {
1099                 set_bit(MPTCP_DATA_READY, &msk->flags);
1100                 parent->sk_data_ready(parent);
1101                 return;
1102         }
1103
1104         WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1105                      !subflow->mp_join && !(state & TCPF_CLOSE));
1106
1107         if (mptcp_subflow_data_available(sk))
1108                 mptcp_data_ready(parent, sk);
1109 }
1110
1111 static void subflow_write_space(struct sock *ssk)
1112 {
1113         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1114
1115         mptcp_propagate_sndbuf(sk, ssk);
1116         mptcp_write_space(sk);
1117 }
1118
1119 void __mptcp_error_report(struct sock *sk)
1120 {
1121         struct mptcp_subflow_context *subflow;
1122         struct mptcp_sock *msk = mptcp_sk(sk);
1123
1124         mptcp_for_each_subflow(msk, subflow) {
1125                 struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
1126                 int err = sock_error(ssk);
1127
1128                 if (!err)
1129                         continue;
1130
1131                 /* only propagate errors on fallen-back sockets or
1132                  * on MPC connect
1133                  */
1134                 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
1135                         continue;
1136
1137                 inet_sk_state_store(sk, inet_sk_state_load(ssk));
1138                 sk->sk_err = -err;
1139
1140                 /* This barrier is coupled with smp_rmb() in mptcp_poll() */
1141                 smp_wmb();
1142                 sk->sk_error_report(sk);
1143                 break;
1144         }
1145 }
1146
1147 static void subflow_error_report(struct sock *ssk)
1148 {
1149         struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1150
1151         mptcp_data_lock(sk);
1152         if (!sock_owned_by_user(sk))
1153                 __mptcp_error_report(sk);
1154         else
1155                 set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->flags);
1156         mptcp_data_unlock(sk);
1157 }
1158
1159 static struct inet_connection_sock_af_ops *
1160 subflow_default_af_ops(struct sock *sk)
1161 {
1162 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1163         if (sk->sk_family == AF_INET6)
1164                 return &subflow_v6_specific;
1165 #endif
1166         return &subflow_specific;
1167 }
1168
1169 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1170 void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1171 {
1172         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1173         struct inet_connection_sock *icsk = inet_csk(sk);
1174         struct inet_connection_sock_af_ops *target;
1175
1176         target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1177
1178         pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
1179                  subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1180
1181         if (likely(icsk->icsk_af_ops == target))
1182                 return;
1183
1184         subflow->icsk_af_ops = icsk->icsk_af_ops;
1185         icsk->icsk_af_ops = target;
1186 }
1187 #endif
1188
1189 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1190                          struct sockaddr_storage *addr,
1191                          unsigned short family)
1192 {
1193         memset(addr, 0, sizeof(*addr));
1194         addr->ss_family = family;
1195         if (addr->ss_family == AF_INET) {
1196                 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1197
1198                 if (info->family == AF_INET)
1199                         in_addr->sin_addr = info->addr;
1200 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1201                 else if (ipv6_addr_v4mapped(&info->addr6))
1202                         in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1203 #endif
1204                 in_addr->sin_port = info->port;
1205         }
1206 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1207         else if (addr->ss_family == AF_INET6) {
1208                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1209
1210                 if (info->family == AF_INET)
1211                         ipv6_addr_set_v4mapped(info->addr.s_addr,
1212                                                &in6_addr->sin6_addr);
1213                 else
1214                         in6_addr->sin6_addr = info->addr6;
1215                 in6_addr->sin6_port = info->port;
1216         }
1217 #endif
1218 }
1219
1220 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
1221                             const struct mptcp_addr_info *remote)
1222 {
1223         struct mptcp_sock *msk = mptcp_sk(sk);
1224         struct mptcp_subflow_context *subflow;
1225         struct sockaddr_storage addr;
1226         int remote_id = remote->id;
1227         int local_id = loc->id;
1228         struct socket *sf;
1229         struct sock *ssk;
1230         u32 remote_token;
1231         int addrlen;
1232         int err;
1233
1234         if (!mptcp_is_fully_established(sk))
1235                 return -ENOTCONN;
1236
1237         err = mptcp_subflow_create_socket(sk, &sf);
1238         if (err)
1239                 return err;
1240
1241         ssk = sf->sk;
1242         subflow = mptcp_subflow_ctx(ssk);
1243         do {
1244                 get_random_bytes(&subflow->local_nonce, sizeof(u32));
1245         } while (!subflow->local_nonce);
1246
1247         if (!local_id) {
1248                 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
1249                 if (err < 0)
1250                         goto failed;
1251
1252                 local_id = err;
1253         }
1254
1255         subflow->remote_key = msk->remote_key;
1256         subflow->local_key = msk->local_key;
1257         subflow->token = msk->token;
1258         mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
1259
1260         addrlen = sizeof(struct sockaddr_in);
1261 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1262         if (addr.ss_family == AF_INET6)
1263                 addrlen = sizeof(struct sockaddr_in6);
1264 #endif
1265         ssk->sk_bound_dev_if = loc->ifindex;
1266         err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1267         if (err)
1268                 goto failed;
1269
1270         mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1271         pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk,
1272                  remote_token, local_id, remote_id);
1273         subflow->remote_token = remote_token;
1274         subflow->local_id = local_id;
1275         subflow->remote_id = remote_id;
1276         subflow->request_join = 1;
1277         subflow->request_bkup = !!(loc->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1278         mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1279
1280         mptcp_add_pending_subflow(msk, subflow);
1281         err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1282         if (err && err != -EINPROGRESS)
1283                 goto failed_unlink;
1284
1285         /* discard the subflow socket */
1286         mptcp_sock_graft(ssk, sk->sk_socket);
1287         iput(SOCK_INODE(sf));
1288         return err;
1289
1290 failed_unlink:
1291         spin_lock_bh(&msk->join_list_lock);
1292         list_del(&subflow->node);
1293         spin_unlock_bh(&msk->join_list_lock);
1294
1295 failed:
1296         subflow->disposable = 1;
1297         sock_release(sf);
1298         return err;
1299 }
1300
1301 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1302 {
1303 #ifdef CONFIG_SOCK_CGROUP_DATA
1304         struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1305                                 *child_skcd = &child->sk_cgrp_data;
1306
1307         /* only the additional subflows created by kworkers have to be modified */
1308         if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1309             cgroup_id(sock_cgroup_ptr(child_skcd))) {
1310 #ifdef CONFIG_MEMCG
1311                 struct mem_cgroup *memcg = parent->sk_memcg;
1312
1313                 mem_cgroup_sk_free(child);
1314                 if (memcg && css_tryget(&memcg->css))
1315                         child->sk_memcg = memcg;
1316 #endif /* CONFIG_MEMCG */
1317
1318                 cgroup_sk_free(child_skcd);
1319                 *child_skcd = *parent_skcd;
1320                 cgroup_sk_clone(child_skcd);
1321         }
1322 #endif /* CONFIG_SOCK_CGROUP_DATA */
1323 }
1324
1325 static void mptcp_subflow_ops_override(struct sock *ssk)
1326 {
1327 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1328         if (ssk->sk_prot == &tcpv6_prot)
1329                 ssk->sk_prot = &tcpv6_prot_override;
1330         else
1331 #endif
1332                 ssk->sk_prot = &tcp_prot_override;
1333 }
1334
1335 static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1336 {
1337 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1338         if (ssk->sk_prot == &tcpv6_prot_override)
1339                 ssk->sk_prot = &tcpv6_prot;
1340         else
1341 #endif
1342                 ssk->sk_prot = &tcp_prot;
1343 }
1344 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
1345 {
1346         struct mptcp_subflow_context *subflow;
1347         struct net *net = sock_net(sk);
1348         struct socket *sf;
1349         int err;
1350
1351         /* un-accepted server sockets can reach here - on bad configuration
1352          * bail early to avoid greater trouble later
1353          */
1354         if (unlikely(!sk->sk_socket))
1355                 return -EINVAL;
1356
1357         err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
1358                                &sf);
1359         if (err)
1360                 return err;
1361
1362         lock_sock(sf->sk);
1363
1364         /* the newly created socket has to be in the same cgroup as its parent */
1365         mptcp_attach_cgroup(sk, sf->sk);
1366
1367         /* kernel sockets do not by default acquire net ref, but TCP timer
1368          * needs it.
1369          */
1370         sf->sk->sk_net_refcnt = 1;
1371         get_net(net);
1372 #ifdef CONFIG_PROC_FS
1373         this_cpu_add(*net->core.sock_inuse, 1);
1374 #endif
1375         err = tcp_set_ulp(sf->sk, "mptcp");
1376         release_sock(sf->sk);
1377
1378         if (err) {
1379                 sock_release(sf);
1380                 return err;
1381         }
1382
1383         /* the newly created socket really belongs to the owning MPTCP master
1384          * socket, even if for additional subflows the allocation is performed
1385          * by a kernel workqueue. Adjust inode references, so that the
1386          * procfs/diag interaces really show this one belonging to the correct
1387          * user.
1388          */
1389         SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1390         SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1391         SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1392
1393         subflow = mptcp_subflow_ctx(sf->sk);
1394         pr_debug("subflow=%p", subflow);
1395
1396         *new_sock = sf;
1397         sock_hold(sk);
1398         subflow->conn = sk;
1399         mptcp_subflow_ops_override(sf->sk);
1400
1401         return 0;
1402 }
1403
1404 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1405                                                         gfp_t priority)
1406 {
1407         struct inet_connection_sock *icsk = inet_csk(sk);
1408         struct mptcp_subflow_context *ctx;
1409
1410         ctx = kzalloc(sizeof(*ctx), priority);
1411         if (!ctx)
1412                 return NULL;
1413
1414         rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1415         INIT_LIST_HEAD(&ctx->node);
1416         INIT_LIST_HEAD(&ctx->delegated_node);
1417
1418         pr_debug("subflow=%p", ctx);
1419
1420         ctx->tcp_sock = sk;
1421
1422         return ctx;
1423 }
1424
1425 static void __subflow_state_change(struct sock *sk)
1426 {
1427         struct socket_wq *wq;
1428
1429         rcu_read_lock();
1430         wq = rcu_dereference(sk->sk_wq);
1431         if (skwq_has_sleeper(wq))
1432                 wake_up_interruptible_all(&wq->wait);
1433         rcu_read_unlock();
1434 }
1435
1436 static bool subflow_is_done(const struct sock *sk)
1437 {
1438         return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1439 }
1440
1441 static void subflow_state_change(struct sock *sk)
1442 {
1443         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1444         struct sock *parent = subflow->conn;
1445
1446         __subflow_state_change(sk);
1447
1448         if (subflow_simultaneous_connect(sk)) {
1449                 mptcp_propagate_sndbuf(parent, sk);
1450                 mptcp_do_fallback(sk);
1451                 mptcp_rcv_space_init(mptcp_sk(parent), sk);
1452                 pr_fallback(mptcp_sk(parent));
1453                 subflow->conn_finished = 1;
1454                 if (inet_sk_state_load(parent) == TCP_SYN_SENT) {
1455                         inet_sk_state_store(parent, TCP_ESTABLISHED);
1456                         parent->sk_state_change(parent);
1457                 }
1458         }
1459
1460         /* as recvmsg() does not acquire the subflow socket for ssk selection
1461          * a fin packet carrying a DSS can be unnoticed if we don't trigger
1462          * the data available machinery here.
1463          */
1464         if (mptcp_subflow_data_available(sk))
1465                 mptcp_data_ready(parent, sk);
1466
1467         subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1468
1469         if (__mptcp_check_fallback(mptcp_sk(parent)) &&
1470             !subflow->rx_eof && subflow_is_done(sk)) {
1471                 subflow->rx_eof = 1;
1472                 mptcp_subflow_eof(parent);
1473         }
1474 }
1475
1476 static int subflow_ulp_init(struct sock *sk)
1477 {
1478         struct inet_connection_sock *icsk = inet_csk(sk);
1479         struct mptcp_subflow_context *ctx;
1480         struct tcp_sock *tp = tcp_sk(sk);
1481         int err = 0;
1482
1483         /* disallow attaching ULP to a socket unless it has been
1484          * created with sock_create_kern()
1485          */
1486         if (!sk->sk_kern_sock) {
1487                 err = -EOPNOTSUPP;
1488                 goto out;
1489         }
1490
1491         ctx = subflow_create_ctx(sk, GFP_KERNEL);
1492         if (!ctx) {
1493                 err = -ENOMEM;
1494                 goto out;
1495         }
1496
1497         pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
1498
1499         tp->is_mptcp = 1;
1500         ctx->icsk_af_ops = icsk->icsk_af_ops;
1501         icsk->icsk_af_ops = subflow_default_af_ops(sk);
1502         ctx->tcp_data_ready = sk->sk_data_ready;
1503         ctx->tcp_state_change = sk->sk_state_change;
1504         ctx->tcp_write_space = sk->sk_write_space;
1505         ctx->tcp_error_report = sk->sk_error_report;
1506         sk->sk_data_ready = subflow_data_ready;
1507         sk->sk_write_space = subflow_write_space;
1508         sk->sk_state_change = subflow_state_change;
1509         sk->sk_error_report = subflow_error_report;
1510 out:
1511         return err;
1512 }
1513
1514 static void subflow_ulp_release(struct sock *ssk)
1515 {
1516         struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1517         bool release = true;
1518         struct sock *sk;
1519
1520         if (!ctx)
1521                 return;
1522
1523         sk = ctx->conn;
1524         if (sk) {
1525                 /* if the msk has been orphaned, keep the ctx
1526                  * alive, will be freed by __mptcp_close_ssk(),
1527                  * when the subflow is still unaccepted
1528                  */
1529                 release = ctx->disposable || list_empty(&ctx->node);
1530                 sock_put(sk);
1531         }
1532
1533         mptcp_subflow_ops_undo_override(ssk);
1534         if (release)
1535                 kfree_rcu(ctx, rcu);
1536 }
1537
1538 static void subflow_ulp_clone(const struct request_sock *req,
1539                               struct sock *newsk,
1540                               const gfp_t priority)
1541 {
1542         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
1543         struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
1544         struct mptcp_subflow_context *new_ctx;
1545
1546         if (!tcp_rsk(req)->is_mptcp ||
1547             (!subflow_req->mp_capable && !subflow_req->mp_join)) {
1548                 subflow_ulp_fallback(newsk, old_ctx);
1549                 return;
1550         }
1551
1552         new_ctx = subflow_create_ctx(newsk, priority);
1553         if (!new_ctx) {
1554                 subflow_ulp_fallback(newsk, old_ctx);
1555                 return;
1556         }
1557
1558         new_ctx->conn_finished = 1;
1559         new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
1560         new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
1561         new_ctx->tcp_state_change = old_ctx->tcp_state_change;
1562         new_ctx->tcp_write_space = old_ctx->tcp_write_space;
1563         new_ctx->tcp_error_report = old_ctx->tcp_error_report;
1564         new_ctx->rel_write_seq = 1;
1565         new_ctx->tcp_sock = newsk;
1566
1567         if (subflow_req->mp_capable) {
1568                 /* see comments in subflow_syn_recv_sock(), MPTCP connection
1569                  * is fully established only after we receive the remote key
1570                  */
1571                 new_ctx->mp_capable = 1;
1572                 new_ctx->local_key = subflow_req->local_key;
1573                 new_ctx->token = subflow_req->token;
1574                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1575                 new_ctx->idsn = subflow_req->idsn;
1576         } else if (subflow_req->mp_join) {
1577                 new_ctx->ssn_offset = subflow_req->ssn_offset;
1578                 new_ctx->mp_join = 1;
1579                 new_ctx->fully_established = 1;
1580                 new_ctx->backup = subflow_req->backup;
1581                 new_ctx->local_id = subflow_req->local_id;
1582                 new_ctx->remote_id = subflow_req->remote_id;
1583                 new_ctx->token = subflow_req->token;
1584                 new_ctx->thmac = subflow_req->thmac;
1585         }
1586 }
1587
1588 static void tcp_release_cb_override(struct sock *ssk)
1589 {
1590         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1591
1592         if (mptcp_subflow_has_delegated_action(subflow))
1593                 mptcp_subflow_process_delegated(ssk);
1594
1595         tcp_release_cb(ssk);
1596 }
1597
1598 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
1599         .name           = "mptcp",
1600         .owner          = THIS_MODULE,
1601         .init           = subflow_ulp_init,
1602         .release        = subflow_ulp_release,
1603         .clone          = subflow_ulp_clone,
1604 };
1605
1606 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
1607 {
1608         subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
1609         subflow_ops->slab_name = "request_sock_subflow";
1610
1611         subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
1612                                               subflow_ops->obj_size, 0,
1613                                               SLAB_ACCOUNT |
1614                                               SLAB_TYPESAFE_BY_RCU,
1615                                               NULL);
1616         if (!subflow_ops->slab)
1617                 return -ENOMEM;
1618
1619         subflow_ops->destructor = subflow_req_destructor;
1620
1621         return 0;
1622 }
1623
1624 void __init mptcp_subflow_init(void)
1625 {
1626         mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
1627         if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
1628                 panic("MPTCP: failed to init subflow request sock ops\n");
1629
1630         subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
1631         subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
1632
1633         subflow_specific = ipv4_specific;
1634         subflow_specific.conn_request = subflow_v4_conn_request;
1635         subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
1636         subflow_specific.sk_rx_dst_set = subflow_finish_connect;
1637
1638         tcp_prot_override = tcp_prot;
1639         tcp_prot_override.release_cb = tcp_release_cb_override;
1640
1641 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1642         subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
1643         subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
1644
1645         subflow_v6_specific = ipv6_specific;
1646         subflow_v6_specific.conn_request = subflow_v6_conn_request;
1647         subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
1648         subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
1649
1650         subflow_v6m_specific = subflow_v6_specific;
1651         subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
1652         subflow_v6m_specific.send_check = ipv4_specific.send_check;
1653         subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
1654         subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
1655         subflow_v6m_specific.net_frag_header_len = 0;
1656
1657         tcpv6_prot_override = tcpv6_prot;
1658         tcpv6_prot_override.release_cb = tcp_release_cb_override;
1659 #endif
1660
1661         mptcp_diag_subflow_init(&subflow_ulp_ops);
1662
1663         if (tcp_register_ulp(&subflow_ulp_ops) != 0)
1664                 panic("MPTCP: failed to register subflows to ULP\n");
1665 }