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/sha2.h> 13 #include <crypto/utils.h> 14 #include <net/sock.h> 15 #include <net/inet_common.h> 16 #include <net/inet_hashtables.h> 17 #include <net/protocol.h> 18 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 19 #include <net/ip6_route.h> 20 #include <net/transp_v6.h> 21 #endif 22 #include <net/mptcp.h> 23 #include "protocol.h" 24 #include "mib.h" 25 26 #include <trace/events/mptcp.h> 27 #include <trace/events/sock.h> 28 29 static void mptcp_subflow_ops_undo_override(struct sock *ssk); 30 31 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req, 32 enum linux_mptcp_mib_field field) 33 { 34 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field); 35 } 36 37 static void subflow_req_destructor(struct request_sock *req) 38 { 39 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 40 41 pr_debug("subflow_req=%p", subflow_req); 42 43 if (subflow_req->msk) 44 sock_put((struct sock *)subflow_req->msk); 45 46 mptcp_token_destroy_request(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 ((mptcp_pm_is_userspace(msk) && 64 mptcp_userspace_pm_active(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(READ_ONCE(msk->local_key), 77 READ_ONCE(msk->remote_key), 78 subflow_req->local_nonce, 79 subflow_req->remote_nonce, hmac); 80 81 subflow_req->thmac = get_unaligned_be64(hmac); 82 } 83 84 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req) 85 { 86 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 87 struct mptcp_sock *msk; 88 int local_id; 89 90 msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token); 91 if (!msk) { 92 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN); 93 return NULL; 94 } 95 96 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req); 97 if (local_id < 0) { 98 sock_put((struct sock *)msk); 99 return NULL; 100 } 101 subflow_req->local_id = local_id; 102 103 return msk; 104 } 105 106 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener) 107 { 108 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 109 110 subflow_req->mp_capable = 0; 111 subflow_req->mp_join = 0; 112 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener)); 113 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener)); 114 subflow_req->msk = NULL; 115 mptcp_token_init_request(req); 116 } 117 118 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk) 119 { 120 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport; 121 } 122 123 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason) 124 { 125 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 126 127 if (mpext) { 128 memset(mpext, 0, sizeof(*mpext)); 129 mpext->reset_reason = reason; 130 } 131 } 132 133 /* Init mptcp request socket. 134 * 135 * Returns an error code if a JOIN has failed and a TCP reset 136 * should be sent. 137 */ 138 static int subflow_check_req(struct request_sock *req, 139 const struct sock *sk_listener, 140 struct sk_buff *skb) 141 { 142 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 143 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 144 struct mptcp_options_received mp_opt; 145 bool opt_mp_capable, opt_mp_join; 146 147 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener); 148 149 #ifdef CONFIG_TCP_MD5SIG 150 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of 151 * TCP option space. 152 */ 153 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) 154 return -EINVAL; 155 #endif 156 157 mptcp_get_options(skb, &mp_opt); 158 159 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN); 160 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN); 161 if (opt_mp_capable) { 162 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE); 163 164 if (opt_mp_join) 165 return 0; 166 } else if (opt_mp_join) { 167 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX); 168 } 169 170 if (opt_mp_capable && listener->request_mptcp) { 171 int err, retries = MPTCP_TOKEN_MAX_RETRIES; 172 173 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 174 again: 175 do { 176 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key)); 177 } while (subflow_req->local_key == 0); 178 179 if (unlikely(req->syncookie)) { 180 mptcp_crypto_key_sha(subflow_req->local_key, 181 &subflow_req->token, 182 &subflow_req->idsn); 183 if (mptcp_token_exists(subflow_req->token)) { 184 if (retries-- > 0) 185 goto again; 186 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT); 187 } else { 188 subflow_req->mp_capable = 1; 189 } 190 return 0; 191 } 192 193 err = mptcp_token_new_request(req); 194 if (err == 0) 195 subflow_req->mp_capable = 1; 196 else if (retries-- > 0) 197 goto again; 198 else 199 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT); 200 201 } else if (opt_mp_join && listener->request_mptcp) { 202 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 203 subflow_req->mp_join = 1; 204 subflow_req->backup = mp_opt.backup; 205 subflow_req->remote_id = mp_opt.join_id; 206 subflow_req->token = mp_opt.token; 207 subflow_req->remote_nonce = mp_opt.nonce; 208 subflow_req->msk = subflow_token_join_request(req); 209 210 /* Can't fall back to TCP in this case. */ 211 if (!subflow_req->msk) { 212 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); 213 return -EPERM; 214 } 215 216 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) { 217 pr_debug("syn inet_sport=%d %d", 218 ntohs(inet_sk(sk_listener)->inet_sport), 219 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport)); 220 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) { 221 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX); 222 return -EPERM; 223 } 224 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX); 225 } 226 227 subflow_req_create_thmac(subflow_req); 228 229 if (unlikely(req->syncookie)) { 230 if (mptcp_can_accept_new_subflow(subflow_req->msk)) 231 subflow_init_req_cookie_join_save(subflow_req, skb); 232 else 233 return -EPERM; 234 } 235 236 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token, 237 subflow_req->remote_nonce, subflow_req->msk); 238 } 239 240 return 0; 241 } 242 243 int mptcp_subflow_init_cookie_req(struct request_sock *req, 244 const struct sock *sk_listener, 245 struct sk_buff *skb) 246 { 247 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 248 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 249 struct mptcp_options_received mp_opt; 250 bool opt_mp_capable, opt_mp_join; 251 int err; 252 253 subflow_init_req(req, sk_listener); 254 mptcp_get_options(skb, &mp_opt); 255 256 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK); 257 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK); 258 if (opt_mp_capable && opt_mp_join) 259 return -EINVAL; 260 261 if (opt_mp_capable && listener->request_mptcp) { 262 if (mp_opt.sndr_key == 0) 263 return -EINVAL; 264 265 subflow_req->local_key = mp_opt.rcvr_key; 266 err = mptcp_token_new_request(req); 267 if (err) 268 return err; 269 270 subflow_req->mp_capable = 1; 271 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 272 } else if (opt_mp_join && listener->request_mptcp) { 273 if (!mptcp_token_join_cookie_init_state(subflow_req, skb)) 274 return -EINVAL; 275 276 subflow_req->mp_join = 1; 277 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 278 } 279 280 return 0; 281 } 282 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req); 283 284 static struct dst_entry *subflow_v4_route_req(const struct sock *sk, 285 struct sk_buff *skb, 286 struct flowi *fl, 287 struct request_sock *req) 288 { 289 struct dst_entry *dst; 290 int err; 291 292 tcp_rsk(req)->is_mptcp = 1; 293 subflow_init_req(req, sk); 294 295 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req); 296 if (!dst) 297 return NULL; 298 299 err = subflow_check_req(req, sk, skb); 300 if (err == 0) 301 return dst; 302 303 dst_release(dst); 304 if (!req->syncookie) 305 tcp_request_sock_ops.send_reset(sk, skb); 306 return NULL; 307 } 308 309 static void subflow_prep_synack(const struct sock *sk, struct request_sock *req, 310 struct tcp_fastopen_cookie *foc, 311 enum tcp_synack_type synack_type) 312 { 313 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 314 struct inet_request_sock *ireq = inet_rsk(req); 315 316 /* clear tstamp_ok, as needed depending on cookie */ 317 if (foc && foc->len > -1) 318 ireq->tstamp_ok = 0; 319 320 if (synack_type == TCP_SYNACK_FASTOPEN) 321 mptcp_fastopen_subflow_synack_set_params(subflow, req); 322 } 323 324 static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst, 325 struct flowi *fl, 326 struct request_sock *req, 327 struct tcp_fastopen_cookie *foc, 328 enum tcp_synack_type synack_type, 329 struct sk_buff *syn_skb) 330 { 331 subflow_prep_synack(sk, req, foc, synack_type); 332 333 return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc, 334 synack_type, syn_skb); 335 } 336 337 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 338 static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst, 339 struct flowi *fl, 340 struct request_sock *req, 341 struct tcp_fastopen_cookie *foc, 342 enum tcp_synack_type synack_type, 343 struct sk_buff *syn_skb) 344 { 345 subflow_prep_synack(sk, req, foc, synack_type); 346 347 return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc, 348 synack_type, syn_skb); 349 } 350 351 static struct dst_entry *subflow_v6_route_req(const struct sock *sk, 352 struct sk_buff *skb, 353 struct flowi *fl, 354 struct request_sock *req) 355 { 356 struct dst_entry *dst; 357 int err; 358 359 tcp_rsk(req)->is_mptcp = 1; 360 subflow_init_req(req, sk); 361 362 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req); 363 if (!dst) 364 return NULL; 365 366 err = subflow_check_req(req, sk, skb); 367 if (err == 0) 368 return dst; 369 370 dst_release(dst); 371 if (!req->syncookie) 372 tcp6_request_sock_ops.send_reset(sk, skb); 373 return NULL; 374 } 375 #endif 376 377 /* validate received truncated hmac and create hmac for third ACK */ 378 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow) 379 { 380 u8 hmac[SHA256_DIGEST_SIZE]; 381 u64 thmac; 382 383 subflow_generate_hmac(subflow->remote_key, subflow->local_key, 384 subflow->remote_nonce, subflow->local_nonce, 385 hmac); 386 387 thmac = get_unaligned_be64(hmac); 388 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n", 389 subflow, subflow->token, thmac, subflow->thmac); 390 391 return thmac == subflow->thmac; 392 } 393 394 void mptcp_subflow_reset(struct sock *ssk) 395 { 396 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 397 struct sock *sk = subflow->conn; 398 399 /* mptcp_mp_fail_no_response() can reach here on an already closed 400 * socket 401 */ 402 if (ssk->sk_state == TCP_CLOSE) 403 return; 404 405 /* must hold: tcp_done() could drop last reference on parent */ 406 sock_hold(sk); 407 408 tcp_send_active_reset(ssk, GFP_ATOMIC); 409 tcp_done(ssk); 410 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags)) 411 mptcp_schedule_work(sk); 412 413 sock_put(sk); 414 } 415 416 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk) 417 { 418 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport; 419 } 420 421 void __mptcp_sync_state(struct sock *sk, int state) 422 { 423 struct mptcp_subflow_context *subflow; 424 struct mptcp_sock *msk = mptcp_sk(sk); 425 struct sock *ssk = msk->first; 426 427 subflow = mptcp_subflow_ctx(ssk); 428 __mptcp_propagate_sndbuf(sk, ssk); 429 if (!msk->rcvspace_init) 430 mptcp_rcv_space_init(msk, ssk); 431 432 if (sk->sk_state == TCP_SYN_SENT) { 433 /* subflow->idsn is always available is TCP_SYN_SENT state, 434 * even for the FASTOPEN scenarios 435 */ 436 WRITE_ONCE(msk->write_seq, subflow->idsn + 1); 437 WRITE_ONCE(msk->snd_nxt, msk->write_seq); 438 mptcp_set_state(sk, state); 439 sk->sk_state_change(sk); 440 } 441 } 442 443 static void subflow_set_remote_key(struct mptcp_sock *msk, 444 struct mptcp_subflow_context *subflow, 445 const struct mptcp_options_received *mp_opt) 446 { 447 /* active MPC subflow will reach here multiple times: 448 * at subflow_finish_connect() time and at 4th ack time 449 */ 450 if (subflow->remote_key_valid) 451 return; 452 453 subflow->remote_key_valid = 1; 454 subflow->remote_key = mp_opt->sndr_key; 455 mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn); 456 subflow->iasn++; 457 458 WRITE_ONCE(msk->remote_key, subflow->remote_key); 459 WRITE_ONCE(msk->ack_seq, subflow->iasn); 460 WRITE_ONCE(msk->can_ack, true); 461 atomic64_set(&msk->rcv_wnd_sent, subflow->iasn); 462 } 463 464 static void mptcp_propagate_state(struct sock *sk, struct sock *ssk, 465 struct mptcp_subflow_context *subflow, 466 const struct mptcp_options_received *mp_opt) 467 { 468 struct mptcp_sock *msk = mptcp_sk(sk); 469 470 mptcp_data_lock(sk); 471 if (mp_opt) { 472 /* Options are available only in the non fallback cases 473 * avoid updating rx path fields otherwise 474 */ 475 WRITE_ONCE(msk->snd_una, subflow->idsn + 1); 476 WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd); 477 subflow_set_remote_key(msk, subflow, mp_opt); 478 } 479 480 if (!sock_owned_by_user(sk)) { 481 __mptcp_sync_state(sk, ssk->sk_state); 482 } else { 483 msk->pending_state = ssk->sk_state; 484 __set_bit(MPTCP_SYNC_STATE, &msk->cb_flags); 485 } 486 mptcp_data_unlock(sk); 487 } 488 489 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 490 { 491 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 492 struct mptcp_options_received mp_opt; 493 struct sock *parent = subflow->conn; 494 struct mptcp_sock *msk; 495 496 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb); 497 498 /* be sure no special action on any packet other than syn-ack */ 499 if (subflow->conn_finished) 500 return; 501 502 msk = mptcp_sk(parent); 503 subflow->rel_write_seq = 1; 504 subflow->conn_finished = 1; 505 subflow->ssn_offset = TCP_SKB_CB(skb)->seq; 506 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset); 507 508 mptcp_get_options(skb, &mp_opt); 509 if (subflow->request_mptcp) { 510 if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) { 511 MPTCP_INC_STATS(sock_net(sk), 512 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); 513 mptcp_do_fallback(sk); 514 pr_fallback(msk); 515 goto fallback; 516 } 517 518 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD) 519 WRITE_ONCE(msk->csum_enabled, true); 520 if (mp_opt.deny_join_id0) 521 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 522 subflow->mp_capable = 1; 523 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK); 524 mptcp_finish_connect(sk); 525 mptcp_propagate_state(parent, sk, subflow, &mp_opt); 526 } else if (subflow->request_join) { 527 u8 hmac[SHA256_DIGEST_SIZE]; 528 529 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) { 530 subflow->reset_reason = MPTCP_RST_EMPTCP; 531 goto do_reset; 532 } 533 534 subflow->backup = mp_opt.backup; 535 subflow->thmac = mp_opt.thmac; 536 subflow->remote_nonce = mp_opt.nonce; 537 WRITE_ONCE(subflow->remote_id, mp_opt.join_id); 538 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d", 539 subflow, subflow->thmac, subflow->remote_nonce, 540 subflow->backup); 541 542 if (!subflow_thmac_valid(subflow)) { 543 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC); 544 subflow->reset_reason = MPTCP_RST_EMPTCP; 545 goto do_reset; 546 } 547 548 if (!mptcp_finish_join(sk)) 549 goto do_reset; 550 551 subflow_generate_hmac(subflow->local_key, subflow->remote_key, 552 subflow->local_nonce, 553 subflow->remote_nonce, 554 hmac); 555 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN); 556 557 subflow->mp_join = 1; 558 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX); 559 560 if (subflow_use_different_dport(msk, sk)) { 561 pr_debug("synack inet_dport=%d %d", 562 ntohs(inet_sk(sk)->inet_dport), 563 ntohs(inet_sk(parent)->inet_dport)); 564 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX); 565 } 566 } else if (mptcp_check_fallback(sk)) { 567 fallback: 568 mptcp_propagate_state(parent, sk, subflow, NULL); 569 } 570 return; 571 572 do_reset: 573 subflow->reset_transient = 0; 574 mptcp_subflow_reset(sk); 575 } 576 577 static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id) 578 { 579 WARN_ON_ONCE(local_id < 0 || local_id > 255); 580 WRITE_ONCE(subflow->local_id, local_id); 581 } 582 583 static int subflow_chk_local_id(struct sock *sk) 584 { 585 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 586 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 587 int err; 588 589 if (likely(subflow->local_id >= 0)) 590 return 0; 591 592 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk); 593 if (err < 0) 594 return err; 595 596 subflow_set_local_id(subflow, err); 597 return 0; 598 } 599 600 static int subflow_rebuild_header(struct sock *sk) 601 { 602 int err = subflow_chk_local_id(sk); 603 604 if (unlikely(err < 0)) 605 return err; 606 607 return inet_sk_rebuild_header(sk); 608 } 609 610 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 611 static int subflow_v6_rebuild_header(struct sock *sk) 612 { 613 int err = subflow_chk_local_id(sk); 614 615 if (unlikely(err < 0)) 616 return err; 617 618 return inet6_sk_rebuild_header(sk); 619 } 620 #endif 621 622 static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init; 623 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init; 624 625 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb) 626 { 627 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 628 629 pr_debug("subflow=%p", subflow); 630 631 /* Never answer to SYNs sent to broadcast or multicast */ 632 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 633 goto drop; 634 635 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops, 636 &subflow_request_sock_ipv4_ops, 637 sk, skb); 638 drop: 639 tcp_listendrop(sk); 640 return 0; 641 } 642 643 static void subflow_v4_req_destructor(struct request_sock *req) 644 { 645 subflow_req_destructor(req); 646 tcp_request_sock_ops.destructor(req); 647 } 648 649 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 650 static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init; 651 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init; 652 static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init; 653 static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init; 654 static struct proto tcpv6_prot_override __ro_after_init; 655 656 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb) 657 { 658 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 659 660 pr_debug("subflow=%p", subflow); 661 662 if (skb->protocol == htons(ETH_P_IP)) 663 return subflow_v4_conn_request(sk, skb); 664 665 if (!ipv6_unicast_destination(skb)) 666 goto drop; 667 668 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) { 669 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS); 670 return 0; 671 } 672 673 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops, 674 &subflow_request_sock_ipv6_ops, sk, skb); 675 676 drop: 677 tcp_listendrop(sk); 678 return 0; /* don't send reset */ 679 } 680 681 static void subflow_v6_req_destructor(struct request_sock *req) 682 { 683 subflow_req_destructor(req); 684 tcp6_request_sock_ops.destructor(req); 685 } 686 #endif 687 688 struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops, 689 struct sock *sk_listener, 690 bool attach_listener) 691 { 692 if (ops->family == AF_INET) 693 ops = &mptcp_subflow_v4_request_sock_ops; 694 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 695 else if (ops->family == AF_INET6) 696 ops = &mptcp_subflow_v6_request_sock_ops; 697 #endif 698 699 return inet_reqsk_alloc(ops, sk_listener, attach_listener); 700 } 701 EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc); 702 703 /* validate hmac received in third ACK */ 704 static bool subflow_hmac_valid(const struct request_sock *req, 705 const struct mptcp_options_received *mp_opt) 706 { 707 const struct mptcp_subflow_request_sock *subflow_req; 708 u8 hmac[SHA256_DIGEST_SIZE]; 709 struct mptcp_sock *msk; 710 711 subflow_req = mptcp_subflow_rsk(req); 712 msk = subflow_req->msk; 713 if (!msk) 714 return false; 715 716 subflow_generate_hmac(READ_ONCE(msk->remote_key), 717 READ_ONCE(msk->local_key), 718 subflow_req->remote_nonce, 719 subflow_req->local_nonce, hmac); 720 721 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN); 722 } 723 724 static void subflow_ulp_fallback(struct sock *sk, 725 struct mptcp_subflow_context *old_ctx) 726 { 727 struct inet_connection_sock *icsk = inet_csk(sk); 728 729 mptcp_subflow_tcp_fallback(sk, old_ctx); 730 icsk->icsk_ulp_ops = NULL; 731 rcu_assign_pointer(icsk->icsk_ulp_data, NULL); 732 tcp_sk(sk)->is_mptcp = 0; 733 734 mptcp_subflow_ops_undo_override(sk); 735 } 736 737 void mptcp_subflow_drop_ctx(struct sock *ssk) 738 { 739 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 740 741 if (!ctx) 742 return; 743 744 list_del(&mptcp_subflow_ctx(ssk)->node); 745 if (inet_csk(ssk)->icsk_ulp_ops) { 746 subflow_ulp_fallback(ssk, ctx); 747 if (ctx->conn) 748 sock_put(ctx->conn); 749 } 750 751 kfree_rcu(ctx, rcu); 752 } 753 754 void __mptcp_subflow_fully_established(struct mptcp_sock *msk, 755 struct mptcp_subflow_context *subflow, 756 const struct mptcp_options_received *mp_opt) 757 { 758 subflow_set_remote_key(msk, subflow, mp_opt); 759 subflow->fully_established = 1; 760 WRITE_ONCE(msk->fully_established, true); 761 762 if (subflow->is_mptfo) 763 __mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt); 764 } 765 766 static struct sock *subflow_syn_recv_sock(const struct sock *sk, 767 struct sk_buff *skb, 768 struct request_sock *req, 769 struct dst_entry *dst, 770 struct request_sock *req_unhash, 771 bool *own_req) 772 { 773 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk); 774 struct mptcp_subflow_request_sock *subflow_req; 775 struct mptcp_options_received mp_opt; 776 bool fallback, fallback_is_fatal; 777 struct mptcp_sock *owner; 778 struct sock *child; 779 780 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn); 781 782 /* After child creation we must look for MPC even when options 783 * are not parsed 784 */ 785 mp_opt.suboptions = 0; 786 787 /* hopefully temporary handling for MP_JOIN+syncookie */ 788 subflow_req = mptcp_subflow_rsk(req); 789 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join; 790 fallback = !tcp_rsk(req)->is_mptcp; 791 if (fallback) 792 goto create_child; 793 794 /* if the sk is MP_CAPABLE, we try to fetch the client key */ 795 if (subflow_req->mp_capable) { 796 /* we can receive and accept an in-window, out-of-order pkt, 797 * which may not carry the MP_CAPABLE opt even on mptcp enabled 798 * paths: always try to extract the peer key, and fallback 799 * for packets missing it. 800 * Even OoO DSS packets coming legitly after dropped or 801 * reordered MPC will cause fallback, but we don't have other 802 * options. 803 */ 804 mptcp_get_options(skb, &mp_opt); 805 if (!(mp_opt.suboptions & 806 (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK))) 807 fallback = true; 808 809 } else if (subflow_req->mp_join) { 810 mptcp_get_options(skb, &mp_opt); 811 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) || 812 !subflow_hmac_valid(req, &mp_opt) || 813 !mptcp_can_accept_new_subflow(subflow_req->msk)) { 814 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC); 815 fallback = true; 816 } 817 } 818 819 create_child: 820 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, 821 req_unhash, own_req); 822 823 if (child && *own_req) { 824 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child); 825 826 tcp_rsk(req)->drop_req = false; 827 828 /* we need to fallback on ctx allocation failure and on pre-reqs 829 * checking above. In the latter scenario we additionally need 830 * to reset the context to non MPTCP status. 831 */ 832 if (!ctx || fallback) { 833 if (fallback_is_fatal) { 834 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); 835 goto dispose_child; 836 } 837 goto fallback; 838 } 839 840 /* ssk inherits options of listener sk */ 841 ctx->setsockopt_seq = listener->setsockopt_seq; 842 843 if (ctx->mp_capable) { 844 ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req); 845 if (!ctx->conn) 846 goto fallback; 847 848 ctx->subflow_id = 1; 849 owner = mptcp_sk(ctx->conn); 850 mptcp_pm_new_connection(owner, child, 1); 851 852 /* with OoO packets we can reach here without ingress 853 * mpc option 854 */ 855 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) { 856 mptcp_pm_fully_established(owner, child); 857 ctx->pm_notified = 1; 858 } 859 } else if (ctx->mp_join) { 860 owner = subflow_req->msk; 861 if (!owner) { 862 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); 863 goto dispose_child; 864 } 865 866 /* move the msk reference ownership to the subflow */ 867 subflow_req->msk = NULL; 868 ctx->conn = (struct sock *)owner; 869 870 if (subflow_use_different_sport(owner, sk)) { 871 pr_debug("ack inet_sport=%d %d", 872 ntohs(inet_sk(sk)->inet_sport), 873 ntohs(inet_sk((struct sock *)owner)->inet_sport)); 874 if (!mptcp_pm_sport_in_anno_list(owner, sk)) { 875 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX); 876 goto dispose_child; 877 } 878 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX); 879 } 880 881 if (!mptcp_finish_join(child)) 882 goto dispose_child; 883 884 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX); 885 tcp_rsk(req)->drop_req = true; 886 } 887 } 888 889 /* check for expected invariant - should never trigger, just help 890 * catching eariler subtle bugs 891 */ 892 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp && 893 (!mptcp_subflow_ctx(child) || 894 !mptcp_subflow_ctx(child)->conn)); 895 return child; 896 897 dispose_child: 898 mptcp_subflow_drop_ctx(child); 899 tcp_rsk(req)->drop_req = true; 900 inet_csk_prepare_for_destroy_sock(child); 901 tcp_done(child); 902 req->rsk_ops->send_reset(sk, skb); 903 904 /* The last child reference will be released by the caller */ 905 return child; 906 907 fallback: 908 mptcp_subflow_drop_ctx(child); 909 return child; 910 } 911 912 static struct inet_connection_sock_af_ops subflow_specific __ro_after_init; 913 static struct proto tcp_prot_override __ro_after_init; 914 915 enum mapping_status { 916 MAPPING_OK, 917 MAPPING_INVALID, 918 MAPPING_EMPTY, 919 MAPPING_DATA_FIN, 920 MAPPING_DUMMY, 921 MAPPING_BAD_CSUM 922 }; 923 924 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn) 925 { 926 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d", 927 ssn, subflow->map_subflow_seq, subflow->map_data_len); 928 } 929 930 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb) 931 { 932 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 933 unsigned int skb_consumed; 934 935 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq; 936 if (WARN_ON_ONCE(skb_consumed >= skb->len)) 937 return true; 938 939 return skb->len - skb_consumed <= subflow->map_data_len - 940 mptcp_subflow_get_map_offset(subflow); 941 } 942 943 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb) 944 { 945 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 946 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset; 947 948 if (unlikely(before(ssn, subflow->map_subflow_seq))) { 949 /* Mapping covers data later in the subflow stream, 950 * currently unsupported. 951 */ 952 dbg_bad_map(subflow, ssn); 953 return false; 954 } 955 if (unlikely(!before(ssn, subflow->map_subflow_seq + 956 subflow->map_data_len))) { 957 /* Mapping does covers past subflow data, invalid */ 958 dbg_bad_map(subflow, ssn); 959 return false; 960 } 961 return true; 962 } 963 964 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb, 965 bool csum_reqd) 966 { 967 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 968 u32 offset, seq, delta; 969 __sum16 csum; 970 int len; 971 972 if (!csum_reqd) 973 return MAPPING_OK; 974 975 /* mapping already validated on previous traversal */ 976 if (subflow->map_csum_len == subflow->map_data_len) 977 return MAPPING_OK; 978 979 /* traverse the receive queue, ensuring it contains a full 980 * DSS mapping and accumulating the related csum. 981 * Preserve the accoumlate csum across multiple calls, to compute 982 * the csum only once 983 */ 984 delta = subflow->map_data_len - subflow->map_csum_len; 985 for (;;) { 986 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len; 987 offset = seq - TCP_SKB_CB(skb)->seq; 988 989 /* if the current skb has not been accounted yet, csum its contents 990 * up to the amount covered by the current DSS 991 */ 992 if (offset < skb->len) { 993 __wsum csum; 994 995 len = min(skb->len - offset, delta); 996 csum = skb_checksum(skb, offset, len, 0); 997 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum, 998 subflow->map_csum_len); 999 1000 delta -= len; 1001 subflow->map_csum_len += len; 1002 } 1003 if (delta == 0) 1004 break; 1005 1006 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) { 1007 /* if this subflow is closed, the partial mapping 1008 * will be never completed; flush the pending skbs, so 1009 * that subflow_sched_work_if_closed() can kick in 1010 */ 1011 if (unlikely(ssk->sk_state == TCP_CLOSE)) 1012 while ((skb = skb_peek(&ssk->sk_receive_queue))) 1013 sk_eat_skb(ssk, skb); 1014 1015 /* not enough data to validate the csum */ 1016 return MAPPING_EMPTY; 1017 } 1018 1019 /* the DSS mapping for next skbs will be validated later, 1020 * when a get_mapping_status call will process such skb 1021 */ 1022 skb = skb->next; 1023 } 1024 1025 /* note that 'map_data_len' accounts only for the carried data, does 1026 * not include the eventual seq increment due to the data fin, 1027 * while the pseudo header requires the original DSS data len, 1028 * including that 1029 */ 1030 csum = __mptcp_make_csum(subflow->map_seq, 1031 subflow->map_subflow_seq, 1032 subflow->map_data_len + subflow->map_data_fin, 1033 subflow->map_data_csum); 1034 if (unlikely(csum)) { 1035 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR); 1036 return MAPPING_BAD_CSUM; 1037 } 1038 1039 subflow->valid_csum_seen = 1; 1040 return MAPPING_OK; 1041 } 1042 1043 static enum mapping_status get_mapping_status(struct sock *ssk, 1044 struct mptcp_sock *msk) 1045 { 1046 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1047 bool csum_reqd = READ_ONCE(msk->csum_enabled); 1048 struct mptcp_ext *mpext; 1049 struct sk_buff *skb; 1050 u16 data_len; 1051 u64 map_seq; 1052 1053 skb = skb_peek(&ssk->sk_receive_queue); 1054 if (!skb) 1055 return MAPPING_EMPTY; 1056 1057 if (mptcp_check_fallback(ssk)) 1058 return MAPPING_DUMMY; 1059 1060 mpext = mptcp_get_ext(skb); 1061 if (!mpext || !mpext->use_map) { 1062 if (!subflow->map_valid && !skb->len) { 1063 /* the TCP stack deliver 0 len FIN pkt to the receive 1064 * queue, that is the only 0len pkts ever expected here, 1065 * and we can admit no mapping only for 0 len pkts 1066 */ 1067 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1068 WARN_ONCE(1, "0len seq %d:%d flags %x", 1069 TCP_SKB_CB(skb)->seq, 1070 TCP_SKB_CB(skb)->end_seq, 1071 TCP_SKB_CB(skb)->tcp_flags); 1072 sk_eat_skb(ssk, skb); 1073 return MAPPING_EMPTY; 1074 } 1075 1076 if (!subflow->map_valid) 1077 return MAPPING_INVALID; 1078 1079 goto validate_seq; 1080 } 1081 1082 trace_get_mapping_status(mpext); 1083 1084 data_len = mpext->data_len; 1085 if (data_len == 0) { 1086 pr_debug("infinite mapping received"); 1087 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX); 1088 subflow->map_data_len = 0; 1089 return MAPPING_INVALID; 1090 } 1091 1092 if (mpext->data_fin == 1) { 1093 if (data_len == 1) { 1094 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq, 1095 mpext->dsn64); 1096 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq); 1097 if (subflow->map_valid) { 1098 /* A DATA_FIN might arrive in a DSS 1099 * option before the previous mapping 1100 * has been fully consumed. Continue 1101 * handling the existing mapping. 1102 */ 1103 skb_ext_del(skb, SKB_EXT_MPTCP); 1104 return MAPPING_OK; 1105 } else { 1106 if (updated) 1107 mptcp_schedule_work((struct sock *)msk); 1108 1109 return MAPPING_DATA_FIN; 1110 } 1111 } else { 1112 u64 data_fin_seq = mpext->data_seq + data_len - 1; 1113 1114 /* If mpext->data_seq is a 32-bit value, data_fin_seq 1115 * must also be limited to 32 bits. 1116 */ 1117 if (!mpext->dsn64) 1118 data_fin_seq &= GENMASK_ULL(31, 0); 1119 1120 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64); 1121 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d", 1122 data_fin_seq, mpext->dsn64); 1123 } 1124 1125 /* Adjust for DATA_FIN using 1 byte of sequence space */ 1126 data_len--; 1127 } 1128 1129 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64); 1130 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64); 1131 1132 if (subflow->map_valid) { 1133 /* Allow replacing only with an identical map */ 1134 if (subflow->map_seq == map_seq && 1135 subflow->map_subflow_seq == mpext->subflow_seq && 1136 subflow->map_data_len == data_len && 1137 subflow->map_csum_reqd == mpext->csum_reqd) { 1138 skb_ext_del(skb, SKB_EXT_MPTCP); 1139 goto validate_csum; 1140 } 1141 1142 /* If this skb data are fully covered by the current mapping, 1143 * the new map would need caching, which is not supported 1144 */ 1145 if (skb_is_fully_mapped(ssk, skb)) { 1146 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH); 1147 return MAPPING_INVALID; 1148 } 1149 1150 /* will validate the next map after consuming the current one */ 1151 goto validate_csum; 1152 } 1153 1154 subflow->map_seq = map_seq; 1155 subflow->map_subflow_seq = mpext->subflow_seq; 1156 subflow->map_data_len = data_len; 1157 subflow->map_valid = 1; 1158 subflow->map_data_fin = mpext->data_fin; 1159 subflow->mpc_map = mpext->mpc_map; 1160 subflow->map_csum_reqd = mpext->csum_reqd; 1161 subflow->map_csum_len = 0; 1162 subflow->map_data_csum = csum_unfold(mpext->csum); 1163 1164 /* Cfr RFC 8684 Section 3.3.0 */ 1165 if (unlikely(subflow->map_csum_reqd != csum_reqd)) 1166 return MAPPING_INVALID; 1167 1168 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u", 1169 subflow->map_seq, subflow->map_subflow_seq, 1170 subflow->map_data_len, subflow->map_csum_reqd, 1171 subflow->map_data_csum); 1172 1173 validate_seq: 1174 /* we revalidate valid mapping on new skb, because we must ensure 1175 * the current skb is completely covered by the available mapping 1176 */ 1177 if (!validate_mapping(ssk, skb)) { 1178 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH); 1179 return MAPPING_INVALID; 1180 } 1181 1182 skb_ext_del(skb, SKB_EXT_MPTCP); 1183 1184 validate_csum: 1185 return validate_data_csum(ssk, skb, csum_reqd); 1186 } 1187 1188 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb, 1189 u64 limit) 1190 { 1191 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1192 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN; 1193 u32 incr; 1194 1195 incr = limit >= skb->len ? skb->len + fin : limit; 1196 1197 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len, 1198 subflow->map_subflow_seq); 1199 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA); 1200 tcp_sk(ssk)->copied_seq += incr; 1201 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq)) 1202 sk_eat_skb(ssk, skb); 1203 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) 1204 subflow->map_valid = 0; 1205 } 1206 1207 /* sched mptcp worker to remove the subflow if no more data is pending */ 1208 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk) 1209 { 1210 if (likely(ssk->sk_state != TCP_CLOSE)) 1211 return; 1212 1213 if (skb_queue_empty(&ssk->sk_receive_queue) && 1214 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) 1215 mptcp_schedule_work((struct sock *)msk); 1216 } 1217 1218 static bool subflow_can_fallback(struct mptcp_subflow_context *subflow) 1219 { 1220 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 1221 1222 if (subflow->mp_join) 1223 return false; 1224 else if (READ_ONCE(msk->csum_enabled)) 1225 return !subflow->valid_csum_seen; 1226 else 1227 return !subflow->fully_established; 1228 } 1229 1230 static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk) 1231 { 1232 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1233 unsigned long fail_tout; 1234 1235 /* greceful failure can happen only on the MPC subflow */ 1236 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first))) 1237 return; 1238 1239 /* since the close timeout take precedence on the fail one, 1240 * no need to start the latter when the first is already set 1241 */ 1242 if (sock_flag((struct sock *)msk, SOCK_DEAD)) 1243 return; 1244 1245 /* we don't need extreme accuracy here, use a zero fail_tout as special 1246 * value meaning no fail timeout at all; 1247 */ 1248 fail_tout = jiffies + TCP_RTO_MAX; 1249 if (!fail_tout) 1250 fail_tout = 1; 1251 WRITE_ONCE(subflow->fail_tout, fail_tout); 1252 tcp_send_ack(ssk); 1253 1254 mptcp_reset_tout_timer(msk, subflow->fail_tout); 1255 } 1256 1257 static bool subflow_check_data_avail(struct sock *ssk) 1258 { 1259 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1260 enum mapping_status status; 1261 struct mptcp_sock *msk; 1262 struct sk_buff *skb; 1263 1264 if (!skb_peek(&ssk->sk_receive_queue)) 1265 WRITE_ONCE(subflow->data_avail, false); 1266 if (subflow->data_avail) 1267 return true; 1268 1269 msk = mptcp_sk(subflow->conn); 1270 for (;;) { 1271 u64 ack_seq; 1272 u64 old_ack; 1273 1274 status = get_mapping_status(ssk, msk); 1275 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue)); 1276 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY || 1277 status == MAPPING_BAD_CSUM)) 1278 goto fallback; 1279 1280 if (status != MAPPING_OK) 1281 goto no_data; 1282 1283 skb = skb_peek(&ssk->sk_receive_queue); 1284 if (WARN_ON_ONCE(!skb)) 1285 goto no_data; 1286 1287 if (unlikely(!READ_ONCE(msk->can_ack))) 1288 goto fallback; 1289 1290 old_ack = READ_ONCE(msk->ack_seq); 1291 ack_seq = mptcp_subflow_get_mapped_dsn(subflow); 1292 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack, 1293 ack_seq); 1294 if (unlikely(before64(ack_seq, old_ack))) { 1295 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq); 1296 continue; 1297 } 1298 1299 WRITE_ONCE(subflow->data_avail, true); 1300 break; 1301 } 1302 return true; 1303 1304 no_data: 1305 subflow_sched_work_if_closed(msk, ssk); 1306 return false; 1307 1308 fallback: 1309 if (!__mptcp_check_fallback(msk)) { 1310 /* RFC 8684 section 3.7. */ 1311 if (status == MAPPING_BAD_CSUM && 1312 (subflow->mp_join || subflow->valid_csum_seen)) { 1313 subflow->send_mp_fail = 1; 1314 1315 if (!READ_ONCE(msk->allow_infinite_fallback)) { 1316 subflow->reset_transient = 0; 1317 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX; 1318 goto reset; 1319 } 1320 mptcp_subflow_fail(msk, ssk); 1321 WRITE_ONCE(subflow->data_avail, true); 1322 return true; 1323 } 1324 1325 if (!subflow_can_fallback(subflow) && subflow->map_data_len) { 1326 /* fatal protocol error, close the socket. 1327 * subflow_error_report() will introduce the appropriate barriers 1328 */ 1329 subflow->reset_transient = 0; 1330 subflow->reset_reason = MPTCP_RST_EMPTCP; 1331 1332 reset: 1333 WRITE_ONCE(ssk->sk_err, EBADMSG); 1334 tcp_set_state(ssk, TCP_CLOSE); 1335 while ((skb = skb_peek(&ssk->sk_receive_queue))) 1336 sk_eat_skb(ssk, skb); 1337 tcp_send_active_reset(ssk, GFP_ATOMIC); 1338 WRITE_ONCE(subflow->data_avail, false); 1339 return false; 1340 } 1341 1342 mptcp_do_fallback(ssk); 1343 } 1344 1345 skb = skb_peek(&ssk->sk_receive_queue); 1346 subflow->map_valid = 1; 1347 subflow->map_seq = READ_ONCE(msk->ack_seq); 1348 subflow->map_data_len = skb->len; 1349 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset; 1350 WRITE_ONCE(subflow->data_avail, true); 1351 return true; 1352 } 1353 1354 bool mptcp_subflow_data_available(struct sock *sk) 1355 { 1356 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1357 1358 /* check if current mapping is still valid */ 1359 if (subflow->map_valid && 1360 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) { 1361 subflow->map_valid = 0; 1362 WRITE_ONCE(subflow->data_avail, false); 1363 1364 pr_debug("Done with mapping: seq=%u data_len=%u", 1365 subflow->map_subflow_seq, 1366 subflow->map_data_len); 1367 } 1368 1369 return subflow_check_data_avail(sk); 1370 } 1371 1372 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy, 1373 * not the ssk one. 1374 * 1375 * In mptcp, rwin is about the mptcp-level connection data. 1376 * 1377 * Data that is still on the ssk rx queue can thus be ignored, 1378 * as far as mptcp peer is concerned that data is still inflight. 1379 * DSS ACK is updated when skb is moved to the mptcp rx queue. 1380 */ 1381 void mptcp_space(const struct sock *ssk, int *space, int *full_space) 1382 { 1383 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1384 const struct sock *sk = subflow->conn; 1385 1386 *space = __mptcp_space(sk); 1387 *full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf)); 1388 } 1389 1390 static void subflow_error_report(struct sock *ssk) 1391 { 1392 struct sock *sk = mptcp_subflow_ctx(ssk)->conn; 1393 1394 /* bail early if this is a no-op, so that we avoid introducing a 1395 * problematic lockdep dependency between TCP accept queue lock 1396 * and msk socket spinlock 1397 */ 1398 if (!sk->sk_socket) 1399 return; 1400 1401 mptcp_data_lock(sk); 1402 if (!sock_owned_by_user(sk)) 1403 __mptcp_error_report(sk); 1404 else 1405 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags); 1406 mptcp_data_unlock(sk); 1407 } 1408 1409 static void subflow_data_ready(struct sock *sk) 1410 { 1411 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1412 u16 state = 1 << inet_sk_state_load(sk); 1413 struct sock *parent = subflow->conn; 1414 struct mptcp_sock *msk; 1415 1416 trace_sk_data_ready(sk); 1417 1418 msk = mptcp_sk(parent); 1419 if (state & TCPF_LISTEN) { 1420 /* MPJ subflow are removed from accept queue before reaching here, 1421 * avoid stray wakeups 1422 */ 1423 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue)) 1424 return; 1425 1426 parent->sk_data_ready(parent); 1427 return; 1428 } 1429 1430 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && 1431 !subflow->mp_join && !(state & TCPF_CLOSE)); 1432 1433 if (mptcp_subflow_data_available(sk)) { 1434 mptcp_data_ready(parent, sk); 1435 1436 /* subflow-level lowat test are not relevant. 1437 * respect the msk-level threshold eventually mandating an immediate ack 1438 */ 1439 if (mptcp_data_avail(msk) < parent->sk_rcvlowat && 1440 (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss) 1441 inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW; 1442 } else if (unlikely(sk->sk_err)) { 1443 subflow_error_report(sk); 1444 } 1445 } 1446 1447 static void subflow_write_space(struct sock *ssk) 1448 { 1449 struct sock *sk = mptcp_subflow_ctx(ssk)->conn; 1450 1451 mptcp_propagate_sndbuf(sk, ssk); 1452 mptcp_write_space(sk); 1453 } 1454 1455 static const struct inet_connection_sock_af_ops * 1456 subflow_default_af_ops(struct sock *sk) 1457 { 1458 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1459 if (sk->sk_family == AF_INET6) 1460 return &subflow_v6_specific; 1461 #endif 1462 return &subflow_specific; 1463 } 1464 1465 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1466 void mptcpv6_handle_mapped(struct sock *sk, bool mapped) 1467 { 1468 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1469 struct inet_connection_sock *icsk = inet_csk(sk); 1470 const struct inet_connection_sock_af_ops *target; 1471 1472 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk); 1473 1474 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d", 1475 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped); 1476 1477 if (likely(icsk->icsk_af_ops == target)) 1478 return; 1479 1480 subflow->icsk_af_ops = icsk->icsk_af_ops; 1481 icsk->icsk_af_ops = target; 1482 } 1483 #endif 1484 1485 void mptcp_info2sockaddr(const struct mptcp_addr_info *info, 1486 struct sockaddr_storage *addr, 1487 unsigned short family) 1488 { 1489 memset(addr, 0, sizeof(*addr)); 1490 addr->ss_family = family; 1491 if (addr->ss_family == AF_INET) { 1492 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr; 1493 1494 if (info->family == AF_INET) 1495 in_addr->sin_addr = info->addr; 1496 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1497 else if (ipv6_addr_v4mapped(&info->addr6)) 1498 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3]; 1499 #endif 1500 in_addr->sin_port = info->port; 1501 } 1502 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1503 else if (addr->ss_family == AF_INET6) { 1504 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr; 1505 1506 if (info->family == AF_INET) 1507 ipv6_addr_set_v4mapped(info->addr.s_addr, 1508 &in6_addr->sin6_addr); 1509 else 1510 in6_addr->sin6_addr = info->addr6; 1511 in6_addr->sin6_port = info->port; 1512 } 1513 #endif 1514 } 1515 1516 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc, 1517 const struct mptcp_addr_info *remote) 1518 { 1519 struct mptcp_sock *msk = mptcp_sk(sk); 1520 struct mptcp_subflow_context *subflow; 1521 struct sockaddr_storage addr; 1522 int remote_id = remote->id; 1523 int local_id = loc->id; 1524 int err = -ENOTCONN; 1525 struct socket *sf; 1526 struct sock *ssk; 1527 u32 remote_token; 1528 int addrlen; 1529 int ifindex; 1530 u8 flags; 1531 1532 if (!mptcp_is_fully_established(sk)) 1533 goto err_out; 1534 1535 err = mptcp_subflow_create_socket(sk, loc->family, &sf); 1536 if (err) 1537 goto err_out; 1538 1539 ssk = sf->sk; 1540 subflow = mptcp_subflow_ctx(ssk); 1541 do { 1542 get_random_bytes(&subflow->local_nonce, sizeof(u32)); 1543 } while (!subflow->local_nonce); 1544 1545 if (local_id) 1546 subflow_set_local_id(subflow, local_id); 1547 1548 mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id, 1549 &flags, &ifindex); 1550 subflow->remote_key_valid = 1; 1551 subflow->remote_key = READ_ONCE(msk->remote_key); 1552 subflow->local_key = READ_ONCE(msk->local_key); 1553 subflow->token = msk->token; 1554 mptcp_info2sockaddr(loc, &addr, ssk->sk_family); 1555 1556 addrlen = sizeof(struct sockaddr_in); 1557 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1558 if (addr.ss_family == AF_INET6) 1559 addrlen = sizeof(struct sockaddr_in6); 1560 #endif 1561 ssk->sk_bound_dev_if = ifindex; 1562 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen); 1563 if (err) 1564 goto failed; 1565 1566 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL); 1567 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk, 1568 remote_token, local_id, remote_id); 1569 subflow->remote_token = remote_token; 1570 WRITE_ONCE(subflow->remote_id, remote_id); 1571 subflow->request_join = 1; 1572 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP); 1573 subflow->subflow_id = msk->subflow_id++; 1574 mptcp_info2sockaddr(remote, &addr, ssk->sk_family); 1575 1576 sock_hold(ssk); 1577 list_add_tail(&subflow->node, &msk->conn_list); 1578 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK); 1579 if (err && err != -EINPROGRESS) 1580 goto failed_unlink; 1581 1582 /* discard the subflow socket */ 1583 mptcp_sock_graft(ssk, sk->sk_socket); 1584 iput(SOCK_INODE(sf)); 1585 WRITE_ONCE(msk->allow_infinite_fallback, false); 1586 mptcp_stop_tout_timer(sk); 1587 return 0; 1588 1589 failed_unlink: 1590 list_del(&subflow->node); 1591 sock_put(mptcp_subflow_tcp_sock(subflow)); 1592 1593 failed: 1594 subflow->disposable = 1; 1595 sock_release(sf); 1596 1597 err_out: 1598 /* we account subflows before the creation, and this failures will not 1599 * be caught by sk_state_change() 1600 */ 1601 mptcp_pm_close_subflow(msk); 1602 return err; 1603 } 1604 1605 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child) 1606 { 1607 #ifdef CONFIG_SOCK_CGROUP_DATA 1608 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data, 1609 *child_skcd = &child->sk_cgrp_data; 1610 1611 /* only the additional subflows created by kworkers have to be modified */ 1612 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) != 1613 cgroup_id(sock_cgroup_ptr(child_skcd))) { 1614 #ifdef CONFIG_MEMCG 1615 struct mem_cgroup *memcg = parent->sk_memcg; 1616 1617 mem_cgroup_sk_free(child); 1618 if (memcg && css_tryget(&memcg->css)) 1619 child->sk_memcg = memcg; 1620 #endif /* CONFIG_MEMCG */ 1621 1622 cgroup_sk_free(child_skcd); 1623 *child_skcd = *parent_skcd; 1624 cgroup_sk_clone(child_skcd); 1625 } 1626 #endif /* CONFIG_SOCK_CGROUP_DATA */ 1627 } 1628 1629 static void mptcp_subflow_ops_override(struct sock *ssk) 1630 { 1631 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1632 if (ssk->sk_prot == &tcpv6_prot) 1633 ssk->sk_prot = &tcpv6_prot_override; 1634 else 1635 #endif 1636 ssk->sk_prot = &tcp_prot_override; 1637 } 1638 1639 static void mptcp_subflow_ops_undo_override(struct sock *ssk) 1640 { 1641 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1642 if (ssk->sk_prot == &tcpv6_prot_override) 1643 ssk->sk_prot = &tcpv6_prot; 1644 else 1645 #endif 1646 ssk->sk_prot = &tcp_prot; 1647 } 1648 1649 int mptcp_subflow_create_socket(struct sock *sk, unsigned short family, 1650 struct socket **new_sock) 1651 { 1652 struct mptcp_subflow_context *subflow; 1653 struct net *net = sock_net(sk); 1654 struct socket *sf; 1655 int err; 1656 1657 /* un-accepted server sockets can reach here - on bad configuration 1658 * bail early to avoid greater trouble later 1659 */ 1660 if (unlikely(!sk->sk_socket)) 1661 return -EINVAL; 1662 1663 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf); 1664 if (err) 1665 return err; 1666 1667 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING); 1668 1669 err = security_mptcp_add_subflow(sk, sf->sk); 1670 if (err) 1671 goto err_free; 1672 1673 /* the newly created socket has to be in the same cgroup as its parent */ 1674 mptcp_attach_cgroup(sk, sf->sk); 1675 1676 /* kernel sockets do not by default acquire net ref, but TCP timer 1677 * needs it. 1678 * Update ns_tracker to current stack trace and refcounted tracker. 1679 */ 1680 __netns_tracker_free(net, &sf->sk->ns_tracker, false); 1681 sf->sk->sk_net_refcnt = 1; 1682 get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL); 1683 sock_inuse_add(net, 1); 1684 err = tcp_set_ulp(sf->sk, "mptcp"); 1685 if (err) 1686 goto err_free; 1687 1688 mptcp_sockopt_sync_locked(mptcp_sk(sk), sf->sk); 1689 release_sock(sf->sk); 1690 1691 /* the newly created socket really belongs to the owning MPTCP master 1692 * socket, even if for additional subflows the allocation is performed 1693 * by a kernel workqueue. Adjust inode references, so that the 1694 * procfs/diag interfaces really show this one belonging to the correct 1695 * user. 1696 */ 1697 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino; 1698 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid; 1699 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid; 1700 1701 subflow = mptcp_subflow_ctx(sf->sk); 1702 pr_debug("subflow=%p", subflow); 1703 1704 *new_sock = sf; 1705 sock_hold(sk); 1706 subflow->conn = sk; 1707 mptcp_subflow_ops_override(sf->sk); 1708 1709 return 0; 1710 1711 err_free: 1712 release_sock(sf->sk); 1713 sock_release(sf); 1714 return err; 1715 } 1716 1717 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk, 1718 gfp_t priority) 1719 { 1720 struct inet_connection_sock *icsk = inet_csk(sk); 1721 struct mptcp_subflow_context *ctx; 1722 1723 ctx = kzalloc(sizeof(*ctx), priority); 1724 if (!ctx) 1725 return NULL; 1726 1727 rcu_assign_pointer(icsk->icsk_ulp_data, ctx); 1728 INIT_LIST_HEAD(&ctx->node); 1729 INIT_LIST_HEAD(&ctx->delegated_node); 1730 1731 pr_debug("subflow=%p", ctx); 1732 1733 ctx->tcp_sock = sk; 1734 WRITE_ONCE(ctx->local_id, -1); 1735 1736 return ctx; 1737 } 1738 1739 static void __subflow_state_change(struct sock *sk) 1740 { 1741 struct socket_wq *wq; 1742 1743 rcu_read_lock(); 1744 wq = rcu_dereference(sk->sk_wq); 1745 if (skwq_has_sleeper(wq)) 1746 wake_up_interruptible_all(&wq->wait); 1747 rcu_read_unlock(); 1748 } 1749 1750 static bool subflow_is_done(const struct sock *sk) 1751 { 1752 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE; 1753 } 1754 1755 static void subflow_state_change(struct sock *sk) 1756 { 1757 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1758 struct sock *parent = subflow->conn; 1759 struct mptcp_sock *msk; 1760 1761 __subflow_state_change(sk); 1762 1763 msk = mptcp_sk(parent); 1764 if (subflow_simultaneous_connect(sk)) { 1765 mptcp_do_fallback(sk); 1766 pr_fallback(msk); 1767 subflow->conn_finished = 1; 1768 mptcp_propagate_state(parent, sk, subflow, NULL); 1769 } 1770 1771 /* as recvmsg() does not acquire the subflow socket for ssk selection 1772 * a fin packet carrying a DSS can be unnoticed if we don't trigger 1773 * the data available machinery here. 1774 */ 1775 if (mptcp_subflow_data_available(sk)) 1776 mptcp_data_ready(parent, sk); 1777 else if (unlikely(sk->sk_err)) 1778 subflow_error_report(sk); 1779 1780 subflow_sched_work_if_closed(mptcp_sk(parent), sk); 1781 1782 /* when the fallback subflow closes the rx side, trigger a 'dummy' 1783 * ingress data fin, so that the msk state will follow along 1784 */ 1785 if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk && 1786 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true)) 1787 mptcp_schedule_work(parent); 1788 } 1789 1790 void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk) 1791 { 1792 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue; 1793 struct request_sock *req, *head, *tail; 1794 struct mptcp_subflow_context *subflow; 1795 struct sock *sk, *ssk; 1796 1797 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock. 1798 * Splice the req list, so that accept() can not reach the pending ssk after 1799 * the listener socket is released below. 1800 */ 1801 spin_lock_bh(&queue->rskq_lock); 1802 head = queue->rskq_accept_head; 1803 tail = queue->rskq_accept_tail; 1804 queue->rskq_accept_head = NULL; 1805 queue->rskq_accept_tail = NULL; 1806 spin_unlock_bh(&queue->rskq_lock); 1807 1808 if (!head) 1809 return; 1810 1811 /* can't acquire the msk socket lock under the subflow one, 1812 * or will cause ABBA deadlock 1813 */ 1814 release_sock(listener_ssk); 1815 1816 for (req = head; req; req = req->dl_next) { 1817 ssk = req->sk; 1818 if (!sk_is_mptcp(ssk)) 1819 continue; 1820 1821 subflow = mptcp_subflow_ctx(ssk); 1822 if (!subflow || !subflow->conn) 1823 continue; 1824 1825 sk = subflow->conn; 1826 sock_hold(sk); 1827 1828 lock_sock_nested(sk, SINGLE_DEPTH_NESTING); 1829 __mptcp_unaccepted_force_close(sk); 1830 release_sock(sk); 1831 1832 /* lockdep will report a false positive ABBA deadlock 1833 * between cancel_work_sync and the listener socket. 1834 * The involved locks belong to different sockets WRT 1835 * the existing AB chain. 1836 * Using a per socket key is problematic as key 1837 * deregistration requires process context and must be 1838 * performed at socket disposal time, in atomic 1839 * context. 1840 * Just tell lockdep to consider the listener socket 1841 * released here. 1842 */ 1843 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_); 1844 mptcp_cancel_work(sk); 1845 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_); 1846 1847 sock_put(sk); 1848 } 1849 1850 /* we are still under the listener msk socket lock */ 1851 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING); 1852 1853 /* restore the listener queue, to let the TCP code clean it up */ 1854 spin_lock_bh(&queue->rskq_lock); 1855 WARN_ON_ONCE(queue->rskq_accept_head); 1856 queue->rskq_accept_head = head; 1857 queue->rskq_accept_tail = tail; 1858 spin_unlock_bh(&queue->rskq_lock); 1859 } 1860 1861 static int subflow_ulp_init(struct sock *sk) 1862 { 1863 struct inet_connection_sock *icsk = inet_csk(sk); 1864 struct mptcp_subflow_context *ctx; 1865 struct tcp_sock *tp = tcp_sk(sk); 1866 int err = 0; 1867 1868 /* disallow attaching ULP to a socket unless it has been 1869 * created with sock_create_kern() 1870 */ 1871 if (!sk->sk_kern_sock) { 1872 err = -EOPNOTSUPP; 1873 goto out; 1874 } 1875 1876 ctx = subflow_create_ctx(sk, GFP_KERNEL); 1877 if (!ctx) { 1878 err = -ENOMEM; 1879 goto out; 1880 } 1881 1882 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family); 1883 1884 tp->is_mptcp = 1; 1885 ctx->icsk_af_ops = icsk->icsk_af_ops; 1886 icsk->icsk_af_ops = subflow_default_af_ops(sk); 1887 ctx->tcp_state_change = sk->sk_state_change; 1888 ctx->tcp_error_report = sk->sk_error_report; 1889 1890 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable); 1891 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space); 1892 1893 sk->sk_data_ready = subflow_data_ready; 1894 sk->sk_write_space = subflow_write_space; 1895 sk->sk_state_change = subflow_state_change; 1896 sk->sk_error_report = subflow_error_report; 1897 out: 1898 return err; 1899 } 1900 1901 static void subflow_ulp_release(struct sock *ssk) 1902 { 1903 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 1904 bool release = true; 1905 struct sock *sk; 1906 1907 if (!ctx) 1908 return; 1909 1910 sk = ctx->conn; 1911 if (sk) { 1912 /* if the msk has been orphaned, keep the ctx 1913 * alive, will be freed by __mptcp_close_ssk(), 1914 * when the subflow is still unaccepted 1915 */ 1916 release = ctx->disposable || list_empty(&ctx->node); 1917 1918 /* inet_child_forget() does not call sk_state_change(), 1919 * explicitly trigger the socket close machinery 1920 */ 1921 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, 1922 &mptcp_sk(sk)->flags)) 1923 mptcp_schedule_work(sk); 1924 sock_put(sk); 1925 } 1926 1927 mptcp_subflow_ops_undo_override(ssk); 1928 if (release) 1929 kfree_rcu(ctx, rcu); 1930 } 1931 1932 static void subflow_ulp_clone(const struct request_sock *req, 1933 struct sock *newsk, 1934 const gfp_t priority) 1935 { 1936 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 1937 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk); 1938 struct mptcp_subflow_context *new_ctx; 1939 1940 if (!tcp_rsk(req)->is_mptcp || 1941 (!subflow_req->mp_capable && !subflow_req->mp_join)) { 1942 subflow_ulp_fallback(newsk, old_ctx); 1943 return; 1944 } 1945 1946 new_ctx = subflow_create_ctx(newsk, priority); 1947 if (!new_ctx) { 1948 subflow_ulp_fallback(newsk, old_ctx); 1949 return; 1950 } 1951 1952 new_ctx->conn_finished = 1; 1953 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops; 1954 new_ctx->tcp_state_change = old_ctx->tcp_state_change; 1955 new_ctx->tcp_error_report = old_ctx->tcp_error_report; 1956 new_ctx->rel_write_seq = 1; 1957 new_ctx->tcp_sock = newsk; 1958 1959 if (subflow_req->mp_capable) { 1960 /* see comments in subflow_syn_recv_sock(), MPTCP connection 1961 * is fully established only after we receive the remote key 1962 */ 1963 new_ctx->mp_capable = 1; 1964 new_ctx->local_key = subflow_req->local_key; 1965 new_ctx->token = subflow_req->token; 1966 new_ctx->ssn_offset = subflow_req->ssn_offset; 1967 new_ctx->idsn = subflow_req->idsn; 1968 1969 /* this is the first subflow, id is always 0 */ 1970 subflow_set_local_id(new_ctx, 0); 1971 } else if (subflow_req->mp_join) { 1972 new_ctx->ssn_offset = subflow_req->ssn_offset; 1973 new_ctx->mp_join = 1; 1974 new_ctx->fully_established = 1; 1975 new_ctx->remote_key_valid = 1; 1976 new_ctx->backup = subflow_req->backup; 1977 WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id); 1978 new_ctx->token = subflow_req->token; 1979 new_ctx->thmac = subflow_req->thmac; 1980 1981 /* the subflow req id is valid, fetched via subflow_check_req() 1982 * and subflow_token_join_request() 1983 */ 1984 subflow_set_local_id(new_ctx, subflow_req->local_id); 1985 } 1986 } 1987 1988 static void tcp_release_cb_override(struct sock *ssk) 1989 { 1990 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1991 long status; 1992 1993 /* process and clear all the pending actions, but leave the subflow into 1994 * the napi queue. To respect locking, only the same CPU that originated 1995 * the action can touch the list. mptcp_napi_poll will take care of it. 1996 */ 1997 status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0); 1998 if (status) 1999 mptcp_subflow_process_delegated(ssk, status); 2000 2001 tcp_release_cb(ssk); 2002 } 2003 2004 static int tcp_abort_override(struct sock *ssk, int err) 2005 { 2006 /* closing a listener subflow requires a great deal of care. 2007 * keep it simple and just prevent such operation 2008 */ 2009 if (inet_sk_state_load(ssk) == TCP_LISTEN) 2010 return -EINVAL; 2011 2012 return tcp_abort(ssk, err); 2013 } 2014 2015 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = { 2016 .name = "mptcp", 2017 .owner = THIS_MODULE, 2018 .init = subflow_ulp_init, 2019 .release = subflow_ulp_release, 2020 .clone = subflow_ulp_clone, 2021 }; 2022 2023 static int subflow_ops_init(struct request_sock_ops *subflow_ops) 2024 { 2025 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock); 2026 2027 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name, 2028 subflow_ops->obj_size, 0, 2029 SLAB_ACCOUNT | 2030 SLAB_TYPESAFE_BY_RCU, 2031 NULL); 2032 if (!subflow_ops->slab) 2033 return -ENOMEM; 2034 2035 return 0; 2036 } 2037 2038 void __init mptcp_subflow_init(void) 2039 { 2040 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops; 2041 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4"; 2042 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor; 2043 2044 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0) 2045 panic("MPTCP: failed to init subflow v4 request sock ops\n"); 2046 2047 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops; 2048 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req; 2049 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack; 2050 2051 subflow_specific = ipv4_specific; 2052 subflow_specific.conn_request = subflow_v4_conn_request; 2053 subflow_specific.syn_recv_sock = subflow_syn_recv_sock; 2054 subflow_specific.sk_rx_dst_set = subflow_finish_connect; 2055 subflow_specific.rebuild_header = subflow_rebuild_header; 2056 2057 tcp_prot_override = tcp_prot; 2058 tcp_prot_override.release_cb = tcp_release_cb_override; 2059 tcp_prot_override.diag_destroy = tcp_abort_override; 2060 2061 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 2062 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock 2063 * structures for v4 and v6 have the same size. It should not changed in 2064 * the future but better to make sure to be warned if it is no longer 2065 * the case. 2066 */ 2067 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock)); 2068 2069 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops; 2070 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6"; 2071 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor; 2072 2073 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0) 2074 panic("MPTCP: failed to init subflow v6 request sock ops\n"); 2075 2076 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops; 2077 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req; 2078 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack; 2079 2080 subflow_v6_specific = ipv6_specific; 2081 subflow_v6_specific.conn_request = subflow_v6_conn_request; 2082 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock; 2083 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect; 2084 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header; 2085 2086 subflow_v6m_specific = subflow_v6_specific; 2087 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit; 2088 subflow_v6m_specific.send_check = ipv4_specific.send_check; 2089 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len; 2090 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced; 2091 subflow_v6m_specific.rebuild_header = subflow_rebuild_header; 2092 2093 tcpv6_prot_override = tcpv6_prot; 2094 tcpv6_prot_override.release_cb = tcp_release_cb_override; 2095 tcpv6_prot_override.diag_destroy = tcp_abort_override; 2096 #endif 2097 2098 mptcp_diag_subflow_init(&subflow_ulp_ops); 2099 2100 if (tcp_register_ulp(&subflow_ulp_ops) != 0) 2101 panic("MPTCP: failed to register subflows to ULP\n"); 2102 } 2103