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 24 #include "protocol.h" 25 #include "mib.h" 26 27 #include <trace/events/mptcp.h> 28 #include <trace/events/sock.h> 29 30 static void mptcp_subflow_ops_undo_override(struct sock *ssk); 31 32 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req, 33 enum linux_mptcp_mib_field field) 34 { 35 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field); 36 } 37 38 static void subflow_req_destructor(struct request_sock *req) 39 { 40 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 41 42 pr_debug("subflow_req=%p\n", subflow_req); 43 44 if (subflow_req->msk) 45 sock_put((struct sock *)subflow_req->msk); 46 47 mptcp_token_destroy_request(req); 48 } 49 50 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2, 51 void *hmac) 52 { 53 u8 msg[8]; 54 55 put_unaligned_be32(nonce1, &msg[0]); 56 put_unaligned_be32(nonce2, &msg[4]); 57 58 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac); 59 } 60 61 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk) 62 { 63 return mptcp_is_fully_established((void *)msk) && 64 ((mptcp_pm_is_userspace(msk) && 65 mptcp_userspace_pm_active(msk)) || 66 READ_ONCE(msk->pm.accept_subflow)); 67 } 68 69 /* validate received token and create truncated hmac and nonce for SYN-ACK */ 70 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req) 71 { 72 struct mptcp_sock *msk = subflow_req->msk; 73 u8 hmac[SHA256_DIGEST_SIZE]; 74 75 get_random_bytes(&subflow_req->local_nonce, sizeof(u32)); 76 77 subflow_generate_hmac(READ_ONCE(msk->local_key), 78 READ_ONCE(msk->remote_key), 79 subflow_req->local_nonce, 80 subflow_req->remote_nonce, hmac); 81 82 subflow_req->thmac = get_unaligned_be64(hmac); 83 } 84 85 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req) 86 { 87 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 88 struct mptcp_sock *msk; 89 int local_id; 90 91 msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token); 92 if (!msk) { 93 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN); 94 return NULL; 95 } 96 97 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req); 98 if (local_id < 0) { 99 sock_put((struct sock *)msk); 100 return NULL; 101 } 102 subflow_req->local_id = local_id; 103 subflow_req->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)req); 104 105 return msk; 106 } 107 108 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener) 109 { 110 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 111 112 subflow_req->mp_capable = 0; 113 subflow_req->mp_join = 0; 114 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener)); 115 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener)); 116 subflow_req->msk = NULL; 117 mptcp_token_init_request(req); 118 } 119 120 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk) 121 { 122 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport; 123 } 124 125 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason) 126 { 127 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 128 129 if (mpext) { 130 memset(mpext, 0, sizeof(*mpext)); 131 mpext->reset_reason = reason; 132 } 133 } 134 135 static int subflow_reset_req_endp(struct request_sock *req, struct sk_buff *skb) 136 { 137 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEENDPATTEMPT); 138 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); 139 return -EPERM; 140 } 141 142 /* Init mptcp request socket. 143 * 144 * Returns an error code if a JOIN has failed and a TCP reset 145 * should be sent. 146 */ 147 static int subflow_check_req(struct request_sock *req, 148 const struct sock *sk_listener, 149 struct sk_buff *skb) 150 { 151 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 152 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 153 struct mptcp_options_received mp_opt; 154 bool opt_mp_capable, opt_mp_join; 155 156 pr_debug("subflow_req=%p, listener=%p\n", subflow_req, listener); 157 158 #ifdef CONFIG_TCP_MD5SIG 159 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of 160 * TCP option space. 161 */ 162 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) { 163 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); 164 return -EINVAL; 165 } 166 #endif 167 168 mptcp_get_options(skb, &mp_opt); 169 170 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN); 171 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN); 172 if (opt_mp_capable) { 173 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE); 174 175 if (unlikely(listener->pm_listener)) 176 return subflow_reset_req_endp(req, skb); 177 if (opt_mp_join) 178 return 0; 179 } else if (opt_mp_join) { 180 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX); 181 182 if (mp_opt.backup) 183 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNBACKUPRX); 184 } else if (unlikely(listener->pm_listener)) { 185 return subflow_reset_req_endp(req, skb); 186 } 187 188 if (opt_mp_capable && listener->request_mptcp) { 189 int err, retries = MPTCP_TOKEN_MAX_RETRIES; 190 191 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 192 again: 193 do { 194 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key)); 195 } while (subflow_req->local_key == 0); 196 197 if (unlikely(req->syncookie)) { 198 mptcp_crypto_key_sha(subflow_req->local_key, 199 &subflow_req->token, 200 &subflow_req->idsn); 201 if (mptcp_token_exists(subflow_req->token)) { 202 if (retries-- > 0) 203 goto again; 204 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT); 205 } else { 206 subflow_req->mp_capable = 1; 207 } 208 return 0; 209 } 210 211 err = mptcp_token_new_request(req); 212 if (err == 0) 213 subflow_req->mp_capable = 1; 214 else if (retries-- > 0) 215 goto again; 216 else 217 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT); 218 219 } else if (opt_mp_join && listener->request_mptcp) { 220 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 221 subflow_req->mp_join = 1; 222 subflow_req->backup = mp_opt.backup; 223 subflow_req->remote_id = mp_opt.join_id; 224 subflow_req->token = mp_opt.token; 225 subflow_req->remote_nonce = mp_opt.nonce; 226 subflow_req->msk = subflow_token_join_request(req); 227 228 /* Can't fall back to TCP in this case. */ 229 if (!subflow_req->msk) { 230 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); 231 return -EPERM; 232 } 233 234 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) { 235 pr_debug("syn inet_sport=%d %d\n", 236 ntohs(inet_sk(sk_listener)->inet_sport), 237 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport)); 238 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) { 239 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX); 240 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); 241 return -EPERM; 242 } 243 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX); 244 } 245 246 subflow_req_create_thmac(subflow_req); 247 248 if (unlikely(req->syncookie)) { 249 if (!mptcp_can_accept_new_subflow(subflow_req->msk)) { 250 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); 251 return -EPERM; 252 } 253 254 subflow_init_req_cookie_join_save(subflow_req, skb); 255 } 256 257 pr_debug("token=%u, remote_nonce=%u msk=%p\n", subflow_req->token, 258 subflow_req->remote_nonce, subflow_req->msk); 259 } 260 261 return 0; 262 } 263 264 int mptcp_subflow_init_cookie_req(struct request_sock *req, 265 const struct sock *sk_listener, 266 struct sk_buff *skb) 267 { 268 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 269 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 270 struct mptcp_options_received mp_opt; 271 bool opt_mp_capable, opt_mp_join; 272 int err; 273 274 subflow_init_req(req, sk_listener); 275 mptcp_get_options(skb, &mp_opt); 276 277 opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK); 278 opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK); 279 if (opt_mp_capable && opt_mp_join) 280 return -EINVAL; 281 282 if (opt_mp_capable && listener->request_mptcp) { 283 if (mp_opt.sndr_key == 0) 284 return -EINVAL; 285 286 subflow_req->local_key = mp_opt.rcvr_key; 287 err = mptcp_token_new_request(req); 288 if (err) 289 return err; 290 291 subflow_req->mp_capable = 1; 292 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 293 } else if (opt_mp_join && listener->request_mptcp) { 294 if (!mptcp_token_join_cookie_init_state(subflow_req, skb)) 295 return -EINVAL; 296 297 subflow_req->mp_join = 1; 298 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 299 } 300 301 return 0; 302 } 303 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req); 304 305 static enum sk_rst_reason mptcp_get_rst_reason(const struct sk_buff *skb) 306 { 307 const struct mptcp_ext *mpext = mptcp_get_ext(skb); 308 309 if (!mpext) 310 return SK_RST_REASON_NOT_SPECIFIED; 311 312 return sk_rst_convert_mptcp_reason(mpext->reset_reason); 313 } 314 315 static struct dst_entry *subflow_v4_route_req(const struct sock *sk, 316 struct sk_buff *skb, 317 struct flowi *fl, 318 struct request_sock *req, 319 u32 tw_isn) 320 { 321 struct dst_entry *dst; 322 int err; 323 324 tcp_rsk(req)->is_mptcp = 1; 325 subflow_init_req(req, sk); 326 327 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req, tw_isn); 328 if (!dst) 329 return NULL; 330 331 err = subflow_check_req(req, sk, skb); 332 if (err == 0) 333 return dst; 334 335 dst_release(dst); 336 if (!req->syncookie) 337 tcp_request_sock_ops.send_reset(sk, skb, 338 mptcp_get_rst_reason(skb)); 339 return NULL; 340 } 341 342 static void subflow_prep_synack(const struct sock *sk, struct request_sock *req, 343 struct tcp_fastopen_cookie *foc, 344 enum tcp_synack_type synack_type) 345 { 346 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 347 struct inet_request_sock *ireq = inet_rsk(req); 348 349 /* clear tstamp_ok, as needed depending on cookie */ 350 if (foc && foc->len > -1) 351 ireq->tstamp_ok = 0; 352 353 if (synack_type == TCP_SYNACK_FASTOPEN) 354 mptcp_fastopen_subflow_synack_set_params(subflow, req); 355 } 356 357 static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst, 358 struct flowi *fl, 359 struct request_sock *req, 360 struct tcp_fastopen_cookie *foc, 361 enum tcp_synack_type synack_type, 362 struct sk_buff *syn_skb) 363 { 364 subflow_prep_synack(sk, req, foc, synack_type); 365 366 return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc, 367 synack_type, syn_skb); 368 } 369 370 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 371 static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst, 372 struct flowi *fl, 373 struct request_sock *req, 374 struct tcp_fastopen_cookie *foc, 375 enum tcp_synack_type synack_type, 376 struct sk_buff *syn_skb) 377 { 378 subflow_prep_synack(sk, req, foc, synack_type); 379 380 return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc, 381 synack_type, syn_skb); 382 } 383 384 static struct dst_entry *subflow_v6_route_req(const struct sock *sk, 385 struct sk_buff *skb, 386 struct flowi *fl, 387 struct request_sock *req, 388 u32 tw_isn) 389 { 390 struct dst_entry *dst; 391 int err; 392 393 tcp_rsk(req)->is_mptcp = 1; 394 subflow_init_req(req, sk); 395 396 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req, tw_isn); 397 if (!dst) 398 return NULL; 399 400 err = subflow_check_req(req, sk, skb); 401 if (err == 0) 402 return dst; 403 404 dst_release(dst); 405 if (!req->syncookie) 406 tcp6_request_sock_ops.send_reset(sk, skb, 407 mptcp_get_rst_reason(skb)); 408 return NULL; 409 } 410 #endif 411 412 /* validate received truncated hmac and create hmac for third ACK */ 413 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow) 414 { 415 u8 hmac[SHA256_DIGEST_SIZE]; 416 u64 thmac; 417 418 subflow_generate_hmac(subflow->remote_key, subflow->local_key, 419 subflow->remote_nonce, subflow->local_nonce, 420 hmac); 421 422 thmac = get_unaligned_be64(hmac); 423 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n", 424 subflow, subflow->token, thmac, subflow->thmac); 425 426 return thmac == subflow->thmac; 427 } 428 429 void mptcp_subflow_reset(struct sock *ssk) 430 { 431 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 432 struct sock *sk = subflow->conn; 433 434 /* mptcp_mp_fail_no_response() can reach here on an already closed 435 * socket 436 */ 437 if (ssk->sk_state == TCP_CLOSE) 438 return; 439 440 /* must hold: tcp_done() could drop last reference on parent */ 441 sock_hold(sk); 442 443 mptcp_send_active_reset_reason(ssk); 444 tcp_done(ssk); 445 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags)) 446 mptcp_schedule_work(sk); 447 448 sock_put(sk); 449 } 450 451 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk) 452 { 453 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport; 454 } 455 456 void __mptcp_sync_state(struct sock *sk, int state) 457 { 458 struct mptcp_subflow_context *subflow; 459 struct mptcp_sock *msk = mptcp_sk(sk); 460 struct sock *ssk = msk->first; 461 462 subflow = mptcp_subflow_ctx(ssk); 463 __mptcp_propagate_sndbuf(sk, ssk); 464 if (!msk->rcvspace_init) 465 mptcp_rcv_space_init(msk, ssk); 466 467 if (sk->sk_state == TCP_SYN_SENT) { 468 /* subflow->idsn is always available is TCP_SYN_SENT state, 469 * even for the FASTOPEN scenarios 470 */ 471 WRITE_ONCE(msk->write_seq, subflow->idsn + 1); 472 WRITE_ONCE(msk->snd_nxt, msk->write_seq); 473 mptcp_set_state(sk, state); 474 sk->sk_state_change(sk); 475 } 476 } 477 478 static void subflow_set_remote_key(struct mptcp_sock *msk, 479 struct mptcp_subflow_context *subflow, 480 const struct mptcp_options_received *mp_opt) 481 { 482 /* active MPC subflow will reach here multiple times: 483 * at subflow_finish_connect() time and at 4th ack time 484 */ 485 if (subflow->remote_key_valid) 486 return; 487 488 subflow->remote_key_valid = 1; 489 subflow->remote_key = mp_opt->sndr_key; 490 mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn); 491 subflow->iasn++; 492 493 WRITE_ONCE(msk->remote_key, subflow->remote_key); 494 WRITE_ONCE(msk->ack_seq, subflow->iasn); 495 WRITE_ONCE(msk->can_ack, true); 496 atomic64_set(&msk->rcv_wnd_sent, subflow->iasn); 497 } 498 499 static void mptcp_propagate_state(struct sock *sk, struct sock *ssk, 500 struct mptcp_subflow_context *subflow, 501 const struct mptcp_options_received *mp_opt) 502 { 503 struct mptcp_sock *msk = mptcp_sk(sk); 504 505 mptcp_data_lock(sk); 506 if (mp_opt) { 507 /* Options are available only in the non fallback cases 508 * avoid updating rx path fields otherwise 509 */ 510 WRITE_ONCE(msk->snd_una, subflow->idsn + 1); 511 WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd); 512 subflow_set_remote_key(msk, subflow, mp_opt); 513 } 514 515 if (!sock_owned_by_user(sk)) { 516 __mptcp_sync_state(sk, ssk->sk_state); 517 } else { 518 msk->pending_state = ssk->sk_state; 519 __set_bit(MPTCP_SYNC_STATE, &msk->cb_flags); 520 } 521 mptcp_data_unlock(sk); 522 } 523 524 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 525 { 526 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 527 struct mptcp_options_received mp_opt; 528 struct sock *parent = subflow->conn; 529 struct mptcp_sock *msk; 530 531 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb); 532 533 /* be sure no special action on any packet other than syn-ack */ 534 if (subflow->conn_finished) 535 return; 536 537 msk = mptcp_sk(parent); 538 subflow->rel_write_seq = 1; 539 subflow->conn_finished = 1; 540 subflow->ssn_offset = TCP_SKB_CB(skb)->seq; 541 pr_debug("subflow=%p synack seq=%x\n", subflow, subflow->ssn_offset); 542 543 mptcp_get_options(skb, &mp_opt); 544 if (subflow->request_mptcp) { 545 if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) { 546 MPTCP_INC_STATS(sock_net(sk), 547 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); 548 mptcp_do_fallback(sk); 549 pr_fallback(msk); 550 goto fallback; 551 } 552 553 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD) 554 WRITE_ONCE(msk->csum_enabled, true); 555 if (mp_opt.deny_join_id0) 556 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 557 subflow->mp_capable = 1; 558 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK); 559 mptcp_finish_connect(sk); 560 mptcp_active_enable(parent); 561 mptcp_propagate_state(parent, sk, subflow, &mp_opt); 562 } else if (subflow->request_join) { 563 u8 hmac[SHA256_DIGEST_SIZE]; 564 565 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) { 566 subflow->reset_reason = MPTCP_RST_EMPTCP; 567 goto do_reset; 568 } 569 570 subflow->backup = mp_opt.backup; 571 subflow->thmac = mp_opt.thmac; 572 subflow->remote_nonce = mp_opt.nonce; 573 WRITE_ONCE(subflow->remote_id, mp_opt.join_id); 574 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d\n", 575 subflow, subflow->thmac, subflow->remote_nonce, 576 subflow->backup); 577 578 if (!subflow_thmac_valid(subflow)) { 579 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC); 580 subflow->reset_reason = MPTCP_RST_EMPTCP; 581 goto do_reset; 582 } 583 584 if (!mptcp_finish_join(sk)) 585 goto do_reset; 586 587 subflow_generate_hmac(subflow->local_key, subflow->remote_key, 588 subflow->local_nonce, 589 subflow->remote_nonce, 590 hmac); 591 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN); 592 593 subflow->mp_join = 1; 594 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX); 595 596 if (subflow->backup) 597 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKBACKUPRX); 598 599 if (subflow_use_different_dport(msk, sk)) { 600 pr_debug("synack inet_dport=%d %d\n", 601 ntohs(inet_sk(sk)->inet_dport), 602 ntohs(inet_sk(parent)->inet_dport)); 603 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX); 604 } 605 } else if (mptcp_check_fallback(sk)) { 606 /* It looks like MPTCP is blocked, while TCP is not */ 607 if (subflow->mpc_drop) 608 mptcp_active_disable(parent); 609 fallback: 610 mptcp_propagate_state(parent, sk, subflow, NULL); 611 } 612 return; 613 614 do_reset: 615 subflow->reset_transient = 0; 616 mptcp_subflow_reset(sk); 617 } 618 619 static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id) 620 { 621 WARN_ON_ONCE(local_id < 0 || local_id > 255); 622 WRITE_ONCE(subflow->local_id, local_id); 623 } 624 625 static int subflow_chk_local_id(struct sock *sk) 626 { 627 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 628 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 629 int err; 630 631 if (likely(subflow->local_id >= 0)) 632 return 0; 633 634 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk); 635 if (err < 0) 636 return err; 637 638 subflow_set_local_id(subflow, err); 639 subflow->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)sk); 640 641 return 0; 642 } 643 644 static int subflow_rebuild_header(struct sock *sk) 645 { 646 int err = subflow_chk_local_id(sk); 647 648 if (unlikely(err < 0)) 649 return err; 650 651 return inet_sk_rebuild_header(sk); 652 } 653 654 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 655 static int subflow_v6_rebuild_header(struct sock *sk) 656 { 657 int err = subflow_chk_local_id(sk); 658 659 if (unlikely(err < 0)) 660 return err; 661 662 return inet6_sk_rebuild_header(sk); 663 } 664 #endif 665 666 static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init; 667 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init; 668 669 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb) 670 { 671 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 672 673 pr_debug("subflow=%p\n", subflow); 674 675 /* Never answer to SYNs sent to broadcast or multicast */ 676 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 677 goto drop; 678 679 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops, 680 &subflow_request_sock_ipv4_ops, 681 sk, skb); 682 drop: 683 tcp_listendrop(sk); 684 return 0; 685 } 686 687 static void subflow_v4_req_destructor(struct request_sock *req) 688 { 689 subflow_req_destructor(req); 690 tcp_request_sock_ops.destructor(req); 691 } 692 693 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 694 static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init; 695 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init; 696 static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init; 697 static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init; 698 static struct proto tcpv6_prot_override __ro_after_init; 699 700 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb) 701 { 702 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 703 704 pr_debug("subflow=%p\n", subflow); 705 706 if (skb->protocol == htons(ETH_P_IP)) 707 return subflow_v4_conn_request(sk, skb); 708 709 if (!ipv6_unicast_destination(skb)) 710 goto drop; 711 712 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) { 713 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS); 714 return 0; 715 } 716 717 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops, 718 &subflow_request_sock_ipv6_ops, sk, skb); 719 720 drop: 721 tcp_listendrop(sk); 722 return 0; /* don't send reset */ 723 } 724 725 static void subflow_v6_req_destructor(struct request_sock *req) 726 { 727 subflow_req_destructor(req); 728 tcp6_request_sock_ops.destructor(req); 729 } 730 #endif 731 732 struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops, 733 struct sock *sk_listener, 734 bool attach_listener) 735 { 736 if (ops->family == AF_INET) 737 ops = &mptcp_subflow_v4_request_sock_ops; 738 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 739 else if (ops->family == AF_INET6) 740 ops = &mptcp_subflow_v6_request_sock_ops; 741 #endif 742 743 return inet_reqsk_alloc(ops, sk_listener, attach_listener); 744 } 745 EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc); 746 747 /* validate hmac received in third ACK */ 748 static bool subflow_hmac_valid(const struct request_sock *req, 749 const struct mptcp_options_received *mp_opt) 750 { 751 const struct mptcp_subflow_request_sock *subflow_req; 752 u8 hmac[SHA256_DIGEST_SIZE]; 753 struct mptcp_sock *msk; 754 755 subflow_req = mptcp_subflow_rsk(req); 756 msk = subflow_req->msk; 757 if (!msk) 758 return false; 759 760 subflow_generate_hmac(READ_ONCE(msk->remote_key), 761 READ_ONCE(msk->local_key), 762 subflow_req->remote_nonce, 763 subflow_req->local_nonce, hmac); 764 765 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN); 766 } 767 768 static void subflow_ulp_fallback(struct sock *sk, 769 struct mptcp_subflow_context *old_ctx) 770 { 771 struct inet_connection_sock *icsk = inet_csk(sk); 772 773 mptcp_subflow_tcp_fallback(sk, old_ctx); 774 icsk->icsk_ulp_ops = NULL; 775 rcu_assign_pointer(icsk->icsk_ulp_data, NULL); 776 tcp_sk(sk)->is_mptcp = 0; 777 778 mptcp_subflow_ops_undo_override(sk); 779 } 780 781 void mptcp_subflow_drop_ctx(struct sock *ssk) 782 { 783 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 784 785 if (!ctx) 786 return; 787 788 list_del(&mptcp_subflow_ctx(ssk)->node); 789 if (inet_csk(ssk)->icsk_ulp_ops) { 790 subflow_ulp_fallback(ssk, ctx); 791 if (ctx->conn) 792 sock_put(ctx->conn); 793 } 794 795 kfree_rcu(ctx, rcu); 796 } 797 798 void __mptcp_subflow_fully_established(struct mptcp_sock *msk, 799 struct mptcp_subflow_context *subflow, 800 const struct mptcp_options_received *mp_opt) 801 { 802 subflow_set_remote_key(msk, subflow, mp_opt); 803 WRITE_ONCE(subflow->fully_established, true); 804 WRITE_ONCE(msk->fully_established, true); 805 } 806 807 static struct sock *subflow_syn_recv_sock(const struct sock *sk, 808 struct sk_buff *skb, 809 struct request_sock *req, 810 struct dst_entry *dst, 811 struct request_sock *req_unhash, 812 bool *own_req) 813 { 814 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk); 815 struct mptcp_subflow_request_sock *subflow_req; 816 struct mptcp_options_received mp_opt; 817 bool fallback, fallback_is_fatal; 818 enum sk_rst_reason reason; 819 struct mptcp_sock *owner; 820 struct sock *child; 821 822 pr_debug("listener=%p, req=%p, conn=%p\n", listener, req, listener->conn); 823 824 /* After child creation we must look for MPC even when options 825 * are not parsed 826 */ 827 mp_opt.suboptions = 0; 828 829 /* hopefully temporary handling for MP_JOIN+syncookie */ 830 subflow_req = mptcp_subflow_rsk(req); 831 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join; 832 fallback = !tcp_rsk(req)->is_mptcp; 833 if (fallback) 834 goto create_child; 835 836 /* if the sk is MP_CAPABLE, we try to fetch the client key */ 837 if (subflow_req->mp_capable) { 838 /* we can receive and accept an in-window, out-of-order pkt, 839 * which may not carry the MP_CAPABLE opt even on mptcp enabled 840 * paths: always try to extract the peer key, and fallback 841 * for packets missing it. 842 * Even OoO DSS packets coming legitly after dropped or 843 * reordered MPC will cause fallback, but we don't have other 844 * options. 845 */ 846 mptcp_get_options(skb, &mp_opt); 847 if (!(mp_opt.suboptions & 848 (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK))) 849 fallback = true; 850 851 } else if (subflow_req->mp_join) { 852 mptcp_get_options(skb, &mp_opt); 853 if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) || 854 !subflow_hmac_valid(req, &mp_opt) || 855 !mptcp_can_accept_new_subflow(subflow_req->msk)) { 856 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC); 857 fallback = true; 858 } 859 } 860 861 create_child: 862 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, 863 req_unhash, own_req); 864 865 if (child && *own_req) { 866 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child); 867 868 tcp_rsk(req)->drop_req = false; 869 870 /* we need to fallback on ctx allocation failure and on pre-reqs 871 * checking above. In the latter scenario we additionally need 872 * to reset the context to non MPTCP status. 873 */ 874 if (!ctx || fallback) { 875 if (fallback_is_fatal) { 876 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); 877 goto dispose_child; 878 } 879 goto fallback; 880 } 881 882 /* ssk inherits options of listener sk */ 883 ctx->setsockopt_seq = listener->setsockopt_seq; 884 885 if (ctx->mp_capable) { 886 ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req); 887 if (!ctx->conn) 888 goto fallback; 889 890 ctx->subflow_id = 1; 891 owner = mptcp_sk(ctx->conn); 892 mptcp_pm_new_connection(owner, child, 1); 893 894 /* with OoO packets we can reach here without ingress 895 * mpc option 896 */ 897 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) { 898 mptcp_pm_fully_established(owner, child); 899 ctx->pm_notified = 1; 900 } 901 } else if (ctx->mp_join) { 902 owner = subflow_req->msk; 903 if (!owner) { 904 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); 905 goto dispose_child; 906 } 907 908 /* move the msk reference ownership to the subflow */ 909 subflow_req->msk = NULL; 910 ctx->conn = (struct sock *)owner; 911 912 if (subflow_use_different_sport(owner, sk)) { 913 pr_debug("ack inet_sport=%d %d\n", 914 ntohs(inet_sk(sk)->inet_sport), 915 ntohs(inet_sk((struct sock *)owner)->inet_sport)); 916 if (!mptcp_pm_sport_in_anno_list(owner, sk)) { 917 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX); 918 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); 919 goto dispose_child; 920 } 921 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX); 922 } 923 924 if (!mptcp_finish_join(child)) { 925 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(child); 926 927 subflow_add_reset_reason(skb, subflow->reset_reason); 928 goto dispose_child; 929 } 930 931 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX); 932 tcp_rsk(req)->drop_req = true; 933 } 934 } 935 936 /* check for expected invariant - should never trigger, just help 937 * catching earlier subtle bugs 938 */ 939 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp && 940 (!mptcp_subflow_ctx(child) || 941 !mptcp_subflow_ctx(child)->conn)); 942 return child; 943 944 dispose_child: 945 mptcp_subflow_drop_ctx(child); 946 tcp_rsk(req)->drop_req = true; 947 inet_csk_prepare_for_destroy_sock(child); 948 tcp_done(child); 949 reason = mptcp_get_rst_reason(skb); 950 req->rsk_ops->send_reset(sk, skb, reason); 951 952 /* The last child reference will be released by the caller */ 953 return child; 954 955 fallback: 956 if (fallback) 957 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK); 958 mptcp_subflow_drop_ctx(child); 959 return child; 960 } 961 962 static struct inet_connection_sock_af_ops subflow_specific __ro_after_init; 963 static struct proto tcp_prot_override __ro_after_init; 964 965 enum mapping_status { 966 MAPPING_OK, 967 MAPPING_INVALID, 968 MAPPING_EMPTY, 969 MAPPING_DATA_FIN, 970 MAPPING_DUMMY, 971 MAPPING_BAD_CSUM, 972 MAPPING_NODSS 973 }; 974 975 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn) 976 { 977 pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d\n", 978 ssn, subflow->map_subflow_seq, subflow->map_data_len); 979 } 980 981 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb) 982 { 983 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 984 unsigned int skb_consumed; 985 986 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq; 987 if (unlikely(skb_consumed >= skb->len)) { 988 DEBUG_NET_WARN_ON_ONCE(1); 989 return true; 990 } 991 992 return skb->len - skb_consumed <= subflow->map_data_len - 993 mptcp_subflow_get_map_offset(subflow); 994 } 995 996 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb) 997 { 998 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 999 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset; 1000 1001 if (unlikely(before(ssn, subflow->map_subflow_seq))) { 1002 /* Mapping covers data later in the subflow stream, 1003 * currently unsupported. 1004 */ 1005 dbg_bad_map(subflow, ssn); 1006 return false; 1007 } 1008 if (unlikely(!before(ssn, subflow->map_subflow_seq + 1009 subflow->map_data_len))) { 1010 /* Mapping does covers past subflow data, invalid */ 1011 dbg_bad_map(subflow, ssn); 1012 return false; 1013 } 1014 return true; 1015 } 1016 1017 static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb, 1018 bool csum_reqd) 1019 { 1020 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1021 u32 offset, seq, delta; 1022 __sum16 csum; 1023 int len; 1024 1025 if (!csum_reqd) 1026 return MAPPING_OK; 1027 1028 /* mapping already validated on previous traversal */ 1029 if (subflow->map_csum_len == subflow->map_data_len) 1030 return MAPPING_OK; 1031 1032 /* traverse the receive queue, ensuring it contains a full 1033 * DSS mapping and accumulating the related csum. 1034 * Preserve the accoumlate csum across multiple calls, to compute 1035 * the csum only once 1036 */ 1037 delta = subflow->map_data_len - subflow->map_csum_len; 1038 for (;;) { 1039 seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len; 1040 offset = seq - TCP_SKB_CB(skb)->seq; 1041 1042 /* if the current skb has not been accounted yet, csum its contents 1043 * up to the amount covered by the current DSS 1044 */ 1045 if (offset < skb->len) { 1046 __wsum csum; 1047 1048 len = min(skb->len - offset, delta); 1049 csum = skb_checksum(skb, offset, len, 0); 1050 subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum, 1051 subflow->map_csum_len); 1052 1053 delta -= len; 1054 subflow->map_csum_len += len; 1055 } 1056 if (delta == 0) 1057 break; 1058 1059 if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) { 1060 /* if this subflow is closed, the partial mapping 1061 * will be never completed; flush the pending skbs, so 1062 * that subflow_sched_work_if_closed() can kick in 1063 */ 1064 if (unlikely(ssk->sk_state == TCP_CLOSE)) 1065 while ((skb = skb_peek(&ssk->sk_receive_queue))) 1066 sk_eat_skb(ssk, skb); 1067 1068 /* not enough data to validate the csum */ 1069 return MAPPING_EMPTY; 1070 } 1071 1072 /* the DSS mapping for next skbs will be validated later, 1073 * when a get_mapping_status call will process such skb 1074 */ 1075 skb = skb->next; 1076 } 1077 1078 /* note that 'map_data_len' accounts only for the carried data, does 1079 * not include the eventual seq increment due to the data fin, 1080 * while the pseudo header requires the original DSS data len, 1081 * including that 1082 */ 1083 csum = __mptcp_make_csum(subflow->map_seq, 1084 subflow->map_subflow_seq, 1085 subflow->map_data_len + subflow->map_data_fin, 1086 subflow->map_data_csum); 1087 if (unlikely(csum)) { 1088 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR); 1089 return MAPPING_BAD_CSUM; 1090 } 1091 1092 subflow->valid_csum_seen = 1; 1093 return MAPPING_OK; 1094 } 1095 1096 static enum mapping_status get_mapping_status(struct sock *ssk, 1097 struct mptcp_sock *msk) 1098 { 1099 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1100 bool csum_reqd = READ_ONCE(msk->csum_enabled); 1101 struct mptcp_ext *mpext; 1102 struct sk_buff *skb; 1103 u16 data_len; 1104 u64 map_seq; 1105 1106 skb = skb_peek(&ssk->sk_receive_queue); 1107 if (!skb) 1108 return MAPPING_EMPTY; 1109 1110 if (mptcp_check_fallback(ssk)) 1111 return MAPPING_DUMMY; 1112 1113 mpext = mptcp_get_ext(skb); 1114 if (!mpext || !mpext->use_map) { 1115 if (!subflow->map_valid && !skb->len) { 1116 /* the TCP stack deliver 0 len FIN pkt to the receive 1117 * queue, that is the only 0len pkts ever expected here, 1118 * and we can admit no mapping only for 0 len pkts 1119 */ 1120 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1121 WARN_ONCE(1, "0len seq %d:%d flags %x", 1122 TCP_SKB_CB(skb)->seq, 1123 TCP_SKB_CB(skb)->end_seq, 1124 TCP_SKB_CB(skb)->tcp_flags); 1125 sk_eat_skb(ssk, skb); 1126 return MAPPING_EMPTY; 1127 } 1128 1129 /* If the required DSS has likely been dropped by a middlebox */ 1130 if (!subflow->map_valid) 1131 return MAPPING_NODSS; 1132 1133 goto validate_seq; 1134 } 1135 1136 trace_get_mapping_status(mpext); 1137 1138 data_len = mpext->data_len; 1139 if (data_len == 0) { 1140 pr_debug("infinite mapping received\n"); 1141 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX); 1142 return MAPPING_INVALID; 1143 } 1144 1145 if (mpext->data_fin == 1) { 1146 u64 data_fin_seq; 1147 1148 if (data_len == 1) { 1149 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq, 1150 mpext->dsn64); 1151 pr_debug("DATA_FIN with no payload seq=%llu\n", mpext->data_seq); 1152 if (subflow->map_valid) { 1153 /* A DATA_FIN might arrive in a DSS 1154 * option before the previous mapping 1155 * has been fully consumed. Continue 1156 * handling the existing mapping. 1157 */ 1158 skb_ext_del(skb, SKB_EXT_MPTCP); 1159 return MAPPING_OK; 1160 } 1161 1162 if (updated) 1163 mptcp_schedule_work((struct sock *)msk); 1164 1165 return MAPPING_DATA_FIN; 1166 } 1167 1168 data_fin_seq = mpext->data_seq + data_len - 1; 1169 1170 /* If mpext->data_seq is a 32-bit value, data_fin_seq must also 1171 * be limited to 32 bits. 1172 */ 1173 if (!mpext->dsn64) 1174 data_fin_seq &= GENMASK_ULL(31, 0); 1175 1176 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64); 1177 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d\n", 1178 data_fin_seq, mpext->dsn64); 1179 1180 /* Adjust for DATA_FIN using 1 byte of sequence space */ 1181 data_len--; 1182 } 1183 1184 map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64); 1185 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64); 1186 1187 if (subflow->map_valid) { 1188 /* Allow replacing only with an identical map */ 1189 if (subflow->map_seq == map_seq && 1190 subflow->map_subflow_seq == mpext->subflow_seq && 1191 subflow->map_data_len == data_len && 1192 subflow->map_csum_reqd == mpext->csum_reqd) { 1193 skb_ext_del(skb, SKB_EXT_MPTCP); 1194 goto validate_csum; 1195 } 1196 1197 /* If this skb data are fully covered by the current mapping, 1198 * the new map would need caching, which is not supported 1199 */ 1200 if (skb_is_fully_mapped(ssk, skb)) { 1201 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH); 1202 return MAPPING_INVALID; 1203 } 1204 1205 /* will validate the next map after consuming the current one */ 1206 goto validate_csum; 1207 } 1208 1209 subflow->map_seq = map_seq; 1210 subflow->map_subflow_seq = mpext->subflow_seq; 1211 subflow->map_data_len = data_len; 1212 subflow->map_valid = 1; 1213 subflow->map_data_fin = mpext->data_fin; 1214 subflow->mpc_map = mpext->mpc_map; 1215 subflow->map_csum_reqd = mpext->csum_reqd; 1216 subflow->map_csum_len = 0; 1217 subflow->map_data_csum = csum_unfold(mpext->csum); 1218 1219 /* Cfr RFC 8684 Section 3.3.0 */ 1220 if (unlikely(subflow->map_csum_reqd != csum_reqd)) 1221 return MAPPING_INVALID; 1222 1223 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n", 1224 subflow->map_seq, subflow->map_subflow_seq, 1225 subflow->map_data_len, subflow->map_csum_reqd, 1226 subflow->map_data_csum); 1227 1228 validate_seq: 1229 /* we revalidate valid mapping on new skb, because we must ensure 1230 * the current skb is completely covered by the available mapping 1231 */ 1232 if (!validate_mapping(ssk, skb)) { 1233 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH); 1234 return MAPPING_INVALID; 1235 } 1236 1237 skb_ext_del(skb, SKB_EXT_MPTCP); 1238 1239 validate_csum: 1240 return validate_data_csum(ssk, skb, csum_reqd); 1241 } 1242 1243 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb, 1244 u64 limit) 1245 { 1246 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1247 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN; 1248 struct tcp_sock *tp = tcp_sk(ssk); 1249 u32 offset, incr, avail_len; 1250 1251 offset = tp->copied_seq - TCP_SKB_CB(skb)->seq; 1252 if (WARN_ON_ONCE(offset > skb->len)) 1253 goto out; 1254 1255 avail_len = skb->len - offset; 1256 incr = limit >= avail_len ? avail_len + fin : limit; 1257 1258 pr_debug("discarding=%d len=%d offset=%d seq=%d\n", incr, skb->len, 1259 offset, subflow->map_subflow_seq); 1260 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA); 1261 tcp_sk(ssk)->copied_seq += incr; 1262 1263 out: 1264 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq)) 1265 sk_eat_skb(ssk, skb); 1266 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) 1267 subflow->map_valid = 0; 1268 } 1269 1270 static bool subflow_is_done(const struct sock *sk) 1271 { 1272 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE; 1273 } 1274 1275 /* sched mptcp worker for subflow cleanup if no more data is pending */ 1276 static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk) 1277 { 1278 struct sock *sk = (struct sock *)msk; 1279 1280 if (likely(ssk->sk_state != TCP_CLOSE && 1281 (ssk->sk_state != TCP_CLOSE_WAIT || 1282 inet_sk_state_load(sk) != TCP_ESTABLISHED))) 1283 return; 1284 1285 if (!skb_queue_empty(&ssk->sk_receive_queue)) 1286 return; 1287 1288 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) 1289 mptcp_schedule_work(sk); 1290 1291 /* when the fallback subflow closes the rx side, trigger a 'dummy' 1292 * ingress data fin, so that the msk state will follow along 1293 */ 1294 if (__mptcp_check_fallback(msk) && subflow_is_done(ssk) && 1295 msk->first == ssk && 1296 mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true)) 1297 mptcp_schedule_work(sk); 1298 } 1299 1300 static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk) 1301 { 1302 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1303 unsigned long fail_tout; 1304 1305 /* graceful failure can happen only on the MPC subflow */ 1306 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first))) 1307 return; 1308 1309 /* since the close timeout take precedence on the fail one, 1310 * no need to start the latter when the first is already set 1311 */ 1312 if (sock_flag((struct sock *)msk, SOCK_DEAD)) 1313 return; 1314 1315 /* we don't need extreme accuracy here, use a zero fail_tout as special 1316 * value meaning no fail timeout at all; 1317 */ 1318 fail_tout = jiffies + TCP_RTO_MAX; 1319 if (!fail_tout) 1320 fail_tout = 1; 1321 WRITE_ONCE(subflow->fail_tout, fail_tout); 1322 tcp_send_ack(ssk); 1323 1324 mptcp_reset_tout_timer(msk, subflow->fail_tout); 1325 } 1326 1327 static bool subflow_check_data_avail(struct sock *ssk) 1328 { 1329 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1330 enum mapping_status status; 1331 struct mptcp_sock *msk; 1332 struct sk_buff *skb; 1333 1334 if (!skb_peek(&ssk->sk_receive_queue)) 1335 WRITE_ONCE(subflow->data_avail, false); 1336 if (subflow->data_avail) 1337 return true; 1338 1339 msk = mptcp_sk(subflow->conn); 1340 for (;;) { 1341 u64 ack_seq; 1342 u64 old_ack; 1343 1344 status = get_mapping_status(ssk, msk); 1345 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue)); 1346 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY || 1347 status == MAPPING_BAD_CSUM || status == MAPPING_NODSS)) 1348 goto fallback; 1349 1350 if (status != MAPPING_OK) 1351 goto no_data; 1352 1353 skb = skb_peek(&ssk->sk_receive_queue); 1354 if (WARN_ON_ONCE(!skb)) 1355 goto no_data; 1356 1357 if (unlikely(!READ_ONCE(msk->can_ack))) 1358 goto fallback; 1359 1360 old_ack = READ_ONCE(msk->ack_seq); 1361 ack_seq = mptcp_subflow_get_mapped_dsn(subflow); 1362 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx\n", old_ack, 1363 ack_seq); 1364 if (unlikely(before64(ack_seq, old_ack))) { 1365 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq); 1366 continue; 1367 } 1368 1369 WRITE_ONCE(subflow->data_avail, true); 1370 break; 1371 } 1372 return true; 1373 1374 no_data: 1375 subflow_sched_work_if_closed(msk, ssk); 1376 return false; 1377 1378 fallback: 1379 if (!__mptcp_check_fallback(msk)) { 1380 /* RFC 8684 section 3.7. */ 1381 if (status == MAPPING_BAD_CSUM && 1382 (subflow->mp_join || subflow->valid_csum_seen)) { 1383 subflow->send_mp_fail = 1; 1384 1385 if (!READ_ONCE(msk->allow_infinite_fallback)) { 1386 subflow->reset_transient = 0; 1387 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX; 1388 goto reset; 1389 } 1390 mptcp_subflow_fail(msk, ssk); 1391 WRITE_ONCE(subflow->data_avail, true); 1392 return true; 1393 } 1394 1395 if (!READ_ONCE(msk->allow_infinite_fallback)) { 1396 /* fatal protocol error, close the socket. 1397 * subflow_error_report() will introduce the appropriate barriers 1398 */ 1399 subflow->reset_transient = 0; 1400 subflow->reset_reason = status == MAPPING_NODSS ? 1401 MPTCP_RST_EMIDDLEBOX : 1402 MPTCP_RST_EMPTCP; 1403 1404 reset: 1405 WRITE_ONCE(ssk->sk_err, EBADMSG); 1406 tcp_set_state(ssk, TCP_CLOSE); 1407 while ((skb = skb_peek(&ssk->sk_receive_queue))) 1408 sk_eat_skb(ssk, skb); 1409 mptcp_send_active_reset_reason(ssk); 1410 WRITE_ONCE(subflow->data_avail, false); 1411 return false; 1412 } 1413 1414 mptcp_do_fallback(ssk); 1415 } 1416 1417 skb = skb_peek(&ssk->sk_receive_queue); 1418 subflow->map_valid = 1; 1419 subflow->map_seq = READ_ONCE(msk->ack_seq); 1420 subflow->map_data_len = skb->len; 1421 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset; 1422 WRITE_ONCE(subflow->data_avail, true); 1423 return true; 1424 } 1425 1426 bool mptcp_subflow_data_available(struct sock *sk) 1427 { 1428 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1429 1430 /* check if current mapping is still valid */ 1431 if (subflow->map_valid && 1432 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) { 1433 subflow->map_valid = 0; 1434 WRITE_ONCE(subflow->data_avail, false); 1435 1436 pr_debug("Done with mapping: seq=%u data_len=%u\n", 1437 subflow->map_subflow_seq, 1438 subflow->map_data_len); 1439 } 1440 1441 return subflow_check_data_avail(sk); 1442 } 1443 1444 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy, 1445 * not the ssk one. 1446 * 1447 * In mptcp, rwin is about the mptcp-level connection data. 1448 * 1449 * Data that is still on the ssk rx queue can thus be ignored, 1450 * as far as mptcp peer is concerned that data is still inflight. 1451 * DSS ACK is updated when skb is moved to the mptcp rx queue. 1452 */ 1453 void mptcp_space(const struct sock *ssk, int *space, int *full_space) 1454 { 1455 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1456 const struct sock *sk = subflow->conn; 1457 1458 *space = __mptcp_space(sk); 1459 *full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf)); 1460 } 1461 1462 static void subflow_error_report(struct sock *ssk) 1463 { 1464 struct sock *sk = mptcp_subflow_ctx(ssk)->conn; 1465 1466 /* bail early if this is a no-op, so that we avoid introducing a 1467 * problematic lockdep dependency between TCP accept queue lock 1468 * and msk socket spinlock 1469 */ 1470 if (!sk->sk_socket) 1471 return; 1472 1473 mptcp_data_lock(sk); 1474 if (!sock_owned_by_user(sk)) 1475 __mptcp_error_report(sk); 1476 else 1477 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags); 1478 mptcp_data_unlock(sk); 1479 } 1480 1481 static void subflow_data_ready(struct sock *sk) 1482 { 1483 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1484 u16 state = 1 << inet_sk_state_load(sk); 1485 struct sock *parent = subflow->conn; 1486 struct mptcp_sock *msk; 1487 1488 trace_sk_data_ready(sk); 1489 1490 msk = mptcp_sk(parent); 1491 if (state & TCPF_LISTEN) { 1492 /* MPJ subflow are removed from accept queue before reaching here, 1493 * avoid stray wakeups 1494 */ 1495 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue)) 1496 return; 1497 1498 parent->sk_data_ready(parent); 1499 return; 1500 } 1501 1502 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && 1503 !subflow->mp_join && !(state & TCPF_CLOSE)); 1504 1505 if (mptcp_subflow_data_available(sk)) { 1506 mptcp_data_ready(parent, sk); 1507 1508 /* subflow-level lowat test are not relevant. 1509 * respect the msk-level threshold eventually mandating an immediate ack 1510 */ 1511 if (mptcp_data_avail(msk) < parent->sk_rcvlowat && 1512 (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss) 1513 inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW; 1514 } else if (unlikely(sk->sk_err)) { 1515 subflow_error_report(sk); 1516 } 1517 } 1518 1519 static void subflow_write_space(struct sock *ssk) 1520 { 1521 struct sock *sk = mptcp_subflow_ctx(ssk)->conn; 1522 1523 mptcp_propagate_sndbuf(sk, ssk); 1524 mptcp_write_space(sk); 1525 } 1526 1527 static const struct inet_connection_sock_af_ops * 1528 subflow_default_af_ops(struct sock *sk) 1529 { 1530 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1531 if (sk->sk_family == AF_INET6) 1532 return &subflow_v6_specific; 1533 #endif 1534 return &subflow_specific; 1535 } 1536 1537 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1538 void mptcpv6_handle_mapped(struct sock *sk, bool mapped) 1539 { 1540 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1541 struct inet_connection_sock *icsk = inet_csk(sk); 1542 const struct inet_connection_sock_af_ops *target; 1543 1544 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk); 1545 1546 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d\n", 1547 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped); 1548 1549 if (likely(icsk->icsk_af_ops == target)) 1550 return; 1551 1552 subflow->icsk_af_ops = icsk->icsk_af_ops; 1553 icsk->icsk_af_ops = target; 1554 } 1555 #endif 1556 1557 void mptcp_info2sockaddr(const struct mptcp_addr_info *info, 1558 struct sockaddr_storage *addr, 1559 unsigned short family) 1560 { 1561 memset(addr, 0, sizeof(*addr)); 1562 addr->ss_family = family; 1563 if (addr->ss_family == AF_INET) { 1564 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr; 1565 1566 if (info->family == AF_INET) 1567 in_addr->sin_addr = info->addr; 1568 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1569 else if (ipv6_addr_v4mapped(&info->addr6)) 1570 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3]; 1571 #endif 1572 in_addr->sin_port = info->port; 1573 } 1574 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1575 else if (addr->ss_family == AF_INET6) { 1576 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr; 1577 1578 if (info->family == AF_INET) 1579 ipv6_addr_set_v4mapped(info->addr.s_addr, 1580 &in6_addr->sin6_addr); 1581 else 1582 in6_addr->sin6_addr = info->addr6; 1583 in6_addr->sin6_port = info->port; 1584 } 1585 #endif 1586 } 1587 1588 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_pm_local *local, 1589 const struct mptcp_addr_info *remote) 1590 { 1591 struct mptcp_sock *msk = mptcp_sk(sk); 1592 struct mptcp_subflow_context *subflow; 1593 int local_id = local->addr.id; 1594 struct sockaddr_storage addr; 1595 int remote_id = remote->id; 1596 int err = -ENOTCONN; 1597 struct socket *sf; 1598 struct sock *ssk; 1599 u32 remote_token; 1600 int addrlen; 1601 1602 /* The userspace PM sent the request too early? */ 1603 if (!mptcp_is_fully_established(sk)) 1604 goto err_out; 1605 1606 err = mptcp_subflow_create_socket(sk, local->addr.family, &sf); 1607 if (err) { 1608 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCREATSKERR); 1609 pr_debug("msk=%p local=%d remote=%d create sock error: %d\n", 1610 msk, local_id, remote_id, err); 1611 goto err_out; 1612 } 1613 1614 ssk = sf->sk; 1615 subflow = mptcp_subflow_ctx(ssk); 1616 do { 1617 get_random_bytes(&subflow->local_nonce, sizeof(u32)); 1618 } while (!subflow->local_nonce); 1619 1620 /* if 'IPADDRANY', the ID will be set later, after the routing */ 1621 if (local->addr.family == AF_INET) { 1622 if (!local->addr.addr.s_addr) 1623 local_id = -1; 1624 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1625 } else if (sk->sk_family == AF_INET6) { 1626 if (ipv6_addr_any(&local->addr.addr6)) 1627 local_id = -1; 1628 #endif 1629 } 1630 1631 if (local_id >= 0) 1632 subflow_set_local_id(subflow, local_id); 1633 1634 subflow->remote_key_valid = 1; 1635 subflow->remote_key = READ_ONCE(msk->remote_key); 1636 subflow->local_key = READ_ONCE(msk->local_key); 1637 subflow->token = msk->token; 1638 mptcp_info2sockaddr(&local->addr, &addr, ssk->sk_family); 1639 1640 addrlen = sizeof(struct sockaddr_in); 1641 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1642 if (addr.ss_family == AF_INET6) 1643 addrlen = sizeof(struct sockaddr_in6); 1644 #endif 1645 ssk->sk_bound_dev_if = local->ifindex; 1646 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen); 1647 if (err) { 1648 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXBINDERR); 1649 pr_debug("msk=%p local=%d remote=%d bind error: %d\n", 1650 msk, local_id, remote_id, err); 1651 goto failed; 1652 } 1653 1654 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL); 1655 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d\n", msk, 1656 remote_token, local_id, remote_id); 1657 subflow->remote_token = remote_token; 1658 WRITE_ONCE(subflow->remote_id, remote_id); 1659 subflow->request_join = 1; 1660 subflow->request_bkup = !!(local->flags & MPTCP_PM_ADDR_FLAG_BACKUP); 1661 subflow->subflow_id = msk->subflow_id++; 1662 mptcp_info2sockaddr(remote, &addr, ssk->sk_family); 1663 1664 sock_hold(ssk); 1665 list_add_tail(&subflow->node, &msk->conn_list); 1666 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK); 1667 if (err && err != -EINPROGRESS) { 1668 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCONNECTERR); 1669 pr_debug("msk=%p local=%d remote=%d connect error: %d\n", 1670 msk, local_id, remote_id, err); 1671 goto failed_unlink; 1672 } 1673 1674 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTX); 1675 1676 /* discard the subflow socket */ 1677 mptcp_sock_graft(ssk, sk->sk_socket); 1678 iput(SOCK_INODE(sf)); 1679 WRITE_ONCE(msk->allow_infinite_fallback, false); 1680 mptcp_stop_tout_timer(sk); 1681 return 0; 1682 1683 failed_unlink: 1684 list_del(&subflow->node); 1685 sock_put(mptcp_subflow_tcp_sock(subflow)); 1686 1687 failed: 1688 subflow->disposable = 1; 1689 sock_release(sf); 1690 1691 err_out: 1692 /* we account subflows before the creation, and this failures will not 1693 * be caught by sk_state_change() 1694 */ 1695 mptcp_pm_close_subflow(msk); 1696 return err; 1697 } 1698 1699 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child) 1700 { 1701 #ifdef CONFIG_SOCK_CGROUP_DATA 1702 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data, 1703 *child_skcd = &child->sk_cgrp_data; 1704 1705 /* only the additional subflows created by kworkers have to be modified */ 1706 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) != 1707 cgroup_id(sock_cgroup_ptr(child_skcd))) { 1708 #ifdef CONFIG_MEMCG 1709 struct mem_cgroup *memcg = parent->sk_memcg; 1710 1711 mem_cgroup_sk_free(child); 1712 if (memcg && css_tryget(&memcg->css)) 1713 child->sk_memcg = memcg; 1714 #endif /* CONFIG_MEMCG */ 1715 1716 cgroup_sk_free(child_skcd); 1717 *child_skcd = *parent_skcd; 1718 cgroup_sk_clone(child_skcd); 1719 } 1720 #endif /* CONFIG_SOCK_CGROUP_DATA */ 1721 } 1722 1723 static void mptcp_subflow_ops_override(struct sock *ssk) 1724 { 1725 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1726 if (ssk->sk_prot == &tcpv6_prot) 1727 ssk->sk_prot = &tcpv6_prot_override; 1728 else 1729 #endif 1730 ssk->sk_prot = &tcp_prot_override; 1731 } 1732 1733 static void mptcp_subflow_ops_undo_override(struct sock *ssk) 1734 { 1735 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1736 if (ssk->sk_prot == &tcpv6_prot_override) 1737 ssk->sk_prot = &tcpv6_prot; 1738 else 1739 #endif 1740 ssk->sk_prot = &tcp_prot; 1741 } 1742 1743 int mptcp_subflow_create_socket(struct sock *sk, unsigned short family, 1744 struct socket **new_sock) 1745 { 1746 struct mptcp_subflow_context *subflow; 1747 struct net *net = sock_net(sk); 1748 struct socket *sf; 1749 int err; 1750 1751 /* un-accepted server sockets can reach here - on bad configuration 1752 * bail early to avoid greater trouble later 1753 */ 1754 if (unlikely(!sk->sk_socket)) 1755 return -EINVAL; 1756 1757 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf); 1758 if (err) 1759 return err; 1760 1761 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING); 1762 1763 err = security_mptcp_add_subflow(sk, sf->sk); 1764 if (err) 1765 goto err_free; 1766 1767 /* the newly created socket has to be in the same cgroup as its parent */ 1768 mptcp_attach_cgroup(sk, sf->sk); 1769 1770 /* kernel sockets do not by default acquire net ref, but TCP timer 1771 * needs it. 1772 * Update ns_tracker to current stack trace and refcounted tracker. 1773 */ 1774 sk_net_refcnt_upgrade(sf->sk); 1775 err = tcp_set_ulp(sf->sk, "mptcp"); 1776 if (err) 1777 goto err_free; 1778 1779 mptcp_sockopt_sync_locked(mptcp_sk(sk), sf->sk); 1780 release_sock(sf->sk); 1781 1782 /* the newly created socket really belongs to the owning MPTCP 1783 * socket, even if for additional subflows the allocation is performed 1784 * by a kernel workqueue. Adjust inode references, so that the 1785 * procfs/diag interfaces really show this one belonging to the correct 1786 * user. 1787 */ 1788 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino; 1789 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid; 1790 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid; 1791 1792 subflow = mptcp_subflow_ctx(sf->sk); 1793 pr_debug("subflow=%p\n", subflow); 1794 1795 *new_sock = sf; 1796 sock_hold(sk); 1797 subflow->conn = sk; 1798 mptcp_subflow_ops_override(sf->sk); 1799 1800 return 0; 1801 1802 err_free: 1803 release_sock(sf->sk); 1804 sock_release(sf); 1805 return err; 1806 } 1807 1808 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk, 1809 gfp_t priority) 1810 { 1811 struct inet_connection_sock *icsk = inet_csk(sk); 1812 struct mptcp_subflow_context *ctx; 1813 1814 ctx = kzalloc(sizeof(*ctx), priority); 1815 if (!ctx) 1816 return NULL; 1817 1818 rcu_assign_pointer(icsk->icsk_ulp_data, ctx); 1819 INIT_LIST_HEAD(&ctx->node); 1820 INIT_LIST_HEAD(&ctx->delegated_node); 1821 1822 pr_debug("subflow=%p\n", ctx); 1823 1824 ctx->tcp_sock = sk; 1825 WRITE_ONCE(ctx->local_id, -1); 1826 1827 return ctx; 1828 } 1829 1830 static void __subflow_state_change(struct sock *sk) 1831 { 1832 struct socket_wq *wq; 1833 1834 rcu_read_lock(); 1835 wq = rcu_dereference(sk->sk_wq); 1836 if (skwq_has_sleeper(wq)) 1837 wake_up_interruptible_all(&wq->wait); 1838 rcu_read_unlock(); 1839 } 1840 1841 static void subflow_state_change(struct sock *sk) 1842 { 1843 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1844 struct sock *parent = subflow->conn; 1845 struct mptcp_sock *msk; 1846 1847 __subflow_state_change(sk); 1848 1849 msk = mptcp_sk(parent); 1850 if (subflow_simultaneous_connect(sk)) { 1851 mptcp_do_fallback(sk); 1852 pr_fallback(msk); 1853 subflow->conn_finished = 1; 1854 mptcp_propagate_state(parent, sk, subflow, NULL); 1855 } 1856 1857 /* as recvmsg() does not acquire the subflow socket for ssk selection 1858 * a fin packet carrying a DSS can be unnoticed if we don't trigger 1859 * the data available machinery here. 1860 */ 1861 if (mptcp_subflow_data_available(sk)) 1862 mptcp_data_ready(parent, sk); 1863 else if (unlikely(sk->sk_err)) 1864 subflow_error_report(sk); 1865 1866 subflow_sched_work_if_closed(mptcp_sk(parent), sk); 1867 } 1868 1869 void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk) 1870 { 1871 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue; 1872 struct request_sock *req, *head, *tail; 1873 struct mptcp_subflow_context *subflow; 1874 struct sock *sk, *ssk; 1875 1876 /* Due to lock dependencies no relevant lock can be acquired under rskq_lock. 1877 * Splice the req list, so that accept() can not reach the pending ssk after 1878 * the listener socket is released below. 1879 */ 1880 spin_lock_bh(&queue->rskq_lock); 1881 head = queue->rskq_accept_head; 1882 tail = queue->rskq_accept_tail; 1883 queue->rskq_accept_head = NULL; 1884 queue->rskq_accept_tail = NULL; 1885 spin_unlock_bh(&queue->rskq_lock); 1886 1887 if (!head) 1888 return; 1889 1890 /* can't acquire the msk socket lock under the subflow one, 1891 * or will cause ABBA deadlock 1892 */ 1893 release_sock(listener_ssk); 1894 1895 for (req = head; req; req = req->dl_next) { 1896 ssk = req->sk; 1897 if (!sk_is_mptcp(ssk)) 1898 continue; 1899 1900 subflow = mptcp_subflow_ctx(ssk); 1901 if (!subflow || !subflow->conn) 1902 continue; 1903 1904 sk = subflow->conn; 1905 sock_hold(sk); 1906 1907 lock_sock_nested(sk, SINGLE_DEPTH_NESTING); 1908 __mptcp_unaccepted_force_close(sk); 1909 release_sock(sk); 1910 1911 /* lockdep will report a false positive ABBA deadlock 1912 * between cancel_work_sync and the listener socket. 1913 * The involved locks belong to different sockets WRT 1914 * the existing AB chain. 1915 * Using a per socket key is problematic as key 1916 * deregistration requires process context and must be 1917 * performed at socket disposal time, in atomic 1918 * context. 1919 * Just tell lockdep to consider the listener socket 1920 * released here. 1921 */ 1922 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_); 1923 mptcp_cancel_work(sk); 1924 mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_); 1925 1926 sock_put(sk); 1927 } 1928 1929 /* we are still under the listener msk socket lock */ 1930 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING); 1931 1932 /* restore the listener queue, to let the TCP code clean it up */ 1933 spin_lock_bh(&queue->rskq_lock); 1934 WARN_ON_ONCE(queue->rskq_accept_head); 1935 queue->rskq_accept_head = head; 1936 queue->rskq_accept_tail = tail; 1937 spin_unlock_bh(&queue->rskq_lock); 1938 } 1939 1940 static int subflow_ulp_init(struct sock *sk) 1941 { 1942 struct inet_connection_sock *icsk = inet_csk(sk); 1943 struct mptcp_subflow_context *ctx; 1944 struct tcp_sock *tp = tcp_sk(sk); 1945 int err = 0; 1946 1947 /* disallow attaching ULP to a socket unless it has been 1948 * created with sock_create_kern() 1949 */ 1950 if (!sk->sk_kern_sock) { 1951 err = -EOPNOTSUPP; 1952 goto out; 1953 } 1954 1955 ctx = subflow_create_ctx(sk, GFP_KERNEL); 1956 if (!ctx) { 1957 err = -ENOMEM; 1958 goto out; 1959 } 1960 1961 pr_debug("subflow=%p, family=%d\n", ctx, sk->sk_family); 1962 1963 tp->is_mptcp = 1; 1964 ctx->icsk_af_ops = icsk->icsk_af_ops; 1965 icsk->icsk_af_ops = subflow_default_af_ops(sk); 1966 ctx->tcp_state_change = sk->sk_state_change; 1967 ctx->tcp_error_report = sk->sk_error_report; 1968 1969 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable); 1970 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space); 1971 1972 sk->sk_data_ready = subflow_data_ready; 1973 sk->sk_write_space = subflow_write_space; 1974 sk->sk_state_change = subflow_state_change; 1975 sk->sk_error_report = subflow_error_report; 1976 out: 1977 return err; 1978 } 1979 1980 static void subflow_ulp_release(struct sock *ssk) 1981 { 1982 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 1983 bool release = true; 1984 struct sock *sk; 1985 1986 if (!ctx) 1987 return; 1988 1989 sk = ctx->conn; 1990 if (sk) { 1991 /* if the msk has been orphaned, keep the ctx 1992 * alive, will be freed by __mptcp_close_ssk(), 1993 * when the subflow is still unaccepted 1994 */ 1995 release = ctx->disposable || list_empty(&ctx->node); 1996 1997 /* inet_child_forget() does not call sk_state_change(), 1998 * explicitly trigger the socket close machinery 1999 */ 2000 if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, 2001 &mptcp_sk(sk)->flags)) 2002 mptcp_schedule_work(sk); 2003 sock_put(sk); 2004 } 2005 2006 mptcp_subflow_ops_undo_override(ssk); 2007 if (release) 2008 kfree_rcu(ctx, rcu); 2009 } 2010 2011 static void subflow_ulp_clone(const struct request_sock *req, 2012 struct sock *newsk, 2013 const gfp_t priority) 2014 { 2015 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 2016 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk); 2017 struct mptcp_subflow_context *new_ctx; 2018 2019 if (!tcp_rsk(req)->is_mptcp || 2020 (!subflow_req->mp_capable && !subflow_req->mp_join)) { 2021 subflow_ulp_fallback(newsk, old_ctx); 2022 return; 2023 } 2024 2025 new_ctx = subflow_create_ctx(newsk, priority); 2026 if (!new_ctx) { 2027 subflow_ulp_fallback(newsk, old_ctx); 2028 return; 2029 } 2030 2031 new_ctx->conn_finished = 1; 2032 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops; 2033 new_ctx->tcp_state_change = old_ctx->tcp_state_change; 2034 new_ctx->tcp_error_report = old_ctx->tcp_error_report; 2035 new_ctx->rel_write_seq = 1; 2036 2037 if (subflow_req->mp_capable) { 2038 /* see comments in subflow_syn_recv_sock(), MPTCP connection 2039 * is fully established only after we receive the remote key 2040 */ 2041 new_ctx->mp_capable = 1; 2042 new_ctx->local_key = subflow_req->local_key; 2043 new_ctx->token = subflow_req->token; 2044 new_ctx->ssn_offset = subflow_req->ssn_offset; 2045 new_ctx->idsn = subflow_req->idsn; 2046 2047 /* this is the first subflow, id is always 0 */ 2048 subflow_set_local_id(new_ctx, 0); 2049 } else if (subflow_req->mp_join) { 2050 new_ctx->ssn_offset = subflow_req->ssn_offset; 2051 new_ctx->mp_join = 1; 2052 WRITE_ONCE(new_ctx->fully_established, true); 2053 new_ctx->remote_key_valid = 1; 2054 new_ctx->backup = subflow_req->backup; 2055 new_ctx->request_bkup = subflow_req->request_bkup; 2056 WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id); 2057 new_ctx->token = subflow_req->token; 2058 new_ctx->thmac = subflow_req->thmac; 2059 2060 /* the subflow req id is valid, fetched via subflow_check_req() 2061 * and subflow_token_join_request() 2062 */ 2063 subflow_set_local_id(new_ctx, subflow_req->local_id); 2064 } 2065 } 2066 2067 static void tcp_release_cb_override(struct sock *ssk) 2068 { 2069 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 2070 long status; 2071 2072 /* process and clear all the pending actions, but leave the subflow into 2073 * the napi queue. To respect locking, only the same CPU that originated 2074 * the action can touch the list. mptcp_napi_poll will take care of it. 2075 */ 2076 status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0); 2077 if (status) 2078 mptcp_subflow_process_delegated(ssk, status); 2079 2080 tcp_release_cb(ssk); 2081 } 2082 2083 static int tcp_abort_override(struct sock *ssk, int err) 2084 { 2085 /* closing a listener subflow requires a great deal of care. 2086 * keep it simple and just prevent such operation 2087 */ 2088 if (inet_sk_state_load(ssk) == TCP_LISTEN) 2089 return -EINVAL; 2090 2091 return tcp_abort(ssk, err); 2092 } 2093 2094 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = { 2095 .name = "mptcp", 2096 .owner = THIS_MODULE, 2097 .init = subflow_ulp_init, 2098 .release = subflow_ulp_release, 2099 .clone = subflow_ulp_clone, 2100 }; 2101 2102 static int subflow_ops_init(struct request_sock_ops *subflow_ops) 2103 { 2104 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock); 2105 2106 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name, 2107 subflow_ops->obj_size, 0, 2108 SLAB_ACCOUNT | 2109 SLAB_TYPESAFE_BY_RCU, 2110 NULL); 2111 if (!subflow_ops->slab) 2112 return -ENOMEM; 2113 2114 return 0; 2115 } 2116 2117 void __init mptcp_subflow_init(void) 2118 { 2119 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops; 2120 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4"; 2121 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor; 2122 2123 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0) 2124 panic("MPTCP: failed to init subflow v4 request sock ops\n"); 2125 2126 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops; 2127 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req; 2128 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack; 2129 2130 subflow_specific = ipv4_specific; 2131 subflow_specific.conn_request = subflow_v4_conn_request; 2132 subflow_specific.syn_recv_sock = subflow_syn_recv_sock; 2133 subflow_specific.sk_rx_dst_set = subflow_finish_connect; 2134 subflow_specific.rebuild_header = subflow_rebuild_header; 2135 2136 tcp_prot_override = tcp_prot; 2137 tcp_prot_override.release_cb = tcp_release_cb_override; 2138 tcp_prot_override.diag_destroy = tcp_abort_override; 2139 2140 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 2141 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock 2142 * structures for v4 and v6 have the same size. It should not changed in 2143 * the future but better to make sure to be warned if it is no longer 2144 * the case. 2145 */ 2146 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock)); 2147 2148 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops; 2149 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6"; 2150 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor; 2151 2152 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0) 2153 panic("MPTCP: failed to init subflow v6 request sock ops\n"); 2154 2155 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops; 2156 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req; 2157 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack; 2158 2159 subflow_v6_specific = ipv6_specific; 2160 subflow_v6_specific.conn_request = subflow_v6_conn_request; 2161 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock; 2162 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect; 2163 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header; 2164 2165 subflow_v6m_specific = subflow_v6_specific; 2166 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit; 2167 subflow_v6m_specific.send_check = ipv4_specific.send_check; 2168 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len; 2169 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced; 2170 subflow_v6m_specific.rebuild_header = subflow_rebuild_header; 2171 2172 tcpv6_prot_override = tcpv6_prot; 2173 tcpv6_prot_override.release_cb = tcp_release_cb_override; 2174 tcpv6_prot_override.diag_destroy = tcp_abort_override; 2175 #endif 2176 2177 mptcp_diag_subflow_init(&subflow_ulp_ops); 2178 2179 if (tcp_register_ulp(&subflow_ulp_ops) != 0) 2180 panic("MPTCP: failed to register subflows to ULP\n"); 2181 } 2182