1 // SPDX-License-Identifier: GPL-2.0 2 /* Multipath TCP 3 * 4 * Copyright (c) 2017 - 2019, Intel Corporation. 5 */ 6 7 #define pr_fmt(fmt) "MPTCP: " fmt 8 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/netdevice.h> 12 #include <crypto/algapi.h> 13 #include <crypto/sha2.h> 14 #include <net/sock.h> 15 #include <net/inet_common.h> 16 #include <net/inet_hashtables.h> 17 #include <net/protocol.h> 18 #include <net/tcp.h> 19 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 20 #include <net/ip6_route.h> 21 #include <net/transp_v6.h> 22 #endif 23 #include <net/mptcp.h> 24 #include <uapi/linux/mptcp.h> 25 #include "protocol.h" 26 #include "mib.h" 27 28 #include <trace/events/mptcp.h> 29 #include <trace/events/sock.h> 30 31 static void mptcp_subflow_ops_undo_override(struct sock *ssk); 32 33 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req, 34 enum linux_mptcp_mib_field field) 35 { 36 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field); 37 } 38 39 static void subflow_req_destructor(struct request_sock *req) 40 { 41 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 42 43 pr_debug("subflow_req=%p", subflow_req); 44 45 if (subflow_req->msk) 46 sock_put((struct sock *)subflow_req->msk); 47 48 mptcp_token_destroy_request(req); 49 } 50 51 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2, 52 void *hmac) 53 { 54 u8 msg[8]; 55 56 put_unaligned_be32(nonce1, &msg[0]); 57 put_unaligned_be32(nonce2, &msg[4]); 58 59 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac); 60 } 61 62 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk) 63 { 64 return mptcp_is_fully_established((void *)msk) && 65 ((mptcp_pm_is_userspace(msk) && 66 mptcp_userspace_pm_active(msk)) || 67 READ_ONCE(msk->pm.accept_subflow)); 68 } 69 70 /* validate received token and create truncated hmac and nonce for SYN-ACK */ 71 static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req) 72 { 73 struct mptcp_sock *msk = subflow_req->msk; 74 u8 hmac[SHA256_DIGEST_SIZE]; 75 76 get_random_bytes(&subflow_req->local_nonce, sizeof(u32)); 77 78 subflow_generate_hmac(msk->local_key, 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; 103 104 return msk; 105 } 106 107 static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener) 108 { 109 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 110 111 subflow_req->mp_capable = 0; 112 subflow_req->mp_join = 0; 113 subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener)); 114 subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener)); 115 subflow_req->msk = NULL; 116 mptcp_token_init_request(req); 117 } 118 119 static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk) 120 { 121 return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport; 122 } 123 124 static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason) 125 { 126 struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 127 128 if (mpext) { 129 memset(mpext, 0, sizeof(*mpext)); 130 mpext->reset_reason = reason; 131 } 132 } 133 134 /* Init mptcp request socket. 135 * 136 * Returns an error code if a JOIN has failed and a TCP reset 137 * should be sent. 138 */ 139 static int subflow_check_req(struct request_sock *req, 140 const struct sock *sk_listener, 141 struct sk_buff *skb) 142 { 143 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 144 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 145 struct mptcp_options_received mp_opt; 146 bool opt_mp_capable, opt_mp_join; 147 148 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener); 149 150 #ifdef CONFIG_TCP_MD5SIG 151 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of 152 * TCP option space. 153 */ 154 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) 155 return -EINVAL; 156 #endif 157 158 mptcp_get_options(skb, &mp_opt); 159 160 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC); 161 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ); 162 if (opt_mp_capable) { 163 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE); 164 165 if (opt_mp_join) 166 return 0; 167 } else if (opt_mp_join) { 168 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX); 169 } 170 171 if (opt_mp_capable && listener->request_mptcp) { 172 int err, retries = MPTCP_TOKEN_MAX_RETRIES; 173 174 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 175 again: 176 do { 177 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key)); 178 } while (subflow_req->local_key == 0); 179 180 if (unlikely(req->syncookie)) { 181 mptcp_crypto_key_sha(subflow_req->local_key, 182 &subflow_req->token, 183 &subflow_req->idsn); 184 if (mptcp_token_exists(subflow_req->token)) { 185 if (retries-- > 0) 186 goto again; 187 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT); 188 } else { 189 subflow_req->mp_capable = 1; 190 } 191 return 0; 192 } 193 194 err = mptcp_token_new_request(req); 195 if (err == 0) 196 subflow_req->mp_capable = 1; 197 else if (retries-- > 0) 198 goto again; 199 else 200 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT); 201 202 } else if (opt_mp_join && listener->request_mptcp) { 203 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 204 subflow_req->mp_join = 1; 205 subflow_req->backup = mp_opt.backup; 206 subflow_req->remote_id = mp_opt.join_id; 207 subflow_req->token = mp_opt.token; 208 subflow_req->remote_nonce = mp_opt.nonce; 209 subflow_req->msk = subflow_token_join_request(req); 210 211 /* Can't fall back to TCP in this case. */ 212 if (!subflow_req->msk) { 213 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); 214 return -EPERM; 215 } 216 217 if (subflow_use_different_sport(subflow_req->msk, sk_listener)) { 218 pr_debug("syn inet_sport=%d %d", 219 ntohs(inet_sk(sk_listener)->inet_sport), 220 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport)); 221 if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) { 222 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX); 223 return -EPERM; 224 } 225 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX); 226 } 227 228 subflow_req_create_thmac(subflow_req); 229 230 if (unlikely(req->syncookie)) { 231 if (mptcp_can_accept_new_subflow(subflow_req->msk)) 232 subflow_init_req_cookie_join_save(subflow_req, skb); 233 else 234 return -EPERM; 235 } 236 237 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token, 238 subflow_req->remote_nonce, subflow_req->msk); 239 } 240 241 return 0; 242 } 243 244 int mptcp_subflow_init_cookie_req(struct request_sock *req, 245 const struct sock *sk_listener, 246 struct sk_buff *skb) 247 { 248 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 249 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 250 struct mptcp_options_received mp_opt; 251 bool opt_mp_capable, opt_mp_join; 252 int err; 253 254 subflow_init_req(req, sk_listener); 255 mptcp_get_options(skb, &mp_opt); 256 257 opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC); 258 opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ); 259 if (opt_mp_capable && opt_mp_join) 260 return -EINVAL; 261 262 if (opt_mp_capable && listener->request_mptcp) { 263 if (mp_opt.sndr_key == 0) 264 return -EINVAL; 265 266 subflow_req->local_key = mp_opt.rcvr_key; 267 err = mptcp_token_new_request(req); 268 if (err) 269 return err; 270 271 subflow_req->mp_capable = 1; 272 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 273 } else if (opt_mp_join && listener->request_mptcp) { 274 if (!mptcp_token_join_cookie_init_state(subflow_req, skb)) 275 return -EINVAL; 276 277 subflow_req->mp_join = 1; 278 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 279 } 280 281 return 0; 282 } 283 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req); 284 285 static struct dst_entry *subflow_v4_route_req(const struct sock *sk, 286 struct sk_buff *skb, 287 struct flowi *fl, 288 struct request_sock *req) 289 { 290 struct dst_entry *dst; 291 int err; 292 293 tcp_rsk(req)->is_mptcp = 1; 294 subflow_init_req(req, sk); 295 296 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req); 297 if (!dst) 298 return NULL; 299 300 err = subflow_check_req(req, sk, skb); 301 if (err == 0) 302 return dst; 303 304 dst_release(dst); 305 if (!req->syncookie) 306 tcp_request_sock_ops.send_reset(sk, skb); 307 return NULL; 308 } 309 310 static void subflow_prep_synack(const struct sock *sk, struct request_sock *req, 311 struct tcp_fastopen_cookie *foc, 312 enum tcp_synack_type synack_type) 313 { 314 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 315 struct inet_request_sock *ireq = inet_rsk(req); 316 317 /* clear tstamp_ok, as needed depending on cookie */ 318 if (foc && foc->len > -1) 319 ireq->tstamp_ok = 0; 320 321 if (synack_type == TCP_SYNACK_FASTOPEN) 322 mptcp_fastopen_subflow_synack_set_params(subflow, req); 323 } 324 325 static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst, 326 struct flowi *fl, 327 struct request_sock *req, 328 struct tcp_fastopen_cookie *foc, 329 enum tcp_synack_type synack_type, 330 struct sk_buff *syn_skb) 331 { 332 subflow_prep_synack(sk, req, foc, synack_type); 333 334 return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc, 335 synack_type, syn_skb); 336 } 337 338 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 339 static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst, 340 struct flowi *fl, 341 struct request_sock *req, 342 struct tcp_fastopen_cookie *foc, 343 enum tcp_synack_type synack_type, 344 struct sk_buff *syn_skb) 345 { 346 subflow_prep_synack(sk, req, foc, synack_type); 347 348 return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc, 349 synack_type, syn_skb); 350 } 351 352 static struct dst_entry *subflow_v6_route_req(const struct sock *sk, 353 struct sk_buff *skb, 354 struct flowi *fl, 355 struct request_sock *req) 356 { 357 struct dst_entry *dst; 358 int err; 359 360 tcp_rsk(req)->is_mptcp = 1; 361 subflow_init_req(req, sk); 362 363 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req); 364 if (!dst) 365 return NULL; 366 367 err = subflow_check_req(req, sk, skb); 368 if (err == 0) 369 return dst; 370 371 dst_release(dst); 372 if (!req->syncookie) 373 tcp6_request_sock_ops.send_reset(sk, skb); 374 return NULL; 375 } 376 #endif 377 378 /* validate received truncated hmac and create hmac for third ACK */ 379 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow) 380 { 381 u8 hmac[SHA256_DIGEST_SIZE]; 382 u64 thmac; 383 384 subflow_generate_hmac(subflow->remote_key, subflow->local_key, 385 subflow->remote_nonce, subflow->local_nonce, 386 hmac); 387 388 thmac = get_unaligned_be64(hmac); 389 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n", 390 subflow, subflow->token, thmac, subflow->thmac); 391 392 return thmac == subflow->thmac; 393 } 394 395 void mptcp_subflow_reset(struct sock *ssk) 396 { 397 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 398 struct sock *sk = subflow->conn; 399 400 /* must hold: tcp_done() could drop last reference on parent */ 401 sock_hold(sk); 402 403 tcp_set_state(ssk, TCP_CLOSE); 404 tcp_send_active_reset(ssk, GFP_ATOMIC); 405 tcp_done(ssk); 406 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) && 407 schedule_work(&mptcp_sk(sk)->work)) 408 return; /* worker will put sk for us */ 409 410 sock_put(sk); 411 } 412 413 static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk) 414 { 415 return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport; 416 } 417 418 void __mptcp_set_connected(struct sock *sk) 419 { 420 if (sk->sk_state == TCP_SYN_SENT) { 421 inet_sk_state_store(sk, TCP_ESTABLISHED); 422 sk->sk_state_change(sk); 423 } 424 } 425 426 static void mptcp_set_connected(struct sock *sk) 427 { 428 mptcp_data_lock(sk); 429 if (!sock_owned_by_user(sk)) 430 __mptcp_set_connected(sk); 431 else 432 __set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->cb_flags); 433 mptcp_data_unlock(sk); 434 } 435 436 static void subflow_set_remote_key(struct mptcp_sock *msk, 437 struct mptcp_subflow_context *subflow, 438 const struct mptcp_options_received *mp_opt) 439 { 440 /* active MPC subflow will reach here multiple times: 441 * at subflow_finish_connect() time and at 4th ack time 442 */ 443 if (subflow->remote_key_valid) 444 return; 445 446 subflow->remote_key_valid = 1; 447 subflow->remote_key = mp_opt->sndr_key; 448 mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn); 449 subflow->iasn++; 450 451 WRITE_ONCE(msk->remote_key, subflow->remote_key); 452 WRITE_ONCE(msk->ack_seq, subflow->iasn); 453 WRITE_ONCE(msk->can_ack, true); 454 atomic64_set(&msk->rcv_wnd_sent, subflow->iasn); 455 } 456 457 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 458 { 459 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 460 struct mptcp_options_received mp_opt; 461 struct sock *parent = subflow->conn; 462 struct mptcp_sock *msk; 463 464 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb); 465 466 /* be sure no special action on any packet other than syn-ack */ 467 if (subflow->conn_finished) 468 return; 469 470 msk = mptcp_sk(parent); 471 mptcp_propagate_sndbuf(parent, sk); 472 subflow->rel_write_seq = 1; 473 subflow->conn_finished = 1; 474 subflow->ssn_offset = TCP_SKB_CB(skb)->seq; 475 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset); 476 477 mptcp_get_options(skb, &mp_opt); 478 if (subflow->request_mptcp) { 479 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) { 480 MPTCP_INC_STATS(sock_net(sk), 481 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); 482 mptcp_do_fallback(sk); 483 pr_fallback(msk); 484 goto fallback; 485 } 486 487 if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD) 488 WRITE_ONCE(msk->csum_enabled, true); 489 if (mp_opt.deny_join_id0) 490 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 491 subflow->mp_capable = 1; 492 subflow_set_remote_key(msk, subflow, &mp_opt); 493 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK); 494 mptcp_finish_connect(sk); 495 mptcp_set_connected(parent); 496 } else if (subflow->request_join) { 497 u8 hmac[SHA256_DIGEST_SIZE]; 498 499 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) { 500 subflow->reset_reason = MPTCP_RST_EMPTCP; 501 goto do_reset; 502 } 503 504 subflow->backup = mp_opt.backup; 505 subflow->thmac = mp_opt.thmac; 506 subflow->remote_nonce = mp_opt.nonce; 507 subflow->remote_id = mp_opt.join_id; 508 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d", 509 subflow, subflow->thmac, subflow->remote_nonce, 510 subflow->backup); 511 512 if (!subflow_thmac_valid(subflow)) { 513 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC); 514 subflow->reset_reason = MPTCP_RST_EMPTCP; 515 goto do_reset; 516 } 517 518 if (!mptcp_finish_join(sk)) 519 goto do_reset; 520 521 subflow_generate_hmac(subflow->local_key, subflow->remote_key, 522 subflow->local_nonce, 523 subflow->remote_nonce, 524 hmac); 525 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN); 526 527 subflow->mp_join = 1; 528 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX); 529 530 if (subflow_use_different_dport(msk, sk)) { 531 pr_debug("synack inet_dport=%d %d", 532 ntohs(inet_sk(sk)->inet_dport), 533 ntohs(inet_sk(parent)->inet_dport)); 534 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX); 535 } 536 } else if (mptcp_check_fallback(sk)) { 537 fallback: 538 mptcp_rcv_space_init(msk, sk); 539 mptcp_set_connected(parent); 540 } 541 return; 542 543 do_reset: 544 subflow->reset_transient = 0; 545 mptcp_subflow_reset(sk); 546 } 547 548 static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id) 549 { 550 subflow->local_id = local_id; 551 subflow->local_id_valid = 1; 552 } 553 554 static int subflow_chk_local_id(struct sock *sk) 555 { 556 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 557 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 558 int err; 559 560 if (likely(subflow->local_id_valid)) 561 return 0; 562 563 err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk); 564 if (err < 0) 565 return err; 566 567 subflow_set_local_id(subflow, err); 568 return 0; 569 } 570 571 static int subflow_rebuild_header(struct sock *sk) 572 { 573 int err = subflow_chk_local_id(sk); 574 575 if (unlikely(err < 0)) 576 return err; 577 578 return inet_sk_rebuild_header(sk); 579 } 580 581 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 582 static int subflow_v6_rebuild_header(struct sock *sk) 583 { 584 int err = subflow_chk_local_id(sk); 585 586 if (unlikely(err < 0)) 587 return err; 588 589 return inet6_sk_rebuild_header(sk); 590 } 591 #endif 592 593 static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init; 594 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init; 595 596 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb) 597 { 598 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 599 600 pr_debug("subflow=%p", subflow); 601 602 /* Never answer to SYNs sent to broadcast or multicast */ 603 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 604 goto drop; 605 606 return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops, 607 &subflow_request_sock_ipv4_ops, 608 sk, skb); 609 drop: 610 tcp_listendrop(sk); 611 return 0; 612 } 613 614 static void subflow_v4_req_destructor(struct request_sock *req) 615 { 616 subflow_req_destructor(req); 617 tcp_request_sock_ops.destructor(req); 618 } 619 620 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 621 static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init; 622 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init; 623 static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init; 624 static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init; 625 static struct proto tcpv6_prot_override; 626 627 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb) 628 { 629 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 630 631 pr_debug("subflow=%p", subflow); 632 633 if (skb->protocol == htons(ETH_P_IP)) 634 return subflow_v4_conn_request(sk, skb); 635 636 if (!ipv6_unicast_destination(skb)) 637 goto drop; 638 639 if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) { 640 __IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS); 641 return 0; 642 } 643 644 return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops, 645 &subflow_request_sock_ipv6_ops, sk, skb); 646 647 drop: 648 tcp_listendrop(sk); 649 return 0; /* don't send reset */ 650 } 651 652 static void subflow_v6_req_destructor(struct request_sock *req) 653 { 654 subflow_req_destructor(req); 655 tcp6_request_sock_ops.destructor(req); 656 } 657 #endif 658 659 struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops, 660 struct sock *sk_listener, 661 bool attach_listener) 662 { 663 if (ops->family == AF_INET) 664 ops = &mptcp_subflow_v4_request_sock_ops; 665 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 666 else if (ops->family == AF_INET6) 667 ops = &mptcp_subflow_v6_request_sock_ops; 668 #endif 669 670 return inet_reqsk_alloc(ops, sk_listener, attach_listener); 671 } 672 EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc); 673 674 /* validate hmac received in third ACK */ 675 static bool subflow_hmac_valid(const struct request_sock *req, 676 const struct mptcp_options_received *mp_opt) 677 { 678 const struct mptcp_subflow_request_sock *subflow_req; 679 u8 hmac[SHA256_DIGEST_SIZE]; 680 struct mptcp_sock *msk; 681 682 subflow_req = mptcp_subflow_rsk(req); 683 msk = subflow_req->msk; 684 if (!msk) 685 return false; 686 687 subflow_generate_hmac(msk->remote_key, msk->local_key, 688 subflow_req->remote_nonce, 689 subflow_req->local_nonce, hmac); 690 691 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN); 692 } 693 694 static void mptcp_force_close(struct sock *sk) 695 { 696 /* the msk is not yet exposed to user-space */ 697 inet_sk_state_store(sk, TCP_CLOSE); 698 sk_common_release(sk); 699 } 700 701 static void subflow_ulp_fallback(struct sock *sk, 702 struct mptcp_subflow_context *old_ctx) 703 { 704 struct inet_connection_sock *icsk = inet_csk(sk); 705 706 mptcp_subflow_tcp_fallback(sk, old_ctx); 707 icsk->icsk_ulp_ops = NULL; 708 rcu_assign_pointer(icsk->icsk_ulp_data, NULL); 709 tcp_sk(sk)->is_mptcp = 0; 710 711 mptcp_subflow_ops_undo_override(sk); 712 } 713 714 static void subflow_drop_ctx(struct sock *ssk) 715 { 716 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 717 718 if (!ctx) 719 return; 720 721 subflow_ulp_fallback(ssk, ctx); 722 if (ctx->conn) 723 sock_put(ctx->conn); 724 725 kfree_rcu(ctx, rcu); 726 } 727 728 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow, 729 const struct mptcp_options_received *mp_opt) 730 { 731 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 732 733 subflow_set_remote_key(msk, subflow, mp_opt); 734 subflow->fully_established = 1; 735 WRITE_ONCE(msk->fully_established, true); 736 737 if (subflow->is_mptfo) 738 mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt); 739 } 740 741 static struct sock *subflow_syn_recv_sock(const struct sock *sk, 742 struct sk_buff *skb, 743 struct request_sock *req, 744 struct dst_entry *dst, 745 struct request_sock *req_unhash, 746 bool *own_req) 747 { 748 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk); 749 struct mptcp_subflow_request_sock *subflow_req; 750 struct mptcp_options_received mp_opt; 751 bool fallback, fallback_is_fatal; 752 struct sock *new_msk = NULL; 753 struct sock *child; 754 755 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn); 756 757 /* After child creation we must look for MPC even when options 758 * are not parsed 759 */ 760 mp_opt.suboptions = 0; 761 762 /* hopefully temporary handling for MP_JOIN+syncookie */ 763 subflow_req = mptcp_subflow_rsk(req); 764 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join; 765 fallback = !tcp_rsk(req)->is_mptcp; 766 if (fallback) 767 goto create_child; 768 769 /* if the sk is MP_CAPABLE, we try to fetch the client key */ 770 if (subflow_req->mp_capable) { 771 /* we can receive and accept an in-window, out-of-order pkt, 772 * which may not carry the MP_CAPABLE opt even on mptcp enabled 773 * paths: always try to extract the peer key, and fallback 774 * for packets missing it. 775 * Even OoO DSS packets coming legitly after dropped or 776 * reordered MPC will cause fallback, but we don't have other 777 * options. 778 */ 779 mptcp_get_options(skb, &mp_opt); 780 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) { 781 fallback = true; 782 goto create_child; 783 } 784 785 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req); 786 if (!new_msk) 787 fallback = true; 788 } else if (subflow_req->mp_join) { 789 mptcp_get_options(skb, &mp_opt); 790 if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) || 791 !subflow_hmac_valid(req, &mp_opt) || 792 !mptcp_can_accept_new_subflow(subflow_req->msk)) { 793 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC); 794 fallback = true; 795 } 796 } 797 798 create_child: 799 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, 800 req_unhash, own_req); 801 802 if (child && *own_req) { 803 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child); 804 805 tcp_rsk(req)->drop_req = false; 806 807 /* we need to fallback on ctx allocation failure and on pre-reqs 808 * checking above. In the latter scenario we additionally need 809 * to reset the context to non MPTCP status. 810 */ 811 if (!ctx || fallback) { 812 if (fallback_is_fatal) { 813 subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); 814 goto dispose_child; 815 } 816 817 if (new_msk) 818 mptcp_copy_inaddrs(new_msk, child); 819 subflow_drop_ctx(child); 820 goto out; 821 } 822 823 /* ssk inherits options of listener sk */ 824 ctx->setsockopt_seq = listener->setsockopt_seq; 825 826 if (ctx->mp_capable) { 827 /* this can't race with mptcp_close(), as the msk is 828 * not yet exposted to user-space 829 */ 830 inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED); 831 832 /* record the newly created socket as the first msk 833 * subflow, but don't link it yet into conn_list 834 */ 835 WRITE_ONCE(mptcp_sk(new_msk)->first, child); 836 837 /* new mpc subflow takes ownership of the newly 838 * created mptcp socket 839 */ 840 mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq; 841 mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1); 842 mptcp_token_accept(subflow_req, mptcp_sk(new_msk)); 843 ctx->conn = new_msk; 844 new_msk = NULL; 845 846 /* set msk addresses early to ensure mptcp_pm_get_local_id() 847 * uses the correct data 848 */ 849 mptcp_copy_inaddrs(ctx->conn, child); 850 851 /* with OoO packets we can reach here without ingress 852 * mpc option 853 */ 854 if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) 855 mptcp_subflow_fully_established(ctx, &mp_opt); 856 } else if (ctx->mp_join) { 857 struct mptcp_sock *owner; 858 859 owner = subflow_req->msk; 860 if (!owner) { 861 subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); 862 goto dispose_child; 863 } 864 865 /* move the msk reference ownership to the subflow */ 866 subflow_req->msk = NULL; 867 ctx->conn = (struct sock *)owner; 868 869 if (subflow_use_different_sport(owner, sk)) { 870 pr_debug("ack inet_sport=%d %d", 871 ntohs(inet_sk(sk)->inet_sport), 872 ntohs(inet_sk((struct sock *)owner)->inet_sport)); 873 if (!mptcp_pm_sport_in_anno_list(owner, sk)) { 874 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX); 875 goto dispose_child; 876 } 877 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX); 878 } 879 880 if (!mptcp_finish_join(child)) 881 goto dispose_child; 882 883 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX); 884 tcp_rsk(req)->drop_req = true; 885 } 886 } 887 888 out: 889 /* dispose of the left over mptcp master, if any */ 890 if (unlikely(new_msk)) 891 mptcp_force_close(new_msk); 892 893 /* check for expected invariant - should never trigger, just help 894 * catching eariler subtle bugs 895 */ 896 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp && 897 (!mptcp_subflow_ctx(child) || 898 !mptcp_subflow_ctx(child)->conn)); 899 return child; 900 901 dispose_child: 902 subflow_drop_ctx(child); 903 tcp_rsk(req)->drop_req = true; 904 inet_csk_prepare_for_destroy_sock(child); 905 tcp_done(child); 906 req->rsk_ops->send_reset(sk, skb); 907 908 /* The last child reference will be released by the caller */ 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; 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 && schedule_work(&msk->work)) 1107 sock_hold((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 struct sock *sk = (struct sock *)msk; 1211 1212 if (likely(ssk->sk_state != TCP_CLOSE)) 1213 return; 1214 1215 if (skb_queue_empty(&ssk->sk_receive_queue) && 1216 !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) { 1217 sock_hold(sk); 1218 if (!schedule_work(&msk->work)) 1219 sock_put(sk); 1220 } 1221 } 1222 1223 static bool subflow_can_fallback(struct mptcp_subflow_context *subflow) 1224 { 1225 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 1226 1227 if (subflow->mp_join) 1228 return false; 1229 else if (READ_ONCE(msk->csum_enabled)) 1230 return !subflow->valid_csum_seen; 1231 else 1232 return !subflow->fully_established; 1233 } 1234 1235 static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk) 1236 { 1237 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1238 unsigned long fail_tout; 1239 1240 /* greceful failure can happen only on the MPC subflow */ 1241 if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first))) 1242 return; 1243 1244 /* since the close timeout take precedence on the fail one, 1245 * no need to start the latter when the first is already set 1246 */ 1247 if (sock_flag((struct sock *)msk, SOCK_DEAD)) 1248 return; 1249 1250 /* we don't need extreme accuracy here, use a zero fail_tout as special 1251 * value meaning no fail timeout at all; 1252 */ 1253 fail_tout = jiffies + TCP_RTO_MAX; 1254 if (!fail_tout) 1255 fail_tout = 1; 1256 WRITE_ONCE(subflow->fail_tout, fail_tout); 1257 tcp_send_ack(ssk); 1258 1259 mptcp_reset_timeout(msk, subflow->fail_tout); 1260 } 1261 1262 static bool subflow_check_data_avail(struct sock *ssk) 1263 { 1264 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1265 enum mapping_status status; 1266 struct mptcp_sock *msk; 1267 struct sk_buff *skb; 1268 1269 if (!skb_peek(&ssk->sk_receive_queue)) 1270 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA); 1271 if (subflow->data_avail) 1272 return true; 1273 1274 msk = mptcp_sk(subflow->conn); 1275 for (;;) { 1276 u64 ack_seq; 1277 u64 old_ack; 1278 1279 status = get_mapping_status(ssk, msk); 1280 trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue)); 1281 if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY || 1282 status == MAPPING_BAD_CSUM)) 1283 goto fallback; 1284 1285 if (status != MAPPING_OK) 1286 goto no_data; 1287 1288 skb = skb_peek(&ssk->sk_receive_queue); 1289 if (WARN_ON_ONCE(!skb)) 1290 goto no_data; 1291 1292 if (unlikely(!READ_ONCE(msk->can_ack))) 1293 goto fallback; 1294 1295 old_ack = READ_ONCE(msk->ack_seq); 1296 ack_seq = mptcp_subflow_get_mapped_dsn(subflow); 1297 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack, 1298 ack_seq); 1299 if (unlikely(before64(ack_seq, old_ack))) { 1300 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq); 1301 continue; 1302 } 1303 1304 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL); 1305 break; 1306 } 1307 return true; 1308 1309 no_data: 1310 subflow_sched_work_if_closed(msk, ssk); 1311 return false; 1312 1313 fallback: 1314 if (!__mptcp_check_fallback(msk)) { 1315 /* RFC 8684 section 3.7. */ 1316 if (status == MAPPING_BAD_CSUM && 1317 (subflow->mp_join || subflow->valid_csum_seen)) { 1318 subflow->send_mp_fail = 1; 1319 1320 if (!READ_ONCE(msk->allow_infinite_fallback)) { 1321 subflow->reset_transient = 0; 1322 subflow->reset_reason = MPTCP_RST_EMIDDLEBOX; 1323 goto reset; 1324 } 1325 mptcp_subflow_fail(msk, ssk); 1326 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL); 1327 return true; 1328 } 1329 1330 if (!subflow_can_fallback(subflow) && subflow->map_data_len) { 1331 /* fatal protocol error, close the socket. 1332 * subflow_error_report() will introduce the appropriate barriers 1333 */ 1334 subflow->reset_transient = 0; 1335 subflow->reset_reason = MPTCP_RST_EMPTCP; 1336 1337 reset: 1338 ssk->sk_err = EBADMSG; 1339 tcp_set_state(ssk, TCP_CLOSE); 1340 while ((skb = skb_peek(&ssk->sk_receive_queue))) 1341 sk_eat_skb(ssk, skb); 1342 tcp_send_active_reset(ssk, GFP_ATOMIC); 1343 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA); 1344 return false; 1345 } 1346 1347 mptcp_do_fallback(ssk); 1348 } 1349 1350 skb = skb_peek(&ssk->sk_receive_queue); 1351 subflow->map_valid = 1; 1352 subflow->map_seq = READ_ONCE(msk->ack_seq); 1353 subflow->map_data_len = skb->len; 1354 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset; 1355 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL); 1356 return true; 1357 } 1358 1359 bool mptcp_subflow_data_available(struct sock *sk) 1360 { 1361 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1362 1363 /* check if current mapping is still valid */ 1364 if (subflow->map_valid && 1365 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) { 1366 subflow->map_valid = 0; 1367 WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA); 1368 1369 pr_debug("Done with mapping: seq=%u data_len=%u", 1370 subflow->map_subflow_seq, 1371 subflow->map_data_len); 1372 } 1373 1374 return subflow_check_data_avail(sk); 1375 } 1376 1377 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy, 1378 * not the ssk one. 1379 * 1380 * In mptcp, rwin is about the mptcp-level connection data. 1381 * 1382 * Data that is still on the ssk rx queue can thus be ignored, 1383 * as far as mptcp peer is concerned that data is still inflight. 1384 * DSS ACK is updated when skb is moved to the mptcp rx queue. 1385 */ 1386 void mptcp_space(const struct sock *ssk, int *space, int *full_space) 1387 { 1388 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1389 const struct sock *sk = subflow->conn; 1390 1391 *space = __mptcp_space(sk); 1392 *full_space = tcp_full_space(sk); 1393 } 1394 1395 void __mptcp_error_report(struct sock *sk) 1396 { 1397 struct mptcp_subflow_context *subflow; 1398 struct mptcp_sock *msk = mptcp_sk(sk); 1399 1400 mptcp_for_each_subflow(msk, subflow) { 1401 struct sock *ssk = mptcp_subflow_tcp_sock(subflow); 1402 int err = sock_error(ssk); 1403 int ssk_state; 1404 1405 if (!err) 1406 continue; 1407 1408 /* only propagate errors on fallen-back sockets or 1409 * on MPC connect 1410 */ 1411 if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk)) 1412 continue; 1413 1414 /* We need to propagate only transition to CLOSE state. 1415 * Orphaned socket will see such state change via 1416 * subflow_sched_work_if_closed() and that path will properly 1417 * destroy the msk as needed. 1418 */ 1419 ssk_state = inet_sk_state_load(ssk); 1420 if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD)) 1421 inet_sk_state_store(sk, ssk_state); 1422 sk->sk_err = -err; 1423 1424 /* This barrier is coupled with smp_rmb() in mptcp_poll() */ 1425 smp_wmb(); 1426 sk_error_report(sk); 1427 break; 1428 } 1429 } 1430 1431 static void subflow_error_report(struct sock *ssk) 1432 { 1433 struct sock *sk = mptcp_subflow_ctx(ssk)->conn; 1434 1435 mptcp_data_lock(sk); 1436 if (!sock_owned_by_user(sk)) 1437 __mptcp_error_report(sk); 1438 else 1439 __set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags); 1440 mptcp_data_unlock(sk); 1441 } 1442 1443 static void subflow_data_ready(struct sock *sk) 1444 { 1445 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1446 u16 state = 1 << inet_sk_state_load(sk); 1447 struct sock *parent = subflow->conn; 1448 struct mptcp_sock *msk; 1449 1450 trace_sk_data_ready(sk); 1451 1452 msk = mptcp_sk(parent); 1453 if (state & TCPF_LISTEN) { 1454 /* MPJ subflow are removed from accept queue before reaching here, 1455 * avoid stray wakeups 1456 */ 1457 if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue)) 1458 return; 1459 1460 parent->sk_data_ready(parent); 1461 return; 1462 } 1463 1464 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && 1465 !subflow->mp_join && !(state & TCPF_CLOSE)); 1466 1467 if (mptcp_subflow_data_available(sk)) 1468 mptcp_data_ready(parent, sk); 1469 else if (unlikely(sk->sk_err)) 1470 subflow_error_report(sk); 1471 } 1472 1473 static void subflow_write_space(struct sock *ssk) 1474 { 1475 struct sock *sk = mptcp_subflow_ctx(ssk)->conn; 1476 1477 mptcp_propagate_sndbuf(sk, ssk); 1478 mptcp_write_space(sk); 1479 } 1480 1481 static const struct inet_connection_sock_af_ops * 1482 subflow_default_af_ops(struct sock *sk) 1483 { 1484 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1485 if (sk->sk_family == AF_INET6) 1486 return &subflow_v6_specific; 1487 #endif 1488 return &subflow_specific; 1489 } 1490 1491 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1492 void mptcpv6_handle_mapped(struct sock *sk, bool mapped) 1493 { 1494 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1495 struct inet_connection_sock *icsk = inet_csk(sk); 1496 const struct inet_connection_sock_af_ops *target; 1497 1498 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk); 1499 1500 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d", 1501 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped); 1502 1503 if (likely(icsk->icsk_af_ops == target)) 1504 return; 1505 1506 subflow->icsk_af_ops = icsk->icsk_af_ops; 1507 icsk->icsk_af_ops = target; 1508 } 1509 #endif 1510 1511 void mptcp_info2sockaddr(const struct mptcp_addr_info *info, 1512 struct sockaddr_storage *addr, 1513 unsigned short family) 1514 { 1515 memset(addr, 0, sizeof(*addr)); 1516 addr->ss_family = family; 1517 if (addr->ss_family == AF_INET) { 1518 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr; 1519 1520 if (info->family == AF_INET) 1521 in_addr->sin_addr = info->addr; 1522 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1523 else if (ipv6_addr_v4mapped(&info->addr6)) 1524 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3]; 1525 #endif 1526 in_addr->sin_port = info->port; 1527 } 1528 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1529 else if (addr->ss_family == AF_INET6) { 1530 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr; 1531 1532 if (info->family == AF_INET) 1533 ipv6_addr_set_v4mapped(info->addr.s_addr, 1534 &in6_addr->sin6_addr); 1535 else 1536 in6_addr->sin6_addr = info->addr6; 1537 in6_addr->sin6_port = info->port; 1538 } 1539 #endif 1540 } 1541 1542 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc, 1543 const struct mptcp_addr_info *remote) 1544 { 1545 struct mptcp_sock *msk = mptcp_sk(sk); 1546 struct mptcp_subflow_context *subflow; 1547 struct sockaddr_storage addr; 1548 int remote_id = remote->id; 1549 int local_id = loc->id; 1550 int err = -ENOTCONN; 1551 struct socket *sf; 1552 struct sock *ssk; 1553 u32 remote_token; 1554 int addrlen; 1555 int ifindex; 1556 u8 flags; 1557 1558 if (!mptcp_is_fully_established(sk)) 1559 goto err_out; 1560 1561 err = mptcp_subflow_create_socket(sk, loc->family, &sf); 1562 if (err) 1563 goto err_out; 1564 1565 ssk = sf->sk; 1566 subflow = mptcp_subflow_ctx(ssk); 1567 do { 1568 get_random_bytes(&subflow->local_nonce, sizeof(u32)); 1569 } while (!subflow->local_nonce); 1570 1571 if (local_id) 1572 subflow_set_local_id(subflow, local_id); 1573 1574 mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id, 1575 &flags, &ifindex); 1576 subflow->remote_key_valid = 1; 1577 subflow->remote_key = msk->remote_key; 1578 subflow->local_key = msk->local_key; 1579 subflow->token = msk->token; 1580 mptcp_info2sockaddr(loc, &addr, ssk->sk_family); 1581 1582 addrlen = sizeof(struct sockaddr_in); 1583 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1584 if (addr.ss_family == AF_INET6) 1585 addrlen = sizeof(struct sockaddr_in6); 1586 #endif 1587 mptcp_sockopt_sync(msk, ssk); 1588 1589 ssk->sk_bound_dev_if = ifindex; 1590 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen); 1591 if (err) 1592 goto failed; 1593 1594 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL); 1595 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk, 1596 remote_token, local_id, remote_id); 1597 subflow->remote_token = remote_token; 1598 subflow->remote_id = remote_id; 1599 subflow->request_join = 1; 1600 subflow->request_bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP); 1601 mptcp_info2sockaddr(remote, &addr, ssk->sk_family); 1602 1603 sock_hold(ssk); 1604 list_add_tail(&subflow->node, &msk->conn_list); 1605 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK); 1606 if (err && err != -EINPROGRESS) 1607 goto failed_unlink; 1608 1609 /* discard the subflow socket */ 1610 mptcp_sock_graft(ssk, sk->sk_socket); 1611 iput(SOCK_INODE(sf)); 1612 WRITE_ONCE(msk->allow_infinite_fallback, false); 1613 return 0; 1614 1615 failed_unlink: 1616 list_del(&subflow->node); 1617 sock_put(mptcp_subflow_tcp_sock(subflow)); 1618 1619 failed: 1620 subflow->disposable = 1; 1621 sock_release(sf); 1622 1623 err_out: 1624 /* we account subflows before the creation, and this failures will not 1625 * be caught by sk_state_change() 1626 */ 1627 mptcp_pm_close_subflow(msk); 1628 return err; 1629 } 1630 1631 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child) 1632 { 1633 #ifdef CONFIG_SOCK_CGROUP_DATA 1634 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data, 1635 *child_skcd = &child->sk_cgrp_data; 1636 1637 /* only the additional subflows created by kworkers have to be modified */ 1638 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) != 1639 cgroup_id(sock_cgroup_ptr(child_skcd))) { 1640 #ifdef CONFIG_MEMCG 1641 struct mem_cgroup *memcg = parent->sk_memcg; 1642 1643 mem_cgroup_sk_free(child); 1644 if (memcg && css_tryget(&memcg->css)) 1645 child->sk_memcg = memcg; 1646 #endif /* CONFIG_MEMCG */ 1647 1648 cgroup_sk_free(child_skcd); 1649 *child_skcd = *parent_skcd; 1650 cgroup_sk_clone(child_skcd); 1651 } 1652 #endif /* CONFIG_SOCK_CGROUP_DATA */ 1653 } 1654 1655 static void mptcp_subflow_ops_override(struct sock *ssk) 1656 { 1657 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1658 if (ssk->sk_prot == &tcpv6_prot) 1659 ssk->sk_prot = &tcpv6_prot_override; 1660 else 1661 #endif 1662 ssk->sk_prot = &tcp_prot_override; 1663 } 1664 1665 static void mptcp_subflow_ops_undo_override(struct sock *ssk) 1666 { 1667 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1668 if (ssk->sk_prot == &tcpv6_prot_override) 1669 ssk->sk_prot = &tcpv6_prot; 1670 else 1671 #endif 1672 ssk->sk_prot = &tcp_prot; 1673 } 1674 1675 int mptcp_subflow_create_socket(struct sock *sk, unsigned short family, 1676 struct socket **new_sock) 1677 { 1678 struct mptcp_subflow_context *subflow; 1679 struct net *net = sock_net(sk); 1680 struct socket *sf; 1681 int err; 1682 1683 /* un-accepted server sockets can reach here - on bad configuration 1684 * bail early to avoid greater trouble later 1685 */ 1686 if (unlikely(!sk->sk_socket)) 1687 return -EINVAL; 1688 1689 err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf); 1690 if (err) 1691 return err; 1692 1693 lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING); 1694 1695 /* the newly created socket has to be in the same cgroup as its parent */ 1696 mptcp_attach_cgroup(sk, sf->sk); 1697 1698 /* kernel sockets do not by default acquire net ref, but TCP timer 1699 * needs it. 1700 * Update ns_tracker to current stack trace and refcounted tracker. 1701 */ 1702 __netns_tracker_free(net, &sf->sk->ns_tracker, false); 1703 sf->sk->sk_net_refcnt = 1; 1704 get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL); 1705 sock_inuse_add(net, 1); 1706 err = tcp_set_ulp(sf->sk, "mptcp"); 1707 release_sock(sf->sk); 1708 1709 if (err) { 1710 sock_release(sf); 1711 return err; 1712 } 1713 1714 /* the newly created socket really belongs to the owning MPTCP master 1715 * socket, even if for additional subflows the allocation is performed 1716 * by a kernel workqueue. Adjust inode references, so that the 1717 * procfs/diag interfaces really show this one belonging to the correct 1718 * user. 1719 */ 1720 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino; 1721 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid; 1722 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid; 1723 1724 subflow = mptcp_subflow_ctx(sf->sk); 1725 pr_debug("subflow=%p", subflow); 1726 1727 *new_sock = sf; 1728 sock_hold(sk); 1729 subflow->conn = sk; 1730 mptcp_subflow_ops_override(sf->sk); 1731 1732 return 0; 1733 } 1734 1735 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk, 1736 gfp_t priority) 1737 { 1738 struct inet_connection_sock *icsk = inet_csk(sk); 1739 struct mptcp_subflow_context *ctx; 1740 1741 ctx = kzalloc(sizeof(*ctx), priority); 1742 if (!ctx) 1743 return NULL; 1744 1745 rcu_assign_pointer(icsk->icsk_ulp_data, ctx); 1746 INIT_LIST_HEAD(&ctx->node); 1747 INIT_LIST_HEAD(&ctx->delegated_node); 1748 1749 pr_debug("subflow=%p", ctx); 1750 1751 ctx->tcp_sock = sk; 1752 1753 return ctx; 1754 } 1755 1756 static void __subflow_state_change(struct sock *sk) 1757 { 1758 struct socket_wq *wq; 1759 1760 rcu_read_lock(); 1761 wq = rcu_dereference(sk->sk_wq); 1762 if (skwq_has_sleeper(wq)) 1763 wake_up_interruptible_all(&wq->wait); 1764 rcu_read_unlock(); 1765 } 1766 1767 static bool subflow_is_done(const struct sock *sk) 1768 { 1769 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE; 1770 } 1771 1772 static void subflow_state_change(struct sock *sk) 1773 { 1774 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1775 struct sock *parent = subflow->conn; 1776 1777 __subflow_state_change(sk); 1778 1779 if (subflow_simultaneous_connect(sk)) { 1780 mptcp_propagate_sndbuf(parent, sk); 1781 mptcp_do_fallback(sk); 1782 mptcp_rcv_space_init(mptcp_sk(parent), sk); 1783 pr_fallback(mptcp_sk(parent)); 1784 subflow->conn_finished = 1; 1785 mptcp_set_connected(parent); 1786 } 1787 1788 /* as recvmsg() does not acquire the subflow socket for ssk selection 1789 * a fin packet carrying a DSS can be unnoticed if we don't trigger 1790 * the data available machinery here. 1791 */ 1792 if (mptcp_subflow_data_available(sk)) 1793 mptcp_data_ready(parent, sk); 1794 else if (unlikely(sk->sk_err)) 1795 subflow_error_report(sk); 1796 1797 subflow_sched_work_if_closed(mptcp_sk(parent), sk); 1798 1799 if (__mptcp_check_fallback(mptcp_sk(parent)) && 1800 !subflow->rx_eof && subflow_is_done(sk)) { 1801 subflow->rx_eof = 1; 1802 mptcp_subflow_eof(parent); 1803 } 1804 } 1805 1806 void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk) 1807 { 1808 struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue; 1809 struct mptcp_sock *msk, *next, *head = NULL; 1810 struct request_sock *req; 1811 1812 /* build a list of all unaccepted mptcp sockets */ 1813 spin_lock_bh(&queue->rskq_lock); 1814 for (req = queue->rskq_accept_head; req; req = req->dl_next) { 1815 struct mptcp_subflow_context *subflow; 1816 struct sock *ssk = req->sk; 1817 struct mptcp_sock *msk; 1818 1819 if (!sk_is_mptcp(ssk)) 1820 continue; 1821 1822 subflow = mptcp_subflow_ctx(ssk); 1823 if (!subflow || !subflow->conn) 1824 continue; 1825 1826 /* skip if already in list */ 1827 msk = mptcp_sk(subflow->conn); 1828 if (msk->dl_next || msk == head) 1829 continue; 1830 1831 msk->dl_next = head; 1832 head = msk; 1833 } 1834 spin_unlock_bh(&queue->rskq_lock); 1835 if (!head) 1836 return; 1837 1838 /* can't acquire the msk socket lock under the subflow one, 1839 * or will cause ABBA deadlock 1840 */ 1841 release_sock(listener_ssk); 1842 1843 for (msk = head; msk; msk = next) { 1844 struct sock *sk = (struct sock *)msk; 1845 bool do_cancel_work; 1846 1847 sock_hold(sk); 1848 lock_sock_nested(sk, SINGLE_DEPTH_NESTING); 1849 next = msk->dl_next; 1850 msk->first = NULL; 1851 msk->dl_next = NULL; 1852 1853 do_cancel_work = __mptcp_close(sk, 0); 1854 release_sock(sk); 1855 if (do_cancel_work) { 1856 /* lockdep will report a false positive ABBA deadlock 1857 * between cancel_work_sync and the listener socket. 1858 * The involved locks belong to different sockets WRT 1859 * the existing AB chain. 1860 * Using a per socket key is problematic as key 1861 * deregistration requires process context and must be 1862 * performed at socket disposal time, in atomic 1863 * context. 1864 * Just tell lockdep to consider the listener socket 1865 * released here. 1866 */ 1867 mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_); 1868 mptcp_cancel_work(sk); 1869 mutex_acquire(&listener_sk->sk_lock.dep_map, 1870 SINGLE_DEPTH_NESTING, 0, _RET_IP_); 1871 } 1872 sock_put(sk); 1873 } 1874 1875 /* we are still under the listener msk socket lock */ 1876 lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING); 1877 } 1878 1879 static int subflow_ulp_init(struct sock *sk) 1880 { 1881 struct inet_connection_sock *icsk = inet_csk(sk); 1882 struct mptcp_subflow_context *ctx; 1883 struct tcp_sock *tp = tcp_sk(sk); 1884 int err = 0; 1885 1886 /* disallow attaching ULP to a socket unless it has been 1887 * created with sock_create_kern() 1888 */ 1889 if (!sk->sk_kern_sock) { 1890 err = -EOPNOTSUPP; 1891 goto out; 1892 } 1893 1894 ctx = subflow_create_ctx(sk, GFP_KERNEL); 1895 if (!ctx) { 1896 err = -ENOMEM; 1897 goto out; 1898 } 1899 1900 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family); 1901 1902 tp->is_mptcp = 1; 1903 ctx->icsk_af_ops = icsk->icsk_af_ops; 1904 icsk->icsk_af_ops = subflow_default_af_ops(sk); 1905 ctx->tcp_state_change = sk->sk_state_change; 1906 ctx->tcp_error_report = sk->sk_error_report; 1907 1908 WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable); 1909 WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space); 1910 1911 sk->sk_data_ready = subflow_data_ready; 1912 sk->sk_write_space = subflow_write_space; 1913 sk->sk_state_change = subflow_state_change; 1914 sk->sk_error_report = subflow_error_report; 1915 out: 1916 return err; 1917 } 1918 1919 static void subflow_ulp_release(struct sock *ssk) 1920 { 1921 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 1922 bool release = true; 1923 struct sock *sk; 1924 1925 if (!ctx) 1926 return; 1927 1928 sk = ctx->conn; 1929 if (sk) { 1930 /* if the msk has been orphaned, keep the ctx 1931 * alive, will be freed by __mptcp_close_ssk(), 1932 * when the subflow is still unaccepted 1933 */ 1934 release = ctx->disposable || list_empty(&ctx->node); 1935 sock_put(sk); 1936 } 1937 1938 mptcp_subflow_ops_undo_override(ssk); 1939 if (release) 1940 kfree_rcu(ctx, rcu); 1941 } 1942 1943 static void subflow_ulp_clone(const struct request_sock *req, 1944 struct sock *newsk, 1945 const gfp_t priority) 1946 { 1947 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 1948 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk); 1949 struct mptcp_subflow_context *new_ctx; 1950 1951 if (!tcp_rsk(req)->is_mptcp || 1952 (!subflow_req->mp_capable && !subflow_req->mp_join)) { 1953 subflow_ulp_fallback(newsk, old_ctx); 1954 return; 1955 } 1956 1957 new_ctx = subflow_create_ctx(newsk, priority); 1958 if (!new_ctx) { 1959 subflow_ulp_fallback(newsk, old_ctx); 1960 return; 1961 } 1962 1963 new_ctx->conn_finished = 1; 1964 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops; 1965 new_ctx->tcp_state_change = old_ctx->tcp_state_change; 1966 new_ctx->tcp_error_report = old_ctx->tcp_error_report; 1967 new_ctx->rel_write_seq = 1; 1968 new_ctx->tcp_sock = newsk; 1969 1970 if (subflow_req->mp_capable) { 1971 /* see comments in subflow_syn_recv_sock(), MPTCP connection 1972 * is fully established only after we receive the remote key 1973 */ 1974 new_ctx->mp_capable = 1; 1975 new_ctx->local_key = subflow_req->local_key; 1976 new_ctx->token = subflow_req->token; 1977 new_ctx->ssn_offset = subflow_req->ssn_offset; 1978 new_ctx->idsn = subflow_req->idsn; 1979 1980 /* this is the first subflow, id is always 0 */ 1981 new_ctx->local_id_valid = 1; 1982 } else if (subflow_req->mp_join) { 1983 new_ctx->ssn_offset = subflow_req->ssn_offset; 1984 new_ctx->mp_join = 1; 1985 new_ctx->fully_established = 1; 1986 new_ctx->remote_key_valid = 1; 1987 new_ctx->backup = subflow_req->backup; 1988 new_ctx->remote_id = subflow_req->remote_id; 1989 new_ctx->token = subflow_req->token; 1990 new_ctx->thmac = subflow_req->thmac; 1991 1992 /* the subflow req id is valid, fetched via subflow_check_req() 1993 * and subflow_token_join_request() 1994 */ 1995 subflow_set_local_id(new_ctx, subflow_req->local_id); 1996 } 1997 } 1998 1999 static void tcp_release_cb_override(struct sock *ssk) 2000 { 2001 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 2002 2003 if (mptcp_subflow_has_delegated_action(subflow)) 2004 mptcp_subflow_process_delegated(ssk); 2005 2006 tcp_release_cb(ssk); 2007 } 2008 2009 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = { 2010 .name = "mptcp", 2011 .owner = THIS_MODULE, 2012 .init = subflow_ulp_init, 2013 .release = subflow_ulp_release, 2014 .clone = subflow_ulp_clone, 2015 }; 2016 2017 static int subflow_ops_init(struct request_sock_ops *subflow_ops) 2018 { 2019 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock); 2020 2021 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name, 2022 subflow_ops->obj_size, 0, 2023 SLAB_ACCOUNT | 2024 SLAB_TYPESAFE_BY_RCU, 2025 NULL); 2026 if (!subflow_ops->slab) 2027 return -ENOMEM; 2028 2029 return 0; 2030 } 2031 2032 void __init mptcp_subflow_init(void) 2033 { 2034 mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops; 2035 mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4"; 2036 mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor; 2037 2038 if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0) 2039 panic("MPTCP: failed to init subflow v4 request sock ops\n"); 2040 2041 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops; 2042 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req; 2043 subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack; 2044 2045 subflow_specific = ipv4_specific; 2046 subflow_specific.conn_request = subflow_v4_conn_request; 2047 subflow_specific.syn_recv_sock = subflow_syn_recv_sock; 2048 subflow_specific.sk_rx_dst_set = subflow_finish_connect; 2049 subflow_specific.rebuild_header = subflow_rebuild_header; 2050 2051 tcp_prot_override = tcp_prot; 2052 tcp_prot_override.release_cb = tcp_release_cb_override; 2053 2054 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 2055 /* In struct mptcp_subflow_request_sock, we assume the TCP request sock 2056 * structures for v4 and v6 have the same size. It should not changed in 2057 * the future but better to make sure to be warned if it is no longer 2058 * the case. 2059 */ 2060 BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock)); 2061 2062 mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops; 2063 mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6"; 2064 mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor; 2065 2066 if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0) 2067 panic("MPTCP: failed to init subflow v6 request sock ops\n"); 2068 2069 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops; 2070 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req; 2071 subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack; 2072 2073 subflow_v6_specific = ipv6_specific; 2074 subflow_v6_specific.conn_request = subflow_v6_conn_request; 2075 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock; 2076 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect; 2077 subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header; 2078 2079 subflow_v6m_specific = subflow_v6_specific; 2080 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit; 2081 subflow_v6m_specific.send_check = ipv4_specific.send_check; 2082 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len; 2083 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced; 2084 subflow_v6m_specific.net_frag_header_len = 0; 2085 subflow_v6m_specific.rebuild_header = subflow_rebuild_header; 2086 2087 tcpv6_prot_override = tcpv6_prot; 2088 tcpv6_prot_override.release_cb = tcp_release_cb_override; 2089 #endif 2090 2091 mptcp_diag_subflow_init(&subflow_ulp_ops); 2092 2093 if (tcp_register_ulp(&subflow_ulp_ops) != 0) 2094 panic("MPTCP: failed to register subflows to ULP\n"); 2095 } 2096