1 // SPDX-License-Identifier: GPL-2.0 2 /* Multipath TCP 3 * 4 * Copyright (c) 2017 - 2019, Intel Corporation. 5 */ 6 7 #define pr_fmt(fmt) "MPTCP: " fmt 8 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/netdevice.h> 12 #include <crypto/algapi.h> 13 #include <crypto/sha2.h> 14 #include <net/sock.h> 15 #include <net/inet_common.h> 16 #include <net/inet_hashtables.h> 17 #include <net/protocol.h> 18 #include <net/tcp.h> 19 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 20 #include <net/ip6_route.h> 21 #include <net/transp_v6.h> 22 #endif 23 #include <net/mptcp.h> 24 #include <uapi/linux/mptcp.h> 25 #include "protocol.h" 26 #include "mib.h" 27 28 static void mptcp_subflow_ops_undo_override(struct sock *ssk); 29 30 static void SUBFLOW_REQ_INC_STATS(struct request_sock *req, 31 enum linux_mptcp_mib_field field) 32 { 33 MPTCP_INC_STATS(sock_net(req_to_sk(req)), field); 34 } 35 36 static void subflow_req_destructor(struct request_sock *req) 37 { 38 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 39 40 pr_debug("subflow_req=%p", subflow_req); 41 42 if (subflow_req->msk) 43 sock_put((struct sock *)subflow_req->msk); 44 45 mptcp_token_destroy_request(req); 46 tcp_request_sock_ops.destructor(req); 47 } 48 49 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2, 50 void *hmac) 51 { 52 u8 msg[8]; 53 54 put_unaligned_be32(nonce1, &msg[0]); 55 put_unaligned_be32(nonce2, &msg[4]); 56 57 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac); 58 } 59 60 static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk) 61 { 62 return mptcp_is_fully_established((void *)msk) && 63 READ_ONCE(msk->pm.accept_subflow); 64 } 65 66 /* validate received token and create truncated hmac and nonce for SYN-ACK */ 67 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req, 68 const struct sk_buff *skb) 69 { 70 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 71 u8 hmac[SHA256_DIGEST_SIZE]; 72 struct mptcp_sock *msk; 73 int local_id; 74 75 msk = mptcp_token_get_sock(subflow_req->token); 76 if (!msk) { 77 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN); 78 return NULL; 79 } 80 81 local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req); 82 if (local_id < 0) { 83 sock_put((struct sock *)msk); 84 return NULL; 85 } 86 subflow_req->local_id = local_id; 87 88 get_random_bytes(&subflow_req->local_nonce, sizeof(u32)); 89 90 subflow_generate_hmac(msk->local_key, msk->remote_key, 91 subflow_req->local_nonce, 92 subflow_req->remote_nonce, hmac); 93 94 subflow_req->thmac = get_unaligned_be64(hmac); 95 return msk; 96 } 97 98 static int __subflow_init_req(struct request_sock *req, const struct sock *sk_listener) 99 { 100 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 101 102 subflow_req->mp_capable = 0; 103 subflow_req->mp_join = 0; 104 subflow_req->msk = NULL; 105 mptcp_token_init_request(req); 106 107 #ifdef CONFIG_TCP_MD5SIG 108 /* no MPTCP if MD5SIG is enabled on this socket or we may run out of 109 * TCP option space. 110 */ 111 if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) 112 return -EINVAL; 113 #endif 114 115 return 0; 116 } 117 118 /* Init mptcp request socket. 119 * 120 * Returns an error code if a JOIN has failed and a TCP reset 121 * should be sent. 122 */ 123 static int subflow_init_req(struct request_sock *req, 124 const struct sock *sk_listener, 125 struct sk_buff *skb) 126 { 127 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 128 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 129 struct mptcp_options_received mp_opt; 130 int ret; 131 132 pr_debug("subflow_req=%p, listener=%p", subflow_req, listener); 133 134 ret = __subflow_init_req(req, sk_listener); 135 if (ret) 136 return 0; 137 138 mptcp_get_options(skb, &mp_opt); 139 140 if (mp_opt.mp_capable) { 141 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE); 142 143 if (mp_opt.mp_join) 144 return 0; 145 } else if (mp_opt.mp_join) { 146 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX); 147 } 148 149 if (mp_opt.mp_capable && listener->request_mptcp) { 150 int err, retries = 4; 151 152 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 153 again: 154 do { 155 get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key)); 156 } while (subflow_req->local_key == 0); 157 158 if (unlikely(req->syncookie)) { 159 mptcp_crypto_key_sha(subflow_req->local_key, 160 &subflow_req->token, 161 &subflow_req->idsn); 162 if (mptcp_token_exists(subflow_req->token)) { 163 if (retries-- > 0) 164 goto again; 165 } else { 166 subflow_req->mp_capable = 1; 167 } 168 return 0; 169 } 170 171 err = mptcp_token_new_request(req); 172 if (err == 0) 173 subflow_req->mp_capable = 1; 174 else if (retries-- > 0) 175 goto again; 176 177 } else if (mp_opt.mp_join && listener->request_mptcp) { 178 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq; 179 subflow_req->mp_join = 1; 180 subflow_req->backup = mp_opt.backup; 181 subflow_req->remote_id = mp_opt.join_id; 182 subflow_req->token = mp_opt.token; 183 subflow_req->remote_nonce = mp_opt.nonce; 184 subflow_req->msk = subflow_token_join_request(req, skb); 185 186 /* Can't fall back to TCP in this case. */ 187 if (!subflow_req->msk) 188 return -EPERM; 189 190 if (unlikely(req->syncookie)) { 191 if (mptcp_can_accept_new_subflow(subflow_req->msk)) 192 subflow_init_req_cookie_join_save(subflow_req, skb); 193 } 194 195 pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token, 196 subflow_req->remote_nonce, subflow_req->msk); 197 } 198 199 return 0; 200 } 201 202 int mptcp_subflow_init_cookie_req(struct request_sock *req, 203 const struct sock *sk_listener, 204 struct sk_buff *skb) 205 { 206 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener); 207 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 208 struct mptcp_options_received mp_opt; 209 int err; 210 211 err = __subflow_init_req(req, sk_listener); 212 if (err) 213 return err; 214 215 mptcp_get_options(skb, &mp_opt); 216 217 if (mp_opt.mp_capable && mp_opt.mp_join) 218 return -EINVAL; 219 220 if (mp_opt.mp_capable && listener->request_mptcp) { 221 if (mp_opt.sndr_key == 0) 222 return -EINVAL; 223 224 subflow_req->local_key = mp_opt.rcvr_key; 225 err = mptcp_token_new_request(req); 226 if (err) 227 return err; 228 229 subflow_req->mp_capable = 1; 230 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 231 } else if (mp_opt.mp_join && listener->request_mptcp) { 232 if (!mptcp_token_join_cookie_init_state(subflow_req, skb)) 233 return -EINVAL; 234 235 if (mptcp_can_accept_new_subflow(subflow_req->msk)) 236 subflow_req->mp_join = 1; 237 238 subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; 239 } 240 241 return 0; 242 } 243 EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req); 244 245 static struct dst_entry *subflow_v4_route_req(const struct sock *sk, 246 struct sk_buff *skb, 247 struct flowi *fl, 248 struct request_sock *req) 249 { 250 struct dst_entry *dst; 251 int err; 252 253 tcp_rsk(req)->is_mptcp = 1; 254 255 dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req); 256 if (!dst) 257 return NULL; 258 259 err = subflow_init_req(req, sk, skb); 260 if (err == 0) 261 return dst; 262 263 dst_release(dst); 264 if (!req->syncookie) 265 tcp_request_sock_ops.send_reset(sk, skb); 266 return NULL; 267 } 268 269 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 270 static struct dst_entry *subflow_v6_route_req(const struct sock *sk, 271 struct sk_buff *skb, 272 struct flowi *fl, 273 struct request_sock *req) 274 { 275 struct dst_entry *dst; 276 int err; 277 278 tcp_rsk(req)->is_mptcp = 1; 279 280 dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req); 281 if (!dst) 282 return NULL; 283 284 err = subflow_init_req(req, sk, skb); 285 if (err == 0) 286 return dst; 287 288 dst_release(dst); 289 if (!req->syncookie) 290 tcp6_request_sock_ops.send_reset(sk, skb); 291 return NULL; 292 } 293 #endif 294 295 /* validate received truncated hmac and create hmac for third ACK */ 296 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow) 297 { 298 u8 hmac[SHA256_DIGEST_SIZE]; 299 u64 thmac; 300 301 subflow_generate_hmac(subflow->remote_key, subflow->local_key, 302 subflow->remote_nonce, subflow->local_nonce, 303 hmac); 304 305 thmac = get_unaligned_be64(hmac); 306 pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n", 307 subflow, subflow->token, 308 (unsigned long long)thmac, 309 (unsigned long long)subflow->thmac); 310 311 return thmac == subflow->thmac; 312 } 313 314 void mptcp_subflow_reset(struct sock *ssk) 315 { 316 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 317 struct sock *sk = subflow->conn; 318 319 /* must hold: tcp_done() could drop last reference on parent */ 320 sock_hold(sk); 321 322 tcp_set_state(ssk, TCP_CLOSE); 323 tcp_send_active_reset(ssk, GFP_ATOMIC); 324 tcp_done(ssk); 325 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) && 326 schedule_work(&mptcp_sk(sk)->work)) 327 return; /* worker will put sk for us */ 328 329 sock_put(sk); 330 } 331 332 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 333 { 334 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 335 struct mptcp_options_received mp_opt; 336 struct sock *parent = subflow->conn; 337 338 subflow->icsk_af_ops->sk_rx_dst_set(sk, skb); 339 340 if (inet_sk_state_load(parent) == TCP_SYN_SENT) { 341 inet_sk_state_store(parent, TCP_ESTABLISHED); 342 parent->sk_state_change(parent); 343 } 344 345 /* be sure no special action on any packet other than syn-ack */ 346 if (subflow->conn_finished) 347 return; 348 349 mptcp_propagate_sndbuf(parent, sk); 350 subflow->rel_write_seq = 1; 351 subflow->conn_finished = 1; 352 subflow->ssn_offset = TCP_SKB_CB(skb)->seq; 353 pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset); 354 355 mptcp_get_options(skb, &mp_opt); 356 if (subflow->request_mptcp) { 357 if (!mp_opt.mp_capable) { 358 MPTCP_INC_STATS(sock_net(sk), 359 MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); 360 mptcp_do_fallback(sk); 361 pr_fallback(mptcp_sk(subflow->conn)); 362 goto fallback; 363 } 364 365 subflow->mp_capable = 1; 366 subflow->can_ack = 1; 367 subflow->remote_key = mp_opt.sndr_key; 368 pr_debug("subflow=%p, remote_key=%llu", subflow, 369 subflow->remote_key); 370 mptcp_finish_connect(sk); 371 } else if (subflow->request_join) { 372 u8 hmac[SHA256_DIGEST_SIZE]; 373 374 if (!mp_opt.mp_join) 375 goto do_reset; 376 377 subflow->thmac = mp_opt.thmac; 378 subflow->remote_nonce = mp_opt.nonce; 379 pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow, 380 subflow->thmac, subflow->remote_nonce); 381 382 if (!subflow_thmac_valid(subflow)) { 383 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC); 384 goto do_reset; 385 } 386 387 subflow_generate_hmac(subflow->local_key, subflow->remote_key, 388 subflow->local_nonce, 389 subflow->remote_nonce, 390 hmac); 391 memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN); 392 393 if (!mptcp_finish_join(sk)) 394 goto do_reset; 395 396 subflow->mp_join = 1; 397 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX); 398 } else if (mptcp_check_fallback(sk)) { 399 fallback: 400 mptcp_rcv_space_init(mptcp_sk(parent), sk); 401 } 402 return; 403 404 do_reset: 405 mptcp_subflow_reset(sk); 406 } 407 408 struct request_sock_ops mptcp_subflow_request_sock_ops; 409 EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops); 410 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops; 411 412 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb) 413 { 414 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 415 416 pr_debug("subflow=%p", subflow); 417 418 /* Never answer to SYNs sent to broadcast or multicast */ 419 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 420 goto drop; 421 422 return tcp_conn_request(&mptcp_subflow_request_sock_ops, 423 &subflow_request_sock_ipv4_ops, 424 sk, skb); 425 drop: 426 tcp_listendrop(sk); 427 return 0; 428 } 429 430 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 431 static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops; 432 static struct inet_connection_sock_af_ops subflow_v6_specific; 433 static struct inet_connection_sock_af_ops subflow_v6m_specific; 434 static struct proto tcpv6_prot_override; 435 436 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb) 437 { 438 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 439 440 pr_debug("subflow=%p", subflow); 441 442 if (skb->protocol == htons(ETH_P_IP)) 443 return subflow_v4_conn_request(sk, skb); 444 445 if (!ipv6_unicast_destination(skb)) 446 goto drop; 447 448 return tcp_conn_request(&mptcp_subflow_request_sock_ops, 449 &subflow_request_sock_ipv6_ops, sk, skb); 450 451 drop: 452 tcp_listendrop(sk); 453 return 0; /* don't send reset */ 454 } 455 #endif 456 457 /* validate hmac received in third ACK */ 458 static bool subflow_hmac_valid(const struct request_sock *req, 459 const struct mptcp_options_received *mp_opt) 460 { 461 const struct mptcp_subflow_request_sock *subflow_req; 462 u8 hmac[SHA256_DIGEST_SIZE]; 463 struct mptcp_sock *msk; 464 465 subflow_req = mptcp_subflow_rsk(req); 466 msk = subflow_req->msk; 467 if (!msk) 468 return false; 469 470 subflow_generate_hmac(msk->remote_key, msk->local_key, 471 subflow_req->remote_nonce, 472 subflow_req->local_nonce, hmac); 473 474 return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN); 475 } 476 477 static void mptcp_sock_destruct(struct sock *sk) 478 { 479 /* if new mptcp socket isn't accepted, it is free'd 480 * from the tcp listener sockets request queue, linked 481 * from req->sk. The tcp socket is released. 482 * This calls the ULP release function which will 483 * also remove the mptcp socket, via 484 * sock_put(ctx->conn). 485 * 486 * Problem is that the mptcp socket will be in 487 * ESTABLISHED state and will not have the SOCK_DEAD flag. 488 * Both result in warnings from inet_sock_destruct. 489 */ 490 491 if (sk->sk_state == TCP_ESTABLISHED) { 492 sk->sk_state = TCP_CLOSE; 493 WARN_ON_ONCE(sk->sk_socket); 494 sock_orphan(sk); 495 } 496 497 mptcp_destroy_common(mptcp_sk(sk)); 498 inet_sock_destruct(sk); 499 } 500 501 static void mptcp_force_close(struct sock *sk) 502 { 503 inet_sk_state_store(sk, TCP_CLOSE); 504 sk_common_release(sk); 505 } 506 507 static void subflow_ulp_fallback(struct sock *sk, 508 struct mptcp_subflow_context *old_ctx) 509 { 510 struct inet_connection_sock *icsk = inet_csk(sk); 511 512 mptcp_subflow_tcp_fallback(sk, old_ctx); 513 icsk->icsk_ulp_ops = NULL; 514 rcu_assign_pointer(icsk->icsk_ulp_data, NULL); 515 tcp_sk(sk)->is_mptcp = 0; 516 517 mptcp_subflow_ops_undo_override(sk); 518 } 519 520 static void subflow_drop_ctx(struct sock *ssk) 521 { 522 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 523 524 if (!ctx) 525 return; 526 527 subflow_ulp_fallback(ssk, ctx); 528 if (ctx->conn) 529 sock_put(ctx->conn); 530 531 kfree_rcu(ctx, rcu); 532 } 533 534 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow, 535 struct mptcp_options_received *mp_opt) 536 { 537 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 538 539 subflow->remote_key = mp_opt->sndr_key; 540 subflow->fully_established = 1; 541 subflow->can_ack = 1; 542 WRITE_ONCE(msk->fully_established, true); 543 } 544 545 static struct sock *subflow_syn_recv_sock(const struct sock *sk, 546 struct sk_buff *skb, 547 struct request_sock *req, 548 struct dst_entry *dst, 549 struct request_sock *req_unhash, 550 bool *own_req) 551 { 552 struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk); 553 struct mptcp_subflow_request_sock *subflow_req; 554 struct mptcp_options_received mp_opt; 555 bool fallback, fallback_is_fatal; 556 struct sock *new_msk = NULL; 557 struct sock *child; 558 559 pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn); 560 561 /* After child creation we must look for 'mp_capable' even when options 562 * are not parsed 563 */ 564 mp_opt.mp_capable = 0; 565 566 /* hopefully temporary handling for MP_JOIN+syncookie */ 567 subflow_req = mptcp_subflow_rsk(req); 568 fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join; 569 fallback = !tcp_rsk(req)->is_mptcp; 570 if (fallback) 571 goto create_child; 572 573 /* if the sk is MP_CAPABLE, we try to fetch the client key */ 574 if (subflow_req->mp_capable) { 575 if (TCP_SKB_CB(skb)->seq != subflow_req->ssn_offset + 1) { 576 /* here we can receive and accept an in-window, 577 * out-of-order pkt, which will not carry the MP_CAPABLE 578 * opt even on mptcp enabled paths 579 */ 580 goto create_msk; 581 } 582 583 mptcp_get_options(skb, &mp_opt); 584 if (!mp_opt.mp_capable) { 585 fallback = true; 586 goto create_child; 587 } 588 589 create_msk: 590 new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req); 591 if (!new_msk) 592 fallback = true; 593 } else if (subflow_req->mp_join) { 594 mptcp_get_options(skb, &mp_opt); 595 if (!mp_opt.mp_join || !subflow_hmac_valid(req, &mp_opt) || 596 !mptcp_can_accept_new_subflow(subflow_req->msk)) { 597 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC); 598 fallback = true; 599 } 600 } 601 602 create_child: 603 child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, 604 req_unhash, own_req); 605 606 if (child && *own_req) { 607 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child); 608 609 tcp_rsk(req)->drop_req = false; 610 611 /* we need to fallback on ctx allocation failure and on pre-reqs 612 * checking above. In the latter scenario we additionally need 613 * to reset the context to non MPTCP status. 614 */ 615 if (!ctx || fallback) { 616 if (fallback_is_fatal) 617 goto dispose_child; 618 619 subflow_drop_ctx(child); 620 goto out; 621 } 622 623 if (ctx->mp_capable) { 624 /* this can't race with mptcp_close(), as the msk is 625 * not yet exposted to user-space 626 */ 627 inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED); 628 629 /* record the newly created socket as the first msk 630 * subflow, but don't link it yet into conn_list 631 */ 632 WRITE_ONCE(mptcp_sk(new_msk)->first, child); 633 634 /* new mpc subflow takes ownership of the newly 635 * created mptcp socket 636 */ 637 new_msk->sk_destruct = mptcp_sock_destruct; 638 mptcp_pm_new_connection(mptcp_sk(new_msk), 1); 639 mptcp_token_accept(subflow_req, mptcp_sk(new_msk)); 640 ctx->conn = new_msk; 641 new_msk = NULL; 642 643 /* with OoO packets we can reach here without ingress 644 * mpc option 645 */ 646 if (mp_opt.mp_capable) 647 mptcp_subflow_fully_established(ctx, &mp_opt); 648 } else if (ctx->mp_join) { 649 struct mptcp_sock *owner; 650 651 owner = subflow_req->msk; 652 if (!owner) 653 goto dispose_child; 654 655 /* move the msk reference ownership to the subflow */ 656 subflow_req->msk = NULL; 657 ctx->conn = (struct sock *)owner; 658 if (!mptcp_finish_join(child)) 659 goto dispose_child; 660 661 SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX); 662 tcp_rsk(req)->drop_req = true; 663 } 664 } 665 666 out: 667 /* dispose of the left over mptcp master, if any */ 668 if (unlikely(new_msk)) 669 mptcp_force_close(new_msk); 670 671 /* check for expected invariant - should never trigger, just help 672 * catching eariler subtle bugs 673 */ 674 WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp && 675 (!mptcp_subflow_ctx(child) || 676 !mptcp_subflow_ctx(child)->conn)); 677 return child; 678 679 dispose_child: 680 subflow_drop_ctx(child); 681 tcp_rsk(req)->drop_req = true; 682 inet_csk_prepare_for_destroy_sock(child); 683 tcp_done(child); 684 req->rsk_ops->send_reset(sk, skb); 685 686 /* The last child reference will be released by the caller */ 687 return child; 688 } 689 690 static struct inet_connection_sock_af_ops subflow_specific; 691 static struct proto tcp_prot_override; 692 693 enum mapping_status { 694 MAPPING_OK, 695 MAPPING_INVALID, 696 MAPPING_EMPTY, 697 MAPPING_DATA_FIN, 698 MAPPING_DUMMY 699 }; 700 701 static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq) 702 { 703 if ((u32)seq == (u32)old_seq) 704 return old_seq; 705 706 /* Assume map covers data not mapped yet. */ 707 return seq | ((old_seq + old_data_len + 1) & GENMASK_ULL(63, 32)); 708 } 709 710 static void warn_bad_map(struct mptcp_subflow_context *subflow, u32 ssn) 711 { 712 WARN_ONCE(1, "Bad mapping: ssn=%d map_seq=%d map_data_len=%d", 713 ssn, subflow->map_subflow_seq, subflow->map_data_len); 714 } 715 716 static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb) 717 { 718 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 719 unsigned int skb_consumed; 720 721 skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq; 722 if (WARN_ON_ONCE(skb_consumed >= skb->len)) 723 return true; 724 725 return skb->len - skb_consumed <= subflow->map_data_len - 726 mptcp_subflow_get_map_offset(subflow); 727 } 728 729 static bool validate_mapping(struct sock *ssk, struct sk_buff *skb) 730 { 731 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 732 u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset; 733 734 if (unlikely(before(ssn, subflow->map_subflow_seq))) { 735 /* Mapping covers data later in the subflow stream, 736 * currently unsupported. 737 */ 738 warn_bad_map(subflow, ssn); 739 return false; 740 } 741 if (unlikely(!before(ssn, subflow->map_subflow_seq + 742 subflow->map_data_len))) { 743 /* Mapping does covers past subflow data, invalid */ 744 warn_bad_map(subflow, ssn + skb->len); 745 return false; 746 } 747 return true; 748 } 749 750 static enum mapping_status get_mapping_status(struct sock *ssk, 751 struct mptcp_sock *msk) 752 { 753 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 754 struct mptcp_ext *mpext; 755 struct sk_buff *skb; 756 u16 data_len; 757 u64 map_seq; 758 759 skb = skb_peek(&ssk->sk_receive_queue); 760 if (!skb) 761 return MAPPING_EMPTY; 762 763 if (mptcp_check_fallback(ssk)) 764 return MAPPING_DUMMY; 765 766 mpext = mptcp_get_ext(skb); 767 if (!mpext || !mpext->use_map) { 768 if (!subflow->map_valid && !skb->len) { 769 /* the TCP stack deliver 0 len FIN pkt to the receive 770 * queue, that is the only 0len pkts ever expected here, 771 * and we can admit no mapping only for 0 len pkts 772 */ 773 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 774 WARN_ONCE(1, "0len seq %d:%d flags %x", 775 TCP_SKB_CB(skb)->seq, 776 TCP_SKB_CB(skb)->end_seq, 777 TCP_SKB_CB(skb)->tcp_flags); 778 sk_eat_skb(ssk, skb); 779 return MAPPING_EMPTY; 780 } 781 782 if (!subflow->map_valid) 783 return MAPPING_INVALID; 784 785 goto validate_seq; 786 } 787 788 pr_debug("seq=%llu is64=%d ssn=%u data_len=%u data_fin=%d", 789 mpext->data_seq, mpext->dsn64, mpext->subflow_seq, 790 mpext->data_len, mpext->data_fin); 791 792 data_len = mpext->data_len; 793 if (data_len == 0) { 794 pr_err("Infinite mapping not handled"); 795 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX); 796 return MAPPING_INVALID; 797 } 798 799 if (mpext->data_fin == 1) { 800 if (data_len == 1) { 801 bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq, 802 mpext->dsn64); 803 pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq); 804 if (subflow->map_valid) { 805 /* A DATA_FIN might arrive in a DSS 806 * option before the previous mapping 807 * has been fully consumed. Continue 808 * handling the existing mapping. 809 */ 810 skb_ext_del(skb, SKB_EXT_MPTCP); 811 return MAPPING_OK; 812 } else { 813 if (updated && schedule_work(&msk->work)) 814 sock_hold((struct sock *)msk); 815 816 return MAPPING_DATA_FIN; 817 } 818 } else { 819 u64 data_fin_seq = mpext->data_seq + data_len - 1; 820 821 /* If mpext->data_seq is a 32-bit value, data_fin_seq 822 * must also be limited to 32 bits. 823 */ 824 if (!mpext->dsn64) 825 data_fin_seq &= GENMASK_ULL(31, 0); 826 827 mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64); 828 pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d", 829 data_fin_seq, mpext->dsn64); 830 } 831 832 /* Adjust for DATA_FIN using 1 byte of sequence space */ 833 data_len--; 834 } 835 836 if (!mpext->dsn64) { 837 map_seq = expand_seq(subflow->map_seq, subflow->map_data_len, 838 mpext->data_seq); 839 pr_debug("expanded seq=%llu", subflow->map_seq); 840 } else { 841 map_seq = mpext->data_seq; 842 } 843 WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64); 844 845 if (subflow->map_valid) { 846 /* Allow replacing only with an identical map */ 847 if (subflow->map_seq == map_seq && 848 subflow->map_subflow_seq == mpext->subflow_seq && 849 subflow->map_data_len == data_len) { 850 skb_ext_del(skb, SKB_EXT_MPTCP); 851 return MAPPING_OK; 852 } 853 854 /* If this skb data are fully covered by the current mapping, 855 * the new map would need caching, which is not supported 856 */ 857 if (skb_is_fully_mapped(ssk, skb)) { 858 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH); 859 return MAPPING_INVALID; 860 } 861 862 /* will validate the next map after consuming the current one */ 863 return MAPPING_OK; 864 } 865 866 subflow->map_seq = map_seq; 867 subflow->map_subflow_seq = mpext->subflow_seq; 868 subflow->map_data_len = data_len; 869 subflow->map_valid = 1; 870 subflow->mpc_map = mpext->mpc_map; 871 pr_debug("new map seq=%llu subflow_seq=%u data_len=%u", 872 subflow->map_seq, subflow->map_subflow_seq, 873 subflow->map_data_len); 874 875 validate_seq: 876 /* we revalidate valid mapping on new skb, because we must ensure 877 * the current skb is completely covered by the available mapping 878 */ 879 if (!validate_mapping(ssk, skb)) 880 return MAPPING_INVALID; 881 882 skb_ext_del(skb, SKB_EXT_MPTCP); 883 return MAPPING_OK; 884 } 885 886 static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb, 887 u64 limit) 888 { 889 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 890 bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN; 891 u32 incr; 892 893 incr = limit >= skb->len ? skb->len + fin : limit; 894 895 pr_debug("discarding=%d len=%d seq=%d", incr, skb->len, 896 subflow->map_subflow_seq); 897 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA); 898 tcp_sk(ssk)->copied_seq += incr; 899 if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq)) 900 sk_eat_skb(ssk, skb); 901 if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) 902 subflow->map_valid = 0; 903 } 904 905 static bool subflow_check_data_avail(struct sock *ssk) 906 { 907 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 908 enum mapping_status status; 909 struct mptcp_sock *msk; 910 struct sk_buff *skb; 911 912 pr_debug("msk=%p ssk=%p data_avail=%d skb=%p", subflow->conn, ssk, 913 subflow->data_avail, skb_peek(&ssk->sk_receive_queue)); 914 if (!skb_peek(&ssk->sk_receive_queue)) 915 subflow->data_avail = 0; 916 if (subflow->data_avail) 917 return true; 918 919 msk = mptcp_sk(subflow->conn); 920 for (;;) { 921 u64 ack_seq; 922 u64 old_ack; 923 924 status = get_mapping_status(ssk, msk); 925 pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status); 926 if (status == MAPPING_INVALID) { 927 ssk->sk_err = EBADMSG; 928 goto fatal; 929 } 930 if (status == MAPPING_DUMMY) { 931 __mptcp_do_fallback(msk); 932 skb = skb_peek(&ssk->sk_receive_queue); 933 subflow->map_valid = 1; 934 subflow->map_seq = READ_ONCE(msk->ack_seq); 935 subflow->map_data_len = skb->len; 936 subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - 937 subflow->ssn_offset; 938 subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL; 939 return true; 940 } 941 942 if (status != MAPPING_OK) 943 return false; 944 945 skb = skb_peek(&ssk->sk_receive_queue); 946 if (WARN_ON_ONCE(!skb)) 947 return false; 948 949 /* if msk lacks the remote key, this subflow must provide an 950 * MP_CAPABLE-based mapping 951 */ 952 if (unlikely(!READ_ONCE(msk->can_ack))) { 953 if (!subflow->mpc_map) { 954 ssk->sk_err = EBADMSG; 955 goto fatal; 956 } 957 WRITE_ONCE(msk->remote_key, subflow->remote_key); 958 WRITE_ONCE(msk->ack_seq, subflow->map_seq); 959 WRITE_ONCE(msk->can_ack, true); 960 } 961 962 old_ack = READ_ONCE(msk->ack_seq); 963 ack_seq = mptcp_subflow_get_mapped_dsn(subflow); 964 pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack, 965 ack_seq); 966 if (ack_seq == old_ack) { 967 subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL; 968 break; 969 } else if (after64(ack_seq, old_ack)) { 970 subflow->data_avail = MPTCP_SUBFLOW_OOO_DATA; 971 break; 972 } 973 974 /* only accept in-sequence mapping. Old values are spurious 975 * retransmission 976 */ 977 mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq); 978 } 979 return true; 980 981 fatal: 982 /* fatal protocol error, close the socket */ 983 /* This barrier is coupled with smp_rmb() in tcp_poll() */ 984 smp_wmb(); 985 ssk->sk_error_report(ssk); 986 tcp_set_state(ssk, TCP_CLOSE); 987 tcp_send_active_reset(ssk, GFP_ATOMIC); 988 subflow->data_avail = 0; 989 return false; 990 } 991 992 bool mptcp_subflow_data_available(struct sock *sk) 993 { 994 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 995 996 /* check if current mapping is still valid */ 997 if (subflow->map_valid && 998 mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) { 999 subflow->map_valid = 0; 1000 subflow->data_avail = 0; 1001 1002 pr_debug("Done with mapping: seq=%u data_len=%u", 1003 subflow->map_subflow_seq, 1004 subflow->map_data_len); 1005 } 1006 1007 return subflow_check_data_avail(sk); 1008 } 1009 1010 /* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy, 1011 * not the ssk one. 1012 * 1013 * In mptcp, rwin is about the mptcp-level connection data. 1014 * 1015 * Data that is still on the ssk rx queue can thus be ignored, 1016 * as far as mptcp peer is concerened that data is still inflight. 1017 * DSS ACK is updated when skb is moved to the mptcp rx queue. 1018 */ 1019 void mptcp_space(const struct sock *ssk, int *space, int *full_space) 1020 { 1021 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1022 const struct sock *sk = subflow->conn; 1023 1024 *space = __mptcp_space(sk); 1025 *full_space = tcp_full_space(sk); 1026 } 1027 1028 static void subflow_data_ready(struct sock *sk) 1029 { 1030 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1031 u16 state = 1 << inet_sk_state_load(sk); 1032 struct sock *parent = subflow->conn; 1033 struct mptcp_sock *msk; 1034 1035 msk = mptcp_sk(parent); 1036 if (state & TCPF_LISTEN) { 1037 set_bit(MPTCP_DATA_READY, &msk->flags); 1038 parent->sk_data_ready(parent); 1039 return; 1040 } 1041 1042 WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && 1043 !subflow->mp_join && !(state & TCPF_CLOSE)); 1044 1045 if (mptcp_subflow_data_available(sk)) 1046 mptcp_data_ready(parent, sk); 1047 } 1048 1049 static void subflow_write_space(struct sock *ssk) 1050 { 1051 struct sock *sk = mptcp_subflow_ctx(ssk)->conn; 1052 1053 mptcp_propagate_sndbuf(sk, ssk); 1054 mptcp_write_space(sk); 1055 } 1056 1057 static struct inet_connection_sock_af_ops * 1058 subflow_default_af_ops(struct sock *sk) 1059 { 1060 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1061 if (sk->sk_family == AF_INET6) 1062 return &subflow_v6_specific; 1063 #endif 1064 return &subflow_specific; 1065 } 1066 1067 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1068 void mptcpv6_handle_mapped(struct sock *sk, bool mapped) 1069 { 1070 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1071 struct inet_connection_sock *icsk = inet_csk(sk); 1072 struct inet_connection_sock_af_ops *target; 1073 1074 target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk); 1075 1076 pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d", 1077 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped); 1078 1079 if (likely(icsk->icsk_af_ops == target)) 1080 return; 1081 1082 subflow->icsk_af_ops = icsk->icsk_af_ops; 1083 icsk->icsk_af_ops = target; 1084 } 1085 #endif 1086 1087 static void mptcp_info2sockaddr(const struct mptcp_addr_info *info, 1088 struct sockaddr_storage *addr, 1089 unsigned short family) 1090 { 1091 memset(addr, 0, sizeof(*addr)); 1092 addr->ss_family = family; 1093 if (addr->ss_family == AF_INET) { 1094 struct sockaddr_in *in_addr = (struct sockaddr_in *)addr; 1095 1096 if (info->family == AF_INET) 1097 in_addr->sin_addr = info->addr; 1098 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1099 else if (ipv6_addr_v4mapped(&info->addr6)) 1100 in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3]; 1101 #endif 1102 in_addr->sin_port = info->port; 1103 } 1104 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1105 else if (addr->ss_family == AF_INET6) { 1106 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr; 1107 1108 if (info->family == AF_INET) 1109 ipv6_addr_set_v4mapped(info->addr.s_addr, 1110 &in6_addr->sin6_addr); 1111 else 1112 in6_addr->sin6_addr = info->addr6; 1113 in6_addr->sin6_port = info->port; 1114 } 1115 #endif 1116 } 1117 1118 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc, 1119 const struct mptcp_addr_info *remote) 1120 { 1121 struct mptcp_sock *msk = mptcp_sk(sk); 1122 struct mptcp_subflow_context *subflow; 1123 struct sockaddr_storage addr; 1124 int remote_id = remote->id; 1125 int local_id = loc->id; 1126 struct socket *sf; 1127 struct sock *ssk; 1128 u32 remote_token; 1129 int addrlen; 1130 int err; 1131 1132 if (!mptcp_is_fully_established(sk)) 1133 return -ENOTCONN; 1134 1135 err = mptcp_subflow_create_socket(sk, &sf); 1136 if (err) 1137 return err; 1138 1139 ssk = sf->sk; 1140 subflow = mptcp_subflow_ctx(ssk); 1141 do { 1142 get_random_bytes(&subflow->local_nonce, sizeof(u32)); 1143 } while (!subflow->local_nonce); 1144 1145 if (!local_id) { 1146 err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk); 1147 if (err < 0) 1148 goto failed; 1149 1150 local_id = err; 1151 } 1152 1153 subflow->remote_key = msk->remote_key; 1154 subflow->local_key = msk->local_key; 1155 subflow->token = msk->token; 1156 mptcp_info2sockaddr(loc, &addr, ssk->sk_family); 1157 1158 addrlen = sizeof(struct sockaddr_in); 1159 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1160 if (addr.ss_family == AF_INET6) 1161 addrlen = sizeof(struct sockaddr_in6); 1162 #endif 1163 ssk->sk_bound_dev_if = loc->ifindex; 1164 err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen); 1165 if (err) 1166 goto failed; 1167 1168 mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL); 1169 pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d", msk, 1170 remote_token, local_id, remote_id); 1171 subflow->remote_token = remote_token; 1172 subflow->local_id = local_id; 1173 subflow->remote_id = remote_id; 1174 subflow->request_join = 1; 1175 subflow->request_bkup = !!(loc->flags & MPTCP_PM_ADDR_FLAG_BACKUP); 1176 mptcp_info2sockaddr(remote, &addr, ssk->sk_family); 1177 1178 mptcp_add_pending_subflow(msk, subflow); 1179 err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK); 1180 if (err && err != -EINPROGRESS) 1181 goto failed_unlink; 1182 1183 /* discard the subflow socket */ 1184 mptcp_sock_graft(ssk, sk->sk_socket); 1185 iput(SOCK_INODE(sf)); 1186 return err; 1187 1188 failed_unlink: 1189 spin_lock_bh(&msk->join_list_lock); 1190 list_del(&subflow->node); 1191 spin_unlock_bh(&msk->join_list_lock); 1192 1193 failed: 1194 subflow->disposable = 1; 1195 sock_release(sf); 1196 return err; 1197 } 1198 1199 static void mptcp_attach_cgroup(struct sock *parent, struct sock *child) 1200 { 1201 #ifdef CONFIG_SOCK_CGROUP_DATA 1202 struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data, 1203 *child_skcd = &child->sk_cgrp_data; 1204 1205 /* only the additional subflows created by kworkers have to be modified */ 1206 if (cgroup_id(sock_cgroup_ptr(parent_skcd)) != 1207 cgroup_id(sock_cgroup_ptr(child_skcd))) { 1208 #ifdef CONFIG_MEMCG 1209 struct mem_cgroup *memcg = parent->sk_memcg; 1210 1211 mem_cgroup_sk_free(child); 1212 if (memcg && css_tryget(&memcg->css)) 1213 child->sk_memcg = memcg; 1214 #endif /* CONFIG_MEMCG */ 1215 1216 cgroup_sk_free(child_skcd); 1217 *child_skcd = *parent_skcd; 1218 cgroup_sk_clone(child_skcd); 1219 } 1220 #endif /* CONFIG_SOCK_CGROUP_DATA */ 1221 } 1222 1223 static void mptcp_subflow_ops_override(struct sock *ssk) 1224 { 1225 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1226 if (ssk->sk_prot == &tcpv6_prot) 1227 ssk->sk_prot = &tcpv6_prot_override; 1228 else 1229 #endif 1230 ssk->sk_prot = &tcp_prot_override; 1231 } 1232 1233 static void mptcp_subflow_ops_undo_override(struct sock *ssk) 1234 { 1235 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1236 if (ssk->sk_prot == &tcpv6_prot_override) 1237 ssk->sk_prot = &tcpv6_prot; 1238 else 1239 #endif 1240 ssk->sk_prot = &tcp_prot; 1241 } 1242 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock) 1243 { 1244 struct mptcp_subflow_context *subflow; 1245 struct net *net = sock_net(sk); 1246 struct socket *sf; 1247 int err; 1248 1249 /* un-accepted server sockets can reach here - on bad configuration 1250 * bail early to avoid greater trouble later 1251 */ 1252 if (unlikely(!sk->sk_socket)) 1253 return -EINVAL; 1254 1255 err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP, 1256 &sf); 1257 if (err) 1258 return err; 1259 1260 lock_sock(sf->sk); 1261 1262 /* the newly created socket has to be in the same cgroup as its parent */ 1263 mptcp_attach_cgroup(sk, sf->sk); 1264 1265 /* kernel sockets do not by default acquire net ref, but TCP timer 1266 * needs it. 1267 */ 1268 sf->sk->sk_net_refcnt = 1; 1269 get_net(net); 1270 #ifdef CONFIG_PROC_FS 1271 this_cpu_add(*net->core.sock_inuse, 1); 1272 #endif 1273 err = tcp_set_ulp(sf->sk, "mptcp"); 1274 release_sock(sf->sk); 1275 1276 if (err) { 1277 sock_release(sf); 1278 return err; 1279 } 1280 1281 /* the newly created socket really belongs to the owning MPTCP master 1282 * socket, even if for additional subflows the allocation is performed 1283 * by a kernel workqueue. Adjust inode references, so that the 1284 * procfs/diag interaces really show this one belonging to the correct 1285 * user. 1286 */ 1287 SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino; 1288 SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid; 1289 SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid; 1290 1291 subflow = mptcp_subflow_ctx(sf->sk); 1292 pr_debug("subflow=%p", subflow); 1293 1294 *new_sock = sf; 1295 sock_hold(sk); 1296 subflow->conn = sk; 1297 mptcp_subflow_ops_override(sf->sk); 1298 1299 return 0; 1300 } 1301 1302 static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk, 1303 gfp_t priority) 1304 { 1305 struct inet_connection_sock *icsk = inet_csk(sk); 1306 struct mptcp_subflow_context *ctx; 1307 1308 ctx = kzalloc(sizeof(*ctx), priority); 1309 if (!ctx) 1310 return NULL; 1311 1312 rcu_assign_pointer(icsk->icsk_ulp_data, ctx); 1313 INIT_LIST_HEAD(&ctx->node); 1314 INIT_LIST_HEAD(&ctx->delegated_node); 1315 1316 pr_debug("subflow=%p", ctx); 1317 1318 ctx->tcp_sock = sk; 1319 1320 return ctx; 1321 } 1322 1323 static void __subflow_state_change(struct sock *sk) 1324 { 1325 struct socket_wq *wq; 1326 1327 rcu_read_lock(); 1328 wq = rcu_dereference(sk->sk_wq); 1329 if (skwq_has_sleeper(wq)) 1330 wake_up_interruptible_all(&wq->wait); 1331 rcu_read_unlock(); 1332 } 1333 1334 static bool subflow_is_done(const struct sock *sk) 1335 { 1336 return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE; 1337 } 1338 1339 static void subflow_state_change(struct sock *sk) 1340 { 1341 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1342 struct sock *parent = subflow->conn; 1343 1344 __subflow_state_change(sk); 1345 1346 if (subflow_simultaneous_connect(sk)) { 1347 mptcp_propagate_sndbuf(parent, sk); 1348 mptcp_do_fallback(sk); 1349 mptcp_rcv_space_init(mptcp_sk(parent), sk); 1350 pr_fallback(mptcp_sk(parent)); 1351 subflow->conn_finished = 1; 1352 if (inet_sk_state_load(parent) == TCP_SYN_SENT) { 1353 inet_sk_state_store(parent, TCP_ESTABLISHED); 1354 parent->sk_state_change(parent); 1355 } 1356 } 1357 1358 /* as recvmsg() does not acquire the subflow socket for ssk selection 1359 * a fin packet carrying a DSS can be unnoticed if we don't trigger 1360 * the data available machinery here. 1361 */ 1362 if (mptcp_subflow_data_available(sk)) 1363 mptcp_data_ready(parent, sk); 1364 1365 if (__mptcp_check_fallback(mptcp_sk(parent)) && 1366 !subflow->rx_eof && subflow_is_done(sk)) { 1367 subflow->rx_eof = 1; 1368 mptcp_subflow_eof(parent); 1369 } 1370 } 1371 1372 static int subflow_ulp_init(struct sock *sk) 1373 { 1374 struct inet_connection_sock *icsk = inet_csk(sk); 1375 struct mptcp_subflow_context *ctx; 1376 struct tcp_sock *tp = tcp_sk(sk); 1377 int err = 0; 1378 1379 /* disallow attaching ULP to a socket unless it has been 1380 * created with sock_create_kern() 1381 */ 1382 if (!sk->sk_kern_sock) { 1383 err = -EOPNOTSUPP; 1384 goto out; 1385 } 1386 1387 ctx = subflow_create_ctx(sk, GFP_KERNEL); 1388 if (!ctx) { 1389 err = -ENOMEM; 1390 goto out; 1391 } 1392 1393 pr_debug("subflow=%p, family=%d", ctx, sk->sk_family); 1394 1395 tp->is_mptcp = 1; 1396 ctx->icsk_af_ops = icsk->icsk_af_ops; 1397 icsk->icsk_af_ops = subflow_default_af_ops(sk); 1398 ctx->tcp_data_ready = sk->sk_data_ready; 1399 ctx->tcp_state_change = sk->sk_state_change; 1400 ctx->tcp_write_space = sk->sk_write_space; 1401 sk->sk_data_ready = subflow_data_ready; 1402 sk->sk_write_space = subflow_write_space; 1403 sk->sk_state_change = subflow_state_change; 1404 out: 1405 return err; 1406 } 1407 1408 static void subflow_ulp_release(struct sock *ssk) 1409 { 1410 struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk); 1411 bool release = true; 1412 struct sock *sk; 1413 1414 if (!ctx) 1415 return; 1416 1417 sk = ctx->conn; 1418 if (sk) { 1419 /* if the msk has been orphaned, keep the ctx 1420 * alive, will be freed by __mptcp_close_ssk(), 1421 * when the subflow is still unaccepted 1422 */ 1423 release = ctx->disposable || list_empty(&ctx->node); 1424 sock_put(sk); 1425 } 1426 1427 mptcp_subflow_ops_undo_override(ssk); 1428 if (release) 1429 kfree_rcu(ctx, rcu); 1430 } 1431 1432 static void subflow_ulp_clone(const struct request_sock *req, 1433 struct sock *newsk, 1434 const gfp_t priority) 1435 { 1436 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 1437 struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk); 1438 struct mptcp_subflow_context *new_ctx; 1439 1440 if (!tcp_rsk(req)->is_mptcp || 1441 (!subflow_req->mp_capable && !subflow_req->mp_join)) { 1442 subflow_ulp_fallback(newsk, old_ctx); 1443 return; 1444 } 1445 1446 new_ctx = subflow_create_ctx(newsk, priority); 1447 if (!new_ctx) { 1448 subflow_ulp_fallback(newsk, old_ctx); 1449 return; 1450 } 1451 1452 new_ctx->conn_finished = 1; 1453 new_ctx->icsk_af_ops = old_ctx->icsk_af_ops; 1454 new_ctx->tcp_data_ready = old_ctx->tcp_data_ready; 1455 new_ctx->tcp_state_change = old_ctx->tcp_state_change; 1456 new_ctx->tcp_write_space = old_ctx->tcp_write_space; 1457 new_ctx->rel_write_seq = 1; 1458 new_ctx->tcp_sock = newsk; 1459 1460 if (subflow_req->mp_capable) { 1461 /* see comments in subflow_syn_recv_sock(), MPTCP connection 1462 * is fully established only after we receive the remote key 1463 */ 1464 new_ctx->mp_capable = 1; 1465 new_ctx->local_key = subflow_req->local_key; 1466 new_ctx->token = subflow_req->token; 1467 new_ctx->ssn_offset = subflow_req->ssn_offset; 1468 new_ctx->idsn = subflow_req->idsn; 1469 } else if (subflow_req->mp_join) { 1470 new_ctx->ssn_offset = subflow_req->ssn_offset; 1471 new_ctx->mp_join = 1; 1472 new_ctx->fully_established = 1; 1473 new_ctx->backup = subflow_req->backup; 1474 new_ctx->local_id = subflow_req->local_id; 1475 new_ctx->remote_id = subflow_req->remote_id; 1476 new_ctx->token = subflow_req->token; 1477 new_ctx->thmac = subflow_req->thmac; 1478 } 1479 } 1480 1481 static void tcp_release_cb_override(struct sock *ssk) 1482 { 1483 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1484 1485 if (mptcp_subflow_has_delegated_action(subflow)) 1486 mptcp_subflow_process_delegated(ssk); 1487 1488 tcp_release_cb(ssk); 1489 } 1490 1491 static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = { 1492 .name = "mptcp", 1493 .owner = THIS_MODULE, 1494 .init = subflow_ulp_init, 1495 .release = subflow_ulp_release, 1496 .clone = subflow_ulp_clone, 1497 }; 1498 1499 static int subflow_ops_init(struct request_sock_ops *subflow_ops) 1500 { 1501 subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock); 1502 subflow_ops->slab_name = "request_sock_subflow"; 1503 1504 subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name, 1505 subflow_ops->obj_size, 0, 1506 SLAB_ACCOUNT | 1507 SLAB_TYPESAFE_BY_RCU, 1508 NULL); 1509 if (!subflow_ops->slab) 1510 return -ENOMEM; 1511 1512 subflow_ops->destructor = subflow_req_destructor; 1513 1514 return 0; 1515 } 1516 1517 void __init mptcp_subflow_init(void) 1518 { 1519 mptcp_subflow_request_sock_ops = tcp_request_sock_ops; 1520 if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0) 1521 panic("MPTCP: failed to init subflow request sock ops\n"); 1522 1523 subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops; 1524 subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req; 1525 1526 subflow_specific = ipv4_specific; 1527 subflow_specific.conn_request = subflow_v4_conn_request; 1528 subflow_specific.syn_recv_sock = subflow_syn_recv_sock; 1529 subflow_specific.sk_rx_dst_set = subflow_finish_connect; 1530 1531 tcp_prot_override = tcp_prot; 1532 tcp_prot_override.release_cb = tcp_release_cb_override; 1533 1534 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1535 subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops; 1536 subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req; 1537 1538 subflow_v6_specific = ipv6_specific; 1539 subflow_v6_specific.conn_request = subflow_v6_conn_request; 1540 subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock; 1541 subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect; 1542 1543 subflow_v6m_specific = subflow_v6_specific; 1544 subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit; 1545 subflow_v6m_specific.send_check = ipv4_specific.send_check; 1546 subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len; 1547 subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced; 1548 subflow_v6m_specific.net_frag_header_len = 0; 1549 1550 tcpv6_prot_override = tcpv6_prot; 1551 tcpv6_prot_override.release_cb = tcp_release_cb_override; 1552 #endif 1553 1554 mptcp_diag_subflow_init(&subflow_ulp_ops); 1555 1556 if (tcp_register_ulp(&subflow_ulp_ops) != 0) 1557 panic("MPTCP: failed to register subflows to ULP\n"); 1558 } 1559