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 <crypto/sha2.h> 11 #include <net/tcp.h> 12 #include <net/mptcp.h> 13 #include "protocol.h" 14 #include "mib.h" 15 16 #include <trace/events/mptcp.h> 17 18 static bool mptcp_cap_flag_sha256(u8 flags) 19 { 20 return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256; 21 } 22 23 static void mptcp_parse_option(const struct sk_buff *skb, 24 const unsigned char *ptr, int opsize, 25 struct mptcp_options_received *mp_opt) 26 { 27 u8 subtype = *ptr >> 4; 28 int expected_opsize; 29 u16 subopt; 30 u8 version; 31 u8 flags; 32 u8 i; 33 34 switch (subtype) { 35 case MPTCPOPT_MP_CAPABLE: 36 /* strict size checking */ 37 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 38 if (skb->len > tcp_hdr(skb)->doff << 2) 39 expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA; 40 else 41 expected_opsize = TCPOLEN_MPTCP_MPC_ACK; 42 subopt = OPTION_MPTCP_MPC_ACK; 43 } else { 44 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK) { 45 expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK; 46 subopt = OPTION_MPTCP_MPC_SYNACK; 47 } else { 48 expected_opsize = TCPOLEN_MPTCP_MPC_SYN; 49 subopt = OPTION_MPTCP_MPC_SYN; 50 } 51 } 52 53 /* Cfr RFC 8684 Section 3.3.0: 54 * If a checksum is present but its use had 55 * not been negotiated in the MP_CAPABLE handshake, the receiver MUST 56 * close the subflow with a RST, as it is not behaving as negotiated. 57 * If a checksum is not present when its use has been negotiated, the 58 * receiver MUST close the subflow with a RST, as it is considered 59 * broken 60 * We parse even option with mismatching csum presence, so that 61 * later in subflow_data_ready we can trigger the reset. 62 */ 63 if (opsize != expected_opsize && 64 (expected_opsize != TCPOLEN_MPTCP_MPC_ACK_DATA || 65 opsize != TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM)) 66 break; 67 68 /* try to be gentle vs future versions on the initial syn */ 69 version = *ptr++ & MPTCP_VERSION_MASK; 70 if (opsize != TCPOLEN_MPTCP_MPC_SYN) { 71 if (version != MPTCP_SUPPORTED_VERSION) 72 break; 73 } else if (version < MPTCP_SUPPORTED_VERSION) { 74 break; 75 } 76 77 flags = *ptr++; 78 if (!mptcp_cap_flag_sha256(flags) || 79 (flags & MPTCP_CAP_EXTENSIBILITY)) 80 break; 81 82 /* RFC 6824, Section 3.1: 83 * "For the Checksum Required bit (labeled "A"), if either 84 * host requires the use of checksums, checksums MUST be used. 85 * In other words, the only way for checksums not to be used 86 * is if both hosts in their SYNs set A=0." 87 */ 88 if (flags & MPTCP_CAP_CHECKSUM_REQD) 89 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 90 91 mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0); 92 93 mp_opt->suboptions |= subopt; 94 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) { 95 mp_opt->sndr_key = get_unaligned_be64(ptr); 96 ptr += 8; 97 } 98 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) { 99 mp_opt->rcvr_key = get_unaligned_be64(ptr); 100 ptr += 8; 101 } 102 if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) { 103 /* Section 3.1.: 104 * "the data parameters in a MP_CAPABLE are semantically 105 * equivalent to those in a DSS option and can be used 106 * interchangeably." 107 */ 108 mp_opt->suboptions |= OPTION_MPTCP_DSS; 109 mp_opt->use_map = 1; 110 mp_opt->mpc_map = 1; 111 mp_opt->data_len = get_unaligned_be16(ptr); 112 ptr += 2; 113 } 114 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) { 115 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 116 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 117 ptr += 2; 118 } 119 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u", 120 version, flags, opsize, mp_opt->sndr_key, 121 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum); 122 break; 123 124 case MPTCPOPT_MP_JOIN: 125 mp_opt->suboptions |= OPTIONS_MPTCP_MPJ; 126 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) { 127 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 128 mp_opt->join_id = *ptr++; 129 mp_opt->token = get_unaligned_be32(ptr); 130 ptr += 4; 131 mp_opt->nonce = get_unaligned_be32(ptr); 132 ptr += 4; 133 pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u", 134 mp_opt->backup, mp_opt->join_id, 135 mp_opt->token, mp_opt->nonce); 136 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) { 137 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 138 mp_opt->join_id = *ptr++; 139 mp_opt->thmac = get_unaligned_be64(ptr); 140 ptr += 8; 141 mp_opt->nonce = get_unaligned_be32(ptr); 142 ptr += 4; 143 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u", 144 mp_opt->backup, mp_opt->join_id, 145 mp_opt->thmac, mp_opt->nonce); 146 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) { 147 ptr += 2; 148 memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN); 149 pr_debug("MP_JOIN hmac"); 150 } else { 151 mp_opt->suboptions &= ~OPTIONS_MPTCP_MPJ; 152 } 153 break; 154 155 case MPTCPOPT_DSS: 156 pr_debug("DSS"); 157 ptr++; 158 159 /* we must clear 'mpc_map' be able to detect MP_CAPABLE 160 * map vs DSS map in mptcp_incoming_options(), and reconstruct 161 * map info accordingly 162 */ 163 mp_opt->mpc_map = 0; 164 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK; 165 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0; 166 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0; 167 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0; 168 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0; 169 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK); 170 171 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d", 172 mp_opt->data_fin, mp_opt->dsn64, 173 mp_opt->use_map, mp_opt->ack64, 174 mp_opt->use_ack); 175 176 expected_opsize = TCPOLEN_MPTCP_DSS_BASE; 177 178 if (mp_opt->use_ack) { 179 if (mp_opt->ack64) 180 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64; 181 else 182 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32; 183 } 184 185 if (mp_opt->use_map) { 186 if (mp_opt->dsn64) 187 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64; 188 else 189 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32; 190 } 191 192 /* Always parse any csum presence combination, we will enforce 193 * RFC 8684 Section 3.3.0 checks later in subflow_data_ready 194 */ 195 if (opsize != expected_opsize && 196 opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) 197 break; 198 199 mp_opt->suboptions |= OPTION_MPTCP_DSS; 200 if (mp_opt->use_ack) { 201 if (mp_opt->ack64) { 202 mp_opt->data_ack = get_unaligned_be64(ptr); 203 ptr += 8; 204 } else { 205 mp_opt->data_ack = get_unaligned_be32(ptr); 206 ptr += 4; 207 } 208 209 pr_debug("data_ack=%llu", mp_opt->data_ack); 210 } 211 212 if (mp_opt->use_map) { 213 if (mp_opt->dsn64) { 214 mp_opt->data_seq = get_unaligned_be64(ptr); 215 ptr += 8; 216 } else { 217 mp_opt->data_seq = get_unaligned_be32(ptr); 218 ptr += 4; 219 } 220 221 mp_opt->subflow_seq = get_unaligned_be32(ptr); 222 ptr += 4; 223 224 mp_opt->data_len = get_unaligned_be16(ptr); 225 ptr += 2; 226 227 if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { 228 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 229 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 230 ptr += 2; 231 } 232 233 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u", 234 mp_opt->data_seq, mp_opt->subflow_seq, 235 mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD), 236 mp_opt->csum); 237 } 238 239 break; 240 241 case MPTCPOPT_ADD_ADDR: 242 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO; 243 if (!mp_opt->echo) { 244 if (opsize == TCPOLEN_MPTCP_ADD_ADDR || 245 opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT) 246 mp_opt->addr.family = AF_INET; 247 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 248 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 || 249 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT) 250 mp_opt->addr.family = AF_INET6; 251 #endif 252 else 253 break; 254 } else { 255 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE || 256 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) 257 mp_opt->addr.family = AF_INET; 258 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 259 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE || 260 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) 261 mp_opt->addr.family = AF_INET6; 262 #endif 263 else 264 break; 265 } 266 267 mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR; 268 mp_opt->addr.id = *ptr++; 269 mp_opt->addr.port = 0; 270 mp_opt->ahmac = 0; 271 if (mp_opt->addr.family == AF_INET) { 272 memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4); 273 ptr += 4; 274 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT || 275 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) { 276 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 277 ptr += 2; 278 } 279 } 280 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 281 else { 282 memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16); 283 ptr += 16; 284 if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT || 285 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) { 286 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 287 ptr += 2; 288 } 289 } 290 #endif 291 if (!mp_opt->echo) { 292 mp_opt->ahmac = get_unaligned_be64(ptr); 293 ptr += 8; 294 } 295 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d", 296 (mp_opt->addr.family == AF_INET6) ? "6" : "", 297 mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port)); 298 break; 299 300 case MPTCPOPT_RM_ADDR: 301 if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 || 302 opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX) 303 break; 304 305 ptr++; 306 307 mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR; 308 mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE; 309 for (i = 0; i < mp_opt->rm_list.nr; i++) 310 mp_opt->rm_list.ids[i] = *ptr++; 311 pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr); 312 break; 313 314 case MPTCPOPT_MP_PRIO: 315 if (opsize != TCPOLEN_MPTCP_PRIO) 316 break; 317 318 mp_opt->suboptions |= OPTION_MPTCP_PRIO; 319 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP; 320 pr_debug("MP_PRIO: prio=%d", mp_opt->backup); 321 break; 322 323 case MPTCPOPT_MP_FASTCLOSE: 324 if (opsize != TCPOLEN_MPTCP_FASTCLOSE) 325 break; 326 327 ptr += 2; 328 mp_opt->rcvr_key = get_unaligned_be64(ptr); 329 ptr += 8; 330 mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE; 331 pr_debug("MP_FASTCLOSE: recv_key=%llu", mp_opt->rcvr_key); 332 break; 333 334 case MPTCPOPT_RST: 335 if (opsize != TCPOLEN_MPTCP_RST) 336 break; 337 338 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) 339 break; 340 341 mp_opt->suboptions |= OPTION_MPTCP_RST; 342 flags = *ptr++; 343 mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT; 344 mp_opt->reset_reason = *ptr; 345 pr_debug("MP_RST: transient=%u reason=%u", 346 mp_opt->reset_transient, mp_opt->reset_reason); 347 break; 348 349 case MPTCPOPT_MP_FAIL: 350 if (opsize != TCPOLEN_MPTCP_FAIL) 351 break; 352 353 ptr += 2; 354 mp_opt->suboptions |= OPTION_MPTCP_FAIL; 355 mp_opt->fail_seq = get_unaligned_be64(ptr); 356 pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq); 357 break; 358 359 default: 360 break; 361 } 362 } 363 364 void mptcp_get_options(const struct sk_buff *skb, 365 struct mptcp_options_received *mp_opt) 366 { 367 const struct tcphdr *th = tcp_hdr(skb); 368 const unsigned char *ptr; 369 int length; 370 371 /* initialize option status */ 372 mp_opt->suboptions = 0; 373 374 length = (th->doff * 4) - sizeof(struct tcphdr); 375 ptr = (const unsigned char *)(th + 1); 376 377 while (length > 0) { 378 int opcode = *ptr++; 379 int opsize; 380 381 switch (opcode) { 382 case TCPOPT_EOL: 383 return; 384 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ 385 length--; 386 continue; 387 default: 388 if (length < 2) 389 return; 390 opsize = *ptr++; 391 if (opsize < 2) /* "silly options" */ 392 return; 393 if (opsize > length) 394 return; /* don't parse partial options */ 395 if (opcode == TCPOPT_MPTCP) 396 mptcp_parse_option(skb, ptr, opsize, mp_opt); 397 ptr += opsize - 2; 398 length -= opsize; 399 } 400 } 401 } 402 403 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb, 404 unsigned int *size, struct mptcp_out_options *opts) 405 { 406 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 407 408 /* we will use snd_isn to detect first pkt [re]transmission 409 * in mptcp_established_options_mp() 410 */ 411 subflow->snd_isn = TCP_SKB_CB(skb)->end_seq; 412 if (subflow->request_mptcp) { 413 opts->suboptions = OPTION_MPTCP_MPC_SYN; 414 opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk)); 415 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 416 *size = TCPOLEN_MPTCP_MPC_SYN; 417 return true; 418 } else if (subflow->request_join) { 419 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token, 420 subflow->local_nonce); 421 opts->suboptions = OPTION_MPTCP_MPJ_SYN; 422 opts->join_id = subflow->local_id; 423 opts->token = subflow->remote_token; 424 opts->nonce = subflow->local_nonce; 425 opts->backup = subflow->request_bkup; 426 *size = TCPOLEN_MPTCP_MPJ_SYN; 427 return true; 428 } 429 return false; 430 } 431 432 static void clear_3rdack_retransmission(struct sock *sk) 433 { 434 struct inet_connection_sock *icsk = inet_csk(sk); 435 436 sk_stop_timer(sk, &icsk->icsk_delack_timer); 437 icsk->icsk_ack.timeout = 0; 438 icsk->icsk_ack.ato = 0; 439 icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER); 440 } 441 442 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, 443 bool snd_data_fin_enable, 444 unsigned int *size, 445 struct mptcp_out_options *opts) 446 { 447 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 448 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 449 struct mptcp_ext *mpext; 450 unsigned int data_len; 451 u8 len; 452 453 /* When skb is not available, we better over-estimate the emitted 454 * options len. A full DSS option (28 bytes) is longer than 455 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so 456 * tell the caller to defer the estimate to 457 * mptcp_established_options_dss(), which will reserve enough space. 458 */ 459 if (!skb) 460 return false; 461 462 /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */ 463 if (subflow->fully_established || snd_data_fin_enable || 464 subflow->snd_isn != TCP_SKB_CB(skb)->seq || 465 sk->sk_state != TCP_ESTABLISHED) 466 return false; 467 468 if (subflow->mp_capable) { 469 mpext = mptcp_get_ext(skb); 470 data_len = mpext ? mpext->data_len : 0; 471 472 /* we will check ops->data_len in mptcp_write_options() to 473 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and 474 * TCPOLEN_MPTCP_MPC_ACK 475 */ 476 opts->data_len = data_len; 477 opts->suboptions = OPTION_MPTCP_MPC_ACK; 478 opts->sndr_key = subflow->local_key; 479 opts->rcvr_key = subflow->remote_key; 480 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 481 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 482 483 /* Section 3.1. 484 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK 485 * packets that start the first subflow of an MPTCP connection, 486 * as well as the first packet that carries data 487 */ 488 if (data_len > 0) { 489 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 490 if (opts->csum_reqd) { 491 /* we need to propagate more info to csum the pseudo hdr */ 492 opts->data_seq = mpext->data_seq; 493 opts->subflow_seq = mpext->subflow_seq; 494 opts->csum = mpext->csum; 495 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 496 } 497 *size = ALIGN(len, 4); 498 } else { 499 *size = TCPOLEN_MPTCP_MPC_ACK; 500 } 501 502 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d", 503 subflow, subflow->local_key, subflow->remote_key, 504 data_len); 505 506 return true; 507 } else if (subflow->mp_join) { 508 opts->suboptions = OPTION_MPTCP_MPJ_ACK; 509 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN); 510 *size = TCPOLEN_MPTCP_MPJ_ACK; 511 pr_debug("subflow=%p", subflow); 512 513 /* we can use the full delegate action helper only from BH context 514 * If we are in process context - sk is flushing the backlog at 515 * socket lock release time - just set the appropriate flag, will 516 * be handled by the release callback 517 */ 518 if (sock_owned_by_user(sk)) 519 set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status); 520 else 521 mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK); 522 return true; 523 } 524 return false; 525 } 526 527 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow, 528 struct sk_buff *skb, struct mptcp_ext *ext) 529 { 530 /* The write_seq value has already been incremented, so the actual 531 * sequence number for the DATA_FIN is one less. 532 */ 533 u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1; 534 535 if (!ext->use_map || !skb->len) { 536 /* RFC6824 requires a DSS mapping with specific values 537 * if DATA_FIN is set but no data payload is mapped 538 */ 539 ext->data_fin = 1; 540 ext->use_map = 1; 541 ext->dsn64 = 1; 542 ext->data_seq = data_fin_tx_seq; 543 ext->subflow_seq = 0; 544 ext->data_len = 1; 545 } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) { 546 /* If there's an existing DSS mapping and it is the 547 * final mapping, DATA_FIN consumes 1 additional byte of 548 * mapping space. 549 */ 550 ext->data_fin = 1; 551 ext->data_len++; 552 } 553 } 554 555 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, 556 bool snd_data_fin_enable, 557 unsigned int *size, 558 struct mptcp_out_options *opts) 559 { 560 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 561 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 562 unsigned int dss_size = 0; 563 struct mptcp_ext *mpext; 564 unsigned int ack_size; 565 bool ret = false; 566 u64 ack_seq; 567 568 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 569 mpext = skb ? mptcp_get_ext(skb) : NULL; 570 571 if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) { 572 unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64; 573 574 if (mpext) { 575 if (opts->csum_reqd) 576 map_size += TCPOLEN_MPTCP_DSS_CHECKSUM; 577 578 opts->ext_copy = *mpext; 579 } 580 581 dss_size = map_size; 582 if (skb && snd_data_fin_enable) 583 mptcp_write_data_fin(subflow, skb, &opts->ext_copy); 584 opts->suboptions = OPTION_MPTCP_DSS; 585 ret = true; 586 } 587 588 /* passive sockets msk will set the 'can_ack' after accept(), even 589 * if the first subflow may have the already the remote key handy 590 */ 591 opts->ext_copy.use_ack = 0; 592 if (!READ_ONCE(msk->can_ack)) { 593 *size = ALIGN(dss_size, 4); 594 return ret; 595 } 596 597 ack_seq = READ_ONCE(msk->ack_seq); 598 if (READ_ONCE(msk->use_64bit_ack)) { 599 ack_size = TCPOLEN_MPTCP_DSS_ACK64; 600 opts->ext_copy.data_ack = ack_seq; 601 opts->ext_copy.ack64 = 1; 602 } else { 603 ack_size = TCPOLEN_MPTCP_DSS_ACK32; 604 opts->ext_copy.data_ack32 = (uint32_t)ack_seq; 605 opts->ext_copy.ack64 = 0; 606 } 607 opts->ext_copy.use_ack = 1; 608 opts->suboptions = OPTION_MPTCP_DSS; 609 WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk)); 610 611 /* Add kind/length/subtype/flag overhead if mapping is not populated */ 612 if (dss_size == 0) 613 ack_size += TCPOLEN_MPTCP_DSS_BASE; 614 615 dss_size += ack_size; 616 617 *size = ALIGN(dss_size, 4); 618 return true; 619 } 620 621 static u64 add_addr_generate_hmac(u64 key1, u64 key2, 622 struct mptcp_addr_info *addr) 623 { 624 u16 port = ntohs(addr->port); 625 u8 hmac[SHA256_DIGEST_SIZE]; 626 u8 msg[19]; 627 int i = 0; 628 629 msg[i++] = addr->id; 630 if (addr->family == AF_INET) { 631 memcpy(&msg[i], &addr->addr.s_addr, 4); 632 i += 4; 633 } 634 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 635 else if (addr->family == AF_INET6) { 636 memcpy(&msg[i], &addr->addr6.s6_addr, 16); 637 i += 16; 638 } 639 #endif 640 msg[i++] = port >> 8; 641 msg[i++] = port & 0xFF; 642 643 mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac); 644 645 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]); 646 } 647 648 static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb, 649 unsigned int *size, 650 unsigned int remaining, 651 struct mptcp_out_options *opts) 652 { 653 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 654 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 655 bool drop_other_suboptions = false; 656 unsigned int opt_size = *size; 657 bool echo; 658 int len; 659 660 /* add addr will strip the existing options, be sure to avoid breaking 661 * MPC/MPJ handshakes 662 */ 663 if (!mptcp_pm_should_add_signal(msk) || 664 (opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) || 665 !mptcp_pm_add_addr_signal(msk, skb, opt_size, remaining, &opts->addr, 666 &echo, &drop_other_suboptions)) 667 return false; 668 669 if (drop_other_suboptions) 670 remaining += opt_size; 671 len = mptcp_add_addr_len(opts->addr.family, echo, !!opts->addr.port); 672 if (remaining < len) 673 return false; 674 675 *size = len; 676 if (drop_other_suboptions) { 677 pr_debug("drop other suboptions"); 678 opts->suboptions = 0; 679 680 /* note that e.g. DSS could have written into the memory 681 * aliased by ahmac, we must reset the field here 682 * to avoid appending the hmac even for ADD_ADDR echo 683 * options 684 */ 685 opts->ahmac = 0; 686 *size -= opt_size; 687 } 688 opts->suboptions |= OPTION_MPTCP_ADD_ADDR; 689 if (!echo) { 690 opts->ahmac = add_addr_generate_hmac(msk->local_key, 691 msk->remote_key, 692 &opts->addr); 693 } 694 pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d", 695 opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port)); 696 697 return true; 698 } 699 700 static bool mptcp_established_options_rm_addr(struct sock *sk, 701 unsigned int *size, 702 unsigned int remaining, 703 struct mptcp_out_options *opts) 704 { 705 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 706 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 707 struct mptcp_rm_list rm_list; 708 int i, len; 709 710 if (!mptcp_pm_should_rm_signal(msk) || 711 !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list))) 712 return false; 713 714 len = mptcp_rm_addr_len(&rm_list); 715 if (len < 0) 716 return false; 717 if (remaining < len) 718 return false; 719 720 *size = len; 721 opts->suboptions |= OPTION_MPTCP_RM_ADDR; 722 opts->rm_list = rm_list; 723 724 for (i = 0; i < opts->rm_list.nr; i++) 725 pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]); 726 727 return true; 728 } 729 730 static bool mptcp_established_options_mp_prio(struct sock *sk, 731 unsigned int *size, 732 unsigned int remaining, 733 struct mptcp_out_options *opts) 734 { 735 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 736 737 /* can't send MP_PRIO with MPC, as they share the same option space: 738 * 'backup'. Also it makes no sense at all 739 */ 740 if (!subflow->send_mp_prio || (opts->suboptions & OPTIONS_MPTCP_MPC)) 741 return false; 742 743 /* account for the trailing 'nop' option */ 744 if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN) 745 return false; 746 747 *size = TCPOLEN_MPTCP_PRIO_ALIGN; 748 opts->suboptions |= OPTION_MPTCP_PRIO; 749 opts->backup = subflow->request_bkup; 750 751 pr_debug("prio=%d", opts->backup); 752 753 return true; 754 } 755 756 static noinline bool mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb, 757 unsigned int *size, 758 unsigned int remaining, 759 struct mptcp_out_options *opts) 760 { 761 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 762 763 if (remaining < TCPOLEN_MPTCP_RST) 764 return false; 765 766 *size = TCPOLEN_MPTCP_RST; 767 opts->suboptions |= OPTION_MPTCP_RST; 768 opts->reset_transient = subflow->reset_transient; 769 opts->reset_reason = subflow->reset_reason; 770 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTTX); 771 772 return true; 773 } 774 775 static bool mptcp_established_options_fastclose(struct sock *sk, 776 unsigned int *size, 777 unsigned int remaining, 778 struct mptcp_out_options *opts) 779 { 780 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 781 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 782 783 if (likely(!subflow->send_fastclose)) 784 return false; 785 786 if (remaining < TCPOLEN_MPTCP_FASTCLOSE) 787 return false; 788 789 *size = TCPOLEN_MPTCP_FASTCLOSE; 790 opts->suboptions |= OPTION_MPTCP_FASTCLOSE; 791 opts->rcvr_key = msk->remote_key; 792 793 pr_debug("FASTCLOSE key=%llu", opts->rcvr_key); 794 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSETX); 795 return true; 796 } 797 798 static bool mptcp_established_options_mp_fail(struct sock *sk, 799 unsigned int *size, 800 unsigned int remaining, 801 struct mptcp_out_options *opts) 802 { 803 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 804 805 if (likely(!subflow->send_mp_fail)) 806 return false; 807 808 if (remaining < TCPOLEN_MPTCP_FAIL) 809 return false; 810 811 *size = TCPOLEN_MPTCP_FAIL; 812 opts->suboptions |= OPTION_MPTCP_FAIL; 813 opts->fail_seq = subflow->map_seq; 814 815 pr_debug("MP_FAIL fail_seq=%llu", opts->fail_seq); 816 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX); 817 818 return true; 819 } 820 821 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, 822 unsigned int *size, unsigned int remaining, 823 struct mptcp_out_options *opts) 824 { 825 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 826 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 827 unsigned int opt_size = 0; 828 bool snd_data_fin; 829 bool ret = false; 830 831 opts->suboptions = 0; 832 833 if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb))) 834 return false; 835 836 if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) { 837 if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) || 838 mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) { 839 *size += opt_size; 840 remaining -= opt_size; 841 } 842 /* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */ 843 if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) { 844 *size += opt_size; 845 remaining -= opt_size; 846 } 847 return true; 848 } 849 850 snd_data_fin = mptcp_data_fin_enabled(msk); 851 if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, opts)) 852 ret = true; 853 else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, opts)) { 854 unsigned int mp_fail_size; 855 856 ret = true; 857 if (mptcp_established_options_mp_fail(sk, &mp_fail_size, 858 remaining - opt_size, opts)) { 859 *size += opt_size + mp_fail_size; 860 remaining -= opt_size - mp_fail_size; 861 return true; 862 } 863 } 864 865 /* we reserved enough space for the above options, and exceeding the 866 * TCP option space would be fatal 867 */ 868 if (WARN_ON_ONCE(opt_size > remaining)) 869 return false; 870 871 *size += opt_size; 872 remaining -= opt_size; 873 if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) { 874 *size += opt_size; 875 remaining -= opt_size; 876 ret = true; 877 } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) { 878 *size += opt_size; 879 remaining -= opt_size; 880 ret = true; 881 } 882 883 if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) { 884 *size += opt_size; 885 remaining -= opt_size; 886 ret = true; 887 } 888 889 return ret; 890 } 891 892 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, 893 struct mptcp_out_options *opts) 894 { 895 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 896 897 if (subflow_req->mp_capable) { 898 opts->suboptions = OPTION_MPTCP_MPC_SYNACK; 899 opts->sndr_key = subflow_req->local_key; 900 opts->csum_reqd = subflow_req->csum_reqd; 901 opts->allow_join_id0 = subflow_req->allow_join_id0; 902 *size = TCPOLEN_MPTCP_MPC_SYNACK; 903 pr_debug("subflow_req=%p, local_key=%llu", 904 subflow_req, subflow_req->local_key); 905 return true; 906 } else if (subflow_req->mp_join) { 907 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK; 908 opts->backup = subflow_req->backup; 909 opts->join_id = subflow_req->local_id; 910 opts->thmac = subflow_req->thmac; 911 opts->nonce = subflow_req->local_nonce; 912 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u", 913 subflow_req, opts->backup, opts->join_id, 914 opts->thmac, opts->nonce); 915 *size = TCPOLEN_MPTCP_MPJ_SYNACK; 916 return true; 917 } 918 return false; 919 } 920 921 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 922 struct mptcp_subflow_context *subflow, 923 struct sk_buff *skb, 924 struct mptcp_options_received *mp_opt) 925 { 926 /* here we can process OoO, in-window pkts, only in-sequence 4th ack 927 * will make the subflow fully established 928 */ 929 if (likely(subflow->fully_established)) { 930 /* on passive sockets, check for 3rd ack retransmission 931 * note that msk is always set by subflow_syn_recv_sock() 932 * for mp_join subflows 933 */ 934 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 && 935 TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq && 936 subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) && 937 !subflow->request_join) 938 tcp_send_ack(ssk); 939 goto check_notify; 940 } 941 942 /* we must process OoO packets before the first subflow is fully 943 * established. OoO packets are instead a protocol violation 944 * for MP_JOIN subflows as the peer must not send any data 945 * before receiving the forth ack - cfr. RFC 8684 section 3.2. 946 */ 947 if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) { 948 if (subflow->mp_join) 949 goto reset; 950 if (subflow->is_mptfo && mp_opt->suboptions & OPTION_MPTCP_MPC_ACK) 951 goto set_fully_established; 952 return subflow->mp_capable; 953 } 954 955 if (subflow->remote_key_valid && 956 (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) || 957 ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo))) { 958 /* subflows are fully established as soon as we get any 959 * additional ack, including ADD_ADDR. 960 */ 961 subflow->fully_established = 1; 962 WRITE_ONCE(msk->fully_established, true); 963 goto check_notify; 964 } 965 966 /* If the first established packet does not contain MP_CAPABLE + data 967 * then fallback to TCP. Fallback scenarios requires a reset for 968 * MP_JOIN subflows. 969 */ 970 if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) { 971 if (subflow->mp_join) 972 goto reset; 973 subflow->mp_capable = 0; 974 pr_fallback(msk); 975 mptcp_do_fallback(ssk); 976 return false; 977 } 978 979 if (mp_opt->deny_join_id0) 980 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 981 982 set_fully_established: 983 if (unlikely(!READ_ONCE(msk->pm.server_side))) 984 pr_warn_once("bogus mpc option on established client sk"); 985 mptcp_subflow_fully_established(subflow, mp_opt); 986 987 check_notify: 988 /* if the subflow is not already linked into the conn_list, we can't 989 * notify the PM: this subflow is still on the listener queue 990 * and the PM possibly acquiring the subflow lock could race with 991 * the listener close 992 */ 993 if (likely(subflow->pm_notified) || list_empty(&subflow->node)) 994 return true; 995 996 subflow->pm_notified = 1; 997 if (subflow->mp_join) { 998 clear_3rdack_retransmission(ssk); 999 mptcp_pm_subflow_established(msk); 1000 } else { 1001 mptcp_pm_fully_established(msk, ssk); 1002 } 1003 return true; 1004 1005 reset: 1006 mptcp_subflow_reset(ssk); 1007 return false; 1008 } 1009 1010 u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq) 1011 { 1012 u32 old_seq32, cur_seq32; 1013 1014 old_seq32 = (u32)old_seq; 1015 cur_seq32 = (u32)cur_seq; 1016 cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32; 1017 if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32))) 1018 return cur_seq + (1LL << 32); 1019 1020 /* reverse wrap could happen, too */ 1021 if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32))) 1022 return cur_seq - (1LL << 32); 1023 return cur_seq; 1024 } 1025 1026 static void ack_update_msk(struct mptcp_sock *msk, 1027 struct sock *ssk, 1028 struct mptcp_options_received *mp_opt) 1029 { 1030 u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt); 1031 struct sock *sk = (struct sock *)msk; 1032 u64 old_snd_una; 1033 1034 mptcp_data_lock(sk); 1035 1036 /* avoid ack expansion on update conflict, to reduce the risk of 1037 * wrongly expanding to a future ack sequence number, which is way 1038 * more dangerous than missing an ack 1039 */ 1040 old_snd_una = msk->snd_una; 1041 new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64); 1042 1043 /* ACK for data not even sent yet? Ignore.*/ 1044 if (unlikely(after64(new_snd_una, snd_nxt))) 1045 new_snd_una = old_snd_una; 1046 1047 new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd; 1048 1049 if (after64(new_wnd_end, msk->wnd_end)) 1050 msk->wnd_end = new_wnd_end; 1051 1052 /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */ 1053 if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt))) 1054 __mptcp_check_push(sk, ssk); 1055 1056 if (after64(new_snd_una, old_snd_una)) { 1057 msk->snd_una = new_snd_una; 1058 __mptcp_data_acked(sk); 1059 } 1060 mptcp_data_unlock(sk); 1061 1062 trace_ack_update_msk(mp_opt->data_ack, 1063 old_snd_una, new_snd_una, 1064 new_wnd_end, msk->wnd_end); 1065 } 1066 1067 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit) 1068 { 1069 /* Skip if DATA_FIN was already received. 1070 * If updating simultaneously with the recvmsg loop, values 1071 * should match. If they mismatch, the peer is misbehaving and 1072 * we will prefer the most recent information. 1073 */ 1074 if (READ_ONCE(msk->rcv_data_fin)) 1075 return false; 1076 1077 WRITE_ONCE(msk->rcv_data_fin_seq, 1078 mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit)); 1079 WRITE_ONCE(msk->rcv_data_fin, 1); 1080 1081 return true; 1082 } 1083 1084 static bool add_addr_hmac_valid(struct mptcp_sock *msk, 1085 struct mptcp_options_received *mp_opt) 1086 { 1087 u64 hmac = 0; 1088 1089 if (mp_opt->echo) 1090 return true; 1091 1092 hmac = add_addr_generate_hmac(msk->remote_key, 1093 msk->local_key, 1094 &mp_opt->addr); 1095 1096 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n", 1097 msk, hmac, mp_opt->ahmac); 1098 1099 return hmac == mp_opt->ahmac; 1100 } 1101 1102 /* Return false if a subflow has been reset, else return true */ 1103 bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 1104 { 1105 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1106 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 1107 struct mptcp_options_received mp_opt; 1108 struct mptcp_ext *mpext; 1109 1110 if (__mptcp_check_fallback(msk)) { 1111 /* Keep it simple and unconditionally trigger send data cleanup and 1112 * pending queue spooling. We will need to acquire the data lock 1113 * for more accurate checks, and once the lock is acquired, such 1114 * helpers are cheap. 1115 */ 1116 mptcp_data_lock(subflow->conn); 1117 if (sk_stream_memory_free(sk)) 1118 __mptcp_check_push(subflow->conn, sk); 1119 __mptcp_data_acked(subflow->conn); 1120 mptcp_data_unlock(subflow->conn); 1121 return true; 1122 } 1123 1124 mptcp_get_options(skb, &mp_opt); 1125 1126 /* The subflow can be in close state only if check_fully_established() 1127 * just sent a reset. If so, tell the caller to ignore the current packet. 1128 */ 1129 if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) 1130 return sk->sk_state != TCP_CLOSE; 1131 1132 if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) { 1133 if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) && 1134 msk->local_key == mp_opt.rcvr_key) { 1135 WRITE_ONCE(msk->rcv_fastclose, true); 1136 mptcp_schedule_work((struct sock *)msk); 1137 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX); 1138 } 1139 1140 if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) && 1141 add_addr_hmac_valid(msk, &mp_opt)) { 1142 if (!mp_opt.echo) { 1143 mptcp_pm_add_addr_received(sk, &mp_opt.addr); 1144 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR); 1145 } else { 1146 mptcp_pm_add_addr_echoed(msk, &mp_opt.addr); 1147 mptcp_pm_del_add_timer(msk, &mp_opt.addr, true); 1148 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD); 1149 } 1150 1151 if (mp_opt.addr.port) 1152 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD); 1153 } 1154 1155 if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR) 1156 mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list); 1157 1158 if (mp_opt.suboptions & OPTION_MPTCP_PRIO) { 1159 mptcp_pm_mp_prio_received(sk, mp_opt.backup); 1160 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX); 1161 } 1162 1163 if (mp_opt.suboptions & OPTION_MPTCP_FAIL) { 1164 mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq); 1165 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX); 1166 } 1167 1168 if (mp_opt.suboptions & OPTION_MPTCP_RST) { 1169 subflow->reset_seen = 1; 1170 subflow->reset_reason = mp_opt.reset_reason; 1171 subflow->reset_transient = mp_opt.reset_transient; 1172 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTRX); 1173 } 1174 1175 if (!(mp_opt.suboptions & OPTION_MPTCP_DSS)) 1176 return true; 1177 } 1178 1179 /* we can't wait for recvmsg() to update the ack_seq, otherwise 1180 * monodirectional flows will stuck 1181 */ 1182 if (mp_opt.use_ack) 1183 ack_update_msk(msk, sk, &mp_opt); 1184 1185 /* Zero-data-length packets are dropped by the caller and not 1186 * propagated to the MPTCP layer, so the skb extension does not 1187 * need to be allocated or populated. DATA_FIN information, if 1188 * present, needs to be updated here before the skb is freed. 1189 */ 1190 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) { 1191 if (mp_opt.data_fin && mp_opt.data_len == 1 && 1192 mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64)) 1193 mptcp_schedule_work((struct sock *)msk); 1194 1195 return true; 1196 } 1197 1198 mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 1199 if (!mpext) 1200 return true; 1201 1202 memset(mpext, 0, sizeof(*mpext)); 1203 1204 if (likely(mp_opt.use_map)) { 1205 if (mp_opt.mpc_map) { 1206 /* this is an MP_CAPABLE carrying MPTCP data 1207 * we know this map the first chunk of data 1208 */ 1209 mptcp_crypto_key_sha(subflow->remote_key, NULL, 1210 &mpext->data_seq); 1211 mpext->data_seq++; 1212 mpext->subflow_seq = 1; 1213 mpext->dsn64 = 1; 1214 mpext->mpc_map = 1; 1215 mpext->data_fin = 0; 1216 } else { 1217 mpext->data_seq = mp_opt.data_seq; 1218 mpext->subflow_seq = mp_opt.subflow_seq; 1219 mpext->dsn64 = mp_opt.dsn64; 1220 mpext->data_fin = mp_opt.data_fin; 1221 } 1222 mpext->data_len = mp_opt.data_len; 1223 mpext->use_map = 1; 1224 mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD); 1225 1226 if (mpext->csum_reqd) 1227 mpext->csum = mp_opt.csum; 1228 } 1229 1230 return true; 1231 } 1232 1233 static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th) 1234 { 1235 const struct sock *ssk = (const struct sock *)tp; 1236 struct mptcp_subflow_context *subflow; 1237 u64 ack_seq, rcv_wnd_old, rcv_wnd_new; 1238 struct mptcp_sock *msk; 1239 u32 new_win; 1240 u64 win; 1241 1242 subflow = mptcp_subflow_ctx(ssk); 1243 msk = mptcp_sk(subflow->conn); 1244 1245 ack_seq = READ_ONCE(msk->ack_seq); 1246 rcv_wnd_new = ack_seq + tp->rcv_wnd; 1247 1248 rcv_wnd_old = atomic64_read(&msk->rcv_wnd_sent); 1249 if (after64(rcv_wnd_new, rcv_wnd_old)) { 1250 u64 rcv_wnd; 1251 1252 for (;;) { 1253 rcv_wnd = atomic64_cmpxchg(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new); 1254 1255 if (rcv_wnd == rcv_wnd_old) 1256 break; 1257 if (before64(rcv_wnd_new, rcv_wnd)) { 1258 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE); 1259 goto raise_win; 1260 } 1261 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT); 1262 rcv_wnd_old = rcv_wnd; 1263 } 1264 return; 1265 } 1266 1267 if (rcv_wnd_new != rcv_wnd_old) { 1268 raise_win: 1269 win = rcv_wnd_old - ack_seq; 1270 tp->rcv_wnd = min_t(u64, win, U32_MAX); 1271 new_win = tp->rcv_wnd; 1272 1273 /* Make sure we do not exceed the maximum possible 1274 * scaled window. 1275 */ 1276 if (unlikely(th->syn)) 1277 new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale; 1278 if (!tp->rx_opt.rcv_wscale && 1279 READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows)) 1280 new_win = min(new_win, MAX_TCP_WINDOW); 1281 else 1282 new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 1283 1284 /* RFC1323 scaling applied */ 1285 new_win >>= tp->rx_opt.rcv_wscale; 1286 th->window = htons(new_win); 1287 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED); 1288 } 1289 } 1290 1291 __sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum) 1292 { 1293 struct csum_pseudo_header header; 1294 __wsum csum; 1295 1296 /* cfr RFC 8684 3.3.1.: 1297 * the data sequence number used in the pseudo-header is 1298 * always the 64-bit value, irrespective of what length is used in the 1299 * DSS option itself. 1300 */ 1301 header.data_seq = cpu_to_be64(data_seq); 1302 header.subflow_seq = htonl(subflow_seq); 1303 header.data_len = htons(data_len); 1304 header.csum = 0; 1305 1306 csum = csum_partial(&header, sizeof(header), sum); 1307 return csum_fold(csum); 1308 } 1309 1310 static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext) 1311 { 1312 return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len, 1313 ~csum_unfold(mpext->csum)); 1314 } 1315 1316 static void put_len_csum(u16 len, __sum16 csum, void *data) 1317 { 1318 __sum16 *sumptr = data + 2; 1319 __be16 *ptr = data; 1320 1321 put_unaligned_be16(len, ptr); 1322 1323 put_unaligned(csum, sumptr); 1324 } 1325 1326 void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp, 1327 struct mptcp_out_options *opts) 1328 { 1329 const struct sock *ssk = (const struct sock *)tp; 1330 struct mptcp_subflow_context *subflow; 1331 1332 /* Which options can be used together? 1333 * 1334 * X: mutually exclusive 1335 * O: often used together 1336 * C: can be used together in some cases 1337 * P: could be used together but we prefer not to (optimisations) 1338 * 1339 * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | 1340 * ------|------|------|------|------|------|------|------|------| 1341 * MPC |------|------|------|------|------|------|------|------| 1342 * MPJ | X |------|------|------|------|------|------|------| 1343 * DSS | X | X |------|------|------|------|------|------| 1344 * ADD | X | X | P |------|------|------|------|------| 1345 * RM | C | C | C | P |------|------|------|------| 1346 * PRIO | X | C | C | C | C |------|------|------| 1347 * FAIL | X | X | C | X | X | X |------|------| 1348 * FC | X | X | X | X | X | X | X |------| 1349 * RST | X | X | X | X | X | X | O | O | 1350 * ------|------|------|------|------|------|------|------|------| 1351 * 1352 * The same applies in mptcp_established_options() function. 1353 */ 1354 if (likely(OPTION_MPTCP_DSS & opts->suboptions)) { 1355 struct mptcp_ext *mpext = &opts->ext_copy; 1356 u8 len = TCPOLEN_MPTCP_DSS_BASE; 1357 u8 flags = 0; 1358 1359 if (mpext->use_ack) { 1360 flags = MPTCP_DSS_HAS_ACK; 1361 if (mpext->ack64) { 1362 len += TCPOLEN_MPTCP_DSS_ACK64; 1363 flags |= MPTCP_DSS_ACK64; 1364 } else { 1365 len += TCPOLEN_MPTCP_DSS_ACK32; 1366 } 1367 } 1368 1369 if (mpext->use_map) { 1370 len += TCPOLEN_MPTCP_DSS_MAP64; 1371 1372 /* Use only 64-bit mapping flags for now, add 1373 * support for optional 32-bit mappings later. 1374 */ 1375 flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64; 1376 if (mpext->data_fin) 1377 flags |= MPTCP_DSS_DATA_FIN; 1378 1379 if (opts->csum_reqd) 1380 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1381 } 1382 1383 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags); 1384 1385 if (mpext->use_ack) { 1386 if (mpext->ack64) { 1387 put_unaligned_be64(mpext->data_ack, ptr); 1388 ptr += 2; 1389 } else { 1390 put_unaligned_be32(mpext->data_ack32, ptr); 1391 ptr += 1; 1392 } 1393 } 1394 1395 if (mpext->use_map) { 1396 put_unaligned_be64(mpext->data_seq, ptr); 1397 ptr += 2; 1398 put_unaligned_be32(mpext->subflow_seq, ptr); 1399 ptr += 1; 1400 if (opts->csum_reqd) { 1401 /* data_len == 0 is reserved for the infinite mapping, 1402 * the checksum will also be set to 0. 1403 */ 1404 put_len_csum(mpext->data_len, 1405 (mpext->data_len ? mptcp_make_csum(mpext) : 0), 1406 ptr); 1407 } else { 1408 put_unaligned_be32(mpext->data_len << 16 | 1409 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1410 } 1411 ptr += 1; 1412 } 1413 1414 /* We might need to add MP_FAIL options in rare cases */ 1415 if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) 1416 goto mp_fail; 1417 } else if (OPTIONS_MPTCP_MPC & opts->suboptions) { 1418 u8 len, flag = MPTCP_CAP_HMAC_SHA256; 1419 1420 if (OPTION_MPTCP_MPC_SYN & opts->suboptions) { 1421 len = TCPOLEN_MPTCP_MPC_SYN; 1422 } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) { 1423 len = TCPOLEN_MPTCP_MPC_SYNACK; 1424 } else if (opts->data_len) { 1425 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 1426 if (opts->csum_reqd) 1427 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1428 } else { 1429 len = TCPOLEN_MPTCP_MPC_ACK; 1430 } 1431 1432 if (opts->csum_reqd) 1433 flag |= MPTCP_CAP_CHECKSUM_REQD; 1434 1435 if (!opts->allow_join_id0) 1436 flag |= MPTCP_CAP_DENY_JOIN_ID0; 1437 1438 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len, 1439 MPTCP_SUPPORTED_VERSION, 1440 flag); 1441 1442 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) & 1443 opts->suboptions)) 1444 goto mp_capable_done; 1445 1446 put_unaligned_be64(opts->sndr_key, ptr); 1447 ptr += 2; 1448 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions)) 1449 goto mp_capable_done; 1450 1451 put_unaligned_be64(opts->rcvr_key, ptr); 1452 ptr += 2; 1453 if (!opts->data_len) 1454 goto mp_capable_done; 1455 1456 if (opts->csum_reqd) { 1457 put_len_csum(opts->data_len, 1458 __mptcp_make_csum(opts->data_seq, 1459 opts->subflow_seq, 1460 opts->data_len, 1461 ~csum_unfold(opts->csum)), 1462 ptr); 1463 } else { 1464 put_unaligned_be32(opts->data_len << 16 | 1465 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1466 } 1467 ptr += 1; 1468 1469 /* MPC is additionally mutually exclusive with MP_PRIO */ 1470 goto mp_capable_done; 1471 } else if (OPTIONS_MPTCP_MPJ & opts->suboptions) { 1472 if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) { 1473 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1474 TCPOLEN_MPTCP_MPJ_SYN, 1475 opts->backup, opts->join_id); 1476 put_unaligned_be32(opts->token, ptr); 1477 ptr += 1; 1478 put_unaligned_be32(opts->nonce, ptr); 1479 ptr += 1; 1480 } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) { 1481 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1482 TCPOLEN_MPTCP_MPJ_SYNACK, 1483 opts->backup, opts->join_id); 1484 put_unaligned_be64(opts->thmac, ptr); 1485 ptr += 2; 1486 put_unaligned_be32(opts->nonce, ptr); 1487 ptr += 1; 1488 } else { 1489 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1490 TCPOLEN_MPTCP_MPJ_ACK, 0, 0); 1491 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN); 1492 ptr += 5; 1493 } 1494 } else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) { 1495 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE; 1496 u8 echo = MPTCP_ADDR_ECHO; 1497 1498 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1499 if (opts->addr.family == AF_INET6) 1500 len = TCPOLEN_MPTCP_ADD_ADDR6_BASE; 1501 #endif 1502 1503 if (opts->addr.port) 1504 len += TCPOLEN_MPTCP_PORT_LEN; 1505 1506 if (opts->ahmac) { 1507 len += sizeof(opts->ahmac); 1508 echo = 0; 1509 } 1510 1511 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR, 1512 len, echo, opts->addr.id); 1513 if (opts->addr.family == AF_INET) { 1514 memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4); 1515 ptr += 1; 1516 } 1517 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1518 else if (opts->addr.family == AF_INET6) { 1519 memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16); 1520 ptr += 4; 1521 } 1522 #endif 1523 1524 if (!opts->addr.port) { 1525 if (opts->ahmac) { 1526 put_unaligned_be64(opts->ahmac, ptr); 1527 ptr += 2; 1528 } 1529 } else { 1530 u16 port = ntohs(opts->addr.port); 1531 1532 if (opts->ahmac) { 1533 u8 *bptr = (u8 *)ptr; 1534 1535 put_unaligned_be16(port, bptr); 1536 bptr += 2; 1537 put_unaligned_be64(opts->ahmac, bptr); 1538 bptr += 8; 1539 put_unaligned_be16(TCPOPT_NOP << 8 | 1540 TCPOPT_NOP, bptr); 1541 1542 ptr += 3; 1543 } else { 1544 put_unaligned_be32(port << 16 | 1545 TCPOPT_NOP << 8 | 1546 TCPOPT_NOP, ptr); 1547 ptr += 1; 1548 } 1549 } 1550 } else if (unlikely(OPTION_MPTCP_FASTCLOSE & opts->suboptions)) { 1551 /* FASTCLOSE is mutually exclusive with others except RST */ 1552 *ptr++ = mptcp_option(MPTCPOPT_MP_FASTCLOSE, 1553 TCPOLEN_MPTCP_FASTCLOSE, 1554 0, 0); 1555 put_unaligned_be64(opts->rcvr_key, ptr); 1556 ptr += 2; 1557 1558 if (OPTION_MPTCP_RST & opts->suboptions) 1559 goto mp_rst; 1560 return; 1561 } else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) { 1562 mp_fail: 1563 /* MP_FAIL is mutually exclusive with others except RST */ 1564 subflow = mptcp_subflow_ctx(ssk); 1565 subflow->send_mp_fail = 0; 1566 1567 *ptr++ = mptcp_option(MPTCPOPT_MP_FAIL, 1568 TCPOLEN_MPTCP_FAIL, 1569 0, 0); 1570 put_unaligned_be64(opts->fail_seq, ptr); 1571 ptr += 2; 1572 1573 if (OPTION_MPTCP_RST & opts->suboptions) 1574 goto mp_rst; 1575 return; 1576 } else if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) { 1577 mp_rst: 1578 *ptr++ = mptcp_option(MPTCPOPT_RST, 1579 TCPOLEN_MPTCP_RST, 1580 opts->reset_transient, 1581 opts->reset_reason); 1582 return; 1583 } 1584 1585 if (OPTION_MPTCP_PRIO & opts->suboptions) { 1586 subflow = mptcp_subflow_ctx(ssk); 1587 subflow->send_mp_prio = 0; 1588 1589 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO, 1590 TCPOLEN_MPTCP_PRIO, 1591 opts->backup, TCPOPT_NOP); 1592 1593 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPPRIOTX); 1594 } 1595 1596 mp_capable_done: 1597 if (OPTION_MPTCP_RM_ADDR & opts->suboptions) { 1598 u8 i = 1; 1599 1600 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR, 1601 TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr, 1602 0, opts->rm_list.ids[0]); 1603 1604 while (i < opts->rm_list.nr) { 1605 u8 id1, id2, id3, id4; 1606 1607 id1 = opts->rm_list.ids[i]; 1608 id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP; 1609 id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP; 1610 id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP; 1611 put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr); 1612 ptr += 1; 1613 i += 4; 1614 } 1615 } 1616 1617 if (tp) 1618 mptcp_set_rwin(tp, th); 1619 } 1620 1621 __be32 mptcp_get_reset_option(const struct sk_buff *skb) 1622 { 1623 const struct mptcp_ext *ext = mptcp_get_ext(skb); 1624 u8 flags, reason; 1625 1626 if (ext) { 1627 flags = ext->reset_transient; 1628 reason = ext->reset_reason; 1629 1630 return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST, 1631 flags, reason); 1632 } 1633 1634 return htonl(0u); 1635 } 1636 EXPORT_SYMBOL_GPL(mptcp_get_reset_option); 1637