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