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