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