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->csum_reqd = 1; 85 86 if (flags & MPTCP_CAP_DENY_JOIN_ID0) 87 mp_opt->deny_join_id0 = 1; 88 89 mp_opt->mp_capable = 1; 90 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) { 91 mp_opt->sndr_key = get_unaligned_be64(ptr); 92 ptr += 8; 93 } 94 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) { 95 mp_opt->rcvr_key = get_unaligned_be64(ptr); 96 ptr += 8; 97 } 98 if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) { 99 /* Section 3.1.: 100 * "the data parameters in a MP_CAPABLE are semantically 101 * equivalent to those in a DSS option and can be used 102 * interchangeably." 103 */ 104 mp_opt->dss = 1; 105 mp_opt->use_map = 1; 106 mp_opt->mpc_map = 1; 107 mp_opt->data_len = get_unaligned_be16(ptr); 108 ptr += 2; 109 } 110 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) { 111 mp_opt->csum = (__force __sum16)get_unaligned_be16(ptr); 112 mp_opt->csum_reqd = 1; 113 ptr += 2; 114 } 115 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u", 116 version, flags, opsize, mp_opt->sndr_key, 117 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum); 118 break; 119 120 case MPTCPOPT_MP_JOIN: 121 mp_opt->mp_join = 1; 122 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) { 123 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 124 mp_opt->join_id = *ptr++; 125 mp_opt->token = get_unaligned_be32(ptr); 126 ptr += 4; 127 mp_opt->nonce = get_unaligned_be32(ptr); 128 ptr += 4; 129 pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u", 130 mp_opt->backup, mp_opt->join_id, 131 mp_opt->token, mp_opt->nonce); 132 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) { 133 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 134 mp_opt->join_id = *ptr++; 135 mp_opt->thmac = get_unaligned_be64(ptr); 136 ptr += 8; 137 mp_opt->nonce = get_unaligned_be32(ptr); 138 ptr += 4; 139 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u", 140 mp_opt->backup, mp_opt->join_id, 141 mp_opt->thmac, mp_opt->nonce); 142 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) { 143 ptr += 2; 144 memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN); 145 pr_debug("MP_JOIN hmac"); 146 } else { 147 mp_opt->mp_join = 0; 148 } 149 break; 150 151 case MPTCPOPT_DSS: 152 pr_debug("DSS"); 153 ptr++; 154 155 /* we must clear 'mpc_map' be able to detect MP_CAPABLE 156 * map vs DSS map in mptcp_incoming_options(), and reconstruct 157 * map info accordingly 158 */ 159 mp_opt->mpc_map = 0; 160 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK; 161 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0; 162 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0; 163 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0; 164 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0; 165 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK); 166 167 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d", 168 mp_opt->data_fin, mp_opt->dsn64, 169 mp_opt->use_map, mp_opt->ack64, 170 mp_opt->use_ack); 171 172 expected_opsize = TCPOLEN_MPTCP_DSS_BASE; 173 174 if (mp_opt->use_ack) { 175 if (mp_opt->ack64) 176 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64; 177 else 178 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32; 179 } 180 181 if (mp_opt->use_map) { 182 if (mp_opt->dsn64) 183 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64; 184 else 185 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32; 186 } 187 188 /* Always parse any csum presence combination, we will enforce 189 * RFC 8684 Section 3.3.0 checks later in subflow_data_ready 190 */ 191 if (opsize != expected_opsize && 192 opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) 193 break; 194 195 mp_opt->dss = 1; 196 197 if (mp_opt->use_ack) { 198 if (mp_opt->ack64) { 199 mp_opt->data_ack = get_unaligned_be64(ptr); 200 ptr += 8; 201 } else { 202 mp_opt->data_ack = get_unaligned_be32(ptr); 203 ptr += 4; 204 } 205 206 pr_debug("data_ack=%llu", mp_opt->data_ack); 207 } 208 209 if (mp_opt->use_map) { 210 if (mp_opt->dsn64) { 211 mp_opt->data_seq = get_unaligned_be64(ptr); 212 ptr += 8; 213 } else { 214 mp_opt->data_seq = get_unaligned_be32(ptr); 215 ptr += 4; 216 } 217 218 mp_opt->subflow_seq = get_unaligned_be32(ptr); 219 ptr += 4; 220 221 mp_opt->data_len = get_unaligned_be16(ptr); 222 ptr += 2; 223 224 if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { 225 mp_opt->csum_reqd = 1; 226 mp_opt->csum = (__force __sum16)get_unaligned_be16(ptr); 227 ptr += 2; 228 } 229 230 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u", 231 mp_opt->data_seq, mp_opt->subflow_seq, 232 mp_opt->data_len, mp_opt->csum_reqd, mp_opt->csum); 233 } 234 235 break; 236 237 case MPTCPOPT_ADD_ADDR: 238 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO; 239 if (!mp_opt->echo) { 240 if (opsize == TCPOLEN_MPTCP_ADD_ADDR || 241 opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT) 242 mp_opt->addr.family = AF_INET; 243 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 244 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 || 245 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT) 246 mp_opt->addr.family = AF_INET6; 247 #endif 248 else 249 break; 250 } else { 251 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE || 252 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) 253 mp_opt->addr.family = AF_INET; 254 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 255 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE || 256 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) 257 mp_opt->addr.family = AF_INET6; 258 #endif 259 else 260 break; 261 } 262 263 mp_opt->add_addr = 1; 264 mp_opt->addr.id = *ptr++; 265 if (mp_opt->addr.family == AF_INET) { 266 memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4); 267 ptr += 4; 268 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT || 269 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) { 270 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 271 ptr += 2; 272 } 273 } 274 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 275 else { 276 memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16); 277 ptr += 16; 278 if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT || 279 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) { 280 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 281 ptr += 2; 282 } 283 } 284 #endif 285 if (!mp_opt->echo) { 286 mp_opt->ahmac = get_unaligned_be64(ptr); 287 ptr += 8; 288 } 289 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d", 290 (mp_opt->addr.family == AF_INET6) ? "6" : "", 291 mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port)); 292 break; 293 294 case MPTCPOPT_RM_ADDR: 295 if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 || 296 opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX) 297 break; 298 299 ptr++; 300 301 mp_opt->rm_addr = 1; 302 mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE; 303 for (i = 0; i < mp_opt->rm_list.nr; i++) 304 mp_opt->rm_list.ids[i] = *ptr++; 305 pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr); 306 break; 307 308 case MPTCPOPT_MP_PRIO: 309 if (opsize != TCPOLEN_MPTCP_PRIO) 310 break; 311 312 mp_opt->mp_prio = 1; 313 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP; 314 pr_debug("MP_PRIO: prio=%d", mp_opt->backup); 315 break; 316 317 case MPTCPOPT_MP_FASTCLOSE: 318 if (opsize != TCPOLEN_MPTCP_FASTCLOSE) 319 break; 320 321 ptr += 2; 322 mp_opt->rcvr_key = get_unaligned_be64(ptr); 323 ptr += 8; 324 mp_opt->fastclose = 1; 325 break; 326 327 case MPTCPOPT_RST: 328 if (opsize != TCPOLEN_MPTCP_RST) 329 break; 330 331 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) 332 break; 333 mp_opt->reset = 1; 334 flags = *ptr++; 335 mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT; 336 mp_opt->reset_reason = *ptr; 337 break; 338 339 default: 340 break; 341 } 342 } 343 344 void mptcp_get_options(const struct sock *sk, 345 const struct sk_buff *skb, 346 struct mptcp_options_received *mp_opt) 347 { 348 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 349 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 350 const struct tcphdr *th = tcp_hdr(skb); 351 const unsigned char *ptr; 352 int length; 353 354 /* initialize option status */ 355 mp_opt->mp_capable = 0; 356 mp_opt->mp_join = 0; 357 mp_opt->add_addr = 0; 358 mp_opt->ahmac = 0; 359 mp_opt->fastclose = 0; 360 mp_opt->addr.port = 0; 361 mp_opt->rm_addr = 0; 362 mp_opt->dss = 0; 363 mp_opt->mp_prio = 0; 364 mp_opt->reset = 0; 365 mp_opt->csum_reqd = READ_ONCE(msk->csum_enabled); 366 mp_opt->deny_join_id0 = 0; 367 368 length = (th->doff * 4) - sizeof(struct tcphdr); 369 ptr = (const unsigned char *)(th + 1); 370 371 while (length > 0) { 372 int opcode = *ptr++; 373 int opsize; 374 375 switch (opcode) { 376 case TCPOPT_EOL: 377 return; 378 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ 379 length--; 380 continue; 381 default: 382 if (length < 2) 383 return; 384 opsize = *ptr++; 385 if (opsize < 2) /* "silly options" */ 386 return; 387 if (opsize > length) 388 return; /* don't parse partial options */ 389 if (opcode == TCPOPT_MPTCP) 390 mptcp_parse_option(skb, ptr, opsize, mp_opt); 391 ptr += opsize - 2; 392 length -= opsize; 393 } 394 } 395 } 396 397 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb, 398 unsigned int *size, struct mptcp_out_options *opts) 399 { 400 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 401 402 /* we will use snd_isn to detect first pkt [re]transmission 403 * in mptcp_established_options_mp() 404 */ 405 subflow->snd_isn = TCP_SKB_CB(skb)->end_seq; 406 if (subflow->request_mptcp) { 407 opts->suboptions = OPTION_MPTCP_MPC_SYN; 408 opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk)); 409 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 410 *size = TCPOLEN_MPTCP_MPC_SYN; 411 return true; 412 } else if (subflow->request_join) { 413 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token, 414 subflow->local_nonce); 415 opts->suboptions = OPTION_MPTCP_MPJ_SYN; 416 opts->join_id = subflow->local_id; 417 opts->token = subflow->remote_token; 418 opts->nonce = subflow->local_nonce; 419 opts->backup = subflow->request_bkup; 420 *size = TCPOLEN_MPTCP_MPJ_SYN; 421 return true; 422 } 423 return false; 424 } 425 426 /* MP_JOIN client subflow must wait for 4th ack before sending any data: 427 * TCP can't schedule delack timer before the subflow is fully established. 428 * MPTCP uses the delack timer to do 3rd ack retransmissions 429 */ 430 static void schedule_3rdack_retransmission(struct sock *sk) 431 { 432 struct inet_connection_sock *icsk = inet_csk(sk); 433 struct tcp_sock *tp = tcp_sk(sk); 434 unsigned long timeout; 435 436 /* reschedule with a timeout above RTT, as we must look only for drop */ 437 if (tp->srtt_us) 438 timeout = tp->srtt_us << 1; 439 else 440 timeout = TCP_TIMEOUT_INIT; 441 442 WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER); 443 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 444 icsk->icsk_ack.timeout = timeout; 445 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 446 } 447 448 static void clear_3rdack_retransmission(struct sock *sk) 449 { 450 struct inet_connection_sock *icsk = inet_csk(sk); 451 452 sk_stop_timer(sk, &icsk->icsk_delack_timer); 453 icsk->icsk_ack.timeout = 0; 454 icsk->icsk_ack.ato = 0; 455 icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER); 456 } 457 458 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, 459 bool snd_data_fin_enable, 460 unsigned int *size, 461 unsigned int remaining, 462 struct mptcp_out_options *opts) 463 { 464 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 465 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 466 struct mptcp_ext *mpext; 467 unsigned int data_len; 468 u8 len; 469 470 /* When skb is not available, we better over-estimate the emitted 471 * options len. A full DSS option (28 bytes) is longer than 472 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so 473 * tell the caller to defer the estimate to 474 * mptcp_established_options_dss(), which will reserve enough space. 475 */ 476 if (!skb) 477 return false; 478 479 /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */ 480 if (subflow->fully_established || snd_data_fin_enable || 481 subflow->snd_isn != TCP_SKB_CB(skb)->seq || 482 sk->sk_state != TCP_ESTABLISHED) 483 return false; 484 485 if (subflow->mp_capable) { 486 mpext = mptcp_get_ext(skb); 487 data_len = mpext ? mpext->data_len : 0; 488 489 /* we will check ext_copy.data_len in mptcp_write_options() to 490 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and 491 * TCPOLEN_MPTCP_MPC_ACK 492 */ 493 opts->ext_copy.data_len = data_len; 494 opts->suboptions = OPTION_MPTCP_MPC_ACK; 495 opts->sndr_key = subflow->local_key; 496 opts->rcvr_key = subflow->remote_key; 497 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 498 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 499 500 /* Section 3.1. 501 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK 502 * packets that start the first subflow of an MPTCP connection, 503 * as well as the first packet that carries data 504 */ 505 if (data_len > 0) { 506 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 507 if (opts->csum_reqd) { 508 /* we need to propagate more info to csum the pseudo hdr */ 509 opts->ext_copy.data_seq = mpext->data_seq; 510 opts->ext_copy.subflow_seq = mpext->subflow_seq; 511 opts->ext_copy.csum = mpext->csum; 512 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 513 } 514 *size = ALIGN(len, 4); 515 } else { 516 *size = TCPOLEN_MPTCP_MPC_ACK; 517 } 518 519 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d", 520 subflow, subflow->local_key, subflow->remote_key, 521 data_len); 522 523 return true; 524 } else if (subflow->mp_join) { 525 opts->suboptions = OPTION_MPTCP_MPJ_ACK; 526 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN); 527 *size = TCPOLEN_MPTCP_MPJ_ACK; 528 pr_debug("subflow=%p", subflow); 529 530 schedule_3rdack_retransmission(sk); 531 return true; 532 } 533 return false; 534 } 535 536 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow, 537 struct sk_buff *skb, struct mptcp_ext *ext) 538 { 539 /* The write_seq value has already been incremented, so the actual 540 * sequence number for the DATA_FIN is one less. 541 */ 542 u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1; 543 544 if (!ext->use_map || !skb->len) { 545 /* RFC6824 requires a DSS mapping with specific values 546 * if DATA_FIN is set but no data payload is mapped 547 */ 548 ext->data_fin = 1; 549 ext->use_map = 1; 550 ext->dsn64 = 1; 551 ext->data_seq = data_fin_tx_seq; 552 ext->subflow_seq = 0; 553 ext->data_len = 1; 554 } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) { 555 /* If there's an existing DSS mapping and it is the 556 * final mapping, DATA_FIN consumes 1 additional byte of 557 * mapping space. 558 */ 559 ext->data_fin = 1; 560 ext->data_len++; 561 } 562 } 563 564 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, 565 bool snd_data_fin_enable, 566 unsigned int *size, 567 unsigned int remaining, 568 struct mptcp_out_options *opts) 569 { 570 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 571 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 572 unsigned int dss_size = 0; 573 struct mptcp_ext *mpext; 574 unsigned int ack_size; 575 bool ret = false; 576 u64 ack_seq; 577 578 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 579 mpext = skb ? mptcp_get_ext(skb) : NULL; 580 581 if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) { 582 unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64; 583 584 if (mpext) { 585 if (opts->csum_reqd) 586 map_size += TCPOLEN_MPTCP_DSS_CHECKSUM; 587 588 opts->ext_copy = *mpext; 589 } 590 591 remaining -= map_size; 592 dss_size = map_size; 593 if (skb && snd_data_fin_enable) 594 mptcp_write_data_fin(subflow, skb, &opts->ext_copy); 595 ret = true; 596 } 597 598 /* passive sockets msk will set the 'can_ack' after accept(), even 599 * if the first subflow may have the already the remote key handy 600 */ 601 opts->ext_copy.use_ack = 0; 602 if (!READ_ONCE(msk->can_ack)) { 603 *size = ALIGN(dss_size, 4); 604 return ret; 605 } 606 607 ack_seq = READ_ONCE(msk->ack_seq); 608 if (READ_ONCE(msk->use_64bit_ack)) { 609 ack_size = TCPOLEN_MPTCP_DSS_ACK64; 610 opts->ext_copy.data_ack = ack_seq; 611 opts->ext_copy.ack64 = 1; 612 } else { 613 ack_size = TCPOLEN_MPTCP_DSS_ACK32; 614 opts->ext_copy.data_ack32 = (uint32_t)ack_seq; 615 opts->ext_copy.ack64 = 0; 616 } 617 opts->ext_copy.use_ack = 1; 618 WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk)); 619 620 /* Add kind/length/subtype/flag overhead if mapping is not populated */ 621 if (dss_size == 0) 622 ack_size += TCPOLEN_MPTCP_DSS_BASE; 623 624 dss_size += ack_size; 625 626 *size = ALIGN(dss_size, 4); 627 return true; 628 } 629 630 static u64 add_addr_generate_hmac(u64 key1, u64 key2, 631 struct mptcp_addr_info *addr) 632 { 633 u16 port = ntohs(addr->port); 634 u8 hmac[SHA256_DIGEST_SIZE]; 635 u8 msg[19]; 636 int i = 0; 637 638 msg[i++] = addr->id; 639 if (addr->family == AF_INET) { 640 memcpy(&msg[i], &addr->addr.s_addr, 4); 641 i += 4; 642 } 643 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 644 else if (addr->family == AF_INET6) { 645 memcpy(&msg[i], &addr->addr6.s6_addr, 16); 646 i += 16; 647 } 648 #endif 649 msg[i++] = port >> 8; 650 msg[i++] = port & 0xFF; 651 652 mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac); 653 654 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]); 655 } 656 657 static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb, 658 unsigned int *size, 659 unsigned int remaining, 660 struct mptcp_out_options *opts) 661 { 662 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 663 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 664 bool drop_other_suboptions = false; 665 unsigned int opt_size = *size; 666 bool echo; 667 bool port; 668 int len; 669 670 if ((mptcp_pm_should_add_signal_ipv6(msk) || 671 mptcp_pm_should_add_signal_port(msk) || 672 mptcp_pm_should_add_signal_echo(msk)) && 673 skb && skb_is_tcp_pure_ack(skb)) { 674 pr_debug("drop other suboptions"); 675 opts->suboptions = 0; 676 opts->ext_copy.use_ack = 0; 677 opts->ext_copy.use_map = 0; 678 remaining += opt_size; 679 drop_other_suboptions = true; 680 } 681 682 if (!mptcp_pm_should_add_signal(msk) || 683 !(mptcp_pm_add_addr_signal(msk, remaining, &opts->addr, &echo, &port))) 684 return false; 685 686 len = mptcp_add_addr_len(opts->addr.family, echo, port); 687 if (remaining < len) 688 return false; 689 690 *size = len; 691 if (drop_other_suboptions) 692 *size -= opt_size; 693 opts->suboptions |= OPTION_MPTCP_ADD_ADDR; 694 if (!echo) { 695 opts->ahmac = add_addr_generate_hmac(msk->local_key, 696 msk->remote_key, 697 &opts->addr); 698 } 699 pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d", 700 opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port)); 701 702 return true; 703 } 704 705 static bool mptcp_established_options_rm_addr(struct sock *sk, 706 unsigned int *size, 707 unsigned int remaining, 708 struct mptcp_out_options *opts) 709 { 710 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 711 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 712 struct mptcp_rm_list rm_list; 713 int i, len; 714 715 if (!mptcp_pm_should_rm_signal(msk) || 716 !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list))) 717 return false; 718 719 len = mptcp_rm_addr_len(&rm_list); 720 if (len < 0) 721 return false; 722 if (remaining < len) 723 return false; 724 725 *size = len; 726 opts->suboptions |= OPTION_MPTCP_RM_ADDR; 727 opts->rm_list = rm_list; 728 729 for (i = 0; i < opts->rm_list.nr; i++) 730 pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]); 731 732 return true; 733 } 734 735 static bool mptcp_established_options_mp_prio(struct sock *sk, 736 unsigned int *size, 737 unsigned int remaining, 738 struct mptcp_out_options *opts) 739 { 740 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 741 742 if (!subflow->send_mp_prio) 743 return false; 744 745 /* account for the trailing 'nop' option */ 746 if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN) 747 return false; 748 749 *size = TCPOLEN_MPTCP_PRIO_ALIGN; 750 opts->suboptions |= OPTION_MPTCP_PRIO; 751 opts->backup = subflow->request_bkup; 752 753 pr_debug("prio=%d", opts->backup); 754 755 return true; 756 } 757 758 static noinline void mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb, 759 unsigned int *size, 760 unsigned int remaining, 761 struct mptcp_out_options *opts) 762 { 763 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 764 765 if (remaining < TCPOLEN_MPTCP_RST) 766 return; 767 768 *size = TCPOLEN_MPTCP_RST; 769 opts->suboptions |= OPTION_MPTCP_RST; 770 opts->reset_transient = subflow->reset_transient; 771 opts->reset_reason = subflow->reset_reason; 772 } 773 774 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, 775 unsigned int *size, unsigned int remaining, 776 struct mptcp_out_options *opts) 777 { 778 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 779 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 780 unsigned int opt_size = 0; 781 bool snd_data_fin; 782 bool ret = false; 783 784 opts->suboptions = 0; 785 786 if (unlikely(__mptcp_check_fallback(msk))) 787 return false; 788 789 if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) { 790 mptcp_established_options_rst(sk, skb, size, remaining, opts); 791 return true; 792 } 793 794 snd_data_fin = mptcp_data_fin_enabled(msk); 795 if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, remaining, opts)) 796 ret = true; 797 else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, remaining, opts)) 798 ret = true; 799 800 /* we reserved enough space for the above options, and exceeding the 801 * TCP option space would be fatal 802 */ 803 if (WARN_ON_ONCE(opt_size > remaining)) 804 return false; 805 806 *size += opt_size; 807 remaining -= opt_size; 808 if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) { 809 *size += opt_size; 810 remaining -= opt_size; 811 ret = true; 812 } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) { 813 *size += opt_size; 814 remaining -= opt_size; 815 ret = true; 816 } 817 818 if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) { 819 *size += opt_size; 820 remaining -= opt_size; 821 ret = true; 822 } 823 824 return ret; 825 } 826 827 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, 828 struct mptcp_out_options *opts) 829 { 830 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 831 832 if (subflow_req->mp_capable) { 833 opts->suboptions = OPTION_MPTCP_MPC_SYNACK; 834 opts->sndr_key = subflow_req->local_key; 835 opts->csum_reqd = subflow_req->csum_reqd; 836 opts->allow_join_id0 = subflow_req->allow_join_id0; 837 *size = TCPOLEN_MPTCP_MPC_SYNACK; 838 pr_debug("subflow_req=%p, local_key=%llu", 839 subflow_req, subflow_req->local_key); 840 return true; 841 } else if (subflow_req->mp_join) { 842 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK; 843 opts->backup = subflow_req->backup; 844 opts->join_id = subflow_req->local_id; 845 opts->thmac = subflow_req->thmac; 846 opts->nonce = subflow_req->local_nonce; 847 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u", 848 subflow_req, opts->backup, opts->join_id, 849 opts->thmac, opts->nonce); 850 *size = TCPOLEN_MPTCP_MPJ_SYNACK; 851 return true; 852 } 853 return false; 854 } 855 856 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 857 struct mptcp_subflow_context *subflow, 858 struct sk_buff *skb, 859 struct mptcp_options_received *mp_opt) 860 { 861 /* here we can process OoO, in-window pkts, only in-sequence 4th ack 862 * will make the subflow fully established 863 */ 864 if (likely(subflow->fully_established)) { 865 /* on passive sockets, check for 3rd ack retransmission 866 * note that msk is always set by subflow_syn_recv_sock() 867 * for mp_join subflows 868 */ 869 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 && 870 TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq && 871 subflow->mp_join && mp_opt->mp_join && 872 READ_ONCE(msk->pm.server_side)) 873 tcp_send_ack(ssk); 874 goto fully_established; 875 } 876 877 /* we must process OoO packets before the first subflow is fully 878 * established. OoO packets are instead a protocol violation 879 * for MP_JOIN subflows as the peer must not send any data 880 * before receiving the forth ack - cfr. RFC 8684 section 3.2. 881 */ 882 if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) { 883 if (subflow->mp_join) 884 goto reset; 885 return subflow->mp_capable; 886 } 887 888 if (mp_opt->dss && mp_opt->use_ack) { 889 /* subflows are fully established as soon as we get any 890 * additional ack. 891 */ 892 subflow->fully_established = 1; 893 WRITE_ONCE(msk->fully_established, true); 894 goto fully_established; 895 } 896 897 if (mp_opt->add_addr) { 898 WRITE_ONCE(msk->fully_established, true); 899 return true; 900 } 901 902 /* If the first established packet does not contain MP_CAPABLE + data 903 * then fallback to TCP. Fallback scenarios requires a reset for 904 * MP_JOIN subflows. 905 */ 906 if (!mp_opt->mp_capable) { 907 if (subflow->mp_join) 908 goto reset; 909 subflow->mp_capable = 0; 910 pr_fallback(msk); 911 __mptcp_do_fallback(msk); 912 return false; 913 } 914 915 if (mp_opt->deny_join_id0) 916 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 917 918 if (unlikely(!READ_ONCE(msk->pm.server_side))) 919 pr_warn_once("bogus mpc option on established client sk"); 920 mptcp_subflow_fully_established(subflow, mp_opt); 921 922 fully_established: 923 /* if the subflow is not already linked into the conn_list, we can't 924 * notify the PM: this subflow is still on the listener queue 925 * and the PM possibly acquiring the subflow lock could race with 926 * the listener close 927 */ 928 if (likely(subflow->pm_notified) || list_empty(&subflow->node)) 929 return true; 930 931 subflow->pm_notified = 1; 932 if (subflow->mp_join) { 933 clear_3rdack_retransmission(ssk); 934 mptcp_pm_subflow_established(msk); 935 } else { 936 mptcp_pm_fully_established(msk, ssk, GFP_ATOMIC); 937 } 938 return true; 939 940 reset: 941 mptcp_subflow_reset(ssk); 942 return false; 943 } 944 945 u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq) 946 { 947 u32 old_seq32, cur_seq32; 948 949 old_seq32 = (u32)old_seq; 950 cur_seq32 = (u32)cur_seq; 951 cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32; 952 if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32))) 953 return cur_seq + (1LL << 32); 954 955 /* reverse wrap could happen, too */ 956 if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32))) 957 return cur_seq - (1LL << 32); 958 return cur_seq; 959 } 960 961 static void ack_update_msk(struct mptcp_sock *msk, 962 struct sock *ssk, 963 struct mptcp_options_received *mp_opt) 964 { 965 u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt); 966 struct sock *sk = (struct sock *)msk; 967 u64 old_snd_una; 968 969 mptcp_data_lock(sk); 970 971 /* avoid ack expansion on update conflict, to reduce the risk of 972 * wrongly expanding to a future ack sequence number, which is way 973 * more dangerous than missing an ack 974 */ 975 old_snd_una = msk->snd_una; 976 new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64); 977 978 /* ACK for data not even sent yet? Ignore. */ 979 if (after64(new_snd_una, snd_nxt)) 980 new_snd_una = old_snd_una; 981 982 new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd; 983 984 if (after64(new_wnd_end, msk->wnd_end)) 985 msk->wnd_end = new_wnd_end; 986 987 /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */ 988 if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt))) 989 __mptcp_check_push(sk, ssk); 990 991 if (after64(new_snd_una, old_snd_una)) { 992 msk->snd_una = new_snd_una; 993 __mptcp_data_acked(sk); 994 } 995 mptcp_data_unlock(sk); 996 997 trace_ack_update_msk(mp_opt->data_ack, 998 old_snd_una, new_snd_una, 999 new_wnd_end, msk->wnd_end); 1000 } 1001 1002 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit) 1003 { 1004 /* Skip if DATA_FIN was already received. 1005 * If updating simultaneously with the recvmsg loop, values 1006 * should match. If they mismatch, the peer is misbehaving and 1007 * we will prefer the most recent information. 1008 */ 1009 if (READ_ONCE(msk->rcv_data_fin)) 1010 return false; 1011 1012 WRITE_ONCE(msk->rcv_data_fin_seq, 1013 mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit)); 1014 WRITE_ONCE(msk->rcv_data_fin, 1); 1015 1016 return true; 1017 } 1018 1019 static bool add_addr_hmac_valid(struct mptcp_sock *msk, 1020 struct mptcp_options_received *mp_opt) 1021 { 1022 u64 hmac = 0; 1023 1024 if (mp_opt->echo) 1025 return true; 1026 1027 hmac = add_addr_generate_hmac(msk->remote_key, 1028 msk->local_key, 1029 &mp_opt->addr); 1030 1031 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n", 1032 msk, (unsigned long long)hmac, 1033 (unsigned long long)mp_opt->ahmac); 1034 1035 return hmac == mp_opt->ahmac; 1036 } 1037 1038 /* Return false if a subflow has been reset, else return true */ 1039 bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 1040 { 1041 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1042 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 1043 struct mptcp_options_received mp_opt; 1044 struct mptcp_ext *mpext; 1045 1046 if (__mptcp_check_fallback(msk)) { 1047 /* Keep it simple and unconditionally trigger send data cleanup and 1048 * pending queue spooling. We will need to acquire the data lock 1049 * for more accurate checks, and once the lock is acquired, such 1050 * helpers are cheap. 1051 */ 1052 mptcp_data_lock(subflow->conn); 1053 if (sk_stream_memory_free(sk)) 1054 __mptcp_check_push(subflow->conn, sk); 1055 __mptcp_data_acked(subflow->conn); 1056 mptcp_data_unlock(subflow->conn); 1057 return true; 1058 } 1059 1060 mptcp_get_options(sk, skb, &mp_opt); 1061 1062 /* The subflow can be in close state only if check_fully_established() 1063 * just sent a reset. If so, tell the caller to ignore the current packet. 1064 */ 1065 if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) 1066 return sk->sk_state != TCP_CLOSE; 1067 1068 if (mp_opt.fastclose && 1069 msk->local_key == mp_opt.rcvr_key) { 1070 WRITE_ONCE(msk->rcv_fastclose, true); 1071 mptcp_schedule_work((struct sock *)msk); 1072 } 1073 1074 if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) { 1075 if (!mp_opt.echo) { 1076 mptcp_pm_add_addr_received(msk, &mp_opt.addr); 1077 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR); 1078 } else { 1079 mptcp_pm_add_addr_echoed(msk, &mp_opt.addr); 1080 mptcp_pm_del_add_timer(msk, &mp_opt.addr, true); 1081 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD); 1082 } 1083 1084 if (mp_opt.addr.port) 1085 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD); 1086 1087 mp_opt.add_addr = 0; 1088 } 1089 1090 if (mp_opt.rm_addr) { 1091 mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list); 1092 mp_opt.rm_addr = 0; 1093 } 1094 1095 if (mp_opt.mp_prio) { 1096 mptcp_pm_mp_prio_received(sk, mp_opt.backup); 1097 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX); 1098 mp_opt.mp_prio = 0; 1099 } 1100 1101 if (mp_opt.reset) { 1102 subflow->reset_seen = 1; 1103 subflow->reset_reason = mp_opt.reset_reason; 1104 subflow->reset_transient = mp_opt.reset_transient; 1105 } 1106 1107 if (!mp_opt.dss) 1108 return true; 1109 1110 /* we can't wait for recvmsg() to update the ack_seq, otherwise 1111 * monodirectional flows will stuck 1112 */ 1113 if (mp_opt.use_ack) 1114 ack_update_msk(msk, sk, &mp_opt); 1115 1116 /* Zero-data-length packets are dropped by the caller and not 1117 * propagated to the MPTCP layer, so the skb extension does not 1118 * need to be allocated or populated. DATA_FIN information, if 1119 * present, needs to be updated here before the skb is freed. 1120 */ 1121 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) { 1122 if (mp_opt.data_fin && mp_opt.data_len == 1 && 1123 mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) && 1124 schedule_work(&msk->work)) 1125 sock_hold(subflow->conn); 1126 1127 return true; 1128 } 1129 1130 mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 1131 if (!mpext) 1132 return true; 1133 1134 memset(mpext, 0, sizeof(*mpext)); 1135 1136 if (mp_opt.use_map) { 1137 if (mp_opt.mpc_map) { 1138 /* this is an MP_CAPABLE carrying MPTCP data 1139 * we know this map the first chunk of data 1140 */ 1141 mptcp_crypto_key_sha(subflow->remote_key, NULL, 1142 &mpext->data_seq); 1143 mpext->data_seq++; 1144 mpext->subflow_seq = 1; 1145 mpext->dsn64 = 1; 1146 mpext->mpc_map = 1; 1147 mpext->data_fin = 0; 1148 } else { 1149 mpext->data_seq = mp_opt.data_seq; 1150 mpext->subflow_seq = mp_opt.subflow_seq; 1151 mpext->dsn64 = mp_opt.dsn64; 1152 mpext->data_fin = mp_opt.data_fin; 1153 } 1154 mpext->data_len = mp_opt.data_len; 1155 mpext->use_map = 1; 1156 mpext->csum_reqd = mp_opt.csum_reqd; 1157 1158 if (mpext->csum_reqd) 1159 mpext->csum = mp_opt.csum; 1160 } 1161 1162 return true; 1163 } 1164 1165 static void mptcp_set_rwin(const struct tcp_sock *tp) 1166 { 1167 const struct sock *ssk = (const struct sock *)tp; 1168 const struct mptcp_subflow_context *subflow; 1169 struct mptcp_sock *msk; 1170 u64 ack_seq; 1171 1172 subflow = mptcp_subflow_ctx(ssk); 1173 msk = mptcp_sk(subflow->conn); 1174 1175 ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd; 1176 1177 if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent))) 1178 WRITE_ONCE(msk->rcv_wnd_sent, ack_seq); 1179 } 1180 1181 static u16 mptcp_make_csum(const struct mptcp_ext *mpext) 1182 { 1183 struct csum_pseudo_header header; 1184 __wsum csum; 1185 1186 /* cfr RFC 8684 3.3.1.: 1187 * the data sequence number used in the pseudo-header is 1188 * always the 64-bit value, irrespective of what length is used in the 1189 * DSS option itself. 1190 */ 1191 header.data_seq = cpu_to_be64(mpext->data_seq); 1192 header.subflow_seq = htonl(mpext->subflow_seq); 1193 header.data_len = htons(mpext->data_len); 1194 header.csum = 0; 1195 1196 csum = csum_partial(&header, sizeof(header), ~csum_unfold(mpext->csum)); 1197 return (__force u16)csum_fold(csum); 1198 } 1199 1200 void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp, 1201 struct mptcp_out_options *opts) 1202 { 1203 if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK | 1204 OPTION_MPTCP_MPC_ACK) & opts->suboptions) { 1205 u8 len, flag = MPTCP_CAP_HMAC_SHA256; 1206 1207 if (OPTION_MPTCP_MPC_SYN & opts->suboptions) { 1208 len = TCPOLEN_MPTCP_MPC_SYN; 1209 } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) { 1210 len = TCPOLEN_MPTCP_MPC_SYNACK; 1211 } else if (opts->ext_copy.data_len) { 1212 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 1213 if (opts->csum_reqd) 1214 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1215 } else { 1216 len = TCPOLEN_MPTCP_MPC_ACK; 1217 } 1218 1219 if (opts->csum_reqd) 1220 flag |= MPTCP_CAP_CHECKSUM_REQD; 1221 1222 if (!opts->allow_join_id0) 1223 flag |= MPTCP_CAP_DENY_JOIN_ID0; 1224 1225 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len, 1226 MPTCP_SUPPORTED_VERSION, 1227 flag); 1228 1229 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) & 1230 opts->suboptions)) 1231 goto mp_capable_done; 1232 1233 put_unaligned_be64(opts->sndr_key, ptr); 1234 ptr += 2; 1235 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions)) 1236 goto mp_capable_done; 1237 1238 put_unaligned_be64(opts->rcvr_key, ptr); 1239 ptr += 2; 1240 if (!opts->ext_copy.data_len) 1241 goto mp_capable_done; 1242 1243 if (opts->csum_reqd) { 1244 put_unaligned_be32(opts->ext_copy.data_len << 16 | 1245 mptcp_make_csum(&opts->ext_copy), ptr); 1246 } else { 1247 put_unaligned_be32(opts->ext_copy.data_len << 16 | 1248 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1249 } 1250 ptr += 1; 1251 } 1252 1253 mp_capable_done: 1254 if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) { 1255 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE; 1256 u8 echo = MPTCP_ADDR_ECHO; 1257 1258 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1259 if (opts->addr.family == AF_INET6) 1260 len = TCPOLEN_MPTCP_ADD_ADDR6_BASE; 1261 #endif 1262 1263 if (opts->addr.port) 1264 len += TCPOLEN_MPTCP_PORT_LEN; 1265 1266 if (opts->ahmac) { 1267 len += sizeof(opts->ahmac); 1268 echo = 0; 1269 } 1270 1271 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR, 1272 len, echo, opts->addr.id); 1273 if (opts->addr.family == AF_INET) { 1274 memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4); 1275 ptr += 1; 1276 } 1277 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1278 else if (opts->addr.family == AF_INET6) { 1279 memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16); 1280 ptr += 4; 1281 } 1282 #endif 1283 1284 if (!opts->addr.port) { 1285 if (opts->ahmac) { 1286 put_unaligned_be64(opts->ahmac, ptr); 1287 ptr += 2; 1288 } 1289 } else { 1290 u16 port = ntohs(opts->addr.port); 1291 1292 if (opts->ahmac) { 1293 u8 *bptr = (u8 *)ptr; 1294 1295 put_unaligned_be16(port, bptr); 1296 bptr += 2; 1297 put_unaligned_be64(opts->ahmac, bptr); 1298 bptr += 8; 1299 put_unaligned_be16(TCPOPT_NOP << 8 | 1300 TCPOPT_NOP, bptr); 1301 1302 ptr += 3; 1303 } else { 1304 put_unaligned_be32(port << 16 | 1305 TCPOPT_NOP << 8 | 1306 TCPOPT_NOP, ptr); 1307 ptr += 1; 1308 } 1309 } 1310 } 1311 1312 if (OPTION_MPTCP_RM_ADDR & opts->suboptions) { 1313 u8 i = 1; 1314 1315 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR, 1316 TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr, 1317 0, opts->rm_list.ids[0]); 1318 1319 while (i < opts->rm_list.nr) { 1320 u8 id1, id2, id3, id4; 1321 1322 id1 = opts->rm_list.ids[i]; 1323 id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP; 1324 id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP; 1325 id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP; 1326 put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr); 1327 ptr += 1; 1328 i += 4; 1329 } 1330 } 1331 1332 if (OPTION_MPTCP_PRIO & opts->suboptions) { 1333 const struct sock *ssk = (const struct sock *)tp; 1334 struct mptcp_subflow_context *subflow; 1335 1336 subflow = mptcp_subflow_ctx(ssk); 1337 subflow->send_mp_prio = 0; 1338 1339 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO, 1340 TCPOLEN_MPTCP_PRIO, 1341 opts->backup, TCPOPT_NOP); 1342 } 1343 1344 if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) { 1345 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1346 TCPOLEN_MPTCP_MPJ_SYN, 1347 opts->backup, opts->join_id); 1348 put_unaligned_be32(opts->token, ptr); 1349 ptr += 1; 1350 put_unaligned_be32(opts->nonce, ptr); 1351 ptr += 1; 1352 } 1353 1354 if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) { 1355 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1356 TCPOLEN_MPTCP_MPJ_SYNACK, 1357 opts->backup, opts->join_id); 1358 put_unaligned_be64(opts->thmac, ptr); 1359 ptr += 2; 1360 put_unaligned_be32(opts->nonce, ptr); 1361 ptr += 1; 1362 } 1363 1364 if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) { 1365 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1366 TCPOLEN_MPTCP_MPJ_ACK, 0, 0); 1367 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN); 1368 ptr += 5; 1369 } 1370 1371 if (OPTION_MPTCP_RST & opts->suboptions) 1372 *ptr++ = mptcp_option(MPTCPOPT_RST, 1373 TCPOLEN_MPTCP_RST, 1374 opts->reset_transient, 1375 opts->reset_reason); 1376 1377 if (opts->ext_copy.use_ack || opts->ext_copy.use_map) { 1378 struct mptcp_ext *mpext = &opts->ext_copy; 1379 u8 len = TCPOLEN_MPTCP_DSS_BASE; 1380 u8 flags = 0; 1381 1382 if (mpext->use_ack) { 1383 flags = MPTCP_DSS_HAS_ACK; 1384 if (mpext->ack64) { 1385 len += TCPOLEN_MPTCP_DSS_ACK64; 1386 flags |= MPTCP_DSS_ACK64; 1387 } else { 1388 len += TCPOLEN_MPTCP_DSS_ACK32; 1389 } 1390 } 1391 1392 if (mpext->use_map) { 1393 len += TCPOLEN_MPTCP_DSS_MAP64; 1394 1395 /* Use only 64-bit mapping flags for now, add 1396 * support for optional 32-bit mappings later. 1397 */ 1398 flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64; 1399 if (mpext->data_fin) 1400 flags |= MPTCP_DSS_DATA_FIN; 1401 1402 if (opts->csum_reqd) 1403 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1404 } 1405 1406 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags); 1407 1408 if (mpext->use_ack) { 1409 if (mpext->ack64) { 1410 put_unaligned_be64(mpext->data_ack, ptr); 1411 ptr += 2; 1412 } else { 1413 put_unaligned_be32(mpext->data_ack32, ptr); 1414 ptr += 1; 1415 } 1416 } 1417 1418 if (mpext->use_map) { 1419 put_unaligned_be64(mpext->data_seq, ptr); 1420 ptr += 2; 1421 put_unaligned_be32(mpext->subflow_seq, ptr); 1422 ptr += 1; 1423 if (opts->csum_reqd) { 1424 put_unaligned_be32(mpext->data_len << 16 | 1425 mptcp_make_csum(mpext), ptr); 1426 } else { 1427 put_unaligned_be32(mpext->data_len << 16 | 1428 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1429 } 1430 } 1431 } 1432 1433 if (tp) 1434 mptcp_set_rwin(tp); 1435 } 1436 1437 __be32 mptcp_get_reset_option(const struct sk_buff *skb) 1438 { 1439 const struct mptcp_ext *ext = mptcp_get_ext(skb); 1440 u8 flags, reason; 1441 1442 if (ext) { 1443 flags = ext->reset_transient; 1444 reason = ext->reset_reason; 1445 1446 return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST, 1447 flags, reason); 1448 } 1449 1450 return htonl(0u); 1451 } 1452 EXPORT_SYMBOL_GPL(mptcp_get_reset_option); 1453