1 // SPDX-License-Identifier: GPL-2.0 2 /* Multipath TCP 3 * 4 * Copyright (c) 2017 - 2019, Intel Corporation. 5 */ 6 7 #define pr_fmt(fmt) "MPTCP: " fmt 8 9 #include <linux/kernel.h> 10 #include <crypto/sha2.h> 11 #include <net/tcp.h> 12 #include <net/mptcp.h> 13 #include "protocol.h" 14 #include "mib.h" 15 16 #include <trace/events/mptcp.h> 17 18 static bool mptcp_cap_flag_sha256(u8 flags) 19 { 20 return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256; 21 } 22 23 static void mptcp_parse_option(const struct sk_buff *skb, 24 const unsigned char *ptr, int opsize, 25 struct mptcp_options_received *mp_opt) 26 { 27 u8 subtype = *ptr >> 4; 28 int expected_opsize; 29 u16 subopt; 30 u8 version; 31 u8 flags; 32 u8 i; 33 34 switch (subtype) { 35 case MPTCPOPT_MP_CAPABLE: 36 /* strict size checking */ 37 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 38 if (skb->len > tcp_hdr(skb)->doff << 2) 39 expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA; 40 else 41 expected_opsize = TCPOLEN_MPTCP_MPC_ACK; 42 subopt = OPTION_MPTCP_MPC_ACK; 43 } else { 44 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK) { 45 expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK; 46 subopt = OPTION_MPTCP_MPC_SYNACK; 47 } else { 48 expected_opsize = TCPOLEN_MPTCP_MPC_SYN; 49 subopt = OPTION_MPTCP_MPC_SYN; 50 } 51 } 52 53 /* Only the MPC + ACK can be used with a RM_ADDR */ 54 if (subopt == OPTION_MPTCP_MPC_ACK) { 55 if ((mp_opt->suboptions & ~OPTION_MPTCP_RM_ADDR) != 0) 56 break; 57 } else if (mp_opt->suboptions != 0) { 58 break; 59 } 60 61 /* Cfr RFC 8684 Section 3.3.0: 62 * If a checksum is present but its use had 63 * not been negotiated in the MP_CAPABLE handshake, the receiver MUST 64 * close the subflow with a RST, as it is not behaving as negotiated. 65 * If a checksum is not present when its use has been negotiated, the 66 * receiver MUST close the subflow with a RST, as it is considered 67 * broken 68 * We parse even option with mismatching csum presence, so that 69 * later in subflow_data_ready we can trigger the reset. 70 */ 71 if (opsize != expected_opsize && 72 (expected_opsize != TCPOLEN_MPTCP_MPC_ACK_DATA || 73 opsize != TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM)) 74 break; 75 76 /* try to be gentle vs future versions on the initial syn */ 77 version = *ptr++ & MPTCP_VERSION_MASK; 78 if (opsize != TCPOLEN_MPTCP_MPC_SYN) { 79 if (version != MPTCP_SUPPORTED_VERSION) 80 break; 81 } else if (version < MPTCP_SUPPORTED_VERSION) { 82 break; 83 } 84 85 flags = *ptr++; 86 if (!mptcp_cap_flag_sha256(flags) || 87 (flags & MPTCP_CAP_EXTENSIBILITY)) 88 break; 89 90 /* RFC 6824, Section 3.1: 91 * "For the Checksum Required bit (labeled "A"), if either 92 * host requires the use of checksums, checksums MUST be used. 93 * In other words, the only way for checksums not to be used 94 * is if both hosts in their SYNs set A=0." 95 */ 96 if (flags & MPTCP_CAP_CHECKSUM_REQD) 97 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 98 99 mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0); 100 101 mp_opt->suboptions |= subopt; 102 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) { 103 mp_opt->sndr_key = get_unaligned_be64(ptr); 104 ptr += 8; 105 } 106 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) { 107 mp_opt->rcvr_key = get_unaligned_be64(ptr); 108 ptr += 8; 109 } 110 if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) { 111 /* Section 3.1.: 112 * "the data parameters in a MP_CAPABLE are semantically 113 * equivalent to those in a DSS option and can be used 114 * interchangeably." 115 */ 116 mp_opt->suboptions |= OPTION_MPTCP_DSS; 117 mp_opt->use_map = 1; 118 mp_opt->mpc_map = 1; 119 mp_opt->data_len = get_unaligned_be16(ptr); 120 ptr += 2; 121 } 122 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) { 123 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 124 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 125 ptr += 2; 126 } 127 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u\n", 128 version, flags, opsize, mp_opt->sndr_key, 129 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum); 130 break; 131 132 case MPTCPOPT_MP_JOIN: 133 /* Can be used with a restricted number of other options */ 134 if ((mp_opt->suboptions & ~(OPTION_MPTCP_RM_ADDR | 135 OPTION_MPTCP_PRIO)) != 0) 136 break; 137 138 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) { 139 mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYN; 140 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 141 mp_opt->join_id = *ptr++; 142 mp_opt->token = get_unaligned_be32(ptr); 143 ptr += 4; 144 mp_opt->nonce = get_unaligned_be32(ptr); 145 ptr += 4; 146 pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u\n", 147 mp_opt->backup, mp_opt->join_id, 148 mp_opt->token, mp_opt->nonce); 149 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) { 150 mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYNACK; 151 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 152 mp_opt->join_id = *ptr++; 153 mp_opt->thmac = get_unaligned_be64(ptr); 154 ptr += 8; 155 mp_opt->nonce = get_unaligned_be32(ptr); 156 ptr += 4; 157 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u\n", 158 mp_opt->backup, mp_opt->join_id, 159 mp_opt->thmac, mp_opt->nonce); 160 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) { 161 mp_opt->suboptions |= OPTION_MPTCP_MPJ_ACK; 162 ptr += 2; 163 memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN); 164 pr_debug("MP_JOIN hmac\n"); 165 } 166 break; 167 168 case MPTCPOPT_DSS: 169 /* Can be used with a restricted number of other options */ 170 if ((mp_opt->suboptions & ~(OPTION_MPTCP_ADD_ADDR | 171 OPTION_MPTCP_RM_ADDR | 172 OPTION_MPTCP_PRIO | 173 OPTION_MPTCP_FASTCLOSE | 174 OPTION_MPTCP_FAIL)) != 0) 175 break; 176 177 pr_debug("DSS\n"); 178 ptr++; 179 180 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK; 181 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0; 182 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0; 183 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0; 184 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK); 185 186 expected_opsize = TCPOLEN_MPTCP_DSS_BASE; 187 188 if (mp_opt->use_ack) { 189 if (mp_opt->ack64) 190 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64; 191 else 192 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32; 193 } 194 195 if (mp_opt->use_map) { 196 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0; 197 if (mp_opt->dsn64) 198 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64; 199 else 200 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32; 201 } 202 203 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d\n", 204 mp_opt->data_fin, mp_opt->dsn64, 205 mp_opt->use_map, mp_opt->ack64, 206 mp_opt->use_ack); 207 208 /* Always parse any csum presence combination, we will enforce 209 * RFC 8684 Section 3.3.0 checks later in subflow_data_ready 210 */ 211 if (opsize != expected_opsize && 212 opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { 213 mp_opt->dsn64 = 0; 214 mp_opt->use_map = 0; 215 mp_opt->ack64 = 0; 216 mp_opt->use_ack = 0; 217 mp_opt->data_fin = 0; 218 break; 219 } 220 221 mp_opt->suboptions |= OPTION_MPTCP_DSS; 222 if (mp_opt->use_ack) { 223 if (mp_opt->ack64) { 224 mp_opt->data_ack = get_unaligned_be64(ptr); 225 ptr += 8; 226 } else { 227 mp_opt->data_ack = get_unaligned_be32(ptr); 228 ptr += 4; 229 } 230 231 pr_debug("data_ack=%llu\n", mp_opt->data_ack); 232 } 233 234 if (mp_opt->use_map) { 235 if (mp_opt->dsn64) { 236 mp_opt->data_seq = get_unaligned_be64(ptr); 237 ptr += 8; 238 } else { 239 mp_opt->data_seq = get_unaligned_be32(ptr); 240 ptr += 4; 241 } 242 243 mp_opt->subflow_seq = get_unaligned_be32(ptr); 244 ptr += 4; 245 246 mp_opt->data_len = get_unaligned_be16(ptr); 247 ptr += 2; 248 249 if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { 250 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 251 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 252 ptr += 2; 253 } 254 255 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n", 256 mp_opt->data_seq, mp_opt->subflow_seq, 257 mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD), 258 mp_opt->csum); 259 } 260 261 break; 262 263 case MPTCPOPT_ADD_ADDR: 264 /* Can be used with a restricted number of other options */ 265 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_DSS | 266 OPTION_MPTCP_RM_ADDR | 267 OPTION_MPTCP_PRIO)) != 0) 268 break; 269 270 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO; 271 if (!mp_opt->echo) { 272 if (opsize == TCPOLEN_MPTCP_ADD_ADDR || 273 opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT) 274 mp_opt->addr.family = AF_INET; 275 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 276 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 || 277 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT) 278 mp_opt->addr.family = AF_INET6; 279 #endif 280 else 281 break; 282 } else { 283 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE || 284 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) 285 mp_opt->addr.family = AF_INET; 286 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 287 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE || 288 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) 289 mp_opt->addr.family = AF_INET6; 290 #endif 291 else 292 break; 293 } 294 295 mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR; 296 mp_opt->addr.id = *ptr++; 297 mp_opt->addr.port = 0; 298 mp_opt->ahmac = 0; 299 if (mp_opt->addr.family == AF_INET) { 300 memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4); 301 ptr += 4; 302 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT || 303 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) { 304 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 305 ptr += 2; 306 } 307 } 308 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 309 else { 310 memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16); 311 ptr += 16; 312 if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT || 313 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) { 314 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 315 ptr += 2; 316 } 317 } 318 #endif 319 if (!mp_opt->echo) { 320 mp_opt->ahmac = get_unaligned_be64(ptr); 321 ptr += 8; 322 } 323 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d\n", 324 (mp_opt->addr.family == AF_INET6) ? "6" : "", 325 mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port)); 326 break; 327 328 case MPTCPOPT_RM_ADDR: 329 /* Can be used with a restricted number of other options */ 330 if ((mp_opt->suboptions & ~(OPTION_MPTCP_MPC_ACK | 331 OPTIONS_MPTCP_MPJ | 332 OPTIONS_MPTCP_DSS | 333 OPTION_MPTCP_ADD_ADDR | 334 OPTION_MPTCP_PRIO)) != 0) 335 break; 336 337 if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 || 338 opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX) 339 break; 340 341 ptr++; 342 343 mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR; 344 mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE; 345 for (i = 0; i < mp_opt->rm_list.nr; i++) 346 mp_opt->rm_list.ids[i] = *ptr++; 347 pr_debug("RM_ADDR: rm_list_nr=%d\n", mp_opt->rm_list.nr); 348 break; 349 350 case MPTCPOPT_MP_PRIO: 351 /* Can be used with a restricted number of other options */ 352 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_MPJ | 353 OPTIONS_MPTCP_DSS | 354 OPTION_MPTCP_ADD_ADDR | 355 OPTION_MPTCP_RM_ADDR)) != 0) 356 break; 357 358 if (opsize != TCPOLEN_MPTCP_PRIO) 359 break; 360 361 mp_opt->suboptions |= OPTION_MPTCP_PRIO; 362 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP; 363 pr_debug("MP_PRIO: prio=%d\n", mp_opt->backup); 364 break; 365 366 case MPTCPOPT_MP_FASTCLOSE: 367 /* Can be used with a restricted number of other options */ 368 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_DSS | 369 OPTION_MPTCP_RST)) != 0) 370 break; 371 372 if (opsize != TCPOLEN_MPTCP_FASTCLOSE) 373 break; 374 375 ptr += 2; 376 mp_opt->rcvr_key = get_unaligned_be64(ptr); 377 ptr += 8; 378 mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE; 379 pr_debug("MP_FASTCLOSE: recv_key=%llu\n", mp_opt->rcvr_key); 380 break; 381 382 case MPTCPOPT_RST: 383 /* Can be used with a restricted number of other options */ 384 if ((mp_opt->suboptions & ~(OPTION_MPTCP_FAIL | 385 OPTION_MPTCP_FASTCLOSE)) != 0) 386 break; 387 388 if (opsize != TCPOLEN_MPTCP_RST) 389 break; 390 391 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) 392 break; 393 394 mp_opt->suboptions |= OPTION_MPTCP_RST; 395 flags = *ptr++; 396 mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT; 397 mp_opt->reset_reason = *ptr; 398 pr_debug("MP_RST: transient=%u reason=%u\n", 399 mp_opt->reset_transient, mp_opt->reset_reason); 400 break; 401 402 case MPTCPOPT_MP_FAIL: 403 /* Can be used with a restricted number of other options */ 404 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_DSS | 405 OPTION_MPTCP_RST)) != 0) 406 break; 407 408 if (opsize != TCPOLEN_MPTCP_FAIL) 409 break; 410 411 ptr += 2; 412 mp_opt->suboptions |= OPTION_MPTCP_FAIL; 413 mp_opt->fail_seq = get_unaligned_be64(ptr); 414 pr_debug("MP_FAIL: data_seq=%llu\n", mp_opt->fail_seq); 415 break; 416 417 default: 418 break; 419 } 420 } 421 422 void mptcp_get_options(const struct sk_buff *skb, 423 struct mptcp_options_received *mp_opt) 424 { 425 const struct tcphdr *th = tcp_hdr(skb); 426 const unsigned char *ptr; 427 int length; 428 429 /* Ensure that casting the whole status to u32 is efficient and safe */ 430 BUILD_BUG_ON(sizeof_field(struct mptcp_options_received, status) != sizeof(u32)); 431 BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct mptcp_options_received, status), 432 sizeof(u32))); 433 *(u32 *)&mp_opt->status = 0; 434 435 length = (th->doff * 4) - sizeof(struct tcphdr); 436 ptr = (const unsigned char *)(th + 1); 437 438 while (length > 0) { 439 int opcode = *ptr++; 440 int opsize; 441 442 switch (opcode) { 443 case TCPOPT_EOL: 444 return; 445 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ 446 length--; 447 continue; 448 default: 449 if (length < 2) 450 return; 451 opsize = *ptr++; 452 if (opsize < 2) /* "silly options" */ 453 return; 454 if (opsize > length) 455 return; /* don't parse partial options */ 456 if (opcode == TCPOPT_MPTCP) 457 mptcp_parse_option(skb, ptr, opsize, mp_opt); 458 ptr += opsize - 2; 459 length -= opsize; 460 } 461 } 462 } 463 464 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb, 465 unsigned int *size, struct mptcp_out_options *opts) 466 { 467 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 468 469 /* we will use snd_isn to detect first pkt [re]transmission 470 * in mptcp_established_options_mp() 471 */ 472 subflow->snd_isn = TCP_SKB_CB(skb)->end_seq; 473 if (subflow->request_mptcp) { 474 if (unlikely(subflow_simultaneous_connect(sk))) { 475 WARN_ON_ONCE(!mptcp_try_fallback(sk, MPTCP_MIB_SIMULTCONNFALLBACK)); 476 477 /* Ensure mptcp_finish_connect() will not process the 478 * MPC handshake. 479 */ 480 subflow->request_mptcp = 0; 481 return false; 482 } 483 484 opts->suboptions = OPTION_MPTCP_MPC_SYN; 485 opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk)); 486 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 487 *size = TCPOLEN_MPTCP_MPC_SYN; 488 return true; 489 } else if (subflow->request_join) { 490 pr_debug("remote_token=%u, nonce=%u\n", subflow->remote_token, 491 subflow->local_nonce); 492 opts->suboptions = OPTION_MPTCP_MPJ_SYN; 493 opts->join_id = subflow->local_id; 494 opts->token = subflow->remote_token; 495 opts->nonce = subflow->local_nonce; 496 opts->backup = subflow->request_bkup; 497 *size = TCPOLEN_MPTCP_MPJ_SYN; 498 return true; 499 } 500 return false; 501 } 502 503 static void clear_3rdack_retransmission(struct sock *sk) 504 { 505 struct inet_connection_sock *icsk = inet_csk(sk); 506 507 sk_stop_timer(sk, &icsk->icsk_delack_timer); 508 icsk->icsk_ack.ato = 0; 509 icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER); 510 } 511 512 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, 513 bool snd_data_fin_enable, int *size, 514 struct mptcp_out_options *opts) 515 { 516 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 517 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 518 struct mptcp_ext *mpext; 519 unsigned int data_len; 520 u8 len; 521 522 /* When skb is not available, we better over-estimate the emitted 523 * options len. A full DSS option (28 bytes) is longer than 524 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so 525 * tell the caller to defer the estimate to 526 * mptcp_established_options_dss(), which will reserve enough space. 527 */ 528 if (!skb) 529 return false; 530 531 /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */ 532 if (READ_ONCE(subflow->fully_established) || snd_data_fin_enable || 533 subflow->snd_isn != TCP_SKB_CB(skb)->seq || 534 sk->sk_state != TCP_ESTABLISHED) 535 return false; 536 537 if (subflow->mp_capable) { 538 mpext = mptcp_get_ext(skb); 539 data_len = mpext ? mpext->data_len : 0; 540 541 /* we will check ops->data_len in mptcp_write_options() to 542 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and 543 * TCPOLEN_MPTCP_MPC_ACK 544 */ 545 opts->data_len = data_len; 546 opts->suboptions = OPTION_MPTCP_MPC_ACK; 547 opts->sndr_key = subflow->local_key; 548 opts->rcvr_key = subflow->remote_key; 549 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 550 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 551 552 /* Section 3.1. 553 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK 554 * packets that start the first subflow of an MPTCP connection, 555 * as well as the first packet that carries data 556 */ 557 if (data_len > 0) { 558 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 559 if (opts->csum_reqd) { 560 /* we need to propagate more info to csum the pseudo hdr */ 561 opts->data_seq = mpext->data_seq; 562 opts->subflow_seq = mpext->subflow_seq; 563 opts->csum = mpext->csum; 564 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 565 } 566 *size = ALIGN(len, 4); 567 } else { 568 *size = TCPOLEN_MPTCP_MPC_ACK; 569 } 570 571 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d\n", 572 subflow, subflow->local_key, subflow->remote_key, 573 data_len); 574 575 return true; 576 } else if (subflow->mp_join) { 577 opts->suboptions = OPTION_MPTCP_MPJ_ACK; 578 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN); 579 *size = TCPOLEN_MPTCP_MPJ_ACK; 580 pr_debug("subflow=%p\n", subflow); 581 582 /* we can use the full delegate action helper only from BH context 583 * If we are in process context - sk is flushing the backlog at 584 * socket lock release time - just set the appropriate flag, will 585 * be handled by the release callback 586 */ 587 if (sock_owned_by_user(sk)) 588 set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status); 589 else 590 mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK); 591 return true; 592 } 593 return false; 594 } 595 596 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow, 597 struct sk_buff *skb, struct mptcp_ext *ext) 598 { 599 /* The write_seq value has already been incremented, so the actual 600 * sequence number for the DATA_FIN is one less. 601 */ 602 u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1; 603 604 if (!ext->use_map || !skb->len) { 605 /* RFC6824 requires a DSS mapping with specific values 606 * if DATA_FIN is set but no data payload is mapped 607 */ 608 ext->data_fin = 1; 609 ext->use_map = 1; 610 ext->dsn64 = 1; 611 ext->data_seq = data_fin_tx_seq; 612 ext->subflow_seq = 0; 613 ext->data_len = 1; 614 } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) { 615 /* If there's an existing DSS mapping and it is the 616 * final mapping, DATA_FIN consumes 1 additional byte of 617 * mapping space. 618 */ 619 ext->data_fin = 1; 620 ext->data_len++; 621 } 622 } 623 624 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, 625 bool snd_data_fin_enable, int *size, 626 struct mptcp_out_options *opts) 627 { 628 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 629 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 630 struct tcp_sock *tp = tcp_sk(sk); 631 unsigned int dss_size = 0; 632 struct mptcp_ext *mpext; 633 unsigned int ack_size; 634 bool ret = false; 635 636 /* Zero `use_ack` and `use_map` flags with one shot. */ 637 memset(&opts->ext_copy.flags, 0, sizeof(opts->ext_copy.flags)); 638 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 639 mpext = skb ? mptcp_get_ext(skb) : NULL; 640 641 if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) { 642 unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64; 643 644 if (mpext) { 645 if (opts->csum_reqd) 646 map_size += TCPOLEN_MPTCP_DSS_CHECKSUM; 647 648 opts->ext_copy = *mpext; 649 } 650 651 dss_size = map_size; 652 if (skb && snd_data_fin_enable) 653 mptcp_write_data_fin(subflow, skb, &opts->ext_copy); 654 opts->suboptions = OPTION_MPTCP_DSS; 655 ret = true; 656 } 657 658 /* passive sockets msk will set the 'can_ack' after accept(), even 659 * if the first subflow may have the already the remote key handy 660 */ 661 if (!READ_ONCE(msk->can_ack)) { 662 *size = ALIGN(dss_size, 4); 663 return ret; 664 } 665 666 if (READ_ONCE(msk->use_64bit_ack)) { 667 ack_size = TCPOLEN_MPTCP_DSS_ACK64; 668 opts->ext_copy.ack64 = 1; 669 } else { 670 ack_size = TCPOLEN_MPTCP_DSS_ACK32; 671 opts->ext_copy.ack64 = 0; 672 } 673 opts->ext_copy.use_ack = 1; 674 opts->suboptions = OPTION_MPTCP_DSS; 675 676 /* Add kind/length/subtype/flag overhead if mapping is not populated */ 677 if (dss_size == 0) 678 ack_size += TCPOLEN_MPTCP_DSS_BASE; 679 680 /* The caller is __tcp_transmit_skb(), and will compute the new rcv 681 * wnd soon: ensure that the window can shrink. 682 */ 683 if (skb) 684 tp->rcv_wnd = tp->rcv_nxt - tp->rcv_wup; 685 686 dss_size += ack_size; 687 688 *size = ALIGN(dss_size, 4); 689 return true; 690 } 691 692 static u64 add_addr_generate_hmac(u64 key1, u64 key2, 693 struct mptcp_addr_info *addr) 694 { 695 u16 port = ntohs(addr->port); 696 u8 hmac[SHA256_DIGEST_SIZE]; 697 u8 msg[19]; 698 int i = 0; 699 700 msg[i++] = addr->id; 701 if (addr->family == AF_INET) { 702 memcpy(&msg[i], &addr->addr.s_addr, 4); 703 i += 4; 704 } 705 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 706 else if (addr->family == AF_INET6) { 707 memcpy(&msg[i], &addr->addr6.s6_addr, 16); 708 i += 16; 709 } 710 #endif 711 msg[i++] = port >> 8; 712 msg[i++] = port & 0xFF; 713 714 mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac); 715 716 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]); 717 } 718 719 static bool mptcp_established_options_add_addr(struct sock *sk, 720 struct sk_buff *skb, int *size, 721 unsigned int remaining, 722 bool has_ts, 723 struct mptcp_out_options *opts) 724 { 725 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 726 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 727 struct mptcp_addr_info addr; 728 bool drop_ts = has_ts; 729 bool echo; 730 731 /* add addr will strip the existing options, be sure to avoid breaking 732 * MPC/MPJ handshakes 733 */ 734 if (!mptcp_pm_should_add_signal(msk) || 735 (opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) || 736 !skb || !skb_is_tcp_pure_ack(skb) || 737 !mptcp_pm_add_addr_signal(msk, size, remaining, &addr, &echo, 738 &drop_ts)) 739 return false; 740 741 pr_debug("drop other suboptions\n"); 742 opts->suboptions = OPTION_MPTCP_ADD_ADDR; 743 opts->drop_ts = drop_ts; 744 opts->addr = addr; 745 if (!echo) { 746 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDRTX); 747 opts->ahmac = add_addr_generate_hmac(READ_ONCE(msk->local_key), 748 READ_ONCE(msk->remote_key), 749 &opts->addr); 750 } else { 751 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADDTX); 752 opts->ahmac = 0; 753 } 754 pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d\n", 755 opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port)); 756 757 return true; 758 } 759 760 static bool mptcp_established_options_rm_addr(struct sock *sk, int *size, 761 unsigned int remaining, 762 struct mptcp_out_options *opts) 763 { 764 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 765 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 766 struct mptcp_rm_list rm_list; 767 int i; 768 769 if (!mptcp_pm_should_rm_signal(msk) || 770 !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list, size))) 771 return false; 772 773 opts->suboptions |= OPTION_MPTCP_RM_ADDR; 774 opts->rm_list = rm_list; 775 776 for (i = 0; i < opts->rm_list.nr; i++) 777 pr_debug("rm_list_ids[%d]=%d\n", i, opts->rm_list.ids[i]); 778 MPTCP_ADD_STATS(sock_net(sk), MPTCP_MIB_RMADDRTX, opts->rm_list.nr); 779 return true; 780 } 781 782 static bool mptcp_established_options_mp_prio(struct sock *sk, int *size, 783 unsigned int remaining, 784 struct mptcp_out_options *opts) 785 { 786 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 787 788 /* can't send MP_PRIO with MPC, as they share the same option space: 789 * 'backup'. Also it makes no sense at all 790 */ 791 if (!subflow->send_mp_prio || (opts->suboptions & OPTIONS_MPTCP_MPC)) 792 return false; 793 794 /* account for the trailing 'nop' option */ 795 if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN) 796 return false; 797 798 *size = TCPOLEN_MPTCP_PRIO_ALIGN; 799 opts->suboptions |= OPTION_MPTCP_PRIO; 800 opts->backup = subflow->request_bkup; 801 802 pr_debug("prio=%d\n", opts->backup); 803 804 return true; 805 } 806 807 static noinline bool mptcp_established_options_rst(struct sock *sk, 808 int *size, 809 unsigned int remaining, 810 struct mptcp_out_options *opts) 811 { 812 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 813 814 if (remaining < TCPOLEN_MPTCP_RST) 815 return false; 816 817 *size = TCPOLEN_MPTCP_RST; 818 opts->suboptions |= OPTION_MPTCP_RST; 819 opts->reset_transient = subflow->reset_transient; 820 opts->reset_reason = subflow->reset_reason; 821 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTTX); 822 823 return true; 824 } 825 826 static bool mptcp_established_options_fastclose(struct sock *sk, int *size, 827 unsigned int remaining, 828 struct mptcp_out_options *opts) 829 { 830 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 831 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 832 833 if (likely(!subflow->send_fastclose)) 834 return false; 835 836 if (remaining < TCPOLEN_MPTCP_FASTCLOSE) 837 return false; 838 839 *size = TCPOLEN_MPTCP_FASTCLOSE; 840 opts->suboptions |= OPTION_MPTCP_FASTCLOSE; 841 opts->rcvr_key = READ_ONCE(msk->remote_key); 842 843 pr_debug("FASTCLOSE key=%llu\n", opts->rcvr_key); 844 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSETX); 845 return true; 846 } 847 848 static bool mptcp_established_options_mp_fail(struct sock *sk, int *size, 849 unsigned int remaining, 850 struct mptcp_out_options *opts) 851 { 852 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 853 854 if (likely(!subflow->send_mp_fail)) 855 return false; 856 857 if (remaining < TCPOLEN_MPTCP_FAIL) 858 return false; 859 860 *size = TCPOLEN_MPTCP_FAIL; 861 opts->suboptions |= OPTION_MPTCP_FAIL; 862 opts->fail_seq = subflow->map_seq; 863 864 pr_debug("MP_FAIL fail_seq=%llu\n", opts->fail_seq); 865 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX); 866 867 return true; 868 } 869 870 int mptcp_established_options(struct sock *sk, struct sk_buff *skb, 871 unsigned int remaining, bool has_ts, 872 struct mptcp_out_options *opts) 873 { 874 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 875 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 876 int total_size = 0; 877 bool snd_data_fin; 878 bool ret = false; 879 int opt_size = 0; 880 881 opts->suboptions = 0; 882 883 /* Force later mptcp_write_options(), but do not use any actual 884 * option space. 885 */ 886 if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb))) 887 return 0; 888 889 if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) { 890 if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) || 891 mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) { 892 total_size += opt_size; 893 remaining -= opt_size; 894 } 895 /* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */ 896 if (mptcp_established_options_rst(sk, &opt_size, remaining, opts)) { 897 total_size += opt_size; 898 remaining -= opt_size; 899 } 900 return total_size; 901 } 902 903 snd_data_fin = mptcp_data_fin_enabled(msk); 904 if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, opts)) 905 ret = true; 906 else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, opts)) { 907 int mp_fail_size; 908 909 ret = true; 910 if (mptcp_established_options_mp_fail(sk, &mp_fail_size, 911 remaining - opt_size, opts)) { 912 total_size += opt_size + mp_fail_size; 913 remaining -= opt_size - mp_fail_size; 914 return total_size; 915 } 916 } 917 918 /* we reserved enough space for the above options, and exceeding the 919 * TCP option space would be fatal 920 */ 921 if (WARN_ON_ONCE(opt_size > remaining)) 922 return -1; 923 924 total_size += opt_size; 925 remaining -= opt_size; 926 if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, 927 has_ts, opts)) { 928 total_size += opt_size; 929 remaining -= opt_size; 930 ret = true; 931 } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) { 932 total_size += opt_size; 933 remaining -= opt_size; 934 ret = true; 935 } 936 937 if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) { 938 total_size += opt_size; 939 remaining -= opt_size; 940 ret = true; 941 } 942 943 return ret ? total_size : -1; 944 } 945 946 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, 947 struct mptcp_out_options *opts) 948 { 949 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 950 951 if (subflow_req->mp_capable) { 952 opts->suboptions = OPTION_MPTCP_MPC_SYNACK; 953 opts->sndr_key = subflow_req->local_key; 954 opts->csum_reqd = subflow_req->csum_reqd; 955 opts->allow_join_id0 = subflow_req->allow_join_id0; 956 *size = TCPOLEN_MPTCP_MPC_SYNACK; 957 pr_debug("subflow_req=%p, local_key=%llu\n", 958 subflow_req, subflow_req->local_key); 959 return true; 960 } else if (subflow_req->mp_join) { 961 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK; 962 opts->backup = subflow_req->request_bkup; 963 opts->join_id = subflow_req->local_id; 964 opts->thmac = subflow_req->thmac; 965 opts->nonce = subflow_req->local_nonce; 966 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u\n", 967 subflow_req, opts->backup, opts->join_id, 968 opts->thmac, opts->nonce); 969 *size = TCPOLEN_MPTCP_MPJ_SYNACK; 970 return true; 971 } 972 return false; 973 } 974 975 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 976 struct mptcp_subflow_context *subflow, 977 struct sk_buff *skb, 978 struct mptcp_options_received *mp_opt) 979 { 980 /* here we can process OoO, in-window pkts, only in-sequence 4th ack 981 * will make the subflow fully established 982 */ 983 if (likely(READ_ONCE(subflow->fully_established))) { 984 /* on passive sockets, check for 3rd ack retransmission 985 * note that msk is always set by subflow_syn_recv_sock() 986 * for mp_join subflows 987 */ 988 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 && 989 TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq && 990 subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) && 991 !subflow->request_join) 992 tcp_send_ack(ssk); 993 goto check_notify; 994 } 995 996 /* we must process OoO packets before the first subflow is fully 997 * established. OoO packets are instead a protocol violation 998 * for MP_JOIN subflows as the peer must not send any data 999 * before receiving the forth ack - cfr. RFC 8684 section 3.2. 1000 */ 1001 if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) { 1002 if (subflow->mp_join) 1003 goto reset; 1004 if (subflow->is_mptfo && mp_opt->suboptions & OPTION_MPTCP_MPC_ACK) 1005 goto set_fully_established; 1006 return subflow->mp_capable; 1007 } 1008 1009 if (subflow->remote_key_valid && 1010 (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) || 1011 ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && 1012 (!mp_opt->echo || subflow->mp_join)))) { 1013 /* subflows are fully established as soon as we get any 1014 * additional ack, including ADD_ADDR. 1015 */ 1016 goto set_fully_established; 1017 } 1018 1019 /* If the first established packet does not contain MP_CAPABLE + data 1020 * then fallback to TCP. Fallback scenarios requires a reset for 1021 * MP_JOIN subflows. 1022 */ 1023 if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) { 1024 if (subflow->mp_join) 1025 goto reset; 1026 subflow->mp_capable = 0; 1027 if (!mptcp_try_fallback(ssk, MPTCP_MIB_MPCAPABLEDATAFALLBACK)) { 1028 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_FALLBACKFAILED); 1029 goto reset; 1030 } 1031 return false; 1032 } 1033 1034 if (unlikely(!READ_ONCE(msk->pm.server_side))) 1035 pr_warn_once("bogus mpc option on established client sk"); 1036 1037 set_fully_established: 1038 if (mp_opt->deny_join_id0) 1039 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 1040 1041 mptcp_data_lock((struct sock *)msk); 1042 __mptcp_subflow_fully_established(msk, subflow, mp_opt); 1043 mptcp_data_unlock((struct sock *)msk); 1044 1045 check_notify: 1046 /* if the subflow is not already linked into the conn_list, we can't 1047 * notify the PM: this subflow is still on the listener queue 1048 * and the PM possibly acquiring the subflow lock could race with 1049 * the listener close 1050 */ 1051 if (likely(subflow->pm_notified) || list_empty(&subflow->node)) 1052 return true; 1053 1054 subflow->pm_notified = 1; 1055 if (subflow->mp_join) { 1056 clear_3rdack_retransmission(ssk); 1057 mptcp_pm_subflow_established(msk); 1058 } else { 1059 mptcp_pm_fully_established(msk, ssk); 1060 } 1061 return true; 1062 1063 reset: 1064 mptcp_subflow_reset(ssk); 1065 return false; 1066 } 1067 1068 u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq) 1069 { 1070 u32 old_seq32, cur_seq32; 1071 1072 old_seq32 = (u32)old_seq; 1073 cur_seq32 = (u32)cur_seq; 1074 cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32; 1075 if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32))) 1076 return cur_seq + (1LL << 32); 1077 1078 /* reverse wrap could happen, too */ 1079 if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32))) 1080 return cur_seq - (1LL << 32); 1081 return cur_seq; 1082 } 1083 1084 static void __mptcp_snd_una_update(struct mptcp_sock *msk, u64 new_snd_una) 1085 { 1086 msk->bytes_acked += new_snd_una - msk->snd_una; 1087 WRITE_ONCE(msk->snd_una, new_snd_una); 1088 } 1089 1090 static void rwin_update(struct mptcp_sock *msk, struct sock *ssk, 1091 struct sk_buff *skb) 1092 { 1093 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1094 struct tcp_sock *tp = tcp_sk(ssk); 1095 u64 mptcp_rcv_wnd; 1096 1097 /* Avoid touching extra cachelines if TCP is going to accept this 1098 * skb without filling the TCP-level window even with a possibly 1099 * outdated mptcp-level rwin. 1100 */ 1101 if (!skb->len || skb->len < tcp_receive_window(tp)) 1102 return; 1103 1104 mptcp_rcv_wnd = atomic64_read(&msk->rcv_wnd_sent); 1105 if (!after64(mptcp_rcv_wnd, subflow->rcv_wnd_sent)) 1106 return; 1107 1108 /* Some other subflow grew the mptcp-level rwin since rcv_wup, 1109 * resync. 1110 */ 1111 tp->rcv_wnd += mptcp_rcv_wnd - subflow->rcv_wnd_sent; 1112 tcp_update_max_rcv_wnd_seq(tp); 1113 subflow->rcv_wnd_sent = mptcp_rcv_wnd; 1114 } 1115 1116 static void ack_update_msk(struct mptcp_sock *msk, 1117 struct sock *ssk, 1118 struct mptcp_options_received *mp_opt) 1119 { 1120 u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt); 1121 struct sock *sk = (struct sock *)msk; 1122 u64 old_snd_una; 1123 1124 mptcp_data_lock(sk); 1125 1126 /* avoid ack expansion on update conflict, to reduce the risk of 1127 * wrongly expanding to a future ack sequence number, which is way 1128 * more dangerous than missing an ack 1129 */ 1130 old_snd_una = msk->snd_una; 1131 new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64); 1132 1133 /* ACK for data not even sent yet? Ignore.*/ 1134 if (unlikely(after64(new_snd_una, snd_nxt))) 1135 new_snd_una = old_snd_una; 1136 1137 new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd; 1138 1139 if (after64(new_wnd_end, msk->wnd_end)) 1140 WRITE_ONCE(msk->wnd_end, new_wnd_end); 1141 1142 /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */ 1143 if (after64(msk->wnd_end, snd_nxt)) 1144 __mptcp_check_push(sk, ssk); 1145 1146 if (after64(new_snd_una, old_snd_una)) { 1147 __mptcp_snd_una_update(msk, new_snd_una); 1148 __mptcp_data_acked(sk); 1149 } 1150 msk->last_ack_recv = tcp_jiffies32; 1151 mptcp_data_unlock(sk); 1152 1153 trace_ack_update_msk(mp_opt->data_ack, 1154 old_snd_una, new_snd_una, 1155 new_wnd_end, READ_ONCE(msk->wnd_end)); 1156 } 1157 1158 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit) 1159 { 1160 /* Skip if DATA_FIN was already received. 1161 * If updating simultaneously with the recvmsg loop, values 1162 * should match. If they mismatch, the peer is misbehaving and 1163 * we will prefer the most recent information. 1164 */ 1165 if (READ_ONCE(msk->rcv_data_fin)) 1166 return false; 1167 1168 WRITE_ONCE(msk->rcv_data_fin_seq, 1169 mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit)); 1170 WRITE_ONCE(msk->rcv_data_fin, 1); 1171 1172 return true; 1173 } 1174 1175 static bool add_addr_hmac_valid(struct mptcp_sock *msk, 1176 struct mptcp_options_received *mp_opt) 1177 { 1178 u64 hmac = 0; 1179 1180 if (mp_opt->echo) 1181 return true; 1182 1183 hmac = add_addr_generate_hmac(READ_ONCE(msk->remote_key), 1184 READ_ONCE(msk->local_key), 1185 &mp_opt->addr); 1186 1187 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n", 1188 msk, hmac, mp_opt->ahmac); 1189 1190 return hmac == mp_opt->ahmac; 1191 } 1192 1193 static bool mptcp_over_limit(struct sock *sk, struct sock *ssk, 1194 const struct sk_buff *skb) 1195 { 1196 struct mptcp_sock *msk = mptcp_sk(sk); 1197 u32 rcvbuf = READ_ONCE(sk->sk_rcvbuf); 1198 1199 if (likely((u32)sk_rmem_alloc_get(sk) <= rcvbuf && 1200 READ_ONCE(msk->backlog_len) <= rcvbuf)) 1201 return false; 1202 1203 /* Avoid silently dropping pure acks, fin, rst or already-acked segm. */ 1204 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || 1205 TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_FIN | TCPHDR_RST) || 1206 !after(TCP_SKB_CB(skb)->end_seq, tcp_sk(ssk)->rcv_nxt)) 1207 return false; 1208 1209 /* Dropped due to memory constraints, schedule an ack. */ 1210 inet_csk(ssk)->icsk_ack.pending |= ICSK_ACK_NOMEM | ICSK_ACK_NOW; 1211 inet_csk_schedule_ack(ssk); 1212 1213 /* Plain TCP (fallback) and skb is dropped before the TCP recv queue. */ 1214 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP); 1215 1216 return true; 1217 } 1218 1219 /* Return false when the caller must drop the packet, i.e. in case of error, 1220 * subflow has been reset, or over memory limits. 1221 */ 1222 bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 1223 { 1224 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1225 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 1226 struct mptcp_options_received mp_opt; 1227 struct mptcp_ext *mpext; 1228 1229 if (__mptcp_check_fallback(msk)) { 1230 /* Keep it simple and unconditionally trigger send data cleanup and 1231 * pending queue spooling. We will need to acquire the data lock 1232 * for more accurate checks, and once the lock is acquired, such 1233 * helpers are cheap. 1234 */ 1235 mptcp_data_lock(subflow->conn); 1236 if (sk_stream_memory_free(sk)) 1237 __mptcp_check_push(subflow->conn, sk); 1238 1239 /* on fallback we just need to ignore the msk-level snd_una, as 1240 * this is really plain TCP 1241 */ 1242 __mptcp_snd_una_update(msk, READ_ONCE(msk->snd_nxt)); 1243 1244 __mptcp_data_acked(subflow->conn); 1245 mptcp_data_unlock(subflow->conn); 1246 return !mptcp_over_limit(subflow->conn, sk, skb); 1247 } 1248 1249 mptcp_get_options(skb, &mp_opt); 1250 1251 /* The subflow can be in close state only if check_fully_established() 1252 * just sent a reset. If so, tell the caller to ignore the current packet. 1253 */ 1254 if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) 1255 return sk->sk_state != TCP_CLOSE; 1256 1257 if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) { 1258 if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) && 1259 READ_ONCE(msk->local_key) == mp_opt.rcvr_key) { 1260 WRITE_ONCE(msk->rcv_fastclose, true); 1261 mptcp_schedule_work((struct sock *)msk); 1262 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX); 1263 } 1264 1265 if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) && 1266 add_addr_hmac_valid(msk, &mp_opt)) { 1267 if (!mp_opt.echo) { 1268 mptcp_pm_add_addr_received(sk, &mp_opt.addr); 1269 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR); 1270 } else { 1271 mptcp_pm_add_addr_echoed(msk, &mp_opt.addr); 1272 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD); 1273 } 1274 1275 if (mp_opt.addr.port) 1276 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD); 1277 } 1278 1279 if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR) 1280 mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list); 1281 1282 if (mp_opt.suboptions & OPTION_MPTCP_PRIO) { 1283 mptcp_pm_mp_prio_received(sk, mp_opt.backup); 1284 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX); 1285 } 1286 1287 if (mp_opt.suboptions & OPTION_MPTCP_FAIL) { 1288 mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq); 1289 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX); 1290 } 1291 1292 if (mp_opt.suboptions & OPTION_MPTCP_RST) { 1293 subflow->reset_seen = 1; 1294 subflow->reset_reason = mp_opt.reset_reason; 1295 subflow->reset_transient = mp_opt.reset_transient; 1296 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTRX); 1297 } 1298 1299 if (!(mp_opt.suboptions & OPTION_MPTCP_DSS)) 1300 return true; 1301 } 1302 1303 /* we can't wait for recvmsg() to update the ack_seq, otherwise 1304 * monodirectional flows will stuck 1305 */ 1306 if (mp_opt.use_ack) 1307 ack_update_msk(msk, sk, &mp_opt); 1308 rwin_update(msk, sk, skb); 1309 1310 /* Zero-data-length packets are dropped by the caller and not 1311 * propagated to the MPTCP layer, so the skb extension does not 1312 * need to be allocated or populated. DATA_FIN information, if 1313 * present, needs to be updated here before the skb is freed. 1314 */ 1315 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) { 1316 if (mp_opt.data_fin && mp_opt.data_len == 1 && 1317 mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64)) 1318 mptcp_schedule_work((struct sock *)msk); 1319 1320 return true; 1321 } 1322 1323 mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 1324 if (!mpext) 1325 return false; 1326 1327 memset(mpext, 0, sizeof(*mpext)); 1328 1329 if (likely(mp_opt.use_map)) { 1330 if (mp_opt.mpc_map) { 1331 /* this is an MP_CAPABLE carrying MPTCP data 1332 * we know this map the first chunk of data 1333 */ 1334 mptcp_crypto_key_sha(subflow->remote_key, NULL, 1335 &mpext->data_seq); 1336 mpext->data_seq++; 1337 mpext->subflow_seq = 1; 1338 mpext->dsn64 = 1; 1339 mpext->mpc_map = 1; 1340 mpext->data_fin = 0; 1341 } else { 1342 mpext->data_seq = mp_opt.data_seq; 1343 mpext->subflow_seq = mp_opt.subflow_seq; 1344 mpext->dsn64 = mp_opt.dsn64; 1345 mpext->data_fin = mp_opt.data_fin; 1346 } 1347 mpext->data_len = mp_opt.data_len; 1348 mpext->use_map = 1; 1349 mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD); 1350 1351 if (mpext->csum_reqd) 1352 mpext->csum = mp_opt.csum; 1353 } 1354 1355 return true; 1356 } 1357 1358 static u64 mptcp_set_rwin(struct mptcp_sock *msk, struct tcp_sock *tp, 1359 struct tcphdr *th, u64 ack_seq) 1360 { 1361 const struct sock *ssk = (const struct sock *)tp; 1362 u64 rcv_wnd_old, rcv_wnd_new; 1363 u32 new_win; 1364 u64 win; 1365 1366 rcv_wnd_new = ack_seq + tp->rcv_wnd; 1367 1368 rcv_wnd_old = atomic64_read(&msk->rcv_wnd_sent); 1369 if (after64(rcv_wnd_new, rcv_wnd_old)) { 1370 u64 rcv_wnd; 1371 1372 for (;;) { 1373 rcv_wnd = atomic64_cmpxchg(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new); 1374 1375 if (rcv_wnd == rcv_wnd_old) 1376 break; 1377 1378 rcv_wnd_old = rcv_wnd; 1379 if (before64(rcv_wnd_new, rcv_wnd_old)) { 1380 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE); 1381 goto raise_win; 1382 } 1383 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT); 1384 } 1385 goto update_wspace; 1386 } 1387 1388 if (rcv_wnd_new != rcv_wnd_old) { 1389 raise_win: 1390 /* The msk-level rcv wnd is after the tcp level one, 1391 * sync the latter. 1392 */ 1393 rcv_wnd_new = rcv_wnd_old; 1394 win = rcv_wnd_old - ack_seq; 1395 new_win = min_t(u64, win, U32_MAX); 1396 tp->rcv_wnd = new_win; 1397 tcp_update_max_rcv_wnd_seq(tp); 1398 1399 /* Make sure we do not exceed the maximum possible 1400 * scaled window. 1401 */ 1402 if (unlikely(th->syn)) 1403 new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale; 1404 if (!tp->rx_opt.rcv_wscale && 1405 READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows)) 1406 new_win = min(new_win, MAX_TCP_WINDOW); 1407 else 1408 new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 1409 1410 /* RFC1323 scaling applied */ 1411 new_win >>= tp->rx_opt.rcv_wscale; 1412 th->window = htons(new_win); 1413 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED); 1414 } 1415 1416 update_wspace: 1417 WRITE_ONCE(msk->old_wspace, tp->rcv_wnd); 1418 return rcv_wnd_new; 1419 } 1420 1421 static void mptcp_track_rwin(struct tcp_sock *tp) 1422 { 1423 const struct sock *ssk = (const struct sock *)tp; 1424 struct mptcp_subflow_context *subflow; 1425 struct mptcp_sock *msk; 1426 1427 if (!ssk) 1428 return; 1429 1430 subflow = mptcp_subflow_ctx(ssk); 1431 msk = mptcp_sk(subflow->conn); 1432 WRITE_ONCE(msk->old_wspace, tp->rcv_wnd); 1433 } 1434 1435 __sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum) 1436 { 1437 struct csum_pseudo_header header; 1438 __wsum csum; 1439 1440 /* cfr RFC 8684 3.3.1.: 1441 * the data sequence number used in the pseudo-header is 1442 * always the 64-bit value, irrespective of what length is used in the 1443 * DSS option itself. 1444 */ 1445 header.data_seq = cpu_to_be64(data_seq); 1446 header.subflow_seq = htonl(subflow_seq); 1447 header.data_len = htons(data_len); 1448 header.csum = 0; 1449 1450 csum = csum_partial(&header, sizeof(header), sum); 1451 return csum_fold(csum); 1452 } 1453 1454 static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext) 1455 { 1456 return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len, 1457 ~csum_unfold(mpext->csum)); 1458 } 1459 1460 static void put_len_csum(u16 len, __sum16 csum, void *data) 1461 { 1462 __sum16 *sumptr = data + 2; 1463 __be16 *ptr = data; 1464 1465 put_unaligned_be16(len, ptr); 1466 1467 put_unaligned(csum, sumptr); 1468 } 1469 1470 void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp, 1471 struct mptcp_out_options *opts) 1472 { 1473 const struct sock *ssk = (const struct sock *)tp; 1474 struct mptcp_subflow_context *subflow; 1475 1476 /* Which options can be used together? 1477 * 1478 * X: mutually exclusive 1479 * O: often used together 1480 * C: can be used together in some cases 1481 * P: could be used together but we prefer not to (optimisations) 1482 * 1483 * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | 1484 * ------|------|------|------|------|------|------|------|------| 1485 * MPC |------|------|------|------|------|------|------|------| 1486 * MPJ | X |------|------|------|------|------|------|------| 1487 * DSS | X | X |------|------|------|------|------|------| 1488 * ADD | X | X | P |------|------|------|------|------| 1489 * RM | C | C | C | P |------|------|------|------| 1490 * PRIO | X | C | C | C | C |------|------|------| 1491 * FAIL | X | X | C | X | X | X |------|------| 1492 * FC | X | X | P | X | X | X | X |------| 1493 * RST | X | X | X | X | X | X | O | O | 1494 * ------|------|------|------|------|------|------|------|------| 1495 * 1496 * The same applies in mptcp_established_options() function. 1497 */ 1498 if (likely(OPTION_MPTCP_DSS & opts->suboptions)) { 1499 struct mptcp_ext *mpext = &opts->ext_copy; 1500 u8 len = TCPOLEN_MPTCP_DSS_BASE; 1501 u8 flags = 0; 1502 1503 if (mpext->use_ack) { 1504 flags = MPTCP_DSS_HAS_ACK; 1505 if (mpext->ack64) { 1506 len += TCPOLEN_MPTCP_DSS_ACK64; 1507 flags |= MPTCP_DSS_ACK64; 1508 } else { 1509 len += TCPOLEN_MPTCP_DSS_ACK32; 1510 } 1511 } 1512 1513 if (mpext->use_map) { 1514 len += TCPOLEN_MPTCP_DSS_MAP64; 1515 1516 /* Use only 64-bit mapping flags for now, add 1517 * support for optional 32-bit mappings later. 1518 */ 1519 flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64; 1520 if (mpext->data_fin) 1521 flags |= MPTCP_DSS_DATA_FIN; 1522 1523 if (opts->csum_reqd) 1524 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1525 } 1526 1527 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags); 1528 1529 if (mpext->use_ack) { 1530 struct mptcp_sock *msk; 1531 u64 ack_seq; 1532 1533 /* DSS option is set only by mptcp_established_options, 1534 * the caller is __tcp_transmit_skb() and ssk is always 1535 * not NULL. 1536 */ 1537 subflow = mptcp_subflow_ctx(ssk); 1538 msk = mptcp_sk(subflow->conn); 1539 ack_seq = READ_ONCE(msk->ack_seq); 1540 if (mpext->ack64) { 1541 put_unaligned_be64(ack_seq, ptr); 1542 ptr += 2; 1543 } else { 1544 put_unaligned_be32(ack_seq, ptr); 1545 ptr += 1; 1546 } 1547 subflow->rcv_wnd_sent = mptcp_set_rwin(msk, tp, th, 1548 ack_seq); 1549 } 1550 1551 if (mpext->use_map) { 1552 put_unaligned_be64(mpext->data_seq, ptr); 1553 ptr += 2; 1554 put_unaligned_be32(mpext->subflow_seq, ptr); 1555 ptr += 1; 1556 if (opts->csum_reqd) { 1557 /* data_len == 0 is reserved for the infinite mapping, 1558 * the checksum will also be set to 0. 1559 */ 1560 put_len_csum(mpext->data_len, 1561 (mpext->data_len ? mptcp_make_csum(mpext) : 0), 1562 ptr); 1563 } else { 1564 put_unaligned_be32(mpext->data_len << 16 | 1565 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1566 } 1567 ptr += 1; 1568 } 1569 1570 /* We might need to add MP_FAIL options in rare cases */ 1571 if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) 1572 goto mp_fail; 1573 } else if (OPTIONS_MPTCP_MPC & opts->suboptions) { 1574 u8 len, flag = MPTCP_CAP_HMAC_SHA256; 1575 1576 if (OPTION_MPTCP_MPC_SYN & opts->suboptions) { 1577 len = TCPOLEN_MPTCP_MPC_SYN; 1578 } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) { 1579 len = TCPOLEN_MPTCP_MPC_SYNACK; 1580 } else if (opts->data_len) { 1581 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 1582 if (opts->csum_reqd) 1583 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1584 } else { 1585 len = TCPOLEN_MPTCP_MPC_ACK; 1586 } 1587 1588 if (opts->csum_reqd) 1589 flag |= MPTCP_CAP_CHECKSUM_REQD; 1590 1591 if (!opts->allow_join_id0) 1592 flag |= MPTCP_CAP_DENY_JOIN_ID0; 1593 1594 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len, 1595 MPTCP_SUPPORTED_VERSION, 1596 flag); 1597 1598 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) & 1599 opts->suboptions)) 1600 goto mp_capable_done; 1601 1602 put_unaligned_be64(opts->sndr_key, ptr); 1603 ptr += 2; 1604 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions)) 1605 goto mp_capable_done; 1606 1607 put_unaligned_be64(opts->rcvr_key, ptr); 1608 ptr += 2; 1609 if (!opts->data_len) 1610 goto mp_capable_done; 1611 1612 if (opts->csum_reqd) { 1613 put_len_csum(opts->data_len, 1614 __mptcp_make_csum(opts->data_seq, 1615 opts->subflow_seq, 1616 opts->data_len, 1617 ~csum_unfold(opts->csum)), 1618 ptr); 1619 } else { 1620 put_unaligned_be32(opts->data_len << 16 | 1621 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1622 } 1623 ptr += 1; 1624 1625 /* MPC is additionally mutually exclusive with MP_PRIO */ 1626 goto mp_capable_done; 1627 } else if (OPTIONS_MPTCP_MPJ & opts->suboptions) { 1628 if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) { 1629 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1630 TCPOLEN_MPTCP_MPJ_SYN, 1631 opts->backup, opts->join_id); 1632 put_unaligned_be32(opts->token, ptr); 1633 ptr += 1; 1634 put_unaligned_be32(opts->nonce, ptr); 1635 ptr += 1; 1636 } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) { 1637 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1638 TCPOLEN_MPTCP_MPJ_SYNACK, 1639 opts->backup, opts->join_id); 1640 put_unaligned_be64(opts->thmac, ptr); 1641 ptr += 2; 1642 put_unaligned_be32(opts->nonce, ptr); 1643 ptr += 1; 1644 } else { 1645 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1646 TCPOLEN_MPTCP_MPJ_ACK, 0, 0); 1647 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN); 1648 ptr += 5; 1649 } 1650 } else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) { 1651 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE; 1652 u8 echo = MPTCP_ADDR_ECHO; 1653 1654 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1655 if (opts->addr.family == AF_INET6) 1656 len = TCPOLEN_MPTCP_ADD_ADDR6_BASE; 1657 #endif 1658 1659 if (opts->addr.port) 1660 len += TCPOLEN_MPTCP_PORT_LEN; 1661 1662 if (opts->ahmac) { 1663 len += sizeof(opts->ahmac); 1664 echo = 0; 1665 } 1666 1667 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR, 1668 len, echo, opts->addr.id); 1669 if (opts->addr.family == AF_INET) { 1670 memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4); 1671 ptr += 1; 1672 } 1673 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1674 else if (opts->addr.family == AF_INET6) { 1675 memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16); 1676 ptr += 4; 1677 } 1678 #endif 1679 1680 if (!opts->addr.port) { 1681 if (opts->ahmac) { 1682 put_unaligned_be64(opts->ahmac, ptr); 1683 ptr += 2; 1684 } 1685 } else { 1686 u16 port = ntohs(opts->addr.port); 1687 1688 if (opts->ahmac) { 1689 u8 *bptr = (u8 *)ptr; 1690 1691 put_unaligned_be16(port, bptr); 1692 bptr += 2; 1693 put_unaligned_be64(opts->ahmac, bptr); 1694 bptr += 8; 1695 put_unaligned_be16(TCPOPT_NOP << 8 | 1696 TCPOPT_NOP, bptr); 1697 1698 ptr += 3; 1699 } else { 1700 put_unaligned_be32(port << 16 | 1701 TCPOPT_NOP << 8 | 1702 TCPOPT_NOP, ptr); 1703 ptr += 1; 1704 } 1705 } 1706 } else if (unlikely(OPTION_MPTCP_FASTCLOSE & opts->suboptions)) { 1707 /* FASTCLOSE is mutually exclusive with others except RST */ 1708 *ptr++ = mptcp_option(MPTCPOPT_MP_FASTCLOSE, 1709 TCPOLEN_MPTCP_FASTCLOSE, 1710 0, 0); 1711 put_unaligned_be64(opts->rcvr_key, ptr); 1712 ptr += 2; 1713 1714 if (OPTION_MPTCP_RST & opts->suboptions) 1715 goto mp_rst; 1716 return; 1717 } else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) { 1718 mp_fail: 1719 /* MP_FAIL is mutually exclusive with others except RST */ 1720 subflow = mptcp_subflow_ctx(ssk); 1721 subflow->send_mp_fail = 0; 1722 1723 *ptr++ = mptcp_option(MPTCPOPT_MP_FAIL, 1724 TCPOLEN_MPTCP_FAIL, 1725 0, 0); 1726 put_unaligned_be64(opts->fail_seq, ptr); 1727 ptr += 2; 1728 1729 if (OPTION_MPTCP_RST & opts->suboptions) 1730 goto mp_rst; 1731 return; 1732 } else if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) { 1733 mp_rst: 1734 *ptr++ = mptcp_option(MPTCPOPT_RST, 1735 TCPOLEN_MPTCP_RST, 1736 opts->reset_transient, 1737 opts->reset_reason); 1738 return; 1739 } else if (unlikely(!opts->suboptions)) { 1740 /* Fallback to TCP */ 1741 mptcp_track_rwin(tp); 1742 return; 1743 } 1744 1745 if (OPTION_MPTCP_PRIO & opts->suboptions) { 1746 subflow = mptcp_subflow_ctx(ssk); 1747 subflow->send_mp_prio = 0; 1748 1749 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO, 1750 TCPOLEN_MPTCP_PRIO, 1751 opts->backup, TCPOPT_NOP); 1752 1753 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPPRIOTX); 1754 } 1755 1756 mp_capable_done: 1757 if (OPTION_MPTCP_RM_ADDR & opts->suboptions) { 1758 u8 i = 1; 1759 1760 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR, 1761 TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr, 1762 0, opts->rm_list.ids[0]); 1763 1764 while (i < opts->rm_list.nr) { 1765 u8 id1, id2, id3, id4; 1766 1767 id1 = opts->rm_list.ids[i]; 1768 id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP; 1769 id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP; 1770 id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP; 1771 put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr); 1772 ptr += 1; 1773 i += 4; 1774 } 1775 } 1776 } 1777 1778 __be32 mptcp_get_reset_option(const struct sk_buff *skb) 1779 { 1780 const struct mptcp_ext *ext = mptcp_get_ext(skb); 1781 u8 flags, reason; 1782 1783 if (ext) { 1784 flags = ext->reset_transient; 1785 reason = ext->reset_reason; 1786 1787 return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST, 1788 flags, reason); 1789 } 1790 1791 return htonl(0u); 1792 } 1793 EXPORT_SYMBOL_GPL(mptcp_get_reset_option); 1794