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 opsize < TCPOLEN_MPTCP_MPC_ACK_DATA) 98 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 99 100 mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0); 101 102 mp_opt->suboptions |= subopt; 103 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) { 104 mp_opt->sndr_key = get_unaligned_be64(ptr); 105 ptr += 8; 106 } 107 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) { 108 mp_opt->rcvr_key = get_unaligned_be64(ptr); 109 ptr += 8; 110 } 111 if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) { 112 /* Section 3.1.: 113 * "the data parameters in a MP_CAPABLE are semantically 114 * equivalent to those in a DSS option and can be used 115 * interchangeably." 116 */ 117 mp_opt->suboptions |= OPTION_MPTCP_DSS; 118 mp_opt->use_map = 1; 119 mp_opt->mpc_map = 1; 120 mp_opt->data_len = get_unaligned_be16(ptr); 121 ptr += 2; 122 } 123 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) { 124 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 125 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 126 ptr += 2; 127 } 128 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u\n", 129 version, flags, opsize, mp_opt->sndr_key, 130 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum); 131 break; 132 133 case MPTCPOPT_MP_JOIN: 134 /* Can be used with a restricted number of other options */ 135 if ((mp_opt->suboptions & ~(OPTION_MPTCP_RM_ADDR | 136 OPTION_MPTCP_PRIO)) != 0) 137 break; 138 139 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) { 140 mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYN; 141 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 142 mp_opt->join_id = *ptr++; 143 mp_opt->token = get_unaligned_be32(ptr); 144 ptr += 4; 145 mp_opt->nonce = get_unaligned_be32(ptr); 146 ptr += 4; 147 pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u\n", 148 mp_opt->backup, mp_opt->join_id, 149 mp_opt->token, mp_opt->nonce); 150 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) { 151 mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYNACK; 152 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 153 mp_opt->join_id = *ptr++; 154 mp_opt->thmac = get_unaligned_be64(ptr); 155 ptr += 8; 156 mp_opt->nonce = get_unaligned_be32(ptr); 157 ptr += 4; 158 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u\n", 159 mp_opt->backup, mp_opt->join_id, 160 mp_opt->thmac, mp_opt->nonce); 161 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) { 162 mp_opt->suboptions |= OPTION_MPTCP_MPJ_ACK; 163 ptr += 2; 164 memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN); 165 pr_debug("MP_JOIN hmac\n"); 166 } 167 break; 168 169 case MPTCPOPT_DSS: 170 /* Can be used with a restricted number of other options */ 171 if ((mp_opt->suboptions & ~(OPTION_MPTCP_ADD_ADDR | 172 OPTION_MPTCP_RM_ADDR | 173 OPTION_MPTCP_PRIO | 174 OPTION_MPTCP_FASTCLOSE | 175 OPTION_MPTCP_FAIL)) != 0) 176 break; 177 178 pr_debug("DSS\n"); 179 ptr++; 180 181 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK; 182 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0; 183 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0; 184 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0; 185 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK); 186 187 expected_opsize = TCPOLEN_MPTCP_DSS_BASE; 188 189 if (mp_opt->use_ack) { 190 if (mp_opt->ack64) 191 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64; 192 else 193 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32; 194 } 195 196 if (mp_opt->use_map) { 197 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0; 198 if (mp_opt->dsn64) 199 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64; 200 else 201 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32; 202 } 203 204 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d\n", 205 mp_opt->data_fin, mp_opt->dsn64, 206 mp_opt->use_map, mp_opt->ack64, 207 mp_opt->use_ack); 208 209 /* Always parse any csum presence combination, we will enforce 210 * RFC 8684 Section 3.3.0 checks later in subflow_data_ready 211 */ 212 if (opsize != expected_opsize && 213 opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { 214 mp_opt->dsn64 = 0; 215 mp_opt->use_map = 0; 216 mp_opt->ack64 = 0; 217 mp_opt->use_ack = 0; 218 mp_opt->data_fin = 0; 219 break; 220 } 221 222 mp_opt->suboptions |= OPTION_MPTCP_DSS; 223 if (mp_opt->use_ack) { 224 if (mp_opt->ack64) { 225 mp_opt->data_ack = get_unaligned_be64(ptr); 226 ptr += 8; 227 } else { 228 mp_opt->data_ack = get_unaligned_be32(ptr); 229 ptr += 4; 230 } 231 232 pr_debug("data_ack=%llu\n", mp_opt->data_ack); 233 } 234 235 if (mp_opt->use_map) { 236 if (mp_opt->dsn64) { 237 mp_opt->data_seq = get_unaligned_be64(ptr); 238 ptr += 8; 239 } else { 240 mp_opt->data_seq = get_unaligned_be32(ptr); 241 ptr += 4; 242 } 243 244 mp_opt->subflow_seq = get_unaligned_be32(ptr); 245 ptr += 4; 246 247 mp_opt->data_len = get_unaligned_be16(ptr); 248 ptr += 2; 249 250 if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { 251 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 252 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 253 ptr += 2; 254 } 255 256 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n", 257 mp_opt->data_seq, mp_opt->subflow_seq, 258 mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD), 259 mp_opt->csum); 260 } 261 262 break; 263 264 case MPTCPOPT_ADD_ADDR: 265 /* Can be used with a restricted number of other options */ 266 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_DSS | 267 OPTION_MPTCP_RM_ADDR | 268 OPTION_MPTCP_PRIO)) != 0) 269 break; 270 271 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO; 272 if (!mp_opt->echo) { 273 if (opsize == TCPOLEN_MPTCP_ADD_ADDR || 274 opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT) 275 mp_opt->addr.family = AF_INET; 276 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 277 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 || 278 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT) 279 mp_opt->addr.family = AF_INET6; 280 #endif 281 else 282 break; 283 } else { 284 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE || 285 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) 286 mp_opt->addr.family = AF_INET; 287 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 288 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE || 289 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) 290 mp_opt->addr.family = AF_INET6; 291 #endif 292 else 293 break; 294 } 295 296 mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR; 297 mp_opt->addr.id = *ptr++; 298 mp_opt->addr.port = 0; 299 mp_opt->ahmac = 0; 300 if (mp_opt->addr.family == AF_INET) { 301 memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4); 302 ptr += 4; 303 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT || 304 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) { 305 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 306 ptr += 2; 307 } 308 } 309 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 310 else { 311 memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16); 312 ptr += 16; 313 if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT || 314 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) { 315 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 316 ptr += 2; 317 } 318 } 319 #endif 320 if (!mp_opt->echo) { 321 mp_opt->ahmac = get_unaligned_be64(ptr); 322 ptr += 8; 323 } 324 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d\n", 325 (mp_opt->addr.family == AF_INET6) ? "6" : "", 326 mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port)); 327 break; 328 329 case MPTCPOPT_RM_ADDR: 330 /* Can be used with a restricted number of other options */ 331 if ((mp_opt->suboptions & ~(OPTION_MPTCP_MPC_ACK | 332 OPTIONS_MPTCP_MPJ | 333 OPTIONS_MPTCP_DSS | 334 OPTION_MPTCP_ADD_ADDR | 335 OPTION_MPTCP_PRIO)) != 0) 336 break; 337 338 if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 || 339 opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX) 340 break; 341 342 ptr++; 343 344 mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR; 345 mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE; 346 for (i = 0; i < mp_opt->rm_list.nr; i++) 347 mp_opt->rm_list.ids[i] = *ptr++; 348 pr_debug("RM_ADDR: rm_list_nr=%d\n", mp_opt->rm_list.nr); 349 break; 350 351 case MPTCPOPT_MP_PRIO: 352 /* Can be used with a restricted number of other options */ 353 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_MPJ | 354 OPTIONS_MPTCP_DSS | 355 OPTION_MPTCP_ADD_ADDR | 356 OPTION_MPTCP_RM_ADDR)) != 0) 357 break; 358 359 if (opsize != TCPOLEN_MPTCP_PRIO) 360 break; 361 362 mp_opt->suboptions |= OPTION_MPTCP_PRIO; 363 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP; 364 pr_debug("MP_PRIO: prio=%d\n", mp_opt->backup); 365 break; 366 367 case MPTCPOPT_MP_FASTCLOSE: 368 /* Can be used with a restricted number of other options */ 369 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_DSS | 370 OPTION_MPTCP_RST)) != 0) 371 break; 372 373 if (opsize != TCPOLEN_MPTCP_FASTCLOSE) 374 break; 375 376 ptr += 2; 377 mp_opt->rcvr_key = get_unaligned_be64(ptr); 378 ptr += 8; 379 mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE; 380 pr_debug("MP_FASTCLOSE: recv_key=%llu\n", mp_opt->rcvr_key); 381 break; 382 383 case MPTCPOPT_RST: 384 /* Can be used with a restricted number of other options */ 385 if ((mp_opt->suboptions & ~(OPTION_MPTCP_FAIL | 386 OPTION_MPTCP_FASTCLOSE)) != 0) 387 break; 388 389 if (opsize != TCPOLEN_MPTCP_RST) 390 break; 391 392 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) 393 break; 394 395 mp_opt->suboptions |= OPTION_MPTCP_RST; 396 flags = *ptr++; 397 mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT; 398 mp_opt->reset_reason = *ptr; 399 pr_debug("MP_RST: transient=%u reason=%u\n", 400 mp_opt->reset_transient, mp_opt->reset_reason); 401 break; 402 403 case MPTCPOPT_MP_FAIL: 404 /* Can be used with a restricted number of other options */ 405 if ((mp_opt->suboptions & ~(OPTIONS_MPTCP_DSS | 406 OPTION_MPTCP_RST)) != 0) 407 break; 408 409 if (opsize != TCPOLEN_MPTCP_FAIL) 410 break; 411 412 ptr += 2; 413 mp_opt->suboptions |= OPTION_MPTCP_FAIL; 414 mp_opt->fail_seq = get_unaligned_be64(ptr); 415 pr_debug("MP_FAIL: data_seq=%llu\n", mp_opt->fail_seq); 416 break; 417 418 default: 419 break; 420 } 421 } 422 423 void mptcp_get_options(const struct sk_buff *skb, 424 struct mptcp_options_received *mp_opt) 425 { 426 const struct tcphdr *th = tcp_hdr(skb); 427 const unsigned char *ptr; 428 int length; 429 430 /* Ensure that casting the whole status to u32 is efficient and safe */ 431 BUILD_BUG_ON(sizeof_field(struct mptcp_options_received, status) != sizeof(u32)); 432 BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct mptcp_options_received, status), 433 sizeof(u32))); 434 *(u32 *)&mp_opt->status = 0; 435 436 length = (th->doff * 4) - sizeof(struct tcphdr); 437 ptr = (const unsigned char *)(th + 1); 438 439 while (length > 0) { 440 int opcode = *ptr++; 441 int opsize; 442 443 switch (opcode) { 444 case TCPOPT_EOL: 445 return; 446 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ 447 length--; 448 continue; 449 default: 450 if (length < 2) 451 return; 452 opsize = *ptr++; 453 if (opsize < 2) /* "silly options" */ 454 return; 455 if (opsize > length) 456 return; /* don't parse partial options */ 457 if (opcode == TCPOPT_MPTCP) 458 mptcp_parse_option(skb, ptr, opsize, mp_opt); 459 ptr += opsize - 2; 460 length -= opsize; 461 } 462 } 463 } 464 465 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb, 466 unsigned int *size, struct mptcp_out_options *opts) 467 { 468 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 469 470 /* we will use snd_isn to detect first pkt [re]transmission 471 * in mptcp_established_options_mp() 472 */ 473 subflow->snd_isn = TCP_SKB_CB(skb)->end_seq; 474 if (subflow->request_mptcp) { 475 if (unlikely(subflow_simultaneous_connect(sk))) { 476 WARN_ON_ONCE(!mptcp_try_fallback(sk, MPTCP_MIB_SIMULTCONNFALLBACK)); 477 478 /* Ensure mptcp_finish_connect() will not process the 479 * MPC handshake. 480 */ 481 subflow->request_mptcp = 0; 482 return false; 483 } 484 485 opts->suboptions = OPTION_MPTCP_MPC_SYN; 486 opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk)); 487 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 488 *size = TCPOLEN_MPTCP_MPC_SYN; 489 return true; 490 } else if (subflow->request_join) { 491 pr_debug("remote_token=%u, nonce=%u\n", subflow->remote_token, 492 subflow->local_nonce); 493 opts->suboptions = OPTION_MPTCP_MPJ_SYN; 494 opts->join_id = subflow->local_id; 495 opts->token = subflow->remote_token; 496 opts->nonce = subflow->local_nonce; 497 opts->backup = subflow->request_bkup; 498 *size = TCPOLEN_MPTCP_MPJ_SYN; 499 return true; 500 } 501 return false; 502 } 503 504 static void clear_3rdack_retransmission(struct sock *sk) 505 { 506 struct inet_connection_sock *icsk = inet_csk(sk); 507 508 sk_stop_timer(sk, &icsk->icsk_delack_timer); 509 icsk->icsk_ack.ato = 0; 510 icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER); 511 } 512 513 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, 514 bool snd_data_fin_enable, int *size, 515 struct mptcp_out_options *opts) 516 { 517 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 518 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 519 struct mptcp_ext *mpext; 520 unsigned int data_len; 521 u8 len; 522 523 /* When skb is not available, we better over-estimate the emitted 524 * options len. A full DSS option (28 bytes) is longer than 525 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so 526 * tell the caller to defer the estimate to 527 * mptcp_established_options_dss(), which will reserve enough space. 528 */ 529 if (!skb) 530 return false; 531 532 /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */ 533 if (subflow->fully_established || snd_data_fin_enable || 534 subflow->snd_isn != TCP_SKB_CB(skb)->seq || 535 sk->sk_state != TCP_ESTABLISHED) 536 return false; 537 538 if (subflow->mp_capable) { 539 mpext = mptcp_get_ext(skb); 540 data_len = mpext ? mpext->data_len : 0; 541 542 /* we will check ops->data_len in mptcp_write_options() to 543 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and 544 * TCPOLEN_MPTCP_MPC_ACK 545 */ 546 opts->data_len = data_len; 547 opts->suboptions = OPTION_MPTCP_MPC_ACK; 548 opts->sndr_key = subflow->local_key; 549 opts->rcvr_key = subflow->remote_key; 550 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 551 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 552 553 /* Section 3.1. 554 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK 555 * packets that start the first subflow of an MPTCP connection, 556 * as well as the first packet that carries data 557 */ 558 if (data_len > 0) { 559 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 560 if (opts->csum_reqd) { 561 /* we need to propagate more info to csum the pseudo hdr */ 562 opts->data_seq = mpext->data_seq; 563 opts->subflow_seq = mpext->subflow_seq; 564 opts->csum = mpext->csum; 565 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 566 } 567 *size = ALIGN(len, 4); 568 } else { 569 *size = TCPOLEN_MPTCP_MPC_ACK; 570 } 571 572 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d\n", 573 subflow, subflow->local_key, subflow->remote_key, 574 data_len); 575 576 return true; 577 } else if (subflow->mp_join) { 578 opts->suboptions = OPTION_MPTCP_MPJ_ACK; 579 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN); 580 *size = TCPOLEN_MPTCP_MPJ_ACK; 581 pr_debug("subflow=%p\n", subflow); 582 583 /* we can use the full delegate action helper only from BH context 584 * If we are in process context - sk is flushing the backlog at 585 * socket lock release time - just set the appropriate flag, will 586 * be handled by the release callback 587 */ 588 if (sock_owned_by_user(sk)) 589 set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status); 590 else 591 mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK); 592 return true; 593 } 594 return false; 595 } 596 597 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow, 598 struct sk_buff *skb, struct mptcp_ext *ext) 599 { 600 /* The write_seq value has already been incremented, so the actual 601 * sequence number for the DATA_FIN is one less. 602 */ 603 u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1; 604 605 if (!ext->use_map || !skb->len) { 606 /* RFC6824 requires a DSS mapping with specific values 607 * if DATA_FIN is set but no data payload is mapped 608 */ 609 ext->data_fin = 1; 610 ext->use_map = 1; 611 ext->dsn64 = 1; 612 ext->data_seq = data_fin_tx_seq; 613 ext->subflow_seq = 0; 614 ext->data_len = 1; 615 ext->csum = 0; 616 } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) { 617 /* If there's an existing DSS mapping and it is the 618 * final mapping, DATA_FIN consumes 1 additional byte of 619 * mapping space. 620 */ 621 ext->data_fin = 1; 622 ext->data_len++; 623 } 624 } 625 626 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, 627 bool snd_data_fin_enable, int *size, 628 struct mptcp_out_options *opts) 629 { 630 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 631 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 632 struct tcp_sock *tp = tcp_sk(sk); 633 unsigned int dss_size = 0; 634 struct mptcp_ext *mpext; 635 unsigned int ack_size; 636 bool ret = false; 637 638 /* Zero `use_ack` and `use_map` flags with one shot. */ 639 memset(&opts->ext_copy.flags, 0, sizeof(opts->ext_copy.flags)); 640 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 641 mpext = skb ? mptcp_get_ext(skb) : NULL; 642 643 if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) { 644 unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64; 645 646 if (mpext) { 647 if (opts->csum_reqd) 648 map_size += TCPOLEN_MPTCP_DSS_CHECKSUM; 649 650 opts->ext_copy = *mpext; 651 } 652 653 dss_size = map_size; 654 if (skb && snd_data_fin_enable) 655 mptcp_write_data_fin(subflow, skb, &opts->ext_copy); 656 opts->suboptions = OPTION_MPTCP_DSS; 657 ret = true; 658 } 659 660 /* passive sockets msk will set the 'can_ack' after accept(), even 661 * if the first subflow may have the already the remote key handy 662 */ 663 if (!READ_ONCE(msk->can_ack)) { 664 *size = ALIGN(dss_size, 4); 665 return ret; 666 } 667 668 if (READ_ONCE(msk->use_64bit_ack)) { 669 ack_size = TCPOLEN_MPTCP_DSS_ACK64; 670 opts->ext_copy.ack64 = 1; 671 } else { 672 ack_size = TCPOLEN_MPTCP_DSS_ACK32; 673 opts->ext_copy.ack64 = 0; 674 } 675 opts->ext_copy.use_ack = 1; 676 opts->suboptions = OPTION_MPTCP_DSS; 677 678 /* Add kind/length/subtype/flag overhead if mapping is not populated */ 679 if (dss_size == 0) 680 ack_size += TCPOLEN_MPTCP_DSS_BASE; 681 682 /* The caller is __tcp_transmit_skb(), and will compute the new rcv 683 * wnd soon: ensure that the window can shrink. 684 */ 685 if (skb) 686 tp->rcv_wnd = tp->rcv_nxt - tp->rcv_wup; 687 688 dss_size += ack_size; 689 690 *size = ALIGN(dss_size, 4); 691 return true; 692 } 693 694 static u64 add_addr_generate_hmac(u64 key1, u64 key2, 695 struct mptcp_addr_info *addr) 696 { 697 u16 port = ntohs(addr->port); 698 u8 hmac[SHA256_DIGEST_SIZE]; 699 u8 msg[19]; 700 int i = 0; 701 702 msg[i++] = addr->id; 703 if (addr->family == AF_INET) { 704 memcpy(&msg[i], &addr->addr.s_addr, 4); 705 i += 4; 706 } 707 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 708 else if (addr->family == AF_INET6) { 709 memcpy(&msg[i], &addr->addr6.s6_addr, 16); 710 i += 16; 711 } 712 #endif 713 msg[i++] = port >> 8; 714 msg[i++] = port & 0xFF; 715 716 mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac); 717 718 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]); 719 } 720 721 static bool mptcp_established_options_add_addr(struct sock *sk, 722 struct sk_buff *skb, int *size, 723 unsigned int remaining, 724 bool has_ts, 725 struct mptcp_out_options *opts) 726 { 727 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 728 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 729 struct mptcp_addr_info addr; 730 bool drop_ts = has_ts; 731 bool echo; 732 733 /* add addr will strip the existing options, be sure to avoid breaking 734 * MPC/MPJ handshakes 735 */ 736 if (!mptcp_pm_should_add_signal(msk) || 737 (opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) || 738 !skb || !skb_is_tcp_pure_ack(skb) || 739 !mptcp_pm_add_addr_signal(msk, size, remaining, &addr, &echo, 740 &drop_ts)) 741 return false; 742 743 pr_debug("drop other suboptions\n"); 744 opts->suboptions = OPTION_MPTCP_ADD_ADDR; 745 opts->drop_ts = drop_ts; 746 opts->addr = addr; 747 if (!echo) { 748 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDRTX); 749 opts->ahmac = add_addr_generate_hmac(READ_ONCE(msk->local_key), 750 READ_ONCE(msk->remote_key), 751 &opts->addr); 752 } else { 753 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADDTX); 754 opts->ahmac = 0; 755 } 756 pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d\n", 757 opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port)); 758 759 return true; 760 } 761 762 static bool mptcp_established_options_rm_addr(struct sock *sk, int *size, 763 unsigned int remaining, 764 struct mptcp_out_options *opts) 765 { 766 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 767 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 768 struct mptcp_rm_list rm_list; 769 int i; 770 771 if (!mptcp_pm_should_rm_signal(msk) || 772 !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list, size))) 773 return false; 774 775 opts->suboptions |= OPTION_MPTCP_RM_ADDR; 776 opts->rm_list = rm_list; 777 778 for (i = 0; i < opts->rm_list.nr; i++) 779 pr_debug("rm_list_ids[%d]=%d\n", i, opts->rm_list.ids[i]); 780 MPTCP_ADD_STATS(sock_net(sk), MPTCP_MIB_RMADDRTX, opts->rm_list.nr); 781 return true; 782 } 783 784 static bool mptcp_established_options_mp_prio(struct sock *sk, int *size, 785 unsigned int remaining, 786 struct mptcp_out_options *opts) 787 { 788 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 789 790 /* can't send MP_PRIO with MPC, as they share the same option space: 791 * 'backup'. Also it makes no sense at all 792 */ 793 if (!subflow->send_mp_prio || (opts->suboptions & OPTIONS_MPTCP_MPC)) 794 return false; 795 796 /* account for the trailing 'nop' option */ 797 if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN) 798 return false; 799 800 *size = TCPOLEN_MPTCP_PRIO_ALIGN; 801 opts->suboptions |= OPTION_MPTCP_PRIO; 802 opts->backup = subflow->request_bkup; 803 804 pr_debug("prio=%d\n", opts->backup); 805 806 return true; 807 } 808 809 static noinline bool mptcp_established_options_rst(struct sock *sk, 810 int *size, 811 unsigned int remaining, 812 struct mptcp_out_options *opts) 813 { 814 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 815 816 if (remaining < TCPOLEN_MPTCP_RST) 817 return false; 818 819 *size = TCPOLEN_MPTCP_RST; 820 opts->suboptions |= OPTION_MPTCP_RST; 821 opts->reset_transient = subflow->reset_transient; 822 opts->reset_reason = subflow->reset_reason; 823 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTTX); 824 825 return true; 826 } 827 828 static bool mptcp_established_options_fastclose(struct sock *sk, int *size, 829 unsigned int remaining, 830 struct mptcp_out_options *opts) 831 { 832 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 833 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 834 835 if (likely(!subflow->send_fastclose)) 836 return false; 837 838 if (remaining < TCPOLEN_MPTCP_FASTCLOSE) 839 return false; 840 841 *size = TCPOLEN_MPTCP_FASTCLOSE; 842 opts->suboptions |= OPTION_MPTCP_FASTCLOSE; 843 opts->rcvr_key = READ_ONCE(msk->remote_key); 844 845 pr_debug("FASTCLOSE key=%llu\n", opts->rcvr_key); 846 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSETX); 847 return true; 848 } 849 850 static bool mptcp_established_options_mp_fail(struct sock *sk, int *size, 851 unsigned int remaining, 852 struct mptcp_out_options *opts) 853 { 854 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 855 856 if (likely(!subflow->send_mp_fail)) 857 return false; 858 859 if (remaining < TCPOLEN_MPTCP_FAIL) 860 return false; 861 862 *size = TCPOLEN_MPTCP_FAIL; 863 opts->suboptions |= OPTION_MPTCP_FAIL; 864 opts->fail_seq = subflow->map_seq; 865 866 pr_debug("MP_FAIL fail_seq=%llu\n", opts->fail_seq); 867 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX); 868 869 return true; 870 } 871 872 int mptcp_established_options(struct sock *sk, struct sk_buff *skb, 873 unsigned int remaining, bool has_ts, 874 struct mptcp_out_options *opts) 875 { 876 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 877 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 878 int total_size = 0; 879 bool snd_data_fin; 880 bool ret = false; 881 int opt_size = 0; 882 883 opts->suboptions = 0; 884 885 /* Force later mptcp_write_options(), but do not use any actual 886 * option space. 887 */ 888 if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb))) 889 return 0; 890 891 if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) { 892 if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) || 893 mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) { 894 total_size += opt_size; 895 remaining -= opt_size; 896 } 897 /* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */ 898 if (mptcp_established_options_rst(sk, &opt_size, remaining, opts)) { 899 total_size += opt_size; 900 remaining -= opt_size; 901 } 902 return total_size; 903 } 904 905 snd_data_fin = mptcp_data_fin_enabled(msk); 906 if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, opts)) 907 ret = true; 908 else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, opts)) { 909 int mp_fail_size; 910 911 ret = true; 912 if (mptcp_established_options_mp_fail(sk, &mp_fail_size, 913 remaining - opt_size, opts)) { 914 total_size += opt_size + mp_fail_size; 915 remaining -= opt_size - mp_fail_size; 916 return total_size; 917 } 918 } 919 920 /* we reserved enough space for the above options, and exceeding the 921 * TCP option space would be fatal 922 */ 923 if (WARN_ON_ONCE(opt_size > remaining)) 924 return -1; 925 926 total_size += opt_size; 927 remaining -= opt_size; 928 if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, 929 has_ts, opts)) { 930 total_size += opt_size; 931 remaining -= opt_size; 932 ret = true; 933 } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) { 934 total_size += opt_size; 935 remaining -= opt_size; 936 ret = true; 937 } 938 939 if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) { 940 total_size += opt_size; 941 remaining -= opt_size; 942 ret = true; 943 } 944 945 return ret ? total_size : -1; 946 } 947 948 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, 949 struct mptcp_out_options *opts) 950 { 951 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 952 953 if (subflow_req->mp_capable) { 954 opts->suboptions = OPTION_MPTCP_MPC_SYNACK; 955 opts->sndr_key = subflow_req->local_key; 956 opts->csum_reqd = subflow_req->csum_reqd; 957 opts->allow_join_id0 = subflow_req->allow_join_id0; 958 *size = TCPOLEN_MPTCP_MPC_SYNACK; 959 pr_debug("subflow_req=%p, local_key=%llu\n", 960 subflow_req, subflow_req->local_key); 961 return true; 962 } else if (subflow_req->mp_join) { 963 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK; 964 opts->backup = subflow_req->request_bkup; 965 opts->join_id = subflow_req->local_id; 966 opts->thmac = subflow_req->thmac; 967 opts->nonce = subflow_req->local_nonce; 968 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u\n", 969 subflow_req, opts->backup, opts->join_id, 970 opts->thmac, opts->nonce); 971 *size = TCPOLEN_MPTCP_MPJ_SYNACK; 972 return true; 973 } 974 return false; 975 } 976 977 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 978 struct mptcp_subflow_context *subflow, 979 struct sk_buff *skb, 980 struct mptcp_options_received *mp_opt) 981 { 982 /* here we can process OoO, in-window pkts, only in-sequence 4th ack 983 * will make the subflow fully established 984 */ 985 if (likely(subflow->fully_established)) { 986 /* on passive sockets, check for 3rd ack retransmission 987 * note that msk is always set by subflow_syn_recv_sock() 988 * for mp_join subflows 989 */ 990 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 && 991 TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq && 992 subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) && 993 !subflow->request_join) 994 tcp_send_ack(ssk); 995 goto check_notify; 996 } 997 998 /* we must process OoO packets before the first subflow is fully 999 * established. OoO packets are instead a protocol violation 1000 * for MP_JOIN subflows as the peer must not send any data 1001 * before receiving the forth ack - cfr. RFC 8684 section 3.2. 1002 */ 1003 if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) { 1004 if (subflow->mp_join) 1005 goto reset; 1006 if (subflow->is_mptfo && mp_opt->suboptions & OPTION_MPTCP_MPC_ACK) 1007 goto set_fully_established; 1008 return subflow->mp_capable; 1009 } 1010 1011 if (subflow->remote_key_valid && 1012 (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) || 1013 ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && 1014 (!mp_opt->echo || subflow->mp_join)))) { 1015 /* subflows are fully established as soon as we get any 1016 * additional ack, including ADD_ADDR. 1017 */ 1018 goto set_fully_established; 1019 } 1020 1021 /* If the first established packet does not contain MP_CAPABLE + data 1022 * then fallback to TCP. Fallback scenarios requires a reset for 1023 * MP_JOIN subflows. 1024 */ 1025 if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) { 1026 if (subflow->mp_join) 1027 goto reset; 1028 subflow->mp_capable = 0; 1029 if (!mptcp_try_fallback(ssk, MPTCP_MIB_MPCAPABLEDATAFALLBACK)) { 1030 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_FALLBACKFAILED); 1031 goto reset; 1032 } 1033 return false; 1034 } 1035 1036 if (unlikely(!READ_ONCE(msk->pm.server_side))) 1037 pr_warn_once("bogus mpc option on established client sk"); 1038 1039 set_fully_established: 1040 if (mp_opt->deny_join_id0) 1041 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 1042 1043 mptcp_data_lock((struct sock *)msk); 1044 __mptcp_subflow_fully_established(msk, subflow, mp_opt); 1045 mptcp_data_unlock((struct sock *)msk); 1046 1047 check_notify: 1048 /* if the subflow is not already linked into the conn_list, we can't 1049 * notify the PM: this subflow is still on the listener queue 1050 * and the PM possibly acquiring the subflow lock could race with 1051 * the listener close 1052 */ 1053 if (likely(subflow->pm_notified) || list_empty(&subflow->node)) 1054 return true; 1055 1056 subflow->pm_notified = 1; 1057 if (subflow->mp_join) { 1058 clear_3rdack_retransmission(ssk); 1059 mptcp_pm_subflow_established(msk); 1060 } else { 1061 mptcp_pm_fully_established(msk, ssk); 1062 } 1063 return true; 1064 1065 reset: 1066 mptcp_subflow_reset(ssk); 1067 return false; 1068 } 1069 1070 u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq) 1071 { 1072 u32 old_seq32, cur_seq32; 1073 1074 old_seq32 = (u32)old_seq; 1075 cur_seq32 = (u32)cur_seq; 1076 cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32; 1077 if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32))) 1078 return cur_seq + (1LL << 32); 1079 1080 /* reverse wrap could happen, too */ 1081 if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32))) 1082 return cur_seq - (1LL << 32); 1083 return cur_seq; 1084 } 1085 1086 static void __mptcp_snd_una_update(struct mptcp_sock *msk, u64 new_snd_una) 1087 { 1088 msk->bytes_acked += new_snd_una - msk->snd_una; 1089 WRITE_ONCE(msk->snd_una, new_snd_una); 1090 } 1091 1092 static void rwin_update(struct mptcp_sock *msk, struct sock *ssk, 1093 struct sk_buff *skb) 1094 { 1095 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); 1096 struct tcp_sock *tp = tcp_sk(ssk); 1097 u64 mptcp_rcv_wnd; 1098 1099 /* Avoid touching extra cachelines if TCP is going to accept this 1100 * skb without filling the TCP-level window even with a possibly 1101 * outdated mptcp-level rwin. 1102 */ 1103 if (!skb->len || skb->len < tcp_receive_window(tp)) 1104 return; 1105 1106 mptcp_rcv_wnd = atomic64_read(&msk->rcv_wnd_sent); 1107 if (!after64(mptcp_rcv_wnd, subflow->rcv_wnd_sent)) 1108 return; 1109 1110 /* Some other subflow grew the mptcp-level rwin since rcv_wup, 1111 * resync. 1112 */ 1113 tp->rcv_wnd += mptcp_rcv_wnd - subflow->rcv_wnd_sent; 1114 tcp_update_max_rcv_wnd_seq(tp); 1115 subflow->rcv_wnd_sent = mptcp_rcv_wnd; 1116 } 1117 1118 static void ack_update_msk(struct mptcp_sock *msk, 1119 struct sock *ssk, 1120 struct mptcp_options_received *mp_opt) 1121 { 1122 u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt); 1123 struct sock *sk = (struct sock *)msk; 1124 u64 old_snd_una; 1125 1126 mptcp_data_lock(sk); 1127 1128 /* avoid ack expansion on update conflict, to reduce the risk of 1129 * wrongly expanding to a future ack sequence number, which is way 1130 * more dangerous than missing an ack 1131 */ 1132 old_snd_una = msk->snd_una; 1133 new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64); 1134 1135 /* ACK for data not even sent yet? Ignore.*/ 1136 if (unlikely(after64(new_snd_una, snd_nxt))) 1137 new_snd_una = old_snd_una; 1138 1139 new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd; 1140 1141 if (after64(new_wnd_end, msk->wnd_end)) 1142 WRITE_ONCE(msk->wnd_end, new_wnd_end); 1143 1144 /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */ 1145 if (after64(msk->wnd_end, snd_nxt)) 1146 __mptcp_check_push(sk, ssk); 1147 1148 if (after64(new_snd_una, old_snd_una)) { 1149 __mptcp_snd_una_update(msk, new_snd_una); 1150 __mptcp_data_acked(sk); 1151 } 1152 msk->last_ack_recv = tcp_jiffies32; 1153 mptcp_data_unlock(sk); 1154 1155 trace_ack_update_msk(mp_opt->data_ack, 1156 old_snd_una, new_snd_una, 1157 new_wnd_end, READ_ONCE(msk->wnd_end)); 1158 } 1159 1160 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit) 1161 { 1162 /* Skip if DATA_FIN was already received. 1163 * If updating simultaneously with the recvmsg loop, values 1164 * should match. If they mismatch, the peer is misbehaving and 1165 * we will prefer the most recent information. 1166 */ 1167 if (READ_ONCE(msk->rcv_data_fin)) 1168 return false; 1169 1170 WRITE_ONCE(msk->rcv_data_fin_seq, 1171 mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit)); 1172 WRITE_ONCE(msk->rcv_data_fin, 1); 1173 1174 return true; 1175 } 1176 1177 static bool add_addr_hmac_valid(struct mptcp_sock *msk, 1178 struct mptcp_options_received *mp_opt) 1179 { 1180 u64 hmac = 0; 1181 1182 if (mp_opt->echo) 1183 return true; 1184 1185 hmac = add_addr_generate_hmac(READ_ONCE(msk->remote_key), 1186 READ_ONCE(msk->local_key), 1187 &mp_opt->addr); 1188 1189 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n", 1190 msk, hmac, mp_opt->ahmac); 1191 1192 return hmac == mp_opt->ahmac; 1193 } 1194 1195 static bool mptcp_over_limit(struct sock *sk, struct sock *ssk, 1196 const struct sk_buff *skb) 1197 { 1198 struct mptcp_sock *msk = mptcp_sk(sk); 1199 u32 rcvbuf = READ_ONCE(sk->sk_rcvbuf); 1200 1201 if (likely((u32)sk_rmem_alloc_get(sk) <= rcvbuf && 1202 READ_ONCE(msk->backlog_len) <= rcvbuf)) 1203 return false; 1204 1205 /* Avoid silently dropping pure acks, fin, rst or already-acked segm. */ 1206 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || 1207 TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_FIN | TCPHDR_RST) || 1208 !after(TCP_SKB_CB(skb)->end_seq, tcp_sk(ssk)->rcv_nxt)) 1209 return false; 1210 1211 /* Dropped due to memory constraints, schedule an ack. */ 1212 inet_csk(ssk)->icsk_ack.pending |= ICSK_ACK_NOMEM | ICSK_ACK_NOW; 1213 inet_csk_schedule_ack(ssk); 1214 1215 /* Plain TCP (fallback) and skb is dropped before the TCP recv queue. */ 1216 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP); 1217 1218 return true; 1219 } 1220 1221 /* Return false when the caller must drop the packet, i.e. in case of error, 1222 * subflow has been reset, or over memory limits. 1223 */ 1224 bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 1225 { 1226 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1227 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 1228 struct mptcp_options_received mp_opt; 1229 struct mptcp_ext *mpext; 1230 1231 if (__mptcp_check_fallback(msk)) { 1232 /* Keep it simple and unconditionally trigger send data cleanup and 1233 * pending queue spooling. We will need to acquire the data lock 1234 * for more accurate checks, and once the lock is acquired, such 1235 * helpers are cheap. 1236 */ 1237 mptcp_data_lock(subflow->conn); 1238 if (sk_stream_memory_free(sk)) 1239 __mptcp_check_push(subflow->conn, sk); 1240 1241 /* on fallback we just need to ignore the msk-level snd_una, as 1242 * this is really plain TCP 1243 */ 1244 __mptcp_snd_una_update(msk, READ_ONCE(msk->snd_nxt)); 1245 1246 __mptcp_data_acked(subflow->conn); 1247 mptcp_data_unlock(subflow->conn); 1248 return !mptcp_over_limit(subflow->conn, sk, skb); 1249 } 1250 1251 mptcp_get_options(skb, &mp_opt); 1252 1253 /* The subflow can be in close state only if check_fully_established() 1254 * just sent a reset. If so, tell the caller to ignore the current packet. 1255 */ 1256 if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) 1257 return sk->sk_state != TCP_CLOSE; 1258 1259 if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) { 1260 if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) && 1261 READ_ONCE(msk->local_key) == mp_opt.rcvr_key) { 1262 WRITE_ONCE(msk->rcv_fastclose, true); 1263 mptcp_schedule_work((struct sock *)msk); 1264 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX); 1265 } 1266 1267 if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) && 1268 add_addr_hmac_valid(msk, &mp_opt)) { 1269 if (!mp_opt.echo) { 1270 mptcp_pm_add_addr_received(sk, &mp_opt.addr); 1271 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR); 1272 } else { 1273 mptcp_pm_add_addr_echoed(msk, &mp_opt.addr); 1274 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD); 1275 } 1276 1277 if (mp_opt.addr.port) 1278 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD); 1279 } 1280 1281 if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR) 1282 mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list); 1283 1284 if (mp_opt.suboptions & OPTION_MPTCP_PRIO) { 1285 mptcp_pm_mp_prio_received(sk, mp_opt.backup); 1286 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX); 1287 } 1288 1289 if (mp_opt.suboptions & OPTION_MPTCP_FAIL) { 1290 mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq); 1291 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX); 1292 } 1293 1294 if (mp_opt.suboptions & OPTION_MPTCP_RST) { 1295 subflow->reset_seen = 1; 1296 subflow->reset_reason = mp_opt.reset_reason; 1297 subflow->reset_transient = mp_opt.reset_transient; 1298 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTRX); 1299 } 1300 1301 if (!(mp_opt.suboptions & OPTION_MPTCP_DSS)) 1302 return true; 1303 } 1304 1305 /* we can't wait for recvmsg() to update the ack_seq, otherwise 1306 * monodirectional flows will stuck 1307 */ 1308 if (mp_opt.use_ack) 1309 ack_update_msk(msk, sk, &mp_opt); 1310 rwin_update(msk, sk, skb); 1311 1312 /* Zero-data-length packets are dropped by the caller and not 1313 * propagated to the MPTCP layer, so the skb extension does not 1314 * need to be allocated or populated. DATA_FIN information, if 1315 * present, needs to be updated here before the skb is freed. 1316 */ 1317 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) { 1318 if (mp_opt.data_fin && mp_opt.data_len == 1 && 1319 mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64)) 1320 mptcp_schedule_work((struct sock *)msk); 1321 1322 return true; 1323 } 1324 1325 mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 1326 if (!mpext) 1327 return false; 1328 1329 memset(mpext, 0, sizeof(*mpext)); 1330 1331 if (likely(mp_opt.use_map)) { 1332 if (mp_opt.mpc_map) { 1333 /* this is an MP_CAPABLE carrying MPTCP data 1334 * we know this map the first chunk of data 1335 */ 1336 mptcp_crypto_key_sha(subflow->remote_key, NULL, 1337 &mpext->data_seq); 1338 mpext->data_seq++; 1339 mpext->subflow_seq = 1; 1340 mpext->dsn64 = 1; 1341 mpext->mpc_map = 1; 1342 mpext->data_fin = 0; 1343 } else { 1344 mpext->data_seq = mp_opt.data_seq; 1345 mpext->subflow_seq = mp_opt.subflow_seq; 1346 mpext->dsn64 = mp_opt.dsn64; 1347 mpext->data_fin = mp_opt.data_fin; 1348 } 1349 mpext->data_len = mp_opt.data_len; 1350 mpext->use_map = 1; 1351 mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD); 1352 1353 if (mpext->csum_reqd) 1354 mpext->csum = mp_opt.csum; 1355 } 1356 1357 return true; 1358 } 1359 1360 static u64 mptcp_set_rwin(struct mptcp_sock *msk, struct tcp_sock *tp, 1361 struct tcphdr *th, u64 ack_seq) 1362 { 1363 const struct sock *ssk = (const struct sock *)tp; 1364 u64 rcv_wnd_old, rcv_wnd_new; 1365 u32 new_win; 1366 u64 win; 1367 1368 rcv_wnd_new = ack_seq + tp->rcv_wnd; 1369 1370 rcv_wnd_old = atomic64_read(&msk->rcv_wnd_sent); 1371 if (after64(rcv_wnd_new, rcv_wnd_old)) { 1372 u64 rcv_wnd; 1373 1374 for (;;) { 1375 rcv_wnd = atomic64_cmpxchg(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new); 1376 1377 if (rcv_wnd == rcv_wnd_old) 1378 break; 1379 1380 rcv_wnd_old = rcv_wnd; 1381 if (before64(rcv_wnd_new, rcv_wnd_old)) { 1382 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE); 1383 goto raise_win; 1384 } 1385 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT); 1386 } 1387 goto update_wspace; 1388 } 1389 1390 if (rcv_wnd_new != rcv_wnd_old) { 1391 raise_win: 1392 /* The msk-level rcv wnd is after the tcp level one, 1393 * sync the latter. 1394 */ 1395 rcv_wnd_new = rcv_wnd_old; 1396 win = rcv_wnd_old - ack_seq; 1397 new_win = min_t(u64, win, U32_MAX); 1398 tp->rcv_wnd = new_win; 1399 tcp_update_max_rcv_wnd_seq(tp); 1400 1401 /* Make sure we do not exceed the maximum possible 1402 * scaled window. 1403 */ 1404 if (unlikely(th->syn)) 1405 new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale; 1406 if (!tp->rx_opt.rcv_wscale && 1407 READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows)) 1408 new_win = min(new_win, MAX_TCP_WINDOW); 1409 else 1410 new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 1411 1412 /* RFC1323 scaling applied */ 1413 new_win >>= tp->rx_opt.rcv_wscale; 1414 th->window = htons(new_win); 1415 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED); 1416 } 1417 1418 update_wspace: 1419 WRITE_ONCE(msk->old_wspace, tp->rcv_wnd); 1420 return rcv_wnd_new; 1421 } 1422 1423 static void mptcp_track_rwin(struct tcp_sock *tp) 1424 { 1425 const struct sock *ssk = (const struct sock *)tp; 1426 struct mptcp_subflow_context *subflow; 1427 struct mptcp_sock *msk; 1428 1429 if (!ssk) 1430 return; 1431 1432 subflow = mptcp_subflow_ctx(ssk); 1433 msk = mptcp_sk(subflow->conn); 1434 WRITE_ONCE(msk->old_wspace, tp->rcv_wnd); 1435 } 1436 1437 __sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum) 1438 { 1439 struct csum_pseudo_header header; 1440 __wsum csum; 1441 1442 /* cfr RFC 8684 3.3.1.: 1443 * the data sequence number used in the pseudo-header is 1444 * always the 64-bit value, irrespective of what length is used in the 1445 * DSS option itself. 1446 */ 1447 header.data_seq = cpu_to_be64(data_seq); 1448 header.subflow_seq = htonl(subflow_seq); 1449 header.data_len = htons(data_len); 1450 header.csum = 0; 1451 1452 csum = csum_partial(&header, sizeof(header), sum); 1453 return csum_fold(csum); 1454 } 1455 1456 static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext) 1457 { 1458 return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len, 1459 ~csum_unfold(mpext->csum)); 1460 } 1461 1462 static void put_len_csum(u16 len, __sum16 csum, void *data) 1463 { 1464 __sum16 *sumptr = data + 2; 1465 __be16 *ptr = data; 1466 1467 put_unaligned_be16(len, ptr); 1468 1469 put_unaligned(csum, sumptr); 1470 } 1471 1472 void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp, 1473 struct mptcp_out_options *opts) 1474 { 1475 const struct sock *ssk = (const struct sock *)tp; 1476 struct mptcp_subflow_context *subflow; 1477 1478 /* Which options can be used together? 1479 * 1480 * X: mutually exclusive 1481 * O: often used together 1482 * C: can be used together in some cases 1483 * P: could be used together but we prefer not to (optimisations) 1484 * 1485 * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | 1486 * ------|------|------|------|------|------|------|------|------| 1487 * MPC |------|------|------|------|------|------|------|------| 1488 * MPJ | X |------|------|------|------|------|------|------| 1489 * DSS | X | X |------|------|------|------|------|------| 1490 * ADD | X | X | P |------|------|------|------|------| 1491 * RM | C | C | C | P |------|------|------|------| 1492 * PRIO | X | C | C | C | C |------|------|------| 1493 * FAIL | X | X | C | X | X | X |------|------| 1494 * FC | X | X | P | X | X | X | X |------| 1495 * RST | X | X | X | X | X | X | O | O | 1496 * ------|------|------|------|------|------|------|------|------| 1497 * 1498 * The same applies in mptcp_established_options() function. 1499 */ 1500 if (likely(OPTION_MPTCP_DSS & opts->suboptions)) { 1501 struct mptcp_ext *mpext = &opts->ext_copy; 1502 u8 len = TCPOLEN_MPTCP_DSS_BASE; 1503 u8 flags = 0; 1504 1505 if (mpext->use_ack) { 1506 flags = MPTCP_DSS_HAS_ACK; 1507 if (mpext->ack64) { 1508 len += TCPOLEN_MPTCP_DSS_ACK64; 1509 flags |= MPTCP_DSS_ACK64; 1510 } else { 1511 len += TCPOLEN_MPTCP_DSS_ACK32; 1512 } 1513 } 1514 1515 if (mpext->use_map) { 1516 len += TCPOLEN_MPTCP_DSS_MAP64; 1517 1518 /* Use only 64-bit mapping flags for now, add 1519 * support for optional 32-bit mappings later. 1520 */ 1521 flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64; 1522 if (mpext->data_fin) 1523 flags |= MPTCP_DSS_DATA_FIN; 1524 1525 if (opts->csum_reqd) 1526 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1527 } 1528 1529 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags); 1530 1531 if (mpext->use_ack) { 1532 struct mptcp_sock *msk; 1533 u64 ack_seq; 1534 1535 /* DSS option is set only by mptcp_established_options, 1536 * the caller is __tcp_transmit_skb() and ssk is always 1537 * not NULL. 1538 */ 1539 subflow = mptcp_subflow_ctx(ssk); 1540 msk = mptcp_sk(subflow->conn); 1541 ack_seq = READ_ONCE(msk->ack_seq); 1542 if (mpext->ack64) { 1543 put_unaligned_be64(ack_seq, ptr); 1544 ptr += 2; 1545 } else { 1546 put_unaligned_be32(ack_seq, ptr); 1547 ptr += 1; 1548 } 1549 subflow->rcv_wnd_sent = mptcp_set_rwin(msk, tp, th, 1550 ack_seq); 1551 } 1552 1553 if (mpext->use_map) { 1554 put_unaligned_be64(mpext->data_seq, ptr); 1555 ptr += 2; 1556 put_unaligned_be32(mpext->subflow_seq, ptr); 1557 ptr += 1; 1558 if (opts->csum_reqd) { 1559 /* data_len == 0 is reserved for the infinite mapping, 1560 * the checksum will also be set to 0. 1561 */ 1562 put_len_csum(mpext->data_len, 1563 (mpext->data_len ? mptcp_make_csum(mpext) : 0), 1564 ptr); 1565 } else { 1566 put_unaligned_be32(mpext->data_len << 16 | 1567 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1568 } 1569 ptr += 1; 1570 } 1571 1572 /* We might need to add MP_FAIL options in rare cases */ 1573 if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) 1574 goto mp_fail; 1575 } else if (OPTIONS_MPTCP_MPC & opts->suboptions) { 1576 u8 len, flag = MPTCP_CAP_HMAC_SHA256; 1577 1578 if (OPTION_MPTCP_MPC_SYN & opts->suboptions) { 1579 len = TCPOLEN_MPTCP_MPC_SYN; 1580 } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) { 1581 len = TCPOLEN_MPTCP_MPC_SYNACK; 1582 } else if (opts->data_len) { 1583 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 1584 if (opts->csum_reqd) 1585 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1586 } else { 1587 len = TCPOLEN_MPTCP_MPC_ACK; 1588 } 1589 1590 if (opts->csum_reqd) 1591 flag |= MPTCP_CAP_CHECKSUM_REQD; 1592 1593 if (!opts->allow_join_id0) 1594 flag |= MPTCP_CAP_DENY_JOIN_ID0; 1595 1596 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len, 1597 MPTCP_SUPPORTED_VERSION, 1598 flag); 1599 1600 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) & 1601 opts->suboptions)) 1602 goto mp_capable_done; 1603 1604 put_unaligned_be64(opts->sndr_key, ptr); 1605 ptr += 2; 1606 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions)) 1607 goto mp_capable_done; 1608 1609 put_unaligned_be64(opts->rcvr_key, ptr); 1610 ptr += 2; 1611 if (!opts->data_len) 1612 goto mp_capable_done; 1613 1614 if (opts->csum_reqd) { 1615 put_len_csum(opts->data_len, 1616 __mptcp_make_csum(opts->data_seq, 1617 opts->subflow_seq, 1618 opts->data_len, 1619 ~csum_unfold(opts->csum)), 1620 ptr); 1621 } else { 1622 put_unaligned_be32(opts->data_len << 16 | 1623 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1624 } 1625 ptr += 1; 1626 1627 /* MPC is additionally mutually exclusive with MP_PRIO */ 1628 goto mp_capable_done; 1629 } else if (OPTIONS_MPTCP_MPJ & opts->suboptions) { 1630 if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) { 1631 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1632 TCPOLEN_MPTCP_MPJ_SYN, 1633 opts->backup, opts->join_id); 1634 put_unaligned_be32(opts->token, ptr); 1635 ptr += 1; 1636 put_unaligned_be32(opts->nonce, ptr); 1637 ptr += 1; 1638 } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) { 1639 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1640 TCPOLEN_MPTCP_MPJ_SYNACK, 1641 opts->backup, opts->join_id); 1642 put_unaligned_be64(opts->thmac, ptr); 1643 ptr += 2; 1644 put_unaligned_be32(opts->nonce, ptr); 1645 ptr += 1; 1646 } else { 1647 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1648 TCPOLEN_MPTCP_MPJ_ACK, 0, 0); 1649 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN); 1650 ptr += 5; 1651 } 1652 } else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) { 1653 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE; 1654 u8 echo = MPTCP_ADDR_ECHO; 1655 1656 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1657 if (opts->addr.family == AF_INET6) 1658 len = TCPOLEN_MPTCP_ADD_ADDR6_BASE; 1659 #endif 1660 1661 if (opts->addr.port) 1662 len += TCPOLEN_MPTCP_PORT_LEN; 1663 1664 if (opts->ahmac) { 1665 len += sizeof(opts->ahmac); 1666 echo = 0; 1667 } 1668 1669 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR, 1670 len, echo, opts->addr.id); 1671 if (opts->addr.family == AF_INET) { 1672 memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4); 1673 ptr += 1; 1674 } 1675 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 1676 else if (opts->addr.family == AF_INET6) { 1677 memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16); 1678 ptr += 4; 1679 } 1680 #endif 1681 1682 if (!opts->addr.port) { 1683 if (opts->ahmac) { 1684 put_unaligned_be64(opts->ahmac, ptr); 1685 ptr += 2; 1686 } 1687 } else { 1688 u16 port = ntohs(opts->addr.port); 1689 1690 if (opts->ahmac) { 1691 u8 *bptr = (u8 *)ptr; 1692 1693 put_unaligned_be16(port, bptr); 1694 bptr += 2; 1695 put_unaligned_be64(opts->ahmac, bptr); 1696 bptr += 8; 1697 put_unaligned_be16(TCPOPT_NOP << 8 | 1698 TCPOPT_NOP, bptr); 1699 1700 ptr += 3; 1701 } else { 1702 put_unaligned_be32(port << 16 | 1703 TCPOPT_NOP << 8 | 1704 TCPOPT_NOP, ptr); 1705 ptr += 1; 1706 } 1707 } 1708 } else if (unlikely(OPTION_MPTCP_FASTCLOSE & opts->suboptions)) { 1709 /* FASTCLOSE is mutually exclusive with others except RST */ 1710 *ptr++ = mptcp_option(MPTCPOPT_MP_FASTCLOSE, 1711 TCPOLEN_MPTCP_FASTCLOSE, 1712 0, 0); 1713 put_unaligned_be64(opts->rcvr_key, ptr); 1714 ptr += 2; 1715 1716 if (OPTION_MPTCP_RST & opts->suboptions) 1717 goto mp_rst; 1718 return; 1719 } else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) { 1720 mp_fail: 1721 /* MP_FAIL is mutually exclusive with others except RST */ 1722 subflow = mptcp_subflow_ctx(ssk); 1723 subflow->send_mp_fail = 0; 1724 1725 *ptr++ = mptcp_option(MPTCPOPT_MP_FAIL, 1726 TCPOLEN_MPTCP_FAIL, 1727 0, 0); 1728 put_unaligned_be64(opts->fail_seq, ptr); 1729 ptr += 2; 1730 1731 if (OPTION_MPTCP_RST & opts->suboptions) 1732 goto mp_rst; 1733 return; 1734 } else if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) { 1735 mp_rst: 1736 *ptr++ = mptcp_option(MPTCPOPT_RST, 1737 TCPOLEN_MPTCP_RST, 1738 opts->reset_transient, 1739 opts->reset_reason); 1740 return; 1741 } else if (unlikely(!opts->suboptions)) { 1742 /* Fallback to TCP */ 1743 mptcp_track_rwin(tp); 1744 return; 1745 } 1746 1747 if (OPTION_MPTCP_PRIO & opts->suboptions) { 1748 subflow = mptcp_subflow_ctx(ssk); 1749 subflow->send_mp_prio = 0; 1750 1751 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO, 1752 TCPOLEN_MPTCP_PRIO, 1753 opts->backup, TCPOPT_NOP); 1754 1755 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPPRIOTX); 1756 } 1757 1758 mp_capable_done: 1759 if (OPTION_MPTCP_RM_ADDR & opts->suboptions) { 1760 u8 i = 1; 1761 1762 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR, 1763 TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr, 1764 0, opts->rm_list.ids[0]); 1765 1766 while (i < opts->rm_list.nr) { 1767 u8 id1, id2, id3, id4; 1768 1769 id1 = opts->rm_list.ids[i]; 1770 id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP; 1771 id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP; 1772 id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP; 1773 put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr); 1774 ptr += 1; 1775 i += 4; 1776 } 1777 } 1778 } 1779 1780 __be32 mptcp_get_reset_option(const struct sk_buff *skb) 1781 { 1782 const struct mptcp_ext *ext = mptcp_get_ext(skb); 1783 u8 flags, reason; 1784 1785 if (ext) { 1786 flags = ext->reset_transient; 1787 reason = ext->reset_reason; 1788 1789 return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST, 1790 flags, reason); 1791 } 1792 1793 return htonl(0u); 1794 } 1795 EXPORT_SYMBOL_GPL(mptcp_get_reset_option); 1796