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 18static bool mptcp_cap_flag_sha256(u8 flags) 19{ 20 return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256; 21} 22 23static 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 /* Cfr RFC 8684 Section 3.3.0: 54 * If a checksum is present but its use had 55 * not been negotiated in the MP_CAPABLE handshake, the receiver MUST 56 * close the subflow with a RST, as it is not behaving as negotiated. 57 * If a checksum is not present when its use has been negotiated, the 58 * receiver MUST close the subflow with a RST, as it is considered 59 * broken 60 * We parse even option with mismatching csum presence, so that 61 * later in subflow_data_ready we can trigger the reset. 62 */ 63 if (opsize != expected_opsize && 64 (expected_opsize != TCPOLEN_MPTCP_MPC_ACK_DATA || 65 opsize != TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM)) 66 break; 67 68 /* try to be gentle vs future versions on the initial syn */ 69 version = *ptr++ & MPTCP_VERSION_MASK; 70 if (opsize != TCPOLEN_MPTCP_MPC_SYN) { 71 if (version != MPTCP_SUPPORTED_VERSION) 72 break; 73 } else if (version < MPTCP_SUPPORTED_VERSION) { 74 break; 75 } 76 77 flags = *ptr++; 78 if (!mptcp_cap_flag_sha256(flags) || 79 (flags & MPTCP_CAP_EXTENSIBILITY)) 80 break; 81 82 /* RFC 6824, Section 3.1: 83 * "For the Checksum Required bit (labeled "A"), if either 84 * host requires the use of checksums, checksums MUST be used. 85 * In other words, the only way for checksums not to be used 86 * is if both hosts in their SYNs set A=0." 87 */ 88 if (flags & MPTCP_CAP_CHECKSUM_REQD) 89 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 90 91 mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0); 92 93 mp_opt->suboptions |= subopt; 94 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) { 95 mp_opt->sndr_key = get_unaligned_be64(ptr); 96 ptr += 8; 97 } 98 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) { 99 mp_opt->rcvr_key = get_unaligned_be64(ptr); 100 ptr += 8; 101 } 102 if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) { 103 /* Section 3.1.: 104 * "the data parameters in a MP_CAPABLE are semantically 105 * equivalent to those in a DSS option and can be used 106 * interchangeably." 107 */ 108 mp_opt->suboptions |= OPTION_MPTCP_DSS; 109 mp_opt->use_map = 1; 110 mp_opt->mpc_map = 1; 111 mp_opt->use_ack = 0; 112 mp_opt->data_len = get_unaligned_be16(ptr); 113 ptr += 2; 114 } 115 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) { 116 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 117 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 118 ptr += 2; 119 } 120 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u", 121 version, flags, opsize, mp_opt->sndr_key, 122 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum); 123 break; 124 125 case MPTCPOPT_MP_JOIN: 126 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) { 127 mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYN; 128 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 129 mp_opt->join_id = *ptr++; 130 mp_opt->token = get_unaligned_be32(ptr); 131 ptr += 4; 132 mp_opt->nonce = get_unaligned_be32(ptr); 133 ptr += 4; 134 pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u", 135 mp_opt->backup, mp_opt->join_id, 136 mp_opt->token, mp_opt->nonce); 137 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) { 138 mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYNACK; 139 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; 140 mp_opt->join_id = *ptr++; 141 mp_opt->thmac = get_unaligned_be64(ptr); 142 ptr += 8; 143 mp_opt->nonce = get_unaligned_be32(ptr); 144 ptr += 4; 145 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u", 146 mp_opt->backup, mp_opt->join_id, 147 mp_opt->thmac, mp_opt->nonce); 148 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) { 149 mp_opt->suboptions |= OPTION_MPTCP_MPJ_ACK; 150 ptr += 2; 151 memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN); 152 pr_debug("MP_JOIN hmac"); 153 } 154 break; 155 156 case MPTCPOPT_DSS: 157 pr_debug("DSS"); 158 ptr++; 159 160 /* we must clear 'mpc_map' be able to detect MP_CAPABLE 161 * map vs DSS map in mptcp_incoming_options(), and reconstruct 162 * map info accordingly 163 */ 164 mp_opt->mpc_map = 0; 165 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK; 166 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0; 167 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0; 168 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0; 169 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0; 170 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK); 171 172 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d", 173 mp_opt->data_fin, mp_opt->dsn64, 174 mp_opt->use_map, mp_opt->ack64, 175 mp_opt->use_ack); 176 177 expected_opsize = TCPOLEN_MPTCP_DSS_BASE; 178 179 if (mp_opt->use_ack) { 180 if (mp_opt->ack64) 181 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64; 182 else 183 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32; 184 } 185 186 if (mp_opt->use_map) { 187 if (mp_opt->dsn64) 188 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64; 189 else 190 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32; 191 } 192 193 /* Always parse any csum presence combination, we will enforce 194 * RFC 8684 Section 3.3.0 checks later in subflow_data_ready 195 */ 196 if (opsize != expected_opsize && 197 opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) 198 break; 199 200 mp_opt->suboptions |= OPTION_MPTCP_DSS; 201 if (mp_opt->use_ack) { 202 if (mp_opt->ack64) { 203 mp_opt->data_ack = get_unaligned_be64(ptr); 204 ptr += 8; 205 } else { 206 mp_opt->data_ack = get_unaligned_be32(ptr); 207 ptr += 4; 208 } 209 210 pr_debug("data_ack=%llu", mp_opt->data_ack); 211 } 212 213 if (mp_opt->use_map) { 214 if (mp_opt->dsn64) { 215 mp_opt->data_seq = get_unaligned_be64(ptr); 216 ptr += 8; 217 } else { 218 mp_opt->data_seq = get_unaligned_be32(ptr); 219 ptr += 4; 220 } 221 222 mp_opt->subflow_seq = get_unaligned_be32(ptr); 223 ptr += 4; 224 225 mp_opt->data_len = get_unaligned_be16(ptr); 226 ptr += 2; 227 228 if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { 229 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; 230 mp_opt->csum = get_unaligned((__force __sum16 *)ptr); 231 ptr += 2; 232 } 233 234 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u", 235 mp_opt->data_seq, mp_opt->subflow_seq, 236 mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD), 237 mp_opt->csum); 238 } 239 240 break; 241 242 case MPTCPOPT_ADD_ADDR: 243 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO; 244 if (!mp_opt->echo) { 245 if (opsize == TCPOLEN_MPTCP_ADD_ADDR || 246 opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT) 247 mp_opt->addr.family = AF_INET; 248#if IS_ENABLED(CONFIG_MPTCP_IPV6) 249 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 || 250 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT) 251 mp_opt->addr.family = AF_INET6; 252#endif 253 else 254 break; 255 } else { 256 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE || 257 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) 258 mp_opt->addr.family = AF_INET; 259#if IS_ENABLED(CONFIG_MPTCP_IPV6) 260 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE || 261 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) 262 mp_opt->addr.family = AF_INET6; 263#endif 264 else 265 break; 266 } 267 268 mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR; 269 mp_opt->addr.id = *ptr++; 270 mp_opt->addr.port = 0; 271 mp_opt->ahmac = 0; 272 if (mp_opt->addr.family == AF_INET) { 273 memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4); 274 ptr += 4; 275 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT || 276 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) { 277 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 278 ptr += 2; 279 } 280 } 281#if IS_ENABLED(CONFIG_MPTCP_IPV6) 282 else { 283 memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16); 284 ptr += 16; 285 if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT || 286 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) { 287 mp_opt->addr.port = htons(get_unaligned_be16(ptr)); 288 ptr += 2; 289 } 290 } 291#endif 292 if (!mp_opt->echo) { 293 mp_opt->ahmac = get_unaligned_be64(ptr); 294 ptr += 8; 295 } 296 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d", 297 (mp_opt->addr.family == AF_INET6) ? "6" : "", 298 mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port)); 299 break; 300 301 case MPTCPOPT_RM_ADDR: 302 if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 || 303 opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX) 304 break; 305 306 ptr++; 307 308 mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR; 309 mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE; 310 for (i = 0; i < mp_opt->rm_list.nr; i++) 311 mp_opt->rm_list.ids[i] = *ptr++; 312 pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr); 313 break; 314 315 case MPTCPOPT_MP_PRIO: 316 if (opsize != TCPOLEN_MPTCP_PRIO) 317 break; 318 319 mp_opt->suboptions |= OPTION_MPTCP_PRIO; 320 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP; 321 pr_debug("MP_PRIO: prio=%d", mp_opt->backup); 322 break; 323 324 case MPTCPOPT_MP_FASTCLOSE: 325 if (opsize != TCPOLEN_MPTCP_FASTCLOSE) 326 break; 327 328 ptr += 2; 329 mp_opt->rcvr_key = get_unaligned_be64(ptr); 330 ptr += 8; 331 mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE; 332 pr_debug("MP_FASTCLOSE: recv_key=%llu", mp_opt->rcvr_key); 333 break; 334 335 case MPTCPOPT_RST: 336 if (opsize != TCPOLEN_MPTCP_RST) 337 break; 338 339 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) 340 break; 341 342 mp_opt->suboptions |= OPTION_MPTCP_RST; 343 flags = *ptr++; 344 mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT; 345 mp_opt->reset_reason = *ptr; 346 pr_debug("MP_RST: transient=%u reason=%u", 347 mp_opt->reset_transient, mp_opt->reset_reason); 348 break; 349 350 case MPTCPOPT_MP_FAIL: 351 if (opsize != TCPOLEN_MPTCP_FAIL) 352 break; 353 354 ptr += 2; 355 mp_opt->suboptions |= OPTION_MPTCP_FAIL; 356 mp_opt->fail_seq = get_unaligned_be64(ptr); 357 pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq); 358 break; 359 360 default: 361 break; 362 } 363} 364 365void mptcp_get_options(const struct sk_buff *skb, 366 struct mptcp_options_received *mp_opt) 367{ 368 const struct tcphdr *th = tcp_hdr(skb); 369 const unsigned char *ptr; 370 int length; 371 372 /* initialize option status */ 373 mp_opt->suboptions = 0; 374 375 length = (th->doff * 4) - sizeof(struct tcphdr); 376 ptr = (const unsigned char *)(th + 1); 377 378 while (length > 0) { 379 int opcode = *ptr++; 380 int opsize; 381 382 switch (opcode) { 383 case TCPOPT_EOL: 384 return; 385 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ 386 length--; 387 continue; 388 default: 389 if (length < 2) 390 return; 391 opsize = *ptr++; 392 if (opsize < 2) /* "silly options" */ 393 return; 394 if (opsize > length) 395 return; /* don't parse partial options */ 396 if (opcode == TCPOPT_MPTCP) 397 mptcp_parse_option(skb, ptr, opsize, mp_opt); 398 ptr += opsize - 2; 399 length -= opsize; 400 } 401 } 402} 403 404bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb, 405 unsigned int *size, struct mptcp_out_options *opts) 406{ 407 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 408 409 /* we will use snd_isn to detect first pkt [re]transmission 410 * in mptcp_established_options_mp() 411 */ 412 subflow->snd_isn = TCP_SKB_CB(skb)->end_seq; 413 if (subflow->request_mptcp) { 414 opts->suboptions = OPTION_MPTCP_MPC_SYN; 415 opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk)); 416 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 417 *size = TCPOLEN_MPTCP_MPC_SYN; 418 return true; 419 } else if (subflow->request_join) { 420 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token, 421 subflow->local_nonce); 422 opts->suboptions = OPTION_MPTCP_MPJ_SYN; 423 opts->join_id = subflow->local_id; 424 opts->token = subflow->remote_token; 425 opts->nonce = subflow->local_nonce; 426 opts->backup = subflow->request_bkup; 427 *size = TCPOLEN_MPTCP_MPJ_SYN; 428 return true; 429 } 430 return false; 431} 432 433static void clear_3rdack_retransmission(struct sock *sk) 434{ 435 struct inet_connection_sock *icsk = inet_csk(sk); 436 437 sk_stop_timer(sk, &icsk->icsk_delack_timer); 438 icsk->icsk_ack.timeout = 0; 439 icsk->icsk_ack.ato = 0; 440 icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER); 441} 442 443static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, 444 bool snd_data_fin_enable, 445 unsigned int *size, 446 struct mptcp_out_options *opts) 447{ 448 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 449 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 450 struct mptcp_ext *mpext; 451 unsigned int data_len; 452 u8 len; 453 454 /* When skb is not available, we better over-estimate the emitted 455 * options len. A full DSS option (28 bytes) is longer than 456 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so 457 * tell the caller to defer the estimate to 458 * mptcp_established_options_dss(), which will reserve enough space. 459 */ 460 if (!skb) 461 return false; 462 463 /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */ 464 if (subflow->fully_established || snd_data_fin_enable || 465 subflow->snd_isn != TCP_SKB_CB(skb)->seq || 466 sk->sk_state != TCP_ESTABLISHED) 467 return false; 468 469 if (subflow->mp_capable) { 470 mpext = mptcp_get_ext(skb); 471 data_len = mpext ? mpext->data_len : 0; 472 473 /* we will check ops->data_len in mptcp_write_options() to 474 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and 475 * TCPOLEN_MPTCP_MPC_ACK 476 */ 477 opts->data_len = data_len; 478 opts->suboptions = OPTION_MPTCP_MPC_ACK; 479 opts->sndr_key = subflow->local_key; 480 opts->rcvr_key = subflow->remote_key; 481 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 482 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); 483 484 /* Section 3.1. 485 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK 486 * packets that start the first subflow of an MPTCP connection, 487 * as well as the first packet that carries data 488 */ 489 if (data_len > 0) { 490 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 491 if (opts->csum_reqd) { 492 /* we need to propagate more info to csum the pseudo hdr */ 493 opts->data_seq = mpext->data_seq; 494 opts->subflow_seq = mpext->subflow_seq; 495 opts->csum = mpext->csum; 496 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 497 } 498 *size = ALIGN(len, 4); 499 } else { 500 *size = TCPOLEN_MPTCP_MPC_ACK; 501 } 502 503 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d", 504 subflow, subflow->local_key, subflow->remote_key, 505 data_len); 506 507 return true; 508 } else if (subflow->mp_join) { 509 opts->suboptions = OPTION_MPTCP_MPJ_ACK; 510 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN); 511 *size = TCPOLEN_MPTCP_MPJ_ACK; 512 pr_debug("subflow=%p", subflow); 513 514 /* we can use the full delegate action helper only from BH context 515 * If we are in process context - sk is flushing the backlog at 516 * socket lock release time - just set the appropriate flag, will 517 * be handled by the release callback 518 */ 519 if (sock_owned_by_user(sk)) 520 set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status); 521 else 522 mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK); 523 return true; 524 } 525 return false; 526} 527 528static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow, 529 struct sk_buff *skb, struct mptcp_ext *ext) 530{ 531 /* The write_seq value has already been incremented, so the actual 532 * sequence number for the DATA_FIN is one less. 533 */ 534 u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1; 535 536 if (!ext->use_map || !skb->len) { 537 /* RFC6824 requires a DSS mapping with specific values 538 * if DATA_FIN is set but no data payload is mapped 539 */ 540 ext->data_fin = 1; 541 ext->use_map = 1; 542 ext->dsn64 = 1; 543 ext->data_seq = data_fin_tx_seq; 544 ext->subflow_seq = 0; 545 ext->data_len = 1; 546 } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) { 547 /* If there's an existing DSS mapping and it is the 548 * final mapping, DATA_FIN consumes 1 additional byte of 549 * mapping space. 550 */ 551 ext->data_fin = 1; 552 ext->data_len++; 553 } 554} 555 556static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, 557 bool snd_data_fin_enable, 558 unsigned int *size, 559 struct mptcp_out_options *opts) 560{ 561 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 562 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 563 unsigned int dss_size = 0; 564 struct mptcp_ext *mpext; 565 unsigned int ack_size; 566 bool ret = false; 567 u64 ack_seq; 568 569 opts->csum_reqd = READ_ONCE(msk->csum_enabled); 570 mpext = skb ? mptcp_get_ext(skb) : NULL; 571 572 if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) { 573 unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64; 574 575 if (mpext) { 576 if (opts->csum_reqd) 577 map_size += TCPOLEN_MPTCP_DSS_CHECKSUM; 578 579 opts->ext_copy = *mpext; 580 } 581 582 dss_size = map_size; 583 if (skb && snd_data_fin_enable) 584 mptcp_write_data_fin(subflow, skb, &opts->ext_copy); 585 opts->suboptions = OPTION_MPTCP_DSS; 586 ret = true; 587 } 588 589 /* passive sockets msk will set the 'can_ack' after accept(), even 590 * if the first subflow may have the already the remote key handy 591 */ 592 opts->ext_copy.use_ack = 0; 593 if (!READ_ONCE(msk->can_ack)) { 594 *size = ALIGN(dss_size, 4); 595 return ret; 596 } 597 598 ack_seq = READ_ONCE(msk->ack_seq); 599 if (READ_ONCE(msk->use_64bit_ack)) { 600 ack_size = TCPOLEN_MPTCP_DSS_ACK64; 601 opts->ext_copy.data_ack = ack_seq; 602 opts->ext_copy.ack64 = 1; 603 } else { 604 ack_size = TCPOLEN_MPTCP_DSS_ACK32; 605 opts->ext_copy.data_ack32 = (uint32_t)ack_seq; 606 opts->ext_copy.ack64 = 0; 607 } 608 opts->ext_copy.use_ack = 1; 609 opts->suboptions = OPTION_MPTCP_DSS; 610 WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk)); 611 612 /* Add kind/length/subtype/flag overhead if mapping is not populated */ 613 if (dss_size == 0) 614 ack_size += TCPOLEN_MPTCP_DSS_BASE; 615 616 dss_size += ack_size; 617 618 *size = ALIGN(dss_size, 4); 619 return true; 620} 621 622static u64 add_addr_generate_hmac(u64 key1, u64 key2, 623 struct mptcp_addr_info *addr) 624{ 625 u16 port = ntohs(addr->port); 626 u8 hmac[SHA256_DIGEST_SIZE]; 627 u8 msg[19]; 628 int i = 0; 629 630 msg[i++] = addr->id; 631 if (addr->family == AF_INET) { 632 memcpy(&msg[i], &addr->addr.s_addr, 4); 633 i += 4; 634 } 635#if IS_ENABLED(CONFIG_MPTCP_IPV6) 636 else if (addr->family == AF_INET6) { 637 memcpy(&msg[i], &addr->addr6.s6_addr, 16); 638 i += 16; 639 } 640#endif 641 msg[i++] = port >> 8; 642 msg[i++] = port & 0xFF; 643 644 mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac); 645 646 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]); 647} 648 649static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb, 650 unsigned int *size, 651 unsigned int remaining, 652 struct mptcp_out_options *opts) 653{ 654 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 655 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 656 bool drop_other_suboptions = false; 657 unsigned int opt_size = *size; 658 bool echo; 659 int len; 660 661 /* add addr will strip the existing options, be sure to avoid breaking 662 * MPC/MPJ handshakes 663 */ 664 if (!mptcp_pm_should_add_signal(msk) || 665 (opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) || 666 !mptcp_pm_add_addr_signal(msk, skb, opt_size, remaining, &opts->addr, 667 &echo, &drop_other_suboptions)) 668 return false; 669 670 if (drop_other_suboptions) 671 remaining += opt_size; 672 len = mptcp_add_addr_len(opts->addr.family, echo, !!opts->addr.port); 673 if (remaining < len) 674 return false; 675 676 *size = len; 677 if (drop_other_suboptions) { 678 pr_debug("drop other suboptions"); 679 opts->suboptions = 0; 680 681 /* note that e.g. DSS could have written into the memory 682 * aliased by ahmac, we must reset the field here 683 * to avoid appending the hmac even for ADD_ADDR echo 684 * options 685 */ 686 opts->ahmac = 0; 687 *size -= opt_size; 688 } 689 opts->suboptions |= OPTION_MPTCP_ADD_ADDR; 690 if (!echo) { 691 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDRTX); 692 opts->ahmac = add_addr_generate_hmac(READ_ONCE(msk->local_key), 693 READ_ONCE(msk->remote_key), 694 &opts->addr); 695 } else { 696 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADDTX); 697 } 698 pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d", 699 opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port)); 700 701 return true; 702} 703 704static bool mptcp_established_options_rm_addr(struct sock *sk, 705 unsigned int *size, 706 unsigned int remaining, 707 struct mptcp_out_options *opts) 708{ 709 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 710 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 711 struct mptcp_rm_list rm_list; 712 int i, len; 713 714 if (!mptcp_pm_should_rm_signal(msk) || 715 !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list))) 716 return false; 717 718 len = mptcp_rm_addr_len(&rm_list); 719 if (len < 0) 720 return false; 721 if (remaining < len) 722 return false; 723 724 *size = len; 725 opts->suboptions |= OPTION_MPTCP_RM_ADDR; 726 opts->rm_list = rm_list; 727 728 for (i = 0; i < opts->rm_list.nr; i++) 729 pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]); 730 MPTCP_ADD_STATS(sock_net(sk), MPTCP_MIB_RMADDRTX, opts->rm_list.nr); 731 return true; 732} 733 734static bool mptcp_established_options_mp_prio(struct sock *sk, 735 unsigned int *size, 736 unsigned int remaining, 737 struct mptcp_out_options *opts) 738{ 739 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 740 741 /* can't send MP_PRIO with MPC, as they share the same option space: 742 * 'backup'. Also it makes no sense at all 743 */ 744 if (!subflow->send_mp_prio || (opts->suboptions & OPTIONS_MPTCP_MPC)) 745 return false; 746 747 /* account for the trailing 'nop' option */ 748 if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN) 749 return false; 750 751 *size = TCPOLEN_MPTCP_PRIO_ALIGN; 752 opts->suboptions |= OPTION_MPTCP_PRIO; 753 opts->backup = subflow->request_bkup; 754 755 pr_debug("prio=%d", opts->backup); 756 757 return true; 758} 759 760static noinline bool mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb, 761 unsigned int *size, 762 unsigned int remaining, 763 struct mptcp_out_options *opts) 764{ 765 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 766 767 if (remaining < TCPOLEN_MPTCP_RST) 768 return false; 769 770 *size = TCPOLEN_MPTCP_RST; 771 opts->suboptions |= OPTION_MPTCP_RST; 772 opts->reset_transient = subflow->reset_transient; 773 opts->reset_reason = subflow->reset_reason; 774 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTTX); 775 776 return true; 777} 778 779static bool mptcp_established_options_fastclose(struct sock *sk, 780 unsigned int *size, 781 unsigned int remaining, 782 struct mptcp_out_options *opts) 783{ 784 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 785 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 786 787 if (likely(!subflow->send_fastclose)) 788 return false; 789 790 if (remaining < TCPOLEN_MPTCP_FASTCLOSE) 791 return false; 792 793 *size = TCPOLEN_MPTCP_FASTCLOSE; 794 opts->suboptions |= OPTION_MPTCP_FASTCLOSE; 795 opts->rcvr_key = READ_ONCE(msk->remote_key); 796 797 pr_debug("FASTCLOSE key=%llu", opts->rcvr_key); 798 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSETX); 799 return true; 800} 801 802static bool mptcp_established_options_mp_fail(struct sock *sk, 803 unsigned int *size, 804 unsigned int remaining, 805 struct mptcp_out_options *opts) 806{ 807 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 808 809 if (likely(!subflow->send_mp_fail)) 810 return false; 811 812 if (remaining < TCPOLEN_MPTCP_FAIL) 813 return false; 814 815 *size = TCPOLEN_MPTCP_FAIL; 816 opts->suboptions |= OPTION_MPTCP_FAIL; 817 opts->fail_seq = subflow->map_seq; 818 819 pr_debug("MP_FAIL fail_seq=%llu", opts->fail_seq); 820 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX); 821 822 return true; 823} 824 825bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, 826 unsigned int *size, unsigned int remaining, 827 struct mptcp_out_options *opts) 828{ 829 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 830 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 831 unsigned int opt_size = 0; 832 bool snd_data_fin; 833 bool ret = false; 834 835 opts->suboptions = 0; 836 837 if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb))) 838 return false; 839 840 if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) { 841 if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) || 842 mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) { 843 *size += opt_size; 844 remaining -= opt_size; 845 } 846 /* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */ 847 if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) { 848 *size += opt_size; 849 remaining -= opt_size; 850 } 851 return true; 852 } 853 854 snd_data_fin = mptcp_data_fin_enabled(msk); 855 if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, opts)) 856 ret = true; 857 else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, opts)) { 858 unsigned int mp_fail_size; 859 860 ret = true; 861 if (mptcp_established_options_mp_fail(sk, &mp_fail_size, 862 remaining - opt_size, opts)) { 863 *size += opt_size + mp_fail_size; 864 remaining -= opt_size - mp_fail_size; 865 return true; 866 } 867 } 868 869 /* we reserved enough space for the above options, and exceeding the 870 * TCP option space would be fatal 871 */ 872 if (WARN_ON_ONCE(opt_size > remaining)) 873 return false; 874 875 *size += opt_size; 876 remaining -= opt_size; 877 if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) { 878 *size += opt_size; 879 remaining -= opt_size; 880 ret = true; 881 } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) { 882 *size += opt_size; 883 remaining -= opt_size; 884 ret = true; 885 } 886 887 if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) { 888 *size += opt_size; 889 remaining -= opt_size; 890 ret = true; 891 } 892 893 return ret; 894} 895 896bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, 897 struct mptcp_out_options *opts) 898{ 899 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); 900 901 if (subflow_req->mp_capable) { 902 opts->suboptions = OPTION_MPTCP_MPC_SYNACK; 903 opts->sndr_key = subflow_req->local_key; 904 opts->csum_reqd = subflow_req->csum_reqd; 905 opts->allow_join_id0 = subflow_req->allow_join_id0; 906 *size = TCPOLEN_MPTCP_MPC_SYNACK; 907 pr_debug("subflow_req=%p, local_key=%llu", 908 subflow_req, subflow_req->local_key); 909 return true; 910 } else if (subflow_req->mp_join) { 911 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK; 912 opts->backup = subflow_req->backup; 913 opts->join_id = subflow_req->local_id; 914 opts->thmac = subflow_req->thmac; 915 opts->nonce = subflow_req->local_nonce; 916 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u", 917 subflow_req, opts->backup, opts->join_id, 918 opts->thmac, opts->nonce); 919 *size = TCPOLEN_MPTCP_MPJ_SYNACK; 920 return true; 921 } 922 return false; 923} 924 925static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 926 struct mptcp_subflow_context *subflow, 927 struct sk_buff *skb, 928 struct mptcp_options_received *mp_opt) 929{ 930 /* here we can process OoO, in-window pkts, only in-sequence 4th ack 931 * will make the subflow fully established 932 */ 933 if (likely(subflow->fully_established)) { 934 /* on passive sockets, check for 3rd ack retransmission 935 * note that msk is always set by subflow_syn_recv_sock() 936 * for mp_join subflows 937 */ 938 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 && 939 TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq && 940 subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) && 941 !subflow->request_join) 942 tcp_send_ack(ssk); 943 goto check_notify; 944 } 945 946 /* we must process OoO packets before the first subflow is fully 947 * established. OoO packets are instead a protocol violation 948 * for MP_JOIN subflows as the peer must not send any data 949 * before receiving the forth ack - cfr. RFC 8684 section 3.2. 950 */ 951 if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) { 952 if (subflow->mp_join) 953 goto reset; 954 if (subflow->is_mptfo && mp_opt->suboptions & OPTION_MPTCP_MPC_ACK) 955 goto set_fully_established; 956 return subflow->mp_capable; 957 } 958 959 if (subflow->remote_key_valid && 960 (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) || 961 ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo))) { 962 /* subflows are fully established as soon as we get any 963 * additional ack, including ADD_ADDR. 964 */ 965 goto set_fully_established; 966 } 967 968 /* If the first established packet does not contain MP_CAPABLE + data 969 * then fallback to TCP. Fallback scenarios requires a reset for 970 * MP_JOIN subflows. 971 */ 972 if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) { 973 if (subflow->mp_join) 974 goto reset; 975 subflow->mp_capable = 0; 976 pr_fallback(msk); 977 mptcp_do_fallback(ssk); 978 return false; 979 } 980 981 if (mp_opt->deny_join_id0) 982 WRITE_ONCE(msk->pm.remote_deny_join_id0, true); 983 984 if (unlikely(!READ_ONCE(msk->pm.server_side))) 985 pr_warn_once("bogus mpc option on established client sk"); 986 987set_fully_established: 988 mptcp_data_lock((struct sock *)msk); 989 __mptcp_subflow_fully_established(msk, subflow, mp_opt); 990 mptcp_data_unlock((struct sock *)msk); 991 992check_notify: 993 /* if the subflow is not already linked into the conn_list, we can't 994 * notify the PM: this subflow is still on the listener queue 995 * and the PM possibly acquiring the subflow lock could race with 996 * the listener close 997 */ 998 if (likely(subflow->pm_notified) || list_empty(&subflow->node)) 999 return true; 1000 1001 subflow->pm_notified = 1; 1002 if (subflow->mp_join) { 1003 clear_3rdack_retransmission(ssk); 1004 mptcp_pm_subflow_established(msk); 1005 } else { 1006 mptcp_pm_fully_established(msk, ssk); 1007 } 1008 return true; 1009 1010reset: 1011 mptcp_subflow_reset(ssk); 1012 return false; 1013} 1014 1015u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq) 1016{ 1017 u32 old_seq32, cur_seq32; 1018 1019 old_seq32 = (u32)old_seq; 1020 cur_seq32 = (u32)cur_seq; 1021 cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32; 1022 if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32))) 1023 return cur_seq + (1LL << 32); 1024 1025 /* reverse wrap could happen, too */ 1026 if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32))) 1027 return cur_seq - (1LL << 32); 1028 return cur_seq; 1029} 1030 1031static void __mptcp_snd_una_update(struct mptcp_sock *msk, u64 new_snd_una) 1032{ 1033 msk->bytes_acked += new_snd_una - msk->snd_una; 1034 WRITE_ONCE(msk->snd_una, new_snd_una); 1035} 1036 1037static void ack_update_msk(struct mptcp_sock *msk, 1038 struct sock *ssk, 1039 struct mptcp_options_received *mp_opt) 1040{ 1041 u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt); 1042 struct sock *sk = (struct sock *)msk; 1043 u64 old_snd_una; 1044 1045 mptcp_data_lock(sk); 1046 1047 /* avoid ack expansion on update conflict, to reduce the risk of 1048 * wrongly expanding to a future ack sequence number, which is way 1049 * more dangerous than missing an ack 1050 */ 1051 old_snd_una = msk->snd_una; 1052 new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64); 1053 1054 /* ACK for data not even sent yet? Ignore.*/ 1055 if (unlikely(after64(new_snd_una, snd_nxt))) 1056 new_snd_una = old_snd_una; 1057 1058 new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd; 1059 1060 if (after64(new_wnd_end, msk->wnd_end)) 1061 WRITE_ONCE(msk->wnd_end, new_wnd_end); 1062 1063 /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */ 1064 if (after64(msk->wnd_end, snd_nxt)) 1065 __mptcp_check_push(sk, ssk); 1066 1067 if (after64(new_snd_una, old_snd_una)) { 1068 __mptcp_snd_una_update(msk, new_snd_una); 1069 __mptcp_data_acked(sk); 1070 } 1071 mptcp_data_unlock(sk); 1072 1073 trace_ack_update_msk(mp_opt->data_ack, 1074 old_snd_una, new_snd_una, 1075 new_wnd_end, READ_ONCE(msk->wnd_end)); 1076} 1077 1078bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit) 1079{ 1080 /* Skip if DATA_FIN was already received. 1081 * If updating simultaneously with the recvmsg loop, values 1082 * should match. If they mismatch, the peer is misbehaving and 1083 * we will prefer the most recent information. 1084 */ 1085 if (READ_ONCE(msk->rcv_data_fin)) 1086 return false; 1087 1088 WRITE_ONCE(msk->rcv_data_fin_seq, 1089 mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit)); 1090 WRITE_ONCE(msk->rcv_data_fin, 1); 1091 1092 return true; 1093} 1094 1095static bool add_addr_hmac_valid(struct mptcp_sock *msk, 1096 struct mptcp_options_received *mp_opt) 1097{ 1098 u64 hmac = 0; 1099 1100 if (mp_opt->echo) 1101 return true; 1102 1103 hmac = add_addr_generate_hmac(READ_ONCE(msk->remote_key), 1104 READ_ONCE(msk->local_key), 1105 &mp_opt->addr); 1106 1107 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n", 1108 msk, hmac, mp_opt->ahmac); 1109 1110 return hmac == mp_opt->ahmac; 1111} 1112 1113/* Return false if a subflow has been reset, else return true */ 1114bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 1115{ 1116 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); 1117 struct mptcp_sock *msk = mptcp_sk(subflow->conn); 1118 struct mptcp_options_received mp_opt; 1119 struct mptcp_ext *mpext; 1120 1121 if (__mptcp_check_fallback(msk)) { 1122 /* Keep it simple and unconditionally trigger send data cleanup and 1123 * pending queue spooling. We will need to acquire the data lock 1124 * for more accurate checks, and once the lock is acquired, such 1125 * helpers are cheap. 1126 */ 1127 mptcp_data_lock(subflow->conn); 1128 if (sk_stream_memory_free(sk)) 1129 __mptcp_check_push(subflow->conn, sk); 1130 1131 /* on fallback we just need to ignore the msk-level snd_una, as 1132 * this is really plain TCP 1133 */ 1134 __mptcp_snd_una_update(msk, READ_ONCE(msk->snd_nxt)); 1135 1136 __mptcp_data_acked(subflow->conn); 1137 mptcp_data_unlock(subflow->conn); 1138 return true; 1139 } 1140 1141 mptcp_get_options(skb, &mp_opt); 1142 1143 /* The subflow can be in close state only if check_fully_established() 1144 * just sent a reset. If so, tell the caller to ignore the current packet. 1145 */ 1146 if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) 1147 return sk->sk_state != TCP_CLOSE; 1148 1149 if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) { 1150 if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) && 1151 READ_ONCE(msk->local_key) == mp_opt.rcvr_key) { 1152 WRITE_ONCE(msk->rcv_fastclose, true); 1153 mptcp_schedule_work((struct sock *)msk); 1154 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX); 1155 } 1156 1157 if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) && 1158 add_addr_hmac_valid(msk, &mp_opt)) { 1159 if (!mp_opt.echo) { 1160 mptcp_pm_add_addr_received(sk, &mp_opt.addr); 1161 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR); 1162 } else { 1163 mptcp_pm_add_addr_echoed(msk, &mp_opt.addr); 1164 mptcp_pm_del_add_timer(msk, &mp_opt.addr, true); 1165 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD); 1166 } 1167 1168 if (mp_opt.addr.port) 1169 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD); 1170 } 1171 1172 if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR) 1173 mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list); 1174 1175 if (mp_opt.suboptions & OPTION_MPTCP_PRIO) { 1176 mptcp_pm_mp_prio_received(sk, mp_opt.backup); 1177 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX); 1178 } 1179 1180 if (mp_opt.suboptions & OPTION_MPTCP_FAIL) { 1181 mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq); 1182 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX); 1183 } 1184 1185 if (mp_opt.suboptions & OPTION_MPTCP_RST) { 1186 subflow->reset_seen = 1; 1187 subflow->reset_reason = mp_opt.reset_reason; 1188 subflow->reset_transient = mp_opt.reset_transient; 1189 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTRX); 1190 } 1191 1192 if (!(mp_opt.suboptions & OPTION_MPTCP_DSS)) 1193 return true; 1194 } 1195 1196 /* we can't wait for recvmsg() to update the ack_seq, otherwise 1197 * monodirectional flows will stuck 1198 */ 1199 if (mp_opt.use_ack) 1200 ack_update_msk(msk, sk, &mp_opt); 1201 1202 /* Zero-data-length packets are dropped by the caller and not 1203 * propagated to the MPTCP layer, so the skb extension does not 1204 * need to be allocated or populated. DATA_FIN information, if 1205 * present, needs to be updated here before the skb is freed. 1206 */ 1207 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) { 1208 if (mp_opt.data_fin && mp_opt.data_len == 1 && 1209 mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64)) 1210 mptcp_schedule_work((struct sock *)msk); 1211 1212 return true; 1213 } 1214 1215 mpext = skb_ext_add(skb, SKB_EXT_MPTCP); 1216 if (!mpext) 1217 return true; 1218 1219 memset(mpext, 0, sizeof(*mpext)); 1220 1221 if (likely(mp_opt.use_map)) { 1222 if (mp_opt.mpc_map) { 1223 /* this is an MP_CAPABLE carrying MPTCP data 1224 * we know this map the first chunk of data 1225 */ 1226 mptcp_crypto_key_sha(subflow->remote_key, NULL, 1227 &mpext->data_seq); 1228 mpext->data_seq++; 1229 mpext->subflow_seq = 1; 1230 mpext->dsn64 = 1; 1231 mpext->mpc_map = 1; 1232 mpext->data_fin = 0; 1233 } else { 1234 mpext->data_seq = mp_opt.data_seq; 1235 mpext->subflow_seq = mp_opt.subflow_seq; 1236 mpext->dsn64 = mp_opt.dsn64; 1237 mpext->data_fin = mp_opt.data_fin; 1238 } 1239 mpext->data_len = mp_opt.data_len; 1240 mpext->use_map = 1; 1241 mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD); 1242 1243 if (mpext->csum_reqd) 1244 mpext->csum = mp_opt.csum; 1245 } 1246 1247 return true; 1248} 1249 1250static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th) 1251{ 1252 const struct sock *ssk = (const struct sock *)tp; 1253 struct mptcp_subflow_context *subflow; 1254 u64 ack_seq, rcv_wnd_old, rcv_wnd_new; 1255 struct mptcp_sock *msk; 1256 u32 new_win; 1257 u64 win; 1258 1259 subflow = mptcp_subflow_ctx(ssk); 1260 msk = mptcp_sk(subflow->conn); 1261 1262 ack_seq = READ_ONCE(msk->ack_seq); 1263 rcv_wnd_new = ack_seq + tp->rcv_wnd; 1264 1265 rcv_wnd_old = atomic64_read(&msk->rcv_wnd_sent); 1266 if (after64(rcv_wnd_new, rcv_wnd_old)) { 1267 u64 rcv_wnd; 1268 1269 for (;;) { 1270 rcv_wnd = atomic64_cmpxchg(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new); 1271 1272 if (rcv_wnd == rcv_wnd_old) 1273 break; 1274 1275 rcv_wnd_old = rcv_wnd; 1276 if (before64(rcv_wnd_new, rcv_wnd_old)) { 1277 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE); 1278 goto raise_win; 1279 } 1280 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT); 1281 } 1282 return; 1283 } 1284 1285 if (rcv_wnd_new != rcv_wnd_old) { 1286raise_win: 1287 win = rcv_wnd_old - ack_seq; 1288 tp->rcv_wnd = min_t(u64, win, U32_MAX); 1289 new_win = tp->rcv_wnd; 1290 1291 /* Make sure we do not exceed the maximum possible 1292 * scaled window. 1293 */ 1294 if (unlikely(th->syn)) 1295 new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale; 1296 if (!tp->rx_opt.rcv_wscale && 1297 READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows)) 1298 new_win = min(new_win, MAX_TCP_WINDOW); 1299 else 1300 new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 1301 1302 /* RFC1323 scaling applied */ 1303 new_win >>= tp->rx_opt.rcv_wscale; 1304 th->window = htons(new_win); 1305 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED); 1306 } 1307} 1308 1309__sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum) 1310{ 1311 struct csum_pseudo_header header; 1312 __wsum csum; 1313 1314 /* cfr RFC 8684 3.3.1.: 1315 * the data sequence number used in the pseudo-header is 1316 * always the 64-bit value, irrespective of what length is used in the 1317 * DSS option itself. 1318 */ 1319 header.data_seq = cpu_to_be64(data_seq); 1320 header.subflow_seq = htonl(subflow_seq); 1321 header.data_len = htons(data_len); 1322 header.csum = 0; 1323 1324 csum = csum_partial(&header, sizeof(header), sum); 1325 return csum_fold(csum); 1326} 1327 1328static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext) 1329{ 1330 return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len, 1331 ~csum_unfold(mpext->csum)); 1332} 1333 1334static void put_len_csum(u16 len, __sum16 csum, void *data) 1335{ 1336 __sum16 *sumptr = data + 2; 1337 __be16 *ptr = data; 1338 1339 put_unaligned_be16(len, ptr); 1340 1341 put_unaligned(csum, sumptr); 1342} 1343 1344void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp, 1345 struct mptcp_out_options *opts) 1346{ 1347 const struct sock *ssk = (const struct sock *)tp; 1348 struct mptcp_subflow_context *subflow; 1349 1350 /* Which options can be used together? 1351 * 1352 * X: mutually exclusive 1353 * O: often used together 1354 * C: can be used together in some cases 1355 * P: could be used together but we prefer not to (optimisations) 1356 * 1357 * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | 1358 * ------|------|------|------|------|------|------|------|------| 1359 * MPC |------|------|------|------|------|------|------|------| 1360 * MPJ | X |------|------|------|------|------|------|------| 1361 * DSS | X | X |------|------|------|------|------|------| 1362 * ADD | X | X | P |------|------|------|------|------| 1363 * RM | C | C | C | P |------|------|------|------| 1364 * PRIO | X | C | C | C | C |------|------|------| 1365 * FAIL | X | X | C | X | X | X |------|------| 1366 * FC | X | X | X | X | X | X | X |------| 1367 * RST | X | X | X | X | X | X | O | O | 1368 * ------|------|------|------|------|------|------|------|------| 1369 * 1370 * The same applies in mptcp_established_options() function. 1371 */ 1372 if (likely(OPTION_MPTCP_DSS & opts->suboptions)) { 1373 struct mptcp_ext *mpext = &opts->ext_copy; 1374 u8 len = TCPOLEN_MPTCP_DSS_BASE; 1375 u8 flags = 0; 1376 1377 if (mpext->use_ack) { 1378 flags = MPTCP_DSS_HAS_ACK; 1379 if (mpext->ack64) { 1380 len += TCPOLEN_MPTCP_DSS_ACK64; 1381 flags |= MPTCP_DSS_ACK64; 1382 } else { 1383 len += TCPOLEN_MPTCP_DSS_ACK32; 1384 } 1385 } 1386 1387 if (mpext->use_map) { 1388 len += TCPOLEN_MPTCP_DSS_MAP64; 1389 1390 /* Use only 64-bit mapping flags for now, add 1391 * support for optional 32-bit mappings later. 1392 */ 1393 flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64; 1394 if (mpext->data_fin) 1395 flags |= MPTCP_DSS_DATA_FIN; 1396 1397 if (opts->csum_reqd) 1398 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1399 } 1400 1401 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags); 1402 1403 if (mpext->use_ack) { 1404 if (mpext->ack64) { 1405 put_unaligned_be64(mpext->data_ack, ptr); 1406 ptr += 2; 1407 } else { 1408 put_unaligned_be32(mpext->data_ack32, ptr); 1409 ptr += 1; 1410 } 1411 } 1412 1413 if (mpext->use_map) { 1414 put_unaligned_be64(mpext->data_seq, ptr); 1415 ptr += 2; 1416 put_unaligned_be32(mpext->subflow_seq, ptr); 1417 ptr += 1; 1418 if (opts->csum_reqd) { 1419 /* data_len == 0 is reserved for the infinite mapping, 1420 * the checksum will also be set to 0. 1421 */ 1422 put_len_csum(mpext->data_len, 1423 (mpext->data_len ? mptcp_make_csum(mpext) : 0), 1424 ptr); 1425 } else { 1426 put_unaligned_be32(mpext->data_len << 16 | 1427 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1428 } 1429 ptr += 1; 1430 } 1431 1432 /* We might need to add MP_FAIL options in rare cases */ 1433 if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) 1434 goto mp_fail; 1435 } else if (OPTIONS_MPTCP_MPC & opts->suboptions) { 1436 u8 len, flag = MPTCP_CAP_HMAC_SHA256; 1437 1438 if (OPTION_MPTCP_MPC_SYN & opts->suboptions) { 1439 len = TCPOLEN_MPTCP_MPC_SYN; 1440 } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) { 1441 len = TCPOLEN_MPTCP_MPC_SYNACK; 1442 } else if (opts->data_len) { 1443 len = TCPOLEN_MPTCP_MPC_ACK_DATA; 1444 if (opts->csum_reqd) 1445 len += TCPOLEN_MPTCP_DSS_CHECKSUM; 1446 } else { 1447 len = TCPOLEN_MPTCP_MPC_ACK; 1448 } 1449 1450 if (opts->csum_reqd) 1451 flag |= MPTCP_CAP_CHECKSUM_REQD; 1452 1453 if (!opts->allow_join_id0) 1454 flag |= MPTCP_CAP_DENY_JOIN_ID0; 1455 1456 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len, 1457 MPTCP_SUPPORTED_VERSION, 1458 flag); 1459 1460 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) & 1461 opts->suboptions)) 1462 goto mp_capable_done; 1463 1464 put_unaligned_be64(opts->sndr_key, ptr); 1465 ptr += 2; 1466 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions)) 1467 goto mp_capable_done; 1468 1469 put_unaligned_be64(opts->rcvr_key, ptr); 1470 ptr += 2; 1471 if (!opts->data_len) 1472 goto mp_capable_done; 1473 1474 if (opts->csum_reqd) { 1475 put_len_csum(opts->data_len, 1476 __mptcp_make_csum(opts->data_seq, 1477 opts->subflow_seq, 1478 opts->data_len, 1479 ~csum_unfold(opts->csum)), 1480 ptr); 1481 } else { 1482 put_unaligned_be32(opts->data_len << 16 | 1483 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); 1484 } 1485 ptr += 1; 1486 1487 /* MPC is additionally mutually exclusive with MP_PRIO */ 1488 goto mp_capable_done; 1489 } else if (OPTIONS_MPTCP_MPJ & opts->suboptions) { 1490 if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) { 1491 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1492 TCPOLEN_MPTCP_MPJ_SYN, 1493 opts->backup, opts->join_id); 1494 put_unaligned_be32(opts->token, ptr); 1495 ptr += 1; 1496 put_unaligned_be32(opts->nonce, ptr); 1497 ptr += 1; 1498 } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) { 1499 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1500 TCPOLEN_MPTCP_MPJ_SYNACK, 1501 opts->backup, opts->join_id); 1502 put_unaligned_be64(opts->thmac, ptr); 1503 ptr += 2; 1504 put_unaligned_be32(opts->nonce, ptr); 1505 ptr += 1; 1506 } else { 1507 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, 1508 TCPOLEN_MPTCP_MPJ_ACK, 0, 0); 1509 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN); 1510 ptr += 5; 1511 } 1512 } else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) { 1513 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE; 1514 u8 echo = MPTCP_ADDR_ECHO; 1515 1516#if IS_ENABLED(CONFIG_MPTCP_IPV6) 1517 if (opts->addr.family == AF_INET6) 1518 len = TCPOLEN_MPTCP_ADD_ADDR6_BASE; 1519#endif 1520 1521 if (opts->addr.port) 1522 len += TCPOLEN_MPTCP_PORT_LEN; 1523 1524 if (opts->ahmac) { 1525 len += sizeof(opts->ahmac); 1526 echo = 0; 1527 } 1528 1529 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR, 1530 len, echo, opts->addr.id); 1531 if (opts->addr.family == AF_INET) { 1532 memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4); 1533 ptr += 1; 1534 } 1535#if IS_ENABLED(CONFIG_MPTCP_IPV6) 1536 else if (opts->addr.family == AF_INET6) { 1537 memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16); 1538 ptr += 4; 1539 } 1540#endif 1541 1542 if (!opts->addr.port) { 1543 if (opts->ahmac) { 1544 put_unaligned_be64(opts->ahmac, ptr); 1545 ptr += 2; 1546 } 1547 } else { 1548 u16 port = ntohs(opts->addr.port); 1549 1550 if (opts->ahmac) { 1551 u8 *bptr = (u8 *)ptr; 1552 1553 put_unaligned_be16(port, bptr); 1554 bptr += 2; 1555 put_unaligned_be64(opts->ahmac, bptr); 1556 bptr += 8; 1557 put_unaligned_be16(TCPOPT_NOP << 8 | 1558 TCPOPT_NOP, bptr); 1559 1560 ptr += 3; 1561 } else { 1562 put_unaligned_be32(port << 16 | 1563 TCPOPT_NOP << 8 | 1564 TCPOPT_NOP, ptr); 1565 ptr += 1; 1566 } 1567 } 1568 } else if (unlikely(OPTION_MPTCP_FASTCLOSE & opts->suboptions)) { 1569 /* FASTCLOSE is mutually exclusive with others except RST */ 1570 *ptr++ = mptcp_option(MPTCPOPT_MP_FASTCLOSE, 1571 TCPOLEN_MPTCP_FASTCLOSE, 1572 0, 0); 1573 put_unaligned_be64(opts->rcvr_key, ptr); 1574 ptr += 2; 1575 1576 if (OPTION_MPTCP_RST & opts->suboptions) 1577 goto mp_rst; 1578 return; 1579 } else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) { 1580mp_fail: 1581 /* MP_FAIL is mutually exclusive with others except RST */ 1582 subflow = mptcp_subflow_ctx(ssk); 1583 subflow->send_mp_fail = 0; 1584 1585 *ptr++ = mptcp_option(MPTCPOPT_MP_FAIL, 1586 TCPOLEN_MPTCP_FAIL, 1587 0, 0); 1588 put_unaligned_be64(opts->fail_seq, ptr); 1589 ptr += 2; 1590 1591 if (OPTION_MPTCP_RST & opts->suboptions) 1592 goto mp_rst; 1593 return; 1594 } else if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) { 1595mp_rst: 1596 *ptr++ = mptcp_option(MPTCPOPT_RST, 1597 TCPOLEN_MPTCP_RST, 1598 opts->reset_transient, 1599 opts->reset_reason); 1600 return; 1601 } 1602 1603 if (OPTION_MPTCP_PRIO & opts->suboptions) { 1604 subflow = mptcp_subflow_ctx(ssk); 1605 subflow->send_mp_prio = 0; 1606 1607 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO, 1608 TCPOLEN_MPTCP_PRIO, 1609 opts->backup, TCPOPT_NOP); 1610 1611 MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPPRIOTX); 1612 } 1613 1614mp_capable_done: 1615 if (OPTION_MPTCP_RM_ADDR & opts->suboptions) { 1616 u8 i = 1; 1617 1618 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR, 1619 TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr, 1620 0, opts->rm_list.ids[0]); 1621 1622 while (i < opts->rm_list.nr) { 1623 u8 id1, id2, id3, id4; 1624 1625 id1 = opts->rm_list.ids[i]; 1626 id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP; 1627 id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP; 1628 id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP; 1629 put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr); 1630 ptr += 1; 1631 i += 4; 1632 } 1633 } 1634 1635 if (tp) 1636 mptcp_set_rwin(tp, th); 1637} 1638 1639__be32 mptcp_get_reset_option(const struct sk_buff *skb) 1640{ 1641 const struct mptcp_ext *ext = mptcp_get_ext(skb); 1642 u8 flags, reason; 1643 1644 if (ext) { 1645 flags = ext->reset_transient; 1646 reason = ext->reset_reason; 1647 1648 return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST, 1649 flags, reason); 1650 } 1651 1652 return htonl(0u); 1653} 1654EXPORT_SYMBOL_GPL(mptcp_get_reset_option); 1655