net/mptcp/options.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Multipath TCP
   3  *
   4  * Copyright (c) 2017 - 2019, Intel Corporation.
   5  */
   6
   7 #define pr_fmt(fmt) "MPTCP: " fmt
   8
   9 #include <linux/kernel.h>
  10 #include <crypto/sha2.h>
  11 #include <net/tcp.h>
  12 #include <net/mptcp.h>
  13 #include "protocol.h"
  14 #include "mib.h"
  15
  16 #include <trace/events/mptcp.h>
  17
  18 static bool mptcp_cap_flag_sha256(u8 flags)
  19 {
  20         return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
  21 }
  22
  23 static void mptcp_parse_option(const struct sk_buff *skb,
  24                                const unsigned char *ptr, int opsize,
  25                                struct mptcp_options_received *mp_opt)
  26 {
  27         u8 subtype = *ptr >> 4;
  28         int expected_opsize;
  29         u8 version;
  30         u8 flags;
  31         u8 i;
  32
  33         switch (subtype) {
  34         case MPTCPOPT_MP_CAPABLE:
  35                 /* strict size checking */
  36                 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
  37                         if (skb->len > tcp_hdr(skb)->doff << 2)
  38                                 expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
  39                         else
  40                                 expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
  41                 } else {
  42                         if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
  43                                 expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
  44                         else
  45                                 expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
  46                 }
  47                 if (opsize != expected_opsize)
  48                         break;
  49
  50                 /* try to be gentle vs future versions on the initial syn */
  51                 version = *ptr++ & MPTCP_VERSION_MASK;
  52                 if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
  53                         if (version != MPTCP_SUPPORTED_VERSION)
  54                                 break;
  55                 } else if (version < MPTCP_SUPPORTED_VERSION) {
  56                         break;
  57                 }
  58
  59                 flags = *ptr++;
  60                 if (!mptcp_cap_flag_sha256(flags) ||
  61                     (flags & MPTCP_CAP_EXTENSIBILITY))
  62                         break;
  63
  64                 /* RFC 6824, Section 3.1:
  65                  * "For the Checksum Required bit (labeled "A"), if either
  66                  * host requires the use of checksums, checksums MUST be used.
  67                  * In other words, the only way for checksums not to be used
  68                  * is if both hosts in their SYNs set A=0."
  69                  *
  70                  * Section 3.3.0:
  71                  * "If a checksum is not present when its use has been
  72                  * negotiated, the receiver MUST close the subflow with a RST as
  73                  * it is considered broken."
  74                  *
  75                  * We don't implement DSS checksum - fall back to TCP.
  76                  */
  77                 if (flags & MPTCP_CAP_CHECKSUM_REQD)
  78                         break;
  79
  80                 mp_opt->mp_capable = 1;
  81                 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
  82                         mp_opt->sndr_key = get_unaligned_be64(ptr);
  83                         ptr += 8;
  84                 }
  85                 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
  86                         mp_opt->rcvr_key = get_unaligned_be64(ptr);
  87                         ptr += 8;
  88                 }
  89                 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA) {
  90                         /* Section 3.1.:
  91                          * "the data parameters in a MP_CAPABLE are semantically
  92                          * equivalent to those in a DSS option and can be used
  93                          * interchangeably."
  94                          */
  95                         mp_opt->dss = 1;
  96                         mp_opt->use_map = 1;
  97                         mp_opt->mpc_map = 1;
  98                         mp_opt->data_len = get_unaligned_be16(ptr);
  99                         ptr += 2;
 100                 }
 101                 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d",
 102                          version, flags, opsize, mp_opt->sndr_key,
 103                          mp_opt->rcvr_key, mp_opt->data_len);
 104                 break;
 105
 106         case MPTCPOPT_MP_JOIN:
 107                 mp_opt->mp_join = 1;
 108                 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
 109                         mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
 110                         mp_opt->join_id = *ptr++;
 111                         mp_opt->token = get_unaligned_be32(ptr);
 112                         ptr += 4;
 113                         mp_opt->nonce = get_unaligned_be32(ptr);
 114                         ptr += 4;
 115                         pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
 116                                  mp_opt->backup, mp_opt->join_id,
 117                                  mp_opt->token, mp_opt->nonce);
 118                 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) {
 119                         mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
 120                         mp_opt->join_id = *ptr++;
 121                         mp_opt->thmac = get_unaligned_be64(ptr);
 122                         ptr += 8;
 123                         mp_opt->nonce = get_unaligned_be32(ptr);
 124                         ptr += 4;
 125                         pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
 126                                  mp_opt->backup, mp_opt->join_id,
 127                                  mp_opt->thmac, mp_opt->nonce);
 128                 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
 129                         ptr += 2;
 130                         memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
 131                         pr_debug("MP_JOIN hmac");
 132                 } else {
 133                         mp_opt->mp_join = 0;
 134                 }
 135                 break;
 136
 137         case MPTCPOPT_DSS:
 138                 pr_debug("DSS");
 139                 ptr++;
 140
 141                 /* we must clear 'mpc_map' be able to detect MP_CAPABLE
 142                  * map vs DSS map in mptcp_incoming_options(), and reconstruct
 143                  * map info accordingly
 144                  */
 145                 mp_opt->mpc_map = 0;
 146                 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
 147                 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
 148                 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
 149                 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
 150                 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
 151                 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
 152
 153                 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
 154                          mp_opt->data_fin, mp_opt->dsn64,
 155                          mp_opt->use_map, mp_opt->ack64,
 156                          mp_opt->use_ack);
 157
 158                 expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
 159
 160                 if (mp_opt->use_ack) {
 161                         if (mp_opt->ack64)
 162                                 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
 163                         else
 164                                 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
 165                 }
 166
 167                 if (mp_opt->use_map) {
 168                         if (mp_opt->dsn64)
 169                                 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
 170                         else
 171                                 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
 172                 }
 173
 174                 /* RFC 6824, Section 3.3:
 175                  * If a checksum is present, but its use had
 176                  * not been negotiated in the MP_CAPABLE handshake,
 177                  * the checksum field MUST be ignored.
 178                  */
 179                 if (opsize != expected_opsize &&
 180                     opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
 181                         break;
 182
 183                 mp_opt->dss = 1;
 184
 185                 if (mp_opt->use_ack) {
 186                         if (mp_opt->ack64) {
 187                                 mp_opt->data_ack = get_unaligned_be64(ptr);
 188                                 ptr += 8;
 189                         } else {
 190                                 mp_opt->data_ack = get_unaligned_be32(ptr);
 191                                 ptr += 4;
 192                         }
 193
 194                         pr_debug("data_ack=%llu", mp_opt->data_ack);
 195                 }
 196
 197                 if (mp_opt->use_map) {
 198                         if (mp_opt->dsn64) {
 199                                 mp_opt->data_seq = get_unaligned_be64(ptr);
 200                                 ptr += 8;
 201                         } else {
 202                                 mp_opt->data_seq = get_unaligned_be32(ptr);
 203                                 ptr += 4;
 204                         }
 205
 206                         mp_opt->subflow_seq = get_unaligned_be32(ptr);
 207                         ptr += 4;
 208
 209                         mp_opt->data_len = get_unaligned_be16(ptr);
 210                         ptr += 2;
 211
 212                         pr_debug("data_seq=%llu subflow_seq=%u data_len=%u",
 213                                  mp_opt->data_seq, mp_opt->subflow_seq,
 214                                  mp_opt->data_len);
 215                 }
 216
 217                 break;
 218
 219         case MPTCPOPT_ADD_ADDR:
 220                 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
 221                 if (!mp_opt->echo) {
 222                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
 223                             opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
 224                                 mp_opt->addr.family = AF_INET;
 225 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 226                         else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
 227                                  opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
 228                                 mp_opt->addr.family = AF_INET6;
 229 #endif
 230                         else
 231                                 break;
 232                 } else {
 233                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
 234                             opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
 235                                 mp_opt->addr.family = AF_INET;
 236 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 237                         else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
 238                                  opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
 239                                 mp_opt->addr.family = AF_INET6;
 240 #endif
 241                         else
 242                                 break;
 243                 }
 244
 245                 mp_opt->add_addr = 1;
 246                 mp_opt->addr.id = *ptr++;
 247                 if (mp_opt->addr.family == AF_INET) {
 248                         memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4);
 249                         ptr += 4;
 250                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
 251                             opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
 252                                 mp_opt->addr.port = htons(get_unaligned_be16(ptr));
 253                                 ptr += 2;
 254                         }
 255                 }
 256 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 257                 else {
 258                         memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16);
 259                         ptr += 16;
 260                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
 261                             opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
 262                                 mp_opt->addr.port = htons(get_unaligned_be16(ptr));
 263                                 ptr += 2;
 264                         }
 265                 }
 266 #endif
 267                 if (!mp_opt->echo) {
 268                         mp_opt->ahmac = get_unaligned_be64(ptr);
 269                         ptr += 8;
 270                 }
 271                 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d",
 272                          (mp_opt->addr.family == AF_INET6) ? "6" : "",
 273                          mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port));
 274                 break;
 275
 276         case MPTCPOPT_RM_ADDR:
 277                 if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 ||
 278                     opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX)
 279                         break;
 280
 281                 ptr++;
 282
 283                 mp_opt->rm_addr = 1;
 284                 mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE;
 285                 for (i = 0; i < mp_opt->rm_list.nr; i++)
 286                         mp_opt->rm_list.ids[i] = *ptr++;
 287                 pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr);
 288                 break;
 289
 290         case MPTCPOPT_MP_PRIO:
 291                 if (opsize != TCPOLEN_MPTCP_PRIO)
 292                         break;
 293
 294                 mp_opt->mp_prio = 1;
 295                 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP;
 296                 pr_debug("MP_PRIO: prio=%d", mp_opt->backup);
 297                 break;
 298
 299         case MPTCPOPT_MP_FASTCLOSE:
 300                 if (opsize != TCPOLEN_MPTCP_FASTCLOSE)
 301                         break;
 302
 303                 ptr += 2;
 304                 mp_opt->rcvr_key = get_unaligned_be64(ptr);
 305                 ptr += 8;
 306                 mp_opt->fastclose = 1;
 307                 break;
 308
 309         case MPTCPOPT_RST:
 310                 if (opsize != TCPOLEN_MPTCP_RST)
 311                         break;
 312
 313                 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
 314                         break;
 315                 mp_opt->reset = 1;
 316                 flags = *ptr++;
 317                 mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT;
 318                 mp_opt->reset_reason = *ptr;
 319                 break;
 320
 321         default:
 322                 break;
 323         }
 324 }
 325
 326 void mptcp_get_options(const struct sk_buff *skb,
 327                        struct mptcp_options_received *mp_opt)
 328 {
 329         const struct tcphdr *th = tcp_hdr(skb);
 330         const unsigned char *ptr;
 331         int length;
 332
 333         /* initialize option status */
 334         mp_opt->mp_capable = 0;
 335         mp_opt->mp_join = 0;
 336         mp_opt->add_addr = 0;
 337         mp_opt->ahmac = 0;
 338         mp_opt->fastclose = 0;
 339         mp_opt->addr.port = 0;
 340         mp_opt->rm_addr = 0;
 341         mp_opt->dss = 0;
 342         mp_opt->mp_prio = 0;
 343         mp_opt->reset = 0;
 344
 345         length = (th->doff * 4) - sizeof(struct tcphdr);
 346         ptr = (const unsigned char *)(th + 1);
 347
 348         while (length > 0) {
 349                 int opcode = *ptr++;
 350                 int opsize;
 351
 352                 switch (opcode) {
 353                 case TCPOPT_EOL:
 354                         return;
 355                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 356                         length--;
 357                         continue;
 358                 default:
 359                         opsize = *ptr++;
 360                         if (opsize < 2) /* "silly options" */
 361                                 return;
 362                         if (opsize > length)
 363                                 return; /* don't parse partial options */
 364                         if (opcode == TCPOPT_MPTCP)
 365                                 mptcp_parse_option(skb, ptr, opsize, mp_opt);
 366                         ptr += opsize - 2;
 367                         length -= opsize;
 368                 }
 369         }
 370 }
 371
 372 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 373                        unsigned int *size, struct mptcp_out_options *opts)
 374 {
 375         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 376
 377         /* we will use snd_isn to detect first pkt [re]transmission
 378          * in mptcp_established_options_mp()
 379          */
 380         subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
 381         if (subflow->request_mptcp) {
 382                 opts->suboptions = OPTION_MPTCP_MPC_SYN;
 383                 *size = TCPOLEN_MPTCP_MPC_SYN;
 384                 return true;
 385         } else if (subflow->request_join) {
 386                 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
 387                          subflow->local_nonce);
 388                 opts->suboptions = OPTION_MPTCP_MPJ_SYN;
 389                 opts->join_id = subflow->local_id;
 390                 opts->token = subflow->remote_token;
 391                 opts->nonce = subflow->local_nonce;
 392                 opts->backup = subflow->request_bkup;
 393                 *size = TCPOLEN_MPTCP_MPJ_SYN;
 394                 return true;
 395         }
 396         return false;
 397 }
 398
 399 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
 400  * TCP can't schedule delack timer before the subflow is fully established.
 401  * MPTCP uses the delack timer to do 3rd ack retransmissions
 402  */
 403 static void schedule_3rdack_retransmission(struct sock *sk)
 404 {
 405         struct inet_connection_sock *icsk = inet_csk(sk);
 406         struct tcp_sock *tp = tcp_sk(sk);
 407         unsigned long timeout;
 408
 409         /* reschedule with a timeout above RTT, as we must look only for drop */
 410         if (tp->srtt_us)
 411                 timeout = tp->srtt_us << 1;
 412         else
 413                 timeout = TCP_TIMEOUT_INIT;
 414
 415         WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
 416         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 417         icsk->icsk_ack.timeout = timeout;
 418         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 419 }
 420
 421 static void clear_3rdack_retransmission(struct sock *sk)
 422 {
 423         struct inet_connection_sock *icsk = inet_csk(sk);
 424
 425         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 426         icsk->icsk_ack.timeout = 0;
 427         icsk->icsk_ack.ato = 0;
 428         icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
 429 }
 430
 431 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 432                                          bool snd_data_fin_enable,
 433                                          unsigned int *size,
 434                                          unsigned int remaining,
 435                                          struct mptcp_out_options *opts)
 436 {
 437         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 438         struct mptcp_ext *mpext;
 439         unsigned int data_len;
 440
 441         /* When skb is not available, we better over-estimate the emitted
 442          * options len. A full DSS option (28 bytes) is longer than
 443          * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
 444          * tell the caller to defer the estimate to
 445          * mptcp_established_options_dss(), which will reserve enough space.
 446          */
 447         if (!skb)
 448                 return false;
 449
 450         /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */
 451         if (subflow->fully_established || snd_data_fin_enable ||
 452             subflow->snd_isn != TCP_SKB_CB(skb)->seq ||
 453             sk->sk_state != TCP_ESTABLISHED)
 454                 return false;
 455
 456         if (subflow->mp_capable) {
 457                 mpext = mptcp_get_ext(skb);
 458                 data_len = mpext ? mpext->data_len : 0;
 459
 460                 /* we will check ext_copy.data_len in mptcp_write_options() to
 461                  * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
 462                  * TCPOLEN_MPTCP_MPC_ACK
 463                  */
 464                 opts->ext_copy.data_len = data_len;
 465                 opts->suboptions = OPTION_MPTCP_MPC_ACK;
 466                 opts->sndr_key = subflow->local_key;
 467                 opts->rcvr_key = subflow->remote_key;
 468
 469                 /* Section 3.1.
 470                  * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
 471                  * packets that start the first subflow of an MPTCP connection,
 472                  * as well as the first packet that carries data
 473                  */
 474                 if (data_len > 0)
 475                         *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
 476                 else
 477                         *size = TCPOLEN_MPTCP_MPC_ACK;
 478
 479                 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
 480                          subflow, subflow->local_key, subflow->remote_key,
 481                          data_len);
 482
 483                 return true;
 484         } else if (subflow->mp_join) {
 485                 opts->suboptions = OPTION_MPTCP_MPJ_ACK;
 486                 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
 487                 *size = TCPOLEN_MPTCP_MPJ_ACK;
 488                 pr_debug("subflow=%p", subflow);
 489
 490                 schedule_3rdack_retransmission(sk);
 491                 return true;
 492         }
 493         return false;
 494 }
 495
 496 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
 497                                  struct sk_buff *skb, struct mptcp_ext *ext)
 498 {
 499         /* The write_seq value has already been incremented, so the actual
 500          * sequence number for the DATA_FIN is one less.
 501          */
 502         u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
 503
 504         if (!ext->use_map || !skb->len) {
 505                 /* RFC6824 requires a DSS mapping with specific values
 506                  * if DATA_FIN is set but no data payload is mapped
 507                  */
 508                 ext->data_fin = 1;
 509                 ext->use_map = 1;
 510                 ext->dsn64 = 1;
 511                 ext->data_seq = data_fin_tx_seq;
 512                 ext->subflow_seq = 0;
 513                 ext->data_len = 1;
 514         } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
 515                 /* If there's an existing DSS mapping and it is the
 516                  * final mapping, DATA_FIN consumes 1 additional byte of
 517                  * mapping space.
 518                  */
 519                 ext->data_fin = 1;
 520                 ext->data_len++;
 521         }
 522 }
 523
 524 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 525                                           bool snd_data_fin_enable,
 526                                           unsigned int *size,
 527                                           unsigned int remaining,
 528                                           struct mptcp_out_options *opts)
 529 {
 530         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 531         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 532         unsigned int dss_size = 0;
 533         struct mptcp_ext *mpext;
 534         unsigned int ack_size;
 535         bool ret = false;
 536         u64 ack_seq;
 537
 538         mpext = skb ? mptcp_get_ext(skb) : NULL;
 539
 540         if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
 541                 unsigned int map_size;
 542
 543                 map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
 544
 545                 remaining -= map_size;
 546                 dss_size = map_size;
 547                 if (mpext)
 548                         opts->ext_copy = *mpext;
 549
 550                 if (skb && snd_data_fin_enable)
 551                         mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
 552                 ret = true;
 553         }
 554
 555         /* passive sockets msk will set the 'can_ack' after accept(), even
 556          * if the first subflow may have the already the remote key handy
 557          */
 558         opts->ext_copy.use_ack = 0;
 559         if (!READ_ONCE(msk->can_ack)) {
 560                 *size = ALIGN(dss_size, 4);
 561                 return ret;
 562         }
 563
 564         ack_seq = READ_ONCE(msk->ack_seq);
 565         if (READ_ONCE(msk->use_64bit_ack)) {
 566                 ack_size = TCPOLEN_MPTCP_DSS_ACK64;
 567                 opts->ext_copy.data_ack = ack_seq;
 568                 opts->ext_copy.ack64 = 1;
 569         } else {
 570                 ack_size = TCPOLEN_MPTCP_DSS_ACK32;
 571                 opts->ext_copy.data_ack32 = (uint32_t)ack_seq;
 572                 opts->ext_copy.ack64 = 0;
 573         }
 574         opts->ext_copy.use_ack = 1;
 575         WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
 576
 577         /* Add kind/length/subtype/flag overhead if mapping is not populated */
 578         if (dss_size == 0)
 579                 ack_size += TCPOLEN_MPTCP_DSS_BASE;
 580
 581         dss_size += ack_size;
 582
 583         *size = ALIGN(dss_size, 4);
 584         return true;
 585 }
 586
 587 static u64 add_addr_generate_hmac(u64 key1, u64 key2,
 588                                   struct mptcp_addr_info *addr)
 589 {
 590         u16 port = ntohs(addr->port);
 591         u8 hmac[SHA256_DIGEST_SIZE];
 592         u8 msg[19];
 593         int i = 0;
 594
 595         msg[i++] = addr->id;
 596         if (addr->family == AF_INET) {
 597                 memcpy(&msg[i], &addr->addr.s_addr, 4);
 598                 i += 4;
 599         }
 600 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 601         else if (addr->family == AF_INET6) {
 602                 memcpy(&msg[i], &addr->addr6.s6_addr, 16);
 603                 i += 16;
 604         }
 605 #endif
 606         msg[i++] = port >> 8;
 607         msg[i++] = port & 0xFF;
 608
 609         mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac);
 610
 611         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 612 }
 613
 614 static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb,
 615                                                unsigned int *size,
 616                                                unsigned int remaining,
 617                                                struct mptcp_out_options *opts)
 618 {
 619         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 620         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 621         bool drop_other_suboptions = false;
 622         unsigned int opt_size = *size;
 623         bool echo;
 624         bool port;
 625         int len;
 626
 627         if ((mptcp_pm_should_add_signal_ipv6(msk) ||
 628              mptcp_pm_should_add_signal_port(msk) ||
 629              mptcp_pm_should_add_signal_echo(msk)) &&
 630             skb && skb_is_tcp_pure_ack(skb)) {
 631                 pr_debug("drop other suboptions");
 632                 opts->suboptions = 0;
 633                 opts->ext_copy.use_ack = 0;
 634                 opts->ext_copy.use_map = 0;
 635                 remaining += opt_size;
 636                 drop_other_suboptions = true;
 637         }
 638
 639         if (!mptcp_pm_should_add_signal(msk) ||
 640             !(mptcp_pm_add_addr_signal(msk, remaining, &opts->addr, &echo, &port)))
 641                 return false;
 642
 643         len = mptcp_add_addr_len(opts->addr.family, echo, port);
 644         if (remaining < len)
 645                 return false;
 646
 647         *size = len;
 648         if (drop_other_suboptions)
 649                 *size -= opt_size;
 650         opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
 651         if (!echo) {
 652                 opts->ahmac = add_addr_generate_hmac(msk->local_key,
 653                                                      msk->remote_key,
 654                                                      &opts->addr);
 655         }
 656         pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
 657                  opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port));
 658
 659         return true;
 660 }
 661
 662 static bool mptcp_established_options_rm_addr(struct sock *sk,
 663                                               unsigned int *size,
 664                                               unsigned int remaining,
 665                                               struct mptcp_out_options *opts)
 666 {
 667         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 668         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 669         struct mptcp_rm_list rm_list;
 670         int i, len;
 671
 672         if (!mptcp_pm_should_rm_signal(msk) ||
 673             !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list)))
 674                 return false;
 675
 676         len = mptcp_rm_addr_len(&rm_list);
 677         if (len < 0)
 678                 return false;
 679         if (remaining < len)
 680                 return false;
 681
 682         *size = len;
 683         opts->suboptions |= OPTION_MPTCP_RM_ADDR;
 684         opts->rm_list = rm_list;
 685
 686         for (i = 0; i < opts->rm_list.nr; i++)
 687                 pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]);
 688
 689         return true;
 690 }
 691
 692 static bool mptcp_established_options_mp_prio(struct sock *sk,
 693                                               unsigned int *size,
 694                                               unsigned int remaining,
 695                                               struct mptcp_out_options *opts)
 696 {
 697         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 698
 699         if (!subflow->send_mp_prio)
 700                 return false;
 701
 702         /* account for the trailing 'nop' option */
 703         if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN)
 704                 return false;
 705
 706         *size = TCPOLEN_MPTCP_PRIO_ALIGN;
 707         opts->suboptions |= OPTION_MPTCP_PRIO;
 708         opts->backup = subflow->request_bkup;
 709
 710         pr_debug("prio=%d", opts->backup);
 711
 712         return true;
 713 }
 714
 715 static noinline void mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
 716                                                    unsigned int *size,
 717                                                    unsigned int remaining,
 718                                                    struct mptcp_out_options *opts)
 719 {
 720         const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 721
 722         if (remaining < TCPOLEN_MPTCP_RST)
 723                 return;
 724
 725         *size = TCPOLEN_MPTCP_RST;
 726         opts->suboptions |= OPTION_MPTCP_RST;
 727         opts->reset_transient = subflow->reset_transient;
 728         opts->reset_reason = subflow->reset_reason;
 729 }
 730
 731 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 732                                unsigned int *size, unsigned int remaining,
 733                                struct mptcp_out_options *opts)
 734 {
 735         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 736         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 737         unsigned int opt_size = 0;
 738         bool snd_data_fin;
 739         bool ret = false;
 740
 741         opts->suboptions = 0;
 742
 743         if (unlikely(__mptcp_check_fallback(msk)))
 744                 return false;
 745
 746         if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
 747                 mptcp_established_options_rst(sk, skb, size, remaining, opts);
 748                 return true;
 749         }
 750
 751         snd_data_fin = mptcp_data_fin_enabled(msk);
 752         if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, remaining, opts))
 753                 ret = true;
 754         else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, remaining, opts))
 755                 ret = true;
 756
 757         /* we reserved enough space for the above options, and exceeding the
 758          * TCP option space would be fatal
 759          */
 760         if (WARN_ON_ONCE(opt_size > remaining))
 761                 return false;
 762
 763         *size += opt_size;
 764         remaining -= opt_size;
 765         if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
 766                 *size += opt_size;
 767                 remaining -= opt_size;
 768                 ret = true;
 769         } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
 770                 *size += opt_size;
 771                 remaining -= opt_size;
 772                 ret = true;
 773         }
 774
 775         if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) {
 776                 *size += opt_size;
 777                 remaining -= opt_size;
 778                 ret = true;
 779         }
 780
 781         return ret;
 782 }
 783
 784 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 785                           struct mptcp_out_options *opts)
 786 {
 787         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 788
 789         if (subflow_req->mp_capable) {
 790                 opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
 791                 opts->sndr_key = subflow_req->local_key;
 792                 *size = TCPOLEN_MPTCP_MPC_SYNACK;
 793                 pr_debug("subflow_req=%p, local_key=%llu",
 794                          subflow_req, subflow_req->local_key);
 795                 return true;
 796         } else if (subflow_req->mp_join) {
 797                 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
 798                 opts->backup = subflow_req->backup;
 799                 opts->join_id = subflow_req->local_id;
 800                 opts->thmac = subflow_req->thmac;
 801                 opts->nonce = subflow_req->local_nonce;
 802                 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
 803                          subflow_req, opts->backup, opts->join_id,
 804                          opts->thmac, opts->nonce);
 805                 *size = TCPOLEN_MPTCP_MPJ_SYNACK;
 806                 return true;
 807         }
 808         return false;
 809 }
 810
 811 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
 812                                     struct mptcp_subflow_context *subflow,
 813                                     struct sk_buff *skb,
 814                                     struct mptcp_options_received *mp_opt)
 815 {
 816         /* here we can process OoO, in-window pkts, only in-sequence 4th ack
 817          * will make the subflow fully established
 818          */
 819         if (likely(subflow->fully_established)) {
 820                 /* on passive sockets, check for 3rd ack retransmission
 821                  * note that msk is always set by subflow_syn_recv_sock()
 822                  * for mp_join subflows
 823                  */
 824                 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
 825                     TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
 826                     subflow->mp_join && mp_opt->mp_join &&
 827                     READ_ONCE(msk->pm.server_side))
 828                         tcp_send_ack(ssk);
 829                 goto fully_established;
 830         }
 831
 832         /* we must process OoO packets before the first subflow is fully
 833          * established. OoO packets are instead a protocol violation
 834          * for MP_JOIN subflows as the peer must not send any data
 835          * before receiving the forth ack - cfr. RFC 8684 section 3.2.
 836          */
 837         if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
 838                 if (subflow->mp_join)
 839                         goto reset;
 840                 return subflow->mp_capable;
 841         }
 842
 843         if (mp_opt->dss && mp_opt->use_ack) {
 844                 /* subflows are fully established as soon as we get any
 845                  * additional ack.
 846                  */
 847                 subflow->fully_established = 1;
 848                 WRITE_ONCE(msk->fully_established, true);
 849                 goto fully_established;
 850         }
 851
 852         if (mp_opt->add_addr) {
 853                 WRITE_ONCE(msk->fully_established, true);
 854                 return true;
 855         }
 856
 857         /* If the first established packet does not contain MP_CAPABLE + data
 858          * then fallback to TCP. Fallback scenarios requires a reset for
 859          * MP_JOIN subflows.
 860          */
 861         if (!mp_opt->mp_capable) {
 862                 if (subflow->mp_join)
 863                         goto reset;
 864                 subflow->mp_capable = 0;
 865                 pr_fallback(msk);
 866                 __mptcp_do_fallback(msk);
 867                 return false;
 868         }
 869
 870         if (unlikely(!READ_ONCE(msk->pm.server_side)))
 871                 pr_warn_once("bogus mpc option on established client sk");
 872         mptcp_subflow_fully_established(subflow, mp_opt);
 873
 874 fully_established:
 875         /* if the subflow is not already linked into the conn_list, we can't
 876          * notify the PM: this subflow is still on the listener queue
 877          * and the PM possibly acquiring the subflow lock could race with
 878          * the listener close
 879          */
 880         if (likely(subflow->pm_notified) || list_empty(&subflow->node))
 881                 return true;
 882
 883         subflow->pm_notified = 1;
 884         if (subflow->mp_join) {
 885                 clear_3rdack_retransmission(ssk);
 886                 mptcp_pm_subflow_established(msk);
 887         } else {
 888                 mptcp_pm_fully_established(msk, ssk, GFP_ATOMIC);
 889         }
 890         return true;
 891
 892 reset:
 893         mptcp_subflow_reset(ssk);
 894         return false;
 895 }
 896
 897 static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
 898 {
 899         u32 old_ack32, cur_ack32;
 900
 901         if (use_64bit)
 902                 return cur_ack;
 903
 904         old_ack32 = (u32)old_ack;
 905         cur_ack32 = (u32)cur_ack;
 906         cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
 907         if (unlikely(before(cur_ack32, old_ack32)))
 908                 return cur_ack + (1LL << 32);
 909         return cur_ack;
 910 }
 911
 912 static void ack_update_msk(struct mptcp_sock *msk,
 913                            struct sock *ssk,
 914                            struct mptcp_options_received *mp_opt)
 915 {
 916         u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt);
 917         struct sock *sk = (struct sock *)msk;
 918         u64 old_snd_una;
 919
 920         mptcp_data_lock(sk);
 921
 922         /* avoid ack expansion on update conflict, to reduce the risk of
 923          * wrongly expanding to a future ack sequence number, which is way
 924          * more dangerous than missing an ack
 925          */
 926         old_snd_una = msk->snd_una;
 927         new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
 928
 929         /* ACK for data not even sent yet? Ignore. */
 930         if (after64(new_snd_una, snd_nxt))
 931                 new_snd_una = old_snd_una;
 932
 933         new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
 934
 935         if (after64(new_wnd_end, msk->wnd_end))
 936                 msk->wnd_end = new_wnd_end;
 937
 938         /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
 939         if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)))
 940                 __mptcp_check_push(sk, ssk);
 941
 942         if (after64(new_snd_una, old_snd_una)) {
 943                 msk->snd_una = new_snd_una;
 944                 __mptcp_data_acked(sk);
 945         }
 946         mptcp_data_unlock(sk);
 947
 948         trace_ack_update_msk(mp_opt->data_ack,
 949                              old_snd_una, new_snd_una,
 950                              new_wnd_end, msk->wnd_end);
 951 }
 952
 953 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
 954 {
 955         /* Skip if DATA_FIN was already received.
 956          * If updating simultaneously with the recvmsg loop, values
 957          * should match. If they mismatch, the peer is misbehaving and
 958          * we will prefer the most recent information.
 959          */
 960         if (READ_ONCE(msk->rcv_data_fin))
 961                 return false;
 962
 963         WRITE_ONCE(msk->rcv_data_fin_seq,
 964                    expand_ack(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
 965         WRITE_ONCE(msk->rcv_data_fin, 1);
 966
 967         return true;
 968 }
 969
 970 static bool add_addr_hmac_valid(struct mptcp_sock *msk,
 971                                 struct mptcp_options_received *mp_opt)
 972 {
 973         u64 hmac = 0;
 974
 975         if (mp_opt->echo)
 976                 return true;
 977
 978         hmac = add_addr_generate_hmac(msk->remote_key,
 979                                       msk->local_key,
 980                                       &mp_opt->addr);
 981
 982         pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
 983                  msk, (unsigned long long)hmac,
 984                  (unsigned long long)mp_opt->ahmac);
 985
 986         return hmac == mp_opt->ahmac;
 987 }
 988
 989 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 990 {
 991         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 992         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 993         struct mptcp_options_received mp_opt;
 994         struct mptcp_ext *mpext;
 995
 996         if (__mptcp_check_fallback(msk)) {
 997                 /* Keep it simple and unconditionally trigger send data cleanup and
 998                  * pending queue spooling. We will need to acquire the data lock
 999                  * for more accurate checks, and once the lock is acquired, such
1000                  * helpers are cheap.
1001                  */
1002                 mptcp_data_lock(subflow->conn);
1003                 if (sk_stream_memory_free(sk))
1004                         __mptcp_check_push(subflow->conn, sk);
1005                 __mptcp_data_acked(subflow->conn);
1006                 mptcp_data_unlock(subflow->conn);
1007                 return;
1008         }
1009
1010         mptcp_get_options(skb, &mp_opt);
1011         if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
1012                 return;
1013
1014         if (mp_opt.fastclose &&
1015             msk->local_key == mp_opt.rcvr_key) {
1016                 WRITE_ONCE(msk->rcv_fastclose, true);
1017                 mptcp_schedule_work((struct sock *)msk);
1018         }
1019
1020         if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
1021                 if (!mp_opt.echo) {
1022                         mptcp_pm_add_addr_received(msk, &mp_opt.addr);
1023                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
1024                 } else {
1025                         mptcp_pm_add_addr_echoed(msk, &mp_opt.addr);
1026                         mptcp_pm_del_add_timer(msk, &mp_opt.addr, true);
1027                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
1028                 }
1029
1030                 if (mp_opt.addr.port)
1031                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD);
1032
1033                 mp_opt.add_addr = 0;
1034         }
1035
1036         if (mp_opt.rm_addr) {
1037                 mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list);
1038                 mp_opt.rm_addr = 0;
1039         }
1040
1041         if (mp_opt.mp_prio) {
1042                 mptcp_pm_mp_prio_received(sk, mp_opt.backup);
1043                 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX);
1044                 mp_opt.mp_prio = 0;
1045         }
1046
1047         if (mp_opt.reset) {
1048                 subflow->reset_seen = 1;
1049                 subflow->reset_reason = mp_opt.reset_reason;
1050                 subflow->reset_transient = mp_opt.reset_transient;
1051         }
1052
1053         if (!mp_opt.dss)
1054                 return;
1055
1056         /* we can't wait for recvmsg() to update the ack_seq, otherwise
1057          * monodirectional flows will stuck
1058          */
1059         if (mp_opt.use_ack)
1060                 ack_update_msk(msk, sk, &mp_opt);
1061
1062         /* Zero-data-length packets are dropped by the caller and not
1063          * propagated to the MPTCP layer, so the skb extension does not
1064          * need to be allocated or populated. DATA_FIN information, if
1065          * present, needs to be updated here before the skb is freed.
1066          */
1067         if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
1068                 if (mp_opt.data_fin && mp_opt.data_len == 1 &&
1069                     mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
1070                     schedule_work(&msk->work))
1071                         sock_hold(subflow->conn);
1072
1073                 return;
1074         }
1075
1076         mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
1077         if (!mpext)
1078                 return;
1079
1080         memset(mpext, 0, sizeof(*mpext));
1081
1082         if (mp_opt.use_map) {
1083                 if (mp_opt.mpc_map) {
1084                         /* this is an MP_CAPABLE carrying MPTCP data
1085                          * we know this map the first chunk of data
1086                          */
1087                         mptcp_crypto_key_sha(subflow->remote_key, NULL,
1088                                              &mpext->data_seq);
1089                         mpext->data_seq++;
1090                         mpext->subflow_seq = 1;
1091                         mpext->dsn64 = 1;
1092                         mpext->mpc_map = 1;
1093                         mpext->data_fin = 0;
1094                 } else {
1095                         mpext->data_seq = mp_opt.data_seq;
1096                         mpext->subflow_seq = mp_opt.subflow_seq;
1097                         mpext->dsn64 = mp_opt.dsn64;
1098                         mpext->data_fin = mp_opt.data_fin;
1099                 }
1100                 mpext->data_len = mp_opt.data_len;
1101                 mpext->use_map = 1;
1102         }
1103 }
1104
1105 static void mptcp_set_rwin(const struct tcp_sock *tp)
1106 {
1107         const struct sock *ssk = (const struct sock *)tp;
1108         const struct mptcp_subflow_context *subflow;
1109         struct mptcp_sock *msk;
1110         u64 ack_seq;
1111
1112         subflow = mptcp_subflow_ctx(ssk);
1113         msk = mptcp_sk(subflow->conn);
1114
1115         ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd;
1116
1117         if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent)))
1118                 WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
1119 }
1120
1121 void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
1122                          struct mptcp_out_options *opts)
1123 {
1124         if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
1125              OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
1126                 u8 len;
1127
1128                 if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
1129                         len = TCPOLEN_MPTCP_MPC_SYN;
1130                 else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
1131                         len = TCPOLEN_MPTCP_MPC_SYNACK;
1132                 else if (opts->ext_copy.data_len)
1133                         len = TCPOLEN_MPTCP_MPC_ACK_DATA;
1134                 else
1135                         len = TCPOLEN_MPTCP_MPC_ACK;
1136
1137                 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
1138                                       MPTCP_SUPPORTED_VERSION,
1139                                       MPTCP_CAP_HMAC_SHA256);
1140
1141                 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
1142                     opts->suboptions))
1143                         goto mp_capable_done;
1144
1145                 put_unaligned_be64(opts->sndr_key, ptr);
1146                 ptr += 2;
1147                 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1148                         goto mp_capable_done;
1149
1150                 put_unaligned_be64(opts->rcvr_key, ptr);
1151                 ptr += 2;
1152                 if (!opts->ext_copy.data_len)
1153                         goto mp_capable_done;
1154
1155                 put_unaligned_be32(opts->ext_copy.data_len << 16 |
1156                                    TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1157                 ptr += 1;
1158         }
1159
1160 mp_capable_done:
1161         if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
1162                 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
1163                 u8 echo = MPTCP_ADDR_ECHO;
1164
1165 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1166                 if (opts->addr.family == AF_INET6)
1167                         len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
1168 #endif
1169
1170                 if (opts->addr.port)
1171                         len += TCPOLEN_MPTCP_PORT_LEN;
1172
1173                 if (opts->ahmac) {
1174                         len += sizeof(opts->ahmac);
1175                         echo = 0;
1176                 }
1177
1178                 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1179                                       len, echo, opts->addr.id);
1180                 if (opts->addr.family == AF_INET) {
1181                         memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4);
1182                         ptr += 1;
1183                 }
1184 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1185                 else if (opts->addr.family == AF_INET6) {
1186                         memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16);
1187                         ptr += 4;
1188                 }
1189 #endif
1190
1191                 if (!opts->addr.port) {
1192                         if (opts->ahmac) {
1193                                 put_unaligned_be64(opts->ahmac, ptr);
1194                                 ptr += 2;
1195                         }
1196                 } else {
1197                         u16 port = ntohs(opts->addr.port);
1198
1199                         if (opts->ahmac) {
1200                                 u8 *bptr = (u8 *)ptr;
1201
1202                                 put_unaligned_be16(port, bptr);
1203                                 bptr += 2;
1204                                 put_unaligned_be64(opts->ahmac, bptr);
1205                                 bptr += 8;
1206                                 put_unaligned_be16(TCPOPT_NOP << 8 |
1207                                                    TCPOPT_NOP, bptr);
1208
1209                                 ptr += 3;
1210                         } else {
1211                                 put_unaligned_be32(port << 16 |
1212                                                    TCPOPT_NOP << 8 |
1213                                                    TCPOPT_NOP, ptr);
1214                                 ptr += 1;
1215                         }
1216                 }
1217         }
1218
1219         if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1220                 u8 i = 1;
1221
1222                 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1223                                       TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr,
1224                                       0, opts->rm_list.ids[0]);
1225
1226                 while (i < opts->rm_list.nr) {
1227                         u8 id1, id2, id3, id4;
1228
1229                         id1 = opts->rm_list.ids[i];
1230                         id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP;
1231                         id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP;
1232                         id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP;
1233                         put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr);
1234                         ptr += 1;
1235                         i += 4;
1236                 }
1237         }
1238
1239         if (OPTION_MPTCP_PRIO & opts->suboptions) {
1240                 const struct sock *ssk = (const struct sock *)tp;
1241                 struct mptcp_subflow_context *subflow;
1242
1243                 subflow = mptcp_subflow_ctx(ssk);
1244                 subflow->send_mp_prio = 0;
1245
1246                 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
1247                                       TCPOLEN_MPTCP_PRIO,
1248                                       opts->backup, TCPOPT_NOP);
1249         }
1250
1251         if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1252                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1253                                       TCPOLEN_MPTCP_MPJ_SYN,
1254                                       opts->backup, opts->join_id);
1255                 put_unaligned_be32(opts->token, ptr);
1256                 ptr += 1;
1257                 put_unaligned_be32(opts->nonce, ptr);
1258                 ptr += 1;
1259         }
1260
1261         if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1262                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1263                                       TCPOLEN_MPTCP_MPJ_SYNACK,
1264                                       opts->backup, opts->join_id);
1265                 put_unaligned_be64(opts->thmac, ptr);
1266                 ptr += 2;
1267                 put_unaligned_be32(opts->nonce, ptr);
1268                 ptr += 1;
1269         }
1270
1271         if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1272                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1273                                       TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1274                 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1275                 ptr += 5;
1276         }
1277
1278         if (OPTION_MPTCP_RST & opts->suboptions)
1279                 *ptr++ = mptcp_option(MPTCPOPT_RST,
1280                                       TCPOLEN_MPTCP_RST,
1281                                       opts->reset_transient,
1282                                       opts->reset_reason);
1283
1284         if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
1285                 struct mptcp_ext *mpext = &opts->ext_copy;
1286                 u8 len = TCPOLEN_MPTCP_DSS_BASE;
1287                 u8 flags = 0;
1288
1289                 if (mpext->use_ack) {
1290                         flags = MPTCP_DSS_HAS_ACK;
1291                         if (mpext->ack64) {
1292                                 len += TCPOLEN_MPTCP_DSS_ACK64;
1293                                 flags |= MPTCP_DSS_ACK64;
1294                         } else {
1295                                 len += TCPOLEN_MPTCP_DSS_ACK32;
1296                         }
1297                 }
1298
1299                 if (mpext->use_map) {
1300                         len += TCPOLEN_MPTCP_DSS_MAP64;
1301
1302                         /* Use only 64-bit mapping flags for now, add
1303                          * support for optional 32-bit mappings later.
1304                          */
1305                         flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1306                         if (mpext->data_fin)
1307                                 flags |= MPTCP_DSS_DATA_FIN;
1308                 }
1309
1310                 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
1311
1312                 if (mpext->use_ack) {
1313                         if (mpext->ack64) {
1314                                 put_unaligned_be64(mpext->data_ack, ptr);
1315                                 ptr += 2;
1316                         } else {
1317                                 put_unaligned_be32(mpext->data_ack32, ptr);
1318                                 ptr += 1;
1319                         }
1320                 }
1321
1322                 if (mpext->use_map) {
1323                         put_unaligned_be64(mpext->data_seq, ptr);
1324                         ptr += 2;
1325                         put_unaligned_be32(mpext->subflow_seq, ptr);
1326                         ptr += 1;
1327                         put_unaligned_be32(mpext->data_len << 16 |
1328                                            TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1329                 }
1330         }
1331
1332         if (tp)
1333                 mptcp_set_rwin(tp);
1334 }
1335
1336 __be32 mptcp_get_reset_option(const struct sk_buff *skb)
1337 {
1338         const struct mptcp_ext *ext = mptcp_get_ext(skb);
1339         u8 flags, reason;
1340
1341         if (ext) {
1342                 flags = ext->reset_transient;
1343                 reason = ext->reset_reason;
1344
1345                 return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST,
1346                                     flags, reason);
1347         }
1348
1349         return htonl(0u);
1350 }
1351 EXPORT_SYMBOL_GPL(mptcp_get_reset_option);