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/sha.h>
  11 #include <net/tcp.h>
  12 #include <net/mptcp.h>
  13 #include "protocol.h"
  14 #include "mib.h"
  15
  16 static bool mptcp_cap_flag_sha256(u8 flags)
  17 {
  18         return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
  19 }
  20
  21 static void mptcp_parse_option(const struct sk_buff *skb,
  22                                const unsigned char *ptr, int opsize,
  23                                struct mptcp_options_received *mp_opt)
  24 {
  25         u8 subtype = *ptr >> 4;
  26         int expected_opsize;
  27         u8 version;
  28         u8 flags;
  29
  30         switch (subtype) {
  31         case MPTCPOPT_MP_CAPABLE:
  32                 /* strict size checking */
  33                 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
  34                         if (skb->len > tcp_hdr(skb)->doff << 2)
  35                                 expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
  36                         else
  37                                 expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
  38                 } else {
  39                         if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
  40                                 expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
  41                         else
  42                                 expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
  43                 }
  44                 if (opsize != expected_opsize)
  45                         break;
  46
  47                 /* try to be gentle vs future versions on the initial syn */
  48                 version = *ptr++ & MPTCP_VERSION_MASK;
  49                 if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
  50                         if (version != MPTCP_SUPPORTED_VERSION)
  51                                 break;
  52                 } else if (version < MPTCP_SUPPORTED_VERSION) {
  53                         break;
  54                 }
  55
  56                 flags = *ptr++;
  57                 if (!mptcp_cap_flag_sha256(flags) ||
  58                     (flags & MPTCP_CAP_EXTENSIBILITY))
  59                         break;
  60
  61                 /* RFC 6824, Section 3.1:
  62                  * "For the Checksum Required bit (labeled "A"), if either
  63                  * host requires the use of checksums, checksums MUST be used.
  64                  * In other words, the only way for checksums not to be used
  65                  * is if both hosts in their SYNs set A=0."
  66                  *
  67                  * Section 3.3.0:
  68                  * "If a checksum is not present when its use has been
  69                  * negotiated, the receiver MUST close the subflow with a RST as
  70                  * it is considered broken."
  71                  *
  72                  * We don't implement DSS checksum - fall back to TCP.
  73                  */
  74                 if (flags & MPTCP_CAP_CHECKSUM_REQD)
  75                         break;
  76
  77                 mp_opt->mp_capable = 1;
  78                 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
  79                         mp_opt->sndr_key = get_unaligned_be64(ptr);
  80                         ptr += 8;
  81                 }
  82                 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
  83                         mp_opt->rcvr_key = get_unaligned_be64(ptr);
  84                         ptr += 8;
  85                 }
  86                 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA) {
  87                         /* Section 3.1.:
  88                          * "the data parameters in a MP_CAPABLE are semantically
  89                          * equivalent to those in a DSS option and can be used
  90                          * interchangeably."
  91                          */
  92                         mp_opt->dss = 1;
  93                         mp_opt->use_map = 1;
  94                         mp_opt->mpc_map = 1;
  95                         mp_opt->data_len = get_unaligned_be16(ptr);
  96                         ptr += 2;
  97                 }
  98                 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d",
  99                          version, flags, opsize, mp_opt->sndr_key,
 100                          mp_opt->rcvr_key, mp_opt->data_len);
 101                 break;
 102
 103         case MPTCPOPT_MP_JOIN:
 104                 mp_opt->mp_join = 1;
 105                 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
 106                         mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
 107                         mp_opt->join_id = *ptr++;
 108                         mp_opt->token = get_unaligned_be32(ptr);
 109                         ptr += 4;
 110                         mp_opt->nonce = get_unaligned_be32(ptr);
 111                         ptr += 4;
 112                         pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
 113                                  mp_opt->backup, mp_opt->join_id,
 114                                  mp_opt->token, mp_opt->nonce);
 115                 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) {
 116                         mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
 117                         mp_opt->join_id = *ptr++;
 118                         mp_opt->thmac = get_unaligned_be64(ptr);
 119                         ptr += 8;
 120                         mp_opt->nonce = get_unaligned_be32(ptr);
 121                         ptr += 4;
 122                         pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
 123                                  mp_opt->backup, mp_opt->join_id,
 124                                  mp_opt->thmac, mp_opt->nonce);
 125                 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
 126                         ptr += 2;
 127                         memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
 128                         pr_debug("MP_JOIN hmac");
 129                 } else {
 130                         pr_warn("MP_JOIN bad option size");
 131                         mp_opt->mp_join = 0;
 132                 }
 133                 break;
 134
 135         case MPTCPOPT_DSS:
 136                 pr_debug("DSS");
 137                 ptr++;
 138
 139                 /* we must clear 'mpc_map' be able to detect MP_CAPABLE
 140                  * map vs DSS map in mptcp_incoming_options(), and reconstruct
 141                  * map info accordingly
 142                  */
 143                 mp_opt->mpc_map = 0;
 144                 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
 145                 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
 146                 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
 147                 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
 148                 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
 149                 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
 150
 151                 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
 152                          mp_opt->data_fin, mp_opt->dsn64,
 153                          mp_opt->use_map, mp_opt->ack64,
 154                          mp_opt->use_ack);
 155
 156                 expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
 157
 158                 if (mp_opt->use_ack) {
 159                         if (mp_opt->ack64)
 160                                 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
 161                         else
 162                                 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
 163                 }
 164
 165                 if (mp_opt->use_map) {
 166                         if (mp_opt->dsn64)
 167                                 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
 168                         else
 169                                 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
 170                 }
 171
 172                 /* RFC 6824, Section 3.3:
 173                  * If a checksum is present, but its use had
 174                  * not been negotiated in the MP_CAPABLE handshake,
 175                  * the checksum field MUST be ignored.
 176                  */
 177                 if (opsize != expected_opsize &&
 178                     opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
 179                         break;
 180
 181                 mp_opt->dss = 1;
 182
 183                 if (mp_opt->use_ack) {
 184                         if (mp_opt->ack64) {
 185                                 mp_opt->data_ack = get_unaligned_be64(ptr);
 186                                 ptr += 8;
 187                         } else {
 188                                 mp_opt->data_ack = get_unaligned_be32(ptr);
 189                                 ptr += 4;
 190                         }
 191
 192                         pr_debug("data_ack=%llu", mp_opt->data_ack);
 193                 }
 194
 195                 if (mp_opt->use_map) {
 196                         if (mp_opt->dsn64) {
 197                                 mp_opt->data_seq = get_unaligned_be64(ptr);
 198                                 ptr += 8;
 199                         } else {
 200                                 mp_opt->data_seq = get_unaligned_be32(ptr);
 201                                 ptr += 4;
 202                         }
 203
 204                         mp_opt->subflow_seq = get_unaligned_be32(ptr);
 205                         ptr += 4;
 206
 207                         mp_opt->data_len = get_unaligned_be16(ptr);
 208                         ptr += 2;
 209
 210                         pr_debug("data_seq=%llu subflow_seq=%u data_len=%u",
 211                                  mp_opt->data_seq, mp_opt->subflow_seq,
 212                                  mp_opt->data_len);
 213                 }
 214
 215                 break;
 216
 217         case MPTCPOPT_ADD_ADDR:
 218                 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
 219                 if (!mp_opt->echo) {
 220                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
 221                             opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
 222                                 mp_opt->family = MPTCP_ADDR_IPVERSION_4;
 223 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 224                         else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
 225                                  opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
 226                                 mp_opt->family = MPTCP_ADDR_IPVERSION_6;
 227 #endif
 228                         else
 229                                 break;
 230                 } else {
 231                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
 232                             opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
 233                                 mp_opt->family = MPTCP_ADDR_IPVERSION_4;
 234 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 235                         else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
 236                                  opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
 237                                 mp_opt->family = MPTCP_ADDR_IPVERSION_6;
 238 #endif
 239                         else
 240                                 break;
 241                 }
 242
 243                 mp_opt->add_addr = 1;
 244                 mp_opt->addr_id = *ptr++;
 245                 pr_debug("ADD_ADDR: id=%d, echo=%d", mp_opt->addr_id, mp_opt->echo);
 246                 if (mp_opt->family == MPTCP_ADDR_IPVERSION_4) {
 247                         memcpy((u8 *)&mp_opt->addr.s_addr, (u8 *)ptr, 4);
 248                         ptr += 4;
 249                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
 250                             opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
 251                                 mp_opt->port = get_unaligned_be16(ptr);
 252                                 ptr += 2;
 253                         }
 254                 }
 255 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 256                 else {
 257                         memcpy(mp_opt->addr6.s6_addr, (u8 *)ptr, 16);
 258                         ptr += 16;
 259                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
 260                             opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
 261                                 mp_opt->port = get_unaligned_be16(ptr);
 262                                 ptr += 2;
 263                         }
 264                 }
 265 #endif
 266                 if (!mp_opt->echo) {
 267                         mp_opt->ahmac = get_unaligned_be64(ptr);
 268                         ptr += 8;
 269                 }
 270                 break;
 271
 272         case MPTCPOPT_RM_ADDR:
 273                 if (opsize != TCPOLEN_MPTCP_RM_ADDR_BASE)
 274                         break;
 275
 276                 ptr++;
 277
 278                 mp_opt->rm_addr = 1;
 279                 mp_opt->rm_id = *ptr++;
 280                 pr_debug("RM_ADDR: id=%d", mp_opt->rm_id);
 281                 break;
 282
 283         default:
 284                 break;
 285         }
 286 }
 287
 288 void mptcp_get_options(const struct sk_buff *skb,
 289                        struct mptcp_options_received *mp_opt)
 290 {
 291         const struct tcphdr *th = tcp_hdr(skb);
 292         const unsigned char *ptr;
 293         int length;
 294
 295         /* initialize option status */
 296         mp_opt->mp_capable = 0;
 297         mp_opt->mp_join = 0;
 298         mp_opt->add_addr = 0;
 299         mp_opt->ahmac = 0;
 300         mp_opt->port = 0;
 301         mp_opt->rm_addr = 0;
 302         mp_opt->dss = 0;
 303
 304         length = (th->doff * 4) - sizeof(struct tcphdr);
 305         ptr = (const unsigned char *)(th + 1);
 306
 307         while (length > 0) {
 308                 int opcode = *ptr++;
 309                 int opsize;
 310
 311                 switch (opcode) {
 312                 case TCPOPT_EOL:
 313                         return;
 314                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 315                         length--;
 316                         continue;
 317                 default:
 318                         opsize = *ptr++;
 319                         if (opsize < 2) /* "silly options" */
 320                                 return;
 321                         if (opsize > length)
 322                                 return; /* don't parse partial options */
 323                         if (opcode == TCPOPT_MPTCP)
 324                                 mptcp_parse_option(skb, ptr, opsize, mp_opt);
 325                         ptr += opsize - 2;
 326                         length -= opsize;
 327                 }
 328         }
 329 }
 330
 331 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 332                        unsigned int *size, struct mptcp_out_options *opts)
 333 {
 334         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 335
 336         /* we will use snd_isn to detect first pkt [re]transmission
 337          * in mptcp_established_options_mp()
 338          */
 339         subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
 340         if (subflow->request_mptcp) {
 341                 opts->suboptions = OPTION_MPTCP_MPC_SYN;
 342                 *size = TCPOLEN_MPTCP_MPC_SYN;
 343                 return true;
 344         } else if (subflow->request_join) {
 345                 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
 346                          subflow->local_nonce);
 347                 opts->suboptions = OPTION_MPTCP_MPJ_SYN;
 348                 opts->join_id = subflow->local_id;
 349                 opts->token = subflow->remote_token;
 350                 opts->nonce = subflow->local_nonce;
 351                 opts->backup = subflow->request_bkup;
 352                 *size = TCPOLEN_MPTCP_MPJ_SYN;
 353                 return true;
 354         }
 355         return false;
 356 }
 357
 358 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
 359  * TCP can't schedule delack timer before the subflow is fully established.
 360  * MPTCP uses the delack timer to do 3rd ack retransmissions
 361  */
 362 static void schedule_3rdack_retransmission(struct sock *sk)
 363 {
 364         struct inet_connection_sock *icsk = inet_csk(sk);
 365         struct tcp_sock *tp = tcp_sk(sk);
 366         unsigned long timeout;
 367
 368         /* reschedule with a timeout above RTT, as we must look only for drop */
 369         if (tp->srtt_us)
 370                 timeout = tp->srtt_us << 1;
 371         else
 372                 timeout = TCP_TIMEOUT_INIT;
 373
 374         WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
 375         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 376         icsk->icsk_ack.timeout = timeout;
 377         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 378 }
 379
 380 static void clear_3rdack_retransmission(struct sock *sk)
 381 {
 382         struct inet_connection_sock *icsk = inet_csk(sk);
 383
 384         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 385         icsk->icsk_ack.timeout = 0;
 386         icsk->icsk_ack.ato = 0;
 387         icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
 388 }
 389
 390 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 391                                          unsigned int *size,
 392                                          unsigned int remaining,
 393                                          struct mptcp_out_options *opts)
 394 {
 395         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 396         struct mptcp_ext *mpext;
 397         unsigned int data_len;
 398
 399         /* When skb is not available, we better over-estimate the emitted
 400          * options len. A full DSS option (28 bytes) is longer than
 401          * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
 402          * tell the caller to defer the estimate to
 403          * mptcp_established_options_dss(), which will reserve enough space.
 404          */
 405         if (!skb)
 406                 return false;
 407
 408         /* MPC/MPJ needed only on 3rd ack packet */
 409         if (subflow->fully_established ||
 410             subflow->snd_isn != TCP_SKB_CB(skb)->seq)
 411                 return false;
 412
 413         if (subflow->mp_capable) {
 414                 mpext = mptcp_get_ext(skb);
 415                 data_len = mpext ? mpext->data_len : 0;
 416
 417                 /* we will check ext_copy.data_len in mptcp_write_options() to
 418                  * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
 419                  * TCPOLEN_MPTCP_MPC_ACK
 420                  */
 421                 opts->ext_copy.data_len = data_len;
 422                 opts->suboptions = OPTION_MPTCP_MPC_ACK;
 423                 opts->sndr_key = subflow->local_key;
 424                 opts->rcvr_key = subflow->remote_key;
 425
 426                 /* Section 3.1.
 427                  * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
 428                  * packets that start the first subflow of an MPTCP connection,
 429                  * as well as the first packet that carries data
 430                  */
 431                 if (data_len > 0)
 432                         *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
 433                 else
 434                         *size = TCPOLEN_MPTCP_MPC_ACK;
 435
 436                 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
 437                          subflow, subflow->local_key, subflow->remote_key,
 438                          data_len);
 439
 440                 return true;
 441         } else if (subflow->mp_join) {
 442                 opts->suboptions = OPTION_MPTCP_MPJ_ACK;
 443                 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
 444                 *size = TCPOLEN_MPTCP_MPJ_ACK;
 445                 pr_debug("subflow=%p", subflow);
 446
 447                 schedule_3rdack_retransmission(sk);
 448                 return true;
 449         }
 450         return false;
 451 }
 452
 453 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
 454                                  struct sk_buff *skb, struct mptcp_ext *ext)
 455 {
 456         /* The write_seq value has already been incremented, so the actual
 457          * sequence number for the DATA_FIN is one less.
 458          */
 459         u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
 460
 461         if (!ext->use_map || !skb->len) {
 462                 /* RFC6824 requires a DSS mapping with specific values
 463                  * if DATA_FIN is set but no data payload is mapped
 464                  */
 465                 ext->data_fin = 1;
 466                 ext->use_map = 1;
 467                 ext->dsn64 = 1;
 468                 ext->data_seq = data_fin_tx_seq;
 469                 ext->subflow_seq = 0;
 470                 ext->data_len = 1;
 471         } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
 472                 /* If there's an existing DSS mapping and it is the
 473                  * final mapping, DATA_FIN consumes 1 additional byte of
 474                  * mapping space.
 475                  */
 476                 ext->data_fin = 1;
 477                 ext->data_len++;
 478         }
 479 }
 480
 481 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 482                                           unsigned int *size,
 483                                           unsigned int remaining,
 484                                           struct mptcp_out_options *opts)
 485 {
 486         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 487         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 488         unsigned int dss_size = 0;
 489         u64 snd_data_fin_enable;
 490         struct mptcp_ext *mpext;
 491         unsigned int ack_size;
 492         bool ret = false;
 493
 494         mpext = skb ? mptcp_get_ext(skb) : NULL;
 495         snd_data_fin_enable = READ_ONCE(msk->snd_data_fin_enable);
 496
 497         if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
 498                 unsigned int map_size;
 499
 500                 map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
 501
 502                 remaining -= map_size;
 503                 dss_size = map_size;
 504                 if (mpext)
 505                         opts->ext_copy = *mpext;
 506
 507                 if (skb && snd_data_fin_enable)
 508                         mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
 509                 ret = true;
 510         }
 511
 512         /* passive sockets msk will set the 'can_ack' after accept(), even
 513          * if the first subflow may have the already the remote key handy
 514          */
 515         opts->ext_copy.use_ack = 0;
 516         if (!READ_ONCE(msk->can_ack)) {
 517                 *size = ALIGN(dss_size, 4);
 518                 return ret;
 519         }
 520
 521         if (READ_ONCE(msk->use_64bit_ack)) {
 522                 ack_size = TCPOLEN_MPTCP_DSS_ACK64;
 523                 opts->ext_copy.data_ack = READ_ONCE(msk->ack_seq);
 524                 opts->ext_copy.ack64 = 1;
 525         } else {
 526                 ack_size = TCPOLEN_MPTCP_DSS_ACK32;
 527                 opts->ext_copy.data_ack32 = (uint32_t)READ_ONCE(msk->ack_seq);
 528                 opts->ext_copy.ack64 = 0;
 529         }
 530         opts->ext_copy.use_ack = 1;
 531
 532         /* Add kind/length/subtype/flag overhead if mapping is not populated */
 533         if (dss_size == 0)
 534                 ack_size += TCPOLEN_MPTCP_DSS_BASE;
 535
 536         dss_size += ack_size;
 537
 538         *size = ALIGN(dss_size, 4);
 539         return true;
 540 }
 541
 542 static u64 add_addr_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 543                                   struct in_addr *addr)
 544 {
 545         u8 hmac[SHA256_DIGEST_SIZE];
 546         u8 msg[7];
 547
 548         msg[0] = addr_id;
 549         memcpy(&msg[1], &addr->s_addr, 4);
 550         msg[5] = 0;
 551         msg[6] = 0;
 552
 553         mptcp_crypto_hmac_sha(key1, key2, msg, 7, hmac);
 554
 555         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 556 }
 557
 558 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 559 static u64 add_addr6_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 560                                    struct in6_addr *addr)
 561 {
 562         u8 hmac[SHA256_DIGEST_SIZE];
 563         u8 msg[19];
 564
 565         msg[0] = addr_id;
 566         memcpy(&msg[1], &addr->s6_addr, 16);
 567         msg[17] = 0;
 568         msg[18] = 0;
 569
 570         mptcp_crypto_hmac_sha(key1, key2, msg, 19, hmac);
 571
 572         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 573 }
 574 #endif
 575
 576 static bool mptcp_established_options_add_addr(struct sock *sk,
 577                                                unsigned int *size,
 578                                                unsigned int remaining,
 579                                                struct mptcp_out_options *opts)
 580 {
 581         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 582         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 583         struct mptcp_addr_info saddr;
 584         bool echo;
 585         int len;
 586
 587         if (!mptcp_pm_should_add_signal(msk) ||
 588             !(mptcp_pm_add_addr_signal(msk, remaining, &saddr, &echo)))
 589                 return false;
 590
 591         len = mptcp_add_addr_len(saddr.family, echo);
 592         if (remaining < len)
 593                 return false;
 594
 595         *size = len;
 596         opts->addr_id = saddr.id;
 597         if (saddr.family == AF_INET) {
 598                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
 599                 opts->addr = saddr.addr;
 600                 if (!echo) {
 601                         opts->ahmac = add_addr_generate_hmac(msk->local_key,
 602                                                              msk->remote_key,
 603                                                              opts->addr_id,
 604                                                              &opts->addr);
 605                 }
 606         }
 607 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 608         else if (saddr.family == AF_INET6) {
 609                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR6;
 610                 opts->addr6 = saddr.addr6;
 611                 if (!echo) {
 612                         opts->ahmac = add_addr6_generate_hmac(msk->local_key,
 613                                                               msk->remote_key,
 614                                                               opts->addr_id,
 615                                                               &opts->addr6);
 616                 }
 617         }
 618 #endif
 619         pr_debug("addr_id=%d, ahmac=%llu, echo=%d", opts->addr_id, opts->ahmac, echo);
 620
 621         return true;
 622 }
 623
 624 static bool mptcp_established_options_rm_addr(struct sock *sk,
 625                                               unsigned int *size,
 626                                               unsigned int remaining,
 627                                               struct mptcp_out_options *opts)
 628 {
 629         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 630         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 631         u8 rm_id;
 632
 633         if (!mptcp_pm_should_rm_signal(msk) ||
 634             !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_id)))
 635                 return false;
 636
 637         if (remaining < TCPOLEN_MPTCP_RM_ADDR_BASE)
 638                 return false;
 639
 640         *size = TCPOLEN_MPTCP_RM_ADDR_BASE;
 641         opts->suboptions |= OPTION_MPTCP_RM_ADDR;
 642         opts->rm_id = rm_id;
 643
 644         pr_debug("rm_id=%d", opts->rm_id);
 645
 646         return true;
 647 }
 648
 649 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 650                                unsigned int *size, unsigned int remaining,
 651                                struct mptcp_out_options *opts)
 652 {
 653         unsigned int opt_size = 0;
 654         bool ret = false;
 655
 656         opts->suboptions = 0;
 657
 658         if (unlikely(mptcp_check_fallback(sk)))
 659                 return false;
 660
 661         /* prevent adding of any MPTCP related options on reset packet
 662          * until we support MP_TCPRST/MP_FASTCLOSE
 663          */
 664         if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
 665                 return false;
 666
 667         if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
 668                 ret = true;
 669         else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
 670                                                opts))
 671                 ret = true;
 672
 673         /* we reserved enough space for the above options, and exceeding the
 674          * TCP option space would be fatal
 675          */
 676         if (WARN_ON_ONCE(opt_size > remaining))
 677                 return false;
 678
 679         *size += opt_size;
 680         remaining -= opt_size;
 681         if (mptcp_established_options_add_addr(sk, &opt_size, remaining, opts)) {
 682                 *size += opt_size;
 683                 remaining -= opt_size;
 684                 ret = true;
 685         } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
 686                 *size += opt_size;
 687                 remaining -= opt_size;
 688                 ret = true;
 689         }
 690
 691         return ret;
 692 }
 693
 694 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 695                           struct mptcp_out_options *opts)
 696 {
 697         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 698
 699         if (subflow_req->mp_capable) {
 700                 opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
 701                 opts->sndr_key = subflow_req->local_key;
 702                 *size = TCPOLEN_MPTCP_MPC_SYNACK;
 703                 pr_debug("subflow_req=%p, local_key=%llu",
 704                          subflow_req, subflow_req->local_key);
 705                 return true;
 706         } else if (subflow_req->mp_join) {
 707                 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
 708                 opts->backup = subflow_req->backup;
 709                 opts->join_id = subflow_req->local_id;
 710                 opts->thmac = subflow_req->thmac;
 711                 opts->nonce = subflow_req->local_nonce;
 712                 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
 713                          subflow_req, opts->backup, opts->join_id,
 714                          opts->thmac, opts->nonce);
 715                 *size = TCPOLEN_MPTCP_MPJ_SYNACK;
 716                 return true;
 717         }
 718         return false;
 719 }
 720
 721 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
 722                                     struct mptcp_subflow_context *subflow,
 723                                     struct sk_buff *skb,
 724                                     struct mptcp_options_received *mp_opt)
 725 {
 726         /* here we can process OoO, in-window pkts, only in-sequence 4th ack
 727          * will make the subflow fully established
 728          */
 729         if (likely(subflow->fully_established)) {
 730                 /* on passive sockets, check for 3rd ack retransmission
 731                  * note that msk is always set by subflow_syn_recv_sock()
 732                  * for mp_join subflows
 733                  */
 734                 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
 735                     TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
 736                     subflow->mp_join && mp_opt->mp_join &&
 737                     READ_ONCE(msk->pm.server_side))
 738                         tcp_send_ack(ssk);
 739                 goto fully_established;
 740         }
 741
 742         /* we must process OoO packets before the first subflow is fully
 743          * established. OoO packets are instead a protocol violation
 744          * for MP_JOIN subflows as the peer must not send any data
 745          * before receiving the forth ack - cfr. RFC 8684 section 3.2.
 746          */
 747         if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
 748                 if (subflow->mp_join)
 749                         goto reset;
 750                 return subflow->mp_capable;
 751         }
 752
 753         if (mp_opt->dss && mp_opt->use_ack) {
 754                 /* subflows are fully established as soon as we get any
 755                  * additional ack.
 756                  */
 757                 subflow->fully_established = 1;
 758                 WRITE_ONCE(msk->fully_established, true);
 759                 goto fully_established;
 760         }
 761
 762         /* If the first established packet does not contain MP_CAPABLE + data
 763          * then fallback to TCP. Fallback scenarios requires a reset for
 764          * MP_JOIN subflows.
 765          */
 766         if (!mp_opt->mp_capable) {
 767                 if (subflow->mp_join)
 768                         goto reset;
 769                 subflow->mp_capable = 0;
 770                 pr_fallback(msk);
 771                 __mptcp_do_fallback(msk);
 772                 return false;
 773         }
 774
 775         if (unlikely(!READ_ONCE(msk->pm.server_side)))
 776                 pr_warn_once("bogus mpc option on established client sk");
 777         mptcp_subflow_fully_established(subflow, mp_opt);
 778
 779 fully_established:
 780         if (likely(subflow->pm_notified))
 781                 return true;
 782
 783         subflow->pm_notified = 1;
 784         if (subflow->mp_join) {
 785                 clear_3rdack_retransmission(ssk);
 786                 mptcp_pm_subflow_established(msk, subflow);
 787         } else {
 788                 mptcp_pm_fully_established(msk);
 789         }
 790         return true;
 791
 792 reset:
 793         mptcp_subflow_reset(ssk);
 794         return false;
 795 }
 796
 797 static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
 798 {
 799         u32 old_ack32, cur_ack32;
 800
 801         if (use_64bit)
 802                 return cur_ack;
 803
 804         old_ack32 = (u32)old_ack;
 805         cur_ack32 = (u32)cur_ack;
 806         cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
 807         if (unlikely(before(cur_ack32, old_ack32)))
 808                 return cur_ack + (1LL << 32);
 809         return cur_ack;
 810 }
 811
 812 static void update_una(struct mptcp_sock *msk,
 813                        struct mptcp_options_received *mp_opt)
 814 {
 815         u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
 816         u64 write_seq = READ_ONCE(msk->write_seq);
 817
 818         /* avoid ack expansion on update conflict, to reduce the risk of
 819          * wrongly expanding to a future ack sequence number, which is way
 820          * more dangerous than missing an ack
 821          */
 822         new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
 823
 824         /* ACK for data not even sent yet? Ignore. */
 825         if (after64(new_snd_una, write_seq))
 826                 new_snd_una = old_snd_una;
 827
 828         while (after64(new_snd_una, old_snd_una)) {
 829                 snd_una = old_snd_una;
 830                 old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
 831                                                new_snd_una);
 832                 if (old_snd_una == snd_una) {
 833                         mptcp_data_acked((struct sock *)msk);
 834                         break;
 835                 }
 836         }
 837 }
 838
 839 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
 840 {
 841         /* Skip if DATA_FIN was already received.
 842          * If updating simultaneously with the recvmsg loop, values
 843          * should match. If they mismatch, the peer is misbehaving and
 844          * we will prefer the most recent information.
 845          */
 846         if (READ_ONCE(msk->rcv_data_fin) || !READ_ONCE(msk->first))
 847                 return false;
 848
 849         WRITE_ONCE(msk->rcv_data_fin_seq,
 850                    expand_ack(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
 851         WRITE_ONCE(msk->rcv_data_fin, 1);
 852
 853         return true;
 854 }
 855
 856 static bool add_addr_hmac_valid(struct mptcp_sock *msk,
 857                                 struct mptcp_options_received *mp_opt)
 858 {
 859         u64 hmac = 0;
 860
 861         if (mp_opt->echo)
 862                 return true;
 863
 864         if (mp_opt->family == MPTCP_ADDR_IPVERSION_4)
 865                 hmac = add_addr_generate_hmac(msk->remote_key,
 866                                               msk->local_key,
 867                                               mp_opt->addr_id, &mp_opt->addr);
 868 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 869         else
 870                 hmac = add_addr6_generate_hmac(msk->remote_key,
 871                                                msk->local_key,
 872                                                mp_opt->addr_id, &mp_opt->addr6);
 873 #endif
 874
 875         pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
 876                  msk, (unsigned long long)hmac,
 877                  (unsigned long long)mp_opt->ahmac);
 878
 879         return hmac == mp_opt->ahmac;
 880 }
 881
 882 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 883 {
 884         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 885         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 886         struct mptcp_options_received mp_opt;
 887         struct mptcp_ext *mpext;
 888
 889         if (__mptcp_check_fallback(msk))
 890                 return;
 891
 892         mptcp_get_options(skb, &mp_opt);
 893         if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
 894                 return;
 895
 896         if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
 897                 struct mptcp_addr_info addr;
 898
 899                 addr.port = htons(mp_opt.port);
 900                 addr.id = mp_opt.addr_id;
 901                 if (mp_opt.family == MPTCP_ADDR_IPVERSION_4) {
 902                         addr.family = AF_INET;
 903                         addr.addr = mp_opt.addr;
 904                 }
 905 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 906                 else if (mp_opt.family == MPTCP_ADDR_IPVERSION_6) {
 907                         addr.family = AF_INET6;
 908                         addr.addr6 = mp_opt.addr6;
 909                 }
 910 #endif
 911                 if (!mp_opt.echo) {
 912                         mptcp_pm_add_addr_received(msk, &addr);
 913                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
 914                 } else {
 915                         mptcp_pm_del_add_timer(msk, &addr);
 916                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
 917                 }
 918                 mp_opt.add_addr = 0;
 919         }
 920
 921         if (mp_opt.rm_addr) {
 922                 mptcp_pm_rm_addr_received(msk, mp_opt.rm_id);
 923                 mp_opt.rm_addr = 0;
 924         }
 925
 926         if (!mp_opt.dss)
 927                 return;
 928
 929         /* we can't wait for recvmsg() to update the ack_seq, otherwise
 930          * monodirectional flows will stuck
 931          */
 932         if (mp_opt.use_ack)
 933                 update_una(msk, &mp_opt);
 934
 935         /* Zero-data-length packets are dropped by the caller and not
 936          * propagated to the MPTCP layer, so the skb extension does not
 937          * need to be allocated or populated. DATA_FIN information, if
 938          * present, needs to be updated here before the skb is freed.
 939          */
 940         if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
 941                 if (mp_opt.data_fin && mp_opt.data_len == 1 &&
 942                     mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
 943                     schedule_work(&msk->work))
 944                         sock_hold(subflow->conn);
 945
 946                 return;
 947         }
 948
 949         mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
 950         if (!mpext)
 951                 return;
 952
 953         memset(mpext, 0, sizeof(*mpext));
 954
 955         if (mp_opt.use_map) {
 956                 if (mp_opt.mpc_map) {
 957                         /* this is an MP_CAPABLE carrying MPTCP data
 958                          * we know this map the first chunk of data
 959                          */
 960                         mptcp_crypto_key_sha(subflow->remote_key, NULL,
 961                                              &mpext->data_seq);
 962                         mpext->data_seq++;
 963                         mpext->subflow_seq = 1;
 964                         mpext->dsn64 = 1;
 965                         mpext->mpc_map = 1;
 966                         mpext->data_fin = 0;
 967                 } else {
 968                         mpext->data_seq = mp_opt.data_seq;
 969                         mpext->subflow_seq = mp_opt.subflow_seq;
 970                         mpext->dsn64 = mp_opt.dsn64;
 971                         mpext->data_fin = mp_opt.data_fin;
 972                 }
 973                 mpext->data_len = mp_opt.data_len;
 974                 mpext->use_map = 1;
 975         }
 976 }
 977
 978 void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
 979 {
 980         if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
 981              OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
 982                 u8 len;
 983
 984                 if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
 985                         len = TCPOLEN_MPTCP_MPC_SYN;
 986                 else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
 987                         len = TCPOLEN_MPTCP_MPC_SYNACK;
 988                 else if (opts->ext_copy.data_len)
 989                         len = TCPOLEN_MPTCP_MPC_ACK_DATA;
 990                 else
 991                         len = TCPOLEN_MPTCP_MPC_ACK;
 992
 993                 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
 994                                       MPTCP_SUPPORTED_VERSION,
 995                                       MPTCP_CAP_HMAC_SHA256);
 996
 997                 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
 998                     opts->suboptions))
 999                         goto mp_capable_done;
1000
1001                 put_unaligned_be64(opts->sndr_key, ptr);
1002                 ptr += 2;
1003                 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1004                         goto mp_capable_done;
1005
1006                 put_unaligned_be64(opts->rcvr_key, ptr);
1007                 ptr += 2;
1008                 if (!opts->ext_copy.data_len)
1009                         goto mp_capable_done;
1010
1011                 put_unaligned_be32(opts->ext_copy.data_len << 16 |
1012                                    TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1013                 ptr += 1;
1014         }
1015
1016 mp_capable_done:
1017         if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
1018                 if (opts->ahmac)
1019                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1020                                               TCPOLEN_MPTCP_ADD_ADDR, 0,
1021                                               opts->addr_id);
1022                 else
1023                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1024                                               TCPOLEN_MPTCP_ADD_ADDR_BASE,
1025                                               MPTCP_ADDR_ECHO,
1026                                               opts->addr_id);
1027                 memcpy((u8 *)ptr, (u8 *)&opts->addr.s_addr, 4);
1028                 ptr += 1;
1029                 if (opts->ahmac) {
1030                         put_unaligned_be64(opts->ahmac, ptr);
1031                         ptr += 2;
1032                 }
1033         }
1034
1035 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1036         if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions) {
1037                 if (opts->ahmac)
1038                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1039                                               TCPOLEN_MPTCP_ADD_ADDR6, 0,
1040                                               opts->addr_id);
1041                 else
1042                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1043                                               TCPOLEN_MPTCP_ADD_ADDR6_BASE,
1044                                               MPTCP_ADDR_ECHO,
1045                                               opts->addr_id);
1046                 memcpy((u8 *)ptr, opts->addr6.s6_addr, 16);
1047                 ptr += 4;
1048                 if (opts->ahmac) {
1049                         put_unaligned_be64(opts->ahmac, ptr);
1050                         ptr += 2;
1051                 }
1052         }
1053 #endif
1054
1055         if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1056                 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1057                                       TCPOLEN_MPTCP_RM_ADDR_BASE,
1058                                       0, opts->rm_id);
1059         }
1060
1061         if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1062                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1063                                       TCPOLEN_MPTCP_MPJ_SYN,
1064                                       opts->backup, opts->join_id);
1065                 put_unaligned_be32(opts->token, ptr);
1066                 ptr += 1;
1067                 put_unaligned_be32(opts->nonce, ptr);
1068                 ptr += 1;
1069         }
1070
1071         if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1072                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1073                                       TCPOLEN_MPTCP_MPJ_SYNACK,
1074                                       opts->backup, opts->join_id);
1075                 put_unaligned_be64(opts->thmac, ptr);
1076                 ptr += 2;
1077                 put_unaligned_be32(opts->nonce, ptr);
1078                 ptr += 1;
1079         }
1080
1081         if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1082                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1083                                       TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1084                 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1085                 ptr += 5;
1086         }
1087
1088         if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
1089                 struct mptcp_ext *mpext = &opts->ext_copy;
1090                 u8 len = TCPOLEN_MPTCP_DSS_BASE;
1091                 u8 flags = 0;
1092
1093                 if (mpext->use_ack) {
1094                         flags = MPTCP_DSS_HAS_ACK;
1095                         if (mpext->ack64) {
1096                                 len += TCPOLEN_MPTCP_DSS_ACK64;
1097                                 flags |= MPTCP_DSS_ACK64;
1098                         } else {
1099                                 len += TCPOLEN_MPTCP_DSS_ACK32;
1100                         }
1101                 }
1102
1103                 if (mpext->use_map) {
1104                         len += TCPOLEN_MPTCP_DSS_MAP64;
1105
1106                         /* Use only 64-bit mapping flags for now, add
1107                          * support for optional 32-bit mappings later.
1108                          */
1109                         flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1110                         if (mpext->data_fin)
1111                                 flags |= MPTCP_DSS_DATA_FIN;
1112                 }
1113
1114                 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
1115
1116                 if (mpext->use_ack) {
1117                         if (mpext->ack64) {
1118                                 put_unaligned_be64(mpext->data_ack, ptr);
1119                                 ptr += 2;
1120                         } else {
1121                                 put_unaligned_be32(mpext->data_ack32, ptr);
1122                                 ptr += 1;
1123                         }
1124                 }
1125
1126                 if (mpext->use_map) {
1127                         put_unaligned_be64(mpext->data_seq, ptr);
1128                         ptr += 2;
1129                         put_unaligned_be32(mpext->subflow_seq, ptr);
1130                         ptr += 1;
1131                         put_unaligned_be32(mpext->data_len << 16 |
1132                                            TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1133                 }
1134         }
1135 }