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                         mp_opt->mp_join = 0;
 131                 }
 132                 break;
 133
 134         case MPTCPOPT_DSS:
 135                 pr_debug("DSS");
 136                 ptr++;
 137
 138                 /* we must clear 'mpc_map' be able to detect MP_CAPABLE
 139                  * map vs DSS map in mptcp_incoming_options(), and reconstruct
 140                  * map info accordingly
 141                  */
 142                 mp_opt->mpc_map = 0;
 143                 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
 144                 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
 145                 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
 146                 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
 147                 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
 148                 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
 149
 150                 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
 151                          mp_opt->data_fin, mp_opt->dsn64,
 152                          mp_opt->use_map, mp_opt->ack64,
 153                          mp_opt->use_ack);
 154
 155                 expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
 156
 157                 if (mp_opt->use_ack) {
 158                         if (mp_opt->ack64)
 159                                 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
 160                         else
 161                                 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
 162                 }
 163
 164                 if (mp_opt->use_map) {
 165                         if (mp_opt->dsn64)
 166                                 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
 167                         else
 168                                 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
 169                 }
 170
 171                 /* RFC 6824, Section 3.3:
 172                  * If a checksum is present, but its use had
 173                  * not been negotiated in the MP_CAPABLE handshake,
 174                  * the checksum field MUST be ignored.
 175                  */
 176                 if (opsize != expected_opsize &&
 177                     opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
 178                         break;
 179
 180                 mp_opt->dss = 1;
 181
 182                 if (mp_opt->use_ack) {
 183                         if (mp_opt->ack64) {
 184                                 mp_opt->data_ack = get_unaligned_be64(ptr);
 185                                 ptr += 8;
 186                         } else {
 187                                 mp_opt->data_ack = get_unaligned_be32(ptr);
 188                                 ptr += 4;
 189                         }
 190
 191                         pr_debug("data_ack=%llu", mp_opt->data_ack);
 192                 }
 193
 194                 if (mp_opt->use_map) {
 195                         if (mp_opt->dsn64) {
 196                                 mp_opt->data_seq = get_unaligned_be64(ptr);
 197                                 ptr += 8;
 198                         } else {
 199                                 mp_opt->data_seq = get_unaligned_be32(ptr);
 200                                 ptr += 4;
 201                         }
 202
 203                         mp_opt->subflow_seq = get_unaligned_be32(ptr);
 204                         ptr += 4;
 205
 206                         mp_opt->data_len = get_unaligned_be16(ptr);
 207                         ptr += 2;
 208
 209                         pr_debug("data_seq=%llu subflow_seq=%u data_len=%u",
 210                                  mp_opt->data_seq, mp_opt->subflow_seq,
 211                                  mp_opt->data_len);
 212                 }
 213
 214                 break;
 215
 216         case MPTCPOPT_ADD_ADDR:
 217                 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
 218                 if (!mp_opt->echo) {
 219                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
 220                             opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
 221                                 mp_opt->family = MPTCP_ADDR_IPVERSION_4;
 222 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 223                         else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
 224                                  opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
 225                                 mp_opt->family = MPTCP_ADDR_IPVERSION_6;
 226 #endif
 227                         else
 228                                 break;
 229                 } else {
 230                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
 231                             opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
 232                                 mp_opt->family = MPTCP_ADDR_IPVERSION_4;
 233 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 234                         else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
 235                                  opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
 236                                 mp_opt->family = MPTCP_ADDR_IPVERSION_6;
 237 #endif
 238                         else
 239                                 break;
 240                 }
 241
 242                 mp_opt->add_addr = 1;
 243                 mp_opt->addr_id = *ptr++;
 244                 pr_debug("ADD_ADDR: id=%d, echo=%d", mp_opt->addr_id, mp_opt->echo);
 245                 if (mp_opt->family == MPTCP_ADDR_IPVERSION_4) {
 246                         memcpy((u8 *)&mp_opt->addr.s_addr, (u8 *)ptr, 4);
 247                         ptr += 4;
 248                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
 249                             opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
 250                                 mp_opt->port = get_unaligned_be16(ptr);
 251                                 ptr += 2;
 252                         }
 253                 }
 254 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 255                 else {
 256                         memcpy(mp_opt->addr6.s6_addr, (u8 *)ptr, 16);
 257                         ptr += 16;
 258                         if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
 259                             opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
 260                                 mp_opt->port = get_unaligned_be16(ptr);
 261                                 ptr += 2;
 262                         }
 263                 }
 264 #endif
 265                 if (!mp_opt->echo) {
 266                         mp_opt->ahmac = get_unaligned_be64(ptr);
 267                         ptr += 8;
 268                 }
 269                 break;
 270
 271         case MPTCPOPT_RM_ADDR:
 272                 if (opsize != TCPOLEN_MPTCP_RM_ADDR_BASE)
 273                         break;
 274
 275                 ptr++;
 276
 277                 mp_opt->rm_addr = 1;
 278                 mp_opt->rm_id = *ptr++;
 279                 pr_debug("RM_ADDR: id=%d", mp_opt->rm_id);
 280                 break;
 281
 282         default:
 283                 break;
 284         }
 285 }
 286
 287 void mptcp_get_options(const struct sk_buff *skb,
 288                        struct mptcp_options_received *mp_opt)
 289 {
 290         const struct tcphdr *th = tcp_hdr(skb);
 291         const unsigned char *ptr;
 292         int length;
 293
 294         /* initialize option status */
 295         mp_opt->mp_capable = 0;
 296         mp_opt->mp_join = 0;
 297         mp_opt->add_addr = 0;
 298         mp_opt->ahmac = 0;
 299         mp_opt->port = 0;
 300         mp_opt->rm_addr = 0;
 301         mp_opt->dss = 0;
 302
 303         length = (th->doff * 4) - sizeof(struct tcphdr);
 304         ptr = (const unsigned char *)(th + 1);
 305
 306         while (length > 0) {
 307                 int opcode = *ptr++;
 308                 int opsize;
 309
 310                 switch (opcode) {
 311                 case TCPOPT_EOL:
 312                         return;
 313                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 314                         length--;
 315                         continue;
 316                 default:
 317                         if (length < 2)
 318                                 return;
 319                         opsize = *ptr++;
 320                         if (opsize < 2) /* "silly options" */
 321                                 return;
 322                         if (opsize > length)
 323                                 return; /* don't parse partial options */
 324                         if (opcode == TCPOPT_MPTCP)
 325                                 mptcp_parse_option(skb, ptr, opsize, mp_opt);
 326                         ptr += opsize - 2;
 327                         length -= opsize;
 328                 }
 329         }
 330 }
 331
 332 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 333                        unsigned int *size, struct mptcp_out_options *opts)
 334 {
 335         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 336
 337         /* we will use snd_isn to detect first pkt [re]transmission
 338          * in mptcp_established_options_mp()
 339          */
 340         subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
 341         if (subflow->request_mptcp) {
 342                 opts->suboptions = OPTION_MPTCP_MPC_SYN;
 343                 *size = TCPOLEN_MPTCP_MPC_SYN;
 344                 return true;
 345         } else if (subflow->request_join) {
 346                 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
 347                          subflow->local_nonce);
 348                 opts->suboptions = OPTION_MPTCP_MPJ_SYN;
 349                 opts->join_id = subflow->local_id;
 350                 opts->token = subflow->remote_token;
 351                 opts->nonce = subflow->local_nonce;
 352                 opts->backup = subflow->request_bkup;
 353                 *size = TCPOLEN_MPTCP_MPJ_SYN;
 354                 return true;
 355         }
 356         return false;
 357 }
 358
 359 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
 360  * TCP can't schedule delack timer before the subflow is fully established.
 361  * MPTCP uses the delack timer to do 3rd ack retransmissions
 362  */
 363 static void schedule_3rdack_retransmission(struct sock *sk)
 364 {
 365         struct inet_connection_sock *icsk = inet_csk(sk);
 366         struct tcp_sock *tp = tcp_sk(sk);
 367         unsigned long timeout;
 368
 369         /* reschedule with a timeout above RTT, as we must look only for drop */
 370         if (tp->srtt_us)
 371                 timeout = usecs_to_jiffies(tp->srtt_us >> (3 - 1));
 372         else
 373                 timeout = TCP_TIMEOUT_INIT;
 374         timeout += jiffies;
 375
 376         WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
 377         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 378         icsk->icsk_ack.timeout = timeout;
 379         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 380 }
 381
 382 static void clear_3rdack_retransmission(struct sock *sk)
 383 {
 384         struct inet_connection_sock *icsk = inet_csk(sk);
 385
 386         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 387         icsk->icsk_ack.timeout = 0;
 388         icsk->icsk_ack.ato = 0;
 389         icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
 390 }
 391
 392 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 393                                          unsigned int *size,
 394                                          unsigned int remaining,
 395                                          struct mptcp_out_options *opts)
 396 {
 397         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 398         struct mptcp_ext *mpext;
 399         unsigned int data_len;
 400
 401         /* When skb is not available, we better over-estimate the emitted
 402          * options len. A full DSS option (28 bytes) is longer than
 403          * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
 404          * tell the caller to defer the estimate to
 405          * mptcp_established_options_dss(), which will reserve enough space.
 406          */
 407         if (!skb)
 408                 return false;
 409
 410         /* MPC/MPJ needed only on 3rd ack packet */
 411         if (subflow->fully_established ||
 412             subflow->snd_isn != TCP_SKB_CB(skb)->seq)
 413                 return false;
 414
 415         if (subflow->mp_capable) {
 416                 mpext = mptcp_get_ext(skb);
 417                 data_len = mpext ? mpext->data_len : 0;
 418
 419                 /* we will check ext_copy.data_len in mptcp_write_options() to
 420                  * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
 421                  * TCPOLEN_MPTCP_MPC_ACK
 422                  */
 423                 opts->ext_copy.data_len = data_len;
 424                 opts->suboptions = OPTION_MPTCP_MPC_ACK;
 425                 opts->sndr_key = subflow->local_key;
 426                 opts->rcvr_key = subflow->remote_key;
 427
 428                 /* Section 3.1.
 429                  * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
 430                  * packets that start the first subflow of an MPTCP connection,
 431                  * as well as the first packet that carries data
 432                  */
 433                 if (data_len > 0)
 434                         *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
 435                 else
 436                         *size = TCPOLEN_MPTCP_MPC_ACK;
 437
 438                 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
 439                          subflow, subflow->local_key, subflow->remote_key,
 440                          data_len);
 441
 442                 return true;
 443         } else if (subflow->mp_join) {
 444                 opts->suboptions = OPTION_MPTCP_MPJ_ACK;
 445                 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
 446                 *size = TCPOLEN_MPTCP_MPJ_ACK;
 447                 pr_debug("subflow=%p", subflow);
 448
 449                 schedule_3rdack_retransmission(sk);
 450                 return true;
 451         }
 452         return false;
 453 }
 454
 455 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
 456                                  struct sk_buff *skb, struct mptcp_ext *ext)
 457 {
 458         /* The write_seq value has already been incremented, so the actual
 459          * sequence number for the DATA_FIN is one less.
 460          */
 461         u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
 462
 463         if (!ext->use_map || !skb->len) {
 464                 /* RFC6824 requires a DSS mapping with specific values
 465                  * if DATA_FIN is set but no data payload is mapped
 466                  */
 467                 ext->data_fin = 1;
 468                 ext->use_map = 1;
 469                 ext->dsn64 = 1;
 470                 ext->data_seq = data_fin_tx_seq;
 471                 ext->subflow_seq = 0;
 472                 ext->data_len = 1;
 473         } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
 474                 /* If there's an existing DSS mapping and it is the
 475                  * final mapping, DATA_FIN consumes 1 additional byte of
 476                  * mapping space.
 477                  */
 478                 ext->data_fin = 1;
 479                 ext->data_len++;
 480         }
 481 }
 482
 483 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 484                                           unsigned int *size,
 485                                           unsigned int remaining,
 486                                           struct mptcp_out_options *opts)
 487 {
 488         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 489         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 490         unsigned int dss_size = 0;
 491         u64 snd_data_fin_enable;
 492         struct mptcp_ext *mpext;
 493         unsigned int ack_size;
 494         bool ret = false;
 495
 496         mpext = skb ? mptcp_get_ext(skb) : NULL;
 497         snd_data_fin_enable = READ_ONCE(msk->snd_data_fin_enable);
 498
 499         if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
 500                 unsigned int map_size;
 501
 502                 map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
 503
 504                 remaining -= map_size;
 505                 dss_size = map_size;
 506                 if (mpext)
 507                         opts->ext_copy = *mpext;
 508
 509                 if (skb && snd_data_fin_enable)
 510                         mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
 511                 ret = true;
 512         }
 513
 514         /* passive sockets msk will set the 'can_ack' after accept(), even
 515          * if the first subflow may have the already the remote key handy
 516          */
 517         opts->ext_copy.use_ack = 0;
 518         if (!READ_ONCE(msk->can_ack)) {
 519                 *size = ALIGN(dss_size, 4);
 520                 return ret;
 521         }
 522
 523         if (READ_ONCE(msk->use_64bit_ack)) {
 524                 ack_size = TCPOLEN_MPTCP_DSS_ACK64;
 525                 opts->ext_copy.data_ack = READ_ONCE(msk->ack_seq);
 526                 opts->ext_copy.ack64 = 1;
 527         } else {
 528                 ack_size = TCPOLEN_MPTCP_DSS_ACK32;
 529                 opts->ext_copy.data_ack32 = (uint32_t)READ_ONCE(msk->ack_seq);
 530                 opts->ext_copy.ack64 = 0;
 531         }
 532         opts->ext_copy.use_ack = 1;
 533
 534         /* Add kind/length/subtype/flag overhead if mapping is not populated */
 535         if (dss_size == 0)
 536                 ack_size += TCPOLEN_MPTCP_DSS_BASE;
 537
 538         dss_size += ack_size;
 539
 540         *size = ALIGN(dss_size, 4);
 541         return true;
 542 }
 543
 544 static u64 add_addr_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 545                                   struct in_addr *addr)
 546 {
 547         u8 hmac[SHA256_DIGEST_SIZE];
 548         u8 msg[7];
 549
 550         msg[0] = addr_id;
 551         memcpy(&msg[1], &addr->s_addr, 4);
 552         msg[5] = 0;
 553         msg[6] = 0;
 554
 555         mptcp_crypto_hmac_sha(key1, key2, msg, 7, hmac);
 556
 557         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 558 }
 559
 560 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 561 static u64 add_addr6_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 562                                    struct in6_addr *addr)
 563 {
 564         u8 hmac[SHA256_DIGEST_SIZE];
 565         u8 msg[19];
 566
 567         msg[0] = addr_id;
 568         memcpy(&msg[1], &addr->s6_addr, 16);
 569         msg[17] = 0;
 570         msg[18] = 0;
 571
 572         mptcp_crypto_hmac_sha(key1, key2, msg, 19, hmac);
 573
 574         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 575 }
 576 #endif
 577
 578 static bool mptcp_established_options_add_addr(struct sock *sk,
 579                                                unsigned int *size,
 580                                                unsigned int remaining,
 581                                                struct mptcp_out_options *opts)
 582 {
 583         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 584         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 585         struct mptcp_addr_info saddr;
 586         bool echo;
 587         int len;
 588
 589         if (!mptcp_pm_should_add_signal(msk) ||
 590             !(mptcp_pm_add_addr_signal(msk, remaining, &saddr, &echo)))
 591                 return false;
 592
 593         len = mptcp_add_addr_len(saddr.family, echo);
 594         if (remaining < len)
 595                 return false;
 596
 597         *size = len;
 598         opts->addr_id = saddr.id;
 599         if (saddr.family == AF_INET) {
 600                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
 601                 opts->addr = saddr.addr;
 602                 if (!echo) {
 603                         opts->ahmac = add_addr_generate_hmac(msk->local_key,
 604                                                              msk->remote_key,
 605                                                              opts->addr_id,
 606                                                              &opts->addr);
 607                 }
 608         }
 609 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 610         else if (saddr.family == AF_INET6) {
 611                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR6;
 612                 opts->addr6 = saddr.addr6;
 613                 if (!echo) {
 614                         opts->ahmac = add_addr6_generate_hmac(msk->local_key,
 615                                                               msk->remote_key,
 616                                                               opts->addr_id,
 617                                                               &opts->addr6);
 618                 }
 619         }
 620 #endif
 621         pr_debug("addr_id=%d, ahmac=%llu, echo=%d", opts->addr_id, opts->ahmac, echo);
 622
 623         return true;
 624 }
 625
 626 static bool mptcp_established_options_rm_addr(struct sock *sk,
 627                                               unsigned int *size,
 628                                               unsigned int remaining,
 629                                               struct mptcp_out_options *opts)
 630 {
 631         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 632         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 633         u8 rm_id;
 634
 635         if (!mptcp_pm_should_rm_signal(msk) ||
 636             !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_id)))
 637                 return false;
 638
 639         if (remaining < TCPOLEN_MPTCP_RM_ADDR_BASE)
 640                 return false;
 641
 642         *size = TCPOLEN_MPTCP_RM_ADDR_BASE;
 643         opts->suboptions |= OPTION_MPTCP_RM_ADDR;
 644         opts->rm_id = rm_id;
 645
 646         pr_debug("rm_id=%d", opts->rm_id);
 647
 648         return true;
 649 }
 650
 651 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 652                                unsigned int *size, unsigned int remaining,
 653                                struct mptcp_out_options *opts)
 654 {
 655         unsigned int opt_size = 0;
 656         bool ret = false;
 657
 658         opts->suboptions = 0;
 659
 660         if (unlikely(mptcp_check_fallback(sk)))
 661                 return false;
 662
 663         /* prevent adding of any MPTCP related options on reset packet
 664          * until we support MP_TCPRST/MP_FASTCLOSE
 665          */
 666         if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
 667                 return false;
 668
 669         if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
 670                 ret = true;
 671         else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
 672                                                opts))
 673                 ret = true;
 674
 675         /* we reserved enough space for the above options, and exceeding the
 676          * TCP option space would be fatal
 677          */
 678         if (WARN_ON_ONCE(opt_size > remaining))
 679                 return false;
 680
 681         *size += opt_size;
 682         remaining -= opt_size;
 683         if (mptcp_established_options_add_addr(sk, &opt_size, remaining, opts)) {
 684                 *size += opt_size;
 685                 remaining -= opt_size;
 686                 ret = true;
 687         } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
 688                 *size += opt_size;
 689                 remaining -= opt_size;
 690                 ret = true;
 691         }
 692
 693         return ret;
 694 }
 695
 696 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 697                           struct mptcp_out_options *opts)
 698 {
 699         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 700
 701         if (subflow_req->mp_capable) {
 702                 opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
 703                 opts->sndr_key = subflow_req->local_key;
 704                 *size = TCPOLEN_MPTCP_MPC_SYNACK;
 705                 pr_debug("subflow_req=%p, local_key=%llu",
 706                          subflow_req, subflow_req->local_key);
 707                 return true;
 708         } else if (subflow_req->mp_join) {
 709                 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
 710                 opts->backup = subflow_req->backup;
 711                 opts->join_id = subflow_req->local_id;
 712                 opts->thmac = subflow_req->thmac;
 713                 opts->nonce = subflow_req->local_nonce;
 714                 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
 715                          subflow_req, opts->backup, opts->join_id,
 716                          opts->thmac, opts->nonce);
 717                 *size = TCPOLEN_MPTCP_MPJ_SYNACK;
 718                 return true;
 719         }
 720         return false;
 721 }
 722
 723 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
 724                                     struct mptcp_subflow_context *subflow,
 725                                     struct sk_buff *skb,
 726                                     struct mptcp_options_received *mp_opt)
 727 {
 728         /* here we can process OoO, in-window pkts, only in-sequence 4th ack
 729          * will make the subflow fully established
 730          */
 731         if (likely(subflow->fully_established)) {
 732                 /* on passive sockets, check for 3rd ack retransmission
 733                  * note that msk is always set by subflow_syn_recv_sock()
 734                  * for mp_join subflows
 735                  */
 736                 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
 737                     TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
 738                     subflow->mp_join && mp_opt->mp_join &&
 739                     READ_ONCE(msk->pm.server_side))
 740                         tcp_send_ack(ssk);
 741                 goto fully_established;
 742         }
 743
 744         /* we must process OoO packets before the first subflow is fully
 745          * established. OoO packets are instead a protocol violation
 746          * for MP_JOIN subflows as the peer must not send any data
 747          * before receiving the forth ack - cfr. RFC 8684 section 3.2.
 748          */
 749         if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
 750                 if (subflow->mp_join)
 751                         goto reset;
 752                 return subflow->mp_capable;
 753         }
 754
 755         if (mp_opt->dss && mp_opt->use_ack) {
 756                 /* subflows are fully established as soon as we get any
 757                  * additional ack.
 758                  */
 759                 subflow->fully_established = 1;
 760                 WRITE_ONCE(msk->fully_established, true);
 761                 goto fully_established;
 762         }
 763
 764         /* If the first established packet does not contain MP_CAPABLE + data
 765          * then fallback to TCP. Fallback scenarios requires a reset for
 766          * MP_JOIN subflows.
 767          */
 768         if (!mp_opt->mp_capable) {
 769                 if (subflow->mp_join)
 770                         goto reset;
 771                 subflow->mp_capable = 0;
 772                 pr_fallback(msk);
 773                 __mptcp_do_fallback(msk);
 774                 return false;
 775         }
 776
 777         if (unlikely(!READ_ONCE(msk->pm.server_side)))
 778                 pr_warn_once("bogus mpc option on established client sk");
 779         mptcp_subflow_fully_established(subflow, mp_opt);
 780
 781 fully_established:
 782         if (likely(subflow->pm_notified))
 783                 return true;
 784
 785         subflow->pm_notified = 1;
 786         if (subflow->mp_join) {
 787                 clear_3rdack_retransmission(ssk);
 788                 mptcp_pm_subflow_established(msk, subflow);
 789         } else {
 790                 mptcp_pm_fully_established(msk);
 791         }
 792         return true;
 793
 794 reset:
 795         mptcp_subflow_reset(ssk);
 796         return false;
 797 }
 798
 799 static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
 800 {
 801         u32 old_ack32, cur_ack32;
 802
 803         if (use_64bit)
 804                 return cur_ack;
 805
 806         old_ack32 = (u32)old_ack;
 807         cur_ack32 = (u32)cur_ack;
 808         cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
 809         if (unlikely(before(cur_ack32, old_ack32)))
 810                 return cur_ack + (1LL << 32);
 811         return cur_ack;
 812 }
 813
 814 static void update_una(struct mptcp_sock *msk,
 815                        struct mptcp_options_received *mp_opt)
 816 {
 817         u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
 818         u64 write_seq = READ_ONCE(msk->write_seq);
 819
 820         /* avoid ack expansion on update conflict, to reduce the risk of
 821          * wrongly expanding to a future ack sequence number, which is way
 822          * more dangerous than missing an ack
 823          */
 824         new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
 825
 826         /* ACK for data not even sent yet? Ignore. */
 827         if (after64(new_snd_una, write_seq))
 828                 new_snd_una = old_snd_una;
 829
 830         while (after64(new_snd_una, old_snd_una)) {
 831                 snd_una = old_snd_una;
 832                 old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
 833                                                new_snd_una);
 834                 if (old_snd_una == snd_una) {
 835                         mptcp_data_acked((struct sock *)msk);
 836                         break;
 837                 }
 838         }
 839 }
 840
 841 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
 842 {
 843         /* Skip if DATA_FIN was already received.
 844          * If updating simultaneously with the recvmsg loop, values
 845          * should match. If they mismatch, the peer is misbehaving and
 846          * we will prefer the most recent information.
 847          */
 848         if (READ_ONCE(msk->rcv_data_fin) || !READ_ONCE(msk->first))
 849                 return false;
 850
 851         WRITE_ONCE(msk->rcv_data_fin_seq,
 852                    expand_ack(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
 853         WRITE_ONCE(msk->rcv_data_fin, 1);
 854
 855         return true;
 856 }
 857
 858 static bool add_addr_hmac_valid(struct mptcp_sock *msk,
 859                                 struct mptcp_options_received *mp_opt)
 860 {
 861         u64 hmac = 0;
 862
 863         if (mp_opt->echo)
 864                 return true;
 865
 866         if (mp_opt->family == MPTCP_ADDR_IPVERSION_4)
 867                 hmac = add_addr_generate_hmac(msk->remote_key,
 868                                               msk->local_key,
 869                                               mp_opt->addr_id, &mp_opt->addr);
 870 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 871         else
 872                 hmac = add_addr6_generate_hmac(msk->remote_key,
 873                                                msk->local_key,
 874                                                mp_opt->addr_id, &mp_opt->addr6);
 875 #endif
 876
 877         pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
 878                  msk, (unsigned long long)hmac,
 879                  (unsigned long long)mp_opt->ahmac);
 880
 881         return hmac == mp_opt->ahmac;
 882 }
 883
 884 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 885 {
 886         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 887         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 888         struct mptcp_options_received mp_opt;
 889         struct mptcp_ext *mpext;
 890
 891         if (__mptcp_check_fallback(msk))
 892                 return;
 893
 894         mptcp_get_options(skb, &mp_opt);
 895         if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
 896                 return;
 897
 898         if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
 899                 struct mptcp_addr_info addr;
 900
 901                 addr.port = htons(mp_opt.port);
 902                 addr.id = mp_opt.addr_id;
 903                 if (mp_opt.family == MPTCP_ADDR_IPVERSION_4) {
 904                         addr.family = AF_INET;
 905                         addr.addr = mp_opt.addr;
 906                 }
 907 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 908                 else if (mp_opt.family == MPTCP_ADDR_IPVERSION_6) {
 909                         addr.family = AF_INET6;
 910                         addr.addr6 = mp_opt.addr6;
 911                 }
 912 #endif
 913                 if (!mp_opt.echo) {
 914                         mptcp_pm_add_addr_received(msk, &addr);
 915                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
 916                 } else {
 917                         mptcp_pm_del_add_timer(msk, &addr);
 918                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
 919                 }
 920                 mp_opt.add_addr = 0;
 921         }
 922
 923         if (mp_opt.rm_addr) {
 924                 mptcp_pm_rm_addr_received(msk, mp_opt.rm_id);
 925                 mp_opt.rm_addr = 0;
 926         }
 927
 928         if (!mp_opt.dss)
 929                 return;
 930
 931         /* we can't wait for recvmsg() to update the ack_seq, otherwise
 932          * monodirectional flows will stuck
 933          */
 934         if (mp_opt.use_ack)
 935                 update_una(msk, &mp_opt);
 936
 937         /* Zero-data-length packets are dropped by the caller and not
 938          * propagated to the MPTCP layer, so the skb extension does not
 939          * need to be allocated or populated. DATA_FIN information, if
 940          * present, needs to be updated here before the skb is freed.
 941          */
 942         if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
 943                 if (mp_opt.data_fin && mp_opt.data_len == 1 &&
 944                     mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
 945                     schedule_work(&msk->work))
 946                         sock_hold(subflow->conn);
 947
 948                 return;
 949         }
 950
 951         mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
 952         if (!mpext)
 953                 return;
 954
 955         memset(mpext, 0, sizeof(*mpext));
 956
 957         if (mp_opt.use_map) {
 958                 if (mp_opt.mpc_map) {
 959                         /* this is an MP_CAPABLE carrying MPTCP data
 960                          * we know this map the first chunk of data
 961                          */
 962                         mptcp_crypto_key_sha(subflow->remote_key, NULL,
 963                                              &mpext->data_seq);
 964                         mpext->data_seq++;
 965                         mpext->subflow_seq = 1;
 966                         mpext->dsn64 = 1;
 967                         mpext->mpc_map = 1;
 968                         mpext->data_fin = 0;
 969                 } else {
 970                         mpext->data_seq = mp_opt.data_seq;
 971                         mpext->subflow_seq = mp_opt.subflow_seq;
 972                         mpext->dsn64 = mp_opt.dsn64;
 973                         mpext->data_fin = mp_opt.data_fin;
 974                 }
 975                 mpext->data_len = mp_opt.data_len;
 976                 mpext->use_map = 1;
 977         }
 978 }
 979
 980 void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
 981 {
 982         if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
 983              OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
 984                 u8 len;
 985
 986                 if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
 987                         len = TCPOLEN_MPTCP_MPC_SYN;
 988                 else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
 989                         len = TCPOLEN_MPTCP_MPC_SYNACK;
 990                 else if (opts->ext_copy.data_len)
 991                         len = TCPOLEN_MPTCP_MPC_ACK_DATA;
 992                 else
 993                         len = TCPOLEN_MPTCP_MPC_ACK;
 994
 995                 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
 996                                       MPTCP_SUPPORTED_VERSION,
 997                                       MPTCP_CAP_HMAC_SHA256);
 998
 999                 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
1000                     opts->suboptions))
1001                         goto mp_capable_done;
1002
1003                 put_unaligned_be64(opts->sndr_key, ptr);
1004                 ptr += 2;
1005                 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1006                         goto mp_capable_done;
1007
1008                 put_unaligned_be64(opts->rcvr_key, ptr);
1009                 ptr += 2;
1010                 if (!opts->ext_copy.data_len)
1011                         goto mp_capable_done;
1012
1013                 put_unaligned_be32(opts->ext_copy.data_len << 16 |
1014                                    TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1015                 ptr += 1;
1016         }
1017
1018 mp_capable_done:
1019         if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
1020                 if (opts->ahmac)
1021                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1022                                               TCPOLEN_MPTCP_ADD_ADDR, 0,
1023                                               opts->addr_id);
1024                 else
1025                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1026                                               TCPOLEN_MPTCP_ADD_ADDR_BASE,
1027                                               MPTCP_ADDR_ECHO,
1028                                               opts->addr_id);
1029                 memcpy((u8 *)ptr, (u8 *)&opts->addr.s_addr, 4);
1030                 ptr += 1;
1031                 if (opts->ahmac) {
1032                         put_unaligned_be64(opts->ahmac, ptr);
1033                         ptr += 2;
1034                 }
1035         }
1036
1037 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1038         if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions) {
1039                 if (opts->ahmac)
1040                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1041                                               TCPOLEN_MPTCP_ADD_ADDR6, 0,
1042                                               opts->addr_id);
1043                 else
1044                         *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1045                                               TCPOLEN_MPTCP_ADD_ADDR6_BASE,
1046                                               MPTCP_ADDR_ECHO,
1047                                               opts->addr_id);
1048                 memcpy((u8 *)ptr, opts->addr6.s6_addr, 16);
1049                 ptr += 4;
1050                 if (opts->ahmac) {
1051                         put_unaligned_be64(opts->ahmac, ptr);
1052                         ptr += 2;
1053                 }
1054         }
1055 #endif
1056
1057         if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1058                 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1059                                       TCPOLEN_MPTCP_RM_ADDR_BASE,
1060                                       0, opts->rm_id);
1061         }
1062
1063         if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1064                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1065                                       TCPOLEN_MPTCP_MPJ_SYN,
1066                                       opts->backup, opts->join_id);
1067                 put_unaligned_be32(opts->token, ptr);
1068                 ptr += 1;
1069                 put_unaligned_be32(opts->nonce, ptr);
1070                 ptr += 1;
1071         }
1072
1073         if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1074                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1075                                       TCPOLEN_MPTCP_MPJ_SYNACK,
1076                                       opts->backup, opts->join_id);
1077                 put_unaligned_be64(opts->thmac, ptr);
1078                 ptr += 2;
1079                 put_unaligned_be32(opts->nonce, ptr);
1080                 ptr += 1;
1081         }
1082
1083         if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1084                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1085                                       TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1086                 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1087                 ptr += 5;
1088         }
1089
1090         if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
1091                 struct mptcp_ext *mpext = &opts->ext_copy;
1092                 u8 len = TCPOLEN_MPTCP_DSS_BASE;
1093                 u8 flags = 0;
1094
1095                 if (mpext->use_ack) {
1096                         flags = MPTCP_DSS_HAS_ACK;
1097                         if (mpext->ack64) {
1098                                 len += TCPOLEN_MPTCP_DSS_ACK64;
1099                                 flags |= MPTCP_DSS_ACK64;
1100                         } else {
1101                                 len += TCPOLEN_MPTCP_DSS_ACK32;
1102                         }
1103                 }
1104
1105                 if (mpext->use_map) {
1106                         len += TCPOLEN_MPTCP_DSS_MAP64;
1107
1108                         /* Use only 64-bit mapping flags for now, add
1109                          * support for optional 32-bit mappings later.
1110                          */
1111                         flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1112                         if (mpext->data_fin)
1113                                 flags |= MPTCP_DSS_DATA_FIN;
1114                 }
1115
1116                 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
1117
1118                 if (mpext->use_ack) {
1119                         if (mpext->ack64) {
1120                                 put_unaligned_be64(mpext->data_ack, ptr);
1121                                 ptr += 2;
1122                         } else {
1123                                 put_unaligned_be32(mpext->data_ack32, ptr);
1124                                 ptr += 1;
1125                         }
1126                 }
1127
1128                 if (mpext->use_map) {
1129                         put_unaligned_be64(mpext->data_seq, ptr);
1130                         ptr += 2;
1131                         put_unaligned_be32(mpext->subflow_seq, ptr);
1132                         ptr += 1;
1133                         put_unaligned_be32(mpext->data_len << 16 |
1134                                            TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1135                 }
1136         }
1137 }