net/mptcp/options.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Multipath TCP
   3  *
   4  * Copyright (c) 2017 - 2019, Intel Corporation.
   5  */
   6
   7 #define pr_fmt(fmt) "MPTCP: " fmt
   8
   9 #include <linux/kernel.h>
  10 #include <crypto/sha2.h>
  11 #include <net/tcp.h>
  12 #include <net/mptcp.h>
  13 #include "protocol.h"
  14 #include "mib.h"
  15
  16 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                 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                 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d",
 270                          (mp_opt->family == MPTCP_ADDR_IPVERSION_6) ? "6" : "",
 271                          mp_opt->addr_id, mp_opt->ahmac, mp_opt->echo, mp_opt->port);
 272                 break;
 273
 274         case MPTCPOPT_RM_ADDR:
 275                 if (opsize != TCPOLEN_MPTCP_RM_ADDR_BASE)
 276                         break;
 277
 278                 ptr++;
 279
 280                 mp_opt->rm_addr = 1;
 281                 mp_opt->rm_id = *ptr++;
 282                 pr_debug("RM_ADDR: id=%d", mp_opt->rm_id);
 283                 break;
 284
 285         case MPTCPOPT_MP_FASTCLOSE:
 286                 if (opsize != TCPOLEN_MPTCP_FASTCLOSE)
 287                         break;
 288
 289                 ptr += 2;
 290                 mp_opt->rcvr_key = get_unaligned_be64(ptr);
 291                 ptr += 8;
 292                 mp_opt->fastclose = 1;
 293                 break;
 294
 295         default:
 296                 break;
 297         }
 298 }
 299
 300 void mptcp_get_options(const struct sk_buff *skb,
 301                        struct mptcp_options_received *mp_opt)
 302 {
 303         const struct tcphdr *th = tcp_hdr(skb);
 304         const unsigned char *ptr;
 305         int length;
 306
 307         /* initialize option status */
 308         mp_opt->mp_capable = 0;
 309         mp_opt->mp_join = 0;
 310         mp_opt->add_addr = 0;
 311         mp_opt->ahmac = 0;
 312         mp_opt->fastclose = 0;
 313         mp_opt->port = 0;
 314         mp_opt->rm_addr = 0;
 315         mp_opt->dss = 0;
 316
 317         length = (th->doff * 4) - sizeof(struct tcphdr);
 318         ptr = (const unsigned char *)(th + 1);
 319
 320         while (length > 0) {
 321                 int opcode = *ptr++;
 322                 int opsize;
 323
 324                 switch (opcode) {
 325                 case TCPOPT_EOL:
 326                         return;
 327                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 328                         length--;
 329                         continue;
 330                 default:
 331                         opsize = *ptr++;
 332                         if (opsize < 2) /* "silly options" */
 333                                 return;
 334                         if (opsize > length)
 335                                 return; /* don't parse partial options */
 336                         if (opcode == TCPOPT_MPTCP)
 337                                 mptcp_parse_option(skb, ptr, opsize, mp_opt);
 338                         ptr += opsize - 2;
 339                         length -= opsize;
 340                 }
 341         }
 342 }
 343
 344 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 345                        unsigned int *size, struct mptcp_out_options *opts)
 346 {
 347         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 348
 349         /* we will use snd_isn to detect first pkt [re]transmission
 350          * in mptcp_established_options_mp()
 351          */
 352         subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
 353         if (subflow->request_mptcp) {
 354                 opts->suboptions = OPTION_MPTCP_MPC_SYN;
 355                 *size = TCPOLEN_MPTCP_MPC_SYN;
 356                 return true;
 357         } else if (subflow->request_join) {
 358                 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
 359                          subflow->local_nonce);
 360                 opts->suboptions = OPTION_MPTCP_MPJ_SYN;
 361                 opts->join_id = subflow->local_id;
 362                 opts->token = subflow->remote_token;
 363                 opts->nonce = subflow->local_nonce;
 364                 opts->backup = subflow->request_bkup;
 365                 *size = TCPOLEN_MPTCP_MPJ_SYN;
 366                 return true;
 367         }
 368         return false;
 369 }
 370
 371 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
 372  * TCP can't schedule delack timer before the subflow is fully established.
 373  * MPTCP uses the delack timer to do 3rd ack retransmissions
 374  */
 375 static void schedule_3rdack_retransmission(struct sock *sk)
 376 {
 377         struct inet_connection_sock *icsk = inet_csk(sk);
 378         struct tcp_sock *tp = tcp_sk(sk);
 379         unsigned long timeout;
 380
 381         /* reschedule with a timeout above RTT, as we must look only for drop */
 382         if (tp->srtt_us)
 383                 timeout = tp->srtt_us << 1;
 384         else
 385                 timeout = TCP_TIMEOUT_INIT;
 386
 387         WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
 388         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 389         icsk->icsk_ack.timeout = timeout;
 390         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 391 }
 392
 393 static void clear_3rdack_retransmission(struct sock *sk)
 394 {
 395         struct inet_connection_sock *icsk = inet_csk(sk);
 396
 397         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 398         icsk->icsk_ack.timeout = 0;
 399         icsk->icsk_ack.ato = 0;
 400         icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
 401 }
 402
 403 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 404                                          unsigned int *size,
 405                                          unsigned int remaining,
 406                                          struct mptcp_out_options *opts)
 407 {
 408         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 409         struct mptcp_ext *mpext;
 410         unsigned int data_len;
 411
 412         /* When skb is not available, we better over-estimate the emitted
 413          * options len. A full DSS option (28 bytes) is longer than
 414          * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
 415          * tell the caller to defer the estimate to
 416          * mptcp_established_options_dss(), which will reserve enough space.
 417          */
 418         if (!skb)
 419                 return false;
 420
 421         /* MPC/MPJ needed only on 3rd ack packet */
 422         if (subflow->fully_established ||
 423             subflow->snd_isn != TCP_SKB_CB(skb)->seq)
 424                 return false;
 425
 426         if (subflow->mp_capable) {
 427                 mpext = mptcp_get_ext(skb);
 428                 data_len = mpext ? mpext->data_len : 0;
 429
 430                 /* we will check ext_copy.data_len in mptcp_write_options() to
 431                  * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
 432                  * TCPOLEN_MPTCP_MPC_ACK
 433                  */
 434                 opts->ext_copy.data_len = data_len;
 435                 opts->suboptions = OPTION_MPTCP_MPC_ACK;
 436                 opts->sndr_key = subflow->local_key;
 437                 opts->rcvr_key = subflow->remote_key;
 438
 439                 /* Section 3.1.
 440                  * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
 441                  * packets that start the first subflow of an MPTCP connection,
 442                  * as well as the first packet that carries data
 443                  */
 444                 if (data_len > 0)
 445                         *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
 446                 else
 447                         *size = TCPOLEN_MPTCP_MPC_ACK;
 448
 449                 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
 450                          subflow, subflow->local_key, subflow->remote_key,
 451                          data_len);
 452
 453                 return true;
 454         } else if (subflow->mp_join) {
 455                 opts->suboptions = OPTION_MPTCP_MPJ_ACK;
 456                 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
 457                 *size = TCPOLEN_MPTCP_MPJ_ACK;
 458                 pr_debug("subflow=%p", subflow);
 459
 460                 schedule_3rdack_retransmission(sk);
 461                 return true;
 462         }
 463         return false;
 464 }
 465
 466 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
 467                                  struct sk_buff *skb, struct mptcp_ext *ext)
 468 {
 469         /* The write_seq value has already been incremented, so the actual
 470          * sequence number for the DATA_FIN is one less.
 471          */
 472         u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
 473
 474         if (!ext->use_map || !skb->len) {
 475                 /* RFC6824 requires a DSS mapping with specific values
 476                  * if DATA_FIN is set but no data payload is mapped
 477                  */
 478                 ext->data_fin = 1;
 479                 ext->use_map = 1;
 480                 ext->dsn64 = 1;
 481                 ext->data_seq = data_fin_tx_seq;
 482                 ext->subflow_seq = 0;
 483                 ext->data_len = 1;
 484         } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
 485                 /* If there's an existing DSS mapping and it is the
 486                  * final mapping, DATA_FIN consumes 1 additional byte of
 487                  * mapping space.
 488                  */
 489                 ext->data_fin = 1;
 490                 ext->data_len++;
 491         }
 492 }
 493
 494 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 495                                           unsigned int *size,
 496                                           unsigned int remaining,
 497                                           struct mptcp_out_options *opts)
 498 {
 499         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 500         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 501         unsigned int dss_size = 0;
 502         u64 snd_data_fin_enable;
 503         struct mptcp_ext *mpext;
 504         unsigned int ack_size;
 505         bool ret = false;
 506
 507         mpext = skb ? mptcp_get_ext(skb) : NULL;
 508         snd_data_fin_enable = mptcp_data_fin_enabled(msk);
 509
 510         if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
 511                 unsigned int map_size;
 512
 513                 map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
 514
 515                 remaining -= map_size;
 516                 dss_size = map_size;
 517                 if (mpext)
 518                         opts->ext_copy = *mpext;
 519
 520                 if (skb && snd_data_fin_enable)
 521                         mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
 522                 ret = true;
 523         }
 524
 525         /* passive sockets msk will set the 'can_ack' after accept(), even
 526          * if the first subflow may have the already the remote key handy
 527          */
 528         opts->ext_copy.use_ack = 0;
 529         if (!READ_ONCE(msk->can_ack)) {
 530                 *size = ALIGN(dss_size, 4);
 531                 return ret;
 532         }
 533
 534         if (READ_ONCE(msk->use_64bit_ack)) {
 535                 ack_size = TCPOLEN_MPTCP_DSS_ACK64;
 536                 opts->ext_copy.data_ack = READ_ONCE(msk->ack_seq);
 537                 opts->ext_copy.ack64 = 1;
 538         } else {
 539                 ack_size = TCPOLEN_MPTCP_DSS_ACK32;
 540                 opts->ext_copy.data_ack32 = (uint32_t)READ_ONCE(msk->ack_seq);
 541                 opts->ext_copy.ack64 = 0;
 542         }
 543         opts->ext_copy.use_ack = 1;
 544         WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
 545
 546         /* Add kind/length/subtype/flag overhead if mapping is not populated */
 547         if (dss_size == 0)
 548                 ack_size += TCPOLEN_MPTCP_DSS_BASE;
 549
 550         dss_size += ack_size;
 551
 552         *size = ALIGN(dss_size, 4);
 553         return true;
 554 }
 555
 556 static u64 add_addr_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 557                                   struct in_addr *addr)
 558 {
 559         u8 hmac[SHA256_DIGEST_SIZE];
 560         u8 msg[7];
 561
 562         msg[0] = addr_id;
 563         memcpy(&msg[1], &addr->s_addr, 4);
 564         msg[5] = 0;
 565         msg[6] = 0;
 566
 567         mptcp_crypto_hmac_sha(key1, key2, msg, 7, hmac);
 568
 569         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 570 }
 571
 572 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 573 static u64 add_addr6_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 574                                    struct in6_addr *addr)
 575 {
 576         u8 hmac[SHA256_DIGEST_SIZE];
 577         u8 msg[19];
 578
 579         msg[0] = addr_id;
 580         memcpy(&msg[1], &addr->s6_addr, 16);
 581         msg[17] = 0;
 582         msg[18] = 0;
 583
 584         mptcp_crypto_hmac_sha(key1, key2, msg, 19, hmac);
 585
 586         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 587 }
 588 #endif
 589
 590 static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb,
 591                                                unsigned int *size,
 592                                                unsigned int remaining,
 593                                                struct mptcp_out_options *opts)
 594 {
 595         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 596         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 597         bool drop_other_suboptions = false;
 598         unsigned int opt_size = *size;
 599         struct mptcp_addr_info saddr;
 600         bool echo;
 601         bool port;
 602         int len;
 603
 604         if ((mptcp_pm_should_add_signal_ipv6(msk) ||
 605              mptcp_pm_should_add_signal_port(msk)) &&
 606             skb && skb_is_tcp_pure_ack(skb)) {
 607                 pr_debug("drop other suboptions");
 608                 opts->suboptions = 0;
 609                 opts->ext_copy.use_ack = 0;
 610                 opts->ext_copy.use_map = 0;
 611                 remaining += opt_size;
 612                 drop_other_suboptions = true;
 613         }
 614
 615         if (!mptcp_pm_should_add_signal(msk) ||
 616             !(mptcp_pm_add_addr_signal(msk, remaining, &saddr, &echo, &port)))
 617                 return false;
 618
 619         len = mptcp_add_addr_len(saddr.family, echo, port);
 620         if (remaining < len)
 621                 return false;
 622
 623         *size = len;
 624         if (drop_other_suboptions)
 625                 *size -= opt_size;
 626         opts->addr_id = saddr.id;
 627         if (port)
 628                 opts->port = ntohs(saddr.port);
 629         if (saddr.family == AF_INET) {
 630                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
 631                 opts->addr = saddr.addr;
 632                 if (!echo) {
 633                         opts->ahmac = add_addr_generate_hmac(msk->local_key,
 634                                                              msk->remote_key,
 635                                                              opts->addr_id,
 636                                                              &opts->addr);
 637                 }
 638         }
 639 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 640         else if (saddr.family == AF_INET6) {
 641                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR6;
 642                 opts->addr6 = saddr.addr6;
 643                 if (!echo) {
 644                         opts->ahmac = add_addr6_generate_hmac(msk->local_key,
 645                                                               msk->remote_key,
 646                                                               opts->addr_id,
 647                                                               &opts->addr6);
 648                 }
 649         }
 650 #endif
 651         pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
 652                  opts->addr_id, opts->ahmac, echo, opts->port);
 653
 654         return true;
 655 }
 656
 657 static bool mptcp_established_options_rm_addr(struct sock *sk,
 658                                               unsigned int *size,
 659                                               unsigned int remaining,
 660                                               struct mptcp_out_options *opts)
 661 {
 662         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 663         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 664         u8 rm_id;
 665
 666         if (!mptcp_pm_should_rm_signal(msk) ||
 667             !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_id)))
 668                 return false;
 669
 670         if (remaining < TCPOLEN_MPTCP_RM_ADDR_BASE)
 671                 return false;
 672
 673         *size = TCPOLEN_MPTCP_RM_ADDR_BASE;
 674         opts->suboptions |= OPTION_MPTCP_RM_ADDR;
 675         opts->rm_id = rm_id;
 676
 677         pr_debug("rm_id=%d", opts->rm_id);
 678
 679         return true;
 680 }
 681
 682 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 683                                unsigned int *size, unsigned int remaining,
 684                                struct mptcp_out_options *opts)
 685 {
 686         unsigned int opt_size = 0;
 687         bool ret = false;
 688
 689         opts->suboptions = 0;
 690
 691         if (unlikely(mptcp_check_fallback(sk)))
 692                 return false;
 693
 694         /* prevent adding of any MPTCP related options on reset packet
 695          * until we support MP_TCPRST/MP_FASTCLOSE
 696          */
 697         if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
 698                 return false;
 699
 700         if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
 701                 ret = true;
 702         else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
 703                                                opts))
 704                 ret = true;
 705
 706         /* we reserved enough space for the above options, and exceeding the
 707          * TCP option space would be fatal
 708          */
 709         if (WARN_ON_ONCE(opt_size > remaining))
 710                 return false;
 711
 712         *size += opt_size;
 713         remaining -= opt_size;
 714         if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
 715                 *size += opt_size;
 716                 remaining -= opt_size;
 717                 ret = true;
 718         } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
 719                 *size += opt_size;
 720                 remaining -= opt_size;
 721                 ret = true;
 722         }
 723
 724         return ret;
 725 }
 726
 727 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 728                           struct mptcp_out_options *opts)
 729 {
 730         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 731
 732         if (subflow_req->mp_capable) {
 733                 opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
 734                 opts->sndr_key = subflow_req->local_key;
 735                 *size = TCPOLEN_MPTCP_MPC_SYNACK;
 736                 pr_debug("subflow_req=%p, local_key=%llu",
 737                          subflow_req, subflow_req->local_key);
 738                 return true;
 739         } else if (subflow_req->mp_join) {
 740                 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
 741                 opts->backup = subflow_req->backup;
 742                 opts->join_id = subflow_req->local_id;
 743                 opts->thmac = subflow_req->thmac;
 744                 opts->nonce = subflow_req->local_nonce;
 745                 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
 746                          subflow_req, opts->backup, opts->join_id,
 747                          opts->thmac, opts->nonce);
 748                 *size = TCPOLEN_MPTCP_MPJ_SYNACK;
 749                 return true;
 750         }
 751         return false;
 752 }
 753
 754 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
 755                                     struct mptcp_subflow_context *subflow,
 756                                     struct sk_buff *skb,
 757                                     struct mptcp_options_received *mp_opt)
 758 {
 759         /* here we can process OoO, in-window pkts, only in-sequence 4th ack
 760          * will make the subflow fully established
 761          */
 762         if (likely(subflow->fully_established)) {
 763                 /* on passive sockets, check for 3rd ack retransmission
 764                  * note that msk is always set by subflow_syn_recv_sock()
 765                  * for mp_join subflows
 766                  */
 767                 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
 768                     TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
 769                     subflow->mp_join && mp_opt->mp_join &&
 770                     READ_ONCE(msk->pm.server_side))
 771                         tcp_send_ack(ssk);
 772                 goto fully_established;
 773         }
 774
 775         /* we must process OoO packets before the first subflow is fully
 776          * established. OoO packets are instead a protocol violation
 777          * for MP_JOIN subflows as the peer must not send any data
 778          * before receiving the forth ack - cfr. RFC 8684 section 3.2.
 779          */
 780         if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
 781                 if (subflow->mp_join)
 782                         goto reset;
 783                 return subflow->mp_capable;
 784         }
 785
 786         if (mp_opt->dss && mp_opt->use_ack) {
 787                 /* subflows are fully established as soon as we get any
 788                  * additional ack.
 789                  */
 790                 subflow->fully_established = 1;
 791                 WRITE_ONCE(msk->fully_established, true);
 792                 goto fully_established;
 793         }
 794
 795         if (mp_opt->add_addr) {
 796                 WRITE_ONCE(msk->fully_established, true);
 797                 return true;
 798         }
 799
 800         /* If the first established packet does not contain MP_CAPABLE + data
 801          * then fallback to TCP. Fallback scenarios requires a reset for
 802          * MP_JOIN subflows.
 803          */
 804         if (!mp_opt->mp_capable) {
 805                 if (subflow->mp_join)
 806                         goto reset;
 807                 subflow->mp_capable = 0;
 808                 pr_fallback(msk);
 809                 __mptcp_do_fallback(msk);
 810                 return false;
 811         }
 812
 813         if (unlikely(!READ_ONCE(msk->pm.server_side)))
 814                 pr_warn_once("bogus mpc option on established client sk");
 815         mptcp_subflow_fully_established(subflow, mp_opt);
 816
 817 fully_established:
 818         /* if the subflow is not already linked into the conn_list, we can't
 819          * notify the PM: this subflow is still on the listener queue
 820          * and the PM possibly acquiring the subflow lock could race with
 821          * the listener close
 822          */
 823         if (likely(subflow->pm_notified) || list_empty(&subflow->node))
 824                 return true;
 825
 826         subflow->pm_notified = 1;
 827         if (subflow->mp_join) {
 828                 clear_3rdack_retransmission(ssk);
 829                 mptcp_pm_subflow_established(msk, subflow);
 830         } else {
 831                 mptcp_pm_fully_established(msk);
 832         }
 833         return true;
 834
 835 reset:
 836         mptcp_subflow_reset(ssk);
 837         return false;
 838 }
 839
 840 static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
 841 {
 842         u32 old_ack32, cur_ack32;
 843
 844         if (use_64bit)
 845                 return cur_ack;
 846
 847         old_ack32 = (u32)old_ack;
 848         cur_ack32 = (u32)cur_ack;
 849         cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
 850         if (unlikely(before(cur_ack32, old_ack32)))
 851                 return cur_ack + (1LL << 32);
 852         return cur_ack;
 853 }
 854
 855 static void ack_update_msk(struct mptcp_sock *msk,
 856                            struct sock *ssk,
 857                            struct mptcp_options_received *mp_opt)
 858 {
 859         u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt);
 860         struct sock *sk = (struct sock *)msk;
 861         u64 old_snd_una;
 862
 863         mptcp_data_lock(sk);
 864
 865         /* avoid ack expansion on update conflict, to reduce the risk of
 866          * wrongly expanding to a future ack sequence number, which is way
 867          * more dangerous than missing an ack
 868          */
 869         old_snd_una = msk->snd_una;
 870         new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
 871
 872         /* ACK for data not even sent yet? Ignore. */
 873         if (after64(new_snd_una, snd_nxt))
 874                 new_snd_una = old_snd_una;
 875
 876         new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
 877
 878         if (after64(new_wnd_end, msk->wnd_end))
 879                 msk->wnd_end = new_wnd_end;
 880
 881         /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
 882         if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)) &&
 883             sk_stream_memory_free(ssk))
 884                 __mptcp_check_push(sk, ssk);
 885
 886         if (after64(new_snd_una, old_snd_una)) {
 887                 msk->snd_una = new_snd_una;
 888                 __mptcp_data_acked(sk);
 889         }
 890         mptcp_data_unlock(sk);
 891 }
 892
 893 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
 894 {
 895         /* Skip if DATA_FIN was already received.
 896          * If updating simultaneously with the recvmsg loop, values
 897          * should match. If they mismatch, the peer is misbehaving and
 898          * we will prefer the most recent information.
 899          */
 900         if (READ_ONCE(msk->rcv_data_fin) || !READ_ONCE(msk->first))
 901                 return false;
 902
 903         WRITE_ONCE(msk->rcv_data_fin_seq,
 904                    expand_ack(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
 905         WRITE_ONCE(msk->rcv_data_fin, 1);
 906
 907         return true;
 908 }
 909
 910 static bool add_addr_hmac_valid(struct mptcp_sock *msk,
 911                                 struct mptcp_options_received *mp_opt)
 912 {
 913         u64 hmac = 0;
 914
 915         if (mp_opt->echo)
 916                 return true;
 917
 918         if (mp_opt->family == MPTCP_ADDR_IPVERSION_4)
 919                 hmac = add_addr_generate_hmac(msk->remote_key,
 920                                               msk->local_key,
 921                                               mp_opt->addr_id, &mp_opt->addr);
 922 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 923         else
 924                 hmac = add_addr6_generate_hmac(msk->remote_key,
 925                                                msk->local_key,
 926                                                mp_opt->addr_id, &mp_opt->addr6);
 927 #endif
 928
 929         pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
 930                  msk, (unsigned long long)hmac,
 931                  (unsigned long long)mp_opt->ahmac);
 932
 933         return hmac == mp_opt->ahmac;
 934 }
 935
 936 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 937 {
 938         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 939         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 940         struct mptcp_options_received mp_opt;
 941         struct mptcp_ext *mpext;
 942
 943         if (__mptcp_check_fallback(msk)) {
 944                 /* Keep it simple and unconditionally trigger send data cleanup and
 945                  * pending queue spooling. We will need to acquire the data lock
 946                  * for more accurate checks, and once the lock is acquired, such
 947                  * helpers are cheap.
 948                  */
 949                 mptcp_data_lock(subflow->conn);
 950                 if (sk_stream_memory_free(sk))
 951                         __mptcp_check_push(subflow->conn, sk);
 952                 __mptcp_data_acked(subflow->conn);
 953                 mptcp_data_unlock(subflow->conn);
 954                 return;
 955         }
 956
 957         mptcp_get_options(skb, &mp_opt);
 958         if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
 959                 return;
 960
 961         if (mp_opt.fastclose &&
 962             msk->local_key == mp_opt.rcvr_key) {
 963                 WRITE_ONCE(msk->rcv_fastclose, true);
 964                 mptcp_schedule_work((struct sock *)msk);
 965         }
 966
 967         if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
 968                 struct mptcp_addr_info addr;
 969
 970                 addr.port = htons(mp_opt.port);
 971                 addr.id = mp_opt.addr_id;
 972                 if (mp_opt.family == MPTCP_ADDR_IPVERSION_4) {
 973                         addr.family = AF_INET;
 974                         addr.addr = mp_opt.addr;
 975                 }
 976 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 977                 else if (mp_opt.family == MPTCP_ADDR_IPVERSION_6) {
 978                         addr.family = AF_INET6;
 979                         addr.addr6 = mp_opt.addr6;
 980                 }
 981 #endif
 982                 if (!mp_opt.echo) {
 983                         mptcp_pm_add_addr_received(msk, &addr);
 984                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
 985                 } else {
 986                         mptcp_pm_del_add_timer(msk, &addr);
 987                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
 988                 }
 989                 mp_opt.add_addr = 0;
 990         }
 991
 992         if (mp_opt.rm_addr) {
 993                 mptcp_pm_rm_addr_received(msk, mp_opt.rm_id);
 994                 mp_opt.rm_addr = 0;
 995         }
 996
 997         if (!mp_opt.dss)
 998                 return;
 999
1000         /* we can't wait for recvmsg() to update the ack_seq, otherwise
1001          * monodirectional flows will stuck
1002          */
1003         if (mp_opt.use_ack)
1004                 ack_update_msk(msk, sk, &mp_opt);
1005
1006         /* Zero-data-length packets are dropped by the caller and not
1007          * propagated to the MPTCP layer, so the skb extension does not
1008          * need to be allocated or populated. DATA_FIN information, if
1009          * present, needs to be updated here before the skb is freed.
1010          */
1011         if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
1012                 if (mp_opt.data_fin && mp_opt.data_len == 1 &&
1013                     mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
1014                     schedule_work(&msk->work))
1015                         sock_hold(subflow->conn);
1016
1017                 return;
1018         }
1019
1020         mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
1021         if (!mpext)
1022                 return;
1023
1024         memset(mpext, 0, sizeof(*mpext));
1025
1026         if (mp_opt.use_map) {
1027                 if (mp_opt.mpc_map) {
1028                         /* this is an MP_CAPABLE carrying MPTCP data
1029                          * we know this map the first chunk of data
1030                          */
1031                         mptcp_crypto_key_sha(subflow->remote_key, NULL,
1032                                              &mpext->data_seq);
1033                         mpext->data_seq++;
1034                         mpext->subflow_seq = 1;
1035                         mpext->dsn64 = 1;
1036                         mpext->mpc_map = 1;
1037                         mpext->data_fin = 0;
1038                 } else {
1039                         mpext->data_seq = mp_opt.data_seq;
1040                         mpext->subflow_seq = mp_opt.subflow_seq;
1041                         mpext->dsn64 = mp_opt.dsn64;
1042                         mpext->data_fin = mp_opt.data_fin;
1043                 }
1044                 mpext->data_len = mp_opt.data_len;
1045                 mpext->use_map = 1;
1046         }
1047 }
1048
1049 static void mptcp_set_rwin(const struct tcp_sock *tp)
1050 {
1051         const struct sock *ssk = (const struct sock *)tp;
1052         const struct mptcp_subflow_context *subflow;
1053         struct mptcp_sock *msk;
1054         u64 ack_seq;
1055
1056         subflow = mptcp_subflow_ctx(ssk);
1057         msk = mptcp_sk(subflow->conn);
1058
1059         ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd;
1060
1061         if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent)))
1062                 WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
1063 }
1064
1065 void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
1066                          struct mptcp_out_options *opts)
1067 {
1068         if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
1069              OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
1070                 u8 len;
1071
1072                 if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
1073                         len = TCPOLEN_MPTCP_MPC_SYN;
1074                 else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
1075                         len = TCPOLEN_MPTCP_MPC_SYNACK;
1076                 else if (opts->ext_copy.data_len)
1077                         len = TCPOLEN_MPTCP_MPC_ACK_DATA;
1078                 else
1079                         len = TCPOLEN_MPTCP_MPC_ACK;
1080
1081                 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
1082                                       MPTCP_SUPPORTED_VERSION,
1083                                       MPTCP_CAP_HMAC_SHA256);
1084
1085                 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
1086                     opts->suboptions))
1087                         goto mp_capable_done;
1088
1089                 put_unaligned_be64(opts->sndr_key, ptr);
1090                 ptr += 2;
1091                 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1092                         goto mp_capable_done;
1093
1094                 put_unaligned_be64(opts->rcvr_key, ptr);
1095                 ptr += 2;
1096                 if (!opts->ext_copy.data_len)
1097                         goto mp_capable_done;
1098
1099                 put_unaligned_be32(opts->ext_copy.data_len << 16 |
1100                                    TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1101                 ptr += 1;
1102         }
1103
1104 mp_capable_done:
1105         if ((OPTION_MPTCP_ADD_ADDR
1106 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1107              | OPTION_MPTCP_ADD_ADDR6
1108 #endif
1109             ) & opts->suboptions) {
1110                 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
1111                 u8 echo = MPTCP_ADDR_ECHO;
1112
1113 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1114                 if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions)
1115                         len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
1116 #endif
1117
1118                 if (opts->port)
1119                         len += TCPOLEN_MPTCP_PORT_LEN;
1120
1121                 if (opts->ahmac) {
1122                         len += sizeof(opts->ahmac);
1123                         echo = 0;
1124                 }
1125
1126                 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1127                                       len, echo, opts->addr_id);
1128                 if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
1129                         memcpy((u8 *)ptr, (u8 *)&opts->addr.s_addr, 4);
1130                         ptr += 1;
1131                 }
1132 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1133                 else if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions) {
1134                         memcpy((u8 *)ptr, opts->addr6.s6_addr, 16);
1135                         ptr += 4;
1136                 }
1137 #endif
1138
1139                 if (!opts->port) {
1140                         if (opts->ahmac) {
1141                                 put_unaligned_be64(opts->ahmac, ptr);
1142                                 ptr += 2;
1143                         }
1144                 } else {
1145                         if (opts->ahmac) {
1146                                 u8 *bptr = (u8 *)ptr;
1147
1148                                 put_unaligned_be16(opts->port, bptr);
1149                                 bptr += 2;
1150                                 put_unaligned_be64(opts->ahmac, bptr);
1151                                 bptr += 8;
1152                                 put_unaligned_be16(TCPOPT_NOP << 8 |
1153                                                    TCPOPT_NOP, bptr);
1154
1155                                 ptr += 3;
1156                         } else {
1157                                 put_unaligned_be32(opts->port << 16 |
1158                                                    TCPOPT_NOP << 8 |
1159                                                    TCPOPT_NOP, ptr);
1160                                 ptr += 1;
1161                         }
1162                 }
1163         }
1164
1165         if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1166                 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1167                                       TCPOLEN_MPTCP_RM_ADDR_BASE,
1168                                       0, opts->rm_id);
1169         }
1170
1171         if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1172                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1173                                       TCPOLEN_MPTCP_MPJ_SYN,
1174                                       opts->backup, opts->join_id);
1175                 put_unaligned_be32(opts->token, ptr);
1176                 ptr += 1;
1177                 put_unaligned_be32(opts->nonce, ptr);
1178                 ptr += 1;
1179         }
1180
1181         if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1182                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1183                                       TCPOLEN_MPTCP_MPJ_SYNACK,
1184                                       opts->backup, opts->join_id);
1185                 put_unaligned_be64(opts->thmac, ptr);
1186                 ptr += 2;
1187                 put_unaligned_be32(opts->nonce, ptr);
1188                 ptr += 1;
1189         }
1190
1191         if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1192                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1193                                       TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1194                 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1195                 ptr += 5;
1196         }
1197
1198         if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
1199                 struct mptcp_ext *mpext = &opts->ext_copy;
1200                 u8 len = TCPOLEN_MPTCP_DSS_BASE;
1201                 u8 flags = 0;
1202
1203                 if (mpext->use_ack) {
1204                         flags = MPTCP_DSS_HAS_ACK;
1205                         if (mpext->ack64) {
1206                                 len += TCPOLEN_MPTCP_DSS_ACK64;
1207                                 flags |= MPTCP_DSS_ACK64;
1208                         } else {
1209                                 len += TCPOLEN_MPTCP_DSS_ACK32;
1210                         }
1211                 }
1212
1213                 if (mpext->use_map) {
1214                         len += TCPOLEN_MPTCP_DSS_MAP64;
1215
1216                         /* Use only 64-bit mapping flags for now, add
1217                          * support for optional 32-bit mappings later.
1218                          */
1219                         flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1220                         if (mpext->data_fin)
1221                                 flags |= MPTCP_DSS_DATA_FIN;
1222                 }
1223
1224                 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
1225
1226                 if (mpext->use_ack) {
1227                         if (mpext->ack64) {
1228                                 put_unaligned_be64(mpext->data_ack, ptr);
1229                                 ptr += 2;
1230                         } else {
1231                                 put_unaligned_be32(mpext->data_ack32, ptr);
1232                                 ptr += 1;
1233                         }
1234                 }
1235
1236                 if (mpext->use_map) {
1237                         put_unaligned_be64(mpext->data_seq, ptr);
1238                         ptr += 2;
1239                         put_unaligned_be32(mpext->subflow_seq, ptr);
1240                         ptr += 1;
1241                         put_unaligned_be32(mpext->data_len << 16 |
1242                                            TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1243                 }
1244         }
1245
1246         if (tp)
1247                 mptcp_set_rwin(tp);
1248 }