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_PRIO:
 286                 if (opsize != TCPOLEN_MPTCP_PRIO)
 287                         break;
 288
 289                 mp_opt->mp_prio = 1;
 290                 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP;
 291                 pr_debug("MP_PRIO: prio=%d", mp_opt->backup);
 292                 break;
 293
 294         case MPTCPOPT_MP_FASTCLOSE:
 295                 if (opsize != TCPOLEN_MPTCP_FASTCLOSE)
 296                         break;
 297
 298                 ptr += 2;
 299                 mp_opt->rcvr_key = get_unaligned_be64(ptr);
 300                 ptr += 8;
 301                 mp_opt->fastclose = 1;
 302                 break;
 303
 304         default:
 305                 break;
 306         }
 307 }
 308
 309 void mptcp_get_options(const struct sk_buff *skb,
 310                        struct mptcp_options_received *mp_opt)
 311 {
 312         const struct tcphdr *th = tcp_hdr(skb);
 313         const unsigned char *ptr;
 314         int length;
 315
 316         /* initialize option status */
 317         mp_opt->mp_capable = 0;
 318         mp_opt->mp_join = 0;
 319         mp_opt->add_addr = 0;
 320         mp_opt->ahmac = 0;
 321         mp_opt->fastclose = 0;
 322         mp_opt->port = 0;
 323         mp_opt->rm_addr = 0;
 324         mp_opt->dss = 0;
 325         mp_opt->mp_prio = 0;
 326
 327         length = (th->doff * 4) - sizeof(struct tcphdr);
 328         ptr = (const unsigned char *)(th + 1);
 329
 330         while (length > 0) {
 331                 int opcode = *ptr++;
 332                 int opsize;
 333
 334                 switch (opcode) {
 335                 case TCPOPT_EOL:
 336                         return;
 337                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 338                         length--;
 339                         continue;
 340                 default:
 341                         opsize = *ptr++;
 342                         if (opsize < 2) /* "silly options" */
 343                                 return;
 344                         if (opsize > length)
 345                                 return; /* don't parse partial options */
 346                         if (opcode == TCPOPT_MPTCP)
 347                                 mptcp_parse_option(skb, ptr, opsize, mp_opt);
 348                         ptr += opsize - 2;
 349                         length -= opsize;
 350                 }
 351         }
 352 }
 353
 354 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 355                        unsigned int *size, struct mptcp_out_options *opts)
 356 {
 357         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 358
 359         /* we will use snd_isn to detect first pkt [re]transmission
 360          * in mptcp_established_options_mp()
 361          */
 362         subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
 363         if (subflow->request_mptcp) {
 364                 opts->suboptions = OPTION_MPTCP_MPC_SYN;
 365                 *size = TCPOLEN_MPTCP_MPC_SYN;
 366                 return true;
 367         } else if (subflow->request_join) {
 368                 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
 369                          subflow->local_nonce);
 370                 opts->suboptions = OPTION_MPTCP_MPJ_SYN;
 371                 opts->join_id = subflow->local_id;
 372                 opts->token = subflow->remote_token;
 373                 opts->nonce = subflow->local_nonce;
 374                 opts->backup = subflow->request_bkup;
 375                 *size = TCPOLEN_MPTCP_MPJ_SYN;
 376                 return true;
 377         }
 378         return false;
 379 }
 380
 381 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
 382  * TCP can't schedule delack timer before the subflow is fully established.
 383  * MPTCP uses the delack timer to do 3rd ack retransmissions
 384  */
 385 static void schedule_3rdack_retransmission(struct sock *sk)
 386 {
 387         struct inet_connection_sock *icsk = inet_csk(sk);
 388         struct tcp_sock *tp = tcp_sk(sk);
 389         unsigned long timeout;
 390
 391         /* reschedule with a timeout above RTT, as we must look only for drop */
 392         if (tp->srtt_us)
 393                 timeout = tp->srtt_us << 1;
 394         else
 395                 timeout = TCP_TIMEOUT_INIT;
 396
 397         WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
 398         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 399         icsk->icsk_ack.timeout = timeout;
 400         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 401 }
 402
 403 static void clear_3rdack_retransmission(struct sock *sk)
 404 {
 405         struct inet_connection_sock *icsk = inet_csk(sk);
 406
 407         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 408         icsk->icsk_ack.timeout = 0;
 409         icsk->icsk_ack.ato = 0;
 410         icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
 411 }
 412
 413 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 414                                          unsigned int *size,
 415                                          unsigned int remaining,
 416                                          struct mptcp_out_options *opts)
 417 {
 418         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 419         struct mptcp_ext *mpext;
 420         unsigned int data_len;
 421
 422         /* When skb is not available, we better over-estimate the emitted
 423          * options len. A full DSS option (28 bytes) is longer than
 424          * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
 425          * tell the caller to defer the estimate to
 426          * mptcp_established_options_dss(), which will reserve enough space.
 427          */
 428         if (!skb)
 429                 return false;
 430
 431         /* MPC/MPJ needed only on 3rd ack packet */
 432         if (subflow->fully_established ||
 433             subflow->snd_isn != TCP_SKB_CB(skb)->seq)
 434                 return false;
 435
 436         if (subflow->mp_capable) {
 437                 mpext = mptcp_get_ext(skb);
 438                 data_len = mpext ? mpext->data_len : 0;
 439
 440                 /* we will check ext_copy.data_len in mptcp_write_options() to
 441                  * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
 442                  * TCPOLEN_MPTCP_MPC_ACK
 443                  */
 444                 opts->ext_copy.data_len = data_len;
 445                 opts->suboptions = OPTION_MPTCP_MPC_ACK;
 446                 opts->sndr_key = subflow->local_key;
 447                 opts->rcvr_key = subflow->remote_key;
 448
 449                 /* Section 3.1.
 450                  * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
 451                  * packets that start the first subflow of an MPTCP connection,
 452                  * as well as the first packet that carries data
 453                  */
 454                 if (data_len > 0)
 455                         *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
 456                 else
 457                         *size = TCPOLEN_MPTCP_MPC_ACK;
 458
 459                 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
 460                          subflow, subflow->local_key, subflow->remote_key,
 461                          data_len);
 462
 463                 return true;
 464         } else if (subflow->mp_join) {
 465                 opts->suboptions = OPTION_MPTCP_MPJ_ACK;
 466                 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
 467                 *size = TCPOLEN_MPTCP_MPJ_ACK;
 468                 pr_debug("subflow=%p", subflow);
 469
 470                 schedule_3rdack_retransmission(sk);
 471                 return true;
 472         }
 473         return false;
 474 }
 475
 476 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
 477                                  struct sk_buff *skb, struct mptcp_ext *ext)
 478 {
 479         /* The write_seq value has already been incremented, so the actual
 480          * sequence number for the DATA_FIN is one less.
 481          */
 482         u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
 483
 484         if (!ext->use_map || !skb->len) {
 485                 /* RFC6824 requires a DSS mapping with specific values
 486                  * if DATA_FIN is set but no data payload is mapped
 487                  */
 488                 ext->data_fin = 1;
 489                 ext->use_map = 1;
 490                 ext->dsn64 = 1;
 491                 ext->data_seq = data_fin_tx_seq;
 492                 ext->subflow_seq = 0;
 493                 ext->data_len = 1;
 494         } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
 495                 /* If there's an existing DSS mapping and it is the
 496                  * final mapping, DATA_FIN consumes 1 additional byte of
 497                  * mapping space.
 498                  */
 499                 ext->data_fin = 1;
 500                 ext->data_len++;
 501         }
 502 }
 503
 504 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 505                                           unsigned int *size,
 506                                           unsigned int remaining,
 507                                           struct mptcp_out_options *opts)
 508 {
 509         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 510         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 511         u64 snd_data_fin_enable, ack_seq;
 512         unsigned int dss_size = 0;
 513         struct mptcp_ext *mpext;
 514         unsigned int ack_size;
 515         bool ret = false;
 516
 517         mpext = skb ? mptcp_get_ext(skb) : NULL;
 518         snd_data_fin_enable = mptcp_data_fin_enabled(msk);
 519
 520         if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
 521                 unsigned int map_size;
 522
 523                 map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
 524
 525                 remaining -= map_size;
 526                 dss_size = map_size;
 527                 if (mpext)
 528                         opts->ext_copy = *mpext;
 529
 530                 if (skb && snd_data_fin_enable)
 531                         mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
 532                 ret = true;
 533         }
 534
 535         /* passive sockets msk will set the 'can_ack' after accept(), even
 536          * if the first subflow may have the already the remote key handy
 537          */
 538         opts->ext_copy.use_ack = 0;
 539         if (!READ_ONCE(msk->can_ack)) {
 540                 *size = ALIGN(dss_size, 4);
 541                 return ret;
 542         }
 543
 544         ack_seq = READ_ONCE(msk->ack_seq);
 545         if (READ_ONCE(msk->use_64bit_ack)) {
 546                 ack_size = TCPOLEN_MPTCP_DSS_ACK64;
 547                 opts->ext_copy.data_ack = ack_seq;
 548                 opts->ext_copy.ack64 = 1;
 549         } else {
 550                 ack_size = TCPOLEN_MPTCP_DSS_ACK32;
 551                 opts->ext_copy.data_ack32 = (uint32_t)ack_seq;
 552                 opts->ext_copy.ack64 = 0;
 553         }
 554         opts->ext_copy.use_ack = 1;
 555         WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
 556
 557         /* Add kind/length/subtype/flag overhead if mapping is not populated */
 558         if (dss_size == 0)
 559                 ack_size += TCPOLEN_MPTCP_DSS_BASE;
 560
 561         dss_size += ack_size;
 562
 563         *size = ALIGN(dss_size, 4);
 564         return true;
 565 }
 566
 567 static u64 add_addr_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 568                                   struct in_addr *addr)
 569 {
 570         u8 hmac[SHA256_DIGEST_SIZE];
 571         u8 msg[7];
 572
 573         msg[0] = addr_id;
 574         memcpy(&msg[1], &addr->s_addr, 4);
 575         msg[5] = 0;
 576         msg[6] = 0;
 577
 578         mptcp_crypto_hmac_sha(key1, key2, msg, 7, hmac);
 579
 580         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 581 }
 582
 583 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 584 static u64 add_addr6_generate_hmac(u64 key1, u64 key2, u8 addr_id,
 585                                    struct in6_addr *addr)
 586 {
 587         u8 hmac[SHA256_DIGEST_SIZE];
 588         u8 msg[19];
 589
 590         msg[0] = addr_id;
 591         memcpy(&msg[1], &addr->s6_addr, 16);
 592         msg[17] = 0;
 593         msg[18] = 0;
 594
 595         mptcp_crypto_hmac_sha(key1, key2, msg, 19, hmac);
 596
 597         return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 598 }
 599 #endif
 600
 601 static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb,
 602                                                unsigned int *size,
 603                                                unsigned int remaining,
 604                                                struct mptcp_out_options *opts)
 605 {
 606         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 607         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 608         bool drop_other_suboptions = false;
 609         unsigned int opt_size = *size;
 610         struct mptcp_addr_info saddr;
 611         bool echo;
 612         bool port;
 613         int len;
 614
 615         if ((mptcp_pm_should_add_signal_ipv6(msk) ||
 616              mptcp_pm_should_add_signal_port(msk)) &&
 617             skb && skb_is_tcp_pure_ack(skb)) {
 618                 pr_debug("drop other suboptions");
 619                 opts->suboptions = 0;
 620                 opts->ext_copy.use_ack = 0;
 621                 opts->ext_copy.use_map = 0;
 622                 remaining += opt_size;
 623                 drop_other_suboptions = true;
 624         }
 625
 626         if (!mptcp_pm_should_add_signal(msk) ||
 627             !(mptcp_pm_add_addr_signal(msk, remaining, &saddr, &echo, &port)))
 628                 return false;
 629
 630         len = mptcp_add_addr_len(saddr.family, echo, port);
 631         if (remaining < len)
 632                 return false;
 633
 634         *size = len;
 635         if (drop_other_suboptions)
 636                 *size -= opt_size;
 637         opts->addr_id = saddr.id;
 638         if (port)
 639                 opts->port = ntohs(saddr.port);
 640         if (saddr.family == AF_INET) {
 641                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
 642                 opts->addr = saddr.addr;
 643                 if (!echo) {
 644                         opts->ahmac = add_addr_generate_hmac(msk->local_key,
 645                                                              msk->remote_key,
 646                                                              opts->addr_id,
 647                                                              &opts->addr);
 648                 }
 649         }
 650 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 651         else if (saddr.family == AF_INET6) {
 652                 opts->suboptions |= OPTION_MPTCP_ADD_ADDR6;
 653                 opts->addr6 = saddr.addr6;
 654                 if (!echo) {
 655                         opts->ahmac = add_addr6_generate_hmac(msk->local_key,
 656                                                               msk->remote_key,
 657                                                               opts->addr_id,
 658                                                               &opts->addr6);
 659                 }
 660         }
 661 #endif
 662         pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
 663                  opts->addr_id, opts->ahmac, echo, opts->port);
 664
 665         return true;
 666 }
 667
 668 static bool mptcp_established_options_rm_addr(struct sock *sk,
 669                                               unsigned int *size,
 670                                               unsigned int remaining,
 671                                               struct mptcp_out_options *opts)
 672 {
 673         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 674         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 675         u8 rm_id;
 676
 677         if (!mptcp_pm_should_rm_signal(msk) ||
 678             !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_id)))
 679                 return false;
 680
 681         if (remaining < TCPOLEN_MPTCP_RM_ADDR_BASE)
 682                 return false;
 683
 684         *size = TCPOLEN_MPTCP_RM_ADDR_BASE;
 685         opts->suboptions |= OPTION_MPTCP_RM_ADDR;
 686         opts->rm_id = rm_id;
 687
 688         pr_debug("rm_id=%d", opts->rm_id);
 689
 690         return true;
 691 }
 692
 693 static bool mptcp_established_options_mp_prio(struct sock *sk,
 694                                               unsigned int *size,
 695                                               unsigned int remaining,
 696                                               struct mptcp_out_options *opts)
 697 {
 698         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 699
 700         if (!subflow->send_mp_prio)
 701                 return false;
 702
 703         /* account for the trailing 'nop' option */
 704         if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN)
 705                 return false;
 706
 707         *size = TCPOLEN_MPTCP_PRIO_ALIGN;
 708         opts->suboptions |= OPTION_MPTCP_PRIO;
 709         opts->backup = subflow->request_bkup;
 710
 711         pr_debug("prio=%d", opts->backup);
 712
 713         return true;
 714 }
 715
 716 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 717                                unsigned int *size, unsigned int remaining,
 718                                struct mptcp_out_options *opts)
 719 {
 720         unsigned int opt_size = 0;
 721         bool ret = false;
 722
 723         opts->suboptions = 0;
 724
 725         if (unlikely(mptcp_check_fallback(sk)))
 726                 return false;
 727
 728         /* prevent adding of any MPTCP related options on reset packet
 729          * until we support MP_TCPRST/MP_FASTCLOSE
 730          */
 731         if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
 732                 return false;
 733
 734         if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
 735                 ret = true;
 736         else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
 737                                                opts))
 738                 ret = true;
 739
 740         /* we reserved enough space for the above options, and exceeding the
 741          * TCP option space would be fatal
 742          */
 743         if (WARN_ON_ONCE(opt_size > remaining))
 744                 return false;
 745
 746         *size += opt_size;
 747         remaining -= opt_size;
 748         if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
 749                 *size += opt_size;
 750                 remaining -= opt_size;
 751                 ret = true;
 752         } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
 753                 *size += opt_size;
 754                 remaining -= opt_size;
 755                 ret = true;
 756         }
 757
 758         if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) {
 759                 *size += opt_size;
 760                 remaining -= opt_size;
 761                 ret = true;
 762         }
 763
 764         return ret;
 765 }
 766
 767 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 768                           struct mptcp_out_options *opts)
 769 {
 770         struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 771
 772         if (subflow_req->mp_capable) {
 773                 opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
 774                 opts->sndr_key = subflow_req->local_key;
 775                 *size = TCPOLEN_MPTCP_MPC_SYNACK;
 776                 pr_debug("subflow_req=%p, local_key=%llu",
 777                          subflow_req, subflow_req->local_key);
 778                 return true;
 779         } else if (subflow_req->mp_join) {
 780                 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
 781                 opts->backup = subflow_req->backup;
 782                 opts->join_id = subflow_req->local_id;
 783                 opts->thmac = subflow_req->thmac;
 784                 opts->nonce = subflow_req->local_nonce;
 785                 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
 786                          subflow_req, opts->backup, opts->join_id,
 787                          opts->thmac, opts->nonce);
 788                 *size = TCPOLEN_MPTCP_MPJ_SYNACK;
 789                 return true;
 790         }
 791         return false;
 792 }
 793
 794 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
 795                                     struct mptcp_subflow_context *subflow,
 796                                     struct sk_buff *skb,
 797                                     struct mptcp_options_received *mp_opt)
 798 {
 799         /* here we can process OoO, in-window pkts, only in-sequence 4th ack
 800          * will make the subflow fully established
 801          */
 802         if (likely(subflow->fully_established)) {
 803                 /* on passive sockets, check for 3rd ack retransmission
 804                  * note that msk is always set by subflow_syn_recv_sock()
 805                  * for mp_join subflows
 806                  */
 807                 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
 808                     TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
 809                     subflow->mp_join && mp_opt->mp_join &&
 810                     READ_ONCE(msk->pm.server_side))
 811                         tcp_send_ack(ssk);
 812                 goto fully_established;
 813         }
 814
 815         /* we must process OoO packets before the first subflow is fully
 816          * established. OoO packets are instead a protocol violation
 817          * for MP_JOIN subflows as the peer must not send any data
 818          * before receiving the forth ack - cfr. RFC 8684 section 3.2.
 819          */
 820         if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
 821                 if (subflow->mp_join)
 822                         goto reset;
 823                 return subflow->mp_capable;
 824         }
 825
 826         if (mp_opt->dss && mp_opt->use_ack) {
 827                 /* subflows are fully established as soon as we get any
 828                  * additional ack.
 829                  */
 830                 subflow->fully_established = 1;
 831                 WRITE_ONCE(msk->fully_established, true);
 832                 goto fully_established;
 833         }
 834
 835         if (mp_opt->add_addr) {
 836                 WRITE_ONCE(msk->fully_established, true);
 837                 return true;
 838         }
 839
 840         /* If the first established packet does not contain MP_CAPABLE + data
 841          * then fallback to TCP. Fallback scenarios requires a reset for
 842          * MP_JOIN subflows.
 843          */
 844         if (!mp_opt->mp_capable) {
 845                 if (subflow->mp_join)
 846                         goto reset;
 847                 subflow->mp_capable = 0;
 848                 pr_fallback(msk);
 849                 __mptcp_do_fallback(msk);
 850                 return false;
 851         }
 852
 853         if (unlikely(!READ_ONCE(msk->pm.server_side)))
 854                 pr_warn_once("bogus mpc option on established client sk");
 855         mptcp_subflow_fully_established(subflow, mp_opt);
 856
 857 fully_established:
 858         /* if the subflow is not already linked into the conn_list, we can't
 859          * notify the PM: this subflow is still on the listener queue
 860          * and the PM possibly acquiring the subflow lock could race with
 861          * the listener close
 862          */
 863         if (likely(subflow->pm_notified) || list_empty(&subflow->node))
 864                 return true;
 865
 866         subflow->pm_notified = 1;
 867         if (subflow->mp_join) {
 868                 clear_3rdack_retransmission(ssk);
 869                 mptcp_pm_subflow_established(msk, subflow);
 870         } else {
 871                 mptcp_pm_fully_established(msk, ssk, GFP_ATOMIC);
 872         }
 873         return true;
 874
 875 reset:
 876         mptcp_subflow_reset(ssk);
 877         return false;
 878 }
 879
 880 static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
 881 {
 882         u32 old_ack32, cur_ack32;
 883
 884         if (use_64bit)
 885                 return cur_ack;
 886
 887         old_ack32 = (u32)old_ack;
 888         cur_ack32 = (u32)cur_ack;
 889         cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
 890         if (unlikely(before(cur_ack32, old_ack32)))
 891                 return cur_ack + (1LL << 32);
 892         return cur_ack;
 893 }
 894
 895 static void ack_update_msk(struct mptcp_sock *msk,
 896                            struct sock *ssk,
 897                            struct mptcp_options_received *mp_opt)
 898 {
 899         u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt);
 900         struct sock *sk = (struct sock *)msk;
 901         u64 old_snd_una;
 902
 903         mptcp_data_lock(sk);
 904
 905         /* avoid ack expansion on update conflict, to reduce the risk of
 906          * wrongly expanding to a future ack sequence number, which is way
 907          * more dangerous than missing an ack
 908          */
 909         old_snd_una = msk->snd_una;
 910         new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
 911
 912         /* ACK for data not even sent yet? Ignore. */
 913         if (after64(new_snd_una, snd_nxt))
 914                 new_snd_una = old_snd_una;
 915
 916         new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
 917
 918         if (after64(new_wnd_end, msk->wnd_end))
 919                 msk->wnd_end = new_wnd_end;
 920
 921         /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
 922         if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)))
 923                 __mptcp_check_push(sk, ssk);
 924
 925         if (after64(new_snd_una, old_snd_una)) {
 926                 msk->snd_una = new_snd_una;
 927                 __mptcp_data_acked(sk);
 928         }
 929         mptcp_data_unlock(sk);
 930 }
 931
 932 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
 933 {
 934         /* Skip if DATA_FIN was already received.
 935          * If updating simultaneously with the recvmsg loop, values
 936          * should match. If they mismatch, the peer is misbehaving and
 937          * we will prefer the most recent information.
 938          */
 939         if (READ_ONCE(msk->rcv_data_fin) || !READ_ONCE(msk->first))
 940                 return false;
 941
 942         WRITE_ONCE(msk->rcv_data_fin_seq,
 943                    expand_ack(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
 944         WRITE_ONCE(msk->rcv_data_fin, 1);
 945
 946         return true;
 947 }
 948
 949 static bool add_addr_hmac_valid(struct mptcp_sock *msk,
 950                                 struct mptcp_options_received *mp_opt)
 951 {
 952         u64 hmac = 0;
 953
 954         if (mp_opt->echo)
 955                 return true;
 956
 957         if (mp_opt->family == MPTCP_ADDR_IPVERSION_4)
 958                 hmac = add_addr_generate_hmac(msk->remote_key,
 959                                               msk->local_key,
 960                                               mp_opt->addr_id, &mp_opt->addr);
 961 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 962         else
 963                 hmac = add_addr6_generate_hmac(msk->remote_key,
 964                                                msk->local_key,
 965                                                mp_opt->addr_id, &mp_opt->addr6);
 966 #endif
 967
 968         pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
 969                  msk, (unsigned long long)hmac,
 970                  (unsigned long long)mp_opt->ahmac);
 971
 972         return hmac == mp_opt->ahmac;
 973 }
 974
 975 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 976 {
 977         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 978         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 979         struct mptcp_options_received mp_opt;
 980         struct mptcp_ext *mpext;
 981
 982         if (__mptcp_check_fallback(msk)) {
 983                 /* Keep it simple and unconditionally trigger send data cleanup and
 984                  * pending queue spooling. We will need to acquire the data lock
 985                  * for more accurate checks, and once the lock is acquired, such
 986                  * helpers are cheap.
 987                  */
 988                 mptcp_data_lock(subflow->conn);
 989                 if (sk_stream_memory_free(sk))
 990                         __mptcp_check_push(subflow->conn, sk);
 991                 __mptcp_data_acked(subflow->conn);
 992                 mptcp_data_unlock(subflow->conn);
 993                 return;
 994         }
 995
 996         mptcp_get_options(skb, &mp_opt);
 997         if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
 998                 return;
 999
1000         if (mp_opt.fastclose &&
1001             msk->local_key == mp_opt.rcvr_key) {
1002                 WRITE_ONCE(msk->rcv_fastclose, true);
1003                 mptcp_schedule_work((struct sock *)msk);
1004         }
1005
1006         if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
1007                 struct mptcp_addr_info addr;
1008
1009                 addr.port = htons(mp_opt.port);
1010                 addr.id = mp_opt.addr_id;
1011                 if (mp_opt.family == MPTCP_ADDR_IPVERSION_4) {
1012                         addr.family = AF_INET;
1013                         addr.addr = mp_opt.addr;
1014                 }
1015 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1016                 else if (mp_opt.family == MPTCP_ADDR_IPVERSION_6) {
1017                         addr.family = AF_INET6;
1018                         addr.addr6 = mp_opt.addr6;
1019                 }
1020 #endif
1021                 if (!mp_opt.echo) {
1022                         mptcp_pm_add_addr_received(msk, &addr);
1023                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
1024                 } else {
1025                         mptcp_pm_del_add_timer(msk, &addr);
1026                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
1027                 }
1028
1029                 if (mp_opt.port)
1030                         MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD);
1031
1032                 mp_opt.add_addr = 0;
1033         }
1034
1035         if (mp_opt.rm_addr) {
1036                 mptcp_pm_rm_addr_received(msk, mp_opt.rm_id);
1037                 mp_opt.rm_addr = 0;
1038         }
1039
1040         if (mp_opt.mp_prio) {
1041                 mptcp_pm_mp_prio_received(sk, mp_opt.backup);
1042                 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX);
1043                 mp_opt.mp_prio = 0;
1044         }
1045
1046         if (!mp_opt.dss)
1047                 return;
1048
1049         /* we can't wait for recvmsg() to update the ack_seq, otherwise
1050          * monodirectional flows will stuck
1051          */
1052         if (mp_opt.use_ack)
1053                 ack_update_msk(msk, sk, &mp_opt);
1054
1055         /* Zero-data-length packets are dropped by the caller and not
1056          * propagated to the MPTCP layer, so the skb extension does not
1057          * need to be allocated or populated. DATA_FIN information, if
1058          * present, needs to be updated here before the skb is freed.
1059          */
1060         if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
1061                 if (mp_opt.data_fin && mp_opt.data_len == 1 &&
1062                     mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
1063                     schedule_work(&msk->work))
1064                         sock_hold(subflow->conn);
1065
1066                 return;
1067         }
1068
1069         mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
1070         if (!mpext)
1071                 return;
1072
1073         memset(mpext, 0, sizeof(*mpext));
1074
1075         if (mp_opt.use_map) {
1076                 if (mp_opt.mpc_map) {
1077                         /* this is an MP_CAPABLE carrying MPTCP data
1078                          * we know this map the first chunk of data
1079                          */
1080                         mptcp_crypto_key_sha(subflow->remote_key, NULL,
1081                                              &mpext->data_seq);
1082                         mpext->data_seq++;
1083                         mpext->subflow_seq = 1;
1084                         mpext->dsn64 = 1;
1085                         mpext->mpc_map = 1;
1086                         mpext->data_fin = 0;
1087                 } else {
1088                         mpext->data_seq = mp_opt.data_seq;
1089                         mpext->subflow_seq = mp_opt.subflow_seq;
1090                         mpext->dsn64 = mp_opt.dsn64;
1091                         mpext->data_fin = mp_opt.data_fin;
1092                 }
1093                 mpext->data_len = mp_opt.data_len;
1094                 mpext->use_map = 1;
1095         }
1096 }
1097
1098 static void mptcp_set_rwin(const struct tcp_sock *tp)
1099 {
1100         const struct sock *ssk = (const struct sock *)tp;
1101         const struct mptcp_subflow_context *subflow;
1102         struct mptcp_sock *msk;
1103         u64 ack_seq;
1104
1105         subflow = mptcp_subflow_ctx(ssk);
1106         msk = mptcp_sk(subflow->conn);
1107
1108         ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd;
1109
1110         if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent)))
1111                 WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
1112 }
1113
1114 void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
1115                          struct mptcp_out_options *opts)
1116 {
1117         if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
1118              OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
1119                 u8 len;
1120
1121                 if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
1122                         len = TCPOLEN_MPTCP_MPC_SYN;
1123                 else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
1124                         len = TCPOLEN_MPTCP_MPC_SYNACK;
1125                 else if (opts->ext_copy.data_len)
1126                         len = TCPOLEN_MPTCP_MPC_ACK_DATA;
1127                 else
1128                         len = TCPOLEN_MPTCP_MPC_ACK;
1129
1130                 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
1131                                       MPTCP_SUPPORTED_VERSION,
1132                                       MPTCP_CAP_HMAC_SHA256);
1133
1134                 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
1135                     opts->suboptions))
1136                         goto mp_capable_done;
1137
1138                 put_unaligned_be64(opts->sndr_key, ptr);
1139                 ptr += 2;
1140                 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1141                         goto mp_capable_done;
1142
1143                 put_unaligned_be64(opts->rcvr_key, ptr);
1144                 ptr += 2;
1145                 if (!opts->ext_copy.data_len)
1146                         goto mp_capable_done;
1147
1148                 put_unaligned_be32(opts->ext_copy.data_len << 16 |
1149                                    TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1150                 ptr += 1;
1151         }
1152
1153 mp_capable_done:
1154         if ((OPTION_MPTCP_ADD_ADDR
1155 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1156              | OPTION_MPTCP_ADD_ADDR6
1157 #endif
1158             ) & opts->suboptions) {
1159                 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
1160                 u8 echo = MPTCP_ADDR_ECHO;
1161
1162 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1163                 if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions)
1164                         len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
1165 #endif
1166
1167                 if (opts->port)
1168                         len += TCPOLEN_MPTCP_PORT_LEN;
1169
1170                 if (opts->ahmac) {
1171                         len += sizeof(opts->ahmac);
1172                         echo = 0;
1173                 }
1174
1175                 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1176                                       len, echo, opts->addr_id);
1177                 if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
1178                         memcpy((u8 *)ptr, (u8 *)&opts->addr.s_addr, 4);
1179                         ptr += 1;
1180                 }
1181 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1182                 else if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions) {
1183                         memcpy((u8 *)ptr, opts->addr6.s6_addr, 16);
1184                         ptr += 4;
1185                 }
1186 #endif
1187
1188                 if (!opts->port) {
1189                         if (opts->ahmac) {
1190                                 put_unaligned_be64(opts->ahmac, ptr);
1191                                 ptr += 2;
1192                         }
1193                 } else {
1194                         if (opts->ahmac) {
1195                                 u8 *bptr = (u8 *)ptr;
1196
1197                                 put_unaligned_be16(opts->port, bptr);
1198                                 bptr += 2;
1199                                 put_unaligned_be64(opts->ahmac, bptr);
1200                                 bptr += 8;
1201                                 put_unaligned_be16(TCPOPT_NOP << 8 |
1202                                                    TCPOPT_NOP, bptr);
1203
1204                                 ptr += 3;
1205                         } else {
1206                                 put_unaligned_be32(opts->port << 16 |
1207                                                    TCPOPT_NOP << 8 |
1208                                                    TCPOPT_NOP, ptr);
1209                                 ptr += 1;
1210                         }
1211                 }
1212         }
1213
1214         if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1215                 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1216                                       TCPOLEN_MPTCP_RM_ADDR_BASE,
1217                                       0, opts->rm_id);
1218         }
1219
1220         if (OPTION_MPTCP_PRIO & opts->suboptions) {
1221                 const struct sock *ssk = (const struct sock *)tp;
1222                 struct mptcp_subflow_context *subflow;
1223
1224                 subflow = mptcp_subflow_ctx(ssk);
1225                 subflow->send_mp_prio = 0;
1226
1227                 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
1228                                       TCPOLEN_MPTCP_PRIO,
1229                                       opts->backup, TCPOPT_NOP);
1230         }
1231
1232         if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1233                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1234                                       TCPOLEN_MPTCP_MPJ_SYN,
1235                                       opts->backup, opts->join_id);
1236                 put_unaligned_be32(opts->token, ptr);
1237                 ptr += 1;
1238                 put_unaligned_be32(opts->nonce, ptr);
1239                 ptr += 1;
1240         }
1241
1242         if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1243                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1244                                       TCPOLEN_MPTCP_MPJ_SYNACK,
1245                                       opts->backup, opts->join_id);
1246                 put_unaligned_be64(opts->thmac, ptr);
1247                 ptr += 2;
1248                 put_unaligned_be32(opts->nonce, ptr);
1249                 ptr += 1;
1250         }
1251
1252         if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1253                 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1254                                       TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1255                 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1256                 ptr += 5;
1257         }
1258
1259         if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
1260                 struct mptcp_ext *mpext = &opts->ext_copy;
1261                 u8 len = TCPOLEN_MPTCP_DSS_BASE;
1262                 u8 flags = 0;
1263
1264                 if (mpext->use_ack) {
1265                         flags = MPTCP_DSS_HAS_ACK;
1266                         if (mpext->ack64) {
1267                                 len += TCPOLEN_MPTCP_DSS_ACK64;
1268                                 flags |= MPTCP_DSS_ACK64;
1269                         } else {
1270                                 len += TCPOLEN_MPTCP_DSS_ACK32;
1271                         }
1272                 }
1273
1274                 if (mpext->use_map) {
1275                         len += TCPOLEN_MPTCP_DSS_MAP64;
1276
1277                         /* Use only 64-bit mapping flags for now, add
1278                          * support for optional 32-bit mappings later.
1279                          */
1280                         flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1281                         if (mpext->data_fin)
1282                                 flags |= MPTCP_DSS_DATA_FIN;
1283                 }
1284
1285                 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
1286
1287                 if (mpext->use_ack) {
1288                         if (mpext->ack64) {
1289                                 put_unaligned_be64(mpext->data_ack, ptr);
1290                                 ptr += 2;
1291                         } else {
1292                                 put_unaligned_be32(mpext->data_ack32, ptr);
1293                                 ptr += 1;
1294                         }
1295                 }
1296
1297                 if (mpext->use_map) {
1298                         put_unaligned_be64(mpext->data_seq, ptr);
1299                         ptr += 2;
1300                         put_unaligned_be32(mpext->subflow_seq, ptr);
1301                         ptr += 1;
1302                         put_unaligned_be32(mpext->data_len << 16 |
1303                                            TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1304                 }
1305         }
1306
1307         if (tp)
1308                 mptcp_set_rwin(tp);
1309 }