net/netfilter/nf_conntrack_proto_dccp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * DCCP connection tracking protocol helper
   4  *
   5  * Copyright (c) 2005, 2006, 2008 Patrick McHardy <kaber@trash.net>
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/init.h>
   9 #include <linux/sysctl.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/dccp.h>
  13 #include <linux/slab.h>
  14
  15 #include <net/net_namespace.h>
  16 #include <net/netns/generic.h>
  17
  18 #include <linux/netfilter/nfnetlink_conntrack.h>
  19 #include <net/netfilter/nf_conntrack.h>
  20 #include <net/netfilter/nf_conntrack_l4proto.h>
  21 #include <net/netfilter/nf_conntrack_ecache.h>
  22 #include <net/netfilter/nf_conntrack_timeout.h>
  23 #include <net/netfilter/nf_log.h>
  24
  25 /* Timeouts are based on values from RFC4340:
  26  *
  27  * - REQUEST:
  28  *
  29  *   8.1.2. Client Request
  30  *
  31  *   A client MAY give up on its DCCP-Requests after some time
  32  *   (3 minutes, for example).
  33  *
  34  * - RESPOND:
  35  *
  36  *   8.1.3. Server Response
  37  *
  38  *   It MAY also leave the RESPOND state for CLOSED after a timeout of
  39  *   not less than 4MSL (8 minutes);
  40  *
  41  * - PARTOPEN:
  42  *
  43  *   8.1.5. Handshake Completion
  44  *
  45  *   If the client remains in PARTOPEN for more than 4MSL (8 minutes),
  46  *   it SHOULD reset the connection with Reset Code 2, "Aborted".
  47  *
  48  * - OPEN:
  49  *
  50  *   The DCCP timestamp overflows after 11.9 hours. If the connection
  51  *   stays idle this long the sequence number won't be recognized
  52  *   as valid anymore.
  53  *
  54  * - CLOSEREQ/CLOSING:
  55  *
  56  *   8.3. Termination
  57  *
  58  *   The retransmission timer should initially be set to go off in two
  59  *   round-trip times and should back off to not less than once every
  60  *   64 seconds ...
  61  *
  62  * - TIMEWAIT:
  63  *
  64  *   4.3. States
  65  *
  66  *   A server or client socket remains in this state for 2MSL (4 minutes)
  67  *   after the connection has been town down, ...
  68  */
  69
  70 #define DCCP_MSL (2 * 60 * HZ)
  71
  72 #ifdef CONFIG_NF_CONNTRACK_PROCFS
  73 static const char * const dccp_state_names[] = {
  74         [CT_DCCP_NONE]          = "NONE",
  75         [CT_DCCP_REQUEST]       = "REQUEST",
  76         [CT_DCCP_RESPOND]       = "RESPOND",
  77         [CT_DCCP_PARTOPEN]      = "PARTOPEN",
  78         [CT_DCCP_OPEN]          = "OPEN",
  79         [CT_DCCP_CLOSEREQ]      = "CLOSEREQ",
  80         [CT_DCCP_CLOSING]       = "CLOSING",
  81         [CT_DCCP_TIMEWAIT]      = "TIMEWAIT",
  82         [CT_DCCP_IGNORE]        = "IGNORE",
  83         [CT_DCCP_INVALID]       = "INVALID",
  84 };
  85 #endif
  86
  87 #define sNO     CT_DCCP_NONE
  88 #define sRQ     CT_DCCP_REQUEST
  89 #define sRS     CT_DCCP_RESPOND
  90 #define sPO     CT_DCCP_PARTOPEN
  91 #define sOP     CT_DCCP_OPEN
  92 #define sCR     CT_DCCP_CLOSEREQ
  93 #define sCG     CT_DCCP_CLOSING
  94 #define sTW     CT_DCCP_TIMEWAIT
  95 #define sIG     CT_DCCP_IGNORE
  96 #define sIV     CT_DCCP_INVALID
  97
  98 /*
  99  * DCCP state transition table
 100  *
 101  * The assumption is the same as for TCP tracking:
 102  *
 103  * We are the man in the middle. All the packets go through us but might
 104  * get lost in transit to the destination. It is assumed that the destination
 105  * can't receive segments we haven't seen.
 106  *
 107  * The following states exist:
 108  *
 109  * NONE:        Initial state, expecting Request
 110  * REQUEST:     Request seen, waiting for Response from server
 111  * RESPOND:     Response from server seen, waiting for Ack from client
 112  * PARTOPEN:    Ack after Response seen, waiting for packet other than Response,
 113  *              Reset or Sync from server
 114  * OPEN:        Packet other than Response, Reset or Sync seen
 115  * CLOSEREQ:    CloseReq from server seen, expecting Close from client
 116  * CLOSING:     Close seen, expecting Reset
 117  * TIMEWAIT:    Reset seen
 118  * IGNORE:      Not determinable whether packet is valid
 119  *
 120  * Some states exist only on one side of the connection: REQUEST, RESPOND,
 121  * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to
 122  * the one it was in before.
 123  *
 124  * Packets are marked as ignored (sIG) if we don't know if they're valid
 125  * (for example a reincarnation of a connection we didn't notice is dead
 126  * already) and the server may send back a connection closing Reset or a
 127  * Response. They're also used for Sync/SyncAck packets, which we don't
 128  * care about.
 129  */
 130 static const u_int8_t
 131 dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = {
 132         [CT_DCCP_ROLE_CLIENT] = {
 133                 [DCCP_PKT_REQUEST] = {
 134                 /*
 135                  * sNO -> sRQ           Regular Request
 136                  * sRQ -> sRQ           Retransmitted Request or reincarnation
 137                  * sRS -> sRS           Retransmitted Request (apparently Response
 138                  *                      got lost after we saw it) or reincarnation
 139                  * sPO -> sIG           Ignore, conntrack might be out of sync
 140                  * sOP -> sIG           Ignore, conntrack might be out of sync
 141                  * sCR -> sIG           Ignore, conntrack might be out of sync
 142                  * sCG -> sIG           Ignore, conntrack might be out of sync
 143                  * sTW -> sRQ           Reincarnation
 144                  *
 145                  *      sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */
 146                         sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ,
 147                 },
 148                 [DCCP_PKT_RESPONSE] = {
 149                 /*
 150                  * sNO -> sIV           Invalid
 151                  * sRQ -> sIG           Ignore, might be response to ignored Request
 152                  * sRS -> sIG           Ignore, might be response to ignored Request
 153                  * sPO -> sIG           Ignore, might be response to ignored Request
 154                  * sOP -> sIG           Ignore, might be response to ignored Request
 155                  * sCR -> sIG           Ignore, might be response to ignored Request
 156                  * sCG -> sIG           Ignore, might be response to ignored Request
 157                  * sTW -> sIV           Invalid, reincarnation in reverse direction
 158                  *                      goes through sRQ
 159                  *
 160                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 161                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV,
 162                 },
 163                 [DCCP_PKT_ACK] = {
 164                 /*
 165                  * sNO -> sIV           No connection
 166                  * sRQ -> sIV           No connection
 167                  * sRS -> sPO           Ack for Response, move to PARTOPEN (8.1.5.)
 168                  * sPO -> sPO           Retransmitted Ack for Response, remain in PARTOPEN
 169                  * sOP -> sOP           Regular ACK, remain in OPEN
 170                  * sCR -> sCR           Ack in CLOSEREQ MAY be processed (8.3.)
 171                  * sCG -> sCG           Ack in CLOSING MAY be processed (8.3.)
 172                  * sTW -> sIV
 173                  *
 174                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 175                         sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
 176                 },
 177                 [DCCP_PKT_DATA] = {
 178                 /*
 179                  * sNO -> sIV           No connection
 180                  * sRQ -> sIV           No connection
 181                  * sRS -> sIV           No connection
 182                  * sPO -> sIV           MUST use DataAck in PARTOPEN state (8.1.5.)
 183                  * sOP -> sOP           Regular Data packet
 184                  * sCR -> sCR           Data in CLOSEREQ MAY be processed (8.3.)
 185                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 186                  * sTW -> sIV
 187                  *
 188                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 189                         sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV,
 190                 },
 191                 [DCCP_PKT_DATAACK] = {
 192                 /*
 193                  * sNO -> sIV           No connection
 194                  * sRQ -> sIV           No connection
 195                  * sRS -> sPO           Ack for Response, move to PARTOPEN (8.1.5.)
 196                  * sPO -> sPO           Remain in PARTOPEN state
 197                  * sOP -> sOP           Regular DataAck packet in OPEN state
 198                  * sCR -> sCR           DataAck in CLOSEREQ MAY be processed (8.3.)
 199                  * sCG -> sCG           DataAck in CLOSING MAY be processed (8.3.)
 200                  * sTW -> sIV
 201                  *
 202                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 203                         sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
 204                 },
 205                 [DCCP_PKT_CLOSEREQ] = {
 206                 /*
 207                  * CLOSEREQ may only be sent by the server.
 208                  *
 209                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 210                         sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV
 211                 },
 212                 [DCCP_PKT_CLOSE] = {
 213                 /*
 214                  * sNO -> sIV           No connection
 215                  * sRQ -> sIV           No connection
 216                  * sRS -> sIV           No connection
 217                  * sPO -> sCG           Client-initiated close
 218                  * sOP -> sCG           Client-initiated close
 219                  * sCR -> sCG           Close in response to CloseReq (8.3.)
 220                  * sCG -> sCG           Retransmit
 221                  * sTW -> sIV           Late retransmit, already in TIME_WAIT
 222                  *
 223                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 224                         sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV
 225                 },
 226                 [DCCP_PKT_RESET] = {
 227                 /*
 228                  * sNO -> sIV           No connection
 229                  * sRQ -> sTW           Sync received or timeout, SHOULD send Reset (8.1.1.)
 230                  * sRS -> sTW           Response received without Request
 231                  * sPO -> sTW           Timeout, SHOULD send Reset (8.1.5.)
 232                  * sOP -> sTW           Connection reset
 233                  * sCR -> sTW           Connection reset
 234                  * sCG -> sTW           Connection reset
 235                  * sTW -> sIG           Ignore (don't refresh timer)
 236                  *
 237                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 238                         sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG
 239                 },
 240                 [DCCP_PKT_SYNC] = {
 241                 /*
 242                  * We currently ignore Sync packets
 243                  *
 244                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 245                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 246                 },
 247                 [DCCP_PKT_SYNCACK] = {
 248                 /*
 249                  * We currently ignore SyncAck packets
 250                  *
 251                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 252                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 253                 },
 254         },
 255         [CT_DCCP_ROLE_SERVER] = {
 256                 [DCCP_PKT_REQUEST] = {
 257                 /*
 258                  * sNO -> sIV           Invalid
 259                  * sRQ -> sIG           Ignore, conntrack might be out of sync
 260                  * sRS -> sIG           Ignore, conntrack might be out of sync
 261                  * sPO -> sIG           Ignore, conntrack might be out of sync
 262                  * sOP -> sIG           Ignore, conntrack might be out of sync
 263                  * sCR -> sIG           Ignore, conntrack might be out of sync
 264                  * sCG -> sIG           Ignore, conntrack might be out of sync
 265                  * sTW -> sRQ           Reincarnation, must reverse roles
 266                  *
 267                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 268                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ
 269                 },
 270                 [DCCP_PKT_RESPONSE] = {
 271                 /*
 272                  * sNO -> sIV           Response without Request
 273                  * sRQ -> sRS           Response to clients Request
 274                  * sRS -> sRS           Retransmitted Response (8.1.3. SHOULD NOT)
 275                  * sPO -> sIG           Response to an ignored Request or late retransmit
 276                  * sOP -> sIG           Ignore, might be response to ignored Request
 277                  * sCR -> sIG           Ignore, might be response to ignored Request
 278                  * sCG -> sIG           Ignore, might be response to ignored Request
 279                  * sTW -> sIV           Invalid, Request from client in sTW moves to sRQ
 280                  *
 281                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 282                         sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV
 283                 },
 284                 [DCCP_PKT_ACK] = {
 285                 /*
 286                  * sNO -> sIV           No connection
 287                  * sRQ -> sIV           No connection
 288                  * sRS -> sIV           No connection
 289                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 290                  * sOP -> sOP           Regular Ack in OPEN state
 291                  * sCR -> sIV           Waiting for Close from client
 292                  * sCG -> sCG           Ack in CLOSING MAY be processed (8.3.)
 293                  * sTW -> sIV
 294                  *
 295                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 296                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 297                 },
 298                 [DCCP_PKT_DATA] = {
 299                 /*
 300                  * sNO -> sIV           No connection
 301                  * sRQ -> sIV           No connection
 302                  * sRS -> sIV           No connection
 303                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 304                  * sOP -> sOP           Regular Data packet in OPEN state
 305                  * sCR -> sIV           Waiting for Close from client
 306                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 307                  * sTW -> sIV
 308                  *
 309                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 310                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 311                 },
 312                 [DCCP_PKT_DATAACK] = {
 313                 /*
 314                  * sNO -> sIV           No connection
 315                  * sRQ -> sIV           No connection
 316                  * sRS -> sIV           No connection
 317                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 318                  * sOP -> sOP           Regular DataAck in OPEN state
 319                  * sCR -> sIV           Waiting for Close from client
 320                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 321                  * sTW -> sIV
 322                  *
 323                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 324                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 325                 },
 326                 [DCCP_PKT_CLOSEREQ] = {
 327                 /*
 328                  * sNO -> sIV           No connection
 329                  * sRQ -> sIV           No connection
 330                  * sRS -> sIV           No connection
 331                  * sPO -> sOP -> sCR    Move directly to CLOSEREQ (8.1.5.)
 332                  * sOP -> sCR           CloseReq in OPEN state
 333                  * sCR -> sCR           Retransmit
 334                  * sCG -> sCR           Simultaneous close, client sends another Close
 335                  * sTW -> sIV           Already closed
 336                  *
 337                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 338                         sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV
 339                 },
 340                 [DCCP_PKT_CLOSE] = {
 341                 /*
 342                  * sNO -> sIV           No connection
 343                  * sRQ -> sIV           No connection
 344                  * sRS -> sIV           No connection
 345                  * sPO -> sOP -> sCG    Move direcly to CLOSING
 346                  * sOP -> sCG           Move to CLOSING
 347                  * sCR -> sIV           Close after CloseReq is invalid
 348                  * sCG -> sCG           Retransmit
 349                  * sTW -> sIV           Already closed
 350                  *
 351                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 352                         sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV
 353                 },
 354                 [DCCP_PKT_RESET] = {
 355                 /*
 356                  * sNO -> sIV           No connection
 357                  * sRQ -> sTW           Reset in response to Request
 358                  * sRS -> sTW           Timeout, SHOULD send Reset (8.1.3.)
 359                  * sPO -> sTW           Timeout, SHOULD send Reset (8.1.3.)
 360                  * sOP -> sTW
 361                  * sCR -> sTW
 362                  * sCG -> sTW
 363                  * sTW -> sIG           Ignore (don't refresh timer)
 364                  *
 365                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */
 366                         sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG
 367                 },
 368                 [DCCP_PKT_SYNC] = {
 369                 /*
 370                  * We currently ignore Sync packets
 371                  *
 372                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 373                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 374                 },
 375                 [DCCP_PKT_SYNCACK] = {
 376                 /*
 377                  * We currently ignore SyncAck packets
 378                  *
 379                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 380                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 381                 },
 382         },
 383 };
 384
 385 static noinline bool
 386 dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
 387          const struct dccp_hdr *dh,
 388          const struct nf_hook_state *hook_state)
 389 {
 390         struct net *net = nf_ct_net(ct);
 391         struct nf_dccp_net *dn;
 392         const char *msg;
 393         u_int8_t state;
 394
 395         state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
 396         switch (state) {
 397         default:
 398                 dn = nf_dccp_pernet(net);
 399                 if (dn->dccp_loose == 0) {
 400                         msg = "not picking up existing connection ";
 401                         goto out_invalid;
 402                 }
 403                 break;
 404         case CT_DCCP_REQUEST:
 405                 break;
 406         case CT_DCCP_INVALID:
 407                 msg = "invalid state transition ";
 408                 goto out_invalid;
 409         }
 410
 411         ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 412         ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 413         ct->proto.dccp.state = CT_DCCP_NONE;
 414         ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST;
 415         ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL;
 416         ct->proto.dccp.handshake_seq = 0;
 417         return true;
 418
 419 out_invalid:
 420         nf_ct_l4proto_log_invalid(skb, ct, hook_state, "%s", msg);
 421         return false;
 422 }
 423
 424 static u64 dccp_ack_seq(const struct dccp_hdr *dh)
 425 {
 426         const struct dccp_hdr_ack_bits *dhack;
 427
 428         dhack = (void *)dh + __dccp_basic_hdr_len(dh);
 429         return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
 430                      ntohl(dhack->dccph_ack_nr_low);
 431 }
 432
 433 static bool dccp_error(const struct dccp_hdr *dh,
 434                        struct sk_buff *skb, unsigned int dataoff,
 435                        const struct nf_hook_state *state)
 436 {
 437         static const unsigned long require_seq48 = 1 << DCCP_PKT_REQUEST |
 438                                                    1 << DCCP_PKT_RESPONSE |
 439                                                    1 << DCCP_PKT_CLOSEREQ |
 440                                                    1 << DCCP_PKT_CLOSE |
 441                                                    1 << DCCP_PKT_RESET |
 442                                                    1 << DCCP_PKT_SYNC |
 443                                                    1 << DCCP_PKT_SYNCACK;
 444         unsigned int dccp_len = skb->len - dataoff;
 445         unsigned int cscov;
 446         const char *msg;
 447         u8 type;
 448
 449         BUILD_BUG_ON(DCCP_PKT_INVALID >= BITS_PER_LONG);
 450
 451         if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
 452             dh->dccph_doff * 4 > dccp_len) {
 453                 msg = "nf_ct_dccp: truncated/malformed packet ";
 454                 goto out_invalid;
 455         }
 456
 457         cscov = dccp_len;
 458         if (dh->dccph_cscov) {
 459                 cscov = (dh->dccph_cscov - 1) * 4;
 460                 if (cscov > dccp_len) {
 461                         msg = "nf_ct_dccp: bad checksum coverage ";
 462                         goto out_invalid;
 463                 }
 464         }
 465
 466         if (state->hook == NF_INET_PRE_ROUTING &&
 467             state->net->ct.sysctl_checksum &&
 468             nf_checksum_partial(skb, state->hook, dataoff, cscov,
 469                                 IPPROTO_DCCP, state->pf)) {
 470                 msg = "nf_ct_dccp: bad checksum ";
 471                 goto out_invalid;
 472         }
 473
 474         type = dh->dccph_type;
 475         if (type >= DCCP_PKT_INVALID) {
 476                 msg = "nf_ct_dccp: reserved packet type ";
 477                 goto out_invalid;
 478         }
 479
 480         if (test_bit(type, &require_seq48) && !dh->dccph_x) {
 481                 msg = "nf_ct_dccp: type lacks 48bit sequence numbers";
 482                 goto out_invalid;
 483         }
 484
 485         return false;
 486 out_invalid:
 487         nf_l4proto_log_invalid(skb, state, IPPROTO_DCCP, "%s", msg);
 488         return true;
 489 }
 490
 491 struct nf_conntrack_dccp_buf {
 492         struct dccp_hdr dh;      /* generic header part */
 493         struct dccp_hdr_ext ext; /* optional depending dh->dccph_x */
 494         union {                  /* depends on header type */
 495                 struct dccp_hdr_ack_bits ack;
 496                 struct dccp_hdr_request req;
 497                 struct dccp_hdr_response response;
 498                 struct dccp_hdr_reset rst;
 499         } u;
 500 };
 501
 502 static struct dccp_hdr *
 503 dccp_header_pointer(const struct sk_buff *skb, int offset, const struct dccp_hdr *dh,
 504                     struct nf_conntrack_dccp_buf *buf)
 505 {
 506         unsigned int hdrlen = __dccp_hdr_len(dh);
 507
 508         if (hdrlen > sizeof(*buf))
 509                 return NULL;
 510
 511         return skb_header_pointer(skb, offset, hdrlen, buf);
 512 }
 513
 514 int nf_conntrack_dccp_packet(struct nf_conn *ct, struct sk_buff *skb,
 515                              unsigned int dataoff,
 516                              enum ip_conntrack_info ctinfo,
 517                              const struct nf_hook_state *state)
 518 {
 519         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 520         struct nf_conntrack_dccp_buf _dh;
 521         u_int8_t type, old_state, new_state;
 522         enum ct_dccp_roles role;
 523         unsigned int *timeouts;
 524         struct dccp_hdr *dh;
 525
 526         dh = skb_header_pointer(skb, dataoff, sizeof(*dh), &_dh.dh);
 527         if (!dh)
 528                 return NF_DROP;
 529
 530         if (dccp_error(dh, skb, dataoff, state))
 531                 return -NF_ACCEPT;
 532
 533         /* pull again, including possible 48 bit sequences and subtype header */
 534         dh = dccp_header_pointer(skb, dataoff, dh, &_dh);
 535         if (!dh)
 536                 return NF_DROP;
 537
 538         type = dh->dccph_type;
 539         if (!nf_ct_is_confirmed(ct) && !dccp_new(ct, skb, dh, state))
 540                 return -NF_ACCEPT;
 541
 542         if (type == DCCP_PKT_RESET &&
 543             !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 544                 /* Tear down connection immediately if only reply is a RESET */
 545                 nf_ct_kill_acct(ct, ctinfo, skb);
 546                 return NF_ACCEPT;
 547         }
 548
 549         spin_lock_bh(&ct->lock);
 550
 551         role = ct->proto.dccp.role[dir];
 552         old_state = ct->proto.dccp.state;
 553         new_state = dccp_state_table[role][type][old_state];
 554
 555         switch (new_state) {
 556         case CT_DCCP_REQUEST:
 557                 if (old_state == CT_DCCP_TIMEWAIT &&
 558                     role == CT_DCCP_ROLE_SERVER) {
 559                         /* Reincarnation in the reverse direction: reopen and
 560                          * reverse client/server roles. */
 561                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
 562                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
 563                 }
 564                 break;
 565         case CT_DCCP_RESPOND:
 566                 if (old_state == CT_DCCP_REQUEST)
 567                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 568                 break;
 569         case CT_DCCP_PARTOPEN:
 570                 if (old_state == CT_DCCP_RESPOND &&
 571                     type == DCCP_PKT_ACK &&
 572                     dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
 573                         set_bit(IPS_ASSURED_BIT, &ct->status);
 574                 break;
 575         case CT_DCCP_IGNORE:
 576                 /*
 577                  * Connection tracking might be out of sync, so we ignore
 578                  * packets that might establish a new connection and resync
 579                  * if the server responds with a valid Response.
 580                  */
 581                 if (ct->proto.dccp.last_dir == !dir &&
 582                     ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
 583                     type == DCCP_PKT_RESPONSE) {
 584                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
 585                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
 586                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 587                         new_state = CT_DCCP_RESPOND;
 588                         break;
 589                 }
 590                 ct->proto.dccp.last_dir = dir;
 591                 ct->proto.dccp.last_pkt = type;
 592
 593                 spin_unlock_bh(&ct->lock);
 594                 nf_ct_l4proto_log_invalid(skb, ct, state, "%s", "invalid packet");
 595                 return NF_ACCEPT;
 596         case CT_DCCP_INVALID:
 597                 spin_unlock_bh(&ct->lock);
 598                 nf_ct_l4proto_log_invalid(skb, ct, state, "%s", "invalid state transition");
 599                 return -NF_ACCEPT;
 600         }
 601
 602         ct->proto.dccp.last_dir = dir;
 603         ct->proto.dccp.last_pkt = type;
 604         ct->proto.dccp.state = new_state;
 605         spin_unlock_bh(&ct->lock);
 606
 607         if (new_state != old_state)
 608                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
 609
 610         timeouts = nf_ct_timeout_lookup(ct);
 611         if (!timeouts)
 612                 timeouts = nf_dccp_pernet(nf_ct_net(ct))->dccp_timeout;
 613         nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);
 614
 615         return NF_ACCEPT;
 616 }
 617
 618 static bool dccp_can_early_drop(const struct nf_conn *ct)
 619 {
 620         switch (ct->proto.dccp.state) {
 621         case CT_DCCP_CLOSEREQ:
 622         case CT_DCCP_CLOSING:
 623         case CT_DCCP_TIMEWAIT:
 624                 return true;
 625         default:
 626                 break;
 627         }
 628
 629         return false;
 630 }
 631
 632 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 633 static void dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 634 {
 635         seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
 636 }
 637 #endif
 638
 639 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 640 static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
 641                           struct nf_conn *ct, bool destroy)
 642 {
 643         struct nlattr *nest_parms;
 644
 645         spin_lock_bh(&ct->lock);
 646         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP);
 647         if (!nest_parms)
 648                 goto nla_put_failure;
 649         if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state))
 650                 goto nla_put_failure;
 651
 652         if (destroy)
 653                 goto skip_state;
 654
 655         if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_ROLE,
 656                        ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]) ||
 657             nla_put_be64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ,
 658                          cpu_to_be64(ct->proto.dccp.handshake_seq),
 659                          CTA_PROTOINFO_DCCP_PAD))
 660                 goto nla_put_failure;
 661 skip_state:
 662         nla_nest_end(skb, nest_parms);
 663         spin_unlock_bh(&ct->lock);
 664
 665         return 0;
 666
 667 nla_put_failure:
 668         spin_unlock_bh(&ct->lock);
 669         return -1;
 670 }
 671
 672 static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
 673         [CTA_PROTOINFO_DCCP_STATE]      = { .type = NLA_U8 },
 674         [CTA_PROTOINFO_DCCP_ROLE]       = { .type = NLA_U8 },
 675         [CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 },
 676         [CTA_PROTOINFO_DCCP_PAD]        = { .type = NLA_UNSPEC },
 677 };
 678
 679 #define DCCP_NLATTR_SIZE ( \
 680         NLA_ALIGN(NLA_HDRLEN + 1) + \
 681         NLA_ALIGN(NLA_HDRLEN + 1) + \
 682         NLA_ALIGN(NLA_HDRLEN + sizeof(u64)) + \
 683         NLA_ALIGN(NLA_HDRLEN + 0))
 684
 685 static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
 686 {
 687         struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
 688         struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
 689         int err;
 690
 691         if (!attr)
 692                 return 0;
 693
 694         err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_DCCP_MAX, attr,
 695                                           dccp_nla_policy, NULL);
 696         if (err < 0)
 697                 return err;
 698
 699         if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
 700             !tb[CTA_PROTOINFO_DCCP_ROLE] ||
 701             nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX ||
 702             nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) {
 703                 return -EINVAL;
 704         }
 705
 706         spin_lock_bh(&ct->lock);
 707         ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
 708         if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) {
 709                 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 710                 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 711         } else {
 712                 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER;
 713                 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT;
 714         }
 715         if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) {
 716                 ct->proto.dccp.handshake_seq =
 717                 be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]));
 718         }
 719         spin_unlock_bh(&ct->lock);
 720         return 0;
 721 }
 722 #endif
 723
 724 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 725
 726 #include <linux/netfilter/nfnetlink.h>
 727 #include <linux/netfilter/nfnetlink_cttimeout.h>
 728
 729 static int dccp_timeout_nlattr_to_obj(struct nlattr *tb[],
 730                                       struct net *net, void *data)
 731 {
 732         struct nf_dccp_net *dn = nf_dccp_pernet(net);
 733         unsigned int *timeouts = data;
 734         int i;
 735
 736         if (!timeouts)
 737                  timeouts = dn->dccp_timeout;
 738
 739         /* set default DCCP timeouts. */
 740         for (i=0; i<CT_DCCP_MAX; i++)
 741                 timeouts[i] = dn->dccp_timeout[i];
 742
 743         /* there's a 1:1 mapping between attributes and protocol states. */
 744         for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 745                 if (tb[i]) {
 746                         timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ;
 747                 }
 748         }
 749
 750         timeouts[CTA_TIMEOUT_DCCP_UNSPEC] = timeouts[CTA_TIMEOUT_DCCP_REQUEST];
 751         return 0;
 752 }
 753
 754 static int
 755 dccp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 756 {
 757         const unsigned int *timeouts = data;
 758         int i;
 759
 760         for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 761                 if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ)))
 762                         goto nla_put_failure;
 763         }
 764         return 0;
 765
 766 nla_put_failure:
 767         return -ENOSPC;
 768 }
 769
 770 static const struct nla_policy
 771 dccp_timeout_nla_policy[CTA_TIMEOUT_DCCP_MAX+1] = {
 772         [CTA_TIMEOUT_DCCP_REQUEST]      = { .type = NLA_U32 },
 773         [CTA_TIMEOUT_DCCP_RESPOND]      = { .type = NLA_U32 },
 774         [CTA_TIMEOUT_DCCP_PARTOPEN]     = { .type = NLA_U32 },
 775         [CTA_TIMEOUT_DCCP_OPEN]         = { .type = NLA_U32 },
 776         [CTA_TIMEOUT_DCCP_CLOSEREQ]     = { .type = NLA_U32 },
 777         [CTA_TIMEOUT_DCCP_CLOSING]      = { .type = NLA_U32 },
 778         [CTA_TIMEOUT_DCCP_TIMEWAIT]     = { .type = NLA_U32 },
 779 };
 780 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 781
 782 void nf_conntrack_dccp_init_net(struct net *net)
 783 {
 784         struct nf_dccp_net *dn = nf_dccp_pernet(net);
 785
 786         /* default values */
 787         dn->dccp_loose = 1;
 788         dn->dccp_timeout[CT_DCCP_REQUEST]       = 2 * DCCP_MSL;
 789         dn->dccp_timeout[CT_DCCP_RESPOND]       = 4 * DCCP_MSL;
 790         dn->dccp_timeout[CT_DCCP_PARTOPEN]      = 4 * DCCP_MSL;
 791         dn->dccp_timeout[CT_DCCP_OPEN]          = 12 * 3600 * HZ;
 792         dn->dccp_timeout[CT_DCCP_CLOSEREQ]      = 64 * HZ;
 793         dn->dccp_timeout[CT_DCCP_CLOSING]       = 64 * HZ;
 794         dn->dccp_timeout[CT_DCCP_TIMEWAIT]      = 2 * DCCP_MSL;
 795
 796         /* timeouts[0] is unused, make it same as SYN_SENT so
 797          * ->timeouts[0] contains 'new' timeout, like udp or icmp.
 798          */
 799         dn->dccp_timeout[CT_DCCP_NONE] = dn->dccp_timeout[CT_DCCP_REQUEST];
 800 }
 801
 802 const struct nf_conntrack_l4proto nf_conntrack_l4proto_dccp = {
 803         .l4proto                = IPPROTO_DCCP,
 804         .can_early_drop         = dccp_can_early_drop,
 805 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 806         .print_conntrack        = dccp_print_conntrack,
 807 #endif
 808 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 809         .nlattr_size            = DCCP_NLATTR_SIZE,
 810         .to_nlattr              = dccp_to_nlattr,
 811         .from_nlattr            = nlattr_to_dccp,
 812         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 813         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 814         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 815         .nla_policy             = nf_ct_port_nla_policy,
 816 #endif
 817 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 818         .ctnl_timeout           = {
 819                 .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
 820                 .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
 821                 .nlattr_max     = CTA_TIMEOUT_DCCP_MAX,
 822                 .obj_size       = sizeof(unsigned int) * CT_DCCP_MAX,
 823                 .nla_policy     = dccp_timeout_nla_policy,
 824         },
 825 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 826 };