net/netfilter/nf_conntrack_proto_dccp.c

   1 /*
   2  * DCCP connection tracking protocol helper
   3  *
   4  * Copyright (c) 2005, 2006, 2008 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/sysctl.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/dccp.h>
  18
  19 #include <linux/netfilter/nfnetlink_conntrack.h>
  20 #include <net/netfilter/nf_conntrack.h>
  21 #include <net/netfilter/nf_conntrack_l4proto.h>
  22 #include <net/netfilter/nf_log.h>
  23
  24 static DEFINE_RWLOCK(dccp_lock);
  25
  26 static int nf_ct_dccp_loose __read_mostly = 1;
  27
  28 /* Timeouts are based on values from RFC4340:
  29  *
  30  * - REQUEST:
  31  *
  32  *   8.1.2. Client Request
  33  *
  34  *   A client MAY give up on its DCCP-Requests after some time
  35  *   (3 minutes, for example).
  36  *
  37  * - RESPOND:
  38  *
  39  *   8.1.3. Server Response
  40  *
  41  *   It MAY also leave the RESPOND state for CLOSED after a timeout of
  42  *   not less than 4MSL (8 minutes);
  43  *
  44  * - PARTOPEN:
  45  *
  46  *   8.1.5. Handshake Completion
  47  *
  48  *   If the client remains in PARTOPEN for more than 4MSL (8 minutes),
  49  *   it SHOULD reset the connection with Reset Code 2, "Aborted".
  50  *
  51  * - OPEN:
  52  *
  53  *   The DCCP timestamp overflows after 11.9 hours. If the connection
  54  *   stays idle this long the sequence number won't be recognized
  55  *   as valid anymore.
  56  *
  57  * - CLOSEREQ/CLOSING:
  58  *
  59  *   8.3. Termination
  60  *
  61  *   The retransmission timer should initially be set to go off in two
  62  *   round-trip times and should back off to not less than once every
  63  *   64 seconds ...
  64  *
  65  * - TIMEWAIT:
  66  *
  67  *   4.3. States
  68  *
  69  *   A server or client socket remains in this state for 2MSL (4 minutes)
  70  *   after the connection has been town down, ...
  71  */
  72
  73 #define DCCP_MSL (2 * 60 * HZ)
  74
  75 static unsigned int dccp_timeout[CT_DCCP_MAX + 1] __read_mostly = {
  76         [CT_DCCP_REQUEST]       = 2 * DCCP_MSL,
  77         [CT_DCCP_RESPOND]       = 4 * DCCP_MSL,
  78         [CT_DCCP_PARTOPEN]      = 4 * DCCP_MSL,
  79         [CT_DCCP_OPEN]          = 12 * 3600 * HZ,
  80         [CT_DCCP_CLOSEREQ]      = 64 * HZ,
  81         [CT_DCCP_CLOSING]       = 64 * HZ,
  82         [CT_DCCP_TIMEWAIT]      = 2 * DCCP_MSL,
  83 };
  84
  85 static const char * const dccp_state_names[] = {
  86         [CT_DCCP_NONE]          = "NONE",
  87         [CT_DCCP_REQUEST]       = "REQUEST",
  88         [CT_DCCP_RESPOND]       = "RESPOND",
  89         [CT_DCCP_PARTOPEN]      = "PARTOPEN",
  90         [CT_DCCP_OPEN]          = "OPEN",
  91         [CT_DCCP_CLOSEREQ]      = "CLOSEREQ",
  92         [CT_DCCP_CLOSING]       = "CLOSING",
  93         [CT_DCCP_TIMEWAIT]      = "TIMEWAIT",
  94         [CT_DCCP_IGNORE]        = "IGNORE",
  95         [CT_DCCP_INVALID]       = "INVALID",
  96 };
  97
  98 #define sNO     CT_DCCP_NONE
  99 #define sRQ     CT_DCCP_REQUEST
 100 #define sRS     CT_DCCP_RESPOND
 101 #define sPO     CT_DCCP_PARTOPEN
 102 #define sOP     CT_DCCP_OPEN
 103 #define sCR     CT_DCCP_CLOSEREQ
 104 #define sCG     CT_DCCP_CLOSING
 105 #define sTW     CT_DCCP_TIMEWAIT
 106 #define sIG     CT_DCCP_IGNORE
 107 #define sIV     CT_DCCP_INVALID
 108
 109 /*
 110  * DCCP state transistion table
 111  *
 112  * The assumption is the same as for TCP tracking:
 113  *
 114  * We are the man in the middle. All the packets go through us but might
 115  * get lost in transit to the destination. It is assumed that the destination
 116  * can't receive segments we haven't seen.
 117  *
 118  * The following states exist:
 119  *
 120  * NONE:        Initial state, expecting Request
 121  * REQUEST:     Request seen, waiting for Response from server
 122  * RESPOND:     Response from server seen, waiting for Ack from client
 123  * PARTOPEN:    Ack after Response seen, waiting for packet other than Response,
 124  *              Reset or Sync from server
 125  * OPEN:        Packet other than Response, Reset or Sync seen
 126  * CLOSEREQ:    CloseReq from server seen, expecting Close from client
 127  * CLOSING:     Close seen, expecting Reset
 128  * TIMEWAIT:    Reset seen
 129  * IGNORE:      Not determinable whether packet is valid
 130  *
 131  * Some states exist only on one side of the connection: REQUEST, RESPOND,
 132  * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to
 133  * the one it was in before.
 134  *
 135  * Packets are marked as ignored (sIG) if we don't know if they're valid
 136  * (for example a reincarnation of a connection we didn't notice is dead
 137  * already) and the server may send back a connection closing Reset or a
 138  * Response. They're also used for Sync/SyncAck packets, which we don't
 139  * care about.
 140  */
 141 static const u_int8_t
 142 dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = {
 143         [CT_DCCP_ROLE_CLIENT] = {
 144                 [DCCP_PKT_REQUEST] = {
 145                 /*
 146                  * sNO -> sRQ           Regular Request
 147                  * sRQ -> sRQ           Retransmitted Request or reincarnation
 148                  * sRS -> sRS           Retransmitted Request (apparently Response
 149                  *                      got lost after we saw it) or reincarnation
 150                  * sPO -> sIG           Ignore, conntrack might be out of sync
 151                  * sOP -> sIG           Ignore, conntrack might be out of sync
 152                  * sCR -> sIG           Ignore, conntrack might be out of sync
 153                  * sCG -> sIG           Ignore, conntrack might be out of sync
 154                  * sTW -> sRQ           Reincarnation
 155                  *
 156                  *      sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */
 157                         sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ,
 158                 },
 159                 [DCCP_PKT_RESPONSE] = {
 160                 /*
 161                  * sNO -> sIV           Invalid
 162                  * sRQ -> sIG           Ignore, might be response to ignored Request
 163                  * sRS -> sIG           Ignore, might be response to ignored Request
 164                  * sPO -> sIG           Ignore, might be response to ignored Request
 165                  * sOP -> sIG           Ignore, might be response to ignored Request
 166                  * sCR -> sIG           Ignore, might be response to ignored Request
 167                  * sCG -> sIG           Ignore, might be response to ignored Request
 168                  * sTW -> sIV           Invalid, reincarnation in reverse direction
 169                  *                      goes through sRQ
 170                  *
 171                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 172                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV,
 173                 },
 174                 [DCCP_PKT_ACK] = {
 175                 /*
 176                  * sNO -> sIV           No connection
 177                  * sRQ -> sIV           No connection
 178                  * sRS -> sPO           Ack for Response, move to PARTOPEN (8.1.5.)
 179                  * sPO -> sPO           Retransmitted Ack for Response, remain in PARTOPEN
 180                  * sOP -> sOP           Regular ACK, remain in OPEN
 181                  * sCR -> sCR           Ack in CLOSEREQ MAY be processed (8.3.)
 182                  * sCG -> sCG           Ack in CLOSING MAY be processed (8.3.)
 183                  * sTW -> sIV
 184                  *
 185                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 186                         sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
 187                 },
 188                 [DCCP_PKT_DATA] = {
 189                 /*
 190                  * sNO -> sIV           No connection
 191                  * sRQ -> sIV           No connection
 192                  * sRS -> sIV           No connection
 193                  * sPO -> sIV           MUST use DataAck in PARTOPEN state (8.1.5.)
 194                  * sOP -> sOP           Regular Data packet
 195                  * sCR -> sCR           Data in CLOSEREQ MAY be processed (8.3.)
 196                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 197                  * sTW -> sIV
 198                  *
 199                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 200                         sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV,
 201                 },
 202                 [DCCP_PKT_DATAACK] = {
 203                 /*
 204                  * sNO -> sIV           No connection
 205                  * sRQ -> sIV           No connection
 206                  * sRS -> sPO           Ack for Response, move to PARTOPEN (8.1.5.)
 207                  * sPO -> sPO           Remain in PARTOPEN state
 208                  * sOP -> sOP           Regular DataAck packet in OPEN state
 209                  * sCR -> sCR           DataAck in CLOSEREQ MAY be processed (8.3.)
 210                  * sCG -> sCG           DataAck in CLOSING MAY be processed (8.3.)
 211                  * sTW -> sIV
 212                  *
 213                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 214                         sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
 215                 },
 216                 [DCCP_PKT_CLOSEREQ] = {
 217                 /*
 218                  * CLOSEREQ may only be sent by the server.
 219                  *
 220                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 221                         sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV
 222                 },
 223                 [DCCP_PKT_CLOSE] = {
 224                 /*
 225                  * sNO -> sIV           No connection
 226                  * sRQ -> sIV           No connection
 227                  * sRS -> sIV           No connection
 228                  * sPO -> sCG           Client-initiated close
 229                  * sOP -> sCG           Client-initiated close
 230                  * sCR -> sCG           Close in response to CloseReq (8.3.)
 231                  * sCG -> sCG           Retransmit
 232                  * sTW -> sIV           Late retransmit, already in TIME_WAIT
 233                  *
 234                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 235                         sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV
 236                 },
 237                 [DCCP_PKT_RESET] = {
 238                 /*
 239                  * sNO -> sIV           No connection
 240                  * sRQ -> sTW           Sync received or timeout, SHOULD send Reset (8.1.1.)
 241                  * sRS -> sTW           Response received without Request
 242                  * sPO -> sTW           Timeout, SHOULD send Reset (8.1.5.)
 243                  * sOP -> sTW           Connection reset
 244                  * sCR -> sTW           Connection reset
 245                  * sCG -> sTW           Connection reset
 246                  * sTW -> sIG           Ignore (don't refresh timer)
 247                  *
 248                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 249                         sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG
 250                 },
 251                 [DCCP_PKT_SYNC] = {
 252                 /*
 253                  * We currently ignore Sync packets
 254                  *
 255                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 256                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 257                 },
 258                 [DCCP_PKT_SYNCACK] = {
 259                 /*
 260                  * We currently ignore SyncAck packets
 261                  *
 262                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 263                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 264                 },
 265         },
 266         [CT_DCCP_ROLE_SERVER] = {
 267                 [DCCP_PKT_REQUEST] = {
 268                 /*
 269                  * sNO -> sIV           Invalid
 270                  * sRQ -> sIG           Ignore, conntrack might be out of sync
 271                  * sRS -> sIG           Ignore, conntrack might be out of sync
 272                  * sPO -> sIG           Ignore, conntrack might be out of sync
 273                  * sOP -> sIG           Ignore, conntrack might be out of sync
 274                  * sCR -> sIG           Ignore, conntrack might be out of sync
 275                  * sCG -> sIG           Ignore, conntrack might be out of sync
 276                  * sTW -> sRQ           Reincarnation, must reverse roles
 277                  *
 278                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 279                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ
 280                 },
 281                 [DCCP_PKT_RESPONSE] = {
 282                 /*
 283                  * sNO -> sIV           Response without Request
 284                  * sRQ -> sRS           Response to clients Request
 285                  * sRS -> sRS           Retransmitted Response (8.1.3. SHOULD NOT)
 286                  * sPO -> sIG           Response to an ignored Request or late retransmit
 287                  * sOP -> sIG           Ignore, might be response to ignored Request
 288                  * sCR -> sIG           Ignore, might be response to ignored Request
 289                  * sCG -> sIG           Ignore, might be response to ignored Request
 290                  * sTW -> sIV           Invalid, Request from client in sTW moves to sRQ
 291                  *
 292                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 293                         sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV
 294                 },
 295                 [DCCP_PKT_ACK] = {
 296                 /*
 297                  * sNO -> sIV           No connection
 298                  * sRQ -> sIV           No connection
 299                  * sRS -> sIV           No connection
 300                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 301                  * sOP -> sOP           Regular Ack in OPEN state
 302                  * sCR -> sIV           Waiting for Close from client
 303                  * sCG -> sCG           Ack in CLOSING MAY be processed (8.3.)
 304                  * sTW -> sIV
 305                  *
 306                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 307                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 308                 },
 309                 [DCCP_PKT_DATA] = {
 310                 /*
 311                  * sNO -> sIV           No connection
 312                  * sRQ -> sIV           No connection
 313                  * sRS -> sIV           No connection
 314                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 315                  * sOP -> sOP           Regular Data packet in OPEN state
 316                  * sCR -> sIV           Waiting for Close from client
 317                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 318                  * sTW -> sIV
 319                  *
 320                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 321                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 322                 },
 323                 [DCCP_PKT_DATAACK] = {
 324                 /*
 325                  * sNO -> sIV           No connection
 326                  * sRQ -> sIV           No connection
 327                  * sRS -> sIV           No connection
 328                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 329                  * sOP -> sOP           Regular DataAck in OPEN state
 330                  * sCR -> sIV           Waiting for Close from client
 331                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 332                  * sTW -> sIV
 333                  *
 334                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 335                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 336                 },
 337                 [DCCP_PKT_CLOSEREQ] = {
 338                 /*
 339                  * sNO -> sIV           No connection
 340                  * sRQ -> sIV           No connection
 341                  * sRS -> sIV           No connection
 342                  * sPO -> sOP -> sCR    Move directly to CLOSEREQ (8.1.5.)
 343                  * sOP -> sCR           CloseReq in OPEN state
 344                  * sCR -> sCR           Retransmit
 345                  * sCG -> sCR           Simultaneous close, client sends another Close
 346                  * sTW -> sIV           Already closed
 347                  *
 348                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 349                         sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV
 350                 },
 351                 [DCCP_PKT_CLOSE] = {
 352                 /*
 353                  * sNO -> sIV           No connection
 354                  * sRQ -> sIV           No connection
 355                  * sRS -> sIV           No connection
 356                  * sPO -> sOP -> sCG    Move direcly to CLOSING
 357                  * sOP -> sCG           Move to CLOSING
 358                  * sCR -> sIV           Close after CloseReq is invalid
 359                  * sCG -> sCG           Retransmit
 360                  * sTW -> sIV           Already closed
 361                  *
 362                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 363                         sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV
 364                 },
 365                 [DCCP_PKT_RESET] = {
 366                 /*
 367                  * sNO -> sIV           No connection
 368                  * sRQ -> sTW           Reset in response to Request
 369                  * sRS -> sTW           Timeout, SHOULD send Reset (8.1.3.)
 370                  * sPO -> sTW           Timeout, SHOULD send Reset (8.1.3.)
 371                  * sOP -> sTW
 372                  * sCR -> sTW
 373                  * sCG -> sTW
 374                  * sTW -> sIG           Ignore (don't refresh timer)
 375                  *
 376                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */
 377                         sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG
 378                 },
 379                 [DCCP_PKT_SYNC] = {
 380                 /*
 381                  * We currently ignore Sync packets
 382                  *
 383                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 384                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 385                 },
 386                 [DCCP_PKT_SYNCACK] = {
 387                 /*
 388                  * We currently ignore SyncAck packets
 389                  *
 390                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 391                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 392                 },
 393         },
 394 };
 395
 396 static bool dccp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
 397                               struct nf_conntrack_tuple *tuple)
 398 {
 399         struct dccp_hdr _hdr, *dh;
 400
 401         dh = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 402         if (dh == NULL)
 403                 return false;
 404
 405         tuple->src.u.dccp.port = dh->dccph_sport;
 406         tuple->dst.u.dccp.port = dh->dccph_dport;
 407         return true;
 408 }
 409
 410 static bool dccp_invert_tuple(struct nf_conntrack_tuple *inv,
 411                               const struct nf_conntrack_tuple *tuple)
 412 {
 413         inv->src.u.dccp.port = tuple->dst.u.dccp.port;
 414         inv->dst.u.dccp.port = tuple->src.u.dccp.port;
 415         return true;
 416 }
 417
 418 static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
 419                      unsigned int dataoff)
 420 {
 421         struct net *net = nf_ct_net(ct);
 422         struct dccp_hdr _dh, *dh;
 423         const char *msg;
 424         u_int8_t state;
 425
 426         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 427         BUG_ON(dh == NULL);
 428
 429         state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
 430         switch (state) {
 431         default:
 432                 if (nf_ct_dccp_loose == 0) {
 433                         msg = "nf_ct_dccp: not picking up existing connection ";
 434                         goto out_invalid;
 435                 }
 436         case CT_DCCP_REQUEST:
 437                 break;
 438         case CT_DCCP_INVALID:
 439                 msg = "nf_ct_dccp: invalid state transition ";
 440                 goto out_invalid;
 441         }
 442
 443         ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 444         ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 445         ct->proto.dccp.state = CT_DCCP_NONE;
 446         return true;
 447
 448 out_invalid:
 449         if (LOG_INVALID(net, IPPROTO_DCCP))
 450                 nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL, msg);
 451         return false;
 452 }
 453
 454 static u64 dccp_ack_seq(const struct dccp_hdr *dh)
 455 {
 456         const struct dccp_hdr_ack_bits *dhack;
 457
 458         dhack = (void *)dh + __dccp_basic_hdr_len(dh);
 459         return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
 460                      ntohl(dhack->dccph_ack_nr_low);
 461 }
 462
 463 static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
 464                        unsigned int dataoff, enum ip_conntrack_info ctinfo,
 465                        u_int8_t pf, unsigned int hooknum)
 466 {
 467         struct net *net = nf_ct_net(ct);
 468         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 469         struct dccp_hdr _dh, *dh;
 470         u_int8_t type, old_state, new_state;
 471         enum ct_dccp_roles role;
 472
 473         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 474         BUG_ON(dh == NULL);
 475         type = dh->dccph_type;
 476
 477         if (type == DCCP_PKT_RESET &&
 478             !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 479                 /* Tear down connection immediately if only reply is a RESET */
 480                 nf_ct_kill_acct(ct, ctinfo, skb);
 481                 return NF_ACCEPT;
 482         }
 483
 484         write_lock_bh(&dccp_lock);
 485
 486         role = ct->proto.dccp.role[dir];
 487         old_state = ct->proto.dccp.state;
 488         new_state = dccp_state_table[role][type][old_state];
 489
 490         switch (new_state) {
 491         case CT_DCCP_REQUEST:
 492                 if (old_state == CT_DCCP_TIMEWAIT &&
 493                     role == CT_DCCP_ROLE_SERVER) {
 494                         /* Reincarnation in the reverse direction: reopen and
 495                          * reverse client/server roles. */
 496                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
 497                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
 498                 }
 499                 break;
 500         case CT_DCCP_RESPOND:
 501                 if (old_state == CT_DCCP_REQUEST)
 502                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 503                 break;
 504         case CT_DCCP_PARTOPEN:
 505                 if (old_state == CT_DCCP_RESPOND &&
 506                     type == DCCP_PKT_ACK &&
 507                     dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
 508                         set_bit(IPS_ASSURED_BIT, &ct->status);
 509                 break;
 510         case CT_DCCP_IGNORE:
 511                 /*
 512                  * Connection tracking might be out of sync, so we ignore
 513                  * packets that might establish a new connection and resync
 514                  * if the server responds with a valid Response.
 515                  */
 516                 if (ct->proto.dccp.last_dir == !dir &&
 517                     ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
 518                     type == DCCP_PKT_RESPONSE) {
 519                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
 520                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
 521                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 522                         new_state = CT_DCCP_RESPOND;
 523                         break;
 524                 }
 525                 ct->proto.dccp.last_dir = dir;
 526                 ct->proto.dccp.last_pkt = type;
 527
 528                 write_unlock_bh(&dccp_lock);
 529                 if (LOG_INVALID(net, IPPROTO_DCCP))
 530                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 531                                       "nf_ct_dccp: invalid packet ignored ");
 532                 return NF_ACCEPT;
 533         case CT_DCCP_INVALID:
 534                 write_unlock_bh(&dccp_lock);
 535                 if (LOG_INVALID(net, IPPROTO_DCCP))
 536                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 537                                       "nf_ct_dccp: invalid state transition ");
 538                 return -NF_ACCEPT;
 539         }
 540
 541         ct->proto.dccp.last_dir = dir;
 542         ct->proto.dccp.last_pkt = type;
 543         ct->proto.dccp.state = new_state;
 544         write_unlock_bh(&dccp_lock);
 545         nf_ct_refresh_acct(ct, ctinfo, skb, dccp_timeout[new_state]);
 546
 547         return NF_ACCEPT;
 548 }
 549
 550 static int dccp_error(struct net *net, struct sk_buff *skb,
 551                       unsigned int dataoff, enum ip_conntrack_info *ctinfo,
 552                       u_int8_t pf, unsigned int hooknum)
 553 {
 554         struct dccp_hdr _dh, *dh;
 555         unsigned int dccp_len = skb->len - dataoff;
 556         unsigned int cscov;
 557         const char *msg;
 558
 559         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 560         if (dh == NULL) {
 561                 msg = "nf_ct_dccp: short packet ";
 562                 goto out_invalid;
 563         }
 564
 565         if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
 566             dh->dccph_doff * 4 > dccp_len) {
 567                 msg = "nf_ct_dccp: truncated/malformed packet ";
 568                 goto out_invalid;
 569         }
 570
 571         cscov = dccp_len;
 572         if (dh->dccph_cscov) {
 573                 cscov = (dh->dccph_cscov - 1) * 4;
 574                 if (cscov > dccp_len) {
 575                         msg = "nf_ct_dccp: bad checksum coverage ";
 576                         goto out_invalid;
 577                 }
 578         }
 579
 580         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 581             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_DCCP,
 582                                 pf)) {
 583                 msg = "nf_ct_dccp: bad checksum ";
 584                 goto out_invalid;
 585         }
 586
 587         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 588                 msg = "nf_ct_dccp: reserved packet type ";
 589                 goto out_invalid;
 590         }
 591
 592         return NF_ACCEPT;
 593
 594 out_invalid:
 595         if (LOG_INVALID(net, IPPROTO_DCCP))
 596                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
 597         return -NF_ACCEPT;
 598 }
 599
 600 static int dccp_print_tuple(struct seq_file *s,
 601                             const struct nf_conntrack_tuple *tuple)
 602 {
 603         return seq_printf(s, "sport=%hu dport=%hu ",
 604                           ntohs(tuple->src.u.dccp.port),
 605                           ntohs(tuple->dst.u.dccp.port));
 606 }
 607
 608 static int dccp_print_conntrack(struct seq_file *s, const struct nf_conn *ct)
 609 {
 610         return seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
 611 }
 612
 613 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 614 static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
 615                           const struct nf_conn *ct)
 616 {
 617         struct nlattr *nest_parms;
 618
 619         read_lock_bh(&dccp_lock);
 620         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
 621         if (!nest_parms)
 622                 goto nla_put_failure;
 623         NLA_PUT_U8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state);
 624         nla_nest_end(skb, nest_parms);
 625         read_unlock_bh(&dccp_lock);
 626         return 0;
 627
 628 nla_put_failure:
 629         read_unlock_bh(&dccp_lock);
 630         return -1;
 631 }
 632
 633 static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
 634         [CTA_PROTOINFO_DCCP_STATE]      = { .type = NLA_U8 },
 635 };
 636
 637 static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
 638 {
 639         struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
 640         struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
 641         int err;
 642
 643         if (!attr)
 644                 return 0;
 645
 646         err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
 647                                dccp_nla_policy);
 648         if (err < 0)
 649                 return err;
 650
 651         if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
 652             nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE)
 653                 return -EINVAL;
 654
 655         write_lock_bh(&dccp_lock);
 656         ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
 657         write_unlock_bh(&dccp_lock);
 658         return 0;
 659 }
 660 #endif
 661
 662 #ifdef CONFIG_SYSCTL
 663 static unsigned int dccp_sysctl_table_users;
 664 static struct ctl_table_header *dccp_sysctl_header;
 665 static ctl_table dccp_sysctl_table[] = {
 666         {
 667                 .ctl_name       = CTL_UNNUMBERED,
 668                 .procname       = "nf_conntrack_dccp_timeout_request",
 669                 .data           = &dccp_timeout[CT_DCCP_REQUEST],
 670                 .maxlen         = sizeof(unsigned int),
 671                 .mode           = 0644,
 672                 .proc_handler   = proc_dointvec_jiffies,
 673         },
 674         {
 675                 .ctl_name       = CTL_UNNUMBERED,
 676                 .procname       = "nf_conntrack_dccp_timeout_respond",
 677                 .data           = &dccp_timeout[CT_DCCP_RESPOND],
 678                 .maxlen         = sizeof(unsigned int),
 679                 .mode           = 0644,
 680                 .proc_handler   = proc_dointvec_jiffies,
 681         },
 682         {
 683                 .ctl_name       = CTL_UNNUMBERED,
 684                 .procname       = "nf_conntrack_dccp_timeout_partopen",
 685                 .data           = &dccp_timeout[CT_DCCP_PARTOPEN],
 686                 .maxlen         = sizeof(unsigned int),
 687                 .mode           = 0644,
 688                 .proc_handler   = proc_dointvec_jiffies,
 689         },
 690         {
 691                 .ctl_name       = CTL_UNNUMBERED,
 692                 .procname       = "nf_conntrack_dccp_timeout_open",
 693                 .data           = &dccp_timeout[CT_DCCP_OPEN],
 694                 .maxlen         = sizeof(unsigned int),
 695                 .mode           = 0644,
 696                 .proc_handler   = proc_dointvec_jiffies,
 697         },
 698         {
 699                 .ctl_name       = CTL_UNNUMBERED,
 700                 .procname       = "nf_conntrack_dccp_timeout_closereq",
 701                 .data           = &dccp_timeout[CT_DCCP_CLOSEREQ],
 702                 .maxlen         = sizeof(unsigned int),
 703                 .mode           = 0644,
 704                 .proc_handler   = proc_dointvec_jiffies,
 705         },
 706         {
 707                 .ctl_name       = CTL_UNNUMBERED,
 708                 .procname       = "nf_conntrack_dccp_timeout_closing",
 709                 .data           = &dccp_timeout[CT_DCCP_CLOSING],
 710                 .maxlen         = sizeof(unsigned int),
 711                 .mode           = 0644,
 712                 .proc_handler   = proc_dointvec_jiffies,
 713         },
 714         {
 715                 .ctl_name       = CTL_UNNUMBERED,
 716                 .procname       = "nf_conntrack_dccp_timeout_timewait",
 717                 .data           = &dccp_timeout[CT_DCCP_TIMEWAIT],
 718                 .maxlen         = sizeof(unsigned int),
 719                 .mode           = 0644,
 720                 .proc_handler   = proc_dointvec_jiffies,
 721         },
 722         {
 723                 .ctl_name       = CTL_UNNUMBERED,
 724                 .procname       = "nf_conntrack_dccp_loose",
 725                 .data           = &nf_ct_dccp_loose,
 726                 .maxlen         = sizeof(nf_ct_dccp_loose),
 727                 .mode           = 0644,
 728                 .proc_handler   = proc_dointvec,
 729         },
 730         {
 731                 .ctl_name       = 0,
 732         }
 733 };
 734 #endif /* CONFIG_SYSCTL */
 735
 736 static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
 737         .l3proto                = AF_INET,
 738         .l4proto                = IPPROTO_DCCP,
 739         .name                   = "dccp",
 740         .pkt_to_tuple           = dccp_pkt_to_tuple,
 741         .invert_tuple           = dccp_invert_tuple,
 742         .new                    = dccp_new,
 743         .packet                 = dccp_packet,
 744         .error                  = dccp_error,
 745         .print_tuple            = dccp_print_tuple,
 746         .print_conntrack        = dccp_print_conntrack,
 747 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 748         .to_nlattr              = dccp_to_nlattr,
 749         .from_nlattr            = nlattr_to_dccp,
 750         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 751         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 752         .nla_policy             = nf_ct_port_nla_policy,
 753 #endif
 754 #ifdef CONFIG_SYSCTL
 755         .ctl_table_users        = &dccp_sysctl_table_users,
 756         .ctl_table_header       = &dccp_sysctl_header,
 757         .ctl_table              = dccp_sysctl_table,
 758 #endif
 759 };
 760
 761 static struct nf_conntrack_l4proto dccp_proto6 __read_mostly = {
 762         .l3proto                = AF_INET6,
 763         .l4proto                = IPPROTO_DCCP,
 764         .name                   = "dccp",
 765         .pkt_to_tuple           = dccp_pkt_to_tuple,
 766         .invert_tuple           = dccp_invert_tuple,
 767         .new                    = dccp_new,
 768         .packet                 = dccp_packet,
 769         .error                  = dccp_error,
 770         .print_tuple            = dccp_print_tuple,
 771         .print_conntrack        = dccp_print_conntrack,
 772 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 773         .to_nlattr              = dccp_to_nlattr,
 774         .from_nlattr            = nlattr_to_dccp,
 775         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 776         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 777         .nla_policy             = nf_ct_port_nla_policy,
 778 #endif
 779 #ifdef CONFIG_SYSCTL
 780         .ctl_table_users        = &dccp_sysctl_table_users,
 781         .ctl_table_header       = &dccp_sysctl_header,
 782         .ctl_table              = dccp_sysctl_table,
 783 #endif
 784 };
 785
 786 static int __init nf_conntrack_proto_dccp_init(void)
 787 {
 788         int err;
 789
 790         err = nf_conntrack_l4proto_register(&dccp_proto4);
 791         if (err < 0)
 792                 goto err1;
 793
 794         err = nf_conntrack_l4proto_register(&dccp_proto6);
 795         if (err < 0)
 796                 goto err2;
 797         return 0;
 798
 799 err2:
 800         nf_conntrack_l4proto_unregister(&dccp_proto4);
 801 err1:
 802         return err;
 803 }
 804
 805 static void __exit nf_conntrack_proto_dccp_fini(void)
 806 {
 807         nf_conntrack_l4proto_unregister(&dccp_proto6);
 808         nf_conntrack_l4proto_unregister(&dccp_proto4);
 809 }
 810
 811 module_init(nf_conntrack_proto_dccp_init);
 812 module_exit(nf_conntrack_proto_dccp_fini);
 813
 814 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 815 MODULE_DESCRIPTION("DCCP connection tracking protocol helper");
 816 MODULE_LICENSE("GPL");