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 dccp_hdr _dh, *dh;
 422         const char *msg;
 423         u_int8_t state;
 424
 425         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 426         BUG_ON(dh == NULL);
 427
 428         state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
 429         switch (state) {
 430         default:
 431                 if (nf_ct_dccp_loose == 0) {
 432                         msg = "nf_ct_dccp: not picking up existing connection ";
 433                         goto out_invalid;
 434                 }
 435         case CT_DCCP_REQUEST:
 436                 break;
 437         case CT_DCCP_INVALID:
 438                 msg = "nf_ct_dccp: invalid state transition ";
 439                 goto out_invalid;
 440         }
 441
 442         ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 443         ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 444         ct->proto.dccp.state = CT_DCCP_NONE;
 445         return true;
 446
 447 out_invalid:
 448         if (LOG_INVALID(IPPROTO_DCCP))
 449                 nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL, msg);
 450         return false;
 451 }
 452
 453 static u64 dccp_ack_seq(const struct dccp_hdr *dh)
 454 {
 455         const struct dccp_hdr_ack_bits *dhack;
 456
 457         dhack = (void *)dh + __dccp_basic_hdr_len(dh);
 458         return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
 459                      ntohl(dhack->dccph_ack_nr_low);
 460 }
 461
 462 static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
 463                        unsigned int dataoff, enum ip_conntrack_info ctinfo,
 464                        int pf, unsigned int hooknum)
 465 {
 466         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 467         struct dccp_hdr _dh, *dh;
 468         u_int8_t type, old_state, new_state;
 469         enum ct_dccp_roles role;
 470
 471         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 472         BUG_ON(dh == NULL);
 473         type = dh->dccph_type;
 474
 475         if (type == DCCP_PKT_RESET &&
 476             !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 477                 /* Tear down connection immediately if only reply is a RESET */
 478                 nf_ct_kill_acct(ct, ctinfo, skb);
 479                 return NF_ACCEPT;
 480         }
 481
 482         write_lock_bh(&dccp_lock);
 483
 484         role = ct->proto.dccp.role[dir];
 485         old_state = ct->proto.dccp.state;
 486         new_state = dccp_state_table[role][type][old_state];
 487
 488         switch (new_state) {
 489         case CT_DCCP_REQUEST:
 490                 if (old_state == CT_DCCP_TIMEWAIT &&
 491                     role == CT_DCCP_ROLE_SERVER) {
 492                         /* Reincarnation in the reverse direction: reopen and
 493                          * reverse client/server roles. */
 494                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
 495                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
 496                 }
 497                 break;
 498         case CT_DCCP_RESPOND:
 499                 if (old_state == CT_DCCP_REQUEST)
 500                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 501                 break;
 502         case CT_DCCP_PARTOPEN:
 503                 if (old_state == CT_DCCP_RESPOND &&
 504                     type == DCCP_PKT_ACK &&
 505                     dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
 506                         set_bit(IPS_ASSURED_BIT, &ct->status);
 507                 break;
 508         case CT_DCCP_IGNORE:
 509                 /*
 510                  * Connection tracking might be out of sync, so we ignore
 511                  * packets that might establish a new connection and resync
 512                  * if the server responds with a valid Response.
 513                  */
 514                 if (ct->proto.dccp.last_dir == !dir &&
 515                     ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
 516                     type == DCCP_PKT_RESPONSE) {
 517                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
 518                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
 519                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 520                         new_state = CT_DCCP_RESPOND;
 521                         break;
 522                 }
 523                 ct->proto.dccp.last_dir = dir;
 524                 ct->proto.dccp.last_pkt = type;
 525
 526                 write_unlock_bh(&dccp_lock);
 527                 if (LOG_INVALID(IPPROTO_DCCP))
 528                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 529                                       "nf_ct_dccp: invalid packet ignored ");
 530                 return NF_ACCEPT;
 531         case CT_DCCP_INVALID:
 532                 write_unlock_bh(&dccp_lock);
 533                 if (LOG_INVALID(IPPROTO_DCCP))
 534                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 535                                       "nf_ct_dccp: invalid state transition ");
 536                 return -NF_ACCEPT;
 537         }
 538
 539         ct->proto.dccp.last_dir = dir;
 540         ct->proto.dccp.last_pkt = type;
 541         ct->proto.dccp.state = new_state;
 542         write_unlock_bh(&dccp_lock);
 543         nf_ct_refresh_acct(ct, ctinfo, skb, dccp_timeout[new_state]);
 544
 545         return NF_ACCEPT;
 546 }
 547
 548 static int dccp_error(struct sk_buff *skb, unsigned int dataoff,
 549                       enum ip_conntrack_info *ctinfo, int pf,
 550                       unsigned int hooknum)
 551 {
 552         struct dccp_hdr _dh, *dh;
 553         unsigned int dccp_len = skb->len - dataoff;
 554         unsigned int cscov;
 555         const char *msg;
 556
 557         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 558         if (dh == NULL) {
 559                 msg = "nf_ct_dccp: short packet ";
 560                 goto out_invalid;
 561         }
 562
 563         if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
 564             dh->dccph_doff * 4 > dccp_len) {
 565                 msg = "nf_ct_dccp: truncated/malformed packet ";
 566                 goto out_invalid;
 567         }
 568
 569         cscov = dccp_len;
 570         if (dh->dccph_cscov) {
 571                 cscov = (dh->dccph_cscov - 1) * 4;
 572                 if (cscov > dccp_len) {
 573                         msg = "nf_ct_dccp: bad checksum coverage ";
 574                         goto out_invalid;
 575                 }
 576         }
 577
 578         if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
 579             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_DCCP,
 580                                 pf)) {
 581                 msg = "nf_ct_dccp: bad checksum ";
 582                 goto out_invalid;
 583         }
 584
 585         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 586                 msg = "nf_ct_dccp: reserved packet type ";
 587                 goto out_invalid;
 588         }
 589
 590         return NF_ACCEPT;
 591
 592 out_invalid:
 593         if (LOG_INVALID(IPPROTO_DCCP))
 594                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
 595         return -NF_ACCEPT;
 596 }
 597
 598 static int dccp_print_tuple(struct seq_file *s,
 599                             const struct nf_conntrack_tuple *tuple)
 600 {
 601         return seq_printf(s, "sport=%hu dport=%hu ",
 602                           ntohs(tuple->src.u.dccp.port),
 603                           ntohs(tuple->dst.u.dccp.port));
 604 }
 605
 606 static int dccp_print_conntrack(struct seq_file *s, const struct nf_conn *ct)
 607 {
 608         return seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
 609 }
 610
 611 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 612 static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
 613                           const struct nf_conn *ct)
 614 {
 615         struct nlattr *nest_parms;
 616
 617         read_lock_bh(&dccp_lock);
 618         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
 619         if (!nest_parms)
 620                 goto nla_put_failure;
 621         NLA_PUT_U8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state);
 622         nla_nest_end(skb, nest_parms);
 623         read_unlock_bh(&dccp_lock);
 624         return 0;
 625
 626 nla_put_failure:
 627         read_unlock_bh(&dccp_lock);
 628         return -1;
 629 }
 630
 631 static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
 632         [CTA_PROTOINFO_DCCP_STATE]      = { .type = NLA_U8 },
 633 };
 634
 635 static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
 636 {
 637         struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
 638         struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
 639         int err;
 640
 641         if (!attr)
 642                 return 0;
 643
 644         err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
 645                                dccp_nla_policy);
 646         if (err < 0)
 647                 return err;
 648
 649         if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
 650             nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE)
 651                 return -EINVAL;
 652
 653         write_lock_bh(&dccp_lock);
 654         ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
 655         write_unlock_bh(&dccp_lock);
 656         return 0;
 657 }
 658 #endif
 659
 660 #ifdef CONFIG_SYSCTL
 661 static unsigned int dccp_sysctl_table_users;
 662 static struct ctl_table_header *dccp_sysctl_header;
 663 static ctl_table dccp_sysctl_table[] = {
 664         {
 665                 .ctl_name       = CTL_UNNUMBERED,
 666                 .procname       = "nf_conntrack_dccp_timeout_request",
 667                 .data           = &dccp_timeout[CT_DCCP_REQUEST],
 668                 .maxlen         = sizeof(unsigned int),
 669                 .mode           = 0644,
 670                 .proc_handler   = proc_dointvec_jiffies,
 671         },
 672         {
 673                 .ctl_name       = CTL_UNNUMBERED,
 674                 .procname       = "nf_conntrack_dccp_timeout_respond",
 675                 .data           = &dccp_timeout[CT_DCCP_RESPOND],
 676                 .maxlen         = sizeof(unsigned int),
 677                 .mode           = 0644,
 678                 .proc_handler   = proc_dointvec_jiffies,
 679         },
 680         {
 681                 .ctl_name       = CTL_UNNUMBERED,
 682                 .procname       = "nf_conntrack_dccp_timeout_partopen",
 683                 .data           = &dccp_timeout[CT_DCCP_PARTOPEN],
 684                 .maxlen         = sizeof(unsigned int),
 685                 .mode           = 0644,
 686                 .proc_handler   = proc_dointvec_jiffies,
 687         },
 688         {
 689                 .ctl_name       = CTL_UNNUMBERED,
 690                 .procname       = "nf_conntrack_dccp_timeout_open",
 691                 .data           = &dccp_timeout[CT_DCCP_OPEN],
 692                 .maxlen         = sizeof(unsigned int),
 693                 .mode           = 0644,
 694                 .proc_handler   = proc_dointvec_jiffies,
 695         },
 696         {
 697                 .ctl_name       = CTL_UNNUMBERED,
 698                 .procname       = "nf_conntrack_dccp_timeout_closereq",
 699                 .data           = &dccp_timeout[CT_DCCP_CLOSEREQ],
 700                 .maxlen         = sizeof(unsigned int),
 701                 .mode           = 0644,
 702                 .proc_handler   = proc_dointvec_jiffies,
 703         },
 704         {
 705                 .ctl_name       = CTL_UNNUMBERED,
 706                 .procname       = "nf_conntrack_dccp_timeout_closing",
 707                 .data           = &dccp_timeout[CT_DCCP_CLOSING],
 708                 .maxlen         = sizeof(unsigned int),
 709                 .mode           = 0644,
 710                 .proc_handler   = proc_dointvec_jiffies,
 711         },
 712         {
 713                 .ctl_name       = CTL_UNNUMBERED,
 714                 .procname       = "nf_conntrack_dccp_timeout_timewait",
 715                 .data           = &dccp_timeout[CT_DCCP_TIMEWAIT],
 716                 .maxlen         = sizeof(unsigned int),
 717                 .mode           = 0644,
 718                 .proc_handler   = proc_dointvec_jiffies,
 719         },
 720         {
 721                 .ctl_name       = CTL_UNNUMBERED,
 722                 .procname       = "nf_conntrack_dccp_loose",
 723                 .data           = &nf_ct_dccp_loose,
 724                 .maxlen         = sizeof(nf_ct_dccp_loose),
 725                 .mode           = 0644,
 726                 .proc_handler   = proc_dointvec,
 727         },
 728         {
 729                 .ctl_name       = 0,
 730         }
 731 };
 732 #endif /* CONFIG_SYSCTL */
 733
 734 static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
 735         .l3proto                = AF_INET,
 736         .l4proto                = IPPROTO_DCCP,
 737         .name                   = "dccp",
 738         .pkt_to_tuple           = dccp_pkt_to_tuple,
 739         .invert_tuple           = dccp_invert_tuple,
 740         .new                    = dccp_new,
 741         .packet                 = dccp_packet,
 742         .error                  = dccp_error,
 743         .print_tuple            = dccp_print_tuple,
 744         .print_conntrack        = dccp_print_conntrack,
 745 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 746         .to_nlattr              = dccp_to_nlattr,
 747         .from_nlattr            = nlattr_to_dccp,
 748         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 749         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 750         .nla_policy             = nf_ct_port_nla_policy,
 751 #endif
 752 #ifdef CONFIG_SYSCTL
 753         .ctl_table_users        = &dccp_sysctl_table_users,
 754         .ctl_table_header       = &dccp_sysctl_header,
 755         .ctl_table              = dccp_sysctl_table,
 756 #endif
 757 };
 758
 759 static struct nf_conntrack_l4proto dccp_proto6 __read_mostly = {
 760         .l3proto                = AF_INET6,
 761         .l4proto                = IPPROTO_DCCP,
 762         .name                   = "dccp",
 763         .pkt_to_tuple           = dccp_pkt_to_tuple,
 764         .invert_tuple           = dccp_invert_tuple,
 765         .new                    = dccp_new,
 766         .packet                 = dccp_packet,
 767         .error                  = dccp_error,
 768         .print_tuple            = dccp_print_tuple,
 769         .print_conntrack        = dccp_print_conntrack,
 770 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 771         .to_nlattr              = dccp_to_nlattr,
 772         .from_nlattr            = nlattr_to_dccp,
 773         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 774         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 775         .nla_policy             = nf_ct_port_nla_policy,
 776 #endif
 777 #ifdef CONFIG_SYSCTL
 778         .ctl_table_users        = &dccp_sysctl_table_users,
 779         .ctl_table_header       = &dccp_sysctl_header,
 780         .ctl_table              = dccp_sysctl_table,
 781 #endif
 782 };
 783
 784 static int __init nf_conntrack_proto_dccp_init(void)
 785 {
 786         int err;
 787
 788         err = nf_conntrack_l4proto_register(&dccp_proto4);
 789         if (err < 0)
 790                 goto err1;
 791
 792         err = nf_conntrack_l4proto_register(&dccp_proto6);
 793         if (err < 0)
 794                 goto err2;
 795         return 0;
 796
 797 err2:
 798         nf_conntrack_l4proto_unregister(&dccp_proto4);
 799 err1:
 800         return err;
 801 }
 802
 803 static void __exit nf_conntrack_proto_dccp_fini(void)
 804 {
 805         nf_conntrack_l4proto_unregister(&dccp_proto6);
 806         nf_conntrack_l4proto_unregister(&dccp_proto4);
 807 }
 808
 809 module_init(nf_conntrack_proto_dccp_init);
 810 module_exit(nf_conntrack_proto_dccp_fini);
 811
 812 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 813 MODULE_DESCRIPTION("DCCP connection tracking protocol helper");
 814 MODULE_LICENSE("GPL");