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 #include <linux/slab.h>
  19
  20 #include <net/net_namespace.h>
  21 #include <net/netns/generic.h>
  22
  23 #include <linux/netfilter/nfnetlink_conntrack.h>
  24 #include <net/netfilter/nf_conntrack.h>
  25 #include <net/netfilter/nf_conntrack_l4proto.h>
  26 #include <net/netfilter/nf_conntrack_ecache.h>
  27 #include <net/netfilter/nf_log.h>
  28
  29 /* Timeouts are based on values from RFC4340:
  30  *
  31  * - REQUEST:
  32  *
  33  *   8.1.2. Client Request
  34  *
  35  *   A client MAY give up on its DCCP-Requests after some time
  36  *   (3 minutes, for example).
  37  *
  38  * - RESPOND:
  39  *
  40  *   8.1.3. Server Response
  41  *
  42  *   It MAY also leave the RESPOND state for CLOSED after a timeout of
  43  *   not less than 4MSL (8 minutes);
  44  *
  45  * - PARTOPEN:
  46  *
  47  *   8.1.5. Handshake Completion
  48  *
  49  *   If the client remains in PARTOPEN for more than 4MSL (8 minutes),
  50  *   it SHOULD reset the connection with Reset Code 2, "Aborted".
  51  *
  52  * - OPEN:
  53  *
  54  *   The DCCP timestamp overflows after 11.9 hours. If the connection
  55  *   stays idle this long the sequence number won't be recognized
  56  *   as valid anymore.
  57  *
  58  * - CLOSEREQ/CLOSING:
  59  *
  60  *   8.3. Termination
  61  *
  62  *   The retransmission timer should initially be set to go off in two
  63  *   round-trip times and should back off to not less than once every
  64  *   64 seconds ...
  65  *
  66  * - TIMEWAIT:
  67  *
  68  *   4.3. States
  69  *
  70  *   A server or client socket remains in this state for 2MSL (4 minutes)
  71  *   after the connection has been town down, ...
  72  */
  73
  74 #define DCCP_MSL (2 * 60 * HZ)
  75
  76 static const char * const dccp_state_names[] = {
  77         [CT_DCCP_NONE]          = "NONE",
  78         [CT_DCCP_REQUEST]       = "REQUEST",
  79         [CT_DCCP_RESPOND]       = "RESPOND",
  80         [CT_DCCP_PARTOPEN]      = "PARTOPEN",
  81         [CT_DCCP_OPEN]          = "OPEN",
  82         [CT_DCCP_CLOSEREQ]      = "CLOSEREQ",
  83         [CT_DCCP_CLOSING]       = "CLOSING",
  84         [CT_DCCP_TIMEWAIT]      = "TIMEWAIT",
  85         [CT_DCCP_IGNORE]        = "IGNORE",
  86         [CT_DCCP_INVALID]       = "INVALID",
  87 };
  88
  89 #define sNO     CT_DCCP_NONE
  90 #define sRQ     CT_DCCP_REQUEST
  91 #define sRS     CT_DCCP_RESPOND
  92 #define sPO     CT_DCCP_PARTOPEN
  93 #define sOP     CT_DCCP_OPEN
  94 #define sCR     CT_DCCP_CLOSEREQ
  95 #define sCG     CT_DCCP_CLOSING
  96 #define sTW     CT_DCCP_TIMEWAIT
  97 #define sIG     CT_DCCP_IGNORE
  98 #define sIV     CT_DCCP_INVALID
  99
 100 /*
 101  * DCCP state transition table
 102  *
 103  * The assumption is the same as for TCP tracking:
 104  *
 105  * We are the man in the middle. All the packets go through us but might
 106  * get lost in transit to the destination. It is assumed that the destination
 107  * can't receive segments we haven't seen.
 108  *
 109  * The following states exist:
 110  *
 111  * NONE:        Initial state, expecting Request
 112  * REQUEST:     Request seen, waiting for Response from server
 113  * RESPOND:     Response from server seen, waiting for Ack from client
 114  * PARTOPEN:    Ack after Response seen, waiting for packet other than Response,
 115  *              Reset or Sync from server
 116  * OPEN:        Packet other than Response, Reset or Sync seen
 117  * CLOSEREQ:    CloseReq from server seen, expecting Close from client
 118  * CLOSING:     Close seen, expecting Reset
 119  * TIMEWAIT:    Reset seen
 120  * IGNORE:      Not determinable whether packet is valid
 121  *
 122  * Some states exist only on one side of the connection: REQUEST, RESPOND,
 123  * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to
 124  * the one it was in before.
 125  *
 126  * Packets are marked as ignored (sIG) if we don't know if they're valid
 127  * (for example a reincarnation of a connection we didn't notice is dead
 128  * already) and the server may send back a connection closing Reset or a
 129  * Response. They're also used for Sync/SyncAck packets, which we don't
 130  * care about.
 131  */
 132 static const u_int8_t
 133 dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = {
 134         [CT_DCCP_ROLE_CLIENT] = {
 135                 [DCCP_PKT_REQUEST] = {
 136                 /*
 137                  * sNO -> sRQ           Regular Request
 138                  * sRQ -> sRQ           Retransmitted Request or reincarnation
 139                  * sRS -> sRS           Retransmitted Request (apparently Response
 140                  *                      got lost after we saw it) or reincarnation
 141                  * sPO -> sIG           Ignore, conntrack might be out of sync
 142                  * sOP -> sIG           Ignore, conntrack might be out of sync
 143                  * sCR -> sIG           Ignore, conntrack might be out of sync
 144                  * sCG -> sIG           Ignore, conntrack might be out of sync
 145                  * sTW -> sRQ           Reincarnation
 146                  *
 147                  *      sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */
 148                         sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ,
 149                 },
 150                 [DCCP_PKT_RESPONSE] = {
 151                 /*
 152                  * sNO -> sIV           Invalid
 153                  * sRQ -> sIG           Ignore, might be response to ignored Request
 154                  * sRS -> sIG           Ignore, might be response to ignored Request
 155                  * sPO -> sIG           Ignore, might be response to ignored Request
 156                  * sOP -> sIG           Ignore, might be response to ignored Request
 157                  * sCR -> sIG           Ignore, might be response to ignored Request
 158                  * sCG -> sIG           Ignore, might be response to ignored Request
 159                  * sTW -> sIV           Invalid, reincarnation in reverse direction
 160                  *                      goes through sRQ
 161                  *
 162                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 163                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV,
 164                 },
 165                 [DCCP_PKT_ACK] = {
 166                 /*
 167                  * sNO -> sIV           No connection
 168                  * sRQ -> sIV           No connection
 169                  * sRS -> sPO           Ack for Response, move to PARTOPEN (8.1.5.)
 170                  * sPO -> sPO           Retransmitted Ack for Response, remain in PARTOPEN
 171                  * sOP -> sOP           Regular ACK, remain in OPEN
 172                  * sCR -> sCR           Ack in CLOSEREQ MAY be processed (8.3.)
 173                  * sCG -> sCG           Ack in CLOSING MAY be processed (8.3.)
 174                  * sTW -> sIV
 175                  *
 176                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 177                         sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
 178                 },
 179                 [DCCP_PKT_DATA] = {
 180                 /*
 181                  * sNO -> sIV           No connection
 182                  * sRQ -> sIV           No connection
 183                  * sRS -> sIV           No connection
 184                  * sPO -> sIV           MUST use DataAck in PARTOPEN state (8.1.5.)
 185                  * sOP -> sOP           Regular Data packet
 186                  * sCR -> sCR           Data in CLOSEREQ MAY be processed (8.3.)
 187                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 188                  * sTW -> sIV
 189                  *
 190                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 191                         sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV,
 192                 },
 193                 [DCCP_PKT_DATAACK] = {
 194                 /*
 195                  * sNO -> sIV           No connection
 196                  * sRQ -> sIV           No connection
 197                  * sRS -> sPO           Ack for Response, move to PARTOPEN (8.1.5.)
 198                  * sPO -> sPO           Remain in PARTOPEN state
 199                  * sOP -> sOP           Regular DataAck packet in OPEN state
 200                  * sCR -> sCR           DataAck in CLOSEREQ MAY be processed (8.3.)
 201                  * sCG -> sCG           DataAck in CLOSING MAY be processed (8.3.)
 202                  * sTW -> sIV
 203                  *
 204                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 205                         sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
 206                 },
 207                 [DCCP_PKT_CLOSEREQ] = {
 208                 /*
 209                  * CLOSEREQ may only be sent by the server.
 210                  *
 211                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 212                         sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV
 213                 },
 214                 [DCCP_PKT_CLOSE] = {
 215                 /*
 216                  * sNO -> sIV           No connection
 217                  * sRQ -> sIV           No connection
 218                  * sRS -> sIV           No connection
 219                  * sPO -> sCG           Client-initiated close
 220                  * sOP -> sCG           Client-initiated close
 221                  * sCR -> sCG           Close in response to CloseReq (8.3.)
 222                  * sCG -> sCG           Retransmit
 223                  * sTW -> sIV           Late retransmit, already in TIME_WAIT
 224                  *
 225                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 226                         sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV
 227                 },
 228                 [DCCP_PKT_RESET] = {
 229                 /*
 230                  * sNO -> sIV           No connection
 231                  * sRQ -> sTW           Sync received or timeout, SHOULD send Reset (8.1.1.)
 232                  * sRS -> sTW           Response received without Request
 233                  * sPO -> sTW           Timeout, SHOULD send Reset (8.1.5.)
 234                  * sOP -> sTW           Connection reset
 235                  * sCR -> sTW           Connection reset
 236                  * sCG -> sTW           Connection reset
 237                  * sTW -> sIG           Ignore (don't refresh timer)
 238                  *
 239                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 240                         sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG
 241                 },
 242                 [DCCP_PKT_SYNC] = {
 243                 /*
 244                  * We currently ignore Sync packets
 245                  *
 246                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 247                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 248                 },
 249                 [DCCP_PKT_SYNCACK] = {
 250                 /*
 251                  * We currently ignore SyncAck packets
 252                  *
 253                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 254                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 255                 },
 256         },
 257         [CT_DCCP_ROLE_SERVER] = {
 258                 [DCCP_PKT_REQUEST] = {
 259                 /*
 260                  * sNO -> sIV           Invalid
 261                  * sRQ -> sIG           Ignore, conntrack might be out of sync
 262                  * sRS -> sIG           Ignore, conntrack might be out of sync
 263                  * sPO -> sIG           Ignore, conntrack might be out of sync
 264                  * sOP -> sIG           Ignore, conntrack might be out of sync
 265                  * sCR -> sIG           Ignore, conntrack might be out of sync
 266                  * sCG -> sIG           Ignore, conntrack might be out of sync
 267                  * sTW -> sRQ           Reincarnation, must reverse roles
 268                  *
 269                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 270                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ
 271                 },
 272                 [DCCP_PKT_RESPONSE] = {
 273                 /*
 274                  * sNO -> sIV           Response without Request
 275                  * sRQ -> sRS           Response to clients Request
 276                  * sRS -> sRS           Retransmitted Response (8.1.3. SHOULD NOT)
 277                  * sPO -> sIG           Response to an ignored Request or late retransmit
 278                  * sOP -> sIG           Ignore, might be response to ignored Request
 279                  * sCR -> sIG           Ignore, might be response to ignored Request
 280                  * sCG -> sIG           Ignore, might be response to ignored Request
 281                  * sTW -> sIV           Invalid, Request from client in sTW moves to sRQ
 282                  *
 283                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 284                         sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV
 285                 },
 286                 [DCCP_PKT_ACK] = {
 287                 /*
 288                  * sNO -> sIV           No connection
 289                  * sRQ -> sIV           No connection
 290                  * sRS -> sIV           No connection
 291                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 292                  * sOP -> sOP           Regular Ack in OPEN state
 293                  * sCR -> sIV           Waiting for Close from client
 294                  * sCG -> sCG           Ack in CLOSING MAY be processed (8.3.)
 295                  * sTW -> sIV
 296                  *
 297                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 298                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 299                 },
 300                 [DCCP_PKT_DATA] = {
 301                 /*
 302                  * sNO -> sIV           No connection
 303                  * sRQ -> sIV           No connection
 304                  * sRS -> sIV           No connection
 305                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 306                  * sOP -> sOP           Regular Data packet in OPEN state
 307                  * sCR -> sIV           Waiting for Close from client
 308                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 309                  * sTW -> sIV
 310                  *
 311                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 312                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 313                 },
 314                 [DCCP_PKT_DATAACK] = {
 315                 /*
 316                  * sNO -> sIV           No connection
 317                  * sRQ -> sIV           No connection
 318                  * sRS -> sIV           No connection
 319                  * sPO -> sOP           Enter OPEN state (8.1.5.)
 320                  * sOP -> sOP           Regular DataAck in OPEN state
 321                  * sCR -> sIV           Waiting for Close from client
 322                  * sCG -> sCG           Data in CLOSING MAY be processed (8.3.)
 323                  * sTW -> sIV
 324                  *
 325                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 326                         sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
 327                 },
 328                 [DCCP_PKT_CLOSEREQ] = {
 329                 /*
 330                  * sNO -> sIV           No connection
 331                  * sRQ -> sIV           No connection
 332                  * sRS -> sIV           No connection
 333                  * sPO -> sOP -> sCR    Move directly to CLOSEREQ (8.1.5.)
 334                  * sOP -> sCR           CloseReq in OPEN state
 335                  * sCR -> sCR           Retransmit
 336                  * sCG -> sCR           Simultaneous close, client sends another Close
 337                  * sTW -> sIV           Already closed
 338                  *
 339                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 340                         sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV
 341                 },
 342                 [DCCP_PKT_CLOSE] = {
 343                 /*
 344                  * sNO -> sIV           No connection
 345                  * sRQ -> sIV           No connection
 346                  * sRS -> sIV           No connection
 347                  * sPO -> sOP -> sCG    Move direcly to CLOSING
 348                  * sOP -> sCG           Move to CLOSING
 349                  * sCR -> sIV           Close after CloseReq is invalid
 350                  * sCG -> sCG           Retransmit
 351                  * sTW -> sIV           Already closed
 352                  *
 353                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 354                         sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV
 355                 },
 356                 [DCCP_PKT_RESET] = {
 357                 /*
 358                  * sNO -> sIV           No connection
 359                  * sRQ -> sTW           Reset in response to Request
 360                  * sRS -> sTW           Timeout, SHOULD send Reset (8.1.3.)
 361                  * sPO -> sTW           Timeout, SHOULD send Reset (8.1.3.)
 362                  * sOP -> sTW
 363                  * sCR -> sTW
 364                  * sCG -> sTW
 365                  * sTW -> sIG           Ignore (don't refresh timer)
 366                  *
 367                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */
 368                         sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG
 369                 },
 370                 [DCCP_PKT_SYNC] = {
 371                 /*
 372                  * We currently ignore Sync packets
 373                  *
 374                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 375                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 376                 },
 377                 [DCCP_PKT_SYNCACK] = {
 378                 /*
 379                  * We currently ignore SyncAck packets
 380                  *
 381                  *      sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
 382                         sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 383                 },
 384         },
 385 };
 386
 387 /* this module per-net specifics */
 388 static int dccp_net_id __read_mostly;
 389 struct dccp_net {
 390         int dccp_loose;
 391         unsigned int dccp_timeout[CT_DCCP_MAX + 1];
 392 #ifdef CONFIG_SYSCTL
 393         struct ctl_table_header *sysctl_header;
 394         struct ctl_table *sysctl_table;
 395 #endif
 396 };
 397
 398 static inline struct dccp_net *dccp_pernet(struct net *net)
 399 {
 400         return net_generic(net, dccp_net_id);
 401 }
 402
 403 static bool dccp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
 404                               struct nf_conntrack_tuple *tuple)
 405 {
 406         struct dccp_hdr _hdr, *dh;
 407
 408         dh = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 409         if (dh == NULL)
 410                 return false;
 411
 412         tuple->src.u.dccp.port = dh->dccph_sport;
 413         tuple->dst.u.dccp.port = dh->dccph_dport;
 414         return true;
 415 }
 416
 417 static bool dccp_invert_tuple(struct nf_conntrack_tuple *inv,
 418                               const struct nf_conntrack_tuple *tuple)
 419 {
 420         inv->src.u.dccp.port = tuple->dst.u.dccp.port;
 421         inv->dst.u.dccp.port = tuple->src.u.dccp.port;
 422         return true;
 423 }
 424
 425 static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
 426                      unsigned int dataoff, unsigned int *timeouts)
 427 {
 428         struct net *net = nf_ct_net(ct);
 429         struct dccp_net *dn;
 430         struct dccp_hdr _dh, *dh;
 431         const char *msg;
 432         u_int8_t state;
 433
 434         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 435         BUG_ON(dh == NULL);
 436
 437         state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
 438         switch (state) {
 439         default:
 440                 dn = dccp_pernet(net);
 441                 if (dn->dccp_loose == 0) {
 442                         msg = "nf_ct_dccp: not picking up existing connection ";
 443                         goto out_invalid;
 444                 }
 445         case CT_DCCP_REQUEST:
 446                 break;
 447         case CT_DCCP_INVALID:
 448                 msg = "nf_ct_dccp: invalid state transition ";
 449                 goto out_invalid;
 450         }
 451
 452         ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 453         ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 454         ct->proto.dccp.state = CT_DCCP_NONE;
 455         ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST;
 456         ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL;
 457         ct->proto.dccp.handshake_seq = 0;
 458         return true;
 459
 460 out_invalid:
 461         if (LOG_INVALID(net, IPPROTO_DCCP))
 462                 nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL, msg);
 463         return false;
 464 }
 465
 466 static u64 dccp_ack_seq(const struct dccp_hdr *dh)
 467 {
 468         const struct dccp_hdr_ack_bits *dhack;
 469
 470         dhack = (void *)dh + __dccp_basic_hdr_len(dh);
 471         return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
 472                      ntohl(dhack->dccph_ack_nr_low);
 473 }
 474
 475 static unsigned int *dccp_get_timeouts(struct net *net)
 476 {
 477         return dccp_pernet(net)->dccp_timeout;
 478 }
 479
 480 static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
 481                        unsigned int dataoff, enum ip_conntrack_info ctinfo,
 482                        u_int8_t pf, unsigned int hooknum,
 483                        unsigned int *timeouts)
 484 {
 485         struct net *net = nf_ct_net(ct);
 486         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 487         struct dccp_hdr _dh, *dh;
 488         u_int8_t type, old_state, new_state;
 489         enum ct_dccp_roles role;
 490
 491         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 492         BUG_ON(dh == NULL);
 493         type = dh->dccph_type;
 494
 495         if (type == DCCP_PKT_RESET &&
 496             !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 497                 /* Tear down connection immediately if only reply is a RESET */
 498                 nf_ct_kill_acct(ct, ctinfo, skb);
 499                 return NF_ACCEPT;
 500         }
 501
 502         spin_lock_bh(&ct->lock);
 503
 504         role = ct->proto.dccp.role[dir];
 505         old_state = ct->proto.dccp.state;
 506         new_state = dccp_state_table[role][type][old_state];
 507
 508         switch (new_state) {
 509         case CT_DCCP_REQUEST:
 510                 if (old_state == CT_DCCP_TIMEWAIT &&
 511                     role == CT_DCCP_ROLE_SERVER) {
 512                         /* Reincarnation in the reverse direction: reopen and
 513                          * reverse client/server roles. */
 514                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
 515                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
 516                 }
 517                 break;
 518         case CT_DCCP_RESPOND:
 519                 if (old_state == CT_DCCP_REQUEST)
 520                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 521                 break;
 522         case CT_DCCP_PARTOPEN:
 523                 if (old_state == CT_DCCP_RESPOND &&
 524                     type == DCCP_PKT_ACK &&
 525                     dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
 526                         set_bit(IPS_ASSURED_BIT, &ct->status);
 527                 break;
 528         case CT_DCCP_IGNORE:
 529                 /*
 530                  * Connection tracking might be out of sync, so we ignore
 531                  * packets that might establish a new connection and resync
 532                  * if the server responds with a valid Response.
 533                  */
 534                 if (ct->proto.dccp.last_dir == !dir &&
 535                     ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
 536                     type == DCCP_PKT_RESPONSE) {
 537                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
 538                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
 539                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 540                         new_state = CT_DCCP_RESPOND;
 541                         break;
 542                 }
 543                 ct->proto.dccp.last_dir = dir;
 544                 ct->proto.dccp.last_pkt = type;
 545
 546                 spin_unlock_bh(&ct->lock);
 547                 if (LOG_INVALID(net, IPPROTO_DCCP))
 548                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 549                                       "nf_ct_dccp: invalid packet ignored ");
 550                 return NF_ACCEPT;
 551         case CT_DCCP_INVALID:
 552                 spin_unlock_bh(&ct->lock);
 553                 if (LOG_INVALID(net, IPPROTO_DCCP))
 554                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 555                                       "nf_ct_dccp: invalid state transition ");
 556                 return -NF_ACCEPT;
 557         }
 558
 559         ct->proto.dccp.last_dir = dir;
 560         ct->proto.dccp.last_pkt = type;
 561         ct->proto.dccp.state = new_state;
 562         spin_unlock_bh(&ct->lock);
 563
 564         if (new_state != old_state)
 565                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
 566
 567         nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);
 568
 569         return NF_ACCEPT;
 570 }
 571
 572 static int dccp_error(struct net *net, struct nf_conn *tmpl,
 573                       struct sk_buff *skb, unsigned int dataoff,
 574                       enum ip_conntrack_info *ctinfo,
 575                       u_int8_t pf, unsigned int hooknum)
 576 {
 577         struct dccp_hdr _dh, *dh;
 578         unsigned int dccp_len = skb->len - dataoff;
 579         unsigned int cscov;
 580         const char *msg;
 581
 582         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 583         if (dh == NULL) {
 584                 msg = "nf_ct_dccp: short packet ";
 585                 goto out_invalid;
 586         }
 587
 588         if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
 589             dh->dccph_doff * 4 > dccp_len) {
 590                 msg = "nf_ct_dccp: truncated/malformed packet ";
 591                 goto out_invalid;
 592         }
 593
 594         cscov = dccp_len;
 595         if (dh->dccph_cscov) {
 596                 cscov = (dh->dccph_cscov - 1) * 4;
 597                 if (cscov > dccp_len) {
 598                         msg = "nf_ct_dccp: bad checksum coverage ";
 599                         goto out_invalid;
 600                 }
 601         }
 602
 603         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 604             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_DCCP,
 605                                 pf)) {
 606                 msg = "nf_ct_dccp: bad checksum ";
 607                 goto out_invalid;
 608         }
 609
 610         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 611                 msg = "nf_ct_dccp: reserved packet type ";
 612                 goto out_invalid;
 613         }
 614
 615         return NF_ACCEPT;
 616
 617 out_invalid:
 618         if (LOG_INVALID(net, IPPROTO_DCCP))
 619                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
 620         return -NF_ACCEPT;
 621 }
 622
 623 static int dccp_print_tuple(struct seq_file *s,
 624                             const struct nf_conntrack_tuple *tuple)
 625 {
 626         return seq_printf(s, "sport=%hu dport=%hu ",
 627                           ntohs(tuple->src.u.dccp.port),
 628                           ntohs(tuple->dst.u.dccp.port));
 629 }
 630
 631 static int dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 632 {
 633         return seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
 634 }
 635
 636 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 637 static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
 638                           struct nf_conn *ct)
 639 {
 640         struct nlattr *nest_parms;
 641
 642         spin_lock_bh(&ct->lock);
 643         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
 644         if (!nest_parms)
 645                 goto nla_put_failure;
 646         if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state) ||
 647             nla_put_u8(skb, CTA_PROTOINFO_DCCP_ROLE,
 648                        ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]) ||
 649             nla_put_be64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ,
 650                          cpu_to_be64(ct->proto.dccp.handshake_seq)))
 651                 goto nla_put_failure;
 652         nla_nest_end(skb, nest_parms);
 653         spin_unlock_bh(&ct->lock);
 654         return 0;
 655
 656 nla_put_failure:
 657         spin_unlock_bh(&ct->lock);
 658         return -1;
 659 }
 660
 661 static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
 662         [CTA_PROTOINFO_DCCP_STATE]      = { .type = NLA_U8 },
 663         [CTA_PROTOINFO_DCCP_ROLE]       = { .type = NLA_U8 },
 664         [CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 },
 665 };
 666
 667 static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
 668 {
 669         struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
 670         struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
 671         int err;
 672
 673         if (!attr)
 674                 return 0;
 675
 676         err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
 677                                dccp_nla_policy);
 678         if (err < 0)
 679                 return err;
 680
 681         if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
 682             !tb[CTA_PROTOINFO_DCCP_ROLE] ||
 683             nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX ||
 684             nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) {
 685                 return -EINVAL;
 686         }
 687
 688         spin_lock_bh(&ct->lock);
 689         ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
 690         if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) {
 691                 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 692                 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 693         } else {
 694                 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER;
 695                 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT;
 696         }
 697         if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) {
 698                 ct->proto.dccp.handshake_seq =
 699                 be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]));
 700         }
 701         spin_unlock_bh(&ct->lock);
 702         return 0;
 703 }
 704
 705 static int dccp_nlattr_size(void)
 706 {
 707         return nla_total_size(0)        /* CTA_PROTOINFO_DCCP */
 708                 + nla_policy_len(dccp_nla_policy, CTA_PROTOINFO_DCCP_MAX + 1);
 709 }
 710
 711 #endif
 712
 713 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 714
 715 #include <linux/netfilter/nfnetlink.h>
 716 #include <linux/netfilter/nfnetlink_cttimeout.h>
 717
 718 static int dccp_timeout_nlattr_to_obj(struct nlattr *tb[], void *data)
 719 {
 720         struct dccp_net *dn = dccp_pernet(&init_net);
 721         unsigned int *timeouts = data;
 722         int i;
 723
 724         /* set default DCCP timeouts. */
 725         for (i=0; i<CT_DCCP_MAX; i++)
 726                 timeouts[i] = dn->dccp_timeout[i];
 727
 728         /* there's a 1:1 mapping between attributes and protocol states. */
 729         for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 730                 if (tb[i]) {
 731                         timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ;
 732                 }
 733         }
 734         return 0;
 735 }
 736
 737 static int
 738 dccp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 739 {
 740         const unsigned int *timeouts = data;
 741         int i;
 742
 743         for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 744                 if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ)))
 745                         goto nla_put_failure;
 746         }
 747         return 0;
 748
 749 nla_put_failure:
 750         return -ENOSPC;
 751 }
 752
 753 static const struct nla_policy
 754 dccp_timeout_nla_policy[CTA_TIMEOUT_DCCP_MAX+1] = {
 755         [CTA_TIMEOUT_DCCP_REQUEST]      = { .type = NLA_U32 },
 756         [CTA_TIMEOUT_DCCP_RESPOND]      = { .type = NLA_U32 },
 757         [CTA_TIMEOUT_DCCP_PARTOPEN]     = { .type = NLA_U32 },
 758         [CTA_TIMEOUT_DCCP_OPEN]         = { .type = NLA_U32 },
 759         [CTA_TIMEOUT_DCCP_CLOSEREQ]     = { .type = NLA_U32 },
 760         [CTA_TIMEOUT_DCCP_CLOSING]      = { .type = NLA_U32 },
 761         [CTA_TIMEOUT_DCCP_TIMEWAIT]     = { .type = NLA_U32 },
 762 };
 763 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 764
 765 #ifdef CONFIG_SYSCTL
 766 /* template, data assigned later */
 767 static struct ctl_table dccp_sysctl_table[] = {
 768         {
 769                 .procname       = "nf_conntrack_dccp_timeout_request",
 770                 .maxlen         = sizeof(unsigned int),
 771                 .mode           = 0644,
 772                 .proc_handler   = proc_dointvec_jiffies,
 773         },
 774         {
 775                 .procname       = "nf_conntrack_dccp_timeout_respond",
 776                 .maxlen         = sizeof(unsigned int),
 777                 .mode           = 0644,
 778                 .proc_handler   = proc_dointvec_jiffies,
 779         },
 780         {
 781                 .procname       = "nf_conntrack_dccp_timeout_partopen",
 782                 .maxlen         = sizeof(unsigned int),
 783                 .mode           = 0644,
 784                 .proc_handler   = proc_dointvec_jiffies,
 785         },
 786         {
 787                 .procname       = "nf_conntrack_dccp_timeout_open",
 788                 .maxlen         = sizeof(unsigned int),
 789                 .mode           = 0644,
 790                 .proc_handler   = proc_dointvec_jiffies,
 791         },
 792         {
 793                 .procname       = "nf_conntrack_dccp_timeout_closereq",
 794                 .maxlen         = sizeof(unsigned int),
 795                 .mode           = 0644,
 796                 .proc_handler   = proc_dointvec_jiffies,
 797         },
 798         {
 799                 .procname       = "nf_conntrack_dccp_timeout_closing",
 800                 .maxlen         = sizeof(unsigned int),
 801                 .mode           = 0644,
 802                 .proc_handler   = proc_dointvec_jiffies,
 803         },
 804         {
 805                 .procname       = "nf_conntrack_dccp_timeout_timewait",
 806                 .maxlen         = sizeof(unsigned int),
 807                 .mode           = 0644,
 808                 .proc_handler   = proc_dointvec_jiffies,
 809         },
 810         {
 811                 .procname       = "nf_conntrack_dccp_loose",
 812                 .maxlen         = sizeof(int),
 813                 .mode           = 0644,
 814                 .proc_handler   = proc_dointvec,
 815         },
 816         { }
 817 };
 818 #endif /* CONFIG_SYSCTL */
 819
 820 static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
 821         .l3proto                = AF_INET,
 822         .l4proto                = IPPROTO_DCCP,
 823         .name                   = "dccp",
 824         .pkt_to_tuple           = dccp_pkt_to_tuple,
 825         .invert_tuple           = dccp_invert_tuple,
 826         .new                    = dccp_new,
 827         .packet                 = dccp_packet,
 828         .get_timeouts           = dccp_get_timeouts,
 829         .error                  = dccp_error,
 830         .print_tuple            = dccp_print_tuple,
 831         .print_conntrack        = dccp_print_conntrack,
 832 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 833         .to_nlattr              = dccp_to_nlattr,
 834         .nlattr_size            = dccp_nlattr_size,
 835         .from_nlattr            = nlattr_to_dccp,
 836         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 837         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 838         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 839         .nla_policy             = nf_ct_port_nla_policy,
 840 #endif
 841 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 842         .ctnl_timeout           = {
 843                 .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
 844                 .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
 845                 .nlattr_max     = CTA_TIMEOUT_DCCP_MAX,
 846                 .obj_size       = sizeof(unsigned int) * CT_DCCP_MAX,
 847                 .nla_policy     = dccp_timeout_nla_policy,
 848         },
 849 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 850 };
 851
 852 static struct nf_conntrack_l4proto dccp_proto6 __read_mostly = {
 853         .l3proto                = AF_INET6,
 854         .l4proto                = IPPROTO_DCCP,
 855         .name                   = "dccp",
 856         .pkt_to_tuple           = dccp_pkt_to_tuple,
 857         .invert_tuple           = dccp_invert_tuple,
 858         .new                    = dccp_new,
 859         .packet                 = dccp_packet,
 860         .get_timeouts           = dccp_get_timeouts,
 861         .error                  = dccp_error,
 862         .print_tuple            = dccp_print_tuple,
 863         .print_conntrack        = dccp_print_conntrack,
 864 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 865         .to_nlattr              = dccp_to_nlattr,
 866         .nlattr_size            = dccp_nlattr_size,
 867         .from_nlattr            = nlattr_to_dccp,
 868         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 869         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 870         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 871         .nla_policy             = nf_ct_port_nla_policy,
 872 #endif
 873 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 874         .ctnl_timeout           = {
 875                 .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
 876                 .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
 877                 .nlattr_max     = CTA_TIMEOUT_DCCP_MAX,
 878                 .obj_size       = sizeof(unsigned int) * CT_DCCP_MAX,
 879                 .nla_policy     = dccp_timeout_nla_policy,
 880         },
 881 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 882 };
 883
 884 static __net_init int dccp_net_init(struct net *net)
 885 {
 886         struct dccp_net *dn = dccp_pernet(net);
 887
 888         /* default values */
 889         dn->dccp_loose = 1;
 890         dn->dccp_timeout[CT_DCCP_REQUEST]       = 2 * DCCP_MSL;
 891         dn->dccp_timeout[CT_DCCP_RESPOND]       = 4 * DCCP_MSL;
 892         dn->dccp_timeout[CT_DCCP_PARTOPEN]      = 4 * DCCP_MSL;
 893         dn->dccp_timeout[CT_DCCP_OPEN]          = 12 * 3600 * HZ;
 894         dn->dccp_timeout[CT_DCCP_CLOSEREQ]      = 64 * HZ;
 895         dn->dccp_timeout[CT_DCCP_CLOSING]       = 64 * HZ;
 896         dn->dccp_timeout[CT_DCCP_TIMEWAIT]      = 2 * DCCP_MSL;
 897
 898 #ifdef CONFIG_SYSCTL
 899         dn->sysctl_table = kmemdup(dccp_sysctl_table,
 900                         sizeof(dccp_sysctl_table), GFP_KERNEL);
 901         if (!dn->sysctl_table)
 902                 return -ENOMEM;
 903
 904         dn->sysctl_table[0].data = &dn->dccp_timeout[CT_DCCP_REQUEST];
 905         dn->sysctl_table[1].data = &dn->dccp_timeout[CT_DCCP_RESPOND];
 906         dn->sysctl_table[2].data = &dn->dccp_timeout[CT_DCCP_PARTOPEN];
 907         dn->sysctl_table[3].data = &dn->dccp_timeout[CT_DCCP_OPEN];
 908         dn->sysctl_table[4].data = &dn->dccp_timeout[CT_DCCP_CLOSEREQ];
 909         dn->sysctl_table[5].data = &dn->dccp_timeout[CT_DCCP_CLOSING];
 910         dn->sysctl_table[6].data = &dn->dccp_timeout[CT_DCCP_TIMEWAIT];
 911         dn->sysctl_table[7].data = &dn->dccp_loose;
 912
 913         dn->sysctl_header = register_net_sysctl(net, "net/netfilter",
 914                                                 dn->sysctl_table);
 915         if (!dn->sysctl_header) {
 916                 kfree(dn->sysctl_table);
 917                 return -ENOMEM;
 918         }
 919 #endif
 920
 921         return 0;
 922 }
 923
 924 static __net_exit void dccp_net_exit(struct net *net)
 925 {
 926         struct dccp_net *dn = dccp_pernet(net);
 927 #ifdef CONFIG_SYSCTL
 928         unregister_net_sysctl_table(dn->sysctl_header);
 929         kfree(dn->sysctl_table);
 930 #endif
 931 }
 932
 933 static struct pernet_operations dccp_net_ops = {
 934         .init = dccp_net_init,
 935         .exit = dccp_net_exit,
 936         .id   = &dccp_net_id,
 937         .size = sizeof(struct dccp_net),
 938 };
 939
 940 static int __init nf_conntrack_proto_dccp_init(void)
 941 {
 942         int err;
 943
 944         err = register_pernet_subsys(&dccp_net_ops);
 945         if (err < 0)
 946                 goto err1;
 947
 948         err = nf_conntrack_l4proto_register(&dccp_proto4);
 949         if (err < 0)
 950                 goto err2;
 951
 952         err = nf_conntrack_l4proto_register(&dccp_proto6);
 953         if (err < 0)
 954                 goto err3;
 955         return 0;
 956
 957 err3:
 958         nf_conntrack_l4proto_unregister(&dccp_proto4);
 959 err2:
 960         unregister_pernet_subsys(&dccp_net_ops);
 961 err1:
 962         return err;
 963 }
 964
 965 static void __exit nf_conntrack_proto_dccp_fini(void)
 966 {
 967         unregister_pernet_subsys(&dccp_net_ops);
 968         nf_conntrack_l4proto_unregister(&dccp_proto6);
 969         nf_conntrack_l4proto_unregister(&dccp_proto4);
 970 }
 971
 972 module_init(nf_conntrack_proto_dccp_init);
 973 module_exit(nf_conntrack_proto_dccp_fini);
 974
 975 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 976 MODULE_DESCRIPTION("DCCP connection tracking protocol helper");
 977 MODULE_LICENSE("GPL");