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/init.h>
  13 #include <linux/sysctl.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/dccp.h>
  17 #include <linux/slab.h>
  18
  19 #include <net/net_namespace.h>
  20 #include <net/netns/generic.h>
  21
  22 #include <linux/netfilter/nfnetlink_conntrack.h>
  23 #include <net/netfilter/nf_conntrack.h>
  24 #include <net/netfilter/nf_conntrack_l4proto.h>
  25 #include <net/netfilter/nf_conntrack_ecache.h>
  26 #include <net/netfilter/nf_conntrack_timeout.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                         sIV, 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                         sIV, 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                         sIV, 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                         sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
 383                 },
 384         },
 385 };
 386
 387 static noinline bool
 388 dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
 389          const struct dccp_hdr *dh)
 390 {
 391         struct net *net = nf_ct_net(ct);
 392         struct nf_dccp_net *dn;
 393         const char *msg;
 394         u_int8_t state;
 395
 396         state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
 397         switch (state) {
 398         default:
 399                 dn = nf_dccp_pernet(net);
 400                 if (dn->dccp_loose == 0) {
 401                         msg = "not picking up existing connection ";
 402                         goto out_invalid;
 403                 }
 404         case CT_DCCP_REQUEST:
 405                 break;
 406         case CT_DCCP_INVALID:
 407                 msg = "invalid state transition ";
 408                 goto out_invalid;
 409         }
 410
 411         ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 412         ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 413         ct->proto.dccp.state = CT_DCCP_NONE;
 414         ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST;
 415         ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL;
 416         ct->proto.dccp.handshake_seq = 0;
 417         return true;
 418
 419 out_invalid:
 420         nf_ct_l4proto_log_invalid(skb, ct, "%s", msg);
 421         return false;
 422 }
 423
 424 static u64 dccp_ack_seq(const struct dccp_hdr *dh)
 425 {
 426         const struct dccp_hdr_ack_bits *dhack;
 427
 428         dhack = (void *)dh + __dccp_basic_hdr_len(dh);
 429         return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
 430                      ntohl(dhack->dccph_ack_nr_low);
 431 }
 432
 433 static bool dccp_error(const struct dccp_hdr *dh,
 434                        struct sk_buff *skb, unsigned int dataoff,
 435                        const struct nf_hook_state *state)
 436 {
 437         unsigned int dccp_len = skb->len - dataoff;
 438         unsigned int cscov;
 439         const char *msg;
 440
 441         if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
 442             dh->dccph_doff * 4 > dccp_len) {
 443                 msg = "nf_ct_dccp: truncated/malformed packet ";
 444                 goto out_invalid;
 445         }
 446
 447         cscov = dccp_len;
 448         if (dh->dccph_cscov) {
 449                 cscov = (dh->dccph_cscov - 1) * 4;
 450                 if (cscov > dccp_len) {
 451                         msg = "nf_ct_dccp: bad checksum coverage ";
 452                         goto out_invalid;
 453                 }
 454         }
 455
 456         if (state->hook == NF_INET_PRE_ROUTING &&
 457             state->net->ct.sysctl_checksum &&
 458             nf_checksum_partial(skb, state->hook, dataoff, cscov,
 459                                 IPPROTO_DCCP, state->pf)) {
 460                 msg = "nf_ct_dccp: bad checksum ";
 461                 goto out_invalid;
 462         }
 463
 464         if (dh->dccph_type >= DCCP_PKT_INVALID) {
 465                 msg = "nf_ct_dccp: reserved packet type ";
 466                 goto out_invalid;
 467         }
 468         return false;
 469 out_invalid:
 470         nf_l4proto_log_invalid(skb, state->net, state->pf,
 471                                IPPROTO_DCCP, "%s", msg);
 472         return true;
 473 }
 474
 475 int nf_conntrack_dccp_packet(struct nf_conn *ct, struct sk_buff *skb,
 476                              unsigned int dataoff,
 477                              enum ip_conntrack_info ctinfo,
 478                              const struct nf_hook_state *state)
 479 {
 480         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 481         struct dccp_hdr _dh, *dh;
 482         u_int8_t type, old_state, new_state;
 483         enum ct_dccp_roles role;
 484         unsigned int *timeouts;
 485
 486         dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
 487         if (!dh)
 488                 return NF_DROP;
 489
 490         if (dccp_error(dh, skb, dataoff, state))
 491                 return -NF_ACCEPT;
 492
 493         type = dh->dccph_type;
 494         if (!nf_ct_is_confirmed(ct) && !dccp_new(ct, skb, dh))
 495                 return -NF_ACCEPT;
 496
 497         if (type == DCCP_PKT_RESET &&
 498             !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 499                 /* Tear down connection immediately if only reply is a RESET */
 500                 nf_ct_kill_acct(ct, ctinfo, skb);
 501                 return NF_ACCEPT;
 502         }
 503
 504         spin_lock_bh(&ct->lock);
 505
 506         role = ct->proto.dccp.role[dir];
 507         old_state = ct->proto.dccp.state;
 508         new_state = dccp_state_table[role][type][old_state];
 509
 510         switch (new_state) {
 511         case CT_DCCP_REQUEST:
 512                 if (old_state == CT_DCCP_TIMEWAIT &&
 513                     role == CT_DCCP_ROLE_SERVER) {
 514                         /* Reincarnation in the reverse direction: reopen and
 515                          * reverse client/server roles. */
 516                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
 517                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
 518                 }
 519                 break;
 520         case CT_DCCP_RESPOND:
 521                 if (old_state == CT_DCCP_REQUEST)
 522                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 523                 break;
 524         case CT_DCCP_PARTOPEN:
 525                 if (old_state == CT_DCCP_RESPOND &&
 526                     type == DCCP_PKT_ACK &&
 527                     dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
 528                         set_bit(IPS_ASSURED_BIT, &ct->status);
 529                 break;
 530         case CT_DCCP_IGNORE:
 531                 /*
 532                  * Connection tracking might be out of sync, so we ignore
 533                  * packets that might establish a new connection and resync
 534                  * if the server responds with a valid Response.
 535                  */
 536                 if (ct->proto.dccp.last_dir == !dir &&
 537                     ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
 538                     type == DCCP_PKT_RESPONSE) {
 539                         ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
 540                         ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
 541                         ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 542                         new_state = CT_DCCP_RESPOND;
 543                         break;
 544                 }
 545                 ct->proto.dccp.last_dir = dir;
 546                 ct->proto.dccp.last_pkt = type;
 547
 548                 spin_unlock_bh(&ct->lock);
 549                 nf_ct_l4proto_log_invalid(skb, ct, "%s", "invalid packet");
 550                 return NF_ACCEPT;
 551         case CT_DCCP_INVALID:
 552                 spin_unlock_bh(&ct->lock);
 553                 nf_ct_l4proto_log_invalid(skb, ct, "%s", "invalid state transition");
 554                 return -NF_ACCEPT;
 555         }
 556
 557         ct->proto.dccp.last_dir = dir;
 558         ct->proto.dccp.last_pkt = type;
 559         ct->proto.dccp.state = new_state;
 560         spin_unlock_bh(&ct->lock);
 561
 562         if (new_state != old_state)
 563                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
 564
 565         timeouts = nf_ct_timeout_lookup(ct);
 566         if (!timeouts)
 567                 timeouts = nf_dccp_pernet(nf_ct_net(ct))->dccp_timeout;
 568         nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);
 569
 570         return NF_ACCEPT;
 571 }
 572
 573 static bool dccp_can_early_drop(const struct nf_conn *ct)
 574 {
 575         switch (ct->proto.dccp.state) {
 576         case CT_DCCP_CLOSEREQ:
 577         case CT_DCCP_CLOSING:
 578         case CT_DCCP_TIMEWAIT:
 579                 return true;
 580         default:
 581                 break;
 582         }
 583
 584         return false;
 585 }
 586
 587 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 588 static void dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 589 {
 590         seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
 591 }
 592 #endif
 593
 594 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 595 static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
 596                           struct nf_conn *ct)
 597 {
 598         struct nlattr *nest_parms;
 599
 600         spin_lock_bh(&ct->lock);
 601         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
 602         if (!nest_parms)
 603                 goto nla_put_failure;
 604         if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state) ||
 605             nla_put_u8(skb, CTA_PROTOINFO_DCCP_ROLE,
 606                        ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]) ||
 607             nla_put_be64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ,
 608                          cpu_to_be64(ct->proto.dccp.handshake_seq),
 609                          CTA_PROTOINFO_DCCP_PAD))
 610                 goto nla_put_failure;
 611         nla_nest_end(skb, nest_parms);
 612         spin_unlock_bh(&ct->lock);
 613         return 0;
 614
 615 nla_put_failure:
 616         spin_unlock_bh(&ct->lock);
 617         return -1;
 618 }
 619
 620 static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
 621         [CTA_PROTOINFO_DCCP_STATE]      = { .type = NLA_U8 },
 622         [CTA_PROTOINFO_DCCP_ROLE]       = { .type = NLA_U8 },
 623         [CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 },
 624         [CTA_PROTOINFO_DCCP_PAD]        = { .type = NLA_UNSPEC },
 625 };
 626
 627 #define DCCP_NLATTR_SIZE ( \
 628         NLA_ALIGN(NLA_HDRLEN + 1) + \
 629         NLA_ALIGN(NLA_HDRLEN + 1) + \
 630         NLA_ALIGN(NLA_HDRLEN + sizeof(u64)) + \
 631         NLA_ALIGN(NLA_HDRLEN + 0))
 632
 633 static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
 634 {
 635         struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
 636         struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
 637         int err;
 638
 639         if (!attr)
 640                 return 0;
 641
 642         err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
 643                                dccp_nla_policy, NULL);
 644         if (err < 0)
 645                 return err;
 646
 647         if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
 648             !tb[CTA_PROTOINFO_DCCP_ROLE] ||
 649             nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX ||
 650             nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) {
 651                 return -EINVAL;
 652         }
 653
 654         spin_lock_bh(&ct->lock);
 655         ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
 656         if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) {
 657                 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 658                 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 659         } else {
 660                 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER;
 661                 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT;
 662         }
 663         if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) {
 664                 ct->proto.dccp.handshake_seq =
 665                 be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]));
 666         }
 667         spin_unlock_bh(&ct->lock);
 668         return 0;
 669 }
 670 #endif
 671
 672 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 673
 674 #include <linux/netfilter/nfnetlink.h>
 675 #include <linux/netfilter/nfnetlink_cttimeout.h>
 676
 677 static int dccp_timeout_nlattr_to_obj(struct nlattr *tb[],
 678                                       struct net *net, void *data)
 679 {
 680         struct nf_dccp_net *dn = nf_dccp_pernet(net);
 681         unsigned int *timeouts = data;
 682         int i;
 683
 684         /* set default DCCP timeouts. */
 685         for (i=0; i<CT_DCCP_MAX; i++)
 686                 timeouts[i] = dn->dccp_timeout[i];
 687
 688         /* there's a 1:1 mapping between attributes and protocol states. */
 689         for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 690                 if (tb[i]) {
 691                         timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ;
 692                 }
 693         }
 694
 695         timeouts[CTA_TIMEOUT_DCCP_UNSPEC] = timeouts[CTA_TIMEOUT_DCCP_REQUEST];
 696         return 0;
 697 }
 698
 699 static int
 700 dccp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 701 {
 702         const unsigned int *timeouts = data;
 703         int i;
 704
 705         for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 706                 if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ)))
 707                         goto nla_put_failure;
 708         }
 709         return 0;
 710
 711 nla_put_failure:
 712         return -ENOSPC;
 713 }
 714
 715 static const struct nla_policy
 716 dccp_timeout_nla_policy[CTA_TIMEOUT_DCCP_MAX+1] = {
 717         [CTA_TIMEOUT_DCCP_REQUEST]      = { .type = NLA_U32 },
 718         [CTA_TIMEOUT_DCCP_RESPOND]      = { .type = NLA_U32 },
 719         [CTA_TIMEOUT_DCCP_PARTOPEN]     = { .type = NLA_U32 },
 720         [CTA_TIMEOUT_DCCP_OPEN]         = { .type = NLA_U32 },
 721         [CTA_TIMEOUT_DCCP_CLOSEREQ]     = { .type = NLA_U32 },
 722         [CTA_TIMEOUT_DCCP_CLOSING]      = { .type = NLA_U32 },
 723         [CTA_TIMEOUT_DCCP_TIMEWAIT]     = { .type = NLA_U32 },
 724 };
 725 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 726
 727 #ifdef CONFIG_SYSCTL
 728 /* template, data assigned later */
 729 static struct ctl_table dccp_sysctl_table[] = {
 730         {
 731                 .procname       = "nf_conntrack_dccp_timeout_request",
 732                 .maxlen         = sizeof(unsigned int),
 733                 .mode           = 0644,
 734                 .proc_handler   = proc_dointvec_jiffies,
 735         },
 736         {
 737                 .procname       = "nf_conntrack_dccp_timeout_respond",
 738                 .maxlen         = sizeof(unsigned int),
 739                 .mode           = 0644,
 740                 .proc_handler   = proc_dointvec_jiffies,
 741         },
 742         {
 743                 .procname       = "nf_conntrack_dccp_timeout_partopen",
 744                 .maxlen         = sizeof(unsigned int),
 745                 .mode           = 0644,
 746                 .proc_handler   = proc_dointvec_jiffies,
 747         },
 748         {
 749                 .procname       = "nf_conntrack_dccp_timeout_open",
 750                 .maxlen         = sizeof(unsigned int),
 751                 .mode           = 0644,
 752                 .proc_handler   = proc_dointvec_jiffies,
 753         },
 754         {
 755                 .procname       = "nf_conntrack_dccp_timeout_closereq",
 756                 .maxlen         = sizeof(unsigned int),
 757                 .mode           = 0644,
 758                 .proc_handler   = proc_dointvec_jiffies,
 759         },
 760         {
 761                 .procname       = "nf_conntrack_dccp_timeout_closing",
 762                 .maxlen         = sizeof(unsigned int),
 763                 .mode           = 0644,
 764                 .proc_handler   = proc_dointvec_jiffies,
 765         },
 766         {
 767                 .procname       = "nf_conntrack_dccp_timeout_timewait",
 768                 .maxlen         = sizeof(unsigned int),
 769                 .mode           = 0644,
 770                 .proc_handler   = proc_dointvec_jiffies,
 771         },
 772         {
 773                 .procname       = "nf_conntrack_dccp_loose",
 774                 .maxlen         = sizeof(int),
 775                 .mode           = 0644,
 776                 .proc_handler   = proc_dointvec,
 777         },
 778         { }
 779 };
 780 #endif /* CONFIG_SYSCTL */
 781
 782 static int dccp_kmemdup_sysctl_table(struct net *net, struct nf_proto_net *pn,
 783                                      struct nf_dccp_net *dn)
 784 {
 785 #ifdef CONFIG_SYSCTL
 786         if (pn->ctl_table)
 787                 return 0;
 788
 789         pn->ctl_table = kmemdup(dccp_sysctl_table,
 790                                 sizeof(dccp_sysctl_table),
 791                                 GFP_KERNEL);
 792         if (!pn->ctl_table)
 793                 return -ENOMEM;
 794
 795         pn->ctl_table[0].data = &dn->dccp_timeout[CT_DCCP_REQUEST];
 796         pn->ctl_table[1].data = &dn->dccp_timeout[CT_DCCP_RESPOND];
 797         pn->ctl_table[2].data = &dn->dccp_timeout[CT_DCCP_PARTOPEN];
 798         pn->ctl_table[3].data = &dn->dccp_timeout[CT_DCCP_OPEN];
 799         pn->ctl_table[4].data = &dn->dccp_timeout[CT_DCCP_CLOSEREQ];
 800         pn->ctl_table[5].data = &dn->dccp_timeout[CT_DCCP_CLOSING];
 801         pn->ctl_table[6].data = &dn->dccp_timeout[CT_DCCP_TIMEWAIT];
 802         pn->ctl_table[7].data = &dn->dccp_loose;
 803
 804         /* Don't export sysctls to unprivileged users */
 805         if (net->user_ns != &init_user_ns)
 806                 pn->ctl_table[0].procname = NULL;
 807 #endif
 808         return 0;
 809 }
 810
 811 static int dccp_init_net(struct net *net)
 812 {
 813         struct nf_dccp_net *dn = nf_dccp_pernet(net);
 814         struct nf_proto_net *pn = &dn->pn;
 815
 816         if (!pn->users) {
 817                 /* default values */
 818                 dn->dccp_loose = 1;
 819                 dn->dccp_timeout[CT_DCCP_REQUEST]       = 2 * DCCP_MSL;
 820                 dn->dccp_timeout[CT_DCCP_RESPOND]       = 4 * DCCP_MSL;
 821                 dn->dccp_timeout[CT_DCCP_PARTOPEN]      = 4 * DCCP_MSL;
 822                 dn->dccp_timeout[CT_DCCP_OPEN]          = 12 * 3600 * HZ;
 823                 dn->dccp_timeout[CT_DCCP_CLOSEREQ]      = 64 * HZ;
 824                 dn->dccp_timeout[CT_DCCP_CLOSING]       = 64 * HZ;
 825                 dn->dccp_timeout[CT_DCCP_TIMEWAIT]      = 2 * DCCP_MSL;
 826
 827                 /* timeouts[0] is unused, make it same as SYN_SENT so
 828                  * ->timeouts[0] contains 'new' timeout, like udp or icmp.
 829                  */
 830                 dn->dccp_timeout[CT_DCCP_NONE] = dn->dccp_timeout[CT_DCCP_REQUEST];
 831         }
 832
 833         return dccp_kmemdup_sysctl_table(net, pn, dn);
 834 }
 835
 836 static struct nf_proto_net *dccp_get_net_proto(struct net *net)
 837 {
 838         return &net->ct.nf_ct_proto.dccp.pn;
 839 }
 840
 841 const struct nf_conntrack_l4proto nf_conntrack_l4proto_dccp = {
 842         .l4proto                = IPPROTO_DCCP,
 843         .can_early_drop         = dccp_can_early_drop,
 844 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 845         .print_conntrack        = dccp_print_conntrack,
 846 #endif
 847 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 848         .nlattr_size            = DCCP_NLATTR_SIZE,
 849         .to_nlattr              = dccp_to_nlattr,
 850         .from_nlattr            = nlattr_to_dccp,
 851         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 852         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 853         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 854         .nla_policy             = nf_ct_port_nla_policy,
 855 #endif
 856 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 857         .ctnl_timeout           = {
 858                 .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
 859                 .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
 860                 .nlattr_max     = CTA_TIMEOUT_DCCP_MAX,
 861                 .obj_size       = sizeof(unsigned int) * CT_DCCP_MAX,
 862                 .nla_policy     = dccp_timeout_nla_policy,
 863         },
 864 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 865         .init_net               = dccp_init_net,
 866         .get_net_proto          = dccp_get_net_proto,
 867 };