linux/net/netfilter/nf_conntrack_proto_dccp.c
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   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
  76static 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 */
 132static const u_int8_t
 133dccp_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 */
 388static int dccp_net_id __read_mostly;
 389struct dccp_net {
 390        struct nf_proto_net pn;
 391        int dccp_loose;
 392        unsigned int dccp_timeout[CT_DCCP_MAX + 1];
 393};
 394
 395static inline struct dccp_net *dccp_pernet(struct net *net)
 396{
 397        return net_generic(net, dccp_net_id);
 398}
 399
 400static bool dccp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
 401                              struct nf_conntrack_tuple *tuple)
 402{
 403        struct dccp_hdr _hdr, *dh;
 404
 405        dh = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 406        if (dh == NULL)
 407                return false;
 408
 409        tuple->src.u.dccp.port = dh->dccph_sport;
 410        tuple->dst.u.dccp.port = dh->dccph_dport;
 411        return true;
 412}
 413
 414static bool dccp_invert_tuple(struct nf_conntrack_tuple *inv,
 415                              const struct nf_conntrack_tuple *tuple)
 416{
 417        inv->src.u.dccp.port = tuple->dst.u.dccp.port;
 418        inv->dst.u.dccp.port = tuple->src.u.dccp.port;
 419        return true;
 420}
 421
 422static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
 423                     unsigned int dataoff, unsigned int *timeouts)
 424{
 425        struct net *net = nf_ct_net(ct);
 426        struct dccp_net *dn;
 427        struct dccp_hdr _dh, *dh;
 428        const char *msg;
 429        u_int8_t state;
 430
 431        dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 432        BUG_ON(dh == NULL);
 433
 434        state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
 435        switch (state) {
 436        default:
 437                dn = dccp_pernet(net);
 438                if (dn->dccp_loose == 0) {
 439                        msg = "nf_ct_dccp: not picking up existing connection ";
 440                        goto out_invalid;
 441                }
 442        case CT_DCCP_REQUEST:
 443                break;
 444        case CT_DCCP_INVALID:
 445                msg = "nf_ct_dccp: invalid state transition ";
 446                goto out_invalid;
 447        }
 448
 449        ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 450        ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 451        ct->proto.dccp.state = CT_DCCP_NONE;
 452        ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST;
 453        ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL;
 454        ct->proto.dccp.handshake_seq = 0;
 455        return true;
 456
 457out_invalid:
 458        if (LOG_INVALID(net, IPPROTO_DCCP))
 459                nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL, msg);
 460        return false;
 461}
 462
 463static u64 dccp_ack_seq(const struct dccp_hdr *dh)
 464{
 465        const struct dccp_hdr_ack_bits *dhack;
 466
 467        dhack = (void *)dh + __dccp_basic_hdr_len(dh);
 468        return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
 469                     ntohl(dhack->dccph_ack_nr_low);
 470}
 471
 472static unsigned int *dccp_get_timeouts(struct net *net)
 473{
 474        return dccp_pernet(net)->dccp_timeout;
 475}
 476
 477static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
 478                       unsigned int dataoff, enum ip_conntrack_info ctinfo,
 479                       u_int8_t pf, unsigned int hooknum,
 480                       unsigned int *timeouts)
 481{
 482        struct net *net = nf_ct_net(ct);
 483        enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 484        struct dccp_hdr _dh, *dh;
 485        u_int8_t type, old_state, new_state;
 486        enum ct_dccp_roles role;
 487
 488        dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 489        BUG_ON(dh == NULL);
 490        type = dh->dccph_type;
 491
 492        if (type == DCCP_PKT_RESET &&
 493            !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 494                /* Tear down connection immediately if only reply is a RESET */
 495                nf_ct_kill_acct(ct, ctinfo, skb);
 496                return NF_ACCEPT;
 497        }
 498
 499        spin_lock_bh(&ct->lock);
 500
 501        role = ct->proto.dccp.role[dir];
 502        old_state = ct->proto.dccp.state;
 503        new_state = dccp_state_table[role][type][old_state];
 504
 505        switch (new_state) {
 506        case CT_DCCP_REQUEST:
 507                if (old_state == CT_DCCP_TIMEWAIT &&
 508                    role == CT_DCCP_ROLE_SERVER) {
 509                        /* Reincarnation in the reverse direction: reopen and
 510                         * reverse client/server roles. */
 511                        ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
 512                        ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
 513                }
 514                break;
 515        case CT_DCCP_RESPOND:
 516                if (old_state == CT_DCCP_REQUEST)
 517                        ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 518                break;
 519        case CT_DCCP_PARTOPEN:
 520                if (old_state == CT_DCCP_RESPOND &&
 521                    type == DCCP_PKT_ACK &&
 522                    dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
 523                        set_bit(IPS_ASSURED_BIT, &ct->status);
 524                break;
 525        case CT_DCCP_IGNORE:
 526                /*
 527                 * Connection tracking might be out of sync, so we ignore
 528                 * packets that might establish a new connection and resync
 529                 * if the server responds with a valid Response.
 530                 */
 531                if (ct->proto.dccp.last_dir == !dir &&
 532                    ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
 533                    type == DCCP_PKT_RESPONSE) {
 534                        ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
 535                        ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
 536                        ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
 537                        new_state = CT_DCCP_RESPOND;
 538                        break;
 539                }
 540                ct->proto.dccp.last_dir = dir;
 541                ct->proto.dccp.last_pkt = type;
 542
 543                spin_unlock_bh(&ct->lock);
 544                if (LOG_INVALID(net, IPPROTO_DCCP))
 545                        nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 546                                      "nf_ct_dccp: invalid packet ignored ");
 547                return NF_ACCEPT;
 548        case CT_DCCP_INVALID:
 549                spin_unlock_bh(&ct->lock);
 550                if (LOG_INVALID(net, IPPROTO_DCCP))
 551                        nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 552                                      "nf_ct_dccp: invalid state transition ");
 553                return -NF_ACCEPT;
 554        }
 555
 556        ct->proto.dccp.last_dir = dir;
 557        ct->proto.dccp.last_pkt = type;
 558        ct->proto.dccp.state = new_state;
 559        spin_unlock_bh(&ct->lock);
 560
 561        if (new_state != old_state)
 562                nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
 563
 564        nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);
 565
 566        return NF_ACCEPT;
 567}
 568
 569static int dccp_error(struct net *net, struct nf_conn *tmpl,
 570                      struct sk_buff *skb, unsigned int dataoff,
 571                      enum ip_conntrack_info *ctinfo,
 572                      u_int8_t pf, unsigned int hooknum)
 573{
 574        struct dccp_hdr _dh, *dh;
 575        unsigned int dccp_len = skb->len - dataoff;
 576        unsigned int cscov;
 577        const char *msg;
 578
 579        dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
 580        if (dh == NULL) {
 581                msg = "nf_ct_dccp: short packet ";
 582                goto out_invalid;
 583        }
 584
 585        if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
 586            dh->dccph_doff * 4 > dccp_len) {
 587                msg = "nf_ct_dccp: truncated/malformed packet ";
 588                goto out_invalid;
 589        }
 590
 591        cscov = dccp_len;
 592        if (dh->dccph_cscov) {
 593                cscov = (dh->dccph_cscov - 1) * 4;
 594                if (cscov > dccp_len) {
 595                        msg = "nf_ct_dccp: bad checksum coverage ";
 596                        goto out_invalid;
 597                }
 598        }
 599
 600        if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 601            nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_DCCP,
 602                                pf)) {
 603                msg = "nf_ct_dccp: bad checksum ";
 604                goto out_invalid;
 605        }
 606
 607        if (dh->dccph_type >= DCCP_PKT_INVALID) {
 608                msg = "nf_ct_dccp: reserved packet type ";
 609                goto out_invalid;
 610        }
 611
 612        return NF_ACCEPT;
 613
 614out_invalid:
 615        if (LOG_INVALID(net, IPPROTO_DCCP))
 616                nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
 617        return -NF_ACCEPT;
 618}
 619
 620static int dccp_print_tuple(struct seq_file *s,
 621                            const struct nf_conntrack_tuple *tuple)
 622{
 623        return seq_printf(s, "sport=%hu dport=%hu ",
 624                          ntohs(tuple->src.u.dccp.port),
 625                          ntohs(tuple->dst.u.dccp.port));
 626}
 627
 628static int dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 629{
 630        return seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
 631}
 632
 633#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 634static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
 635                          struct nf_conn *ct)
 636{
 637        struct nlattr *nest_parms;
 638
 639        spin_lock_bh(&ct->lock);
 640        nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
 641        if (!nest_parms)
 642                goto nla_put_failure;
 643        if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state) ||
 644            nla_put_u8(skb, CTA_PROTOINFO_DCCP_ROLE,
 645                       ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]) ||
 646            nla_put_be64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ,
 647                         cpu_to_be64(ct->proto.dccp.handshake_seq)))
 648                goto nla_put_failure;
 649        nla_nest_end(skb, nest_parms);
 650        spin_unlock_bh(&ct->lock);
 651        return 0;
 652
 653nla_put_failure:
 654        spin_unlock_bh(&ct->lock);
 655        return -1;
 656}
 657
 658static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
 659        [CTA_PROTOINFO_DCCP_STATE]      = { .type = NLA_U8 },
 660        [CTA_PROTOINFO_DCCP_ROLE]       = { .type = NLA_U8 },
 661        [CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 },
 662};
 663
 664static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
 665{
 666        struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
 667        struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
 668        int err;
 669
 670        if (!attr)
 671                return 0;
 672
 673        err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
 674                               dccp_nla_policy);
 675        if (err < 0)
 676                return err;
 677
 678        if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
 679            !tb[CTA_PROTOINFO_DCCP_ROLE] ||
 680            nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX ||
 681            nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) {
 682                return -EINVAL;
 683        }
 684
 685        spin_lock_bh(&ct->lock);
 686        ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
 687        if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) {
 688                ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
 689                ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
 690        } else {
 691                ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER;
 692                ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT;
 693        }
 694        if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) {
 695                ct->proto.dccp.handshake_seq =
 696                be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]));
 697        }
 698        spin_unlock_bh(&ct->lock);
 699        return 0;
 700}
 701
 702static int dccp_nlattr_size(void)
 703{
 704        return nla_total_size(0)        /* CTA_PROTOINFO_DCCP */
 705                + nla_policy_len(dccp_nla_policy, CTA_PROTOINFO_DCCP_MAX + 1);
 706}
 707
 708#endif
 709
 710#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 711
 712#include <linux/netfilter/nfnetlink.h>
 713#include <linux/netfilter/nfnetlink_cttimeout.h>
 714
 715static int dccp_timeout_nlattr_to_obj(struct nlattr *tb[],
 716                                      struct net *net, void *data)
 717{
 718        struct dccp_net *dn = dccp_pernet(net);
 719        unsigned int *timeouts = data;
 720        int i;
 721
 722        /* set default DCCP timeouts. */
 723        for (i=0; i<CT_DCCP_MAX; i++)
 724                timeouts[i] = dn->dccp_timeout[i];
 725
 726        /* there's a 1:1 mapping between attributes and protocol states. */
 727        for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 728                if (tb[i]) {
 729                        timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ;
 730                }
 731        }
 732        return 0;
 733}
 734
 735static int
 736dccp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 737{
 738        const unsigned int *timeouts = data;
 739        int i;
 740
 741        for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
 742                if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ)))
 743                        goto nla_put_failure;
 744        }
 745        return 0;
 746
 747nla_put_failure:
 748        return -ENOSPC;
 749}
 750
 751static const struct nla_policy
 752dccp_timeout_nla_policy[CTA_TIMEOUT_DCCP_MAX+1] = {
 753        [CTA_TIMEOUT_DCCP_REQUEST]      = { .type = NLA_U32 },
 754        [CTA_TIMEOUT_DCCP_RESPOND]      = { .type = NLA_U32 },
 755        [CTA_TIMEOUT_DCCP_PARTOPEN]     = { .type = NLA_U32 },
 756        [CTA_TIMEOUT_DCCP_OPEN]         = { .type = NLA_U32 },
 757        [CTA_TIMEOUT_DCCP_CLOSEREQ]     = { .type = NLA_U32 },
 758        [CTA_TIMEOUT_DCCP_CLOSING]      = { .type = NLA_U32 },
 759        [CTA_TIMEOUT_DCCP_TIMEWAIT]     = { .type = NLA_U32 },
 760};
 761#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 762
 763#ifdef CONFIG_SYSCTL
 764/* template, data assigned later */
 765static struct ctl_table dccp_sysctl_table[] = {
 766        {
 767                .procname       = "nf_conntrack_dccp_timeout_request",
 768                .maxlen         = sizeof(unsigned int),
 769                .mode           = 0644,
 770                .proc_handler   = proc_dointvec_jiffies,
 771        },
 772        {
 773                .procname       = "nf_conntrack_dccp_timeout_respond",
 774                .maxlen         = sizeof(unsigned int),
 775                .mode           = 0644,
 776                .proc_handler   = proc_dointvec_jiffies,
 777        },
 778        {
 779                .procname       = "nf_conntrack_dccp_timeout_partopen",
 780                .maxlen         = sizeof(unsigned int),
 781                .mode           = 0644,
 782                .proc_handler   = proc_dointvec_jiffies,
 783        },
 784        {
 785                .procname       = "nf_conntrack_dccp_timeout_open",
 786                .maxlen         = sizeof(unsigned int),
 787                .mode           = 0644,
 788                .proc_handler   = proc_dointvec_jiffies,
 789        },
 790        {
 791                .procname       = "nf_conntrack_dccp_timeout_closereq",
 792                .maxlen         = sizeof(unsigned int),
 793                .mode           = 0644,
 794                .proc_handler   = proc_dointvec_jiffies,
 795        },
 796        {
 797                .procname       = "nf_conntrack_dccp_timeout_closing",
 798                .maxlen         = sizeof(unsigned int),
 799                .mode           = 0644,
 800                .proc_handler   = proc_dointvec_jiffies,
 801        },
 802        {
 803                .procname       = "nf_conntrack_dccp_timeout_timewait",
 804                .maxlen         = sizeof(unsigned int),
 805                .mode           = 0644,
 806                .proc_handler   = proc_dointvec_jiffies,
 807        },
 808        {
 809                .procname       = "nf_conntrack_dccp_loose",
 810                .maxlen         = sizeof(int),
 811                .mode           = 0644,
 812                .proc_handler   = proc_dointvec,
 813        },
 814        { }
 815};
 816#endif /* CONFIG_SYSCTL */
 817
 818static int dccp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 819                                     struct dccp_net *dn)
 820{
 821#ifdef CONFIG_SYSCTL
 822        if (pn->ctl_table)
 823                return 0;
 824
 825        pn->ctl_table = kmemdup(dccp_sysctl_table,
 826                                sizeof(dccp_sysctl_table),
 827                                GFP_KERNEL);
 828        if (!pn->ctl_table)
 829                return -ENOMEM;
 830
 831        pn->ctl_table[0].data = &dn->dccp_timeout[CT_DCCP_REQUEST];
 832        pn->ctl_table[1].data = &dn->dccp_timeout[CT_DCCP_RESPOND];
 833        pn->ctl_table[2].data = &dn->dccp_timeout[CT_DCCP_PARTOPEN];
 834        pn->ctl_table[3].data = &dn->dccp_timeout[CT_DCCP_OPEN];
 835        pn->ctl_table[4].data = &dn->dccp_timeout[CT_DCCP_CLOSEREQ];
 836        pn->ctl_table[5].data = &dn->dccp_timeout[CT_DCCP_CLOSING];
 837        pn->ctl_table[6].data = &dn->dccp_timeout[CT_DCCP_TIMEWAIT];
 838        pn->ctl_table[7].data = &dn->dccp_loose;
 839#endif
 840        return 0;
 841}
 842
 843static int dccp_init_net(struct net *net, u_int16_t proto)
 844{
 845        struct dccp_net *dn = dccp_pernet(net);
 846        struct nf_proto_net *pn = &dn->pn;
 847
 848        if (!pn->users) {
 849                /* default values */
 850                dn->dccp_loose = 1;
 851                dn->dccp_timeout[CT_DCCP_REQUEST]       = 2 * DCCP_MSL;
 852                dn->dccp_timeout[CT_DCCP_RESPOND]       = 4 * DCCP_MSL;
 853                dn->dccp_timeout[CT_DCCP_PARTOPEN]      = 4 * DCCP_MSL;
 854                dn->dccp_timeout[CT_DCCP_OPEN]          = 12 * 3600 * HZ;
 855                dn->dccp_timeout[CT_DCCP_CLOSEREQ]      = 64 * HZ;
 856                dn->dccp_timeout[CT_DCCP_CLOSING]       = 64 * HZ;
 857                dn->dccp_timeout[CT_DCCP_TIMEWAIT]      = 2 * DCCP_MSL;
 858        }
 859
 860        return dccp_kmemdup_sysctl_table(pn, dn);
 861}
 862
 863static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
 864        .l3proto                = AF_INET,
 865        .l4proto                = IPPROTO_DCCP,
 866        .name                   = "dccp",
 867        .pkt_to_tuple           = dccp_pkt_to_tuple,
 868        .invert_tuple           = dccp_invert_tuple,
 869        .new                    = dccp_new,
 870        .packet                 = dccp_packet,
 871        .get_timeouts           = dccp_get_timeouts,
 872        .error                  = dccp_error,
 873        .print_tuple            = dccp_print_tuple,
 874        .print_conntrack        = dccp_print_conntrack,
 875#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 876        .to_nlattr              = dccp_to_nlattr,
 877        .nlattr_size            = dccp_nlattr_size,
 878        .from_nlattr            = nlattr_to_dccp,
 879        .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 880        .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 881        .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 882        .nla_policy             = nf_ct_port_nla_policy,
 883#endif
 884#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 885        .ctnl_timeout           = {
 886                .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
 887                .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
 888                .nlattr_max     = CTA_TIMEOUT_DCCP_MAX,
 889                .obj_size       = sizeof(unsigned int) * CT_DCCP_MAX,
 890                .nla_policy     = dccp_timeout_nla_policy,
 891        },
 892#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 893        .net_id                 = &dccp_net_id,
 894        .init_net               = dccp_init_net,
 895};
 896
 897static struct nf_conntrack_l4proto dccp_proto6 __read_mostly = {
 898        .l3proto                = AF_INET6,
 899        .l4proto                = IPPROTO_DCCP,
 900        .name                   = "dccp",
 901        .pkt_to_tuple           = dccp_pkt_to_tuple,
 902        .invert_tuple           = dccp_invert_tuple,
 903        .new                    = dccp_new,
 904        .packet                 = dccp_packet,
 905        .get_timeouts           = dccp_get_timeouts,
 906        .error                  = dccp_error,
 907        .print_tuple            = dccp_print_tuple,
 908        .print_conntrack        = dccp_print_conntrack,
 909#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 910        .to_nlattr              = dccp_to_nlattr,
 911        .nlattr_size            = dccp_nlattr_size,
 912        .from_nlattr            = nlattr_to_dccp,
 913        .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 914        .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 915        .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 916        .nla_policy             = nf_ct_port_nla_policy,
 917#endif
 918#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 919        .ctnl_timeout           = {
 920                .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
 921                .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
 922                .nlattr_max     = CTA_TIMEOUT_DCCP_MAX,
 923                .obj_size       = sizeof(unsigned int) * CT_DCCP_MAX,
 924                .nla_policy     = dccp_timeout_nla_policy,
 925        },
 926#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 927        .net_id                 = &dccp_net_id,
 928        .init_net               = dccp_init_net,
 929};
 930
 931static __net_init int dccp_net_init(struct net *net)
 932{
 933        int ret = 0;
 934        ret = nf_conntrack_l4proto_register(net,
 935                                            &dccp_proto4);
 936        if (ret < 0) {
 937                pr_err("nf_conntrack_l4proto_dccp4 :protocol register failed.\n");
 938                goto out;
 939        }
 940        ret = nf_conntrack_l4proto_register(net,
 941                                            &dccp_proto6);
 942        if (ret < 0) {
 943                pr_err("nf_conntrack_l4proto_dccp6 :protocol register failed.\n");
 944                goto cleanup_dccp4;
 945        }
 946        return 0;
 947cleanup_dccp4:
 948        nf_conntrack_l4proto_unregister(net,
 949                                        &dccp_proto4);
 950out:
 951        return ret;
 952}
 953
 954static __net_exit void dccp_net_exit(struct net *net)
 955{
 956        nf_conntrack_l4proto_unregister(net,
 957                                        &dccp_proto6);
 958        nf_conntrack_l4proto_unregister(net,
 959                                        &dccp_proto4);
 960}
 961
 962static struct pernet_operations dccp_net_ops = {
 963        .init = dccp_net_init,
 964        .exit = dccp_net_exit,
 965        .id   = &dccp_net_id,
 966        .size = sizeof(struct dccp_net),
 967};
 968
 969static int __init nf_conntrack_proto_dccp_init(void)
 970{
 971        return register_pernet_subsys(&dccp_net_ops);
 972}
 973
 974static void __exit nf_conntrack_proto_dccp_fini(void)
 975{
 976        unregister_pernet_subsys(&dccp_net_ops);
 977}
 978
 979module_init(nf_conntrack_proto_dccp_init);
 980module_exit(nf_conntrack_proto_dccp_fini);
 981
 982MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 983MODULE_DESCRIPTION("DCCP connection tracking protocol helper");
 984MODULE_LICENSE("GPL");
 985
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