net/netfilter/nf_conntrack_proto_tcp.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>:
   9  *      - Real stateful connection tracking
  10  *      - Modified state transitions table
  11  *      - Window scaling support added
  12  *      - SACK support added
  13  *
  14  * Willy Tarreau:
  15  *      - State table bugfixes
  16  *      - More robust state changes
  17  *      - Tuning timer parameters
  18  *
  19  * 27 Oct 2004: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  20  *      - genelized Layer 3 protocol part.
  21  *
  22  * Derived from net/ipv4/netfilter/ip_conntrack_proto_tcp.c
  23  *
  24  * version 2.2
  25  */
  26
  27 #include <linux/types.h>
  28 #include <linux/sched.h>
  29 #include <linux/timer.h>
  30 #include <linux/netfilter.h>
  31 #include <linux/module.h>
  32 #include <linux/in.h>
  33 #include <linux/tcp.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/skbuff.h>
  36 #include <linux/ipv6.h>
  37 #include <net/ip6_checksum.h>
  38
  39 #include <net/tcp.h>
  40
  41 #include <linux/netfilter.h>
  42 #include <linux/netfilter_ipv4.h>
  43 #include <linux/netfilter_ipv6.h>
  44 #include <net/netfilter/nf_conntrack.h>
  45 #include <net/netfilter/nf_conntrack_l4proto.h>
  46 #include <net/netfilter/nf_conntrack_ecache.h>
  47
  48 #if 0
  49 #define DEBUGP printk
  50 #define DEBUGP_VARS
  51 #else
  52 #define DEBUGP(format, args...)
  53 #endif
  54
  55 /* Protects conntrack->proto.tcp */
  56 static DEFINE_RWLOCK(tcp_lock);
  57
  58 /* "Be conservative in what you do,
  59     be liberal in what you accept from others."
  60     If it's non-zero, we mark only out of window RST segments as INVALID. */
  61 int nf_ct_tcp_be_liberal __read_mostly = 0;
  62
  63 /* When connection is picked up from the middle, how many packets are required
  64    to pass in each direction when we assume we are in sync - if any side uses
  65    window scaling, we lost the game.
  66    If it is set to zero, we disable picking up already established
  67    connections. */
  68 int nf_ct_tcp_loose __read_mostly = 3;
  69
  70 /* Max number of the retransmitted packets without receiving an (acceptable)
  71    ACK from the destination. If this number is reached, a shorter timer
  72    will be started. */
  73 int nf_ct_tcp_max_retrans __read_mostly = 3;
  74
  75   /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
  76      closely.  They're more complex. --RR */
  77
  78 static const char *tcp_conntrack_names[] = {
  79         "NONE",
  80         "SYN_SENT",
  81         "SYN_RECV",
  82         "ESTABLISHED",
  83         "FIN_WAIT",
  84         "CLOSE_WAIT",
  85         "LAST_ACK",
  86         "TIME_WAIT",
  87         "CLOSE",
  88         "LISTEN"
  89 };
  90
  91 #define SECS * HZ
  92 #define MINS * 60 SECS
  93 #define HOURS * 60 MINS
  94 #define DAYS * 24 HOURS
  95
  96 static unsigned int nf_ct_tcp_timeout_syn_sent __read_mostly =      2 MINS;
  97 static unsigned int nf_ct_tcp_timeout_syn_recv __read_mostly =     60 SECS;
  98 static unsigned int nf_ct_tcp_timeout_established __read_mostly =   5 DAYS;
  99 static unsigned int nf_ct_tcp_timeout_fin_wait __read_mostly =      2 MINS;
 100 static unsigned int nf_ct_tcp_timeout_close_wait __read_mostly =   60 SECS;
 101 static unsigned int nf_ct_tcp_timeout_last_ack __read_mostly =     30 SECS;
 102 static unsigned int nf_ct_tcp_timeout_time_wait __read_mostly =     2 MINS;
 103 static unsigned int nf_ct_tcp_timeout_close __read_mostly =        10 SECS;
 104
 105 /* RFC1122 says the R2 limit should be at least 100 seconds.
 106    Linux uses 15 packets as limit, which corresponds
 107    to ~13-30min depending on RTO. */
 108 static unsigned int nf_ct_tcp_timeout_max_retrans __read_mostly =   5 MINS;
 109
 110 static unsigned int * tcp_timeouts[] = {
 111     NULL,                              /* TCP_CONNTRACK_NONE */
 112     &nf_ct_tcp_timeout_syn_sent,       /* TCP_CONNTRACK_SYN_SENT, */
 113     &nf_ct_tcp_timeout_syn_recv,       /* TCP_CONNTRACK_SYN_RECV, */
 114     &nf_ct_tcp_timeout_established,    /* TCP_CONNTRACK_ESTABLISHED, */
 115     &nf_ct_tcp_timeout_fin_wait,       /* TCP_CONNTRACK_FIN_WAIT, */
 116     &nf_ct_tcp_timeout_close_wait,     /* TCP_CONNTRACK_CLOSE_WAIT, */
 117     &nf_ct_tcp_timeout_last_ack,       /* TCP_CONNTRACK_LAST_ACK, */
 118     &nf_ct_tcp_timeout_time_wait,      /* TCP_CONNTRACK_TIME_WAIT, */
 119     &nf_ct_tcp_timeout_close,          /* TCP_CONNTRACK_CLOSE, */
 120     NULL,                              /* TCP_CONNTRACK_LISTEN */
 121  };
 122
 123 #define sNO TCP_CONNTRACK_NONE
 124 #define sSS TCP_CONNTRACK_SYN_SENT
 125 #define sSR TCP_CONNTRACK_SYN_RECV
 126 #define sES TCP_CONNTRACK_ESTABLISHED
 127 #define sFW TCP_CONNTRACK_FIN_WAIT
 128 #define sCW TCP_CONNTRACK_CLOSE_WAIT
 129 #define sLA TCP_CONNTRACK_LAST_ACK
 130 #define sTW TCP_CONNTRACK_TIME_WAIT
 131 #define sCL TCP_CONNTRACK_CLOSE
 132 #define sLI TCP_CONNTRACK_LISTEN
 133 #define sIV TCP_CONNTRACK_MAX
 134 #define sIG TCP_CONNTRACK_IGNORE
 135
 136 /* What TCP flags are set from RST/SYN/FIN/ACK. */
 137 enum tcp_bit_set {
 138         TCP_SYN_SET,
 139         TCP_SYNACK_SET,
 140         TCP_FIN_SET,
 141         TCP_ACK_SET,
 142         TCP_RST_SET,
 143         TCP_NONE_SET,
 144 };
 145
 146 /*
 147  * The TCP state transition table needs a few words...
 148  *
 149  * We are the man in the middle. All the packets go through us
 150  * but might get lost in transit to the destination.
 151  * It is assumed that the destinations can't receive segments
 152  * we haven't seen.
 153  *
 154  * The checked segment is in window, but our windows are *not*
 155  * equivalent with the ones of the sender/receiver. We always
 156  * try to guess the state of the current sender.
 157  *
 158  * The meaning of the states are:
 159  *
 160  * NONE:        initial state
 161  * SYN_SENT:    SYN-only packet seen
 162  * SYN_RECV:    SYN-ACK packet seen
 163  * ESTABLISHED: ACK packet seen
 164  * FIN_WAIT:    FIN packet seen
 165  * CLOSE_WAIT:  ACK seen (after FIN)
 166  * LAST_ACK:    FIN seen (after FIN)
 167  * TIME_WAIT:   last ACK seen
 168  * CLOSE:       closed connection
 169  *
 170  * LISTEN state is not used.
 171  *
 172  * Packets marked as IGNORED (sIG):
 173  *      if they may be either invalid or valid
 174  *      and the receiver may send back a connection
 175  *      closing RST or a SYN/ACK.
 176  *
 177  * Packets marked as INVALID (sIV):
 178  *      if they are invalid
 179  *      or we do not support the request (simultaneous open)
 180  */
 181 static enum tcp_conntrack tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
 182         {
 183 /* ORIGINAL */
 184 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 185 /*syn*/    { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sIV },
 186 /*
 187  *      sNO -> sSS      Initialize a new connection
 188  *      sSS -> sSS      Retransmitted SYN
 189  *      sSR -> sIG      Late retransmitted SYN?
 190  *      sES -> sIG      Error: SYNs in window outside the SYN_SENT state
 191  *                      are errors. Receiver will reply with RST
 192  *                      and close the connection.
 193  *                      Or we are not in sync and hold a dead connection.
 194  *      sFW -> sIG
 195  *      sCW -> sIG
 196  *      sLA -> sIG
 197  *      sTW -> sSS      Reopened connection (RFC 1122).
 198  *      sCL -> sSS
 199  */
 200 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 201 /*synack*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV },
 202 /*
 203  * A SYN/ACK from the client is always invalid:
 204  *      - either it tries to set up a simultaneous open, which is
 205  *        not supported;
 206  *      - or the firewall has just been inserted between the two hosts
 207  *        during the session set-up. The SYN will be retransmitted
 208  *        by the true client (or it'll time out).
 209  */
 210 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 211 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 212 /*
 213  *      sNO -> sIV      Too late and no reason to do anything...
 214  *      sSS -> sIV      Client migth not send FIN in this state:
 215  *                      we enforce waiting for a SYN/ACK reply first.
 216  *      sSR -> sFW      Close started.
 217  *      sES -> sFW
 218  *      sFW -> sLA      FIN seen in both directions, waiting for
 219  *                      the last ACK.
 220  *                      Migth be a retransmitted FIN as well...
 221  *      sCW -> sLA
 222  *      sLA -> sLA      Retransmitted FIN. Remain in the same state.
 223  *      sTW -> sTW
 224  *      sCL -> sCL
 225  */
 226 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 227 /*ack*/    { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 228 /*
 229  *      sNO -> sES      Assumed.
 230  *      sSS -> sIV      ACK is invalid: we haven't seen a SYN/ACK yet.
 231  *      sSR -> sES      Established state is reached.
 232  *      sES -> sES      :-)
 233  *      sFW -> sCW      Normal close request answered by ACK.
 234  *      sCW -> sCW
 235  *      sLA -> sTW      Last ACK detected.
 236  *      sTW -> sTW      Retransmitted last ACK. Remain in the same state.
 237  *      sCL -> sCL
 238  */
 239 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 240 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV },
 241 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 242         },
 243         {
 244 /* REPLY */
 245 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 246 /*syn*/    { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV },
 247 /*
 248  *      sNO -> sIV      Never reached.
 249  *      sSS -> sIV      Simultaneous open, not supported
 250  *      sSR -> sIV      Simultaneous open, not supported.
 251  *      sES -> sIV      Server may not initiate a connection.
 252  *      sFW -> sIV
 253  *      sCW -> sIV
 254  *      sLA -> sIV
 255  *      sTW -> sIV      Reopened connection, but server may not do it.
 256  *      sCL -> sIV
 257  */
 258 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 259 /*synack*/ { sIV, sSR, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIV },
 260 /*
 261  *      sSS -> sSR      Standard open.
 262  *      sSR -> sSR      Retransmitted SYN/ACK.
 263  *      sES -> sIG      Late retransmitted SYN/ACK?
 264  *      sFW -> sIG      Might be SYN/ACK answering ignored SYN
 265  *      sCW -> sIG
 266  *      sLA -> sIG
 267  *      sTW -> sIG
 268  *      sCL -> sIG
 269  */
 270 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 271 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 272 /*
 273  *      sSS -> sIV      Server might not send FIN in this state.
 274  *      sSR -> sFW      Close started.
 275  *      sES -> sFW
 276  *      sFW -> sLA      FIN seen in both directions.
 277  *      sCW -> sLA
 278  *      sLA -> sLA      Retransmitted FIN.
 279  *      sTW -> sTW
 280  *      sCL -> sCL
 281  */
 282 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 283 /*ack*/    { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 284 /*
 285  *      sSS -> sIG      Might be a half-open connection.
 286  *      sSR -> sSR      Might answer late resent SYN.
 287  *      sES -> sES      :-)
 288  *      sFW -> sCW      Normal close request answered by ACK.
 289  *      sCW -> sCW
 290  *      sLA -> sTW      Last ACK detected.
 291  *      sTW -> sTW      Retransmitted last ACK.
 292  *      sCL -> sCL
 293  */
 294 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 295 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV },
 296 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 297         }
 298 };
 299
 300 static int tcp_pkt_to_tuple(const struct sk_buff *skb,
 301                             unsigned int dataoff,
 302                             struct nf_conntrack_tuple *tuple)
 303 {
 304         struct tcphdr _hdr, *hp;
 305
 306         /* Actually only need first 8 bytes. */
 307         hp = skb_header_pointer(skb, dataoff, 8, &_hdr);
 308         if (hp == NULL)
 309                 return 0;
 310
 311         tuple->src.u.tcp.port = hp->source;
 312         tuple->dst.u.tcp.port = hp->dest;
 313
 314         return 1;
 315 }
 316
 317 static int tcp_invert_tuple(struct nf_conntrack_tuple *tuple,
 318                             const struct nf_conntrack_tuple *orig)
 319 {
 320         tuple->src.u.tcp.port = orig->dst.u.tcp.port;
 321         tuple->dst.u.tcp.port = orig->src.u.tcp.port;
 322         return 1;
 323 }
 324
 325 /* Print out the per-protocol part of the tuple. */
 326 static int tcp_print_tuple(struct seq_file *s,
 327                            const struct nf_conntrack_tuple *tuple)
 328 {
 329         return seq_printf(s, "sport=%hu dport=%hu ",
 330                           ntohs(tuple->src.u.tcp.port),
 331                           ntohs(tuple->dst.u.tcp.port));
 332 }
 333
 334 /* Print out the private part of the conntrack. */
 335 static int tcp_print_conntrack(struct seq_file *s,
 336                                const struct nf_conn *conntrack)
 337 {
 338         enum tcp_conntrack state;
 339
 340         read_lock_bh(&tcp_lock);
 341         state = conntrack->proto.tcp.state;
 342         read_unlock_bh(&tcp_lock);
 343
 344         return seq_printf(s, "%s ", tcp_conntrack_names[state]);
 345 }
 346
 347 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
 348 {
 349         if (tcph->rst) return TCP_RST_SET;
 350         else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
 351         else if (tcph->fin) return TCP_FIN_SET;
 352         else if (tcph->ack) return TCP_ACK_SET;
 353         else return TCP_NONE_SET;
 354 }
 355
 356 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
 357    in IP Filter' by Guido van Rooij.
 358
 359    http://www.nluug.nl/events/sane2000/papers.html
 360    http://www.iae.nl/users/guido/papers/tcp_filtering.ps.gz
 361
 362    The boundaries and the conditions are changed according to RFC793:
 363    the packet must intersect the window (i.e. segments may be
 364    after the right or before the left edge) and thus receivers may ACK
 365    segments after the right edge of the window.
 366
 367         td_maxend = max(sack + max(win,1)) seen in reply packets
 368         td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
 369         td_maxwin += seq + len - sender.td_maxend
 370                         if seq + len > sender.td_maxend
 371         td_end    = max(seq + len) seen in sent packets
 372
 373    I.   Upper bound for valid data:     seq <= sender.td_maxend
 374    II.  Lower bound for valid data:     seq + len >= sender.td_end - receiver.td_maxwin
 375    III. Upper bound for valid ack:      sack <= receiver.td_end
 376    IV.  Lower bound for valid ack:      ack >= receiver.td_end - MAXACKWINDOW
 377
 378    where sack is the highest right edge of sack block found in the packet.
 379
 380    The upper bound limit for a valid ack is not ignored -
 381    we doesn't have to deal with fragments.
 382 */
 383
 384 static inline __u32 segment_seq_plus_len(__u32 seq,
 385                                          size_t len,
 386                                          unsigned int dataoff,
 387                                          struct tcphdr *tcph)
 388 {
 389         /* XXX Should I use payload length field in IP/IPv6 header ?
 390          * - YK */
 391         return (seq + len - dataoff - tcph->doff*4
 392                 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
 393 }
 394
 395 /* Fixme: what about big packets? */
 396 #define MAXACKWINCONST                  66000
 397 #define MAXACKWINDOW(sender)                                            \
 398         ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin     \
 399                                               : MAXACKWINCONST)
 400
 401 /*
 402  * Simplified tcp_parse_options routine from tcp_input.c
 403  */
 404 static void tcp_options(const struct sk_buff *skb,
 405                         unsigned int dataoff,
 406                         struct tcphdr *tcph,
 407                         struct ip_ct_tcp_state *state)
 408 {
 409         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 410         unsigned char *ptr;
 411         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 412
 413         if (!length)
 414                 return;
 415
 416         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 417                                  length, buff);
 418         BUG_ON(ptr == NULL);
 419
 420         state->td_scale =
 421         state->flags = 0;
 422
 423         while (length > 0) {
 424                 int opcode=*ptr++;
 425                 int opsize;
 426
 427                 switch (opcode) {
 428                 case TCPOPT_EOL:
 429                         return;
 430                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 431                         length--;
 432                         continue;
 433                 default:
 434                         opsize=*ptr++;
 435                         if (opsize < 2) /* "silly options" */
 436                                 return;
 437                         if (opsize > length)
 438                                 break;  /* don't parse partial options */
 439
 440                         if (opcode == TCPOPT_SACK_PERM
 441                             && opsize == TCPOLEN_SACK_PERM)
 442                                 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
 443                         else if (opcode == TCPOPT_WINDOW
 444                                  && opsize == TCPOLEN_WINDOW) {
 445                                 state->td_scale = *(u_int8_t *)ptr;
 446
 447                                 if (state->td_scale > 14) {
 448                                         /* See RFC1323 */
 449                                         state->td_scale = 14;
 450                                 }
 451                                 state->flags |=
 452                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 453                         }
 454                         ptr += opsize - 2;
 455                         length -= opsize;
 456                 }
 457         }
 458 }
 459
 460 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
 461                      struct tcphdr *tcph, __u32 *sack)
 462 {
 463         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 464         unsigned char *ptr;
 465         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 466         __u32 tmp;
 467
 468         if (!length)
 469                 return;
 470
 471         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 472                                  length, buff);
 473         BUG_ON(ptr == NULL);
 474
 475         /* Fast path for timestamp-only option */
 476         if (length == TCPOLEN_TSTAMP_ALIGNED*4
 477             && *(__be32 *)ptr ==
 478                 __constant_htonl((TCPOPT_NOP << 24)
 479                                  | (TCPOPT_NOP << 16)
 480                                  | (TCPOPT_TIMESTAMP << 8)
 481                                  | TCPOLEN_TIMESTAMP))
 482                 return;
 483
 484         while (length > 0) {
 485                 int opcode = *ptr++;
 486                 int opsize, i;
 487
 488                 switch (opcode) {
 489                 case TCPOPT_EOL:
 490                         return;
 491                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 492                         length--;
 493                         continue;
 494                 default:
 495                         opsize = *ptr++;
 496                         if (opsize < 2) /* "silly options" */
 497                                 return;
 498                         if (opsize > length)
 499                                 break;  /* don't parse partial options */
 500
 501                         if (opcode == TCPOPT_SACK
 502                             && opsize >= (TCPOLEN_SACK_BASE
 503                                           + TCPOLEN_SACK_PERBLOCK)
 504                             && !((opsize - TCPOLEN_SACK_BASE)
 505                                  % TCPOLEN_SACK_PERBLOCK)) {
 506                                 for (i = 0;
 507                                      i < (opsize - TCPOLEN_SACK_BASE);
 508                                      i += TCPOLEN_SACK_PERBLOCK) {
 509                                         tmp = ntohl(*((__be32 *)(ptr+i)+1));
 510
 511                                         if (after(tmp, *sack))
 512                                                 *sack = tmp;
 513                                 }
 514                                 return;
 515                         }
 516                         ptr += opsize - 2;
 517                         length -= opsize;
 518                 }
 519         }
 520 }
 521
 522 static int tcp_in_window(struct ip_ct_tcp *state,
 523                          enum ip_conntrack_dir dir,
 524                          unsigned int index,
 525                          const struct sk_buff *skb,
 526                          unsigned int dataoff,
 527                          struct tcphdr *tcph,
 528                          int pf)
 529 {
 530         struct ip_ct_tcp_state *sender = &state->seen[dir];
 531         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 532         __u32 seq, ack, sack, end, win, swin;
 533         int res;
 534
 535         /*
 536          * Get the required data from the packet.
 537          */
 538         seq = ntohl(tcph->seq);
 539         ack = sack = ntohl(tcph->ack_seq);
 540         win = ntohs(tcph->window);
 541         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
 542
 543         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
 544                 tcp_sack(skb, dataoff, tcph, &sack);
 545
 546         DEBUGP("tcp_in_window: START\n");
 547         DEBUGP("tcp_in_window: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu "
 548                "seq=%u ack=%u sack=%u win=%u end=%u\n",
 549                 NIPQUAD(iph->saddr), ntohs(tcph->source),
 550                 NIPQUAD(iph->daddr), ntohs(tcph->dest),
 551                 seq, ack, sack, win, end);
 552         DEBUGP("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 553                "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 554                 sender->td_end, sender->td_maxend, sender->td_maxwin,
 555                 sender->td_scale,
 556                 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 557                 receiver->td_scale);
 558
 559         if (sender->td_end == 0) {
 560                 /*
 561                  * Initialize sender data.
 562                  */
 563                 if (tcph->syn && tcph->ack) {
 564                         /*
 565                          * Outgoing SYN-ACK in reply to a SYN.
 566                          */
 567                         sender->td_end =
 568                         sender->td_maxend = end;
 569                         sender->td_maxwin = (win == 0 ? 1 : win);
 570
 571                         tcp_options(skb, dataoff, tcph, sender);
 572                         /*
 573                          * RFC 1323:
 574                          * Both sides must send the Window Scale option
 575                          * to enable window scaling in either direction.
 576                          */
 577                         if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
 578                               && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
 579                                 sender->td_scale =
 580                                 receiver->td_scale = 0;
 581                 } else {
 582                         /*
 583                          * We are in the middle of a connection,
 584                          * its history is lost for us.
 585                          * Let's try to use the data from the packet.
 586                          */
 587                         sender->td_end = end;
 588                         sender->td_maxwin = (win == 0 ? 1 : win);
 589                         sender->td_maxend = end + sender->td_maxwin;
 590                 }
 591         } else if (((state->state == TCP_CONNTRACK_SYN_SENT
 592                      && dir == IP_CT_DIR_ORIGINAL)
 593                    || (state->state == TCP_CONNTRACK_SYN_RECV
 594                      && dir == IP_CT_DIR_REPLY))
 595                    && after(end, sender->td_end)) {
 596                 /*
 597                  * RFC 793: "if a TCP is reinitialized ... then it need
 598                  * not wait at all; it must only be sure to use sequence
 599                  * numbers larger than those recently used."
 600                  */
 601                 sender->td_end =
 602                 sender->td_maxend = end;
 603                 sender->td_maxwin = (win == 0 ? 1 : win);
 604
 605                 tcp_options(skb, dataoff, tcph, sender);
 606         }
 607
 608         if (!(tcph->ack)) {
 609                 /*
 610                  * If there is no ACK, just pretend it was set and OK.
 611                  */
 612                 ack = sack = receiver->td_end;
 613         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
 614                     (TCP_FLAG_ACK|TCP_FLAG_RST))
 615                    && (ack == 0)) {
 616                 /*
 617                  * Broken TCP stacks, that set ACK in RST packets as well
 618                  * with zero ack value.
 619                  */
 620                 ack = sack = receiver->td_end;
 621         }
 622
 623         if (seq == end
 624             && (!tcph->rst
 625                 || (seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)))
 626                 /*
 627                  * Packets contains no data: we assume it is valid
 628                  * and check the ack value only.
 629                  * However RST segments are always validated by their
 630                  * SEQ number, except when seq == 0 (reset sent answering
 631                  * SYN.
 632                  */
 633                 seq = end = sender->td_end;
 634
 635         DEBUGP("tcp_in_window: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu "
 636                "seq=%u ack=%u sack =%u win=%u end=%u\n",
 637                 NIPQUAD(iph->saddr), ntohs(tcph->source),
 638                 NIPQUAD(iph->daddr), ntohs(tcph->dest),
 639                 seq, ack, sack, win, end);
 640         DEBUGP("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 641                "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 642                 sender->td_end, sender->td_maxend, sender->td_maxwin,
 643                 sender->td_scale,
 644                 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 645                 receiver->td_scale);
 646
 647         DEBUGP("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
 648                 before(seq, sender->td_maxend + 1),
 649                 after(end, sender->td_end - receiver->td_maxwin - 1),
 650                 before(sack, receiver->td_end + 1),
 651                 after(ack, receiver->td_end - MAXACKWINDOW(sender)));
 652
 653         if (sender->loose || receiver->loose ||
 654             (before(seq, sender->td_maxend + 1) &&
 655              after(end, sender->td_end - receiver->td_maxwin - 1) &&
 656              before(sack, receiver->td_end + 1) &&
 657              after(ack, receiver->td_end - MAXACKWINDOW(sender)))) {
 658                 /*
 659                  * Take into account window scaling (RFC 1323).
 660                  */
 661                 if (!tcph->syn)
 662                         win <<= sender->td_scale;
 663
 664                 /*
 665                  * Update sender data.
 666                  */
 667                 swin = win + (sack - ack);
 668                 if (sender->td_maxwin < swin)
 669                         sender->td_maxwin = swin;
 670                 if (after(end, sender->td_end))
 671                         sender->td_end = end;
 672                 /*
 673                  * Update receiver data.
 674                  */
 675                 if (after(end, sender->td_maxend))
 676                         receiver->td_maxwin += end - sender->td_maxend;
 677                 if (after(sack + win, receiver->td_maxend - 1)) {
 678                         receiver->td_maxend = sack + win;
 679                         if (win == 0)
 680                                 receiver->td_maxend++;
 681                 }
 682
 683                 /*
 684                  * Check retransmissions.
 685                  */
 686                 if (index == TCP_ACK_SET) {
 687                         if (state->last_dir == dir
 688                             && state->last_seq == seq
 689                             && state->last_ack == ack
 690                             && state->last_end == end
 691                             && state->last_win == win)
 692                                 state->retrans++;
 693                         else {
 694                                 state->last_dir = dir;
 695                                 state->last_seq = seq;
 696                                 state->last_ack = ack;
 697                                 state->last_end = end;
 698                                 state->last_win = win;
 699                                 state->retrans = 0;
 700                         }
 701                 }
 702                 /*
 703                  * Close the window of disabled window tracking :-)
 704                  */
 705                 if (sender->loose)
 706                         sender->loose--;
 707
 708                 res = 1;
 709         } else {
 710                 if (LOG_INVALID(IPPROTO_TCP))
 711                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 712                         "nf_ct_tcp: %s ",
 713                         before(seq, sender->td_maxend + 1) ?
 714                         after(end, sender->td_end - receiver->td_maxwin - 1) ?
 715                         before(sack, receiver->td_end + 1) ?
 716                         after(ack, receiver->td_end - MAXACKWINDOW(sender)) ? "BUG"
 717                         : "ACK is under the lower bound (possible overly delayed ACK)"
 718                         : "ACK is over the upper bound (ACKed data not seen yet)"
 719                         : "SEQ is under the lower bound (already ACKed data retransmitted)"
 720                         : "SEQ is over the upper bound (over the window of the receiver)");
 721
 722                 res = nf_ct_tcp_be_liberal;
 723         }
 724
 725         DEBUGP("tcp_in_window: res=%i sender end=%u maxend=%u maxwin=%u "
 726                "receiver end=%u maxend=%u maxwin=%u\n",
 727                 res, sender->td_end, sender->td_maxend, sender->td_maxwin,
 728                 receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
 729
 730         return res;
 731 }
 732
 733 #ifdef CONFIG_NF_NAT_NEEDED
 734 /* Update sender->td_end after NAT successfully mangled the packet */
 735 /* Caller must linearize skb at tcp header. */
 736 void nf_conntrack_tcp_update(struct sk_buff *skb,
 737                              unsigned int dataoff,
 738                              struct nf_conn *conntrack,
 739                              int dir)
 740 {
 741         struct tcphdr *tcph = (void *)skb->data + dataoff;
 742         __u32 end;
 743 #ifdef DEBUGP_VARS
 744         struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[dir];
 745         struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[!dir];
 746 #endif
 747
 748         end = segment_seq_plus_len(ntohl(tcph->seq), skb->len, dataoff, tcph);
 749
 750         write_lock_bh(&tcp_lock);
 751         /*
 752          * We have to worry for the ack in the reply packet only...
 753          */
 754         if (after(end, conntrack->proto.tcp.seen[dir].td_end))
 755                 conntrack->proto.tcp.seen[dir].td_end = end;
 756         conntrack->proto.tcp.last_end = end;
 757         write_unlock_bh(&tcp_lock);
 758         DEBUGP("tcp_update: sender end=%u maxend=%u maxwin=%u scale=%i "
 759                "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 760                 sender->td_end, sender->td_maxend, sender->td_maxwin,
 761                 sender->td_scale,
 762                 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 763                 receiver->td_scale);
 764 }
 765 EXPORT_SYMBOL_GPL(nf_conntrack_tcp_update);
 766 #endif
 767
 768 #define TH_FIN  0x01
 769 #define TH_SYN  0x02
 770 #define TH_RST  0x04
 771 #define TH_PUSH 0x08
 772 #define TH_ACK  0x10
 773 #define TH_URG  0x20
 774 #define TH_ECE  0x40
 775 #define TH_CWR  0x80
 776
 777 /* table of valid flag combinations - ECE and CWR are always valid */
 778 static u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG) + 1] =
 779 {
 780         [TH_SYN]                        = 1,
 781         [TH_SYN|TH_PUSH]                = 1,
 782         [TH_SYN|TH_URG]                 = 1,
 783         [TH_SYN|TH_PUSH|TH_URG]         = 1,
 784         [TH_SYN|TH_ACK]                 = 1,
 785         [TH_SYN|TH_ACK|TH_PUSH]         = 1,
 786         [TH_RST]                        = 1,
 787         [TH_RST|TH_ACK]                 = 1,
 788         [TH_RST|TH_ACK|TH_PUSH]         = 1,
 789         [TH_FIN|TH_ACK]                 = 1,
 790         [TH_ACK]                        = 1,
 791         [TH_ACK|TH_PUSH]                = 1,
 792         [TH_ACK|TH_URG]                 = 1,
 793         [TH_ACK|TH_URG|TH_PUSH]         = 1,
 794         [TH_FIN|TH_ACK|TH_PUSH]         = 1,
 795         [TH_FIN|TH_ACK|TH_URG]          = 1,
 796         [TH_FIN|TH_ACK|TH_URG|TH_PUSH]  = 1,
 797 };
 798
 799 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
 800 static int tcp_error(struct sk_buff *skb,
 801                      unsigned int dataoff,
 802                      enum ip_conntrack_info *ctinfo,
 803                      int pf,
 804                      unsigned int hooknum)
 805 {
 806         struct tcphdr _tcph, *th;
 807         unsigned int tcplen = skb->len - dataoff;
 808         u_int8_t tcpflags;
 809
 810         /* Smaller that minimal TCP header? */
 811         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 812         if (th == NULL) {
 813                 if (LOG_INVALID(IPPROTO_TCP))
 814                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 815                                 "nf_ct_tcp: short packet ");
 816                 return -NF_ACCEPT;
 817         }
 818
 819         /* Not whole TCP header or malformed packet */
 820         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
 821                 if (LOG_INVALID(IPPROTO_TCP))
 822                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 823                                 "nf_ct_tcp: truncated/malformed packet ");
 824                 return -NF_ACCEPT;
 825         }
 826
 827         /* Checksum invalid? Ignore.
 828          * We skip checking packets on the outgoing path
 829          * because the checksum is assumed to be correct.
 830          */
 831         /* FIXME: Source route IP option packets --RR */
 832         if (nf_conntrack_checksum &&
 833             ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
 834              (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) &&
 835             nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
 836                 if (LOG_INVALID(IPPROTO_TCP))
 837                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 838                                   "nf_ct_tcp: bad TCP checksum ");
 839                 return -NF_ACCEPT;
 840         }
 841
 842         /* Check TCP flags. */
 843         tcpflags = (((u_int8_t *)th)[13] & ~(TH_ECE|TH_CWR));
 844         if (!tcp_valid_flags[tcpflags]) {
 845                 if (LOG_INVALID(IPPROTO_TCP))
 846                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 847                                   "nf_ct_tcp: invalid TCP flag combination ");
 848                 return -NF_ACCEPT;
 849         }
 850
 851         return NF_ACCEPT;
 852 }
 853
 854 /* Returns verdict for packet, or -1 for invalid. */
 855 static int tcp_packet(struct nf_conn *conntrack,
 856                       const struct sk_buff *skb,
 857                       unsigned int dataoff,
 858                       enum ip_conntrack_info ctinfo,
 859                       int pf,
 860                       unsigned int hooknum)
 861 {
 862         enum tcp_conntrack new_state, old_state;
 863         enum ip_conntrack_dir dir;
 864         struct tcphdr *th, _tcph;
 865         unsigned long timeout;
 866         unsigned int index;
 867
 868         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 869         BUG_ON(th == NULL);
 870
 871         write_lock_bh(&tcp_lock);
 872         old_state = conntrack->proto.tcp.state;
 873         dir = CTINFO2DIR(ctinfo);
 874         index = get_conntrack_index(th);
 875         new_state = tcp_conntracks[dir][index][old_state];
 876
 877         switch (new_state) {
 878         case TCP_CONNTRACK_IGNORE:
 879                 /* Ignored packets:
 880                  *
 881                  * a) SYN in ORIGINAL
 882                  * b) SYN/ACK in REPLY
 883                  * c) ACK in reply direction after initial SYN in original.
 884                  */
 885                 if (index == TCP_SYNACK_SET
 886                     && conntrack->proto.tcp.last_index == TCP_SYN_SET
 887                     && conntrack->proto.tcp.last_dir != dir
 888                     && ntohl(th->ack_seq) ==
 889                              conntrack->proto.tcp.last_end) {
 890                         /* This SYN/ACK acknowledges a SYN that we earlier
 891                          * ignored as invalid. This means that the client and
 892                          * the server are both in sync, while the firewall is
 893                          * not. We kill this session and block the SYN/ACK so
 894                          * that the client cannot but retransmit its SYN and
 895                          * thus initiate a clean new session.
 896                          */
 897                         write_unlock_bh(&tcp_lock);
 898                         if (LOG_INVALID(IPPROTO_TCP))
 899                                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 900                                           "nf_ct_tcp: killing out of sync session ");
 901                         if (del_timer(&conntrack->timeout))
 902                                 conntrack->timeout.function((unsigned long)
 903                                                             conntrack);
 904                         return -NF_DROP;
 905                 }
 906                 conntrack->proto.tcp.last_index = index;
 907                 conntrack->proto.tcp.last_dir = dir;
 908                 conntrack->proto.tcp.last_seq = ntohl(th->seq);
 909                 conntrack->proto.tcp.last_end =
 910                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
 911
 912                 write_unlock_bh(&tcp_lock);
 913                 if (LOG_INVALID(IPPROTO_TCP))
 914                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 915                                   "nf_ct_tcp: invalid packed ignored ");
 916                 return NF_ACCEPT;
 917         case TCP_CONNTRACK_MAX:
 918                 /* Invalid packet */
 919                 DEBUGP("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
 920                        dir, get_conntrack_index(th),
 921                        old_state);
 922                 write_unlock_bh(&tcp_lock);
 923                 if (LOG_INVALID(IPPROTO_TCP))
 924                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 925                                   "nf_ct_tcp: invalid state ");
 926                 return -NF_ACCEPT;
 927         case TCP_CONNTRACK_SYN_SENT:
 928                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 929                         break;
 930                 if ((conntrack->proto.tcp.seen[dir].flags &
 931                         IP_CT_TCP_FLAG_CLOSE_INIT)
 932                     || after(ntohl(th->seq),
 933                              conntrack->proto.tcp.seen[dir].td_end)) {
 934                         /* Attempt to reopen a closed connection.
 935                         * Delete this connection and look up again. */
 936                         write_unlock_bh(&tcp_lock);
 937                         if (del_timer(&conntrack->timeout))
 938                                 conntrack->timeout.function((unsigned long)
 939                                                             conntrack);
 940                         return -NF_REPEAT;
 941                 } else {
 942                         write_unlock_bh(&tcp_lock);
 943                         if (LOG_INVALID(IPPROTO_TCP))
 944                                 nf_log_packet(pf, 0, skb, NULL, NULL,
 945                                               NULL, "nf_ct_tcp: invalid SYN");
 946                         return -NF_ACCEPT;
 947                 }
 948         case TCP_CONNTRACK_CLOSE:
 949                 if (index == TCP_RST_SET
 950                     && ((test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)
 951                          && conntrack->proto.tcp.last_index == TCP_SYN_SET)
 952                         || (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
 953                             && conntrack->proto.tcp.last_index == TCP_ACK_SET))
 954                     && ntohl(th->ack_seq) == conntrack->proto.tcp.last_end) {
 955                         /* RST sent to invalid SYN or ACK we had let through
 956                          * at a) and c) above:
 957                          *
 958                          * a) SYN was in window then
 959                          * c) we hold a half-open connection.
 960                          *
 961                          * Delete our connection entry.
 962                          * We skip window checking, because packet might ACK
 963                          * segments we ignored. */
 964                         goto in_window;
 965                 }
 966                 /* Just fall through */
 967         default:
 968                 /* Keep compilers happy. */
 969                 break;
 970         }
 971
 972         if (!tcp_in_window(&conntrack->proto.tcp, dir, index,
 973                            skb, dataoff, th, pf)) {
 974                 write_unlock_bh(&tcp_lock);
 975                 return -NF_ACCEPT;
 976         }
 977      in_window:
 978         /* From now on we have got in-window packets */
 979         conntrack->proto.tcp.last_index = index;
 980
 981         DEBUGP("tcp_conntracks: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu "
 982                "syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
 983                 NIPQUAD(iph->saddr), ntohs(th->source),
 984                 NIPQUAD(iph->daddr), ntohs(th->dest),
 985                 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
 986                 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
 987                 old_state, new_state);
 988
 989         conntrack->proto.tcp.state = new_state;
 990         if (old_state != new_state
 991             && (new_state == TCP_CONNTRACK_FIN_WAIT
 992                 || new_state == TCP_CONNTRACK_CLOSE))
 993                 conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
 994         timeout = conntrack->proto.tcp.retrans >= nf_ct_tcp_max_retrans
 995                   && *tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans
 996                   ? nf_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state];
 997         write_unlock_bh(&tcp_lock);
 998
 999         nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
1000         if (new_state != old_state)
1001                 nf_conntrack_event_cache(IPCT_PROTOINFO, skb);
1002
1003         if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
1004                 /* If only reply is a RST, we can consider ourselves not to
1005                    have an established connection: this is a fairly common
1006                    problem case, so we can delete the conntrack
1007                    immediately.  --RR */
1008                 if (th->rst) {
1009                         if (del_timer(&conntrack->timeout))
1010                                 conntrack->timeout.function((unsigned long)
1011                                                             conntrack);
1012                         return NF_ACCEPT;
1013                 }
1014         } else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
1015                    && (old_state == TCP_CONNTRACK_SYN_RECV
1016                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1017                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1018                 /* Set ASSURED if we see see valid ack in ESTABLISHED
1019                    after SYN_RECV or a valid answer for a picked up
1020                    connection. */
1021                 set_bit(IPS_ASSURED_BIT, &conntrack->status);
1022                 nf_conntrack_event_cache(IPCT_STATUS, skb);
1023         }
1024         nf_ct_refresh_acct(conntrack, ctinfo, skb, timeout);
1025
1026         return NF_ACCEPT;
1027 }
1028
1029 /* Called when a new connection for this protocol found. */
1030 static int tcp_new(struct nf_conn *conntrack,
1031                    const struct sk_buff *skb,
1032                    unsigned int dataoff)
1033 {
1034         enum tcp_conntrack new_state;
1035         struct tcphdr *th, _tcph;
1036 #ifdef DEBUGP_VARS
1037         struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[0];
1038         struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[1];
1039 #endif
1040
1041         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
1042         BUG_ON(th == NULL);
1043
1044         /* Don't need lock here: this conntrack not in circulation yet */
1045         new_state
1046                 = tcp_conntracks[0][get_conntrack_index(th)]
1047                 [TCP_CONNTRACK_NONE];
1048
1049         /* Invalid: delete conntrack */
1050         if (new_state >= TCP_CONNTRACK_MAX) {
1051                 DEBUGP("nf_ct_tcp: invalid new deleting.\n");
1052                 return 0;
1053         }
1054
1055         if (new_state == TCP_CONNTRACK_SYN_SENT) {
1056                 /* SYN packet */
1057                 conntrack->proto.tcp.seen[0].td_end =
1058                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1059                                              dataoff, th);
1060                 conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1061                 if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
1062                         conntrack->proto.tcp.seen[0].td_maxwin = 1;
1063                 conntrack->proto.tcp.seen[0].td_maxend =
1064                         conntrack->proto.tcp.seen[0].td_end;
1065
1066                 tcp_options(skb, dataoff, th, &conntrack->proto.tcp.seen[0]);
1067                 conntrack->proto.tcp.seen[1].flags = 0;
1068                 conntrack->proto.tcp.seen[0].loose =
1069                 conntrack->proto.tcp.seen[1].loose = 0;
1070         } else if (nf_ct_tcp_loose == 0) {
1071                 /* Don't try to pick up connections. */
1072                 return 0;
1073         } else {
1074                 /*
1075                  * We are in the middle of a connection,
1076                  * its history is lost for us.
1077                  * Let's try to use the data from the packet.
1078                  */
1079                 conntrack->proto.tcp.seen[0].td_end =
1080                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1081                                              dataoff, th);
1082                 conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1083                 if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
1084                         conntrack->proto.tcp.seen[0].td_maxwin = 1;
1085                 conntrack->proto.tcp.seen[0].td_maxend =
1086                         conntrack->proto.tcp.seen[0].td_end +
1087                         conntrack->proto.tcp.seen[0].td_maxwin;
1088                 conntrack->proto.tcp.seen[0].td_scale = 0;
1089
1090                 /* We assume SACK. Should we assume window scaling too? */
1091                 conntrack->proto.tcp.seen[0].flags =
1092                 conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM;
1093                 conntrack->proto.tcp.seen[0].loose =
1094                 conntrack->proto.tcp.seen[1].loose = nf_ct_tcp_loose;
1095         }
1096
1097         conntrack->proto.tcp.seen[1].td_end = 0;
1098         conntrack->proto.tcp.seen[1].td_maxend = 0;
1099         conntrack->proto.tcp.seen[1].td_maxwin = 1;
1100         conntrack->proto.tcp.seen[1].td_scale = 0;
1101
1102         /* tcp_packet will set them */
1103         conntrack->proto.tcp.state = TCP_CONNTRACK_NONE;
1104         conntrack->proto.tcp.last_index = TCP_NONE_SET;
1105
1106         DEBUGP("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
1107                "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
1108                 sender->td_end, sender->td_maxend, sender->td_maxwin,
1109                 sender->td_scale,
1110                 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
1111                 receiver->td_scale);
1112         return 1;
1113 }
1114
1115 #if defined(CONFIG_NF_CT_NETLINK) || \
1116     defined(CONFIG_NF_CT_NETLINK_MODULE)
1117
1118 #include <linux/netfilter/nfnetlink.h>
1119 #include <linux/netfilter/nfnetlink_conntrack.h>
1120
1121 static int tcp_to_nfattr(struct sk_buff *skb, struct nfattr *nfa,
1122                          const struct nf_conn *ct)
1123 {
1124         struct nfattr *nest_parms;
1125
1126         read_lock_bh(&tcp_lock);
1127         nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
1128         NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t),
1129                 &ct->proto.tcp.state);
1130         read_unlock_bh(&tcp_lock);
1131
1132         NFA_NEST_END(skb, nest_parms);
1133
1134         return 0;
1135
1136 nfattr_failure:
1137         read_unlock_bh(&tcp_lock);
1138         return -1;
1139 }
1140
1141 static const size_t cta_min_tcp[CTA_PROTOINFO_TCP_MAX] = {
1142         [CTA_PROTOINFO_TCP_STATE-1]     = sizeof(u_int8_t),
1143 };
1144
1145 static int nfattr_to_tcp(struct nfattr *cda[], struct nf_conn *ct)
1146 {
1147         struct nfattr *attr = cda[CTA_PROTOINFO_TCP-1];
1148         struct nfattr *tb[CTA_PROTOINFO_TCP_MAX];
1149
1150         /* updates could not contain anything about the private
1151          * protocol info, in that case skip the parsing */
1152         if (!attr)
1153                 return 0;
1154
1155         nfattr_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, attr);
1156
1157         if (nfattr_bad_size(tb, CTA_PROTOINFO_TCP_MAX, cta_min_tcp))
1158                 return -EINVAL;
1159
1160         if (!tb[CTA_PROTOINFO_TCP_STATE-1])
1161                 return -EINVAL;
1162
1163         write_lock_bh(&tcp_lock);
1164         ct->proto.tcp.state =
1165                 *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_STATE-1]);
1166         write_unlock_bh(&tcp_lock);
1167
1168         return 0;
1169 }
1170 #endif
1171
1172 #ifdef CONFIG_SYSCTL
1173 static unsigned int tcp_sysctl_table_users;
1174 static struct ctl_table_header *tcp_sysctl_header;
1175 static struct ctl_table tcp_sysctl_table[] = {
1176         {
1177                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_SYN_SENT,
1178                 .procname       = "nf_conntrack_tcp_timeout_syn_sent",
1179                 .data           = &nf_ct_tcp_timeout_syn_sent,
1180                 .maxlen         = sizeof(unsigned int),
1181                 .mode           = 0644,
1182                 .proc_handler   = &proc_dointvec_jiffies,
1183         },
1184         {
1185                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_SYN_RECV,
1186                 .procname       = "nf_conntrack_tcp_timeout_syn_recv",
1187                 .data           = &nf_ct_tcp_timeout_syn_recv,
1188                 .maxlen         = sizeof(unsigned int),
1189                 .mode           = 0644,
1190                 .proc_handler   = &proc_dointvec_jiffies,
1191         },
1192         {
1193                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_ESTABLISHED,
1194                 .procname       = "nf_conntrack_tcp_timeout_established",
1195                 .data           = &nf_ct_tcp_timeout_established,
1196                 .maxlen         = sizeof(unsigned int),
1197                 .mode           = 0644,
1198                 .proc_handler   = &proc_dointvec_jiffies,
1199         },
1200         {
1201                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_FIN_WAIT,
1202                 .procname       = "nf_conntrack_tcp_timeout_fin_wait",
1203                 .data           = &nf_ct_tcp_timeout_fin_wait,
1204                 .maxlen         = sizeof(unsigned int),
1205                 .mode           = 0644,
1206                 .proc_handler   = &proc_dointvec_jiffies,
1207         },
1208         {
1209                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_CLOSE_WAIT,
1210                 .procname       = "nf_conntrack_tcp_timeout_close_wait",
1211                 .data           = &nf_ct_tcp_timeout_close_wait,
1212                 .maxlen         = sizeof(unsigned int),
1213                 .mode           = 0644,
1214                 .proc_handler   = &proc_dointvec_jiffies,
1215         },
1216         {
1217                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_LAST_ACK,
1218                 .procname       = "nf_conntrack_tcp_timeout_last_ack",
1219                 .data           = &nf_ct_tcp_timeout_last_ack,
1220                 .maxlen         = sizeof(unsigned int),
1221                 .mode           = 0644,
1222                 .proc_handler   = &proc_dointvec_jiffies,
1223         },
1224         {
1225                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_TIME_WAIT,
1226                 .procname       = "nf_conntrack_tcp_timeout_time_wait",
1227                 .data           = &nf_ct_tcp_timeout_time_wait,
1228                 .maxlen         = sizeof(unsigned int),
1229                 .mode           = 0644,
1230                 .proc_handler   = &proc_dointvec_jiffies,
1231         },
1232         {
1233                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_CLOSE,
1234                 .procname       = "nf_conntrack_tcp_timeout_close",
1235                 .data           = &nf_ct_tcp_timeout_close,
1236                 .maxlen         = sizeof(unsigned int),
1237                 .mode           = 0644,
1238                 .proc_handler   = &proc_dointvec_jiffies,
1239         },
1240         {
1241                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_MAX_RETRANS,
1242                 .procname       = "nf_conntrack_tcp_timeout_max_retrans",
1243                 .data           = &nf_ct_tcp_timeout_max_retrans,
1244                 .maxlen         = sizeof(unsigned int),
1245                 .mode           = 0644,
1246                 .proc_handler   = &proc_dointvec_jiffies,
1247         },
1248         {
1249                 .ctl_name       = NET_NF_CONNTRACK_TCP_LOOSE,
1250                 .procname       = "nf_conntrack_tcp_loose",
1251                 .data           = &nf_ct_tcp_loose,
1252                 .maxlen         = sizeof(unsigned int),
1253                 .mode           = 0644,
1254                 .proc_handler   = &proc_dointvec,
1255         },
1256         {
1257                 .ctl_name       = NET_NF_CONNTRACK_TCP_BE_LIBERAL,
1258                 .procname       = "nf_conntrack_tcp_be_liberal",
1259                 .data           = &nf_ct_tcp_be_liberal,
1260                 .maxlen         = sizeof(unsigned int),
1261                 .mode           = 0644,
1262                 .proc_handler   = &proc_dointvec,
1263         },
1264         {
1265                 .ctl_name       = NET_NF_CONNTRACK_TCP_MAX_RETRANS,
1266                 .procname       = "nf_conntrack_tcp_max_retrans",
1267                 .data           = &nf_ct_tcp_max_retrans,
1268                 .maxlen         = sizeof(unsigned int),
1269                 .mode           = 0644,
1270                 .proc_handler   = &proc_dointvec,
1271         },
1272         {
1273                 .ctl_name       = 0
1274         }
1275 };
1276
1277 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1278 static struct ctl_table tcp_compat_sysctl_table[] = {
1279         {
1280                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_SYN_SENT,
1281                 .procname       = "ip_conntrack_tcp_timeout_syn_sent",
1282                 .data           = &nf_ct_tcp_timeout_syn_sent,
1283                 .maxlen         = sizeof(unsigned int),
1284                 .mode           = 0644,
1285                 .proc_handler   = &proc_dointvec_jiffies,
1286         },
1287         {
1288                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_SYN_RECV,
1289                 .procname       = "ip_conntrack_tcp_timeout_syn_recv",
1290                 .data           = &nf_ct_tcp_timeout_syn_recv,
1291                 .maxlen         = sizeof(unsigned int),
1292                 .mode           = 0644,
1293                 .proc_handler   = &proc_dointvec_jiffies,
1294         },
1295         {
1296                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_ESTABLISHED,
1297                 .procname       = "ip_conntrack_tcp_timeout_established",
1298                 .data           = &nf_ct_tcp_timeout_established,
1299                 .maxlen         = sizeof(unsigned int),
1300                 .mode           = 0644,
1301                 .proc_handler   = &proc_dointvec_jiffies,
1302         },
1303         {
1304                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_FIN_WAIT,
1305                 .procname       = "ip_conntrack_tcp_timeout_fin_wait",
1306                 .data           = &nf_ct_tcp_timeout_fin_wait,
1307                 .maxlen         = sizeof(unsigned int),
1308                 .mode           = 0644,
1309                 .proc_handler   = &proc_dointvec_jiffies,
1310         },
1311         {
1312                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_CLOSE_WAIT,
1313                 .procname       = "ip_conntrack_tcp_timeout_close_wait",
1314                 .data           = &nf_ct_tcp_timeout_close_wait,
1315                 .maxlen         = sizeof(unsigned int),
1316                 .mode           = 0644,
1317                 .proc_handler   = &proc_dointvec_jiffies,
1318         },
1319         {
1320                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_LAST_ACK,
1321                 .procname       = "ip_conntrack_tcp_timeout_last_ack",
1322                 .data           = &nf_ct_tcp_timeout_last_ack,
1323                 .maxlen         = sizeof(unsigned int),
1324                 .mode           = 0644,
1325                 .proc_handler   = &proc_dointvec_jiffies,
1326         },
1327         {
1328                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_TIME_WAIT,
1329                 .procname       = "ip_conntrack_tcp_timeout_time_wait",
1330                 .data           = &nf_ct_tcp_timeout_time_wait,
1331                 .maxlen         = sizeof(unsigned int),
1332                 .mode           = 0644,
1333                 .proc_handler   = &proc_dointvec_jiffies,
1334         },
1335         {
1336                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_CLOSE,
1337                 .procname       = "ip_conntrack_tcp_timeout_close",
1338                 .data           = &nf_ct_tcp_timeout_close,
1339                 .maxlen         = sizeof(unsigned int),
1340                 .mode           = 0644,
1341                 .proc_handler   = &proc_dointvec_jiffies,
1342         },
1343         {
1344                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_MAX_RETRANS,
1345                 .procname       = "ip_conntrack_tcp_timeout_max_retrans",
1346                 .data           = &nf_ct_tcp_timeout_max_retrans,
1347                 .maxlen         = sizeof(unsigned int),
1348                 .mode           = 0644,
1349                 .proc_handler   = &proc_dointvec_jiffies,
1350         },
1351         {
1352                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_LOOSE,
1353                 .procname       = "ip_conntrack_tcp_loose",
1354                 .data           = &nf_ct_tcp_loose,
1355                 .maxlen         = sizeof(unsigned int),
1356                 .mode           = 0644,
1357                 .proc_handler   = &proc_dointvec,
1358         },
1359         {
1360                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_BE_LIBERAL,
1361                 .procname       = "ip_conntrack_tcp_be_liberal",
1362                 .data           = &nf_ct_tcp_be_liberal,
1363                 .maxlen         = sizeof(unsigned int),
1364                 .mode           = 0644,
1365                 .proc_handler   = &proc_dointvec,
1366         },
1367         {
1368                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_MAX_RETRANS,
1369                 .procname       = "ip_conntrack_tcp_max_retrans",
1370                 .data           = &nf_ct_tcp_max_retrans,
1371                 .maxlen         = sizeof(unsigned int),
1372                 .mode           = 0644,
1373                 .proc_handler   = &proc_dointvec,
1374         },
1375         {
1376                 .ctl_name       = 0
1377         }
1378 };
1379 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
1380 #endif /* CONFIG_SYSCTL */
1381
1382 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 =
1383 {
1384         .l3proto                = PF_INET,
1385         .l4proto                = IPPROTO_TCP,
1386         .name                   = "tcp",
1387         .pkt_to_tuple           = tcp_pkt_to_tuple,
1388         .invert_tuple           = tcp_invert_tuple,
1389         .print_tuple            = tcp_print_tuple,
1390         .print_conntrack        = tcp_print_conntrack,
1391         .packet                 = tcp_packet,
1392         .new                    = tcp_new,
1393         .error                  = tcp_error,
1394 #if defined(CONFIG_NF_CT_NETLINK) || \
1395     defined(CONFIG_NF_CT_NETLINK_MODULE)
1396         .to_nfattr              = tcp_to_nfattr,
1397         .from_nfattr            = nfattr_to_tcp,
1398         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
1399         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
1400 #endif
1401 #ifdef CONFIG_SYSCTL
1402         .ctl_table_users        = &tcp_sysctl_table_users,
1403         .ctl_table_header       = &tcp_sysctl_header,
1404         .ctl_table              = tcp_sysctl_table,
1405 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1406         .ctl_compat_table       = tcp_compat_sysctl_table,
1407 #endif
1408 #endif
1409 };
1410 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp4);
1411
1412 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp6 =
1413 {
1414         .l3proto                = PF_INET6,
1415         .l4proto                = IPPROTO_TCP,
1416         .name                   = "tcp",
1417         .pkt_to_tuple           = tcp_pkt_to_tuple,
1418         .invert_tuple           = tcp_invert_tuple,
1419         .print_tuple            = tcp_print_tuple,
1420         .print_conntrack        = tcp_print_conntrack,
1421         .packet                 = tcp_packet,
1422         .new                    = tcp_new,
1423         .error                  = tcp_error,
1424 #if defined(CONFIG_NF_CT_NETLINK) || \
1425     defined(CONFIG_NF_CT_NETLINK_MODULE)
1426         .to_nfattr              = tcp_to_nfattr,
1427         .from_nfattr            = nfattr_to_tcp,
1428         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
1429         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
1430 #endif
1431 #ifdef CONFIG_SYSCTL
1432         .ctl_table_users        = &tcp_sysctl_table_users,
1433         .ctl_table_header       = &tcp_sysctl_header,
1434         .ctl_table              = tcp_sysctl_table,
1435 #endif
1436 };
1437 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp6);