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