err.no Git - linux-2.6/blob - 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
   9 #include <linux/types.h>
  10 #include <linux/timer.h>
  11 #include <linux/module.h>
  12 #include <linux/in.h>
  13 #include <linux/tcp.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/ipv6.h>
  17 #include <net/ip6_checksum.h>
  18
  19 #include <net/tcp.h>
  20
  21 #include <linux/netfilter.h>
  22 #include <linux/netfilter_ipv4.h>
  23 #include <linux/netfilter_ipv6.h>
  24 #include <net/netfilter/nf_conntrack.h>
  25 #include <net/netfilter/nf_conntrack_l4proto.h>
  26 #include <net/netfilter/nf_conntrack_ecache.h>
  27 #include <net/netfilter/nf_log.h>
  28
  29 /* Protects conntrack->proto.tcp */
  30 static DEFINE_RWLOCK(tcp_lock);
  31
  32 /* "Be conservative in what you do,
  33     be liberal in what you accept from others."
  34     If it's non-zero, we mark only out of window RST segments as INVALID. */
  35 static int nf_ct_tcp_be_liberal __read_mostly = 0;
  36
  37 /* If it is set to zero, we disable picking up already established
  38    connections. */
  39 static int nf_ct_tcp_loose __read_mostly = 1;
  40
  41 /* Max number of the retransmitted packets without receiving an (acceptable)
  42    ACK from the destination. If this number is reached, a shorter timer
  43    will be started. */
  44 static int nf_ct_tcp_max_retrans __read_mostly = 3;
  45
  46   /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
  47      closely.  They're more complex. --RR */
  48
  49 static const char *tcp_conntrack_names[] = {
  50         "NONE",
  51         "SYN_SENT",
  52         "SYN_RECV",
  53         "ESTABLISHED",
  54         "FIN_WAIT",
  55         "CLOSE_WAIT",
  56         "LAST_ACK",
  57         "TIME_WAIT",
  58         "CLOSE",
  59         "LISTEN"
  60 };
  61
  62 #define SECS * HZ
  63 #define MINS * 60 SECS
  64 #define HOURS * 60 MINS
  65 #define DAYS * 24 HOURS
  66
  67 static unsigned int nf_ct_tcp_timeout_syn_sent __read_mostly =      2 MINS;
  68 static unsigned int nf_ct_tcp_timeout_syn_recv __read_mostly =     60 SECS;
  69 static unsigned int nf_ct_tcp_timeout_established __read_mostly =   5 DAYS;
  70 static unsigned int nf_ct_tcp_timeout_fin_wait __read_mostly =      2 MINS;
  71 static unsigned int nf_ct_tcp_timeout_close_wait __read_mostly =   60 SECS;
  72 static unsigned int nf_ct_tcp_timeout_last_ack __read_mostly =     30 SECS;
  73 static unsigned int nf_ct_tcp_timeout_time_wait __read_mostly =     2 MINS;
  74 static unsigned int nf_ct_tcp_timeout_close __read_mostly =        10 SECS;
  75
  76 /* RFC1122 says the R2 limit should be at least 100 seconds.
  77    Linux uses 15 packets as limit, which corresponds
  78    to ~13-30min depending on RTO. */
  79 static unsigned int nf_ct_tcp_timeout_max_retrans __read_mostly =   5 MINS;
  80
  81 static unsigned int * tcp_timeouts[] = {
  82     NULL,                              /* TCP_CONNTRACK_NONE */
  83     &nf_ct_tcp_timeout_syn_sent,       /* TCP_CONNTRACK_SYN_SENT, */
  84     &nf_ct_tcp_timeout_syn_recv,       /* TCP_CONNTRACK_SYN_RECV, */
  85     &nf_ct_tcp_timeout_established,    /* TCP_CONNTRACK_ESTABLISHED, */
  86     &nf_ct_tcp_timeout_fin_wait,       /* TCP_CONNTRACK_FIN_WAIT, */
  87     &nf_ct_tcp_timeout_close_wait,     /* TCP_CONNTRACK_CLOSE_WAIT, */
  88     &nf_ct_tcp_timeout_last_ack,       /* TCP_CONNTRACK_LAST_ACK, */
  89     &nf_ct_tcp_timeout_time_wait,      /* TCP_CONNTRACK_TIME_WAIT, */
  90     &nf_ct_tcp_timeout_close,          /* TCP_CONNTRACK_CLOSE, */
  91     NULL,                              /* TCP_CONNTRACK_LISTEN */
  92  };
  93
  94 #define sNO TCP_CONNTRACK_NONE
  95 #define sSS TCP_CONNTRACK_SYN_SENT
  96 #define sSR TCP_CONNTRACK_SYN_RECV
  97 #define sES TCP_CONNTRACK_ESTABLISHED
  98 #define sFW TCP_CONNTRACK_FIN_WAIT
  99 #define sCW TCP_CONNTRACK_CLOSE_WAIT
 100 #define sLA TCP_CONNTRACK_LAST_ACK
 101 #define sTW TCP_CONNTRACK_TIME_WAIT
 102 #define sCL TCP_CONNTRACK_CLOSE
 103 #define sLI TCP_CONNTRACK_LISTEN
 104 #define sIV TCP_CONNTRACK_MAX
 105 #define sIG TCP_CONNTRACK_IGNORE
 106
 107 /* What TCP flags are set from RST/SYN/FIN/ACK. */
 108 enum tcp_bit_set {
 109         TCP_SYN_SET,
 110         TCP_SYNACK_SET,
 111         TCP_FIN_SET,
 112         TCP_ACK_SET,
 113         TCP_RST_SET,
 114         TCP_NONE_SET,
 115 };
 116
 117 /*
 118  * The TCP state transition table needs a few words...
 119  *
 120  * We are the man in the middle. All the packets go through us
 121  * but might get lost in transit to the destination.
 122  * It is assumed that the destinations can't receive segments
 123  * we haven't seen.
 124  *
 125  * The checked segment is in window, but our windows are *not*
 126  * equivalent with the ones of the sender/receiver. We always
 127  * try to guess the state of the current sender.
 128  *
 129  * The meaning of the states are:
 130  *
 131  * NONE:        initial state
 132  * SYN_SENT:    SYN-only packet seen
 133  * SYN_RECV:    SYN-ACK packet seen
 134  * ESTABLISHED: ACK packet seen
 135  * FIN_WAIT:    FIN packet seen
 136  * CLOSE_WAIT:  ACK seen (after FIN)
 137  * LAST_ACK:    FIN seen (after FIN)
 138  * TIME_WAIT:   last ACK seen
 139  * CLOSE:       closed connection
 140  *
 141  * LISTEN state is not used.
 142  *
 143  * Packets marked as IGNORED (sIG):
 144  *      if they may be either invalid or valid
 145  *      and the receiver may send back a connection
 146  *      closing RST or a SYN/ACK.
 147  *
 148  * Packets marked as INVALID (sIV):
 149  *      if they are invalid
 150  *      or we do not support the request (simultaneous open)
 151  */
 152 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
 153         {
 154 /* ORIGINAL */
 155 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 156 /*syn*/    { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sIV },
 157 /*
 158  *      sNO -> sSS      Initialize a new connection
 159  *      sSS -> sSS      Retransmitted SYN
 160  *      sSR -> sIG      Late retransmitted SYN?
 161  *      sES -> sIG      Error: SYNs in window outside the SYN_SENT state
 162  *                      are errors. Receiver will reply with RST
 163  *                      and close the connection.
 164  *                      Or we are not in sync and hold a dead connection.
 165  *      sFW -> sIG
 166  *      sCW -> sIG
 167  *      sLA -> sIG
 168  *      sTW -> sSS      Reopened connection (RFC 1122).
 169  *      sCL -> sSS
 170  */
 171 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 172 /*synack*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV },
 173 /*
 174  * A SYN/ACK from the client is always invalid:
 175  *      - either it tries to set up a simultaneous open, which is
 176  *        not supported;
 177  *      - or the firewall has just been inserted between the two hosts
 178  *        during the session set-up. The SYN will be retransmitted
 179  *        by the true client (or it'll time out).
 180  */
 181 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 182 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 183 /*
 184  *      sNO -> sIV      Too late and no reason to do anything...
 185  *      sSS -> sIV      Client migth not send FIN in this state:
 186  *                      we enforce waiting for a SYN/ACK reply first.
 187  *      sSR -> sFW      Close started.
 188  *      sES -> sFW
 189  *      sFW -> sLA      FIN seen in both directions, waiting for
 190  *                      the last ACK.
 191  *                      Migth be a retransmitted FIN as well...
 192  *      sCW -> sLA
 193  *      sLA -> sLA      Retransmitted FIN. Remain in the same state.
 194  *      sTW -> sTW
 195  *      sCL -> sCL
 196  */
 197 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 198 /*ack*/    { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 199 /*
 200  *      sNO -> sES      Assumed.
 201  *      sSS -> sIV      ACK is invalid: we haven't seen a SYN/ACK yet.
 202  *      sSR -> sES      Established state is reached.
 203  *      sES -> sES      :-)
 204  *      sFW -> sCW      Normal close request answered by ACK.
 205  *      sCW -> sCW
 206  *      sLA -> sTW      Last ACK detected.
 207  *      sTW -> sTW      Retransmitted last ACK. Remain in the same state.
 208  *      sCL -> sCL
 209  */
 210 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 211 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV },
 212 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 213         },
 214         {
 215 /* REPLY */
 216 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 217 /*syn*/    { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV },
 218 /*
 219  *      sNO -> sIV      Never reached.
 220  *      sSS -> sIV      Simultaneous open, not supported
 221  *      sSR -> sIV      Simultaneous open, not supported.
 222  *      sES -> sIV      Server may not initiate a connection.
 223  *      sFW -> sIV
 224  *      sCW -> sIV
 225  *      sLA -> sIV
 226  *      sTW -> sIV      Reopened connection, but server may not do it.
 227  *      sCL -> sIV
 228  */
 229 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 230 /*synack*/ { sIV, sSR, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIV },
 231 /*
 232  *      sSS -> sSR      Standard open.
 233  *      sSR -> sSR      Retransmitted SYN/ACK.
 234  *      sES -> sIG      Late retransmitted SYN/ACK?
 235  *      sFW -> sIG      Might be SYN/ACK answering ignored SYN
 236  *      sCW -> sIG
 237  *      sLA -> sIG
 238  *      sTW -> sIG
 239  *      sCL -> sIG
 240  */
 241 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 242 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 243 /*
 244  *      sSS -> sIV      Server might not send FIN in this state.
 245  *      sSR -> sFW      Close started.
 246  *      sES -> sFW
 247  *      sFW -> sLA      FIN seen in both directions.
 248  *      sCW -> sLA
 249  *      sLA -> sLA      Retransmitted FIN.
 250  *      sTW -> sTW
 251  *      sCL -> sCL
 252  */
 253 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 254 /*ack*/    { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 255 /*
 256  *      sSS -> sIG      Might be a half-open connection.
 257  *      sSR -> sSR      Might answer late resent SYN.
 258  *      sES -> sES      :-)
 259  *      sFW -> sCW      Normal close request answered by ACK.
 260  *      sCW -> sCW
 261  *      sLA -> sTW      Last ACK detected.
 262  *      sTW -> sTW      Retransmitted last ACK.
 263  *      sCL -> sCL
 264  */
 265 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI   */
 266 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV },
 267 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 268         }
 269 };
 270
 271 static int tcp_pkt_to_tuple(const struct sk_buff *skb,
 272                             unsigned int dataoff,
 273                             struct nf_conntrack_tuple *tuple)
 274 {
 275         struct tcphdr _hdr, *hp;
 276
 277         /* Actually only need first 8 bytes. */
 278         hp = skb_header_pointer(skb, dataoff, 8, &_hdr);
 279         if (hp == NULL)
 280                 return 0;
 281
 282         tuple->src.u.tcp.port = hp->source;
 283         tuple->dst.u.tcp.port = hp->dest;
 284
 285         return 1;
 286 }
 287
 288 static int tcp_invert_tuple(struct nf_conntrack_tuple *tuple,
 289                             const struct nf_conntrack_tuple *orig)
 290 {
 291         tuple->src.u.tcp.port = orig->dst.u.tcp.port;
 292         tuple->dst.u.tcp.port = orig->src.u.tcp.port;
 293         return 1;
 294 }
 295
 296 /* Print out the per-protocol part of the tuple. */
 297 static int tcp_print_tuple(struct seq_file *s,
 298                            const struct nf_conntrack_tuple *tuple)
 299 {
 300         return seq_printf(s, "sport=%hu dport=%hu ",
 301                           ntohs(tuple->src.u.tcp.port),
 302                           ntohs(tuple->dst.u.tcp.port));
 303 }
 304
 305 /* Print out the private part of the conntrack. */
 306 static int tcp_print_conntrack(struct seq_file *s,
 307                                const struct nf_conn *conntrack)
 308 {
 309         enum tcp_conntrack state;
 310
 311         read_lock_bh(&tcp_lock);
 312         state = conntrack->proto.tcp.state;
 313         read_unlock_bh(&tcp_lock);
 314
 315         return seq_printf(s, "%s ", tcp_conntrack_names[state]);
 316 }
 317
 318 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
 319 {
 320         if (tcph->rst) return TCP_RST_SET;
 321         else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
 322         else if (tcph->fin) return TCP_FIN_SET;
 323         else if (tcph->ack) return TCP_ACK_SET;
 324         else return TCP_NONE_SET;
 325 }
 326
 327 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
 328    in IP Filter' by Guido van Rooij.
 329
 330    http://www.nluug.nl/events/sane2000/papers.html
 331    http://www.iae.nl/users/guido/papers/tcp_filtering.ps.gz
 332
 333    The boundaries and the conditions are changed according to RFC793:
 334    the packet must intersect the window (i.e. segments may be
 335    after the right or before the left edge) and thus receivers may ACK
 336    segments after the right edge of the window.
 337
 338         td_maxend = max(sack + max(win,1)) seen in reply packets
 339         td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
 340         td_maxwin += seq + len - sender.td_maxend
 341                         if seq + len > sender.td_maxend
 342         td_end    = max(seq + len) seen in sent packets
 343
 344    I.   Upper bound for valid data:     seq <= sender.td_maxend
 345    II.  Lower bound for valid data:     seq + len >= sender.td_end - receiver.td_maxwin
 346    III. Upper bound for valid ack:      sack <= receiver.td_end
 347    IV.  Lower bound for valid ack:      ack >= receiver.td_end - MAXACKWINDOW
 348
 349    where sack is the highest right edge of sack block found in the packet.
 350
 351    The upper bound limit for a valid ack is not ignored -
 352    we doesn't have to deal with fragments.
 353 */
 354
 355 static inline __u32 segment_seq_plus_len(__u32 seq,
 356                                          size_t len,
 357                                          unsigned int dataoff,
 358                                          struct tcphdr *tcph)
 359 {
 360         /* XXX Should I use payload length field in IP/IPv6 header ?
 361          * - YK */
 362         return (seq + len - dataoff - tcph->doff*4
 363                 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
 364 }
 365
 366 /* Fixme: what about big packets? */
 367 #define MAXACKWINCONST                  66000
 368 #define MAXACKWINDOW(sender)                                            \
 369         ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin     \
 370                                               : MAXACKWINCONST)
 371
 372 /*
 373  * Simplified tcp_parse_options routine from tcp_input.c
 374  */
 375 static void tcp_options(const struct sk_buff *skb,
 376                         unsigned int dataoff,
 377                         struct tcphdr *tcph,
 378                         struct ip_ct_tcp_state *state)
 379 {
 380         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 381         unsigned char *ptr;
 382         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 383
 384         if (!length)
 385                 return;
 386
 387         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 388                                  length, buff);
 389         BUG_ON(ptr == NULL);
 390
 391         state->td_scale =
 392         state->flags = 0;
 393
 394         while (length > 0) {
 395                 int opcode=*ptr++;
 396                 int opsize;
 397
 398                 switch (opcode) {
 399                 case TCPOPT_EOL:
 400                         return;
 401                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 402                         length--;
 403                         continue;
 404                 default:
 405                         opsize=*ptr++;
 406                         if (opsize < 2) /* "silly options" */
 407                                 return;
 408                         if (opsize > length)
 409                                 break;  /* don't parse partial options */
 410
 411                         if (opcode == TCPOPT_SACK_PERM
 412                             && opsize == TCPOLEN_SACK_PERM)
 413                                 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
 414                         else if (opcode == TCPOPT_WINDOW
 415                                  && opsize == TCPOLEN_WINDOW) {
 416                                 state->td_scale = *(u_int8_t *)ptr;
 417
 418                                 if (state->td_scale > 14) {
 419                                         /* See RFC1323 */
 420                                         state->td_scale = 14;
 421                                 }
 422                                 state->flags |=
 423                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 424                         }
 425                         ptr += opsize - 2;
 426                         length -= opsize;
 427                 }
 428         }
 429 }
 430
 431 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
 432                      struct tcphdr *tcph, __u32 *sack)
 433 {
 434         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 435         unsigned char *ptr;
 436         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 437         __u32 tmp;
 438
 439         if (!length)
 440                 return;
 441
 442         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 443                                  length, buff);
 444         BUG_ON(ptr == NULL);
 445
 446         /* Fast path for timestamp-only option */
 447         if (length == TCPOLEN_TSTAMP_ALIGNED*4
 448             && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
 449                                        | (TCPOPT_NOP << 16)
 450                                        | (TCPOPT_TIMESTAMP << 8)
 451                                        | TCPOLEN_TIMESTAMP))
 452                 return;
 453
 454         while (length > 0) {
 455                 int opcode = *ptr++;
 456                 int opsize, i;
 457
 458                 switch (opcode) {
 459                 case TCPOPT_EOL:
 460                         return;
 461                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 462                         length--;
 463                         continue;
 464                 default:
 465                         opsize = *ptr++;
 466                         if (opsize < 2) /* "silly options" */
 467                                 return;
 468                         if (opsize > length)
 469                                 break;  /* don't parse partial options */
 470
 471                         if (opcode == TCPOPT_SACK
 472                             && opsize >= (TCPOLEN_SACK_BASE
 473                                           + TCPOLEN_SACK_PERBLOCK)
 474                             && !((opsize - TCPOLEN_SACK_BASE)
 475                                  % TCPOLEN_SACK_PERBLOCK)) {
 476                                 for (i = 0;
 477                                      i < (opsize - TCPOLEN_SACK_BASE);
 478                                      i += TCPOLEN_SACK_PERBLOCK) {
 479                                         tmp = ntohl(*((__be32 *)(ptr+i)+1));
 480
 481                                         if (after(tmp, *sack))
 482                                                 *sack = tmp;
 483                                 }
 484                                 return;
 485                         }
 486                         ptr += opsize - 2;
 487                         length -= opsize;
 488                 }
 489         }
 490 }
 491
 492 static int tcp_in_window(struct nf_conn *ct,
 493                          struct ip_ct_tcp *state,
 494                          enum ip_conntrack_dir dir,
 495                          unsigned int index,
 496                          const struct sk_buff *skb,
 497                          unsigned int dataoff,
 498                          struct tcphdr *tcph,
 499                          int pf)
 500 {
 501         struct ip_ct_tcp_state *sender = &state->seen[dir];
 502         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 503         struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
 504         __u32 seq, ack, sack, end, win, swin;
 505         int res;
 506
 507         /*
 508          * Get the required data from the packet.
 509          */
 510         seq = ntohl(tcph->seq);
 511         ack = sack = ntohl(tcph->ack_seq);
 512         win = ntohs(tcph->window);
 513         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
 514
 515         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
 516                 tcp_sack(skb, dataoff, tcph, &sack);
 517
 518         pr_debug("tcp_in_window: START\n");
 519         pr_debug("tcp_in_window: ");
 520         NF_CT_DUMP_TUPLE(tuple);
 521         pr_debug("seq=%u ack=%u sack=%u win=%u end=%u\n",
 522                  seq, ack, sack, win, end);
 523         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 524                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 525                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 526                  sender->td_scale,
 527                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 528                  receiver->td_scale);
 529
 530         if (sender->td_end == 0) {
 531                 /*
 532                  * Initialize sender data.
 533                  */
 534                 if (tcph->syn && tcph->ack) {
 535                         /*
 536                          * Outgoing SYN-ACK in reply to a SYN.
 537                          */
 538                         sender->td_end =
 539                         sender->td_maxend = end;
 540                         sender->td_maxwin = (win == 0 ? 1 : win);
 541
 542                         tcp_options(skb, dataoff, tcph, sender);
 543                         /*
 544                          * RFC 1323:
 545                          * Both sides must send the Window Scale option
 546                          * to enable window scaling in either direction.
 547                          */
 548                         if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
 549                               && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
 550                                 sender->td_scale =
 551                                 receiver->td_scale = 0;
 552                 } else {
 553                         /*
 554                          * We are in the middle of a connection,
 555                          * its history is lost for us.
 556                          * Let's try to use the data from the packet.
 557                          */
 558                         sender->td_end = end;
 559                         sender->td_maxwin = (win == 0 ? 1 : win);
 560                         sender->td_maxend = end + sender->td_maxwin;
 561                 }
 562         } else if (((state->state == TCP_CONNTRACK_SYN_SENT
 563                      && dir == IP_CT_DIR_ORIGINAL)
 564                    || (state->state == TCP_CONNTRACK_SYN_RECV
 565                      && dir == IP_CT_DIR_REPLY))
 566                    && after(end, sender->td_end)) {
 567                 /*
 568                  * RFC 793: "if a TCP is reinitialized ... then it need
 569                  * not wait at all; it must only be sure to use sequence
 570                  * numbers larger than those recently used."
 571                  */
 572                 sender->td_end =
 573                 sender->td_maxend = end;
 574                 sender->td_maxwin = (win == 0 ? 1 : win);
 575
 576                 tcp_options(skb, dataoff, tcph, sender);
 577         }
 578
 579         if (!(tcph->ack)) {
 580                 /*
 581                  * If there is no ACK, just pretend it was set and OK.
 582                  */
 583                 ack = sack = receiver->td_end;
 584         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
 585                     (TCP_FLAG_ACK|TCP_FLAG_RST))
 586                    && (ack == 0)) {
 587                 /*
 588                  * Broken TCP stacks, that set ACK in RST packets as well
 589                  * with zero ack value.
 590                  */
 591                 ack = sack = receiver->td_end;
 592         }
 593
 594         if (seq == end
 595             && (!tcph->rst
 596                 || (seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)))
 597                 /*
 598                  * Packets contains no data: we assume it is valid
 599                  * and check the ack value only.
 600                  * However RST segments are always validated by their
 601                  * SEQ number, except when seq == 0 (reset sent answering
 602                  * SYN.
 603                  */
 604                 seq = end = sender->td_end;
 605
 606         pr_debug("tcp_in_window: ");
 607         NF_CT_DUMP_TUPLE(tuple);
 608         pr_debug("seq=%u ack=%u sack =%u win=%u end=%u\n",
 609                  seq, ack, sack, win, end);
 610         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 611                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 612                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 613                  sender->td_scale,
 614                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 615                  receiver->td_scale);
 616
 617         pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
 618                  before(seq, sender->td_maxend + 1),
 619                  after(end, sender->td_end - receiver->td_maxwin - 1),
 620                  before(sack, receiver->td_end + 1),
 621                  after(ack, receiver->td_end - MAXACKWINDOW(sender)));
 622
 623         if (before(seq, sender->td_maxend + 1) &&
 624             after(end, sender->td_end - receiver->td_maxwin - 1) &&
 625             before(sack, receiver->td_end + 1) &&
 626             after(ack, receiver->td_end - MAXACKWINDOW(sender))) {
 627                 /*
 628                  * Take into account window scaling (RFC 1323).
 629                  */
 630                 if (!tcph->syn)
 631                         win <<= sender->td_scale;
 632
 633                 /*
 634                  * Update sender data.
 635                  */
 636                 swin = win + (sack - ack);
 637                 if (sender->td_maxwin < swin)
 638                         sender->td_maxwin = swin;
 639                 if (after(end, sender->td_end))
 640                         sender->td_end = end;
 641                 /*
 642                  * Update receiver data.
 643                  */
 644                 if (after(end, sender->td_maxend))
 645                         receiver->td_maxwin += end - sender->td_maxend;
 646                 if (after(sack + win, receiver->td_maxend - 1)) {
 647                         receiver->td_maxend = sack + win;
 648                         if (win == 0)
 649                                 receiver->td_maxend++;
 650                 }
 651
 652                 /*
 653                  * Check retransmissions.
 654                  */
 655                 if (index == TCP_ACK_SET) {
 656                         if (state->last_dir == dir
 657                             && state->last_seq == seq
 658                             && state->last_ack == ack
 659                             && state->last_end == end
 660                             && state->last_win == win)
 661                                 state->retrans++;
 662                         else {
 663                                 state->last_dir = dir;
 664                                 state->last_seq = seq;
 665                                 state->last_ack = ack;
 666                                 state->last_end = end;
 667                                 state->last_win = win;
 668                                 state->retrans = 0;
 669                         }
 670                 }
 671                 res = 1;
 672         } else {
 673                 res = 0;
 674                 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
 675                     nf_ct_tcp_be_liberal)
 676                         res = 1;
 677                 if (!res && LOG_INVALID(IPPROTO_TCP))
 678                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 679                         "nf_ct_tcp: %s ",
 680                         before(seq, sender->td_maxend + 1) ?
 681                         after(end, sender->td_end - receiver->td_maxwin - 1) ?
 682                         before(sack, receiver->td_end + 1) ?
 683                         after(ack, receiver->td_end - MAXACKWINDOW(sender)) ? "BUG"
 684                         : "ACK is under the lower bound (possible overly delayed ACK)"
 685                         : "ACK is over the upper bound (ACKed data not seen yet)"
 686                         : "SEQ is under the lower bound (already ACKed data retransmitted)"
 687                         : "SEQ is over the upper bound (over the window of the receiver)");
 688         }
 689
 690         pr_debug("tcp_in_window: res=%i sender end=%u maxend=%u maxwin=%u "
 691                  "receiver end=%u maxend=%u maxwin=%u\n",
 692                  res, sender->td_end, sender->td_maxend, sender->td_maxwin,
 693                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
 694
 695         return res;
 696 }
 697
 698 #ifdef CONFIG_NF_NAT_NEEDED
 699 /* Update sender->td_end after NAT successfully mangled the packet */
 700 /* Caller must linearize skb at tcp header. */
 701 void nf_conntrack_tcp_update(struct sk_buff *skb,
 702                              unsigned int dataoff,
 703                              struct nf_conn *conntrack,
 704                              int dir)
 705 {
 706         struct tcphdr *tcph = (void *)skb->data + dataoff;
 707         struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[dir];
 708         struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[!dir];
 709         __u32 end;
 710
 711         end = segment_seq_plus_len(ntohl(tcph->seq), skb->len, dataoff, tcph);
 712
 713         write_lock_bh(&tcp_lock);
 714         /*
 715          * We have to worry for the ack in the reply packet only...
 716          */
 717         if (after(end, conntrack->proto.tcp.seen[dir].td_end))
 718                 conntrack->proto.tcp.seen[dir].td_end = end;
 719         conntrack->proto.tcp.last_end = end;
 720         write_unlock_bh(&tcp_lock);
 721         pr_debug("tcp_update: sender end=%u maxend=%u maxwin=%u scale=%i "
 722                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 723                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 724                  sender->td_scale,
 725                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 726                  receiver->td_scale);
 727 }
 728 EXPORT_SYMBOL_GPL(nf_conntrack_tcp_update);
 729 #endif
 730
 731 #define TH_FIN  0x01
 732 #define TH_SYN  0x02
 733 #define TH_RST  0x04
 734 #define TH_PUSH 0x08
 735 #define TH_ACK  0x10
 736 #define TH_URG  0x20
 737 #define TH_ECE  0x40
 738 #define TH_CWR  0x80
 739
 740 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
 741 static u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG) + 1] =
 742 {
 743         [TH_SYN]                        = 1,
 744         [TH_SYN|TH_URG]                 = 1,
 745         [TH_SYN|TH_ACK]                 = 1,
 746         [TH_RST]                        = 1,
 747         [TH_RST|TH_ACK]                 = 1,
 748         [TH_FIN|TH_ACK]                 = 1,
 749         [TH_FIN|TH_ACK|TH_URG]          = 1,
 750         [TH_ACK]                        = 1,
 751         [TH_ACK|TH_URG]                 = 1,
 752 };
 753
 754 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
 755 static int tcp_error(struct sk_buff *skb,
 756                      unsigned int dataoff,
 757                      enum ip_conntrack_info *ctinfo,
 758                      int pf,
 759                      unsigned int hooknum)
 760 {
 761         struct tcphdr _tcph, *th;
 762         unsigned int tcplen = skb->len - dataoff;
 763         u_int8_t tcpflags;
 764
 765         /* Smaller that minimal TCP header? */
 766         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 767         if (th == NULL) {
 768                 if (LOG_INVALID(IPPROTO_TCP))
 769                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 770                                 "nf_ct_tcp: short packet ");
 771                 return -NF_ACCEPT;
 772         }
 773
 774         /* Not whole TCP header or malformed packet */
 775         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
 776                 if (LOG_INVALID(IPPROTO_TCP))
 777                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 778                                 "nf_ct_tcp: truncated/malformed packet ");
 779                 return -NF_ACCEPT;
 780         }
 781
 782         /* Checksum invalid? Ignore.
 783          * We skip checking packets on the outgoing path
 784          * because the checksum is assumed to be correct.
 785          */
 786         /* FIXME: Source route IP option packets --RR */
 787         if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
 788             nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
 789                 if (LOG_INVALID(IPPROTO_TCP))
 790                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 791                                   "nf_ct_tcp: bad TCP checksum ");
 792                 return -NF_ACCEPT;
 793         }
 794
 795         /* Check TCP flags. */
 796         tcpflags = (((u_int8_t *)th)[13] & ~(TH_ECE|TH_CWR|TH_PUSH));
 797         if (!tcp_valid_flags[tcpflags]) {
 798                 if (LOG_INVALID(IPPROTO_TCP))
 799                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 800                                   "nf_ct_tcp: invalid TCP flag combination ");
 801                 return -NF_ACCEPT;
 802         }
 803
 804         return NF_ACCEPT;
 805 }
 806
 807 /* Returns verdict for packet, or -1 for invalid. */
 808 static int tcp_packet(struct nf_conn *conntrack,
 809                       const struct sk_buff *skb,
 810                       unsigned int dataoff,
 811                       enum ip_conntrack_info ctinfo,
 812                       int pf,
 813                       unsigned int hooknum)
 814 {
 815         struct nf_conntrack_tuple *tuple;
 816         enum tcp_conntrack new_state, old_state;
 817         enum ip_conntrack_dir dir;
 818         struct tcphdr *th, _tcph;
 819         unsigned long timeout;
 820         unsigned int index;
 821
 822         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 823         BUG_ON(th == NULL);
 824
 825         write_lock_bh(&tcp_lock);
 826         old_state = conntrack->proto.tcp.state;
 827         dir = CTINFO2DIR(ctinfo);
 828         index = get_conntrack_index(th);
 829         new_state = tcp_conntracks[dir][index][old_state];
 830         tuple = &conntrack->tuplehash[dir].tuple;
 831
 832         switch (new_state) {
 833         case TCP_CONNTRACK_SYN_SENT:
 834                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 835                         break;
 836                 if ((conntrack->proto.tcp.seen[!dir].flags &
 837                         IP_CT_TCP_FLAG_CLOSE_INIT)
 838                     || (conntrack->proto.tcp.last_dir == dir
 839                         && conntrack->proto.tcp.last_index == TCP_RST_SET)) {
 840                         /* Attempt to reopen a closed/aborted connection.
 841                          * Delete this connection and look up again. */
 842                         write_unlock_bh(&tcp_lock);
 843                         if (del_timer(&conntrack->timeout))
 844                                 conntrack->timeout.function((unsigned long)
 845                                                             conntrack);
 846                         return -NF_REPEAT;
 847                 }
 848                 /* Fall through */
 849         case TCP_CONNTRACK_IGNORE:
 850                 /* Ignored packets:
 851                  *
 852                  * a) SYN in ORIGINAL
 853                  * b) SYN/ACK in REPLY
 854                  * c) ACK in reply direction after initial SYN in original.
 855                  */
 856                 if (index == TCP_SYNACK_SET
 857                     && conntrack->proto.tcp.last_index == TCP_SYN_SET
 858                     && conntrack->proto.tcp.last_dir != dir
 859                     && ntohl(th->ack_seq) ==
 860                              conntrack->proto.tcp.last_end) {
 861                         /* This SYN/ACK acknowledges a SYN that we earlier
 862                          * ignored as invalid. This means that the client and
 863                          * the server are both in sync, while the firewall is
 864                          * not. We kill this session and block the SYN/ACK so
 865                          * that the client cannot but retransmit its SYN and
 866                          * thus initiate a clean new session.
 867                          */
 868                         write_unlock_bh(&tcp_lock);
 869                         if (LOG_INVALID(IPPROTO_TCP))
 870                                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 871                                           "nf_ct_tcp: killing out of sync session ");
 872                         if (del_timer(&conntrack->timeout))
 873                                 conntrack->timeout.function((unsigned long)
 874                                                             conntrack);
 875                         return -NF_DROP;
 876                 }
 877                 conntrack->proto.tcp.last_index = index;
 878                 conntrack->proto.tcp.last_dir = dir;
 879                 conntrack->proto.tcp.last_seq = ntohl(th->seq);
 880                 conntrack->proto.tcp.last_end =
 881                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
 882
 883                 write_unlock_bh(&tcp_lock);
 884                 if (LOG_INVALID(IPPROTO_TCP))
 885                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 886                                   "nf_ct_tcp: invalid packed ignored ");
 887                 return NF_ACCEPT;
 888         case TCP_CONNTRACK_MAX:
 889                 /* Invalid packet */
 890                 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
 891                          dir, get_conntrack_index(th), old_state);
 892                 write_unlock_bh(&tcp_lock);
 893                 if (LOG_INVALID(IPPROTO_TCP))
 894                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 895                                   "nf_ct_tcp: invalid state ");
 896                 return -NF_ACCEPT;
 897         case TCP_CONNTRACK_CLOSE:
 898                 if (index == TCP_RST_SET
 899                     && ((test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)
 900                          && conntrack->proto.tcp.last_index == TCP_SYN_SET)
 901                         || (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
 902                             && conntrack->proto.tcp.last_index == TCP_ACK_SET))
 903                     && ntohl(th->ack_seq) == conntrack->proto.tcp.last_end) {
 904                         /* RST sent to invalid SYN or ACK we had let through
 905                          * at a) and c) above:
 906                          *
 907                          * a) SYN was in window then
 908                          * c) we hold a half-open connection.
 909                          *
 910                          * Delete our connection entry.
 911                          * We skip window checking, because packet might ACK
 912                          * segments we ignored. */
 913                         goto in_window;
 914                 }
 915                 /* Just fall through */
 916         default:
 917                 /* Keep compilers happy. */
 918                 break;
 919         }
 920
 921         if (!tcp_in_window(conntrack, &conntrack->proto.tcp, dir, index,
 922                            skb, dataoff, th, pf)) {
 923                 write_unlock_bh(&tcp_lock);
 924                 return -NF_ACCEPT;
 925         }
 926      in_window:
 927         /* From now on we have got in-window packets */
 928         conntrack->proto.tcp.last_index = index;
 929         conntrack->proto.tcp.last_dir = dir;
 930
 931         pr_debug("tcp_conntracks: ");
 932         NF_CT_DUMP_TUPLE(tuple);
 933         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
 934                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
 935                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
 936                  old_state, new_state);
 937
 938         conntrack->proto.tcp.state = new_state;
 939         if (old_state != new_state
 940             && (new_state == TCP_CONNTRACK_FIN_WAIT
 941                 || new_state == TCP_CONNTRACK_CLOSE))
 942                 conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
 943         timeout = conntrack->proto.tcp.retrans >= nf_ct_tcp_max_retrans
 944                   && *tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans
 945                   ? nf_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state];
 946         write_unlock_bh(&tcp_lock);
 947
 948         nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
 949         if (new_state != old_state)
 950                 nf_conntrack_event_cache(IPCT_PROTOINFO, skb);
 951
 952         if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
 953                 /* If only reply is a RST, we can consider ourselves not to
 954                    have an established connection: this is a fairly common
 955                    problem case, so we can delete the conntrack
 956                    immediately.  --RR */
 957                 if (th->rst) {
 958                         if (del_timer(&conntrack->timeout))
 959                                 conntrack->timeout.function((unsigned long)
 960                                                             conntrack);
 961                         return NF_ACCEPT;
 962                 }
 963         } else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
 964                    && (old_state == TCP_CONNTRACK_SYN_RECV
 965                        || old_state == TCP_CONNTRACK_ESTABLISHED)
 966                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
 967                 /* Set ASSURED if we see see valid ack in ESTABLISHED
 968                    after SYN_RECV or a valid answer for a picked up
 969                    connection. */
 970                 set_bit(IPS_ASSURED_BIT, &conntrack->status);
 971                 nf_conntrack_event_cache(IPCT_STATUS, skb);
 972         }
 973         nf_ct_refresh_acct(conntrack, ctinfo, skb, timeout);
 974
 975         return NF_ACCEPT;
 976 }
 977
 978 /* Called when a new connection for this protocol found. */
 979 static int tcp_new(struct nf_conn *conntrack,
 980                    const struct sk_buff *skb,
 981                    unsigned int dataoff)
 982 {
 983         enum tcp_conntrack new_state;
 984         struct tcphdr *th, _tcph;
 985         struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[0];
 986         struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[1];
 987
 988         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 989         BUG_ON(th == NULL);
 990
 991         /* Don't need lock here: this conntrack not in circulation yet */
 992         new_state
 993                 = tcp_conntracks[0][get_conntrack_index(th)]
 994                 [TCP_CONNTRACK_NONE];
 995
 996         /* Invalid: delete conntrack */
 997         if (new_state >= TCP_CONNTRACK_MAX) {
 998                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
 999                 return 0;
1000         }
1001
1002         if (new_state == TCP_CONNTRACK_SYN_SENT) {
1003                 /* SYN packet */
1004                 conntrack->proto.tcp.seen[0].td_end =
1005                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1006                                              dataoff, th);
1007                 conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1008                 if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
1009                         conntrack->proto.tcp.seen[0].td_maxwin = 1;
1010                 conntrack->proto.tcp.seen[0].td_maxend =
1011                         conntrack->proto.tcp.seen[0].td_end;
1012
1013                 tcp_options(skb, dataoff, th, &conntrack->proto.tcp.seen[0]);
1014                 conntrack->proto.tcp.seen[1].flags = 0;
1015         } else if (nf_ct_tcp_loose == 0) {
1016                 /* Don't try to pick up connections. */
1017                 return 0;
1018         } else {
1019                 /*
1020                  * We are in the middle of a connection,
1021                  * its history is lost for us.
1022                  * Let's try to use the data from the packet.
1023                  */
1024                 conntrack->proto.tcp.seen[0].td_end =
1025                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1026                                              dataoff, th);
1027                 conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1028                 if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
1029                         conntrack->proto.tcp.seen[0].td_maxwin = 1;
1030                 conntrack->proto.tcp.seen[0].td_maxend =
1031                         conntrack->proto.tcp.seen[0].td_end +
1032                         conntrack->proto.tcp.seen[0].td_maxwin;
1033                 conntrack->proto.tcp.seen[0].td_scale = 0;
1034
1035                 /* We assume SACK and liberal window checking to handle
1036                  * window scaling */
1037                 conntrack->proto.tcp.seen[0].flags =
1038                 conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
1039                                                      IP_CT_TCP_FLAG_BE_LIBERAL;
1040         }
1041
1042         conntrack->proto.tcp.seen[1].td_end = 0;
1043         conntrack->proto.tcp.seen[1].td_maxend = 0;
1044         conntrack->proto.tcp.seen[1].td_maxwin = 1;
1045         conntrack->proto.tcp.seen[1].td_scale = 0;
1046
1047         /* tcp_packet will set them */
1048         conntrack->proto.tcp.state = TCP_CONNTRACK_NONE;
1049         conntrack->proto.tcp.last_index = TCP_NONE_SET;
1050
1051         pr_debug("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
1052                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
1053                  sender->td_end, sender->td_maxend, sender->td_maxwin,
1054                  sender->td_scale,
1055                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
1056                  receiver->td_scale);
1057         return 1;
1058 }
1059
1060 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1061
1062 #include <linux/netfilter/nfnetlink.h>
1063 #include <linux/netfilter/nfnetlink_conntrack.h>
1064
1065 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1066                          const struct nf_conn *ct)
1067 {
1068         struct nlattr *nest_parms;
1069         struct nf_ct_tcp_flags tmp = {};
1070
1071         read_lock_bh(&tcp_lock);
1072         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP | NLA_F_NESTED);
1073         if (!nest_parms)
1074                 goto nla_put_failure;
1075
1076         NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state);
1077
1078         NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1079                    ct->proto.tcp.seen[0].td_scale);
1080
1081         NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1082                    ct->proto.tcp.seen[1].td_scale);
1083
1084         tmp.flags = ct->proto.tcp.seen[0].flags;
1085         NLA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1086                 sizeof(struct nf_ct_tcp_flags), &tmp);
1087
1088         tmp.flags = ct->proto.tcp.seen[1].flags;
1089         NLA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1090                 sizeof(struct nf_ct_tcp_flags), &tmp);
1091         read_unlock_bh(&tcp_lock);
1092
1093         nla_nest_end(skb, nest_parms);
1094
1095         return 0;
1096
1097 nla_put_failure:
1098         read_unlock_bh(&tcp_lock);
1099         return -1;
1100 }
1101
1102 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1103         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1104         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1105         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1106         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1107         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len =  sizeof(struct nf_ct_tcp_flags) },
1108 };
1109
1110 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1111 {
1112         struct nlattr *attr = cda[CTA_PROTOINFO_TCP];
1113         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1114         int err;
1115
1116         /* updates could not contain anything about the private
1117          * protocol info, in that case skip the parsing */
1118         if (!attr)
1119                 return 0;
1120
1121         err = nla_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, attr, tcp_nla_policy);
1122         if (err < 0)
1123                 return err;
1124
1125         if (!tb[CTA_PROTOINFO_TCP_STATE])
1126                 return -EINVAL;
1127
1128         write_lock_bh(&tcp_lock);
1129         ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1130
1131         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1132                 struct nf_ct_tcp_flags *attr =
1133                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1134                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1135                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1136         }
1137
1138         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1139                 struct nf_ct_tcp_flags *attr =
1140                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1141                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1142                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1143         }
1144
1145         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1146             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1147             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1148             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1149                 ct->proto.tcp.seen[0].td_scale =
1150                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1151                 ct->proto.tcp.seen[1].td_scale =
1152                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1153         }
1154         write_unlock_bh(&tcp_lock);
1155
1156         return 0;
1157 }
1158 #endif
1159
1160 #ifdef CONFIG_SYSCTL
1161 static unsigned int tcp_sysctl_table_users;
1162 static struct ctl_table_header *tcp_sysctl_header;
1163 static struct ctl_table tcp_sysctl_table[] = {
1164         {
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                 .procname       = "nf_conntrack_tcp_timeout_syn_recv",
1173                 .data           = &nf_ct_tcp_timeout_syn_recv,
1174                 .maxlen         = sizeof(unsigned int),
1175                 .mode           = 0644,
1176                 .proc_handler   = &proc_dointvec_jiffies,
1177         },
1178         {
1179                 .procname       = "nf_conntrack_tcp_timeout_established",
1180                 .data           = &nf_ct_tcp_timeout_established,
1181                 .maxlen         = sizeof(unsigned int),
1182                 .mode           = 0644,
1183                 .proc_handler   = &proc_dointvec_jiffies,
1184         },
1185         {
1186                 .procname       = "nf_conntrack_tcp_timeout_fin_wait",
1187                 .data           = &nf_ct_tcp_timeout_fin_wait,
1188                 .maxlen         = sizeof(unsigned int),
1189                 .mode           = 0644,
1190                 .proc_handler   = &proc_dointvec_jiffies,
1191         },
1192         {
1193                 .procname       = "nf_conntrack_tcp_timeout_close_wait",
1194                 .data           = &nf_ct_tcp_timeout_close_wait,
1195                 .maxlen         = sizeof(unsigned int),
1196                 .mode           = 0644,
1197                 .proc_handler   = &proc_dointvec_jiffies,
1198         },
1199         {
1200                 .procname       = "nf_conntrack_tcp_timeout_last_ack",
1201                 .data           = &nf_ct_tcp_timeout_last_ack,
1202                 .maxlen         = sizeof(unsigned int),
1203                 .mode           = 0644,
1204                 .proc_handler   = &proc_dointvec_jiffies,
1205         },
1206         {
1207                 .procname       = "nf_conntrack_tcp_timeout_time_wait",
1208                 .data           = &nf_ct_tcp_timeout_time_wait,
1209                 .maxlen         = sizeof(unsigned int),
1210                 .mode           = 0644,
1211                 .proc_handler   = &proc_dointvec_jiffies,
1212         },
1213         {
1214                 .procname       = "nf_conntrack_tcp_timeout_close",
1215                 .data           = &nf_ct_tcp_timeout_close,
1216                 .maxlen         = sizeof(unsigned int),
1217                 .mode           = 0644,
1218                 .proc_handler   = &proc_dointvec_jiffies,
1219         },
1220         {
1221                 .procname       = "nf_conntrack_tcp_timeout_max_retrans",
1222                 .data           = &nf_ct_tcp_timeout_max_retrans,
1223                 .maxlen         = sizeof(unsigned int),
1224                 .mode           = 0644,
1225                 .proc_handler   = &proc_dointvec_jiffies,
1226         },
1227         {
1228                 .ctl_name       = NET_NF_CONNTRACK_TCP_LOOSE,
1229                 .procname       = "nf_conntrack_tcp_loose",
1230                 .data           = &nf_ct_tcp_loose,
1231                 .maxlen         = sizeof(unsigned int),
1232                 .mode           = 0644,
1233                 .proc_handler   = &proc_dointvec,
1234         },
1235         {
1236                 .ctl_name       = NET_NF_CONNTRACK_TCP_BE_LIBERAL,
1237                 .procname       = "nf_conntrack_tcp_be_liberal",
1238                 .data           = &nf_ct_tcp_be_liberal,
1239                 .maxlen         = sizeof(unsigned int),
1240                 .mode           = 0644,
1241                 .proc_handler   = &proc_dointvec,
1242         },
1243         {
1244                 .ctl_name       = NET_NF_CONNTRACK_TCP_MAX_RETRANS,
1245                 .procname       = "nf_conntrack_tcp_max_retrans",
1246                 .data           = &nf_ct_tcp_max_retrans,
1247                 .maxlen         = sizeof(unsigned int),
1248                 .mode           = 0644,
1249                 .proc_handler   = &proc_dointvec,
1250         },
1251         {
1252                 .ctl_name       = 0
1253         }
1254 };
1255
1256 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1257 static struct ctl_table tcp_compat_sysctl_table[] = {
1258         {
1259                 .procname       = "ip_conntrack_tcp_timeout_syn_sent",
1260                 .data           = &nf_ct_tcp_timeout_syn_sent,
1261                 .maxlen         = sizeof(unsigned int),
1262                 .mode           = 0644,
1263                 .proc_handler   = &proc_dointvec_jiffies,
1264         },
1265         {
1266                 .procname       = "ip_conntrack_tcp_timeout_syn_recv",
1267                 .data           = &nf_ct_tcp_timeout_syn_recv,
1268                 .maxlen         = sizeof(unsigned int),
1269                 .mode           = 0644,
1270                 .proc_handler   = &proc_dointvec_jiffies,
1271         },
1272         {
1273                 .procname       = "ip_conntrack_tcp_timeout_established",
1274                 .data           = &nf_ct_tcp_timeout_established,
1275                 .maxlen         = sizeof(unsigned int),
1276                 .mode           = 0644,
1277                 .proc_handler   = &proc_dointvec_jiffies,
1278         },
1279         {
1280                 .procname       = "ip_conntrack_tcp_timeout_fin_wait",
1281                 .data           = &nf_ct_tcp_timeout_fin_wait,
1282                 .maxlen         = sizeof(unsigned int),
1283                 .mode           = 0644,
1284                 .proc_handler   = &proc_dointvec_jiffies,
1285         },
1286         {
1287                 .procname       = "ip_conntrack_tcp_timeout_close_wait",
1288                 .data           = &nf_ct_tcp_timeout_close_wait,
1289                 .maxlen         = sizeof(unsigned int),
1290                 .mode           = 0644,
1291                 .proc_handler   = &proc_dointvec_jiffies,
1292         },
1293         {
1294                 .procname       = "ip_conntrack_tcp_timeout_last_ack",
1295                 .data           = &nf_ct_tcp_timeout_last_ack,
1296                 .maxlen         = sizeof(unsigned int),
1297                 .mode           = 0644,
1298                 .proc_handler   = &proc_dointvec_jiffies,
1299         },
1300         {
1301                 .procname       = "ip_conntrack_tcp_timeout_time_wait",
1302                 .data           = &nf_ct_tcp_timeout_time_wait,
1303                 .maxlen         = sizeof(unsigned int),
1304                 .mode           = 0644,
1305                 .proc_handler   = &proc_dointvec_jiffies,
1306         },
1307         {
1308                 .procname       = "ip_conntrack_tcp_timeout_close",
1309                 .data           = &nf_ct_tcp_timeout_close,
1310                 .maxlen         = sizeof(unsigned int),
1311                 .mode           = 0644,
1312                 .proc_handler   = &proc_dointvec_jiffies,
1313         },
1314         {
1315                 .procname       = "ip_conntrack_tcp_timeout_max_retrans",
1316                 .data           = &nf_ct_tcp_timeout_max_retrans,
1317                 .maxlen         = sizeof(unsigned int),
1318                 .mode           = 0644,
1319                 .proc_handler   = &proc_dointvec_jiffies,
1320         },
1321         {
1322                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_LOOSE,
1323                 .procname       = "ip_conntrack_tcp_loose",
1324                 .data           = &nf_ct_tcp_loose,
1325                 .maxlen         = sizeof(unsigned int),
1326                 .mode           = 0644,
1327                 .proc_handler   = &proc_dointvec,
1328         },
1329         {
1330                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_BE_LIBERAL,
1331                 .procname       = "ip_conntrack_tcp_be_liberal",
1332                 .data           = &nf_ct_tcp_be_liberal,
1333                 .maxlen         = sizeof(unsigned int),
1334                 .mode           = 0644,
1335                 .proc_handler   = &proc_dointvec,
1336         },
1337         {
1338                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_MAX_RETRANS,
1339                 .procname       = "ip_conntrack_tcp_max_retrans",
1340                 .data           = &nf_ct_tcp_max_retrans,
1341                 .maxlen         = sizeof(unsigned int),
1342                 .mode           = 0644,
1343                 .proc_handler   = &proc_dointvec,
1344         },
1345         {
1346                 .ctl_name       = 0
1347         }
1348 };
1349 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
1350 #endif /* CONFIG_SYSCTL */
1351
1352 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 __read_mostly =
1353 {
1354         .l3proto                = PF_INET,
1355         .l4proto                = IPPROTO_TCP,
1356         .name                   = "tcp",
1357         .pkt_to_tuple           = tcp_pkt_to_tuple,
1358         .invert_tuple           = tcp_invert_tuple,
1359         .print_tuple            = tcp_print_tuple,
1360         .print_conntrack        = tcp_print_conntrack,
1361         .packet                 = tcp_packet,
1362         .new                    = tcp_new,
1363         .error                  = tcp_error,
1364 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1365         .to_nlattr              = tcp_to_nlattr,
1366         .from_nlattr            = nlattr_to_tcp,
1367         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1368         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1369         .nla_policy             = nf_ct_port_nla_policy,
1370 #endif
1371 #ifdef CONFIG_SYSCTL
1372         .ctl_table_users        = &tcp_sysctl_table_users,
1373         .ctl_table_header       = &tcp_sysctl_header,
1374         .ctl_table              = tcp_sysctl_table,
1375 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1376         .ctl_compat_table       = tcp_compat_sysctl_table,
1377 #endif
1378 #endif
1379 };
1380 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp4);
1381
1382 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp6 __read_mostly =
1383 {
1384         .l3proto                = PF_INET6,
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) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1395         .to_nlattr              = tcp_to_nlattr,
1396         .from_nlattr            = nlattr_to_tcp,
1397         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1398         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1399         .nla_policy             = nf_ct_port_nla_policy,
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 #endif
1406 };
1407 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp6);