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/netfilter.h>
  12 #include <linux/module.h>
  13 #include <linux/in.h>
  14 #include <linux/tcp.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/ipv6.h>
  18 #include <net/ip6_checksum.h>
  19
  20 #include <net/tcp.h>
  21
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter_ipv4.h>
  24 #include <linux/netfilter_ipv6.h>
  25 #include <net/netfilter/nf_conntrack.h>
  26 #include <net/netfilter/nf_conntrack_l4proto.h>
  27 #include <net/netfilter/nf_conntrack_ecache.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 enum tcp_conntrack 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 &&
 788             ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
 789              (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) &&
 790             nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
 791                 if (LOG_INVALID(IPPROTO_TCP))
 792                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 793                                   "nf_ct_tcp: bad TCP checksum ");
 794                 return -NF_ACCEPT;
 795         }
 796
 797         /* Check TCP flags. */
 798         tcpflags = (((u_int8_t *)th)[13] & ~(TH_ECE|TH_CWR|TH_PUSH));
 799         if (!tcp_valid_flags[tcpflags]) {
 800                 if (LOG_INVALID(IPPROTO_TCP))
 801                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 802                                   "nf_ct_tcp: invalid TCP flag combination ");
 803                 return -NF_ACCEPT;
 804         }
 805
 806         return NF_ACCEPT;
 807 }
 808
 809 /* Returns verdict for packet, or -1 for invalid. */
 810 static int tcp_packet(struct nf_conn *conntrack,
 811                       const struct sk_buff *skb,
 812                       unsigned int dataoff,
 813                       enum ip_conntrack_info ctinfo,
 814                       int pf,
 815                       unsigned int hooknum)
 816 {
 817         struct nf_conntrack_tuple *tuple;
 818         enum tcp_conntrack new_state, old_state;
 819         enum ip_conntrack_dir dir;
 820         struct tcphdr *th, _tcph;
 821         unsigned long timeout;
 822         unsigned int index;
 823
 824         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 825         BUG_ON(th == NULL);
 826
 827         write_lock_bh(&tcp_lock);
 828         old_state = conntrack->proto.tcp.state;
 829         dir = CTINFO2DIR(ctinfo);
 830         index = get_conntrack_index(th);
 831         new_state = tcp_conntracks[dir][index][old_state];
 832         tuple = &conntrack->tuplehash[dir].tuple;
 833
 834         switch (new_state) {
 835         case TCP_CONNTRACK_IGNORE:
 836                 /* Ignored packets:
 837                  *
 838                  * a) SYN in ORIGINAL
 839                  * b) SYN/ACK in REPLY
 840                  * c) ACK in reply direction after initial SYN in original.
 841                  */
 842                 if (index == TCP_SYNACK_SET
 843                     && conntrack->proto.tcp.last_index == TCP_SYN_SET
 844                     && conntrack->proto.tcp.last_dir != dir
 845                     && ntohl(th->ack_seq) ==
 846                              conntrack->proto.tcp.last_end) {
 847                         /* This SYN/ACK acknowledges a SYN that we earlier
 848                          * ignored as invalid. This means that the client and
 849                          * the server are both in sync, while the firewall is
 850                          * not. We kill this session and block the SYN/ACK so
 851                          * that the client cannot but retransmit its SYN and
 852                          * thus initiate a clean new session.
 853                          */
 854                         write_unlock_bh(&tcp_lock);
 855                         if (LOG_INVALID(IPPROTO_TCP))
 856                                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 857                                           "nf_ct_tcp: killing out of sync session ");
 858                         if (del_timer(&conntrack->timeout))
 859                                 conntrack->timeout.function((unsigned long)
 860                                                             conntrack);
 861                         return -NF_DROP;
 862                 }
 863                 conntrack->proto.tcp.last_index = index;
 864                 conntrack->proto.tcp.last_dir = dir;
 865                 conntrack->proto.tcp.last_seq = ntohl(th->seq);
 866                 conntrack->proto.tcp.last_end =
 867                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
 868
 869                 write_unlock_bh(&tcp_lock);
 870                 if (LOG_INVALID(IPPROTO_TCP))
 871                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 872                                   "nf_ct_tcp: invalid packed ignored ");
 873                 return NF_ACCEPT;
 874         case TCP_CONNTRACK_MAX:
 875                 /* Invalid packet */
 876                 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
 877                          dir, get_conntrack_index(th), old_state);
 878                 write_unlock_bh(&tcp_lock);
 879                 if (LOG_INVALID(IPPROTO_TCP))
 880                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 881                                   "nf_ct_tcp: invalid state ");
 882                 return -NF_ACCEPT;
 883         case TCP_CONNTRACK_SYN_SENT:
 884                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 885                         break;
 886                 if ((conntrack->proto.tcp.seen[dir].flags &
 887                         IP_CT_TCP_FLAG_CLOSE_INIT)
 888                     || after(ntohl(th->seq),
 889                              conntrack->proto.tcp.seen[dir].td_end)) {
 890                         /* Attempt to reopen a closed connection.
 891                         * Delete this connection and look up again. */
 892                         write_unlock_bh(&tcp_lock);
 893                         if (del_timer(&conntrack->timeout))
 894                                 conntrack->timeout.function((unsigned long)
 895                                                             conntrack);
 896                         return -NF_REPEAT;
 897                 } else {
 898                         write_unlock_bh(&tcp_lock);
 899                         if (LOG_INVALID(IPPROTO_TCP))
 900                                 nf_log_packet(pf, 0, skb, NULL, NULL,
 901                                               NULL, "nf_ct_tcp: invalid SYN");
 902                         return -NF_ACCEPT;
 903                 }
 904         case TCP_CONNTRACK_CLOSE:
 905                 if (index == TCP_RST_SET
 906                     && ((test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)
 907                          && conntrack->proto.tcp.last_index == TCP_SYN_SET)
 908                         || (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
 909                             && conntrack->proto.tcp.last_index == TCP_ACK_SET))
 910                     && ntohl(th->ack_seq) == conntrack->proto.tcp.last_end) {
 911                         /* RST sent to invalid SYN or ACK we had let through
 912                          * at a) and c) above:
 913                          *
 914                          * a) SYN was in window then
 915                          * c) we hold a half-open connection.
 916                          *
 917                          * Delete our connection entry.
 918                          * We skip window checking, because packet might ACK
 919                          * segments we ignored. */
 920                         goto in_window;
 921                 }
 922                 /* Just fall through */
 923         default:
 924                 /* Keep compilers happy. */
 925                 break;
 926         }
 927
 928         if (!tcp_in_window(conntrack, &conntrack->proto.tcp, dir, index,
 929                            skb, dataoff, th, pf)) {
 930                 write_unlock_bh(&tcp_lock);
 931                 return -NF_ACCEPT;
 932         }
 933      in_window:
 934         /* From now on we have got in-window packets */
 935         conntrack->proto.tcp.last_index = index;
 936
 937         pr_debug("tcp_conntracks: ");
 938         NF_CT_DUMP_TUPLE(tuple);
 939         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
 940                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
 941                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
 942                  old_state, new_state);
 943
 944         conntrack->proto.tcp.state = new_state;
 945         if (old_state != new_state
 946             && (new_state == TCP_CONNTRACK_FIN_WAIT
 947                 || new_state == TCP_CONNTRACK_CLOSE))
 948                 conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
 949         timeout = conntrack->proto.tcp.retrans >= nf_ct_tcp_max_retrans
 950                   && *tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans
 951                   ? nf_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state];
 952         write_unlock_bh(&tcp_lock);
 953
 954         nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
 955         if (new_state != old_state)
 956                 nf_conntrack_event_cache(IPCT_PROTOINFO, skb);
 957
 958         if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
 959                 /* If only reply is a RST, we can consider ourselves not to
 960                    have an established connection: this is a fairly common
 961                    problem case, so we can delete the conntrack
 962                    immediately.  --RR */
 963                 if (th->rst) {
 964                         if (del_timer(&conntrack->timeout))
 965                                 conntrack->timeout.function((unsigned long)
 966                                                             conntrack);
 967                         return NF_ACCEPT;
 968                 }
 969         } else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
 970                    && (old_state == TCP_CONNTRACK_SYN_RECV
 971                        || old_state == TCP_CONNTRACK_ESTABLISHED)
 972                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
 973                 /* Set ASSURED if we see see valid ack in ESTABLISHED
 974                    after SYN_RECV or a valid answer for a picked up
 975                    connection. */
 976                 set_bit(IPS_ASSURED_BIT, &conntrack->status);
 977                 nf_conntrack_event_cache(IPCT_STATUS, skb);
 978         }
 979         nf_ct_refresh_acct(conntrack, ctinfo, skb, timeout);
 980
 981         return NF_ACCEPT;
 982 }
 983
 984 /* Called when a new connection for this protocol found. */
 985 static int tcp_new(struct nf_conn *conntrack,
 986                    const struct sk_buff *skb,
 987                    unsigned int dataoff)
 988 {
 989         enum tcp_conntrack new_state;
 990         struct tcphdr *th, _tcph;
 991         struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[0];
 992         struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[1];
 993
 994         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 995         BUG_ON(th == NULL);
 996
 997         /* Don't need lock here: this conntrack not in circulation yet */
 998         new_state
 999                 = tcp_conntracks[0][get_conntrack_index(th)]
1000                 [TCP_CONNTRACK_NONE];
1001
1002         /* Invalid: delete conntrack */
1003         if (new_state >= TCP_CONNTRACK_MAX) {
1004                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
1005                 return 0;
1006         }
1007
1008         if (new_state == TCP_CONNTRACK_SYN_SENT) {
1009                 /* SYN packet */
1010                 conntrack->proto.tcp.seen[0].td_end =
1011                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1012                                              dataoff, th);
1013                 conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1014                 if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
1015                         conntrack->proto.tcp.seen[0].td_maxwin = 1;
1016                 conntrack->proto.tcp.seen[0].td_maxend =
1017                         conntrack->proto.tcp.seen[0].td_end;
1018
1019                 tcp_options(skb, dataoff, th, &conntrack->proto.tcp.seen[0]);
1020                 conntrack->proto.tcp.seen[1].flags = 0;
1021         } else if (nf_ct_tcp_loose == 0) {
1022                 /* Don't try to pick up connections. */
1023                 return 0;
1024         } else {
1025                 /*
1026                  * We are in the middle of a connection,
1027                  * its history is lost for us.
1028                  * Let's try to use the data from the packet.
1029                  */
1030                 conntrack->proto.tcp.seen[0].td_end =
1031                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1032                                              dataoff, th);
1033                 conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1034                 if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
1035                         conntrack->proto.tcp.seen[0].td_maxwin = 1;
1036                 conntrack->proto.tcp.seen[0].td_maxend =
1037                         conntrack->proto.tcp.seen[0].td_end +
1038                         conntrack->proto.tcp.seen[0].td_maxwin;
1039                 conntrack->proto.tcp.seen[0].td_scale = 0;
1040
1041                 /* We assume SACK and liberal window checking to handle
1042                  * window scaling */
1043                 conntrack->proto.tcp.seen[0].flags =
1044                 conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
1045                                                      IP_CT_TCP_FLAG_BE_LIBERAL;
1046         }
1047
1048         conntrack->proto.tcp.seen[1].td_end = 0;
1049         conntrack->proto.tcp.seen[1].td_maxend = 0;
1050         conntrack->proto.tcp.seen[1].td_maxwin = 1;
1051         conntrack->proto.tcp.seen[1].td_scale = 0;
1052
1053         /* tcp_packet will set them */
1054         conntrack->proto.tcp.state = TCP_CONNTRACK_NONE;
1055         conntrack->proto.tcp.last_index = TCP_NONE_SET;
1056
1057         pr_debug("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
1058                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
1059                  sender->td_end, sender->td_maxend, sender->td_maxwin,
1060                  sender->td_scale,
1061                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
1062                  receiver->td_scale);
1063         return 1;
1064 }
1065
1066 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1067
1068 #include <linux/netfilter/nfnetlink.h>
1069 #include <linux/netfilter/nfnetlink_conntrack.h>
1070
1071 static int tcp_to_nfattr(struct sk_buff *skb, struct nfattr *nfa,
1072                          const struct nf_conn *ct)
1073 {
1074         struct nfattr *nest_parms;
1075         struct nf_ct_tcp_flags tmp = {};
1076
1077         read_lock_bh(&tcp_lock);
1078         nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
1079         NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t),
1080                 &ct->proto.tcp.state);
1081
1082         NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL, sizeof(u_int8_t),
1083                 &ct->proto.tcp.seen[0].td_scale);
1084
1085         NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY, sizeof(u_int8_t),
1086                 &ct->proto.tcp.seen[1].td_scale);
1087
1088         tmp.flags = ct->proto.tcp.seen[0].flags;
1089         NFA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1090                 sizeof(struct nf_ct_tcp_flags), &tmp);
1091
1092         tmp.flags = ct->proto.tcp.seen[1].flags;
1093         NFA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1094                 sizeof(struct nf_ct_tcp_flags), &tmp);
1095         read_unlock_bh(&tcp_lock);
1096
1097         NFA_NEST_END(skb, nest_parms);
1098
1099         return 0;
1100
1101 nfattr_failure:
1102         read_unlock_bh(&tcp_lock);
1103         return -1;
1104 }
1105
1106 static const size_t cta_min_tcp[CTA_PROTOINFO_TCP_MAX] = {
1107         [CTA_PROTOINFO_TCP_STATE-1]           = sizeof(u_int8_t),
1108         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] = sizeof(u_int8_t),
1109         [CTA_PROTOINFO_TCP_WSCALE_REPLY-1]    = sizeof(u_int8_t),
1110         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL-1]  = sizeof(struct nf_ct_tcp_flags),
1111         [CTA_PROTOINFO_TCP_FLAGS_REPLY-1]     = sizeof(struct nf_ct_tcp_flags)
1112 };
1113
1114 static int nfattr_to_tcp(struct nfattr *cda[], struct nf_conn *ct)
1115 {
1116         struct nfattr *attr = cda[CTA_PROTOINFO_TCP-1];
1117         struct nfattr *tb[CTA_PROTOINFO_TCP_MAX];
1118
1119         /* updates could not contain anything about the private
1120          * protocol info, in that case skip the parsing */
1121         if (!attr)
1122                 return 0;
1123
1124         nfattr_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, attr);
1125
1126         if (nfattr_bad_size(tb, CTA_PROTOINFO_TCP_MAX, cta_min_tcp))
1127                 return -EINVAL;
1128
1129         if (!tb[CTA_PROTOINFO_TCP_STATE-1])
1130                 return -EINVAL;
1131
1132         write_lock_bh(&tcp_lock);
1133         ct->proto.tcp.state =
1134                 *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_STATE-1]);
1135
1136         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL-1]) {
1137                 struct nf_ct_tcp_flags *attr =
1138                         NFA_DATA(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL-1]);
1139                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1140                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1141         }
1142
1143         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY-1]) {
1144                 struct nf_ct_tcp_flags *attr =
1145                         NFA_DATA(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY-1]);
1146                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1147                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1148         }
1149
1150         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] &&
1151             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1] &&
1152             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1153             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1154                 ct->proto.tcp.seen[0].td_scale = *(u_int8_t *)
1155                         NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1]);
1156                 ct->proto.tcp.seen[1].td_scale = *(u_int8_t *)
1157                         NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1]);
1158         }
1159         write_unlock_bh(&tcp_lock);
1160
1161         return 0;
1162 }
1163 #endif
1164
1165 #ifdef CONFIG_SYSCTL
1166 static unsigned int tcp_sysctl_table_users;
1167 static struct ctl_table_header *tcp_sysctl_header;
1168 static struct ctl_table tcp_sysctl_table[] = {
1169         {
1170                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_SYN_SENT,
1171                 .procname       = "nf_conntrack_tcp_timeout_syn_sent",
1172                 .data           = &nf_ct_tcp_timeout_syn_sent,
1173                 .maxlen         = sizeof(unsigned int),
1174                 .mode           = 0644,
1175                 .proc_handler   = &proc_dointvec_jiffies,
1176         },
1177         {
1178                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_SYN_RECV,
1179                 .procname       = "nf_conntrack_tcp_timeout_syn_recv",
1180                 .data           = &nf_ct_tcp_timeout_syn_recv,
1181                 .maxlen         = sizeof(unsigned int),
1182                 .mode           = 0644,
1183                 .proc_handler   = &proc_dointvec_jiffies,
1184         },
1185         {
1186                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_ESTABLISHED,
1187                 .procname       = "nf_conntrack_tcp_timeout_established",
1188                 .data           = &nf_ct_tcp_timeout_established,
1189                 .maxlen         = sizeof(unsigned int),
1190                 .mode           = 0644,
1191                 .proc_handler   = &proc_dointvec_jiffies,
1192         },
1193         {
1194                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_FIN_WAIT,
1195                 .procname       = "nf_conntrack_tcp_timeout_fin_wait",
1196                 .data           = &nf_ct_tcp_timeout_fin_wait,
1197                 .maxlen         = sizeof(unsigned int),
1198                 .mode           = 0644,
1199                 .proc_handler   = &proc_dointvec_jiffies,
1200         },
1201         {
1202                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_CLOSE_WAIT,
1203                 .procname       = "nf_conntrack_tcp_timeout_close_wait",
1204                 .data           = &nf_ct_tcp_timeout_close_wait,
1205                 .maxlen         = sizeof(unsigned int),
1206                 .mode           = 0644,
1207                 .proc_handler   = &proc_dointvec_jiffies,
1208         },
1209         {
1210                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_LAST_ACK,
1211                 .procname       = "nf_conntrack_tcp_timeout_last_ack",
1212                 .data           = &nf_ct_tcp_timeout_last_ack,
1213                 .maxlen         = sizeof(unsigned int),
1214                 .mode           = 0644,
1215                 .proc_handler   = &proc_dointvec_jiffies,
1216         },
1217         {
1218                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_TIME_WAIT,
1219                 .procname       = "nf_conntrack_tcp_timeout_time_wait",
1220                 .data           = &nf_ct_tcp_timeout_time_wait,
1221                 .maxlen         = sizeof(unsigned int),
1222                 .mode           = 0644,
1223                 .proc_handler   = &proc_dointvec_jiffies,
1224         },
1225         {
1226                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_CLOSE,
1227                 .procname       = "nf_conntrack_tcp_timeout_close",
1228                 .data           = &nf_ct_tcp_timeout_close,
1229                 .maxlen         = sizeof(unsigned int),
1230                 .mode           = 0644,
1231                 .proc_handler   = &proc_dointvec_jiffies,
1232         },
1233         {
1234                 .ctl_name       = NET_NF_CONNTRACK_TCP_TIMEOUT_MAX_RETRANS,
1235                 .procname       = "nf_conntrack_tcp_timeout_max_retrans",
1236                 .data           = &nf_ct_tcp_timeout_max_retrans,
1237                 .maxlen         = sizeof(unsigned int),
1238                 .mode           = 0644,
1239                 .proc_handler   = &proc_dointvec_jiffies,
1240         },
1241         {
1242                 .ctl_name       = NET_NF_CONNTRACK_TCP_LOOSE,
1243                 .procname       = "nf_conntrack_tcp_loose",
1244                 .data           = &nf_ct_tcp_loose,
1245                 .maxlen         = sizeof(unsigned int),
1246                 .mode           = 0644,
1247                 .proc_handler   = &proc_dointvec,
1248         },
1249         {
1250                 .ctl_name       = NET_NF_CONNTRACK_TCP_BE_LIBERAL,
1251                 .procname       = "nf_conntrack_tcp_be_liberal",
1252                 .data           = &nf_ct_tcp_be_liberal,
1253                 .maxlen         = sizeof(unsigned int),
1254                 .mode           = 0644,
1255                 .proc_handler   = &proc_dointvec,
1256         },
1257         {
1258                 .ctl_name       = NET_NF_CONNTRACK_TCP_MAX_RETRANS,
1259                 .procname       = "nf_conntrack_tcp_max_retrans",
1260                 .data           = &nf_ct_tcp_max_retrans,
1261                 .maxlen         = sizeof(unsigned int),
1262                 .mode           = 0644,
1263                 .proc_handler   = &proc_dointvec,
1264         },
1265         {
1266                 .ctl_name       = 0
1267         }
1268 };
1269
1270 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1271 static struct ctl_table tcp_compat_sysctl_table[] = {
1272         {
1273                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_SYN_SENT,
1274                 .procname       = "ip_conntrack_tcp_timeout_syn_sent",
1275                 .data           = &nf_ct_tcp_timeout_syn_sent,
1276                 .maxlen         = sizeof(unsigned int),
1277                 .mode           = 0644,
1278                 .proc_handler   = &proc_dointvec_jiffies,
1279         },
1280         {
1281                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_SYN_RECV,
1282                 .procname       = "ip_conntrack_tcp_timeout_syn_recv",
1283                 .data           = &nf_ct_tcp_timeout_syn_recv,
1284                 .maxlen         = sizeof(unsigned int),
1285                 .mode           = 0644,
1286                 .proc_handler   = &proc_dointvec_jiffies,
1287         },
1288         {
1289                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_ESTABLISHED,
1290                 .procname       = "ip_conntrack_tcp_timeout_established",
1291                 .data           = &nf_ct_tcp_timeout_established,
1292                 .maxlen         = sizeof(unsigned int),
1293                 .mode           = 0644,
1294                 .proc_handler   = &proc_dointvec_jiffies,
1295         },
1296         {
1297                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_FIN_WAIT,
1298                 .procname       = "ip_conntrack_tcp_timeout_fin_wait",
1299                 .data           = &nf_ct_tcp_timeout_fin_wait,
1300                 .maxlen         = sizeof(unsigned int),
1301                 .mode           = 0644,
1302                 .proc_handler   = &proc_dointvec_jiffies,
1303         },
1304         {
1305                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_CLOSE_WAIT,
1306                 .procname       = "ip_conntrack_tcp_timeout_close_wait",
1307                 .data           = &nf_ct_tcp_timeout_close_wait,
1308                 .maxlen         = sizeof(unsigned int),
1309                 .mode           = 0644,
1310                 .proc_handler   = &proc_dointvec_jiffies,
1311         },
1312         {
1313                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_LAST_ACK,
1314                 .procname       = "ip_conntrack_tcp_timeout_last_ack",
1315                 .data           = &nf_ct_tcp_timeout_last_ack,
1316                 .maxlen         = sizeof(unsigned int),
1317                 .mode           = 0644,
1318                 .proc_handler   = &proc_dointvec_jiffies,
1319         },
1320         {
1321                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_TIME_WAIT,
1322                 .procname       = "ip_conntrack_tcp_timeout_time_wait",
1323                 .data           = &nf_ct_tcp_timeout_time_wait,
1324                 .maxlen         = sizeof(unsigned int),
1325                 .mode           = 0644,
1326                 .proc_handler   = &proc_dointvec_jiffies,
1327         },
1328         {
1329                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_CLOSE,
1330                 .procname       = "ip_conntrack_tcp_timeout_close",
1331                 .data           = &nf_ct_tcp_timeout_close,
1332                 .maxlen         = sizeof(unsigned int),
1333                 .mode           = 0644,
1334                 .proc_handler   = &proc_dointvec_jiffies,
1335         },
1336         {
1337                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_TIMEOUT_MAX_RETRANS,
1338                 .procname       = "ip_conntrack_tcp_timeout_max_retrans",
1339                 .data           = &nf_ct_tcp_timeout_max_retrans,
1340                 .maxlen         = sizeof(unsigned int),
1341                 .mode           = 0644,
1342                 .proc_handler   = &proc_dointvec_jiffies,
1343         },
1344         {
1345                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_LOOSE,
1346                 .procname       = "ip_conntrack_tcp_loose",
1347                 .data           = &nf_ct_tcp_loose,
1348                 .maxlen         = sizeof(unsigned int),
1349                 .mode           = 0644,
1350                 .proc_handler   = &proc_dointvec,
1351         },
1352         {
1353                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_BE_LIBERAL,
1354                 .procname       = "ip_conntrack_tcp_be_liberal",
1355                 .data           = &nf_ct_tcp_be_liberal,
1356                 .maxlen         = sizeof(unsigned int),
1357                 .mode           = 0644,
1358                 .proc_handler   = &proc_dointvec,
1359         },
1360         {
1361                 .ctl_name       = NET_IPV4_NF_CONNTRACK_TCP_MAX_RETRANS,
1362                 .procname       = "ip_conntrack_tcp_max_retrans",
1363                 .data           = &nf_ct_tcp_max_retrans,
1364                 .maxlen         = sizeof(unsigned int),
1365                 .mode           = 0644,
1366                 .proc_handler   = &proc_dointvec,
1367         },
1368         {
1369                 .ctl_name       = 0
1370         }
1371 };
1372 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
1373 #endif /* CONFIG_SYSCTL */
1374
1375 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 __read_mostly =
1376 {
1377         .l3proto                = PF_INET,
1378         .l4proto                = IPPROTO_TCP,
1379         .name                   = "tcp",
1380         .pkt_to_tuple           = tcp_pkt_to_tuple,
1381         .invert_tuple           = tcp_invert_tuple,
1382         .print_tuple            = tcp_print_tuple,
1383         .print_conntrack        = tcp_print_conntrack,
1384         .packet                 = tcp_packet,
1385         .new                    = tcp_new,
1386         .error                  = tcp_error,
1387 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1388         .to_nfattr              = tcp_to_nfattr,
1389         .from_nfattr            = nfattr_to_tcp,
1390         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
1391         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
1392 #endif
1393 #ifdef CONFIG_SYSCTL
1394         .ctl_table_users        = &tcp_sysctl_table_users,
1395         .ctl_table_header       = &tcp_sysctl_header,
1396         .ctl_table              = tcp_sysctl_table,
1397 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1398         .ctl_compat_table       = tcp_compat_sysctl_table,
1399 #endif
1400 #endif
1401 };
1402 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp4);
1403
1404 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp6 __read_mostly =
1405 {
1406         .l3proto                = PF_INET6,
1407         .l4proto                = IPPROTO_TCP,
1408         .name                   = "tcp",
1409         .pkt_to_tuple           = tcp_pkt_to_tuple,
1410         .invert_tuple           = tcp_invert_tuple,
1411         .print_tuple            = tcp_print_tuple,
1412         .print_conntrack        = tcp_print_conntrack,
1413         .packet                 = tcp_packet,
1414         .new                    = tcp_new,
1415         .error                  = tcp_error,
1416 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1417         .to_nfattr              = tcp_to_nfattr,
1418         .from_nfattr            = nfattr_to_tcp,
1419         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
1420         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
1421 #endif
1422 #ifdef CONFIG_SYSCTL
1423         .ctl_table_users        = &tcp_sysctl_table_users,
1424         .ctl_table_header       = &tcp_sysctl_header,
1425         .ctl_table              = tcp_sysctl_table,
1426 #endif
1427 };
1428 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp6);