net/netfilter/nf_conntrack_proto_tcp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* (C) 1999-2001 Paul `Rusty' Russell
   3  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   4  * (C) 2002-2013 Jozsef Kadlecsik <kadlec@netfilter.org>
   5  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   6  */
   7
   8 #include <linux/types.h>
   9 #include <linux/timer.h>
  10 #include <linux/module.h>
  11 #include <linux/in.h>
  12 #include <linux/tcp.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/ipv6.h>
  16 #include <net/ip6_checksum.h>
  17 #include <asm/unaligned.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_conntrack_seqadj.h>
  28 #include <net/netfilter/nf_conntrack_synproxy.h>
  29 #include <net/netfilter/nf_conntrack_timeout.h>
  30 #include <net/netfilter/nf_log.h>
  31 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  32 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  33
  34   /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
  35      closely.  They're more complex. --RR */
  36
  37 static const char *const tcp_conntrack_names[] = {
  38         "NONE",
  39         "SYN_SENT",
  40         "SYN_RECV",
  41         "ESTABLISHED",
  42         "FIN_WAIT",
  43         "CLOSE_WAIT",
  44         "LAST_ACK",
  45         "TIME_WAIT",
  46         "CLOSE",
  47         "SYN_SENT2",
  48 };
  49
  50 #define SECS * HZ
  51 #define MINS * 60 SECS
  52 #define HOURS * 60 MINS
  53 #define DAYS * 24 HOURS
  54
  55 static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
  56         [TCP_CONNTRACK_SYN_SENT]        = 2 MINS,
  57         [TCP_CONNTRACK_SYN_RECV]        = 60 SECS,
  58         [TCP_CONNTRACK_ESTABLISHED]     = 5 DAYS,
  59         [TCP_CONNTRACK_FIN_WAIT]        = 2 MINS,
  60         [TCP_CONNTRACK_CLOSE_WAIT]      = 60 SECS,
  61         [TCP_CONNTRACK_LAST_ACK]        = 30 SECS,
  62         [TCP_CONNTRACK_TIME_WAIT]       = 2 MINS,
  63         [TCP_CONNTRACK_CLOSE]           = 10 SECS,
  64         [TCP_CONNTRACK_SYN_SENT2]       = 2 MINS,
  65 /* RFC1122 says the R2 limit should be at least 100 seconds.
  66    Linux uses 15 packets as limit, which corresponds
  67    to ~13-30min depending on RTO. */
  68         [TCP_CONNTRACK_RETRANS]         = 5 MINS,
  69         [TCP_CONNTRACK_UNACK]           = 5 MINS,
  70 };
  71
  72 #define sNO TCP_CONNTRACK_NONE
  73 #define sSS TCP_CONNTRACK_SYN_SENT
  74 #define sSR TCP_CONNTRACK_SYN_RECV
  75 #define sES TCP_CONNTRACK_ESTABLISHED
  76 #define sFW TCP_CONNTRACK_FIN_WAIT
  77 #define sCW TCP_CONNTRACK_CLOSE_WAIT
  78 #define sLA TCP_CONNTRACK_LAST_ACK
  79 #define sTW TCP_CONNTRACK_TIME_WAIT
  80 #define sCL TCP_CONNTRACK_CLOSE
  81 #define sS2 TCP_CONNTRACK_SYN_SENT2
  82 #define sIV TCP_CONNTRACK_MAX
  83 #define sIG TCP_CONNTRACK_IGNORE
  84
  85 /* What TCP flags are set from RST/SYN/FIN/ACK. */
  86 enum tcp_bit_set {
  87         TCP_SYN_SET,
  88         TCP_SYNACK_SET,
  89         TCP_FIN_SET,
  90         TCP_ACK_SET,
  91         TCP_RST_SET,
  92         TCP_NONE_SET,
  93 };
  94
  95 /*
  96  * The TCP state transition table needs a few words...
  97  *
  98  * We are the man in the middle. All the packets go through us
  99  * but might get lost in transit to the destination.
 100  * It is assumed that the destinations can't receive segments
 101  * we haven't seen.
 102  *
 103  * The checked segment is in window, but our windows are *not*
 104  * equivalent with the ones of the sender/receiver. We always
 105  * try to guess the state of the current sender.
 106  *
 107  * The meaning of the states are:
 108  *
 109  * NONE:        initial state
 110  * SYN_SENT:    SYN-only packet seen
 111  * SYN_SENT2:   SYN-only packet seen from reply dir, simultaneous open
 112  * SYN_RECV:    SYN-ACK packet seen
 113  * ESTABLISHED: ACK packet seen
 114  * FIN_WAIT:    FIN packet seen
 115  * CLOSE_WAIT:  ACK seen (after FIN)
 116  * LAST_ACK:    FIN seen (after FIN)
 117  * TIME_WAIT:   last ACK seen
 118  * CLOSE:       closed connection (RST)
 119  *
 120  * Packets marked as IGNORED (sIG):
 121  *      if they may be either invalid or valid
 122  *      and the receiver may send back a connection
 123  *      closing RST or a SYN/ACK.
 124  *
 125  * Packets marked as INVALID (sIV):
 126  *      if we regard them as truly invalid packets
 127  */
 128 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
 129         {
 130 /* ORIGINAL */
 131 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 132 /*syn*/    { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
 133 /*
 134  *      sNO -> sSS      Initialize a new connection
 135  *      sSS -> sSS      Retransmitted SYN
 136  *      sS2 -> sS2      Late retransmitted SYN
 137  *      sSR -> sIG
 138  *      sES -> sIG      Error: SYNs in window outside the SYN_SENT state
 139  *                      are errors. Receiver will reply with RST
 140  *                      and close the connection.
 141  *                      Or we are not in sync and hold a dead connection.
 142  *      sFW -> sIG
 143  *      sCW -> sIG
 144  *      sLA -> sIG
 145  *      sTW -> sSS      Reopened connection (RFC 1122).
 146  *      sCL -> sSS
 147  */
 148 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 149 /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
 150 /*
 151  *      sNO -> sIV      Too late and no reason to do anything
 152  *      sSS -> sIV      Client can't send SYN and then SYN/ACK
 153  *      sS2 -> sSR      SYN/ACK sent to SYN2 in simultaneous open
 154  *      sSR -> sSR      Late retransmitted SYN/ACK in simultaneous open
 155  *      sES -> sIV      Invalid SYN/ACK packets sent by the client
 156  *      sFW -> sIV
 157  *      sCW -> sIV
 158  *      sLA -> sIV
 159  *      sTW -> sIV
 160  *      sCL -> sIV
 161  */
 162 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 163 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 164 /*
 165  *      sNO -> sIV      Too late and no reason to do anything...
 166  *      sSS -> sIV      Client migth not send FIN in this state:
 167  *                      we enforce waiting for a SYN/ACK reply first.
 168  *      sS2 -> sIV
 169  *      sSR -> sFW      Close started.
 170  *      sES -> sFW
 171  *      sFW -> sLA      FIN seen in both directions, waiting for
 172  *                      the last ACK.
 173  *                      Migth be a retransmitted FIN as well...
 174  *      sCW -> sLA
 175  *      sLA -> sLA      Retransmitted FIN. Remain in the same state.
 176  *      sTW -> sTW
 177  *      sCL -> sCL
 178  */
 179 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 180 /*ack*/    { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 181 /*
 182  *      sNO -> sES      Assumed.
 183  *      sSS -> sIV      ACK is invalid: we haven't seen a SYN/ACK yet.
 184  *      sS2 -> sIV
 185  *      sSR -> sES      Established state is reached.
 186  *      sES -> sES      :-)
 187  *      sFW -> sCW      Normal close request answered by ACK.
 188  *      sCW -> sCW
 189  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 190  *      sTW -> sTW      Retransmitted last ACK. Remain in the same state.
 191  *      sCL -> sCL
 192  */
 193 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 194 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 195 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 196         },
 197         {
 198 /* REPLY */
 199 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 200 /*syn*/    { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
 201 /*
 202  *      sNO -> sIV      Never reached.
 203  *      sSS -> sS2      Simultaneous open
 204  *      sS2 -> sS2      Retransmitted simultaneous SYN
 205  *      sSR -> sIV      Invalid SYN packets sent by the server
 206  *      sES -> sIV
 207  *      sFW -> sIV
 208  *      sCW -> sIV
 209  *      sLA -> sIV
 210  *      sTW -> sSS      Reopened connection, but server may have switched role
 211  *      sCL -> sIV
 212  */
 213 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 214 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
 215 /*
 216  *      sSS -> sSR      Standard open.
 217  *      sS2 -> sSR      Simultaneous open
 218  *      sSR -> sIG      Retransmitted SYN/ACK, ignore it.
 219  *      sES -> sIG      Late retransmitted SYN/ACK?
 220  *      sFW -> sIG      Might be SYN/ACK answering ignored SYN
 221  *      sCW -> sIG
 222  *      sLA -> sIG
 223  *      sTW -> sIG
 224  *      sCL -> sIG
 225  */
 226 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 227 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 228 /*
 229  *      sSS -> sIV      Server might not send FIN in this state.
 230  *      sS2 -> sIV
 231  *      sSR -> sFW      Close started.
 232  *      sES -> sFW
 233  *      sFW -> sLA      FIN seen in both directions.
 234  *      sCW -> sLA
 235  *      sLA -> sLA      Retransmitted FIN.
 236  *      sTW -> sTW
 237  *      sCL -> sCL
 238  */
 239 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 240 /*ack*/    { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
 241 /*
 242  *      sSS -> sIG      Might be a half-open connection.
 243  *      sS2 -> sIG
 244  *      sSR -> sSR      Might answer late resent SYN.
 245  *      sES -> sES      :-)
 246  *      sFW -> sCW      Normal close request answered by ACK.
 247  *      sCW -> sCW
 248  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 249  *      sTW -> sTW      Retransmitted last ACK.
 250  *      sCL -> sCL
 251  */
 252 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 253 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 254 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 255         }
 256 };
 257
 258 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 259 /* Print out the private part of the conntrack. */
 260 static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 261 {
 262         if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
 263                 return;
 264
 265         seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
 266 }
 267 #endif
 268
 269 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
 270 {
 271         if (tcph->rst) return TCP_RST_SET;
 272         else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
 273         else if (tcph->fin) return TCP_FIN_SET;
 274         else if (tcph->ack) return TCP_ACK_SET;
 275         else return TCP_NONE_SET;
 276 }
 277
 278 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
 279    in IP Filter' by Guido van Rooij.
 280
 281    http://www.sane.nl/events/sane2000/papers.html
 282    http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
 283
 284    The boundaries and the conditions are changed according to RFC793:
 285    the packet must intersect the window (i.e. segments may be
 286    after the right or before the left edge) and thus receivers may ACK
 287    segments after the right edge of the window.
 288
 289         td_maxend = max(sack + max(win,1)) seen in reply packets
 290         td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
 291         td_maxwin += seq + len - sender.td_maxend
 292                         if seq + len > sender.td_maxend
 293         td_end    = max(seq + len) seen in sent packets
 294
 295    I.   Upper bound for valid data:     seq <= sender.td_maxend
 296    II.  Lower bound for valid data:     seq + len >= sender.td_end - receiver.td_maxwin
 297    III. Upper bound for valid (s)ack:   sack <= receiver.td_end
 298    IV.  Lower bound for valid (s)ack:   sack >= receiver.td_end - MAXACKWINDOW
 299
 300    where sack is the highest right edge of sack block found in the packet
 301    or ack in the case of packet without SACK option.
 302
 303    The upper bound limit for a valid (s)ack is not ignored -
 304    we doesn't have to deal with fragments.
 305 */
 306
 307 static inline __u32 segment_seq_plus_len(__u32 seq,
 308                                          size_t len,
 309                                          unsigned int dataoff,
 310                                          const struct tcphdr *tcph)
 311 {
 312         /* XXX Should I use payload length field in IP/IPv6 header ?
 313          * - YK */
 314         return (seq + len - dataoff - tcph->doff*4
 315                 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
 316 }
 317
 318 /* Fixme: what about big packets? */
 319 #define MAXACKWINCONST                  66000
 320 #define MAXACKWINDOW(sender)                                            \
 321         ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin     \
 322                                               : MAXACKWINCONST)
 323
 324 /*
 325  * Simplified tcp_parse_options routine from tcp_input.c
 326  */
 327 static void tcp_options(const struct sk_buff *skb,
 328                         unsigned int dataoff,
 329                         const struct tcphdr *tcph,
 330                         struct ip_ct_tcp_state *state)
 331 {
 332         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 333         const unsigned char *ptr;
 334         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 335
 336         if (!length)
 337                 return;
 338
 339         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 340                                  length, buff);
 341         if (!ptr)
 342                 return;
 343
 344         state->td_scale =
 345         state->flags = 0;
 346
 347         while (length > 0) {
 348                 int opcode=*ptr++;
 349                 int opsize;
 350
 351                 switch (opcode) {
 352                 case TCPOPT_EOL:
 353                         return;
 354                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 355                         length--;
 356                         continue;
 357                 default:
 358                         if (length < 2)
 359                                 return;
 360                         opsize=*ptr++;
 361                         if (opsize < 2) /* "silly options" */
 362                                 return;
 363                         if (opsize > length)
 364                                 return; /* don't parse partial options */
 365
 366                         if (opcode == TCPOPT_SACK_PERM
 367                             && opsize == TCPOLEN_SACK_PERM)
 368                                 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
 369                         else if (opcode == TCPOPT_WINDOW
 370                                  && opsize == TCPOLEN_WINDOW) {
 371                                 state->td_scale = *(u_int8_t *)ptr;
 372
 373                                 if (state->td_scale > TCP_MAX_WSCALE)
 374                                         state->td_scale = TCP_MAX_WSCALE;
 375
 376                                 state->flags |=
 377                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 378                         }
 379                         ptr += opsize - 2;
 380                         length -= opsize;
 381                 }
 382         }
 383 }
 384
 385 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
 386                      const struct tcphdr *tcph, __u32 *sack)
 387 {
 388         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 389         const unsigned char *ptr;
 390         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 391         __u32 tmp;
 392
 393         if (!length)
 394                 return;
 395
 396         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 397                                  length, buff);
 398         if (!ptr)
 399                 return;
 400
 401         /* Fast path for timestamp-only option */
 402         if (length == TCPOLEN_TSTAMP_ALIGNED
 403             && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
 404                                        | (TCPOPT_NOP << 16)
 405                                        | (TCPOPT_TIMESTAMP << 8)
 406                                        | TCPOLEN_TIMESTAMP))
 407                 return;
 408
 409         while (length > 0) {
 410                 int opcode = *ptr++;
 411                 int opsize, i;
 412
 413                 switch (opcode) {
 414                 case TCPOPT_EOL:
 415                         return;
 416                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 417                         length--;
 418                         continue;
 419                 default:
 420                         if (length < 2)
 421                                 return;
 422                         opsize = *ptr++;
 423                         if (opsize < 2) /* "silly options" */
 424                                 return;
 425                         if (opsize > length)
 426                                 return; /* don't parse partial options */
 427
 428                         if (opcode == TCPOPT_SACK
 429                             && opsize >= (TCPOLEN_SACK_BASE
 430                                           + TCPOLEN_SACK_PERBLOCK)
 431                             && !((opsize - TCPOLEN_SACK_BASE)
 432                                  % TCPOLEN_SACK_PERBLOCK)) {
 433                                 for (i = 0;
 434                                      i < (opsize - TCPOLEN_SACK_BASE);
 435                                      i += TCPOLEN_SACK_PERBLOCK) {
 436                                         tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
 437
 438                                         if (after(tmp, *sack))
 439                                                 *sack = tmp;
 440                                 }
 441                                 return;
 442                         }
 443                         ptr += opsize - 2;
 444                         length -= opsize;
 445                 }
 446         }
 447 }
 448
 449 static bool tcp_in_window(struct nf_conn *ct,
 450                           enum ip_conntrack_dir dir,
 451                           unsigned int index,
 452                           const struct sk_buff *skb,
 453                           unsigned int dataoff,
 454                           const struct tcphdr *tcph,
 455                           const struct nf_hook_state *hook_state)
 456 {
 457         struct ip_ct_tcp *state = &ct->proto.tcp;
 458         struct net *net = nf_ct_net(ct);
 459         struct nf_tcp_net *tn = nf_tcp_pernet(net);
 460         struct ip_ct_tcp_state *sender = &state->seen[dir];
 461         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 462         const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
 463         __u32 seq, ack, sack, end, win, swin;
 464         u16 win_raw;
 465         s32 receiver_offset;
 466         bool res, in_recv_win;
 467
 468         /*
 469          * Get the required data from the packet.
 470          */
 471         seq = ntohl(tcph->seq);
 472         ack = sack = ntohl(tcph->ack_seq);
 473         win_raw = ntohs(tcph->window);
 474         win = win_raw;
 475         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
 476
 477         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
 478                 tcp_sack(skb, dataoff, tcph, &sack);
 479
 480         /* Take into account NAT sequence number mangling */
 481         receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
 482         ack -= receiver_offset;
 483         sack -= receiver_offset;
 484
 485         pr_debug("tcp_in_window: START\n");
 486         pr_debug("tcp_in_window: ");
 487         nf_ct_dump_tuple(tuple);
 488         pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
 489                  seq, ack, receiver_offset, sack, receiver_offset, win, end);
 490         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 491                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 492                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 493                  sender->td_scale,
 494                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 495                  receiver->td_scale);
 496
 497         if (sender->td_maxwin == 0) {
 498                 /*
 499                  * Initialize sender data.
 500                  */
 501                 if (tcph->syn) {
 502                         /*
 503                          * SYN-ACK in reply to a SYN
 504                          * or SYN from reply direction in simultaneous open.
 505                          */
 506                         sender->td_end =
 507                         sender->td_maxend = end;
 508                         sender->td_maxwin = (win == 0 ? 1 : win);
 509
 510                         tcp_options(skb, dataoff, tcph, sender);
 511                         /*
 512                          * RFC 1323:
 513                          * Both sides must send the Window Scale option
 514                          * to enable window scaling in either direction.
 515                          */
 516                         if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
 517                               && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
 518                                 sender->td_scale =
 519                                 receiver->td_scale = 0;
 520                         if (!tcph->ack)
 521                                 /* Simultaneous open */
 522                                 return true;
 523                 } else {
 524                         /*
 525                          * We are in the middle of a connection,
 526                          * its history is lost for us.
 527                          * Let's try to use the data from the packet.
 528                          */
 529                         sender->td_end = end;
 530                         swin = win << sender->td_scale;
 531                         sender->td_maxwin = (swin == 0 ? 1 : swin);
 532                         sender->td_maxend = end + sender->td_maxwin;
 533                         if (receiver->td_maxwin == 0) {
 534                                 /* We haven't seen traffic in the other
 535                                  * direction yet but we have to tweak window
 536                                  * tracking to pass III and IV until that
 537                                  * happens.
 538                                  */
 539                                 receiver->td_end = receiver->td_maxend = sack;
 540                         } else if (sack == receiver->td_end + 1) {
 541                                 /* Likely a reply to a keepalive.
 542                                  * Needed for III.
 543                                  */
 544                                 receiver->td_end++;
 545                         }
 546
 547                 }
 548         } else if (((state->state == TCP_CONNTRACK_SYN_SENT
 549                      && dir == IP_CT_DIR_ORIGINAL)
 550                    || (state->state == TCP_CONNTRACK_SYN_RECV
 551                      && dir == IP_CT_DIR_REPLY))
 552                    && after(end, sender->td_end)) {
 553                 /*
 554                  * RFC 793: "if a TCP is reinitialized ... then it need
 555                  * not wait at all; it must only be sure to use sequence
 556                  * numbers larger than those recently used."
 557                  */
 558                 sender->td_end =
 559                 sender->td_maxend = end;
 560                 sender->td_maxwin = (win == 0 ? 1 : win);
 561
 562                 tcp_options(skb, dataoff, tcph, sender);
 563         }
 564
 565         if (!(tcph->ack)) {
 566                 /*
 567                  * If there is no ACK, just pretend it was set and OK.
 568                  */
 569                 ack = sack = receiver->td_end;
 570         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
 571                     (TCP_FLAG_ACK|TCP_FLAG_RST))
 572                    && (ack == 0)) {
 573                 /*
 574                  * Broken TCP stacks, that set ACK in RST packets as well
 575                  * with zero ack value.
 576                  */
 577                 ack = sack = receiver->td_end;
 578         }
 579
 580         if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
 581                 /*
 582                  * RST sent answering SYN.
 583                  */
 584                 seq = end = sender->td_end;
 585
 586         pr_debug("tcp_in_window: ");
 587         nf_ct_dump_tuple(tuple);
 588         pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
 589                  seq, ack, receiver_offset, sack, receiver_offset, win, end);
 590         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 591                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 592                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 593                  sender->td_scale,
 594                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 595                  receiver->td_scale);
 596
 597         /* Is the ending sequence in the receive window (if available)? */
 598         in_recv_win = !receiver->td_maxwin ||
 599                       after(end, sender->td_end - receiver->td_maxwin - 1);
 600
 601         pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
 602                  before(seq, sender->td_maxend + 1),
 603                  (in_recv_win ? 1 : 0),
 604                  before(sack, receiver->td_end + 1),
 605                  after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
 606
 607         if (before(seq, sender->td_maxend + 1) &&
 608             in_recv_win &&
 609             before(sack, receiver->td_end + 1) &&
 610             after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
 611                 /*
 612                  * Take into account window scaling (RFC 1323).
 613                  */
 614                 if (!tcph->syn)
 615                         win <<= sender->td_scale;
 616
 617                 /*
 618                  * Update sender data.
 619                  */
 620                 swin = win + (sack - ack);
 621                 if (sender->td_maxwin < swin)
 622                         sender->td_maxwin = swin;
 623                 if (after(end, sender->td_end)) {
 624                         sender->td_end = end;
 625                         sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 626                 }
 627                 if (tcph->ack) {
 628                         if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
 629                                 sender->td_maxack = ack;
 630                                 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
 631                         } else if (after(ack, sender->td_maxack))
 632                                 sender->td_maxack = ack;
 633                 }
 634
 635                 /*
 636                  * Update receiver data.
 637                  */
 638                 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
 639                         receiver->td_maxwin += end - sender->td_maxend;
 640                 if (after(sack + win, receiver->td_maxend - 1)) {
 641                         receiver->td_maxend = sack + win;
 642                         if (win == 0)
 643                                 receiver->td_maxend++;
 644                 }
 645                 if (ack == receiver->td_end)
 646                         receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 647
 648                 /*
 649                  * Check retransmissions.
 650                  */
 651                 if (index == TCP_ACK_SET) {
 652                         if (state->last_dir == dir
 653                             && state->last_seq == seq
 654                             && state->last_ack == ack
 655                             && state->last_end == end
 656                             && state->last_win == win_raw)
 657                                 state->retrans++;
 658                         else {
 659                                 state->last_dir = dir;
 660                                 state->last_seq = seq;
 661                                 state->last_ack = ack;
 662                                 state->last_end = end;
 663                                 state->last_win = win_raw;
 664                                 state->retrans = 0;
 665                         }
 666                 }
 667                 res = true;
 668         } else {
 669                 res = false;
 670                 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
 671                     tn->tcp_be_liberal)
 672                         res = true;
 673                 if (!res) {
 674                         nf_ct_l4proto_log_invalid(skb, ct, hook_state,
 675                         "%s",
 676                         before(seq, sender->td_maxend + 1) ?
 677                         in_recv_win ?
 678                         before(sack, receiver->td_end + 1) ?
 679                         after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
 680                         : "ACK is under the lower bound (possible overly delayed ACK)"
 681                         : "ACK is over the upper bound (ACKed data not seen yet)"
 682                         : "SEQ is under the lower bound (already ACKed data retransmitted)"
 683                         : "SEQ is over the upper bound (over the window of the receiver)");
 684                 }
 685         }
 686
 687         pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
 688                  "receiver end=%u maxend=%u maxwin=%u\n",
 689                  res, sender->td_end, sender->td_maxend, sender->td_maxwin,
 690                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
 691
 692         return res;
 693 }
 694
 695 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
 696 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
 697                                  TCPHDR_URG) + 1] =
 698 {
 699         [TCPHDR_SYN]                            = 1,
 700         [TCPHDR_SYN|TCPHDR_URG]                 = 1,
 701         [TCPHDR_SYN|TCPHDR_ACK]                 = 1,
 702         [TCPHDR_RST]                            = 1,
 703         [TCPHDR_RST|TCPHDR_ACK]                 = 1,
 704         [TCPHDR_FIN|TCPHDR_ACK]                 = 1,
 705         [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG]      = 1,
 706         [TCPHDR_ACK]                            = 1,
 707         [TCPHDR_ACK|TCPHDR_URG]                 = 1,
 708 };
 709
 710 static void tcp_error_log(const struct sk_buff *skb,
 711                           const struct nf_hook_state *state,
 712                           const char *msg)
 713 {
 714         nf_l4proto_log_invalid(skb, state, IPPROTO_TCP, "%s", msg);
 715 }
 716
 717 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
 718 static bool tcp_error(const struct tcphdr *th,
 719                       struct sk_buff *skb,
 720                       unsigned int dataoff,
 721                       const struct nf_hook_state *state)
 722 {
 723         unsigned int tcplen = skb->len - dataoff;
 724         u8 tcpflags;
 725
 726         /* Not whole TCP header or malformed packet */
 727         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
 728                 tcp_error_log(skb, state, "truncated packet");
 729                 return true;
 730         }
 731
 732         /* Checksum invalid? Ignore.
 733          * We skip checking packets on the outgoing path
 734          * because the checksum is assumed to be correct.
 735          */
 736         /* FIXME: Source route IP option packets --RR */
 737         if (state->net->ct.sysctl_checksum &&
 738             state->hook == NF_INET_PRE_ROUTING &&
 739             nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
 740                 tcp_error_log(skb, state, "bad checksum");
 741                 return true;
 742         }
 743
 744         /* Check TCP flags. */
 745         tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
 746         if (!tcp_valid_flags[tcpflags]) {
 747                 tcp_error_log(skb, state, "invalid tcp flag combination");
 748                 return true;
 749         }
 750
 751         return false;
 752 }
 753
 754 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
 755                              unsigned int dataoff,
 756                              const struct tcphdr *th)
 757 {
 758         enum tcp_conntrack new_state;
 759         struct net *net = nf_ct_net(ct);
 760         const struct nf_tcp_net *tn = nf_tcp_pernet(net);
 761         const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
 762         const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
 763
 764         /* Don't need lock here: this conntrack not in circulation yet */
 765         new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
 766
 767         /* Invalid: delete conntrack */
 768         if (new_state >= TCP_CONNTRACK_MAX) {
 769                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
 770                 return false;
 771         }
 772
 773         if (new_state == TCP_CONNTRACK_SYN_SENT) {
 774                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 775                 /* SYN packet */
 776                 ct->proto.tcp.seen[0].td_end =
 777                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 778                                              dataoff, th);
 779                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 780                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 781                         ct->proto.tcp.seen[0].td_maxwin = 1;
 782                 ct->proto.tcp.seen[0].td_maxend =
 783                         ct->proto.tcp.seen[0].td_end;
 784
 785                 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
 786         } else if (tn->tcp_loose == 0) {
 787                 /* Don't try to pick up connections. */
 788                 return false;
 789         } else {
 790                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 791                 /*
 792                  * We are in the middle of a connection,
 793                  * its history is lost for us.
 794                  * Let's try to use the data from the packet.
 795                  */
 796                 ct->proto.tcp.seen[0].td_end =
 797                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 798                                              dataoff, th);
 799                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 800                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 801                         ct->proto.tcp.seen[0].td_maxwin = 1;
 802                 ct->proto.tcp.seen[0].td_maxend =
 803                         ct->proto.tcp.seen[0].td_end +
 804                         ct->proto.tcp.seen[0].td_maxwin;
 805
 806                 /* We assume SACK and liberal window checking to handle
 807                  * window scaling */
 808                 ct->proto.tcp.seen[0].flags =
 809                 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
 810                                               IP_CT_TCP_FLAG_BE_LIBERAL;
 811         }
 812
 813         /* tcp_packet will set them */
 814         ct->proto.tcp.last_index = TCP_NONE_SET;
 815
 816         pr_debug("%s: sender end=%u maxend=%u maxwin=%u scale=%i "
 817                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 818                  __func__,
 819                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 820                  sender->td_scale,
 821                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 822                  receiver->td_scale);
 823         return true;
 824 }
 825
 826 static bool tcp_can_early_drop(const struct nf_conn *ct)
 827 {
 828         switch (ct->proto.tcp.state) {
 829         case TCP_CONNTRACK_FIN_WAIT:
 830         case TCP_CONNTRACK_LAST_ACK:
 831         case TCP_CONNTRACK_TIME_WAIT:
 832         case TCP_CONNTRACK_CLOSE:
 833         case TCP_CONNTRACK_CLOSE_WAIT:
 834                 return true;
 835         default:
 836                 break;
 837         }
 838
 839         return false;
 840 }
 841
 842 /* Returns verdict for packet, or -1 for invalid. */
 843 int nf_conntrack_tcp_packet(struct nf_conn *ct,
 844                             struct sk_buff *skb,
 845                             unsigned int dataoff,
 846                             enum ip_conntrack_info ctinfo,
 847                             const struct nf_hook_state *state)
 848 {
 849         struct net *net = nf_ct_net(ct);
 850         struct nf_tcp_net *tn = nf_tcp_pernet(net);
 851         struct nf_conntrack_tuple *tuple;
 852         enum tcp_conntrack new_state, old_state;
 853         unsigned int index, *timeouts;
 854         enum ip_conntrack_dir dir;
 855         const struct tcphdr *th;
 856         struct tcphdr _tcph;
 857         unsigned long timeout;
 858
 859         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 860         if (th == NULL)
 861                 return -NF_ACCEPT;
 862
 863         if (tcp_error(th, skb, dataoff, state))
 864                 return -NF_ACCEPT;
 865
 866         if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
 867                 return -NF_ACCEPT;
 868
 869         spin_lock_bh(&ct->lock);
 870         old_state = ct->proto.tcp.state;
 871         dir = CTINFO2DIR(ctinfo);
 872         index = get_conntrack_index(th);
 873         new_state = tcp_conntracks[dir][index][old_state];
 874         tuple = &ct->tuplehash[dir].tuple;
 875
 876         switch (new_state) {
 877         case TCP_CONNTRACK_SYN_SENT:
 878                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 879                         break;
 880                 /* RFC 1122: "When a connection is closed actively,
 881                  * it MUST linger in TIME-WAIT state for a time 2xMSL
 882                  * (Maximum Segment Lifetime). However, it MAY accept
 883                  * a new SYN from the remote TCP to reopen the connection
 884                  * directly from TIME-WAIT state, if..."
 885                  * We ignore the conditions because we are in the
 886                  * TIME-WAIT state anyway.
 887                  *
 888                  * Handle aborted connections: we and the server
 889                  * think there is an existing connection but the client
 890                  * aborts it and starts a new one.
 891                  */
 892                 if (((ct->proto.tcp.seen[dir].flags
 893                       | ct->proto.tcp.seen[!dir].flags)
 894                      & IP_CT_TCP_FLAG_CLOSE_INIT)
 895                     || (ct->proto.tcp.last_dir == dir
 896                         && ct->proto.tcp.last_index == TCP_RST_SET)) {
 897                         /* Attempt to reopen a closed/aborted connection.
 898                          * Delete this connection and look up again. */
 899                         spin_unlock_bh(&ct->lock);
 900
 901                         /* Only repeat if we can actually remove the timer.
 902                          * Destruction may already be in progress in process
 903                          * context and we must give it a chance to terminate.
 904                          */
 905                         if (nf_ct_kill(ct))
 906                                 return -NF_REPEAT;
 907                         return NF_DROP;
 908                 }
 909                 fallthrough;
 910         case TCP_CONNTRACK_IGNORE:
 911                 /* Ignored packets:
 912                  *
 913                  * Our connection entry may be out of sync, so ignore
 914                  * packets which may signal the real connection between
 915                  * the client and the server.
 916                  *
 917                  * a) SYN in ORIGINAL
 918                  * b) SYN/ACK in REPLY
 919                  * c) ACK in reply direction after initial SYN in original.
 920                  *
 921                  * If the ignored packet is invalid, the receiver will send
 922                  * a RST we'll catch below.
 923                  */
 924                 if (index == TCP_SYNACK_SET
 925                     && ct->proto.tcp.last_index == TCP_SYN_SET
 926                     && ct->proto.tcp.last_dir != dir
 927                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
 928                         /* b) This SYN/ACK acknowledges a SYN that we earlier
 929                          * ignored as invalid. This means that the client and
 930                          * the server are both in sync, while the firewall is
 931                          * not. We get in sync from the previously annotated
 932                          * values.
 933                          */
 934                         old_state = TCP_CONNTRACK_SYN_SENT;
 935                         new_state = TCP_CONNTRACK_SYN_RECV;
 936                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
 937                                 ct->proto.tcp.last_end;
 938                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
 939                                 ct->proto.tcp.last_end;
 940                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
 941                                 ct->proto.tcp.last_win == 0 ?
 942                                         1 : ct->proto.tcp.last_win;
 943                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
 944                                 ct->proto.tcp.last_wscale;
 945                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
 946                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
 947                                 ct->proto.tcp.last_flags;
 948                         memset(&ct->proto.tcp.seen[dir], 0,
 949                                sizeof(struct ip_ct_tcp_state));
 950                         break;
 951                 }
 952                 ct->proto.tcp.last_index = index;
 953                 ct->proto.tcp.last_dir = dir;
 954                 ct->proto.tcp.last_seq = ntohl(th->seq);
 955                 ct->proto.tcp.last_end =
 956                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
 957                 ct->proto.tcp.last_win = ntohs(th->window);
 958
 959                 /* a) This is a SYN in ORIGINAL. The client and the server
 960                  * may be in sync but we are not. In that case, we annotate
 961                  * the TCP options and let the packet go through. If it is a
 962                  * valid SYN packet, the server will reply with a SYN/ACK, and
 963                  * then we'll get in sync. Otherwise, the server potentially
 964                  * responds with a challenge ACK if implementing RFC5961.
 965                  */
 966                 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
 967                         struct ip_ct_tcp_state seen = {};
 968
 969                         ct->proto.tcp.last_flags =
 970                         ct->proto.tcp.last_wscale = 0;
 971                         tcp_options(skb, dataoff, th, &seen);
 972                         if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
 973                                 ct->proto.tcp.last_flags |=
 974                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 975                                 ct->proto.tcp.last_wscale = seen.td_scale;
 976                         }
 977                         if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
 978                                 ct->proto.tcp.last_flags |=
 979                                         IP_CT_TCP_FLAG_SACK_PERM;
 980                         }
 981                         /* Mark the potential for RFC5961 challenge ACK,
 982                          * this pose a special problem for LAST_ACK state
 983                          * as ACK is intrepretated as ACKing last FIN.
 984                          */
 985                         if (old_state == TCP_CONNTRACK_LAST_ACK)
 986                                 ct->proto.tcp.last_flags |=
 987                                         IP_CT_EXP_CHALLENGE_ACK;
 988                 }
 989                 spin_unlock_bh(&ct->lock);
 990                 nf_ct_l4proto_log_invalid(skb, ct, state,
 991                                           "packet (index %d) in dir %d ignored, state %s",
 992                                           index, dir,
 993                                           tcp_conntrack_names[old_state]);
 994                 return NF_ACCEPT;
 995         case TCP_CONNTRACK_MAX:
 996                 /* Special case for SYN proxy: when the SYN to the server or
 997                  * the SYN/ACK from the server is lost, the client may transmit
 998                  * a keep-alive packet while in SYN_SENT state. This needs to
 999                  * be associated with the original conntrack entry in order to
1000                  * generate a new SYN with the correct sequence number.
1001                  */
1002                 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
1003                     index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
1004                     ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1005                     ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1006                         pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1007                         spin_unlock_bh(&ct->lock);
1008                         return NF_ACCEPT;
1009                 }
1010
1011                 /* Invalid packet */
1012                 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
1013                          dir, get_conntrack_index(th), old_state);
1014                 spin_unlock_bh(&ct->lock);
1015                 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid state");
1016                 return -NF_ACCEPT;
1017         case TCP_CONNTRACK_TIME_WAIT:
1018                 /* RFC5961 compliance cause stack to send "challenge-ACK"
1019                  * e.g. in response to spurious SYNs.  Conntrack MUST
1020                  * not believe this ACK is acking last FIN.
1021                  */
1022                 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1023                     index == TCP_ACK_SET &&
1024                     ct->proto.tcp.last_dir != dir &&
1025                     ct->proto.tcp.last_index == TCP_SYN_SET &&
1026                     (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1027                         /* Detected RFC5961 challenge ACK */
1028                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1029                         spin_unlock_bh(&ct->lock);
1030                         nf_ct_l4proto_log_invalid(skb, ct, state, "challenge-ack ignored");
1031                         return NF_ACCEPT; /* Don't change state */
1032                 }
1033                 break;
1034         case TCP_CONNTRACK_SYN_SENT2:
1035                 /* tcp_conntracks table is not smart enough to handle
1036                  * simultaneous open.
1037                  */
1038                 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1039                 break;
1040         case TCP_CONNTRACK_SYN_RECV:
1041                 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1042                     ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1043                         new_state = TCP_CONNTRACK_ESTABLISHED;
1044                 break;
1045         case TCP_CONNTRACK_CLOSE:
1046                 if (index != TCP_RST_SET)
1047                         break;
1048
1049                 /* If we are closing, tuple might have been re-used already.
1050                  * last_index, last_ack, and all other ct fields used for
1051                  * sequence/window validation are outdated in that case.
1052                  *
1053                  * As the conntrack can already be expired by GC under pressure,
1054                  * just skip validation checks.
1055                  */
1056                 if (tcp_can_early_drop(ct))
1057                         goto in_window;
1058
1059                 /* td_maxack might be outdated if we let a SYN through earlier */
1060                 if ((ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) &&
1061                     ct->proto.tcp.last_index != TCP_SYN_SET) {
1062                         u32 seq = ntohl(th->seq);
1063
1064                         /* If we are not in established state and SEQ=0 this is most
1065                          * likely an answer to a SYN we let go through above (last_index
1066                          * can be updated due to out-of-order ACKs).
1067                          */
1068                         if (seq == 0 && !nf_conntrack_tcp_established(ct))
1069                                 break;
1070
1071                         if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
1072                                 /* Invalid RST  */
1073                                 spin_unlock_bh(&ct->lock);
1074                                 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid rst");
1075                                 return -NF_ACCEPT;
1076                         }
1077
1078                         if (!nf_conntrack_tcp_established(ct) ||
1079                             seq == ct->proto.tcp.seen[!dir].td_maxack)
1080                                 break;
1081
1082                         /* Check if rst is part of train, such as
1083                          *   foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1084                          *   foo:80 > bar:4379: R, 235946602:235946602(0)  ack 42
1085                          */
1086                         if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1087                             ct->proto.tcp.last_dir == dir &&
1088                             seq == ct->proto.tcp.last_end)
1089                                 break;
1090
1091                         /* ... RST sequence number doesn't match exactly, keep
1092                          * established state to allow a possible challenge ACK.
1093                          */
1094                         new_state = old_state;
1095                 }
1096                 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1097                          && ct->proto.tcp.last_index == TCP_SYN_SET)
1098                         || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1099                             && ct->proto.tcp.last_index == TCP_ACK_SET))
1100                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1101                         /* RST sent to invalid SYN or ACK we had let through
1102                          * at a) and c) above:
1103                          *
1104                          * a) SYN was in window then
1105                          * c) we hold a half-open connection.
1106                          *
1107                          * Delete our connection entry.
1108                          * We skip window checking, because packet might ACK
1109                          * segments we ignored. */
1110                         goto in_window;
1111                 }
1112                 break;
1113         default:
1114                 /* Keep compilers happy. */
1115                 break;
1116         }
1117
1118         if (!tcp_in_window(ct, dir, index,
1119                            skb, dataoff, th, state)) {
1120                 spin_unlock_bh(&ct->lock);
1121                 return -NF_ACCEPT;
1122         }
1123      in_window:
1124         /* From now on we have got in-window packets */
1125         ct->proto.tcp.last_index = index;
1126         ct->proto.tcp.last_dir = dir;
1127
1128         pr_debug("tcp_conntracks: ");
1129         nf_ct_dump_tuple(tuple);
1130         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1131                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1132                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1133                  old_state, new_state);
1134
1135         ct->proto.tcp.state = new_state;
1136         if (old_state != new_state
1137             && new_state == TCP_CONNTRACK_FIN_WAIT)
1138                 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1139
1140         timeouts = nf_ct_timeout_lookup(ct);
1141         if (!timeouts)
1142                 timeouts = tn->timeouts;
1143
1144         if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1145             timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1146                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1147         else if (unlikely(index == TCP_RST_SET))
1148                 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1149         else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1150                  IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1151                  timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1152                 timeout = timeouts[TCP_CONNTRACK_UNACK];
1153         else if (ct->proto.tcp.last_win == 0 &&
1154                  timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1155                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1156         else
1157                 timeout = timeouts[new_state];
1158         spin_unlock_bh(&ct->lock);
1159
1160         if (new_state != old_state)
1161                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1162
1163         if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1164                 /* If only reply is a RST, we can consider ourselves not to
1165                    have an established connection: this is a fairly common
1166                    problem case, so we can delete the conntrack
1167                    immediately.  --RR */
1168                 if (th->rst) {
1169                         nf_ct_kill_acct(ct, ctinfo, skb);
1170                         return NF_ACCEPT;
1171                 }
1172
1173                 if (index == TCP_SYN_SET && old_state == TCP_CONNTRACK_SYN_SENT) {
1174                         /* do not renew timeout on SYN retransmit.
1175                          *
1176                          * Else port reuse by client or NAT middlebox can keep
1177                          * entry alive indefinitely (including nat info).
1178                          */
1179                         return NF_ACCEPT;
1180                 }
1181
1182                 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1183                  * pickup with loose=1. Avoid large ESTABLISHED timeout.
1184                  */
1185                 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1186                     timeout > timeouts[TCP_CONNTRACK_UNACK])
1187                         timeout = timeouts[TCP_CONNTRACK_UNACK];
1188         } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1189                    && (old_state == TCP_CONNTRACK_SYN_RECV
1190                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1191                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1192                 /* Set ASSURED if we see valid ack in ESTABLISHED
1193                    after SYN_RECV or a valid answer for a picked up
1194                    connection. */
1195                 set_bit(IPS_ASSURED_BIT, &ct->status);
1196                 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1197         }
1198         nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1199
1200         return NF_ACCEPT;
1201 }
1202
1203 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1204
1205 #include <linux/netfilter/nfnetlink.h>
1206 #include <linux/netfilter/nfnetlink_conntrack.h>
1207
1208 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1209                          struct nf_conn *ct, bool destroy)
1210 {
1211         struct nlattr *nest_parms;
1212         struct nf_ct_tcp_flags tmp = {};
1213
1214         spin_lock_bh(&ct->lock);
1215         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1216         if (!nest_parms)
1217                 goto nla_put_failure;
1218
1219         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1220                 goto nla_put_failure;
1221
1222         if (destroy)
1223                 goto skip_state;
1224
1225         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1226                        ct->proto.tcp.seen[0].td_scale) ||
1227             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1228                        ct->proto.tcp.seen[1].td_scale))
1229                 goto nla_put_failure;
1230
1231         tmp.flags = ct->proto.tcp.seen[0].flags;
1232         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1233                     sizeof(struct nf_ct_tcp_flags), &tmp))
1234                 goto nla_put_failure;
1235
1236         tmp.flags = ct->proto.tcp.seen[1].flags;
1237         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1238                     sizeof(struct nf_ct_tcp_flags), &tmp))
1239                 goto nla_put_failure;
1240 skip_state:
1241         spin_unlock_bh(&ct->lock);
1242         nla_nest_end(skb, nest_parms);
1243
1244         return 0;
1245
1246 nla_put_failure:
1247         spin_unlock_bh(&ct->lock);
1248         return -1;
1249 }
1250
1251 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1252         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1253         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1254         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1255         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1256         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len = sizeof(struct nf_ct_tcp_flags) },
1257 };
1258
1259 #define TCP_NLATTR_SIZE ( \
1260         NLA_ALIGN(NLA_HDRLEN + 1) + \
1261         NLA_ALIGN(NLA_HDRLEN + 1) + \
1262         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1263         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1264
1265 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1266 {
1267         struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1268         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1269         int err;
1270
1271         /* updates could not contain anything about the private
1272          * protocol info, in that case skip the parsing */
1273         if (!pattr)
1274                 return 0;
1275
1276         err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1277                                           tcp_nla_policy, NULL);
1278         if (err < 0)
1279                 return err;
1280
1281         if (tb[CTA_PROTOINFO_TCP_STATE] &&
1282             nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1283                 return -EINVAL;
1284
1285         spin_lock_bh(&ct->lock);
1286         if (tb[CTA_PROTOINFO_TCP_STATE])
1287                 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1288
1289         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1290                 struct nf_ct_tcp_flags *attr =
1291                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1292                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1293                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1294         }
1295
1296         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1297                 struct nf_ct_tcp_flags *attr =
1298                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1299                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1300                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1301         }
1302
1303         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1304             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1305             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1306             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1307                 ct->proto.tcp.seen[0].td_scale =
1308                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1309                 ct->proto.tcp.seen[1].td_scale =
1310                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1311         }
1312         spin_unlock_bh(&ct->lock);
1313
1314         return 0;
1315 }
1316
1317 static unsigned int tcp_nlattr_tuple_size(void)
1318 {
1319         static unsigned int size __read_mostly;
1320
1321         if (!size)
1322                 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1323
1324         return size;
1325 }
1326 #endif
1327
1328 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1329
1330 #include <linux/netfilter/nfnetlink.h>
1331 #include <linux/netfilter/nfnetlink_cttimeout.h>
1332
1333 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1334                                      struct net *net, void *data)
1335 {
1336         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1337         unsigned int *timeouts = data;
1338         int i;
1339
1340         if (!timeouts)
1341                 timeouts = tn->timeouts;
1342         /* set default TCP timeouts. */
1343         for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1344                 timeouts[i] = tn->timeouts[i];
1345
1346         if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1347                 timeouts[TCP_CONNTRACK_SYN_SENT] =
1348                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1349         }
1350
1351         if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1352                 timeouts[TCP_CONNTRACK_SYN_RECV] =
1353                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1354         }
1355         if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1356                 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1357                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1358         }
1359         if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1360                 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1361                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1362         }
1363         if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1364                 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1365                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1366         }
1367         if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1368                 timeouts[TCP_CONNTRACK_LAST_ACK] =
1369                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1370         }
1371         if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1372                 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1373                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1374         }
1375         if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1376                 timeouts[TCP_CONNTRACK_CLOSE] =
1377                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1378         }
1379         if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1380                 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1381                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1382         }
1383         if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1384                 timeouts[TCP_CONNTRACK_RETRANS] =
1385                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1386         }
1387         if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1388                 timeouts[TCP_CONNTRACK_UNACK] =
1389                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1390         }
1391
1392         timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1393         return 0;
1394 }
1395
1396 static int
1397 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1398 {
1399         const unsigned int *timeouts = data;
1400
1401         if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1402                         htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1403             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1404                          htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1405             nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1406                          htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1407             nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1408                          htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1409             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1410                          htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1411             nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1412                          htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1413             nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1414                          htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1415             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1416                          htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1417             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1418                          htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1419             nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1420                          htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1421             nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1422                          htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1423                 goto nla_put_failure;
1424         return 0;
1425
1426 nla_put_failure:
1427         return -ENOSPC;
1428 }
1429
1430 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1431         [CTA_TIMEOUT_TCP_SYN_SENT]      = { .type = NLA_U32 },
1432         [CTA_TIMEOUT_TCP_SYN_RECV]      = { .type = NLA_U32 },
1433         [CTA_TIMEOUT_TCP_ESTABLISHED]   = { .type = NLA_U32 },
1434         [CTA_TIMEOUT_TCP_FIN_WAIT]      = { .type = NLA_U32 },
1435         [CTA_TIMEOUT_TCP_CLOSE_WAIT]    = { .type = NLA_U32 },
1436         [CTA_TIMEOUT_TCP_LAST_ACK]      = { .type = NLA_U32 },
1437         [CTA_TIMEOUT_TCP_TIME_WAIT]     = { .type = NLA_U32 },
1438         [CTA_TIMEOUT_TCP_CLOSE]         = { .type = NLA_U32 },
1439         [CTA_TIMEOUT_TCP_SYN_SENT2]     = { .type = NLA_U32 },
1440         [CTA_TIMEOUT_TCP_RETRANS]       = { .type = NLA_U32 },
1441         [CTA_TIMEOUT_TCP_UNACK]         = { .type = NLA_U32 },
1442 };
1443 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1444
1445 void nf_conntrack_tcp_init_net(struct net *net)
1446 {
1447         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1448         int i;
1449
1450         for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1451                 tn->timeouts[i] = tcp_timeouts[i];
1452
1453         /* timeouts[0] is unused, make it same as SYN_SENT so
1454          * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1455          */
1456         tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1457
1458         /* If it is set to zero, we disable picking up already established
1459          * connections.
1460          */
1461         tn->tcp_loose = 1;
1462
1463         /* "Be conservative in what you do,
1464          *  be liberal in what you accept from others."
1465          * If it's non-zero, we mark only out of window RST segments as INVALID.
1466          */
1467         tn->tcp_be_liberal = 0;
1468
1469         /* Max number of the retransmitted packets without receiving an (acceptable)
1470          * ACK from the destination. If this number is reached, a shorter timer
1471          * will be started.
1472          */
1473         tn->tcp_max_retrans = 3;
1474
1475 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
1476         tn->offload_timeout = 30 * HZ;
1477         tn->offload_pickup = 120 * HZ;
1478 #endif
1479 }
1480
1481 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1482 {
1483         .l4proto                = IPPROTO_TCP,
1484 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1485         .print_conntrack        = tcp_print_conntrack,
1486 #endif
1487         .can_early_drop         = tcp_can_early_drop,
1488 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1489         .to_nlattr              = tcp_to_nlattr,
1490         .from_nlattr            = nlattr_to_tcp,
1491         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1492         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1493         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1494         .nlattr_size            = TCP_NLATTR_SIZE,
1495         .nla_policy             = nf_ct_port_nla_policy,
1496 #endif
1497 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1498         .ctnl_timeout           = {
1499                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1500                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1501                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1502                 .obj_size       = sizeof(unsigned int) *
1503                                         TCP_CONNTRACK_TIMEOUT_MAX,
1504                 .nla_policy     = tcp_timeout_nla_policy,
1505         },
1506 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1507 };