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 enum nf_ct_tcp_action {
  51         NFCT_TCP_IGNORE,
  52         NFCT_TCP_INVALID,
  53         NFCT_TCP_ACCEPT,
  54 };
  55
  56 #define SECS * HZ
  57 #define MINS * 60 SECS
  58 #define HOURS * 60 MINS
  59 #define DAYS * 24 HOURS
  60
  61 static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
  62         [TCP_CONNTRACK_SYN_SENT]        = 2 MINS,
  63         [TCP_CONNTRACK_SYN_RECV]        = 60 SECS,
  64         [TCP_CONNTRACK_ESTABLISHED]     = 5 DAYS,
  65         [TCP_CONNTRACK_FIN_WAIT]        = 2 MINS,
  66         [TCP_CONNTRACK_CLOSE_WAIT]      = 60 SECS,
  67         [TCP_CONNTRACK_LAST_ACK]        = 30 SECS,
  68         [TCP_CONNTRACK_TIME_WAIT]       = 2 MINS,
  69         [TCP_CONNTRACK_CLOSE]           = 10 SECS,
  70         [TCP_CONNTRACK_SYN_SENT2]       = 2 MINS,
  71 /* RFC1122 says the R2 limit should be at least 100 seconds.
  72    Linux uses 15 packets as limit, which corresponds
  73    to ~13-30min depending on RTO. */
  74         [TCP_CONNTRACK_RETRANS]         = 5 MINS,
  75         [TCP_CONNTRACK_UNACK]           = 5 MINS,
  76 };
  77
  78 #define sNO TCP_CONNTRACK_NONE
  79 #define sSS TCP_CONNTRACK_SYN_SENT
  80 #define sSR TCP_CONNTRACK_SYN_RECV
  81 #define sES TCP_CONNTRACK_ESTABLISHED
  82 #define sFW TCP_CONNTRACK_FIN_WAIT
  83 #define sCW TCP_CONNTRACK_CLOSE_WAIT
  84 #define sLA TCP_CONNTRACK_LAST_ACK
  85 #define sTW TCP_CONNTRACK_TIME_WAIT
  86 #define sCL TCP_CONNTRACK_CLOSE
  87 #define sS2 TCP_CONNTRACK_SYN_SENT2
  88 #define sIV TCP_CONNTRACK_MAX
  89 #define sIG TCP_CONNTRACK_IGNORE
  90
  91 /* What TCP flags are set from RST/SYN/FIN/ACK. */
  92 enum tcp_bit_set {
  93         TCP_SYN_SET,
  94         TCP_SYNACK_SET,
  95         TCP_FIN_SET,
  96         TCP_ACK_SET,
  97         TCP_RST_SET,
  98         TCP_NONE_SET,
  99 };
 100
 101 /*
 102  * The TCP state transition table needs a few words...
 103  *
 104  * We are the man in the middle. All the packets go through us
 105  * but might get lost in transit to the destination.
 106  * It is assumed that the destinations can't receive segments
 107  * we haven't seen.
 108  *
 109  * The checked segment is in window, but our windows are *not*
 110  * equivalent with the ones of the sender/receiver. We always
 111  * try to guess the state of the current sender.
 112  *
 113  * The meaning of the states are:
 114  *
 115  * NONE:        initial state
 116  * SYN_SENT:    SYN-only packet seen
 117  * SYN_SENT2:   SYN-only packet seen from reply dir, simultaneous open
 118  * SYN_RECV:    SYN-ACK packet seen
 119  * ESTABLISHED: ACK packet seen
 120  * FIN_WAIT:    FIN packet seen
 121  * CLOSE_WAIT:  ACK seen (after FIN)
 122  * LAST_ACK:    FIN seen (after FIN)
 123  * TIME_WAIT:   last ACK seen
 124  * CLOSE:       closed connection (RST)
 125  *
 126  * Packets marked as IGNORED (sIG):
 127  *      if they may be either invalid or valid
 128  *      and the receiver may send back a connection
 129  *      closing RST or a SYN/ACK.
 130  *
 131  * Packets marked as INVALID (sIV):
 132  *      if we regard them as truly invalid packets
 133  */
 134 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
 135         {
 136 /* ORIGINAL */
 137 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 138 /*syn*/    { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
 139 /*
 140  *      sNO -> sSS      Initialize a new connection
 141  *      sSS -> sSS      Retransmitted SYN
 142  *      sS2 -> sS2      Late retransmitted SYN
 143  *      sSR -> sIG
 144  *      sES -> sIG      Error: SYNs in window outside the SYN_SENT state
 145  *                      are errors. Receiver will reply with RST
 146  *                      and close the connection.
 147  *                      Or we are not in sync and hold a dead connection.
 148  *      sFW -> sIG
 149  *      sCW -> sIG
 150  *      sLA -> sIG
 151  *      sTW -> sSS      Reopened connection (RFC 1122).
 152  *      sCL -> sSS
 153  */
 154 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 155 /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
 156 /*
 157  *      sNO -> sIV      Too late and no reason to do anything
 158  *      sSS -> sIV      Client can't send SYN and then SYN/ACK
 159  *      sS2 -> sSR      SYN/ACK sent to SYN2 in simultaneous open
 160  *      sSR -> sSR      Late retransmitted SYN/ACK in simultaneous open
 161  *      sES -> sIV      Invalid SYN/ACK packets sent by the client
 162  *      sFW -> sIV
 163  *      sCW -> sIV
 164  *      sLA -> sIV
 165  *      sTW -> sIV
 166  *      sCL -> sIV
 167  */
 168 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 169 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 170 /*
 171  *      sNO -> sIV      Too late and no reason to do anything...
 172  *      sSS -> sIV      Client migth not send FIN in this state:
 173  *                      we enforce waiting for a SYN/ACK reply first.
 174  *      sS2 -> sIV
 175  *      sSR -> sFW      Close started.
 176  *      sES -> sFW
 177  *      sFW -> sLA      FIN seen in both directions, waiting for
 178  *                      the last ACK.
 179  *                      Migth be a retransmitted FIN as well...
 180  *      sCW -> sLA
 181  *      sLA -> sLA      Retransmitted FIN. Remain in the same state.
 182  *      sTW -> sTW
 183  *      sCL -> sCL
 184  */
 185 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 186 /*ack*/    { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 187 /*
 188  *      sNO -> sES      Assumed.
 189  *      sSS -> sIV      ACK is invalid: we haven't seen a SYN/ACK yet.
 190  *      sS2 -> sIV
 191  *      sSR -> sES      Established state is reached.
 192  *      sES -> sES      :-)
 193  *      sFW -> sCW      Normal close request answered by ACK.
 194  *      sCW -> sCW
 195  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 196  *      sTW -> sTW      Retransmitted last ACK. Remain in the same state.
 197  *      sCL -> sCL
 198  */
 199 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 200 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 201 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 202         },
 203         {
 204 /* REPLY */
 205 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 206 /*syn*/    { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
 207 /*
 208  *      sNO -> sIV      Never reached.
 209  *      sSS -> sS2      Simultaneous open
 210  *      sS2 -> sS2      Retransmitted simultaneous SYN
 211  *      sSR -> sIV      Invalid SYN packets sent by the server
 212  *      sES -> sIV
 213  *      sFW -> sIV
 214  *      sCW -> sIV
 215  *      sLA -> sIV
 216  *      sTW -> sSS      Reopened connection, but server may have switched role
 217  *      sCL -> sIV
 218  */
 219 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 220 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
 221 /*
 222  *      sSS -> sSR      Standard open.
 223  *      sS2 -> sSR      Simultaneous open
 224  *      sSR -> sIG      Retransmitted SYN/ACK, ignore it.
 225  *      sES -> sIG      Late retransmitted SYN/ACK?
 226  *      sFW -> sIG      Might be SYN/ACK answering ignored SYN
 227  *      sCW -> sIG
 228  *      sLA -> sIG
 229  *      sTW -> sIG
 230  *      sCL -> sIG
 231  */
 232 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 233 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 234 /*
 235  *      sSS -> sIV      Server might not send FIN in this state.
 236  *      sS2 -> sIV
 237  *      sSR -> sFW      Close started.
 238  *      sES -> sFW
 239  *      sFW -> sLA      FIN seen in both directions.
 240  *      sCW -> sLA
 241  *      sLA -> sLA      Retransmitted FIN.
 242  *      sTW -> sTW
 243  *      sCL -> sCL
 244  */
 245 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 246 /*ack*/    { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
 247 /*
 248  *      sSS -> sIG      Might be a half-open connection.
 249  *      sS2 -> sIG
 250  *      sSR -> sSR      Might answer late resent SYN.
 251  *      sES -> sES      :-)
 252  *      sFW -> sCW      Normal close request answered by ACK.
 253  *      sCW -> sCW
 254  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 255  *      sTW -> sTW      Retransmitted last ACK.
 256  *      sCL -> sCL
 257  */
 258 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 259 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 260 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 261         }
 262 };
 263
 264 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 265 /* Print out the private part of the conntrack. */
 266 static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 267 {
 268         if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
 269                 return;
 270
 271         seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
 272 }
 273 #endif
 274
 275 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
 276 {
 277         if (tcph->rst) return TCP_RST_SET;
 278         else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
 279         else if (tcph->fin) return TCP_FIN_SET;
 280         else if (tcph->ack) return TCP_ACK_SET;
 281         else return TCP_NONE_SET;
 282 }
 283
 284 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
 285    in IP Filter' by Guido van Rooij.
 286
 287    http://www.sane.nl/events/sane2000/papers.html
 288    http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
 289
 290    The boundaries and the conditions are changed according to RFC793:
 291    the packet must intersect the window (i.e. segments may be
 292    after the right or before the left edge) and thus receivers may ACK
 293    segments after the right edge of the window.
 294
 295         td_maxend = max(sack + max(win,1)) seen in reply packets
 296         td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
 297         td_maxwin += seq + len - sender.td_maxend
 298                         if seq + len > sender.td_maxend
 299         td_end    = max(seq + len) seen in sent packets
 300
 301    I.   Upper bound for valid data:     seq <= sender.td_maxend
 302    II.  Lower bound for valid data:     seq + len >= sender.td_end - receiver.td_maxwin
 303    III. Upper bound for valid (s)ack:   sack <= receiver.td_end
 304    IV.  Lower bound for valid (s)ack:   sack >= receiver.td_end - MAXACKWINDOW
 305
 306    where sack is the highest right edge of sack block found in the packet
 307    or ack in the case of packet without SACK option.
 308
 309    The upper bound limit for a valid (s)ack is not ignored -
 310    we doesn't have to deal with fragments.
 311 */
 312
 313 static inline __u32 segment_seq_plus_len(__u32 seq,
 314                                          size_t len,
 315                                          unsigned int dataoff,
 316                                          const struct tcphdr *tcph)
 317 {
 318         /* XXX Should I use payload length field in IP/IPv6 header ?
 319          * - YK */
 320         return (seq + len - dataoff - tcph->doff*4
 321                 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
 322 }
 323
 324 /* Fixme: what about big packets? */
 325 #define MAXACKWINCONST                  66000
 326 #define MAXACKWINDOW(sender)                                            \
 327         ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin     \
 328                                               : MAXACKWINCONST)
 329
 330 /*
 331  * Simplified tcp_parse_options routine from tcp_input.c
 332  */
 333 static void tcp_options(const struct sk_buff *skb,
 334                         unsigned int dataoff,
 335                         const struct tcphdr *tcph,
 336                         struct ip_ct_tcp_state *state)
 337 {
 338         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 339         const unsigned char *ptr;
 340         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 341
 342         if (!length)
 343                 return;
 344
 345         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 346                                  length, buff);
 347         if (!ptr)
 348                 return;
 349
 350         state->td_scale = 0;
 351         state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
 352
 353         while (length > 0) {
 354                 int opcode=*ptr++;
 355                 int opsize;
 356
 357                 switch (opcode) {
 358                 case TCPOPT_EOL:
 359                         return;
 360                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 361                         length--;
 362                         continue;
 363                 default:
 364                         if (length < 2)
 365                                 return;
 366                         opsize=*ptr++;
 367                         if (opsize < 2) /* "silly options" */
 368                                 return;
 369                         if (opsize > length)
 370                                 return; /* don't parse partial options */
 371
 372                         if (opcode == TCPOPT_SACK_PERM
 373                             && opsize == TCPOLEN_SACK_PERM)
 374                                 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
 375                         else if (opcode == TCPOPT_WINDOW
 376                                  && opsize == TCPOLEN_WINDOW) {
 377                                 state->td_scale = *(u_int8_t *)ptr;
 378
 379                                 if (state->td_scale > TCP_MAX_WSCALE)
 380                                         state->td_scale = TCP_MAX_WSCALE;
 381
 382                                 state->flags |=
 383                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 384                         }
 385                         ptr += opsize - 2;
 386                         length -= opsize;
 387                 }
 388         }
 389 }
 390
 391 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
 392                      const struct tcphdr *tcph, __u32 *sack)
 393 {
 394         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 395         const unsigned char *ptr;
 396         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 397         __u32 tmp;
 398
 399         if (!length)
 400                 return;
 401
 402         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 403                                  length, buff);
 404         if (!ptr)
 405                 return;
 406
 407         /* Fast path for timestamp-only option */
 408         if (length == TCPOLEN_TSTAMP_ALIGNED
 409             && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
 410                                        | (TCPOPT_NOP << 16)
 411                                        | (TCPOPT_TIMESTAMP << 8)
 412                                        | TCPOLEN_TIMESTAMP))
 413                 return;
 414
 415         while (length > 0) {
 416                 int opcode = *ptr++;
 417                 int opsize, i;
 418
 419                 switch (opcode) {
 420                 case TCPOPT_EOL:
 421                         return;
 422                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 423                         length--;
 424                         continue;
 425                 default:
 426                         if (length < 2)
 427                                 return;
 428                         opsize = *ptr++;
 429                         if (opsize < 2) /* "silly options" */
 430                                 return;
 431                         if (opsize > length)
 432                                 return; /* don't parse partial options */
 433
 434                         if (opcode == TCPOPT_SACK
 435                             && opsize >= (TCPOLEN_SACK_BASE
 436                                           + TCPOLEN_SACK_PERBLOCK)
 437                             && !((opsize - TCPOLEN_SACK_BASE)
 438                                  % TCPOLEN_SACK_PERBLOCK)) {
 439                                 for (i = 0;
 440                                      i < (opsize - TCPOLEN_SACK_BASE);
 441                                      i += TCPOLEN_SACK_PERBLOCK) {
 442                                         tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
 443
 444                                         if (after(tmp, *sack))
 445                                                 *sack = tmp;
 446                                 }
 447                                 return;
 448                         }
 449                         ptr += opsize - 2;
 450                         length -= opsize;
 451                 }
 452         }
 453 }
 454
 455 static void tcp_init_sender(struct ip_ct_tcp_state *sender,
 456                             struct ip_ct_tcp_state *receiver,
 457                             const struct sk_buff *skb,
 458                             unsigned int dataoff,
 459                             const struct tcphdr *tcph,
 460                             u32 end, u32 win)
 461 {
 462         /* SYN-ACK in reply to a SYN
 463          * or SYN from reply direction in simultaneous open.
 464          */
 465         sender->td_end =
 466         sender->td_maxend = end;
 467         sender->td_maxwin = (win == 0 ? 1 : win);
 468
 469         tcp_options(skb, dataoff, tcph, sender);
 470         /* RFC 1323:
 471          * Both sides must send the Window Scale option
 472          * to enable window scaling in either direction.
 473          */
 474         if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
 475               receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) {
 476                 sender->td_scale = 0;
 477                 receiver->td_scale = 0;
 478         }
 479 }
 480
 481 __printf(6, 7)
 482 static enum nf_ct_tcp_action nf_tcp_log_invalid(const struct sk_buff *skb,
 483                                                 const struct nf_conn *ct,
 484                                                 const struct nf_hook_state *state,
 485                                                 const struct ip_ct_tcp_state *sender,
 486                                                 enum nf_ct_tcp_action ret,
 487                                                 const char *fmt, ...)
 488 {
 489         const struct nf_tcp_net *tn = nf_tcp_pernet(nf_ct_net(ct));
 490         struct va_format vaf;
 491         va_list args;
 492         bool be_liberal;
 493
 494         be_liberal = sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || tn->tcp_be_liberal;
 495         if (be_liberal)
 496                 return NFCT_TCP_ACCEPT;
 497
 498         va_start(args, fmt);
 499         vaf.fmt = fmt;
 500         vaf.va = &args;
 501         nf_ct_l4proto_log_invalid(skb, ct, state, "%pV", &vaf);
 502         va_end(args);
 503
 504         return ret;
 505 }
 506
 507 static enum nf_ct_tcp_action
 508 tcp_in_window(struct nf_conn *ct, enum ip_conntrack_dir dir,
 509               unsigned int index, const struct sk_buff *skb,
 510               unsigned int dataoff, const struct tcphdr *tcph,
 511               const struct nf_hook_state *hook_state)
 512 {
 513         struct ip_ct_tcp *state = &ct->proto.tcp;
 514         struct ip_ct_tcp_state *sender = &state->seen[dir];
 515         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 516         __u32 seq, ack, sack, end, win, swin;
 517         bool in_recv_win, seq_ok;
 518         s32 receiver_offset;
 519         u16 win_raw;
 520
 521         /*
 522          * Get the required data from the packet.
 523          */
 524         seq = ntohl(tcph->seq);
 525         ack = sack = ntohl(tcph->ack_seq);
 526         win_raw = ntohs(tcph->window);
 527         win = win_raw;
 528         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
 529
 530         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
 531                 tcp_sack(skb, dataoff, tcph, &sack);
 532
 533         /* Take into account NAT sequence number mangling */
 534         receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
 535         ack -= receiver_offset;
 536         sack -= receiver_offset;
 537
 538         if (sender->td_maxwin == 0) {
 539                 /*
 540                  * Initialize sender data.
 541                  */
 542                 if (tcph->syn) {
 543                         tcp_init_sender(sender, receiver,
 544                                         skb, dataoff, tcph,
 545                                         end, win);
 546                         if (!tcph->ack)
 547                                 /* Simultaneous open */
 548                                 return NFCT_TCP_ACCEPT;
 549                 } else {
 550                         /*
 551                          * We are in the middle of a connection,
 552                          * its history is lost for us.
 553                          * Let's try to use the data from the packet.
 554                          */
 555                         sender->td_end = end;
 556                         swin = win << sender->td_scale;
 557                         sender->td_maxwin = (swin == 0 ? 1 : swin);
 558                         sender->td_maxend = end + sender->td_maxwin;
 559                         if (receiver->td_maxwin == 0) {
 560                                 /* We haven't seen traffic in the other
 561                                  * direction yet but we have to tweak window
 562                                  * tracking to pass III and IV until that
 563                                  * happens.
 564                                  */
 565                                 receiver->td_end = receiver->td_maxend = sack;
 566                         } else if (sack == receiver->td_end + 1) {
 567                                 /* Likely a reply to a keepalive.
 568                                  * Needed for III.
 569                                  */
 570                                 receiver->td_end++;
 571                         }
 572
 573                 }
 574         } else if (tcph->syn &&
 575                    after(end, sender->td_end) &&
 576                    (state->state == TCP_CONNTRACK_SYN_SENT ||
 577                     state->state == TCP_CONNTRACK_SYN_RECV)) {
 578                 /*
 579                  * RFC 793: "if a TCP is reinitialized ... then it need
 580                  * not wait at all; it must only be sure to use sequence
 581                  * numbers larger than those recently used."
 582                  *
 583                  * Re-init state for this direction, just like for the first
 584                  * syn(-ack) reply, it might differ in seq, ack or tcp options.
 585                  */
 586                 tcp_init_sender(sender, receiver,
 587                                 skb, dataoff, tcph,
 588                                 end, win);
 589
 590                 if (dir == IP_CT_DIR_REPLY && !tcph->ack)
 591                         return NFCT_TCP_ACCEPT;
 592         }
 593
 594         if (!(tcph->ack)) {
 595                 /*
 596                  * If there is no ACK, just pretend it was set and OK.
 597                  */
 598                 ack = sack = receiver->td_end;
 599         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
 600                     (TCP_FLAG_ACK|TCP_FLAG_RST))
 601                    && (ack == 0)) {
 602                 /*
 603                  * Broken TCP stacks, that set ACK in RST packets as well
 604                  * with zero ack value.
 605                  */
 606                 ack = sack = receiver->td_end;
 607         }
 608
 609         if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
 610                 /*
 611                  * RST sent answering SYN.
 612                  */
 613                 seq = end = sender->td_end;
 614
 615         seq_ok = before(seq, sender->td_maxend + 1);
 616         if (!seq_ok) {
 617                 u32 overshot = end - sender->td_maxend + 1;
 618                 bool ack_ok;
 619
 620                 ack_ok = after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1);
 621                 in_recv_win = receiver->td_maxwin &&
 622                               after(end, sender->td_end - receiver->td_maxwin - 1);
 623
 624                 if (in_recv_win &&
 625                     ack_ok &&
 626                     overshot <= receiver->td_maxwin &&
 627                     before(sack, receiver->td_end + 1)) {
 628                         /* Work around TCPs that send more bytes than allowed by
 629                          * the receive window.
 630                          *
 631                          * If the (marked as invalid) packet is allowed to pass by
 632                          * the ruleset and the peer acks this data, then its possible
 633                          * all future packets will trigger 'ACK is over upper bound' check.
 634                          *
 635                          * Thus if only the sequence check fails then do update td_end so
 636                          * possible ACK for this data can update internal state.
 637                          */
 638                         sender->td_end = end;
 639                         sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 640
 641                         return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 642                                                   "%u bytes more than expected", overshot);
 643                 }
 644
 645                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
 646                                           "SEQ is over upper bound %u (over the window of the receiver)",
 647                                           sender->td_maxend + 1);
 648         }
 649
 650         if (!before(sack, receiver->td_end + 1))
 651                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
 652                                           "ACK is over upper bound %u (ACKed data not seen yet)",
 653                                           receiver->td_end + 1);
 654
 655         /* Is the ending sequence in the receive window (if available)? */
 656         in_recv_win = !receiver->td_maxwin ||
 657                       after(end, sender->td_end - receiver->td_maxwin - 1);
 658         if (!in_recv_win)
 659                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 660                                           "SEQ is under lower bound %u (already ACKed data retransmitted)",
 661                                           sender->td_end - receiver->td_maxwin - 1);
 662         if (!after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1))
 663                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 664                                           "ignored ACK under lower bound %u (possible overly delayed)",
 665                                           receiver->td_end - MAXACKWINDOW(sender) - 1);
 666
 667         /* Take into account window scaling (RFC 1323). */
 668         if (!tcph->syn)
 669                 win <<= sender->td_scale;
 670
 671         /* Update sender data. */
 672         swin = win + (sack - ack);
 673         if (sender->td_maxwin < swin)
 674                 sender->td_maxwin = swin;
 675         if (after(end, sender->td_end)) {
 676                 sender->td_end = end;
 677                 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 678         }
 679         if (tcph->ack) {
 680                 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
 681                         sender->td_maxack = ack;
 682                         sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
 683                 } else if (after(ack, sender->td_maxack)) {
 684                         sender->td_maxack = ack;
 685                 }
 686         }
 687
 688         /* Update receiver data. */
 689         if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
 690                 receiver->td_maxwin += end - sender->td_maxend;
 691         if (after(sack + win, receiver->td_maxend - 1)) {
 692                 receiver->td_maxend = sack + win;
 693                 if (win == 0)
 694                         receiver->td_maxend++;
 695         }
 696         if (ack == receiver->td_end)
 697                 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 698
 699         /* Check retransmissions. */
 700         if (index == TCP_ACK_SET) {
 701                 if (state->last_dir == dir &&
 702                     state->last_seq == seq &&
 703                     state->last_ack == ack &&
 704                     state->last_end == end &&
 705                     state->last_win == win_raw) {
 706                         state->retrans++;
 707                 } else {
 708                         state->last_dir = dir;
 709                         state->last_seq = seq;
 710                         state->last_ack = ack;
 711                         state->last_end = end;
 712                         state->last_win = win_raw;
 713                         state->retrans = 0;
 714                 }
 715         }
 716
 717         return NFCT_TCP_ACCEPT;
 718 }
 719
 720 static void __cold nf_tcp_handle_invalid(struct nf_conn *ct,
 721                                          enum ip_conntrack_dir dir,
 722                                          int index,
 723                                          const struct sk_buff *skb,
 724                                          const struct nf_hook_state *hook_state)
 725 {
 726         const unsigned int *timeouts;
 727         const struct nf_tcp_net *tn;
 728         unsigned int timeout;
 729         u32 expires;
 730
 731         if (!test_bit(IPS_ASSURED_BIT, &ct->status) ||
 732             test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
 733                 return;
 734
 735         /* We don't want to have connections hanging around in ESTABLISHED
 736          * state for long time 'just because' conntrack deemed a FIN/RST
 737          * out-of-window.
 738          *
 739          * Shrink the timeout just like when there is unacked data.
 740          * This speeds up eviction of 'dead' connections where the
 741          * connection and conntracks internal state are out of sync.
 742          */
 743         switch (index) {
 744         case TCP_RST_SET:
 745         case TCP_FIN_SET:
 746                 break;
 747         default:
 748                 return;
 749         }
 750
 751         if (ct->proto.tcp.last_dir != dir &&
 752             (ct->proto.tcp.last_index == TCP_FIN_SET ||
 753              ct->proto.tcp.last_index == TCP_RST_SET)) {
 754                 expires = nf_ct_expires(ct);
 755                 if (expires < 120 * HZ)
 756                         return;
 757
 758                 tn = nf_tcp_pernet(nf_ct_net(ct));
 759                 timeouts = nf_ct_timeout_lookup(ct);
 760                 if (!timeouts)
 761                         timeouts = tn->timeouts;
 762
 763                 timeout = READ_ONCE(timeouts[TCP_CONNTRACK_UNACK]);
 764                 if (expires > timeout) {
 765                         nf_ct_l4proto_log_invalid(skb, ct, hook_state,
 766                                           "packet (index %d, dir %d) response for index %d lower timeout to %u",
 767                                           index, dir, ct->proto.tcp.last_index, timeout);
 768
 769                         WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp);
 770                 }
 771         } else {
 772                 ct->proto.tcp.last_index = index;
 773                 ct->proto.tcp.last_dir = dir;
 774         }
 775 }
 776
 777 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
 778 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
 779                                  TCPHDR_URG) + 1] =
 780 {
 781         [TCPHDR_SYN]                            = 1,
 782         [TCPHDR_SYN|TCPHDR_URG]                 = 1,
 783         [TCPHDR_SYN|TCPHDR_ACK]                 = 1,
 784         [TCPHDR_RST]                            = 1,
 785         [TCPHDR_RST|TCPHDR_ACK]                 = 1,
 786         [TCPHDR_FIN|TCPHDR_ACK]                 = 1,
 787         [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG]      = 1,
 788         [TCPHDR_ACK]                            = 1,
 789         [TCPHDR_ACK|TCPHDR_URG]                 = 1,
 790 };
 791
 792 static void tcp_error_log(const struct sk_buff *skb,
 793                           const struct nf_hook_state *state,
 794                           const char *msg)
 795 {
 796         nf_l4proto_log_invalid(skb, state, IPPROTO_TCP, "%s", msg);
 797 }
 798
 799 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
 800 static bool tcp_error(const struct tcphdr *th,
 801                       struct sk_buff *skb,
 802                       unsigned int dataoff,
 803                       const struct nf_hook_state *state)
 804 {
 805         unsigned int tcplen = skb->len - dataoff;
 806         u8 tcpflags;
 807
 808         /* Not whole TCP header or malformed packet */
 809         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
 810                 tcp_error_log(skb, state, "truncated packet");
 811                 return true;
 812         }
 813
 814         /* Checksum invalid? Ignore.
 815          * We skip checking packets on the outgoing path
 816          * because the checksum is assumed to be correct.
 817          */
 818         /* FIXME: Source route IP option packets --RR */
 819         if (state->net->ct.sysctl_checksum &&
 820             state->hook == NF_INET_PRE_ROUTING &&
 821             nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
 822                 tcp_error_log(skb, state, "bad checksum");
 823                 return true;
 824         }
 825
 826         /* Check TCP flags. */
 827         tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
 828         if (!tcp_valid_flags[tcpflags]) {
 829                 tcp_error_log(skb, state, "invalid tcp flag combination");
 830                 return true;
 831         }
 832
 833         return false;
 834 }
 835
 836 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
 837                              unsigned int dataoff,
 838                              const struct tcphdr *th)
 839 {
 840         enum tcp_conntrack new_state;
 841         struct net *net = nf_ct_net(ct);
 842         const struct nf_tcp_net *tn = nf_tcp_pernet(net);
 843
 844         /* Don't need lock here: this conntrack not in circulation yet */
 845         new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
 846
 847         /* Invalid: delete conntrack */
 848         if (new_state >= TCP_CONNTRACK_MAX) {
 849                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
 850                 return false;
 851         }
 852
 853         if (new_state == TCP_CONNTRACK_SYN_SENT) {
 854                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 855                 /* SYN packet */
 856                 ct->proto.tcp.seen[0].td_end =
 857                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 858                                              dataoff, th);
 859                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 860                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 861                         ct->proto.tcp.seen[0].td_maxwin = 1;
 862                 ct->proto.tcp.seen[0].td_maxend =
 863                         ct->proto.tcp.seen[0].td_end;
 864
 865                 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
 866         } else if (tn->tcp_loose == 0) {
 867                 /* Don't try to pick up connections. */
 868                 return false;
 869         } else {
 870                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 871                 /*
 872                  * We are in the middle of a connection,
 873                  * its history is lost for us.
 874                  * Let's try to use the data from the packet.
 875                  */
 876                 ct->proto.tcp.seen[0].td_end =
 877                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 878                                              dataoff, th);
 879                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 880                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 881                         ct->proto.tcp.seen[0].td_maxwin = 1;
 882                 ct->proto.tcp.seen[0].td_maxend =
 883                         ct->proto.tcp.seen[0].td_end +
 884                         ct->proto.tcp.seen[0].td_maxwin;
 885
 886                 /* We assume SACK and liberal window checking to handle
 887                  * window scaling */
 888                 ct->proto.tcp.seen[0].flags =
 889                 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
 890                                               IP_CT_TCP_FLAG_BE_LIBERAL;
 891         }
 892
 893         /* tcp_packet will set them */
 894         ct->proto.tcp.last_index = TCP_NONE_SET;
 895         return true;
 896 }
 897
 898 static bool tcp_can_early_drop(const struct nf_conn *ct)
 899 {
 900         switch (ct->proto.tcp.state) {
 901         case TCP_CONNTRACK_FIN_WAIT:
 902         case TCP_CONNTRACK_LAST_ACK:
 903         case TCP_CONNTRACK_TIME_WAIT:
 904         case TCP_CONNTRACK_CLOSE:
 905         case TCP_CONNTRACK_CLOSE_WAIT:
 906                 return true;
 907         default:
 908                 break;
 909         }
 910
 911         return false;
 912 }
 913
 914 static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state)
 915 {
 916         state->td_end           = 0;
 917         state->td_maxend        = 0;
 918         state->td_maxwin        = 0;
 919         state->td_maxack        = 0;
 920         state->td_scale         = 0;
 921         state->flags            &= IP_CT_TCP_FLAG_BE_LIBERAL;
 922 }
 923
 924 /* Returns verdict for packet, or -1 for invalid. */
 925 int nf_conntrack_tcp_packet(struct nf_conn *ct,
 926                             struct sk_buff *skb,
 927                             unsigned int dataoff,
 928                             enum ip_conntrack_info ctinfo,
 929                             const struct nf_hook_state *state)
 930 {
 931         struct net *net = nf_ct_net(ct);
 932         struct nf_tcp_net *tn = nf_tcp_pernet(net);
 933         struct nf_conntrack_tuple *tuple;
 934         enum tcp_conntrack new_state, old_state;
 935         unsigned int index, *timeouts;
 936         enum nf_ct_tcp_action res;
 937         enum ip_conntrack_dir dir;
 938         const struct tcphdr *th;
 939         struct tcphdr _tcph;
 940         unsigned long timeout;
 941
 942         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 943         if (th == NULL)
 944                 return -NF_ACCEPT;
 945
 946         if (tcp_error(th, skb, dataoff, state))
 947                 return -NF_ACCEPT;
 948
 949         if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
 950                 return -NF_ACCEPT;
 951
 952         spin_lock_bh(&ct->lock);
 953         old_state = ct->proto.tcp.state;
 954         dir = CTINFO2DIR(ctinfo);
 955         index = get_conntrack_index(th);
 956         new_state = tcp_conntracks[dir][index][old_state];
 957         tuple = &ct->tuplehash[dir].tuple;
 958
 959         switch (new_state) {
 960         case TCP_CONNTRACK_SYN_SENT:
 961                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 962                         break;
 963                 /* RFC 1122: "When a connection is closed actively,
 964                  * it MUST linger in TIME-WAIT state for a time 2xMSL
 965                  * (Maximum Segment Lifetime). However, it MAY accept
 966                  * a new SYN from the remote TCP to reopen the connection
 967                  * directly from TIME-WAIT state, if..."
 968                  * We ignore the conditions because we are in the
 969                  * TIME-WAIT state anyway.
 970                  *
 971                  * Handle aborted connections: we and the server
 972                  * think there is an existing connection but the client
 973                  * aborts it and starts a new one.
 974                  */
 975                 if (((ct->proto.tcp.seen[dir].flags
 976                       | ct->proto.tcp.seen[!dir].flags)
 977                      & IP_CT_TCP_FLAG_CLOSE_INIT)
 978                     || (ct->proto.tcp.last_dir == dir
 979                         && ct->proto.tcp.last_index == TCP_RST_SET)) {
 980                         /* Attempt to reopen a closed/aborted connection.
 981                          * Delete this connection and look up again. */
 982                         spin_unlock_bh(&ct->lock);
 983
 984                         /* Only repeat if we can actually remove the timer.
 985                          * Destruction may already be in progress in process
 986                          * context and we must give it a chance to terminate.
 987                          */
 988                         if (nf_ct_kill(ct))
 989                                 return -NF_REPEAT;
 990                         return NF_DROP;
 991                 }
 992                 fallthrough;
 993         case TCP_CONNTRACK_IGNORE:
 994                 /* Ignored packets:
 995                  *
 996                  * Our connection entry may be out of sync, so ignore
 997                  * packets which may signal the real connection between
 998                  * the client and the server.
 999                  *
1000                  * a) SYN in ORIGINAL
1001                  * b) SYN/ACK in REPLY
1002                  * c) ACK in reply direction after initial SYN in original.
1003                  *
1004                  * If the ignored packet is invalid, the receiver will send
1005                  * a RST we'll catch below.
1006                  */
1007                 if (index == TCP_SYNACK_SET
1008                     && ct->proto.tcp.last_index == TCP_SYN_SET
1009                     && ct->proto.tcp.last_dir != dir
1010                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1011                         /* b) This SYN/ACK acknowledges a SYN that we earlier
1012                          * ignored as invalid. This means that the client and
1013                          * the server are both in sync, while the firewall is
1014                          * not. We get in sync from the previously annotated
1015                          * values.
1016                          */
1017                         old_state = TCP_CONNTRACK_SYN_SENT;
1018                         new_state = TCP_CONNTRACK_SYN_RECV;
1019                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
1020                                 ct->proto.tcp.last_end;
1021                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
1022                                 ct->proto.tcp.last_end;
1023                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
1024                                 ct->proto.tcp.last_win == 0 ?
1025                                         1 : ct->proto.tcp.last_win;
1026                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
1027                                 ct->proto.tcp.last_wscale;
1028                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1029                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
1030                                 ct->proto.tcp.last_flags;
1031                         nf_ct_tcp_state_reset(&ct->proto.tcp.seen[dir]);
1032                         break;
1033                 }
1034                 ct->proto.tcp.last_index = index;
1035                 ct->proto.tcp.last_dir = dir;
1036                 ct->proto.tcp.last_seq = ntohl(th->seq);
1037                 ct->proto.tcp.last_end =
1038                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
1039                 ct->proto.tcp.last_win = ntohs(th->window);
1040
1041                 /* a) This is a SYN in ORIGINAL. The client and the server
1042                  * may be in sync but we are not. In that case, we annotate
1043                  * the TCP options and let the packet go through. If it is a
1044                  * valid SYN packet, the server will reply with a SYN/ACK, and
1045                  * then we'll get in sync. Otherwise, the server potentially
1046                  * responds with a challenge ACK if implementing RFC5961.
1047                  */
1048                 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
1049                         struct ip_ct_tcp_state seen = {};
1050
1051                         ct->proto.tcp.last_flags =
1052                         ct->proto.tcp.last_wscale = 0;
1053                         tcp_options(skb, dataoff, th, &seen);
1054                         if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1055                                 ct->proto.tcp.last_flags |=
1056                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
1057                                 ct->proto.tcp.last_wscale = seen.td_scale;
1058                         }
1059                         if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
1060                                 ct->proto.tcp.last_flags |=
1061                                         IP_CT_TCP_FLAG_SACK_PERM;
1062                         }
1063                         /* Mark the potential for RFC5961 challenge ACK,
1064                          * this pose a special problem for LAST_ACK state
1065                          * as ACK is intrepretated as ACKing last FIN.
1066                          */
1067                         if (old_state == TCP_CONNTRACK_LAST_ACK)
1068                                 ct->proto.tcp.last_flags |=
1069                                         IP_CT_EXP_CHALLENGE_ACK;
1070                 }
1071                 spin_unlock_bh(&ct->lock);
1072                 nf_ct_l4proto_log_invalid(skb, ct, state,
1073                                           "packet (index %d) in dir %d ignored, state %s",
1074                                           index, dir,
1075                                           tcp_conntrack_names[old_state]);
1076                 return NF_ACCEPT;
1077         case TCP_CONNTRACK_MAX:
1078                 /* Special case for SYN proxy: when the SYN to the server or
1079                  * the SYN/ACK from the server is lost, the client may transmit
1080                  * a keep-alive packet while in SYN_SENT state. This needs to
1081                  * be associated with the original conntrack entry in order to
1082                  * generate a new SYN with the correct sequence number.
1083                  */
1084                 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
1085                     index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
1086                     ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1087                     ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1088                         pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1089                         spin_unlock_bh(&ct->lock);
1090                         return NF_ACCEPT;
1091                 }
1092
1093                 /* Invalid packet */
1094                 spin_unlock_bh(&ct->lock);
1095                 nf_ct_l4proto_log_invalid(skb, ct, state,
1096                                           "packet (index %d) in dir %d invalid, state %s",
1097                                           index, dir,
1098                                           tcp_conntrack_names[old_state]);
1099                 return -NF_ACCEPT;
1100         case TCP_CONNTRACK_TIME_WAIT:
1101                 /* RFC5961 compliance cause stack to send "challenge-ACK"
1102                  * e.g. in response to spurious SYNs.  Conntrack MUST
1103                  * not believe this ACK is acking last FIN.
1104                  */
1105                 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1106                     index == TCP_ACK_SET &&
1107                     ct->proto.tcp.last_dir != dir &&
1108                     ct->proto.tcp.last_index == TCP_SYN_SET &&
1109                     (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1110                         /* Detected RFC5961 challenge ACK */
1111                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1112                         spin_unlock_bh(&ct->lock);
1113                         nf_ct_l4proto_log_invalid(skb, ct, state, "challenge-ack ignored");
1114                         return NF_ACCEPT; /* Don't change state */
1115                 }
1116                 break;
1117         case TCP_CONNTRACK_SYN_SENT2:
1118                 /* tcp_conntracks table is not smart enough to handle
1119                  * simultaneous open.
1120                  */
1121                 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1122                 break;
1123         case TCP_CONNTRACK_SYN_RECV:
1124                 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1125                     ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1126                         new_state = TCP_CONNTRACK_ESTABLISHED;
1127                 break;
1128         case TCP_CONNTRACK_CLOSE:
1129                 if (index != TCP_RST_SET)
1130                         break;
1131
1132                 /* If we are closing, tuple might have been re-used already.
1133                  * last_index, last_ack, and all other ct fields used for
1134                  * sequence/window validation are outdated in that case.
1135                  *
1136                  * As the conntrack can already be expired by GC under pressure,
1137                  * just skip validation checks.
1138                  */
1139                 if (tcp_can_early_drop(ct))
1140                         goto in_window;
1141
1142                 /* td_maxack might be outdated if we let a SYN through earlier */
1143                 if ((ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) &&
1144                     ct->proto.tcp.last_index != TCP_SYN_SET) {
1145                         u32 seq = ntohl(th->seq);
1146
1147                         /* If we are not in established state and SEQ=0 this is most
1148                          * likely an answer to a SYN we let go through above (last_index
1149                          * can be updated due to out-of-order ACKs).
1150                          */
1151                         if (seq == 0 && !nf_conntrack_tcp_established(ct))
1152                                 break;
1153
1154                         if (before(seq, ct->proto.tcp.seen[!dir].td_maxack) &&
1155                             !tn->tcp_ignore_invalid_rst) {
1156                                 /* Invalid RST  */
1157                                 spin_unlock_bh(&ct->lock);
1158                                 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid rst");
1159                                 return -NF_ACCEPT;
1160                         }
1161
1162                         if (!nf_conntrack_tcp_established(ct) ||
1163                             seq == ct->proto.tcp.seen[!dir].td_maxack)
1164                                 break;
1165
1166                         /* Check if rst is part of train, such as
1167                          *   foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1168                          *   foo:80 > bar:4379: R, 235946602:235946602(0)  ack 42
1169                          */
1170                         if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1171                             ct->proto.tcp.last_dir == dir &&
1172                             seq == ct->proto.tcp.last_end)
1173                                 break;
1174
1175                         /* ... RST sequence number doesn't match exactly, keep
1176                          * established state to allow a possible challenge ACK.
1177                          */
1178                         new_state = old_state;
1179                 }
1180                 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1181                          && ct->proto.tcp.last_index == TCP_SYN_SET)
1182                         || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1183                             && ct->proto.tcp.last_index == TCP_ACK_SET))
1184                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1185                         /* RST sent to invalid SYN or ACK we had let through
1186                          * at a) and c) above:
1187                          *
1188                          * a) SYN was in window then
1189                          * c) we hold a half-open connection.
1190                          *
1191                          * Delete our connection entry.
1192                          * We skip window checking, because packet might ACK
1193                          * segments we ignored. */
1194                         goto in_window;
1195                 }
1196                 break;
1197         default:
1198                 /* Keep compilers happy. */
1199                 break;
1200         }
1201
1202         res = tcp_in_window(ct, dir, index,
1203                             skb, dataoff, th, state);
1204         switch (res) {
1205         case NFCT_TCP_IGNORE:
1206                 spin_unlock_bh(&ct->lock);
1207                 return NF_ACCEPT;
1208         case NFCT_TCP_INVALID:
1209                 nf_tcp_handle_invalid(ct, dir, index, skb, state);
1210                 spin_unlock_bh(&ct->lock);
1211                 return -NF_ACCEPT;
1212         case NFCT_TCP_ACCEPT:
1213                 break;
1214         }
1215      in_window:
1216         /* From now on we have got in-window packets */
1217         ct->proto.tcp.last_index = index;
1218         ct->proto.tcp.last_dir = dir;
1219
1220         pr_debug("tcp_conntracks: ");
1221         nf_ct_dump_tuple(tuple);
1222         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1223                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1224                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1225                  old_state, new_state);
1226
1227         ct->proto.tcp.state = new_state;
1228         if (old_state != new_state
1229             && new_state == TCP_CONNTRACK_FIN_WAIT)
1230                 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1231
1232         timeouts = nf_ct_timeout_lookup(ct);
1233         if (!timeouts)
1234                 timeouts = tn->timeouts;
1235
1236         if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1237             timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1238                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1239         else if (unlikely(index == TCP_RST_SET))
1240                 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1241         else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1242                  IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1243                  timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1244                 timeout = timeouts[TCP_CONNTRACK_UNACK];
1245         else if (ct->proto.tcp.last_win == 0 &&
1246                  timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1247                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1248         else
1249                 timeout = timeouts[new_state];
1250         spin_unlock_bh(&ct->lock);
1251
1252         if (new_state != old_state)
1253                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1254
1255         if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1256                 /* If only reply is a RST, we can consider ourselves not to
1257                    have an established connection: this is a fairly common
1258                    problem case, so we can delete the conntrack
1259                    immediately.  --RR */
1260                 if (th->rst) {
1261                         nf_ct_kill_acct(ct, ctinfo, skb);
1262                         return NF_ACCEPT;
1263                 }
1264
1265                 if (index == TCP_SYN_SET && old_state == TCP_CONNTRACK_SYN_SENT) {
1266                         /* do not renew timeout on SYN retransmit.
1267                          *
1268                          * Else port reuse by client or NAT middlebox can keep
1269                          * entry alive indefinitely (including nat info).
1270                          */
1271                         return NF_ACCEPT;
1272                 }
1273
1274                 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1275                  * pickup with loose=1. Avoid large ESTABLISHED timeout.
1276                  */
1277                 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1278                     timeout > timeouts[TCP_CONNTRACK_UNACK])
1279                         timeout = timeouts[TCP_CONNTRACK_UNACK];
1280         } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1281                    && (old_state == TCP_CONNTRACK_SYN_RECV
1282                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1283                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1284                 /* Set ASSURED if we see valid ack in ESTABLISHED
1285                    after SYN_RECV or a valid answer for a picked up
1286                    connection. */
1287                 set_bit(IPS_ASSURED_BIT, &ct->status);
1288                 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1289         }
1290         nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1291
1292         return NF_ACCEPT;
1293 }
1294
1295 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1296
1297 #include <linux/netfilter/nfnetlink.h>
1298 #include <linux/netfilter/nfnetlink_conntrack.h>
1299
1300 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1301                          struct nf_conn *ct, bool destroy)
1302 {
1303         struct nlattr *nest_parms;
1304         struct nf_ct_tcp_flags tmp = {};
1305
1306         spin_lock_bh(&ct->lock);
1307         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1308         if (!nest_parms)
1309                 goto nla_put_failure;
1310
1311         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1312                 goto nla_put_failure;
1313
1314         if (destroy)
1315                 goto skip_state;
1316
1317         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1318                        ct->proto.tcp.seen[0].td_scale) ||
1319             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1320                        ct->proto.tcp.seen[1].td_scale))
1321                 goto nla_put_failure;
1322
1323         tmp.flags = ct->proto.tcp.seen[0].flags;
1324         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1325                     sizeof(struct nf_ct_tcp_flags), &tmp))
1326                 goto nla_put_failure;
1327
1328         tmp.flags = ct->proto.tcp.seen[1].flags;
1329         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1330                     sizeof(struct nf_ct_tcp_flags), &tmp))
1331                 goto nla_put_failure;
1332 skip_state:
1333         spin_unlock_bh(&ct->lock);
1334         nla_nest_end(skb, nest_parms);
1335
1336         return 0;
1337
1338 nla_put_failure:
1339         spin_unlock_bh(&ct->lock);
1340         return -1;
1341 }
1342
1343 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1344         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1345         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1346         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1347         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1348         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len = sizeof(struct nf_ct_tcp_flags) },
1349 };
1350
1351 #define TCP_NLATTR_SIZE ( \
1352         NLA_ALIGN(NLA_HDRLEN + 1) + \
1353         NLA_ALIGN(NLA_HDRLEN + 1) + \
1354         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1355         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1356
1357 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1358 {
1359         struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1360         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1361         int err;
1362
1363         /* updates could not contain anything about the private
1364          * protocol info, in that case skip the parsing */
1365         if (!pattr)
1366                 return 0;
1367
1368         err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1369                                           tcp_nla_policy, NULL);
1370         if (err < 0)
1371                 return err;
1372
1373         if (tb[CTA_PROTOINFO_TCP_STATE] &&
1374             nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1375                 return -EINVAL;
1376
1377         spin_lock_bh(&ct->lock);
1378         if (tb[CTA_PROTOINFO_TCP_STATE])
1379                 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1380
1381         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1382                 struct nf_ct_tcp_flags *attr =
1383                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1384                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1385                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1386         }
1387
1388         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1389                 struct nf_ct_tcp_flags *attr =
1390                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1391                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1392                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1393         }
1394
1395         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1396             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1397             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1398             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1399                 ct->proto.tcp.seen[0].td_scale =
1400                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1401                 ct->proto.tcp.seen[1].td_scale =
1402                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1403         }
1404         spin_unlock_bh(&ct->lock);
1405
1406         return 0;
1407 }
1408
1409 static unsigned int tcp_nlattr_tuple_size(void)
1410 {
1411         static unsigned int size __read_mostly;
1412
1413         if (!size)
1414                 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1415
1416         return size;
1417 }
1418 #endif
1419
1420 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1421
1422 #include <linux/netfilter/nfnetlink.h>
1423 #include <linux/netfilter/nfnetlink_cttimeout.h>
1424
1425 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1426                                      struct net *net, void *data)
1427 {
1428         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1429         unsigned int *timeouts = data;
1430         int i;
1431
1432         if (!timeouts)
1433                 timeouts = tn->timeouts;
1434         /* set default TCP timeouts. */
1435         for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1436                 timeouts[i] = tn->timeouts[i];
1437
1438         if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1439                 timeouts[TCP_CONNTRACK_SYN_SENT] =
1440                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1441         }
1442
1443         if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1444                 timeouts[TCP_CONNTRACK_SYN_RECV] =
1445                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1446         }
1447         if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1448                 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1449                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1450         }
1451         if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1452                 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1453                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1454         }
1455         if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1456                 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1457                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1458         }
1459         if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1460                 timeouts[TCP_CONNTRACK_LAST_ACK] =
1461                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1462         }
1463         if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1464                 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1465                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1466         }
1467         if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1468                 timeouts[TCP_CONNTRACK_CLOSE] =
1469                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1470         }
1471         if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1472                 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1473                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1474         }
1475         if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1476                 timeouts[TCP_CONNTRACK_RETRANS] =
1477                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1478         }
1479         if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1480                 timeouts[TCP_CONNTRACK_UNACK] =
1481                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1482         }
1483
1484         timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1485         return 0;
1486 }
1487
1488 static int
1489 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1490 {
1491         const unsigned int *timeouts = data;
1492
1493         if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1494                         htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1495             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1496                          htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1497             nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1498                          htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1499             nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1500                          htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1501             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1502                          htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1503             nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1504                          htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1505             nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1506                          htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1507             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1508                          htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1509             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1510                          htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1511             nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1512                          htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1513             nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1514                          htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1515                 goto nla_put_failure;
1516         return 0;
1517
1518 nla_put_failure:
1519         return -ENOSPC;
1520 }
1521
1522 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1523         [CTA_TIMEOUT_TCP_SYN_SENT]      = { .type = NLA_U32 },
1524         [CTA_TIMEOUT_TCP_SYN_RECV]      = { .type = NLA_U32 },
1525         [CTA_TIMEOUT_TCP_ESTABLISHED]   = { .type = NLA_U32 },
1526         [CTA_TIMEOUT_TCP_FIN_WAIT]      = { .type = NLA_U32 },
1527         [CTA_TIMEOUT_TCP_CLOSE_WAIT]    = { .type = NLA_U32 },
1528         [CTA_TIMEOUT_TCP_LAST_ACK]      = { .type = NLA_U32 },
1529         [CTA_TIMEOUT_TCP_TIME_WAIT]     = { .type = NLA_U32 },
1530         [CTA_TIMEOUT_TCP_CLOSE]         = { .type = NLA_U32 },
1531         [CTA_TIMEOUT_TCP_SYN_SENT2]     = { .type = NLA_U32 },
1532         [CTA_TIMEOUT_TCP_RETRANS]       = { .type = NLA_U32 },
1533         [CTA_TIMEOUT_TCP_UNACK]         = { .type = NLA_U32 },
1534 };
1535 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1536
1537 void nf_conntrack_tcp_init_net(struct net *net)
1538 {
1539         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1540         int i;
1541
1542         for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1543                 tn->timeouts[i] = tcp_timeouts[i];
1544
1545         /* timeouts[0] is unused, make it same as SYN_SENT so
1546          * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1547          */
1548         tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1549
1550         /* If it is set to zero, we disable picking up already established
1551          * connections.
1552          */
1553         tn->tcp_loose = 1;
1554
1555         /* "Be conservative in what you do,
1556          *  be liberal in what you accept from others."
1557          * If it's non-zero, we mark only out of window RST segments as INVALID.
1558          */
1559         tn->tcp_be_liberal = 0;
1560
1561         /* If it's non-zero, we turn off RST sequence number check */
1562         tn->tcp_ignore_invalid_rst = 0;
1563
1564         /* Max number of the retransmitted packets without receiving an (acceptable)
1565          * ACK from the destination. If this number is reached, a shorter timer
1566          * will be started.
1567          */
1568         tn->tcp_max_retrans = 3;
1569
1570 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
1571         tn->offload_timeout = 30 * HZ;
1572 #endif
1573 }
1574
1575 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1576 {
1577         .l4proto                = IPPROTO_TCP,
1578 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1579         .print_conntrack        = tcp_print_conntrack,
1580 #endif
1581         .can_early_drop         = tcp_can_early_drop,
1582 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1583         .to_nlattr              = tcp_to_nlattr,
1584         .from_nlattr            = nlattr_to_tcp,
1585         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1586         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1587         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1588         .nlattr_size            = TCP_NLATTR_SIZE,
1589         .nla_policy             = nf_ct_port_nla_policy,
1590 #endif
1591 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1592         .ctnl_timeout           = {
1593                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1594                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1595                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1596                 .obj_size       = sizeof(unsigned int) *
1597                                         TCP_CONNTRACK_TIMEOUT_MAX,
1598                 .nla_policy     = tcp_timeout_nla_policy,
1599         },
1600 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1601 };