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                             enum ip_conntrack_dir dir)
 462 {
 463         /* SYN-ACK in reply to a SYN
 464          * or SYN from reply direction in simultaneous open.
 465          */
 466         sender->td_end =
 467         sender->td_maxend = end;
 468         sender->td_maxwin = (win == 0 ? 1 : win);
 469
 470         tcp_options(skb, dataoff, tcph, sender);
 471         /* RFC 1323:
 472          * Both sides must send the Window Scale option
 473          * to enable window scaling in either direction.
 474          */
 475         if (dir == IP_CT_DIR_REPLY &&
 476             !(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
 477               receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) {
 478                 sender->td_scale = 0;
 479                 receiver->td_scale = 0;
 480         }
 481 }
 482
 483 __printf(6, 7)
 484 static enum nf_ct_tcp_action nf_tcp_log_invalid(const struct sk_buff *skb,
 485                                                 const struct nf_conn *ct,
 486                                                 const struct nf_hook_state *state,
 487                                                 const struct ip_ct_tcp_state *sender,
 488                                                 enum nf_ct_tcp_action ret,
 489                                                 const char *fmt, ...)
 490 {
 491         const struct nf_tcp_net *tn = nf_tcp_pernet(nf_ct_net(ct));
 492         struct va_format vaf;
 493         va_list args;
 494         bool be_liberal;
 495
 496         be_liberal = sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || tn->tcp_be_liberal;
 497         if (be_liberal)
 498                 return NFCT_TCP_ACCEPT;
 499
 500         va_start(args, fmt);
 501         vaf.fmt = fmt;
 502         vaf.va = &args;
 503         nf_ct_l4proto_log_invalid(skb, ct, state, "%pV", &vaf);
 504         va_end(args);
 505
 506         return ret;
 507 }
 508
 509 static enum nf_ct_tcp_action
 510 tcp_in_window(struct nf_conn *ct, enum ip_conntrack_dir dir,
 511               unsigned int index, const struct sk_buff *skb,
 512               unsigned int dataoff, const struct tcphdr *tcph,
 513               const struct nf_hook_state *hook_state)
 514 {
 515         struct ip_ct_tcp *state = &ct->proto.tcp;
 516         struct ip_ct_tcp_state *sender = &state->seen[dir];
 517         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 518         __u32 seq, ack, sack, end, win, swin;
 519         bool in_recv_win, seq_ok;
 520         s32 receiver_offset;
 521         u16 win_raw;
 522
 523         /*
 524          * Get the required data from the packet.
 525          */
 526         seq = ntohl(tcph->seq);
 527         ack = sack = ntohl(tcph->ack_seq);
 528         win_raw = ntohs(tcph->window);
 529         win = win_raw;
 530         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
 531
 532         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
 533                 tcp_sack(skb, dataoff, tcph, &sack);
 534
 535         /* Take into account NAT sequence number mangling */
 536         receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
 537         ack -= receiver_offset;
 538         sack -= receiver_offset;
 539
 540         if (sender->td_maxwin == 0) {
 541                 /*
 542                  * Initialize sender data.
 543                  */
 544                 if (tcph->syn) {
 545                         tcp_init_sender(sender, receiver,
 546                                         skb, dataoff, tcph,
 547                                         end, win, dir);
 548                         if (!tcph->ack)
 549                                 /* Simultaneous open */
 550                                 return NFCT_TCP_ACCEPT;
 551                 } else {
 552                         /*
 553                          * We are in the middle of a connection,
 554                          * its history is lost for us.
 555                          * Let's try to use the data from the packet.
 556                          */
 557                         sender->td_end = end;
 558                         swin = win << sender->td_scale;
 559                         sender->td_maxwin = (swin == 0 ? 1 : swin);
 560                         sender->td_maxend = end + sender->td_maxwin;
 561                         if (receiver->td_maxwin == 0) {
 562                                 /* We haven't seen traffic in the other
 563                                  * direction yet but we have to tweak window
 564                                  * tracking to pass III and IV until that
 565                                  * happens.
 566                                  */
 567                                 receiver->td_end = receiver->td_maxend = sack;
 568                         } else if (sack == receiver->td_end + 1) {
 569                                 /* Likely a reply to a keepalive.
 570                                  * Needed for III.
 571                                  */
 572                                 receiver->td_end++;
 573                         }
 574
 575                 }
 576         } else if (tcph->syn &&
 577                    after(end, sender->td_end) &&
 578                    (state->state == TCP_CONNTRACK_SYN_SENT ||
 579                     state->state == TCP_CONNTRACK_SYN_RECV)) {
 580                 /*
 581                  * RFC 793: "if a TCP is reinitialized ... then it need
 582                  * not wait at all; it must only be sure to use sequence
 583                  * numbers larger than those recently used."
 584                  *
 585                  * Re-init state for this direction, just like for the first
 586                  * syn(-ack) reply, it might differ in seq, ack or tcp options.
 587                  */
 588                 tcp_init_sender(sender, receiver,
 589                                 skb, dataoff, tcph,
 590                                 end, win, dir);
 591
 592                 if (dir == IP_CT_DIR_REPLY && !tcph->ack)
 593                         return NFCT_TCP_ACCEPT;
 594         }
 595
 596         if (!(tcph->ack)) {
 597                 /*
 598                  * If there is no ACK, just pretend it was set and OK.
 599                  */
 600                 ack = sack = receiver->td_end;
 601         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
 602                     (TCP_FLAG_ACK|TCP_FLAG_RST))
 603                    && (ack == 0)) {
 604                 /*
 605                  * Broken TCP stacks, that set ACK in RST packets as well
 606                  * with zero ack value.
 607                  */
 608                 ack = sack = receiver->td_end;
 609         }
 610
 611         if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
 612                 /*
 613                  * RST sent answering SYN.
 614                  */
 615                 seq = end = sender->td_end;
 616
 617         seq_ok = before(seq, sender->td_maxend + 1);
 618         if (!seq_ok) {
 619                 u32 overshot = end - sender->td_maxend + 1;
 620                 bool ack_ok;
 621
 622                 ack_ok = after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1);
 623                 in_recv_win = receiver->td_maxwin &&
 624                               after(end, sender->td_end - receiver->td_maxwin - 1);
 625
 626                 if (in_recv_win &&
 627                     ack_ok &&
 628                     overshot <= receiver->td_maxwin &&
 629                     before(sack, receiver->td_end + 1)) {
 630                         /* Work around TCPs that send more bytes than allowed by
 631                          * the receive window.
 632                          *
 633                          * If the (marked as invalid) packet is allowed to pass by
 634                          * the ruleset and the peer acks this data, then its possible
 635                          * all future packets will trigger 'ACK is over upper bound' check.
 636                          *
 637                          * Thus if only the sequence check fails then do update td_end so
 638                          * possible ACK for this data can update internal state.
 639                          */
 640                         sender->td_end = end;
 641                         sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 642
 643                         return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 644                                                   "%u bytes more than expected", overshot);
 645                 }
 646
 647                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
 648                                           "SEQ is over upper bound %u (over the window of the receiver)",
 649                                           sender->td_maxend + 1);
 650         }
 651
 652         if (!before(sack, receiver->td_end + 1))
 653                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
 654                                           "ACK is over upper bound %u (ACKed data not seen yet)",
 655                                           receiver->td_end + 1);
 656
 657         /* Is the ending sequence in the receive window (if available)? */
 658         in_recv_win = !receiver->td_maxwin ||
 659                       after(end, sender->td_end - receiver->td_maxwin - 1);
 660         if (!in_recv_win)
 661                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 662                                           "SEQ is under lower bound %u (already ACKed data retransmitted)",
 663                                           sender->td_end - receiver->td_maxwin - 1);
 664         if (!after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1))
 665                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 666                                           "ignored ACK under lower bound %u (possible overly delayed)",
 667                                           receiver->td_end - MAXACKWINDOW(sender) - 1);
 668
 669         /* Take into account window scaling (RFC 1323). */
 670         if (!tcph->syn)
 671                 win <<= sender->td_scale;
 672
 673         /* Update sender data. */
 674         swin = win + (sack - ack);
 675         if (sender->td_maxwin < swin)
 676                 sender->td_maxwin = swin;
 677         if (after(end, sender->td_end)) {
 678                 sender->td_end = end;
 679                 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 680         }
 681         if (tcph->ack) {
 682                 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
 683                         sender->td_maxack = ack;
 684                         sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
 685                 } else if (after(ack, sender->td_maxack)) {
 686                         sender->td_maxack = ack;
 687                 }
 688         }
 689
 690         /* Update receiver data. */
 691         if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
 692                 receiver->td_maxwin += end - sender->td_maxend;
 693         if (after(sack + win, receiver->td_maxend - 1)) {
 694                 receiver->td_maxend = sack + win;
 695                 if (win == 0)
 696                         receiver->td_maxend++;
 697         }
 698         if (ack == receiver->td_end)
 699                 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 700
 701         /* Check retransmissions. */
 702         if (index == TCP_ACK_SET) {
 703                 if (state->last_dir == dir &&
 704                     state->last_seq == seq &&
 705                     state->last_ack == ack &&
 706                     state->last_end == end &&
 707                     state->last_win == win_raw) {
 708                         state->retrans++;
 709                 } else {
 710                         state->last_dir = dir;
 711                         state->last_seq = seq;
 712                         state->last_ack = ack;
 713                         state->last_end = end;
 714                         state->last_win = win_raw;
 715                         state->retrans = 0;
 716                 }
 717         }
 718
 719         return NFCT_TCP_ACCEPT;
 720 }
 721
 722 static void __cold nf_tcp_handle_invalid(struct nf_conn *ct,
 723                                          enum ip_conntrack_dir dir,
 724                                          int index,
 725                                          const struct sk_buff *skb,
 726                                          const struct nf_hook_state *hook_state)
 727 {
 728         const unsigned int *timeouts;
 729         const struct nf_tcp_net *tn;
 730         unsigned int timeout;
 731         u32 expires;
 732
 733         if (!test_bit(IPS_ASSURED_BIT, &ct->status) ||
 734             test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
 735                 return;
 736
 737         /* We don't want to have connections hanging around in ESTABLISHED
 738          * state for long time 'just because' conntrack deemed a FIN/RST
 739          * out-of-window.
 740          *
 741          * Shrink the timeout just like when there is unacked data.
 742          * This speeds up eviction of 'dead' connections where the
 743          * connection and conntracks internal state are out of sync.
 744          */
 745         switch (index) {
 746         case TCP_RST_SET:
 747         case TCP_FIN_SET:
 748                 break;
 749         default:
 750                 return;
 751         }
 752
 753         if (ct->proto.tcp.last_dir != dir &&
 754             (ct->proto.tcp.last_index == TCP_FIN_SET ||
 755              ct->proto.tcp.last_index == TCP_RST_SET)) {
 756                 expires = nf_ct_expires(ct);
 757                 if (expires < 120 * HZ)
 758                         return;
 759
 760                 tn = nf_tcp_pernet(nf_ct_net(ct));
 761                 timeouts = nf_ct_timeout_lookup(ct);
 762                 if (!timeouts)
 763                         timeouts = tn->timeouts;
 764
 765                 timeout = READ_ONCE(timeouts[TCP_CONNTRACK_UNACK]);
 766                 if (expires > timeout) {
 767                         nf_ct_l4proto_log_invalid(skb, ct, hook_state,
 768                                           "packet (index %d, dir %d) response for index %d lower timeout to %u",
 769                                           index, dir, ct->proto.tcp.last_index, timeout);
 770
 771                         WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp);
 772                 }
 773         } else {
 774                 ct->proto.tcp.last_index = index;
 775                 ct->proto.tcp.last_dir = dir;
 776         }
 777 }
 778
 779 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
 780 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
 781                                  TCPHDR_URG) + 1] =
 782 {
 783         [TCPHDR_SYN]                            = 1,
 784         [TCPHDR_SYN|TCPHDR_URG]                 = 1,
 785         [TCPHDR_SYN|TCPHDR_ACK]                 = 1,
 786         [TCPHDR_RST]                            = 1,
 787         [TCPHDR_RST|TCPHDR_ACK]                 = 1,
 788         [TCPHDR_FIN|TCPHDR_ACK]                 = 1,
 789         [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG]      = 1,
 790         [TCPHDR_ACK]                            = 1,
 791         [TCPHDR_ACK|TCPHDR_URG]                 = 1,
 792 };
 793
 794 static void tcp_error_log(const struct sk_buff *skb,
 795                           const struct nf_hook_state *state,
 796                           const char *msg)
 797 {
 798         nf_l4proto_log_invalid(skb, state, IPPROTO_TCP, "%s", msg);
 799 }
 800
 801 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
 802 static bool tcp_error(const struct tcphdr *th,
 803                       struct sk_buff *skb,
 804                       unsigned int dataoff,
 805                       const struct nf_hook_state *state)
 806 {
 807         unsigned int tcplen = skb->len - dataoff;
 808         u8 tcpflags;
 809
 810         /* Not whole TCP header or malformed packet */
 811         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
 812                 tcp_error_log(skb, state, "truncated packet");
 813                 return true;
 814         }
 815
 816         /* Checksum invalid? Ignore.
 817          * We skip checking packets on the outgoing path
 818          * because the checksum is assumed to be correct.
 819          */
 820         /* FIXME: Source route IP option packets --RR */
 821         if (state->net->ct.sysctl_checksum &&
 822             state->hook == NF_INET_PRE_ROUTING &&
 823             nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
 824                 tcp_error_log(skb, state, "bad checksum");
 825                 return true;
 826         }
 827
 828         /* Check TCP flags. */
 829         tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
 830         if (!tcp_valid_flags[tcpflags]) {
 831                 tcp_error_log(skb, state, "invalid tcp flag combination");
 832                 return true;
 833         }
 834
 835         return false;
 836 }
 837
 838 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
 839                              unsigned int dataoff,
 840                              const struct tcphdr *th)
 841 {
 842         enum tcp_conntrack new_state;
 843         struct net *net = nf_ct_net(ct);
 844         const struct nf_tcp_net *tn = nf_tcp_pernet(net);
 845
 846         /* Don't need lock here: this conntrack not in circulation yet */
 847         new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
 848
 849         /* Invalid: delete conntrack */
 850         if (new_state >= TCP_CONNTRACK_MAX) {
 851                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
 852                 return false;
 853         }
 854
 855         if (new_state == TCP_CONNTRACK_SYN_SENT) {
 856                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 857                 /* SYN packet */
 858                 ct->proto.tcp.seen[0].td_end =
 859                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 860                                              dataoff, th);
 861                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 862                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 863                         ct->proto.tcp.seen[0].td_maxwin = 1;
 864                 ct->proto.tcp.seen[0].td_maxend =
 865                         ct->proto.tcp.seen[0].td_end;
 866
 867                 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
 868         } else if (tn->tcp_loose == 0) {
 869                 /* Don't try to pick up connections. */
 870                 return false;
 871         } else {
 872                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 873                 /*
 874                  * We are in the middle of a connection,
 875                  * its history is lost for us.
 876                  * Let's try to use the data from the packet.
 877                  */
 878                 ct->proto.tcp.seen[0].td_end =
 879                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 880                                              dataoff, th);
 881                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 882                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 883                         ct->proto.tcp.seen[0].td_maxwin = 1;
 884                 ct->proto.tcp.seen[0].td_maxend =
 885                         ct->proto.tcp.seen[0].td_end +
 886                         ct->proto.tcp.seen[0].td_maxwin;
 887
 888                 /* We assume SACK and liberal window checking to handle
 889                  * window scaling */
 890                 ct->proto.tcp.seen[0].flags =
 891                 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
 892                                               IP_CT_TCP_FLAG_BE_LIBERAL;
 893         }
 894
 895         /* tcp_packet will set them */
 896         ct->proto.tcp.last_index = TCP_NONE_SET;
 897         return true;
 898 }
 899
 900 static bool tcp_can_early_drop(const struct nf_conn *ct)
 901 {
 902         switch (ct->proto.tcp.state) {
 903         case TCP_CONNTRACK_FIN_WAIT:
 904         case TCP_CONNTRACK_LAST_ACK:
 905         case TCP_CONNTRACK_TIME_WAIT:
 906         case TCP_CONNTRACK_CLOSE:
 907         case TCP_CONNTRACK_CLOSE_WAIT:
 908                 return true;
 909         default:
 910                 break;
 911         }
 912
 913         return false;
 914 }
 915
 916 void nf_conntrack_tcp_set_closing(struct nf_conn *ct)
 917 {
 918         enum tcp_conntrack old_state;
 919         const unsigned int *timeouts;
 920         u32 timeout;
 921
 922         if (!nf_ct_is_confirmed(ct))
 923                 return;
 924
 925         spin_lock_bh(&ct->lock);
 926         old_state = ct->proto.tcp.state;
 927         ct->proto.tcp.state = TCP_CONNTRACK_CLOSE;
 928
 929         if (old_state == TCP_CONNTRACK_CLOSE ||
 930             test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) {
 931                 spin_unlock_bh(&ct->lock);
 932                 return;
 933         }
 934
 935         timeouts = nf_ct_timeout_lookup(ct);
 936         if (!timeouts) {
 937                 const struct nf_tcp_net *tn;
 938
 939                 tn = nf_tcp_pernet(nf_ct_net(ct));
 940                 timeouts = tn->timeouts;
 941         }
 942
 943         timeout = timeouts[TCP_CONNTRACK_CLOSE];
 944         WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp);
 945
 946         spin_unlock_bh(&ct->lock);
 947
 948         nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
 949 }
 950
 951 static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state)
 952 {
 953         state->td_end           = 0;
 954         state->td_maxend        = 0;
 955         state->td_maxwin        = 0;
 956         state->td_maxack        = 0;
 957         state->td_scale         = 0;
 958         state->flags            &= IP_CT_TCP_FLAG_BE_LIBERAL;
 959 }
 960
 961 /* Returns verdict for packet, or -1 for invalid. */
 962 int nf_conntrack_tcp_packet(struct nf_conn *ct,
 963                             struct sk_buff *skb,
 964                             unsigned int dataoff,
 965                             enum ip_conntrack_info ctinfo,
 966                             const struct nf_hook_state *state)
 967 {
 968         struct net *net = nf_ct_net(ct);
 969         struct nf_tcp_net *tn = nf_tcp_pernet(net);
 970         enum tcp_conntrack new_state, old_state;
 971         unsigned int index, *timeouts;
 972         enum nf_ct_tcp_action res;
 973         enum ip_conntrack_dir dir;
 974         const struct tcphdr *th;
 975         struct tcphdr _tcph;
 976         unsigned long timeout;
 977
 978         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 979         if (th == NULL)
 980                 return -NF_ACCEPT;
 981
 982         if (tcp_error(th, skb, dataoff, state))
 983                 return -NF_ACCEPT;
 984
 985         if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
 986                 return -NF_ACCEPT;
 987
 988         spin_lock_bh(&ct->lock);
 989         old_state = ct->proto.tcp.state;
 990         dir = CTINFO2DIR(ctinfo);
 991         index = get_conntrack_index(th);
 992         new_state = tcp_conntracks[dir][index][old_state];
 993
 994         switch (new_state) {
 995         case TCP_CONNTRACK_SYN_SENT:
 996                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 997                         break;
 998                 /* RFC 1122: "When a connection is closed actively,
 999                  * it MUST linger in TIME-WAIT state for a time 2xMSL
1000                  * (Maximum Segment Lifetime). However, it MAY accept
1001                  * a new SYN from the remote TCP to reopen the connection
1002                  * directly from TIME-WAIT state, if..."
1003                  * We ignore the conditions because we are in the
1004                  * TIME-WAIT state anyway.
1005                  *
1006                  * Handle aborted connections: we and the server
1007                  * think there is an existing connection but the client
1008                  * aborts it and starts a new one.
1009                  */
1010                 if (((ct->proto.tcp.seen[dir].flags
1011                       | ct->proto.tcp.seen[!dir].flags)
1012                      & IP_CT_TCP_FLAG_CLOSE_INIT)
1013                     || (ct->proto.tcp.last_dir == dir
1014                         && ct->proto.tcp.last_index == TCP_RST_SET)) {
1015                         /* Attempt to reopen a closed/aborted connection.
1016                          * Delete this connection and look up again. */
1017                         spin_unlock_bh(&ct->lock);
1018
1019                         /* Only repeat if we can actually remove the timer.
1020                          * Destruction may already be in progress in process
1021                          * context and we must give it a chance to terminate.
1022                          */
1023                         if (nf_ct_kill(ct))
1024                                 return -NF_REPEAT;
1025                         return NF_DROP;
1026                 }
1027                 fallthrough;
1028         case TCP_CONNTRACK_IGNORE:
1029                 /* Ignored packets:
1030                  *
1031                  * Our connection entry may be out of sync, so ignore
1032                  * packets which may signal the real connection between
1033                  * the client and the server.
1034                  *
1035                  * a) SYN in ORIGINAL
1036                  * b) SYN/ACK in REPLY
1037                  * c) ACK in reply direction after initial SYN in original.
1038                  *
1039                  * If the ignored packet is invalid, the receiver will send
1040                  * a RST we'll catch below.
1041                  */
1042                 if (index == TCP_SYNACK_SET
1043                     && ct->proto.tcp.last_index == TCP_SYN_SET
1044                     && ct->proto.tcp.last_dir != dir
1045                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1046                         /* b) This SYN/ACK acknowledges a SYN that we earlier
1047                          * ignored as invalid. This means that the client and
1048                          * the server are both in sync, while the firewall is
1049                          * not. We get in sync from the previously annotated
1050                          * values.
1051                          */
1052                         old_state = TCP_CONNTRACK_SYN_SENT;
1053                         new_state = TCP_CONNTRACK_SYN_RECV;
1054                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
1055                                 ct->proto.tcp.last_end;
1056                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
1057                                 ct->proto.tcp.last_end;
1058                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
1059                                 ct->proto.tcp.last_win == 0 ?
1060                                         1 : ct->proto.tcp.last_win;
1061                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
1062                                 ct->proto.tcp.last_wscale;
1063                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1064                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
1065                                 ct->proto.tcp.last_flags;
1066                         nf_ct_tcp_state_reset(&ct->proto.tcp.seen[dir]);
1067                         break;
1068                 }
1069                 ct->proto.tcp.last_index = index;
1070                 ct->proto.tcp.last_dir = dir;
1071                 ct->proto.tcp.last_seq = ntohl(th->seq);
1072                 ct->proto.tcp.last_end =
1073                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
1074                 ct->proto.tcp.last_win = ntohs(th->window);
1075
1076                 /* a) This is a SYN in ORIGINAL. The client and the server
1077                  * may be in sync but we are not. In that case, we annotate
1078                  * the TCP options and let the packet go through. If it is a
1079                  * valid SYN packet, the server will reply with a SYN/ACK, and
1080                  * then we'll get in sync. Otherwise, the server potentially
1081                  * responds with a challenge ACK if implementing RFC5961.
1082                  */
1083                 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
1084                         struct ip_ct_tcp_state seen = {};
1085
1086                         ct->proto.tcp.last_flags =
1087                         ct->proto.tcp.last_wscale = 0;
1088                         tcp_options(skb, dataoff, th, &seen);
1089                         if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1090                                 ct->proto.tcp.last_flags |=
1091                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
1092                                 ct->proto.tcp.last_wscale = seen.td_scale;
1093                         }
1094                         if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
1095                                 ct->proto.tcp.last_flags |=
1096                                         IP_CT_TCP_FLAG_SACK_PERM;
1097                         }
1098                         /* Mark the potential for RFC5961 challenge ACK,
1099                          * this pose a special problem for LAST_ACK state
1100                          * as ACK is intrepretated as ACKing last FIN.
1101                          */
1102                         if (old_state == TCP_CONNTRACK_LAST_ACK)
1103                                 ct->proto.tcp.last_flags |=
1104                                         IP_CT_EXP_CHALLENGE_ACK;
1105                 }
1106
1107                 /* possible challenge ack reply to syn */
1108                 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1109                     index == TCP_ACK_SET &&
1110                     dir == IP_CT_DIR_REPLY)
1111                         ct->proto.tcp.last_ack = ntohl(th->ack_seq);
1112
1113                 spin_unlock_bh(&ct->lock);
1114                 nf_ct_l4proto_log_invalid(skb, ct, state,
1115                                           "packet (index %d) in dir %d ignored, state %s",
1116                                           index, dir,
1117                                           tcp_conntrack_names[old_state]);
1118                 return NF_ACCEPT;
1119         case TCP_CONNTRACK_MAX:
1120                 /* Special case for SYN proxy: when the SYN to the server or
1121                  * the SYN/ACK from the server is lost, the client may transmit
1122                  * a keep-alive packet while in SYN_SENT state. This needs to
1123                  * be associated with the original conntrack entry in order to
1124                  * generate a new SYN with the correct sequence number.
1125                  */
1126                 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
1127                     index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
1128                     ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1129                     ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1130                         pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1131                         spin_unlock_bh(&ct->lock);
1132                         return NF_ACCEPT;
1133                 }
1134
1135                 /* Invalid packet */
1136                 spin_unlock_bh(&ct->lock);
1137                 nf_ct_l4proto_log_invalid(skb, ct, state,
1138                                           "packet (index %d) in dir %d invalid, state %s",
1139                                           index, dir,
1140                                           tcp_conntrack_names[old_state]);
1141                 return -NF_ACCEPT;
1142         case TCP_CONNTRACK_TIME_WAIT:
1143                 /* RFC5961 compliance cause stack to send "challenge-ACK"
1144                  * e.g. in response to spurious SYNs.  Conntrack MUST
1145                  * not believe this ACK is acking last FIN.
1146                  */
1147                 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1148                     index == TCP_ACK_SET &&
1149                     ct->proto.tcp.last_dir != dir &&
1150                     ct->proto.tcp.last_index == TCP_SYN_SET &&
1151                     (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1152                         /* Detected RFC5961 challenge ACK */
1153                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1154                         spin_unlock_bh(&ct->lock);
1155                         nf_ct_l4proto_log_invalid(skb, ct, state, "challenge-ack ignored");
1156                         return NF_ACCEPT; /* Don't change state */
1157                 }
1158                 break;
1159         case TCP_CONNTRACK_SYN_SENT2:
1160                 /* tcp_conntracks table is not smart enough to handle
1161                  * simultaneous open.
1162                  */
1163                 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1164                 break;
1165         case TCP_CONNTRACK_SYN_RECV:
1166                 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1167                     ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1168                         new_state = TCP_CONNTRACK_ESTABLISHED;
1169                 break;
1170         case TCP_CONNTRACK_CLOSE:
1171                 if (index != TCP_RST_SET)
1172                         break;
1173
1174                 /* If we are closing, tuple might have been re-used already.
1175                  * last_index, last_ack, and all other ct fields used for
1176                  * sequence/window validation are outdated in that case.
1177                  *
1178                  * As the conntrack can already be expired by GC under pressure,
1179                  * just skip validation checks.
1180                  */
1181                 if (tcp_can_early_drop(ct))
1182                         goto in_window;
1183
1184                 /* td_maxack might be outdated if we let a SYN through earlier */
1185                 if ((ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) &&
1186                     ct->proto.tcp.last_index != TCP_SYN_SET) {
1187                         u32 seq = ntohl(th->seq);
1188
1189                         /* If we are not in established state and SEQ=0 this is most
1190                          * likely an answer to a SYN we let go through above (last_index
1191                          * can be updated due to out-of-order ACKs).
1192                          */
1193                         if (seq == 0 && !nf_conntrack_tcp_established(ct))
1194                                 break;
1195
1196                         if (before(seq, ct->proto.tcp.seen[!dir].td_maxack) &&
1197                             !tn->tcp_ignore_invalid_rst) {
1198                                 /* Invalid RST  */
1199                                 spin_unlock_bh(&ct->lock);
1200                                 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid rst");
1201                                 return -NF_ACCEPT;
1202                         }
1203
1204                         if (!nf_conntrack_tcp_established(ct) ||
1205                             seq == ct->proto.tcp.seen[!dir].td_maxack)
1206                                 break;
1207
1208                         /* Check if rst is part of train, such as
1209                          *   foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1210                          *   foo:80 > bar:4379: R, 235946602:235946602(0)  ack 42
1211                          */
1212                         if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1213                             ct->proto.tcp.last_dir == dir &&
1214                             seq == ct->proto.tcp.last_end)
1215                                 break;
1216
1217                         /* ... RST sequence number doesn't match exactly, keep
1218                          * established state to allow a possible challenge ACK.
1219                          */
1220                         new_state = old_state;
1221                 }
1222                 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1223                          && ct->proto.tcp.last_index == TCP_SYN_SET)
1224                         || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1225                             && ct->proto.tcp.last_index == TCP_ACK_SET))
1226                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1227                         /* RST sent to invalid SYN or ACK we had let through
1228                          * at a) and c) above:
1229                          *
1230                          * a) SYN was in window then
1231                          * c) we hold a half-open connection.
1232                          *
1233                          * Delete our connection entry.
1234                          * We skip window checking, because packet might ACK
1235                          * segments we ignored. */
1236                         goto in_window;
1237                 }
1238
1239                 /* Reset in response to a challenge-ack we let through earlier */
1240                 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1241                     ct->proto.tcp.last_index == TCP_ACK_SET &&
1242                     ct->proto.tcp.last_dir == IP_CT_DIR_REPLY &&
1243                     ntohl(th->seq) == ct->proto.tcp.last_ack)
1244                         goto in_window;
1245
1246                 break;
1247         default:
1248                 /* Keep compilers happy. */
1249                 break;
1250         }
1251
1252         res = tcp_in_window(ct, dir, index,
1253                             skb, dataoff, th, state);
1254         switch (res) {
1255         case NFCT_TCP_IGNORE:
1256                 spin_unlock_bh(&ct->lock);
1257                 return NF_ACCEPT;
1258         case NFCT_TCP_INVALID:
1259                 nf_tcp_handle_invalid(ct, dir, index, skb, state);
1260                 spin_unlock_bh(&ct->lock);
1261                 return -NF_ACCEPT;
1262         case NFCT_TCP_ACCEPT:
1263                 break;
1264         }
1265      in_window:
1266         /* From now on we have got in-window packets */
1267         ct->proto.tcp.last_index = index;
1268         ct->proto.tcp.last_dir = dir;
1269
1270         ct->proto.tcp.state = new_state;
1271         if (old_state != new_state
1272             && new_state == TCP_CONNTRACK_FIN_WAIT)
1273                 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1274
1275         timeouts = nf_ct_timeout_lookup(ct);
1276         if (!timeouts)
1277                 timeouts = tn->timeouts;
1278
1279         if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1280             timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1281                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1282         else if (unlikely(index == TCP_RST_SET))
1283                 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1284         else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1285                  IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1286                  timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1287                 timeout = timeouts[TCP_CONNTRACK_UNACK];
1288         else if (ct->proto.tcp.last_win == 0 &&
1289                  timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1290                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1291         else
1292                 timeout = timeouts[new_state];
1293         spin_unlock_bh(&ct->lock);
1294
1295         if (new_state != old_state)
1296                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1297
1298         if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1299                 /* If only reply is a RST, we can consider ourselves not to
1300                    have an established connection: this is a fairly common
1301                    problem case, so we can delete the conntrack
1302                    immediately.  --RR */
1303                 if (th->rst) {
1304                         nf_ct_kill_acct(ct, ctinfo, skb);
1305                         return NF_ACCEPT;
1306                 }
1307
1308                 if (index == TCP_SYN_SET && old_state == TCP_CONNTRACK_SYN_SENT) {
1309                         /* do not renew timeout on SYN retransmit.
1310                          *
1311                          * Else port reuse by client or NAT middlebox can keep
1312                          * entry alive indefinitely (including nat info).
1313                          */
1314                         return NF_ACCEPT;
1315                 }
1316
1317                 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1318                  * pickup with loose=1. Avoid large ESTABLISHED timeout.
1319                  */
1320                 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1321                     timeout > timeouts[TCP_CONNTRACK_UNACK])
1322                         timeout = timeouts[TCP_CONNTRACK_UNACK];
1323         } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1324                    && (old_state == TCP_CONNTRACK_SYN_RECV
1325                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1326                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1327                 /* Set ASSURED if we see valid ack in ESTABLISHED
1328                    after SYN_RECV or a valid answer for a picked up
1329                    connection. */
1330                 set_bit(IPS_ASSURED_BIT, &ct->status);
1331                 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1332         }
1333         nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1334
1335         return NF_ACCEPT;
1336 }
1337
1338 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1339
1340 #include <linux/netfilter/nfnetlink.h>
1341 #include <linux/netfilter/nfnetlink_conntrack.h>
1342
1343 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1344                          struct nf_conn *ct, bool destroy)
1345 {
1346         struct nlattr *nest_parms;
1347         struct nf_ct_tcp_flags tmp = {};
1348
1349         spin_lock_bh(&ct->lock);
1350         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1351         if (!nest_parms)
1352                 goto nla_put_failure;
1353
1354         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1355                 goto nla_put_failure;
1356
1357         if (destroy)
1358                 goto skip_state;
1359
1360         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1361                        ct->proto.tcp.seen[0].td_scale) ||
1362             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1363                        ct->proto.tcp.seen[1].td_scale))
1364                 goto nla_put_failure;
1365
1366         tmp.flags = ct->proto.tcp.seen[0].flags;
1367         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1368                     sizeof(struct nf_ct_tcp_flags), &tmp))
1369                 goto nla_put_failure;
1370
1371         tmp.flags = ct->proto.tcp.seen[1].flags;
1372         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1373                     sizeof(struct nf_ct_tcp_flags), &tmp))
1374                 goto nla_put_failure;
1375 skip_state:
1376         spin_unlock_bh(&ct->lock);
1377         nla_nest_end(skb, nest_parms);
1378
1379         return 0;
1380
1381 nla_put_failure:
1382         spin_unlock_bh(&ct->lock);
1383         return -1;
1384 }
1385
1386 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1387         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1388         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1389         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1390         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1391         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len = sizeof(struct nf_ct_tcp_flags) },
1392 };
1393
1394 #define TCP_NLATTR_SIZE ( \
1395         NLA_ALIGN(NLA_HDRLEN + 1) + \
1396         NLA_ALIGN(NLA_HDRLEN + 1) + \
1397         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1398         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1399
1400 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1401 {
1402         struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1403         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1404         int err;
1405
1406         /* updates could not contain anything about the private
1407          * protocol info, in that case skip the parsing */
1408         if (!pattr)
1409                 return 0;
1410
1411         err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1412                                           tcp_nla_policy, NULL);
1413         if (err < 0)
1414                 return err;
1415
1416         if (tb[CTA_PROTOINFO_TCP_STATE] &&
1417             nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1418                 return -EINVAL;
1419
1420         spin_lock_bh(&ct->lock);
1421         if (tb[CTA_PROTOINFO_TCP_STATE])
1422                 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1423
1424         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1425                 struct nf_ct_tcp_flags *attr =
1426                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1427                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1428                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1429         }
1430
1431         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1432                 struct nf_ct_tcp_flags *attr =
1433                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1434                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1435                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1436         }
1437
1438         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1439             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1440             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1441             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1442                 ct->proto.tcp.seen[0].td_scale =
1443                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1444                 ct->proto.tcp.seen[1].td_scale =
1445                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1446         }
1447         spin_unlock_bh(&ct->lock);
1448
1449         return 0;
1450 }
1451
1452 static unsigned int tcp_nlattr_tuple_size(void)
1453 {
1454         static unsigned int size __read_mostly;
1455
1456         if (!size)
1457                 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1458
1459         return size;
1460 }
1461 #endif
1462
1463 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1464
1465 #include <linux/netfilter/nfnetlink.h>
1466 #include <linux/netfilter/nfnetlink_cttimeout.h>
1467
1468 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1469                                      struct net *net, void *data)
1470 {
1471         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1472         unsigned int *timeouts = data;
1473         int i;
1474
1475         if (!timeouts)
1476                 timeouts = tn->timeouts;
1477         /* set default TCP timeouts. */
1478         for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1479                 timeouts[i] = tn->timeouts[i];
1480
1481         if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1482                 timeouts[TCP_CONNTRACK_SYN_SENT] =
1483                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1484         }
1485
1486         if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1487                 timeouts[TCP_CONNTRACK_SYN_RECV] =
1488                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1489         }
1490         if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1491                 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1492                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1493         }
1494         if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1495                 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1496                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1497         }
1498         if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1499                 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1500                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1501         }
1502         if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1503                 timeouts[TCP_CONNTRACK_LAST_ACK] =
1504                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1505         }
1506         if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1507                 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1508                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1509         }
1510         if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1511                 timeouts[TCP_CONNTRACK_CLOSE] =
1512                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1513         }
1514         if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1515                 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1516                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1517         }
1518         if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1519                 timeouts[TCP_CONNTRACK_RETRANS] =
1520                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1521         }
1522         if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1523                 timeouts[TCP_CONNTRACK_UNACK] =
1524                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1525         }
1526
1527         timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1528         return 0;
1529 }
1530
1531 static int
1532 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1533 {
1534         const unsigned int *timeouts = data;
1535
1536         if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1537                         htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1538             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1539                          htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1540             nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1541                          htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1542             nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1543                          htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1544             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1545                          htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1546             nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1547                          htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1548             nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1549                          htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1550             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1551                          htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1552             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1553                          htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1554             nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1555                          htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1556             nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1557                          htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1558                 goto nla_put_failure;
1559         return 0;
1560
1561 nla_put_failure:
1562         return -ENOSPC;
1563 }
1564
1565 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1566         [CTA_TIMEOUT_TCP_SYN_SENT]      = { .type = NLA_U32 },
1567         [CTA_TIMEOUT_TCP_SYN_RECV]      = { .type = NLA_U32 },
1568         [CTA_TIMEOUT_TCP_ESTABLISHED]   = { .type = NLA_U32 },
1569         [CTA_TIMEOUT_TCP_FIN_WAIT]      = { .type = NLA_U32 },
1570         [CTA_TIMEOUT_TCP_CLOSE_WAIT]    = { .type = NLA_U32 },
1571         [CTA_TIMEOUT_TCP_LAST_ACK]      = { .type = NLA_U32 },
1572         [CTA_TIMEOUT_TCP_TIME_WAIT]     = { .type = NLA_U32 },
1573         [CTA_TIMEOUT_TCP_CLOSE]         = { .type = NLA_U32 },
1574         [CTA_TIMEOUT_TCP_SYN_SENT2]     = { .type = NLA_U32 },
1575         [CTA_TIMEOUT_TCP_RETRANS]       = { .type = NLA_U32 },
1576         [CTA_TIMEOUT_TCP_UNACK]         = { .type = NLA_U32 },
1577 };
1578 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1579
1580 void nf_conntrack_tcp_init_net(struct net *net)
1581 {
1582         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1583         int i;
1584
1585         for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1586                 tn->timeouts[i] = tcp_timeouts[i];
1587
1588         /* timeouts[0] is unused, make it same as SYN_SENT so
1589          * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1590          */
1591         tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1592
1593         /* If it is set to zero, we disable picking up already established
1594          * connections.
1595          */
1596         tn->tcp_loose = 1;
1597
1598         /* "Be conservative in what you do,
1599          *  be liberal in what you accept from others."
1600          * If it's non-zero, we mark only out of window RST segments as INVALID.
1601          */
1602         tn->tcp_be_liberal = 0;
1603
1604         /* If it's non-zero, we turn off RST sequence number check */
1605         tn->tcp_ignore_invalid_rst = 0;
1606
1607         /* Max number of the retransmitted packets without receiving an (acceptable)
1608          * ACK from the destination. If this number is reached, a shorter timer
1609          * will be started.
1610          */
1611         tn->tcp_max_retrans = 3;
1612
1613 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
1614         tn->offload_timeout = 30 * HZ;
1615 #endif
1616 }
1617
1618 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1619 {
1620         .l4proto                = IPPROTO_TCP,
1621 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1622         .print_conntrack        = tcp_print_conntrack,
1623 #endif
1624         .can_early_drop         = tcp_can_early_drop,
1625 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1626         .to_nlattr              = tcp_to_nlattr,
1627         .from_nlattr            = nlattr_to_tcp,
1628         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1629         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1630         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1631         .nlattr_size            = TCP_NLATTR_SIZE,
1632         .nla_policy             = nf_ct_port_nla_policy,
1633 #endif
1634 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1635         .ctnl_timeout           = {
1636                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1637                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1638                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1639                 .obj_size       = sizeof(unsigned int) *
1640                                         TCP_CONNTRACK_TIMEOUT_MAX,
1641                 .nla_policy     = tcp_timeout_nla_policy,
1642         },
1643 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1644 };