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         struct nf_conntrack_tuple *tuple;
 971         enum tcp_conntrack new_state, old_state;
 972         unsigned int index, *timeouts;
 973         enum nf_ct_tcp_action res;
 974         enum ip_conntrack_dir dir;
 975         const struct tcphdr *th;
 976         struct tcphdr _tcph;
 977         unsigned long timeout;
 978
 979         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 980         if (th == NULL)
 981                 return -NF_ACCEPT;
 982
 983         if (tcp_error(th, skb, dataoff, state))
 984                 return -NF_ACCEPT;
 985
 986         if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
 987                 return -NF_ACCEPT;
 988
 989         spin_lock_bh(&ct->lock);
 990         old_state = ct->proto.tcp.state;
 991         dir = CTINFO2DIR(ctinfo);
 992         index = get_conntrack_index(th);
 993         new_state = tcp_conntracks[dir][index][old_state];
 994         tuple = &ct->tuplehash[dir].tuple;
 995
 996         switch (new_state) {
 997         case TCP_CONNTRACK_SYN_SENT:
 998                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 999                         break;
1000                 /* RFC 1122: "When a connection is closed actively,
1001                  * it MUST linger in TIME-WAIT state for a time 2xMSL
1002                  * (Maximum Segment Lifetime). However, it MAY accept
1003                  * a new SYN from the remote TCP to reopen the connection
1004                  * directly from TIME-WAIT state, if..."
1005                  * We ignore the conditions because we are in the
1006                  * TIME-WAIT state anyway.
1007                  *
1008                  * Handle aborted connections: we and the server
1009                  * think there is an existing connection but the client
1010                  * aborts it and starts a new one.
1011                  */
1012                 if (((ct->proto.tcp.seen[dir].flags
1013                       | ct->proto.tcp.seen[!dir].flags)
1014                      & IP_CT_TCP_FLAG_CLOSE_INIT)
1015                     || (ct->proto.tcp.last_dir == dir
1016                         && ct->proto.tcp.last_index == TCP_RST_SET)) {
1017                         /* Attempt to reopen a closed/aborted connection.
1018                          * Delete this connection and look up again. */
1019                         spin_unlock_bh(&ct->lock);
1020
1021                         /* Only repeat if we can actually remove the timer.
1022                          * Destruction may already be in progress in process
1023                          * context and we must give it a chance to terminate.
1024                          */
1025                         if (nf_ct_kill(ct))
1026                                 return -NF_REPEAT;
1027                         return NF_DROP;
1028                 }
1029                 fallthrough;
1030         case TCP_CONNTRACK_IGNORE:
1031                 /* Ignored packets:
1032                  *
1033                  * Our connection entry may be out of sync, so ignore
1034                  * packets which may signal the real connection between
1035                  * the client and the server.
1036                  *
1037                  * a) SYN in ORIGINAL
1038                  * b) SYN/ACK in REPLY
1039                  * c) ACK in reply direction after initial SYN in original.
1040                  *
1041                  * If the ignored packet is invalid, the receiver will send
1042                  * a RST we'll catch below.
1043                  */
1044                 if (index == TCP_SYNACK_SET
1045                     && ct->proto.tcp.last_index == TCP_SYN_SET
1046                     && ct->proto.tcp.last_dir != dir
1047                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1048                         /* b) This SYN/ACK acknowledges a SYN that we earlier
1049                          * ignored as invalid. This means that the client and
1050                          * the server are both in sync, while the firewall is
1051                          * not. We get in sync from the previously annotated
1052                          * values.
1053                          */
1054                         old_state = TCP_CONNTRACK_SYN_SENT;
1055                         new_state = TCP_CONNTRACK_SYN_RECV;
1056                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
1057                                 ct->proto.tcp.last_end;
1058                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
1059                                 ct->proto.tcp.last_end;
1060                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
1061                                 ct->proto.tcp.last_win == 0 ?
1062                                         1 : ct->proto.tcp.last_win;
1063                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
1064                                 ct->proto.tcp.last_wscale;
1065                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1066                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
1067                                 ct->proto.tcp.last_flags;
1068                         nf_ct_tcp_state_reset(&ct->proto.tcp.seen[dir]);
1069                         break;
1070                 }
1071                 ct->proto.tcp.last_index = index;
1072                 ct->proto.tcp.last_dir = dir;
1073                 ct->proto.tcp.last_seq = ntohl(th->seq);
1074                 ct->proto.tcp.last_end =
1075                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
1076                 ct->proto.tcp.last_win = ntohs(th->window);
1077
1078                 /* a) This is a SYN in ORIGINAL. The client and the server
1079                  * may be in sync but we are not. In that case, we annotate
1080                  * the TCP options and let the packet go through. If it is a
1081                  * valid SYN packet, the server will reply with a SYN/ACK, and
1082                  * then we'll get in sync. Otherwise, the server potentially
1083                  * responds with a challenge ACK if implementing RFC5961.
1084                  */
1085                 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
1086                         struct ip_ct_tcp_state seen = {};
1087
1088                         ct->proto.tcp.last_flags =
1089                         ct->proto.tcp.last_wscale = 0;
1090                         tcp_options(skb, dataoff, th, &seen);
1091                         if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1092                                 ct->proto.tcp.last_flags |=
1093                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
1094                                 ct->proto.tcp.last_wscale = seen.td_scale;
1095                         }
1096                         if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
1097                                 ct->proto.tcp.last_flags |=
1098                                         IP_CT_TCP_FLAG_SACK_PERM;
1099                         }
1100                         /* Mark the potential for RFC5961 challenge ACK,
1101                          * this pose a special problem for LAST_ACK state
1102                          * as ACK is intrepretated as ACKing last FIN.
1103                          */
1104                         if (old_state == TCP_CONNTRACK_LAST_ACK)
1105                                 ct->proto.tcp.last_flags |=
1106                                         IP_CT_EXP_CHALLENGE_ACK;
1107                 }
1108
1109                 /* possible challenge ack reply to syn */
1110                 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1111                     index == TCP_ACK_SET &&
1112                     dir == IP_CT_DIR_REPLY)
1113                         ct->proto.tcp.last_ack = ntohl(th->ack_seq);
1114
1115                 spin_unlock_bh(&ct->lock);
1116                 nf_ct_l4proto_log_invalid(skb, ct, state,
1117                                           "packet (index %d) in dir %d ignored, state %s",
1118                                           index, dir,
1119                                           tcp_conntrack_names[old_state]);
1120                 return NF_ACCEPT;
1121         case TCP_CONNTRACK_MAX:
1122                 /* Special case for SYN proxy: when the SYN to the server or
1123                  * the SYN/ACK from the server is lost, the client may transmit
1124                  * a keep-alive packet while in SYN_SENT state. This needs to
1125                  * be associated with the original conntrack entry in order to
1126                  * generate a new SYN with the correct sequence number.
1127                  */
1128                 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
1129                     index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
1130                     ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1131                     ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1132                         pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1133                         spin_unlock_bh(&ct->lock);
1134                         return NF_ACCEPT;
1135                 }
1136
1137                 /* Invalid packet */
1138                 spin_unlock_bh(&ct->lock);
1139                 nf_ct_l4proto_log_invalid(skb, ct, state,
1140                                           "packet (index %d) in dir %d invalid, state %s",
1141                                           index, dir,
1142                                           tcp_conntrack_names[old_state]);
1143                 return -NF_ACCEPT;
1144         case TCP_CONNTRACK_TIME_WAIT:
1145                 /* RFC5961 compliance cause stack to send "challenge-ACK"
1146                  * e.g. in response to spurious SYNs.  Conntrack MUST
1147                  * not believe this ACK is acking last FIN.
1148                  */
1149                 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1150                     index == TCP_ACK_SET &&
1151                     ct->proto.tcp.last_dir != dir &&
1152                     ct->proto.tcp.last_index == TCP_SYN_SET &&
1153                     (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1154                         /* Detected RFC5961 challenge ACK */
1155                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1156                         spin_unlock_bh(&ct->lock);
1157                         nf_ct_l4proto_log_invalid(skb, ct, state, "challenge-ack ignored");
1158                         return NF_ACCEPT; /* Don't change state */
1159                 }
1160                 break;
1161         case TCP_CONNTRACK_SYN_SENT2:
1162                 /* tcp_conntracks table is not smart enough to handle
1163                  * simultaneous open.
1164                  */
1165                 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1166                 break;
1167         case TCP_CONNTRACK_SYN_RECV:
1168                 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1169                     ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1170                         new_state = TCP_CONNTRACK_ESTABLISHED;
1171                 break;
1172         case TCP_CONNTRACK_CLOSE:
1173                 if (index != TCP_RST_SET)
1174                         break;
1175
1176                 /* If we are closing, tuple might have been re-used already.
1177                  * last_index, last_ack, and all other ct fields used for
1178                  * sequence/window validation are outdated in that case.
1179                  *
1180                  * As the conntrack can already be expired by GC under pressure,
1181                  * just skip validation checks.
1182                  */
1183                 if (tcp_can_early_drop(ct))
1184                         goto in_window;
1185
1186                 /* td_maxack might be outdated if we let a SYN through earlier */
1187                 if ((ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) &&
1188                     ct->proto.tcp.last_index != TCP_SYN_SET) {
1189                         u32 seq = ntohl(th->seq);
1190
1191                         /* If we are not in established state and SEQ=0 this is most
1192                          * likely an answer to a SYN we let go through above (last_index
1193                          * can be updated due to out-of-order ACKs).
1194                          */
1195                         if (seq == 0 && !nf_conntrack_tcp_established(ct))
1196                                 break;
1197
1198                         if (before(seq, ct->proto.tcp.seen[!dir].td_maxack) &&
1199                             !tn->tcp_ignore_invalid_rst) {
1200                                 /* Invalid RST  */
1201                                 spin_unlock_bh(&ct->lock);
1202                                 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid rst");
1203                                 return -NF_ACCEPT;
1204                         }
1205
1206                         if (!nf_conntrack_tcp_established(ct) ||
1207                             seq == ct->proto.tcp.seen[!dir].td_maxack)
1208                                 break;
1209
1210                         /* Check if rst is part of train, such as
1211                          *   foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1212                          *   foo:80 > bar:4379: R, 235946602:235946602(0)  ack 42
1213                          */
1214                         if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1215                             ct->proto.tcp.last_dir == dir &&
1216                             seq == ct->proto.tcp.last_end)
1217                                 break;
1218
1219                         /* ... RST sequence number doesn't match exactly, keep
1220                          * established state to allow a possible challenge ACK.
1221                          */
1222                         new_state = old_state;
1223                 }
1224                 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1225                          && ct->proto.tcp.last_index == TCP_SYN_SET)
1226                         || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1227                             && ct->proto.tcp.last_index == TCP_ACK_SET))
1228                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1229                         /* RST sent to invalid SYN or ACK we had let through
1230                          * at a) and c) above:
1231                          *
1232                          * a) SYN was in window then
1233                          * c) we hold a half-open connection.
1234                          *
1235                          * Delete our connection entry.
1236                          * We skip window checking, because packet might ACK
1237                          * segments we ignored. */
1238                         goto in_window;
1239                 }
1240
1241                 /* Reset in response to a challenge-ack we let through earlier */
1242                 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1243                     ct->proto.tcp.last_index == TCP_ACK_SET &&
1244                     ct->proto.tcp.last_dir == IP_CT_DIR_REPLY &&
1245                     ntohl(th->seq) == ct->proto.tcp.last_ack)
1246                         goto in_window;
1247
1248                 break;
1249         default:
1250                 /* Keep compilers happy. */
1251                 break;
1252         }
1253
1254         res = tcp_in_window(ct, dir, index,
1255                             skb, dataoff, th, state);
1256         switch (res) {
1257         case NFCT_TCP_IGNORE:
1258                 spin_unlock_bh(&ct->lock);
1259                 return NF_ACCEPT;
1260         case NFCT_TCP_INVALID:
1261                 nf_tcp_handle_invalid(ct, dir, index, skb, state);
1262                 spin_unlock_bh(&ct->lock);
1263                 return -NF_ACCEPT;
1264         case NFCT_TCP_ACCEPT:
1265                 break;
1266         }
1267      in_window:
1268         /* From now on we have got in-window packets */
1269         ct->proto.tcp.last_index = index;
1270         ct->proto.tcp.last_dir = dir;
1271
1272         pr_debug("tcp_conntracks: ");
1273         nf_ct_dump_tuple(tuple);
1274         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1275                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1276                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1277                  old_state, new_state);
1278
1279         ct->proto.tcp.state = new_state;
1280         if (old_state != new_state
1281             && new_state == TCP_CONNTRACK_FIN_WAIT)
1282                 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1283
1284         timeouts = nf_ct_timeout_lookup(ct);
1285         if (!timeouts)
1286                 timeouts = tn->timeouts;
1287
1288         if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1289             timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1290                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1291         else if (unlikely(index == TCP_RST_SET))
1292                 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1293         else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1294                  IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1295                  timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1296                 timeout = timeouts[TCP_CONNTRACK_UNACK];
1297         else if (ct->proto.tcp.last_win == 0 &&
1298                  timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1299                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1300         else
1301                 timeout = timeouts[new_state];
1302         spin_unlock_bh(&ct->lock);
1303
1304         if (new_state != old_state)
1305                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1306
1307         if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1308                 /* If only reply is a RST, we can consider ourselves not to
1309                    have an established connection: this is a fairly common
1310                    problem case, so we can delete the conntrack
1311                    immediately.  --RR */
1312                 if (th->rst) {
1313                         nf_ct_kill_acct(ct, ctinfo, skb);
1314                         return NF_ACCEPT;
1315                 }
1316
1317                 if (index == TCP_SYN_SET && old_state == TCP_CONNTRACK_SYN_SENT) {
1318                         /* do not renew timeout on SYN retransmit.
1319                          *
1320                          * Else port reuse by client or NAT middlebox can keep
1321                          * entry alive indefinitely (including nat info).
1322                          */
1323                         return NF_ACCEPT;
1324                 }
1325
1326                 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1327                  * pickup with loose=1. Avoid large ESTABLISHED timeout.
1328                  */
1329                 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1330                     timeout > timeouts[TCP_CONNTRACK_UNACK])
1331                         timeout = timeouts[TCP_CONNTRACK_UNACK];
1332         } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1333                    && (old_state == TCP_CONNTRACK_SYN_RECV
1334                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1335                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1336                 /* Set ASSURED if we see valid ack in ESTABLISHED
1337                    after SYN_RECV or a valid answer for a picked up
1338                    connection. */
1339                 set_bit(IPS_ASSURED_BIT, &ct->status);
1340                 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1341         }
1342         nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1343
1344         return NF_ACCEPT;
1345 }
1346
1347 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1348
1349 #include <linux/netfilter/nfnetlink.h>
1350 #include <linux/netfilter/nfnetlink_conntrack.h>
1351
1352 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1353                          struct nf_conn *ct, bool destroy)
1354 {
1355         struct nlattr *nest_parms;
1356         struct nf_ct_tcp_flags tmp = {};
1357
1358         spin_lock_bh(&ct->lock);
1359         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1360         if (!nest_parms)
1361                 goto nla_put_failure;
1362
1363         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1364                 goto nla_put_failure;
1365
1366         if (destroy)
1367                 goto skip_state;
1368
1369         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1370                        ct->proto.tcp.seen[0].td_scale) ||
1371             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1372                        ct->proto.tcp.seen[1].td_scale))
1373                 goto nla_put_failure;
1374
1375         tmp.flags = ct->proto.tcp.seen[0].flags;
1376         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1377                     sizeof(struct nf_ct_tcp_flags), &tmp))
1378                 goto nla_put_failure;
1379
1380         tmp.flags = ct->proto.tcp.seen[1].flags;
1381         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1382                     sizeof(struct nf_ct_tcp_flags), &tmp))
1383                 goto nla_put_failure;
1384 skip_state:
1385         spin_unlock_bh(&ct->lock);
1386         nla_nest_end(skb, nest_parms);
1387
1388         return 0;
1389
1390 nla_put_failure:
1391         spin_unlock_bh(&ct->lock);
1392         return -1;
1393 }
1394
1395 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1396         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1397         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1398         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1399         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1400         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len = sizeof(struct nf_ct_tcp_flags) },
1401 };
1402
1403 #define TCP_NLATTR_SIZE ( \
1404         NLA_ALIGN(NLA_HDRLEN + 1) + \
1405         NLA_ALIGN(NLA_HDRLEN + 1) + \
1406         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1407         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1408
1409 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1410 {
1411         struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1412         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1413         int err;
1414
1415         /* updates could not contain anything about the private
1416          * protocol info, in that case skip the parsing */
1417         if (!pattr)
1418                 return 0;
1419
1420         err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1421                                           tcp_nla_policy, NULL);
1422         if (err < 0)
1423                 return err;
1424
1425         if (tb[CTA_PROTOINFO_TCP_STATE] &&
1426             nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1427                 return -EINVAL;
1428
1429         spin_lock_bh(&ct->lock);
1430         if (tb[CTA_PROTOINFO_TCP_STATE])
1431                 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1432
1433         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1434                 struct nf_ct_tcp_flags *attr =
1435                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1436                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1437                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1438         }
1439
1440         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1441                 struct nf_ct_tcp_flags *attr =
1442                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1443                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1444                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1445         }
1446
1447         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1448             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1449             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1450             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1451                 ct->proto.tcp.seen[0].td_scale =
1452                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1453                 ct->proto.tcp.seen[1].td_scale =
1454                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1455         }
1456         spin_unlock_bh(&ct->lock);
1457
1458         return 0;
1459 }
1460
1461 static unsigned int tcp_nlattr_tuple_size(void)
1462 {
1463         static unsigned int size __read_mostly;
1464
1465         if (!size)
1466                 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1467
1468         return size;
1469 }
1470 #endif
1471
1472 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1473
1474 #include <linux/netfilter/nfnetlink.h>
1475 #include <linux/netfilter/nfnetlink_cttimeout.h>
1476
1477 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1478                                      struct net *net, void *data)
1479 {
1480         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1481         unsigned int *timeouts = data;
1482         int i;
1483
1484         if (!timeouts)
1485                 timeouts = tn->timeouts;
1486         /* set default TCP timeouts. */
1487         for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1488                 timeouts[i] = tn->timeouts[i];
1489
1490         if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1491                 timeouts[TCP_CONNTRACK_SYN_SENT] =
1492                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1493         }
1494
1495         if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1496                 timeouts[TCP_CONNTRACK_SYN_RECV] =
1497                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1498         }
1499         if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1500                 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1501                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1502         }
1503         if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1504                 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1505                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1506         }
1507         if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1508                 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1509                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1510         }
1511         if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1512                 timeouts[TCP_CONNTRACK_LAST_ACK] =
1513                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1514         }
1515         if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1516                 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1517                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1518         }
1519         if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1520                 timeouts[TCP_CONNTRACK_CLOSE] =
1521                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1522         }
1523         if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1524                 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1525                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1526         }
1527         if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1528                 timeouts[TCP_CONNTRACK_RETRANS] =
1529                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1530         }
1531         if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1532                 timeouts[TCP_CONNTRACK_UNACK] =
1533                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1534         }
1535
1536         timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1537         return 0;
1538 }
1539
1540 static int
1541 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1542 {
1543         const unsigned int *timeouts = data;
1544
1545         if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1546                         htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1547             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1548                          htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1549             nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1550                          htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1551             nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1552                          htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1553             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1554                          htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1555             nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1556                          htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1557             nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1558                          htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1559             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1560                          htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1561             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1562                          htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1563             nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1564                          htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1565             nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1566                          htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1567                 goto nla_put_failure;
1568         return 0;
1569
1570 nla_put_failure:
1571         return -ENOSPC;
1572 }
1573
1574 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1575         [CTA_TIMEOUT_TCP_SYN_SENT]      = { .type = NLA_U32 },
1576         [CTA_TIMEOUT_TCP_SYN_RECV]      = { .type = NLA_U32 },
1577         [CTA_TIMEOUT_TCP_ESTABLISHED]   = { .type = NLA_U32 },
1578         [CTA_TIMEOUT_TCP_FIN_WAIT]      = { .type = NLA_U32 },
1579         [CTA_TIMEOUT_TCP_CLOSE_WAIT]    = { .type = NLA_U32 },
1580         [CTA_TIMEOUT_TCP_LAST_ACK]      = { .type = NLA_U32 },
1581         [CTA_TIMEOUT_TCP_TIME_WAIT]     = { .type = NLA_U32 },
1582         [CTA_TIMEOUT_TCP_CLOSE]         = { .type = NLA_U32 },
1583         [CTA_TIMEOUT_TCP_SYN_SENT2]     = { .type = NLA_U32 },
1584         [CTA_TIMEOUT_TCP_RETRANS]       = { .type = NLA_U32 },
1585         [CTA_TIMEOUT_TCP_UNACK]         = { .type = NLA_U32 },
1586 };
1587 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1588
1589 void nf_conntrack_tcp_init_net(struct net *net)
1590 {
1591         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1592         int i;
1593
1594         for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1595                 tn->timeouts[i] = tcp_timeouts[i];
1596
1597         /* timeouts[0] is unused, make it same as SYN_SENT so
1598          * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1599          */
1600         tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1601
1602         /* If it is set to zero, we disable picking up already established
1603          * connections.
1604          */
1605         tn->tcp_loose = 1;
1606
1607         /* "Be conservative in what you do,
1608          *  be liberal in what you accept from others."
1609          * If it's non-zero, we mark only out of window RST segments as INVALID.
1610          */
1611         tn->tcp_be_liberal = 0;
1612
1613         /* If it's non-zero, we turn off RST sequence number check */
1614         tn->tcp_ignore_invalid_rst = 0;
1615
1616         /* Max number of the retransmitted packets without receiving an (acceptable)
1617          * ACK from the destination. If this number is reached, a shorter timer
1618          * will be started.
1619          */
1620         tn->tcp_max_retrans = 3;
1621
1622 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
1623         tn->offload_timeout = 30 * HZ;
1624 #endif
1625 }
1626
1627 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1628 {
1629         .l4proto                = IPPROTO_TCP,
1630 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1631         .print_conntrack        = tcp_print_conntrack,
1632 #endif
1633         .can_early_drop         = tcp_can_early_drop,
1634 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1635         .to_nlattr              = tcp_to_nlattr,
1636         .from_nlattr            = nlattr_to_tcp,
1637         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1638         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1639         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1640         .nlattr_size            = TCP_NLATTR_SIZE,
1641         .nla_policy             = nf_ct_port_nla_policy,
1642 #endif
1643 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1644         .ctnl_timeout           = {
1645                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1646                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1647                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1648                 .obj_size       = sizeof(unsigned int) *
1649                                         TCP_CONNTRACK_TIMEOUT_MAX,
1650                 .nla_policy     = tcp_timeout_nla_policy,
1651         },
1652 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1653 };