net/netfilter/nf_conntrack_proto_tcp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* (C) 1999-2001 Paul `Rusty' Russell
   3  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   4  * (C) 2002-2013 Jozsef Kadlecsik <kadlec@netfilter.org>
   5  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   6  */
   7
   8 #include <linux/types.h>
   9 #include <linux/timer.h>
  10 #include <linux/module.h>
  11 #include <linux/in.h>
  12 #include <linux/tcp.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/ipv6.h>
  16 #include <net/ip6_checksum.h>
  17 #include <asm/unaligned.h>
  18
  19 #include <net/tcp.h>
  20
  21 #include <linux/netfilter.h>
  22 #include <linux/netfilter_ipv4.h>
  23 #include <linux/netfilter_ipv6.h>
  24 #include <net/netfilter/nf_conntrack.h>
  25 #include <net/netfilter/nf_conntrack_l4proto.h>
  26 #include <net/netfilter/nf_conntrack_ecache.h>
  27 #include <net/netfilter/nf_conntrack_seqadj.h>
  28 #include <net/netfilter/nf_conntrack_synproxy.h>
  29 #include <net/netfilter/nf_conntrack_timeout.h>
  30 #include <net/netfilter/nf_log.h>
  31 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  32 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  33
  34   /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
  35      closely.  They're more complex. --RR */
  36
  37 static const char *const tcp_conntrack_names[] = {
  38         "NONE",
  39         "SYN_SENT",
  40         "SYN_RECV",
  41         "ESTABLISHED",
  42         "FIN_WAIT",
  43         "CLOSE_WAIT",
  44         "LAST_ACK",
  45         "TIME_WAIT",
  46         "CLOSE",
  47         "SYN_SENT2",
  48 };
  49
  50 enum nf_ct_tcp_action {
  51         NFCT_TCP_IGNORE,
  52         NFCT_TCP_INVALID,
  53         NFCT_TCP_ACCEPT,
  54 };
  55
  56 #define SECS * HZ
  57 #define MINS * 60 SECS
  58 #define HOURS * 60 MINS
  59 #define DAYS * 24 HOURS
  60
  61 static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
  62         [TCP_CONNTRACK_SYN_SENT]        = 2 MINS,
  63         [TCP_CONNTRACK_SYN_RECV]        = 60 SECS,
  64         [TCP_CONNTRACK_ESTABLISHED]     = 5 DAYS,
  65         [TCP_CONNTRACK_FIN_WAIT]        = 2 MINS,
  66         [TCP_CONNTRACK_CLOSE_WAIT]      = 60 SECS,
  67         [TCP_CONNTRACK_LAST_ACK]        = 30 SECS,
  68         [TCP_CONNTRACK_TIME_WAIT]       = 2 MINS,
  69         [TCP_CONNTRACK_CLOSE]           = 10 SECS,
  70         [TCP_CONNTRACK_SYN_SENT2]       = 2 MINS,
  71 /* RFC1122 says the R2 limit should be at least 100 seconds.
  72    Linux uses 15 packets as limit, which corresponds
  73    to ~13-30min depending on RTO. */
  74         [TCP_CONNTRACK_RETRANS]         = 5 MINS,
  75         [TCP_CONNTRACK_UNACK]           = 5 MINS,
  76 };
  77
  78 #define sNO TCP_CONNTRACK_NONE
  79 #define sSS TCP_CONNTRACK_SYN_SENT
  80 #define sSR TCP_CONNTRACK_SYN_RECV
  81 #define sES TCP_CONNTRACK_ESTABLISHED
  82 #define sFW TCP_CONNTRACK_FIN_WAIT
  83 #define sCW TCP_CONNTRACK_CLOSE_WAIT
  84 #define sLA TCP_CONNTRACK_LAST_ACK
  85 #define sTW TCP_CONNTRACK_TIME_WAIT
  86 #define sCL TCP_CONNTRACK_CLOSE
  87 #define sS2 TCP_CONNTRACK_SYN_SENT2
  88 #define sIV TCP_CONNTRACK_MAX
  89 #define sIG TCP_CONNTRACK_IGNORE
  90
  91 /* What TCP flags are set from RST/SYN/FIN/ACK. */
  92 enum tcp_bit_set {
  93         TCP_SYN_SET,
  94         TCP_SYNACK_SET,
  95         TCP_FIN_SET,
  96         TCP_ACK_SET,
  97         TCP_RST_SET,
  98         TCP_NONE_SET,
  99 };
 100
 101 /*
 102  * The TCP state transition table needs a few words...
 103  *
 104  * We are the man in the middle. All the packets go through us
 105  * but might get lost in transit to the destination.
 106  * It is assumed that the destinations can't receive segments
 107  * we haven't seen.
 108  *
 109  * The checked segment is in window, but our windows are *not*
 110  * equivalent with the ones of the sender/receiver. We always
 111  * try to guess the state of the current sender.
 112  *
 113  * The meaning of the states are:
 114  *
 115  * NONE:        initial state
 116  * SYN_SENT:    SYN-only packet seen
 117  * SYN_SENT2:   SYN-only packet seen from reply dir, simultaneous open
 118  * SYN_RECV:    SYN-ACK packet seen
 119  * ESTABLISHED: ACK packet seen
 120  * FIN_WAIT:    FIN packet seen
 121  * CLOSE_WAIT:  ACK seen (after FIN)
 122  * LAST_ACK:    FIN seen (after FIN)
 123  * TIME_WAIT:   last ACK seen
 124  * CLOSE:       closed connection (RST)
 125  *
 126  * Packets marked as IGNORED (sIG):
 127  *      if they may be either invalid or valid
 128  *      and the receiver may send back a connection
 129  *      closing RST or a SYN/ACK.
 130  *
 131  * Packets marked as INVALID (sIV):
 132  *      if we regard them as truly invalid packets
 133  */
 134 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
 135         {
 136 /* ORIGINAL */
 137 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 138 /*syn*/    { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
 139 /*
 140  *      sNO -> sSS      Initialize a new connection
 141  *      sSS -> sSS      Retransmitted SYN
 142  *      sS2 -> sS2      Late retransmitted SYN
 143  *      sSR -> sIG
 144  *      sES -> sIG      Error: SYNs in window outside the SYN_SENT state
 145  *                      are errors. Receiver will reply with RST
 146  *                      and close the connection.
 147  *                      Or we are not in sync and hold a dead connection.
 148  *      sFW -> sIG
 149  *      sCW -> sIG
 150  *      sLA -> sIG
 151  *      sTW -> sSS      Reopened connection (RFC 1122).
 152  *      sCL -> sSS
 153  */
 154 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 155 /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
 156 /*
 157  *      sNO -> sIV      Too late and no reason to do anything
 158  *      sSS -> sIV      Client can't send SYN and then SYN/ACK
 159  *      sS2 -> sSR      SYN/ACK sent to SYN2 in simultaneous open
 160  *      sSR -> sSR      Late retransmitted SYN/ACK in simultaneous open
 161  *      sES -> sIV      Invalid SYN/ACK packets sent by the client
 162  *      sFW -> sIV
 163  *      sCW -> sIV
 164  *      sLA -> sIV
 165  *      sTW -> sIV
 166  *      sCL -> sIV
 167  */
 168 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 169 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 170 /*
 171  *      sNO -> sIV      Too late and no reason to do anything...
 172  *      sSS -> sIV      Client migth not send FIN in this state:
 173  *                      we enforce waiting for a SYN/ACK reply first.
 174  *      sS2 -> sIV
 175  *      sSR -> sFW      Close started.
 176  *      sES -> sFW
 177  *      sFW -> sLA      FIN seen in both directions, waiting for
 178  *                      the last ACK.
 179  *                      Migth be a retransmitted FIN as well...
 180  *      sCW -> sLA
 181  *      sLA -> sLA      Retransmitted FIN. Remain in the same state.
 182  *      sTW -> sTW
 183  *      sCL -> sCL
 184  */
 185 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 186 /*ack*/    { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 187 /*
 188  *      sNO -> sES      Assumed.
 189  *      sSS -> sIV      ACK is invalid: we haven't seen a SYN/ACK yet.
 190  *      sS2 -> sIV
 191  *      sSR -> sES      Established state is reached.
 192  *      sES -> sES      :-)
 193  *      sFW -> sCW      Normal close request answered by ACK.
 194  *      sCW -> sCW
 195  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 196  *      sTW -> sTW      Retransmitted last ACK. Remain in the same state.
 197  *      sCL -> sCL
 198  */
 199 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 200 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 201 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 202         },
 203         {
 204 /* REPLY */
 205 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 206 /*syn*/    { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
 207 /*
 208  *      sNO -> sIV      Never reached.
 209  *      sSS -> sS2      Simultaneous open
 210  *      sS2 -> sS2      Retransmitted simultaneous SYN
 211  *      sSR -> sIV      Invalid SYN packets sent by the server
 212  *      sES -> sIV
 213  *      sFW -> sIV
 214  *      sCW -> sIV
 215  *      sLA -> sIV
 216  *      sTW -> sSS      Reopened connection, but server may have switched role
 217  *      sCL -> sIV
 218  */
 219 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 220 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
 221 /*
 222  *      sSS -> sSR      Standard open.
 223  *      sS2 -> sSR      Simultaneous open
 224  *      sSR -> sIG      Retransmitted SYN/ACK, ignore it.
 225  *      sES -> sIG      Late retransmitted SYN/ACK?
 226  *      sFW -> sIG      Might be SYN/ACK answering ignored SYN
 227  *      sCW -> sIG
 228  *      sLA -> sIG
 229  *      sTW -> sIG
 230  *      sCL -> sIG
 231  */
 232 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 233 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 234 /*
 235  *      sSS -> sIV      Server might not send FIN in this state.
 236  *      sS2 -> sIV
 237  *      sSR -> sFW      Close started.
 238  *      sES -> sFW
 239  *      sFW -> sLA      FIN seen in both directions.
 240  *      sCW -> sLA
 241  *      sLA -> sLA      Retransmitted FIN.
 242  *      sTW -> sTW
 243  *      sCL -> sCL
 244  */
 245 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 246 /*ack*/    { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
 247 /*
 248  *      sSS -> sIG      Might be a half-open connection.
 249  *      sS2 -> sIG
 250  *      sSR -> sSR      Might answer late resent SYN.
 251  *      sES -> sES      :-)
 252  *      sFW -> sCW      Normal close request answered by ACK.
 253  *      sCW -> sCW
 254  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 255  *      sTW -> sTW      Retransmitted last ACK.
 256  *      sCL -> sCL
 257  */
 258 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 259 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 260 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 261         }
 262 };
 263
 264 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 265 /* Print out the private part of the conntrack. */
 266 static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 267 {
 268         if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
 269                 return;
 270
 271         seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
 272 }
 273 #endif
 274
 275 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
 276 {
 277         if (tcph->rst) return TCP_RST_SET;
 278         else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
 279         else if (tcph->fin) return TCP_FIN_SET;
 280         else if (tcph->ack) return TCP_ACK_SET;
 281         else return TCP_NONE_SET;
 282 }
 283
 284 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
 285    in IP Filter' by Guido van Rooij.
 286
 287    http://www.sane.nl/events/sane2000/papers.html
 288    http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
 289
 290    The boundaries and the conditions are changed according to RFC793:
 291    the packet must intersect the window (i.e. segments may be
 292    after the right or before the left edge) and thus receivers may ACK
 293    segments after the right edge of the window.
 294
 295         td_maxend = max(sack + max(win,1)) seen in reply packets
 296         td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
 297         td_maxwin += seq + len - sender.td_maxend
 298                         if seq + len > sender.td_maxend
 299         td_end    = max(seq + len) seen in sent packets
 300
 301    I.   Upper bound for valid data:     seq <= sender.td_maxend
 302    II.  Lower bound for valid data:     seq + len >= sender.td_end - receiver.td_maxwin
 303    III. Upper bound for valid (s)ack:   sack <= receiver.td_end
 304    IV.  Lower bound for valid (s)ack:   sack >= receiver.td_end - MAXACKWINDOW
 305
 306    where sack is the highest right edge of sack block found in the packet
 307    or ack in the case of packet without SACK option.
 308
 309    The upper bound limit for a valid (s)ack is not ignored -
 310    we doesn't have to deal with fragments.
 311 */
 312
 313 static inline __u32 segment_seq_plus_len(__u32 seq,
 314                                          size_t len,
 315                                          unsigned int dataoff,
 316                                          const struct tcphdr *tcph)
 317 {
 318         /* XXX Should I use payload length field in IP/IPv6 header ?
 319          * - YK */
 320         return (seq + len - dataoff - tcph->doff*4
 321                 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
 322 }
 323
 324 /* Fixme: what about big packets? */
 325 #define MAXACKWINCONST                  66000
 326 #define MAXACKWINDOW(sender)                                            \
 327         ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin     \
 328                                               : MAXACKWINCONST)
 329
 330 /*
 331  * Simplified tcp_parse_options routine from tcp_input.c
 332  */
 333 static void tcp_options(const struct sk_buff *skb,
 334                         unsigned int dataoff,
 335                         const struct tcphdr *tcph,
 336                         struct ip_ct_tcp_state *state)
 337 {
 338         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 339         const unsigned char *ptr;
 340         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 341
 342         if (!length)
 343                 return;
 344
 345         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 346                                  length, buff);
 347         if (!ptr)
 348                 return;
 349
 350         state->td_scale = 0;
 351         state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
 352
 353         while (length > 0) {
 354                 int opcode=*ptr++;
 355                 int opsize;
 356
 357                 switch (opcode) {
 358                 case TCPOPT_EOL:
 359                         return;
 360                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 361                         length--;
 362                         continue;
 363                 default:
 364                         if (length < 2)
 365                                 return;
 366                         opsize=*ptr++;
 367                         if (opsize < 2) /* "silly options" */
 368                                 return;
 369                         if (opsize > length)
 370                                 return; /* don't parse partial options */
 371
 372                         if (opcode == TCPOPT_SACK_PERM
 373                             && opsize == TCPOLEN_SACK_PERM)
 374                                 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
 375                         else if (opcode == TCPOPT_WINDOW
 376                                  && opsize == TCPOLEN_WINDOW) {
 377                                 state->td_scale = *(u_int8_t *)ptr;
 378
 379                                 if (state->td_scale > TCP_MAX_WSCALE)
 380                                         state->td_scale = TCP_MAX_WSCALE;
 381
 382                                 state->flags |=
 383                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 384                         }
 385                         ptr += opsize - 2;
 386                         length -= opsize;
 387                 }
 388         }
 389 }
 390
 391 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
 392                      const struct tcphdr *tcph, __u32 *sack)
 393 {
 394         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 395         const unsigned char *ptr;
 396         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 397         __u32 tmp;
 398
 399         if (!length)
 400                 return;
 401
 402         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 403                                  length, buff);
 404         if (!ptr)
 405                 return;
 406
 407         /* Fast path for timestamp-only option */
 408         if (length == TCPOLEN_TSTAMP_ALIGNED
 409             && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
 410                                        | (TCPOPT_NOP << 16)
 411                                        | (TCPOPT_TIMESTAMP << 8)
 412                                        | TCPOLEN_TIMESTAMP))
 413                 return;
 414
 415         while (length > 0) {
 416                 int opcode = *ptr++;
 417                 int opsize, i;
 418
 419                 switch (opcode) {
 420                 case TCPOPT_EOL:
 421                         return;
 422                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 423                         length--;
 424                         continue;
 425                 default:
 426                         if (length < 2)
 427                                 return;
 428                         opsize = *ptr++;
 429                         if (opsize < 2) /* "silly options" */
 430                                 return;
 431                         if (opsize > length)
 432                                 return; /* don't parse partial options */
 433
 434                         if (opcode == TCPOPT_SACK
 435                             && opsize >= (TCPOLEN_SACK_BASE
 436                                           + TCPOLEN_SACK_PERBLOCK)
 437                             && !((opsize - TCPOLEN_SACK_BASE)
 438                                  % TCPOLEN_SACK_PERBLOCK)) {
 439                                 for (i = 0;
 440                                      i < (opsize - TCPOLEN_SACK_BASE);
 441                                      i += TCPOLEN_SACK_PERBLOCK) {
 442                                         tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
 443
 444                                         if (after(tmp, *sack))
 445                                                 *sack = tmp;
 446                                 }
 447                                 return;
 448                         }
 449                         ptr += opsize - 2;
 450                         length -= opsize;
 451                 }
 452         }
 453 }
 454
 455 static void tcp_init_sender(struct ip_ct_tcp_state *sender,
 456                             struct ip_ct_tcp_state *receiver,
 457                             const struct sk_buff *skb,
 458                             unsigned int dataoff,
 459                             const struct tcphdr *tcph,
 460                             u32 end, u32 win)
 461 {
 462         /* SYN-ACK in reply to a SYN
 463          * or SYN from reply direction in simultaneous open.
 464          */
 465         sender->td_end =
 466         sender->td_maxend = end;
 467         sender->td_maxwin = (win == 0 ? 1 : win);
 468
 469         tcp_options(skb, dataoff, tcph, sender);
 470         /* RFC 1323:
 471          * Both sides must send the Window Scale option
 472          * to enable window scaling in either direction.
 473          */
 474         if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
 475               receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) {
 476                 sender->td_scale = 0;
 477                 receiver->td_scale = 0;
 478         }
 479 }
 480
 481 __printf(6, 7)
 482 static enum nf_ct_tcp_action nf_tcp_log_invalid(const struct sk_buff *skb,
 483                                                 const struct nf_conn *ct,
 484                                                 const struct nf_hook_state *state,
 485                                                 const struct ip_ct_tcp_state *sender,
 486                                                 enum nf_ct_tcp_action ret,
 487                                                 const char *fmt, ...)
 488 {
 489         const struct nf_tcp_net *tn = nf_tcp_pernet(nf_ct_net(ct));
 490         struct va_format vaf;
 491         va_list args;
 492         bool be_liberal;
 493
 494         be_liberal = sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || tn->tcp_be_liberal;
 495         if (be_liberal)
 496                 return NFCT_TCP_ACCEPT;
 497
 498         va_start(args, fmt);
 499         vaf.fmt = fmt;
 500         vaf.va = &args;
 501         nf_ct_l4proto_log_invalid(skb, ct, state, "%pV", &vaf);
 502         va_end(args);
 503
 504         return ret;
 505 }
 506
 507 static enum nf_ct_tcp_action
 508 tcp_in_window(struct nf_conn *ct, enum ip_conntrack_dir dir,
 509               unsigned int index, const struct sk_buff *skb,
 510               unsigned int dataoff, const struct tcphdr *tcph,
 511               const struct nf_hook_state *hook_state)
 512 {
 513         struct ip_ct_tcp *state = &ct->proto.tcp;
 514         struct ip_ct_tcp_state *sender = &state->seen[dir];
 515         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 516         __u32 seq, ack, sack, end, win, swin;
 517         bool in_recv_win, seq_ok;
 518         s32 receiver_offset;
 519         u16 win_raw;
 520
 521         /*
 522          * Get the required data from the packet.
 523          */
 524         seq = ntohl(tcph->seq);
 525         ack = sack = ntohl(tcph->ack_seq);
 526         win_raw = ntohs(tcph->window);
 527         win = win_raw;
 528         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
 529
 530         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
 531                 tcp_sack(skb, dataoff, tcph, &sack);
 532
 533         /* Take into account NAT sequence number mangling */
 534         receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
 535         ack -= receiver_offset;
 536         sack -= receiver_offset;
 537
 538         if (sender->td_maxwin == 0) {
 539                 /*
 540                  * Initialize sender data.
 541                  */
 542                 if (tcph->syn) {
 543                         tcp_init_sender(sender, receiver,
 544                                         skb, dataoff, tcph,
 545                                         end, win);
 546                         if (!tcph->ack)
 547                                 /* Simultaneous open */
 548                                 return NFCT_TCP_ACCEPT;
 549                 } else {
 550                         /*
 551                          * We are in the middle of a connection,
 552                          * its history is lost for us.
 553                          * Let's try to use the data from the packet.
 554                          */
 555                         sender->td_end = end;
 556                         swin = win << sender->td_scale;
 557                         sender->td_maxwin = (swin == 0 ? 1 : swin);
 558                         sender->td_maxend = end + sender->td_maxwin;
 559                         if (receiver->td_maxwin == 0) {
 560                                 /* We haven't seen traffic in the other
 561                                  * direction yet but we have to tweak window
 562                                  * tracking to pass III and IV until that
 563                                  * happens.
 564                                  */
 565                                 receiver->td_end = receiver->td_maxend = sack;
 566                         } else if (sack == receiver->td_end + 1) {
 567                                 /* Likely a reply to a keepalive.
 568                                  * Needed for III.
 569                                  */
 570                                 receiver->td_end++;
 571                         }
 572
 573                 }
 574         } else if (tcph->syn &&
 575                    after(end, sender->td_end) &&
 576                    (state->state == TCP_CONNTRACK_SYN_SENT ||
 577                     state->state == TCP_CONNTRACK_SYN_RECV)) {
 578                 /*
 579                  * RFC 793: "if a TCP is reinitialized ... then it need
 580                  * not wait at all; it must only be sure to use sequence
 581                  * numbers larger than those recently used."
 582                  *
 583                  * Re-init state for this direction, just like for the first
 584                  * syn(-ack) reply, it might differ in seq, ack or tcp options.
 585                  */
 586                 tcp_init_sender(sender, receiver,
 587                                 skb, dataoff, tcph,
 588                                 end, win);
 589
 590                 if (dir == IP_CT_DIR_REPLY && !tcph->ack)
 591                         return NFCT_TCP_ACCEPT;
 592         }
 593
 594         if (!(tcph->ack)) {
 595                 /*
 596                  * If there is no ACK, just pretend it was set and OK.
 597                  */
 598                 ack = sack = receiver->td_end;
 599         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
 600                     (TCP_FLAG_ACK|TCP_FLAG_RST))
 601                    && (ack == 0)) {
 602                 /*
 603                  * Broken TCP stacks, that set ACK in RST packets as well
 604                  * with zero ack value.
 605                  */
 606                 ack = sack = receiver->td_end;
 607         }
 608
 609         if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
 610                 /*
 611                  * RST sent answering SYN.
 612                  */
 613                 seq = end = sender->td_end;
 614
 615         seq_ok = before(seq, sender->td_maxend + 1);
 616         if (!seq_ok) {
 617                 u32 overshot = end - sender->td_maxend + 1;
 618                 bool ack_ok;
 619
 620                 ack_ok = after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1);
 621                 in_recv_win = receiver->td_maxwin &&
 622                               after(end, sender->td_end - receiver->td_maxwin - 1);
 623
 624                 if (in_recv_win &&
 625                     ack_ok &&
 626                     overshot <= receiver->td_maxwin &&
 627                     before(sack, receiver->td_end + 1)) {
 628                         /* Work around TCPs that send more bytes than allowed by
 629                          * the receive window.
 630                          *
 631                          * If the (marked as invalid) packet is allowed to pass by
 632                          * the ruleset and the peer acks this data, then its possible
 633                          * all future packets will trigger 'ACK is over upper bound' check.
 634                          *
 635                          * Thus if only the sequence check fails then do update td_end so
 636                          * possible ACK for this data can update internal state.
 637                          */
 638                         sender->td_end = end;
 639                         sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 640
 641                         return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 642                                                   "%u bytes more than expected", overshot);
 643                 }
 644
 645                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
 646                                           "SEQ is over upper bound %u (over the window of the receiver)",
 647                                           sender->td_maxend + 1);
 648         }
 649
 650         if (!before(sack, receiver->td_end + 1))
 651                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
 652                                           "ACK is over upper bound %u (ACKed data not seen yet)",
 653                                           receiver->td_end + 1);
 654
 655         /* Is the ending sequence in the receive window (if available)? */
 656         in_recv_win = !receiver->td_maxwin ||
 657                       after(end, sender->td_end - receiver->td_maxwin - 1);
 658         if (!in_recv_win)
 659                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 660                                           "SEQ is under lower bound %u (already ACKed data retransmitted)",
 661                                           sender->td_end - receiver->td_maxwin - 1);
 662         if (!after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1))
 663                 return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
 664                                           "ignored ACK under lower bound %u (possible overly delayed)",
 665                                           receiver->td_end - MAXACKWINDOW(sender) - 1);
 666
 667         /* Take into account window scaling (RFC 1323). */
 668         if (!tcph->syn)
 669                 win <<= sender->td_scale;
 670
 671         /* Update sender data. */
 672         swin = win + (sack - ack);
 673         if (sender->td_maxwin < swin)
 674                 sender->td_maxwin = swin;
 675         if (after(end, sender->td_end)) {
 676                 sender->td_end = end;
 677                 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 678         }
 679         if (tcph->ack) {
 680                 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
 681                         sender->td_maxack = ack;
 682                         sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
 683                 } else if (after(ack, sender->td_maxack)) {
 684                         sender->td_maxack = ack;
 685                 }
 686         }
 687
 688         /* Update receiver data. */
 689         if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
 690                 receiver->td_maxwin += end - sender->td_maxend;
 691         if (after(sack + win, receiver->td_maxend - 1)) {
 692                 receiver->td_maxend = sack + win;
 693                 if (win == 0)
 694                         receiver->td_maxend++;
 695         }
 696         if (ack == receiver->td_end)
 697                 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 698
 699         /* Check retransmissions. */
 700         if (index == TCP_ACK_SET) {
 701                 if (state->last_dir == dir &&
 702                     state->last_seq == seq &&
 703                     state->last_ack == ack &&
 704                     state->last_end == end &&
 705                     state->last_win == win_raw) {
 706                         state->retrans++;
 707                 } else {
 708                         state->last_dir = dir;
 709                         state->last_seq = seq;
 710                         state->last_ack = ack;
 711                         state->last_end = end;
 712                         state->last_win = win_raw;
 713                         state->retrans = 0;
 714                 }
 715         }
 716
 717         return NFCT_TCP_ACCEPT;
 718 }
 719
 720 static void __cold nf_tcp_handle_invalid(struct nf_conn *ct,
 721                                          enum ip_conntrack_dir dir,
 722                                          int index,
 723                                          const struct sk_buff *skb,
 724                                          const struct nf_hook_state *hook_state)
 725 {
 726         const unsigned int *timeouts;
 727         const struct nf_tcp_net *tn;
 728         unsigned int timeout;
 729         u32 expires;
 730
 731         if (!test_bit(IPS_ASSURED_BIT, &ct->status) ||
 732             test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
 733                 return;
 734
 735         /* We don't want to have connections hanging around in ESTABLISHED
 736          * state for long time 'just because' conntrack deemed a FIN/RST
 737          * out-of-window.
 738          *
 739          * Shrink the timeout just like when there is unacked data.
 740          * This speeds up eviction of 'dead' connections where the
 741          * connection and conntracks internal state are out of sync.
 742          */
 743         switch (index) {
 744         case TCP_RST_SET:
 745         case TCP_FIN_SET:
 746                 break;
 747         default:
 748                 return;
 749         }
 750
 751         if (ct->proto.tcp.last_dir != dir &&
 752             (ct->proto.tcp.last_index == TCP_FIN_SET ||
 753              ct->proto.tcp.last_index == TCP_RST_SET)) {
 754                 expires = nf_ct_expires(ct);
 755                 if (expires < 120 * HZ)
 756                         return;
 757
 758                 tn = nf_tcp_pernet(nf_ct_net(ct));
 759                 timeouts = nf_ct_timeout_lookup(ct);
 760                 if (!timeouts)
 761                         timeouts = tn->timeouts;
 762
 763                 timeout = READ_ONCE(timeouts[TCP_CONNTRACK_UNACK]);
 764                 if (expires > timeout) {
 765                         nf_ct_l4proto_log_invalid(skb, ct, hook_state,
 766                                           "packet (index %d, dir %d) response for index %d lower timeout to %u",
 767                                           index, dir, ct->proto.tcp.last_index, timeout);
 768
 769                         WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp);
 770                 }
 771         } else {
 772                 ct->proto.tcp.last_index = index;
 773                 ct->proto.tcp.last_dir = dir;
 774         }
 775 }
 776
 777 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
 778 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
 779                                  TCPHDR_URG) + 1] =
 780 {
 781         [TCPHDR_SYN]                            = 1,
 782         [TCPHDR_SYN|TCPHDR_URG]                 = 1,
 783         [TCPHDR_SYN|TCPHDR_ACK]                 = 1,
 784         [TCPHDR_RST]                            = 1,
 785         [TCPHDR_RST|TCPHDR_ACK]                 = 1,
 786         [TCPHDR_FIN|TCPHDR_ACK]                 = 1,
 787         [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG]      = 1,
 788         [TCPHDR_ACK]                            = 1,
 789         [TCPHDR_ACK|TCPHDR_URG]                 = 1,
 790 };
 791
 792 static void tcp_error_log(const struct sk_buff *skb,
 793                           const struct nf_hook_state *state,
 794                           const char *msg)
 795 {
 796         nf_l4proto_log_invalid(skb, state, IPPROTO_TCP, "%s", msg);
 797 }
 798
 799 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
 800 static bool tcp_error(const struct tcphdr *th,
 801                       struct sk_buff *skb,
 802                       unsigned int dataoff,
 803                       const struct nf_hook_state *state)
 804 {
 805         unsigned int tcplen = skb->len - dataoff;
 806         u8 tcpflags;
 807
 808         /* Not whole TCP header or malformed packet */
 809         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
 810                 tcp_error_log(skb, state, "truncated packet");
 811                 return true;
 812         }
 813
 814         /* Checksum invalid? Ignore.
 815          * We skip checking packets on the outgoing path
 816          * because the checksum is assumed to be correct.
 817          */
 818         /* FIXME: Source route IP option packets --RR */
 819         if (state->net->ct.sysctl_checksum &&
 820             state->hook == NF_INET_PRE_ROUTING &&
 821             nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
 822                 tcp_error_log(skb, state, "bad checksum");
 823                 return true;
 824         }
 825
 826         /* Check TCP flags. */
 827         tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
 828         if (!tcp_valid_flags[tcpflags]) {
 829                 tcp_error_log(skb, state, "invalid tcp flag combination");
 830                 return true;
 831         }
 832
 833         return false;
 834 }
 835
 836 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
 837                              unsigned int dataoff,
 838                              const struct tcphdr *th)
 839 {
 840         enum tcp_conntrack new_state;
 841         struct net *net = nf_ct_net(ct);
 842         const struct nf_tcp_net *tn = nf_tcp_pernet(net);
 843
 844         /* Don't need lock here: this conntrack not in circulation yet */
 845         new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
 846
 847         /* Invalid: delete conntrack */
 848         if (new_state >= TCP_CONNTRACK_MAX) {
 849                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
 850                 return false;
 851         }
 852
 853         if (new_state == TCP_CONNTRACK_SYN_SENT) {
 854                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 855                 /* SYN packet */
 856                 ct->proto.tcp.seen[0].td_end =
 857                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 858                                              dataoff, th);
 859                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 860                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 861                         ct->proto.tcp.seen[0].td_maxwin = 1;
 862                 ct->proto.tcp.seen[0].td_maxend =
 863                         ct->proto.tcp.seen[0].td_end;
 864
 865                 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
 866         } else if (tn->tcp_loose == 0) {
 867                 /* Don't try to pick up connections. */
 868                 return false;
 869         } else {
 870                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
 871                 /*
 872                  * We are in the middle of a connection,
 873                  * its history is lost for us.
 874                  * Let's try to use the data from the packet.
 875                  */
 876                 ct->proto.tcp.seen[0].td_end =
 877                         segment_seq_plus_len(ntohl(th->seq), skb->len,
 878                                              dataoff, th);
 879                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
 880                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
 881                         ct->proto.tcp.seen[0].td_maxwin = 1;
 882                 ct->proto.tcp.seen[0].td_maxend =
 883                         ct->proto.tcp.seen[0].td_end +
 884                         ct->proto.tcp.seen[0].td_maxwin;
 885
 886                 /* We assume SACK and liberal window checking to handle
 887                  * window scaling */
 888                 ct->proto.tcp.seen[0].flags =
 889                 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
 890                                               IP_CT_TCP_FLAG_BE_LIBERAL;
 891         }
 892
 893         /* tcp_packet will set them */
 894         ct->proto.tcp.last_index = TCP_NONE_SET;
 895         return true;
 896 }
 897
 898 static bool tcp_can_early_drop(const struct nf_conn *ct)
 899 {
 900         switch (ct->proto.tcp.state) {
 901         case TCP_CONNTRACK_FIN_WAIT:
 902         case TCP_CONNTRACK_LAST_ACK:
 903         case TCP_CONNTRACK_TIME_WAIT:
 904         case TCP_CONNTRACK_CLOSE:
 905         case TCP_CONNTRACK_CLOSE_WAIT:
 906                 return true;
 907         default:
 908                 break;
 909         }
 910
 911         return false;
 912 }
 913
 914 static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state)
 915 {
 916         state->td_end           = 0;
 917         state->td_maxend        = 0;
 918         state->td_maxwin        = 0;
 919         state->td_maxack        = 0;
 920         state->td_scale         = 0;
 921         state->flags            &= IP_CT_TCP_FLAG_BE_LIBERAL;
 922 }
 923
 924 /* Returns verdict for packet, or -1 for invalid. */
 925 int nf_conntrack_tcp_packet(struct nf_conn *ct,
 926                             struct sk_buff *skb,
 927                             unsigned int dataoff,
 928                             enum ip_conntrack_info ctinfo,
 929                             const struct nf_hook_state *state)
 930 {
 931         struct net *net = nf_ct_net(ct);
 932         struct nf_tcp_net *tn = nf_tcp_pernet(net);
 933         struct nf_conntrack_tuple *tuple;
 934         enum tcp_conntrack new_state, old_state;
 935         unsigned int index, *timeouts;
 936         enum nf_ct_tcp_action res;
 937         enum ip_conntrack_dir dir;
 938         const struct tcphdr *th;
 939         struct tcphdr _tcph;
 940         unsigned long timeout;
 941
 942         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 943         if (th == NULL)
 944                 return -NF_ACCEPT;
 945
 946         if (tcp_error(th, skb, dataoff, state))
 947                 return -NF_ACCEPT;
 948
 949         if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
 950                 return -NF_ACCEPT;
 951
 952         spin_lock_bh(&ct->lock);
 953         old_state = ct->proto.tcp.state;
 954         dir = CTINFO2DIR(ctinfo);
 955         index = get_conntrack_index(th);
 956         new_state = tcp_conntracks[dir][index][old_state];
 957         tuple = &ct->tuplehash[dir].tuple;
 958
 959         switch (new_state) {
 960         case TCP_CONNTRACK_SYN_SENT:
 961                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 962                         break;
 963                 /* RFC 1122: "When a connection is closed actively,
 964                  * it MUST linger in TIME-WAIT state for a time 2xMSL
 965                  * (Maximum Segment Lifetime). However, it MAY accept
 966                  * a new SYN from the remote TCP to reopen the connection
 967                  * directly from TIME-WAIT state, if..."
 968                  * We ignore the conditions because we are in the
 969                  * TIME-WAIT state anyway.
 970                  *
 971                  * Handle aborted connections: we and the server
 972                  * think there is an existing connection but the client
 973                  * aborts it and starts a new one.
 974                  */
 975                 if (((ct->proto.tcp.seen[dir].flags
 976                       | ct->proto.tcp.seen[!dir].flags)
 977                      & IP_CT_TCP_FLAG_CLOSE_INIT)
 978                     || (ct->proto.tcp.last_dir == dir
 979                         && ct->proto.tcp.last_index == TCP_RST_SET)) {
 980                         /* Attempt to reopen a closed/aborted connection.
 981                          * Delete this connection and look up again. */
 982                         spin_unlock_bh(&ct->lock);
 983
 984                         /* Only repeat if we can actually remove the timer.
 985                          * Destruction may already be in progress in process
 986                          * context and we must give it a chance to terminate.
 987                          */
 988                         if (nf_ct_kill(ct))
 989                                 return -NF_REPEAT;
 990                         return NF_DROP;
 991                 }
 992                 fallthrough;
 993         case TCP_CONNTRACK_IGNORE:
 994                 /* Ignored packets:
 995                  *
 996                  * Our connection entry may be out of sync, so ignore
 997                  * packets which may signal the real connection between
 998                  * the client and the server.
 999                  *
1000                  * a) SYN in ORIGINAL
1001                  * b) SYN/ACK in REPLY
1002                  * c) ACK in reply direction after initial SYN in original.
1003                  *
1004                  * If the ignored packet is invalid, the receiver will send
1005                  * a RST we'll catch below.
1006                  */
1007                 if (index == TCP_SYNACK_SET
1008                     && ct->proto.tcp.last_index == TCP_SYN_SET
1009                     && ct->proto.tcp.last_dir != dir
1010                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1011                         /* b) This SYN/ACK acknowledges a SYN that we earlier
1012                          * ignored as invalid. This means that the client and
1013                          * the server are both in sync, while the firewall is
1014                          * not. We get in sync from the previously annotated
1015                          * values.
1016                          */
1017                         old_state = TCP_CONNTRACK_SYN_SENT;
1018                         new_state = TCP_CONNTRACK_SYN_RECV;
1019                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
1020                                 ct->proto.tcp.last_end;
1021                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
1022                                 ct->proto.tcp.last_end;
1023                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
1024                                 ct->proto.tcp.last_win == 0 ?
1025                                         1 : ct->proto.tcp.last_win;
1026                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
1027                                 ct->proto.tcp.last_wscale;
1028                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1029                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
1030                                 ct->proto.tcp.last_flags;
1031                         nf_ct_tcp_state_reset(&ct->proto.tcp.seen[dir]);
1032                         break;
1033                 }
1034                 ct->proto.tcp.last_index = index;
1035                 ct->proto.tcp.last_dir = dir;
1036                 ct->proto.tcp.last_seq = ntohl(th->seq);
1037                 ct->proto.tcp.last_end =
1038                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
1039                 ct->proto.tcp.last_win = ntohs(th->window);
1040
1041                 /* a) This is a SYN in ORIGINAL. The client and the server
1042                  * may be in sync but we are not. In that case, we annotate
1043                  * the TCP options and let the packet go through. If it is a
1044                  * valid SYN packet, the server will reply with a SYN/ACK, and
1045                  * then we'll get in sync. Otherwise, the server potentially
1046                  * responds with a challenge ACK if implementing RFC5961.
1047                  */
1048                 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
1049                         struct ip_ct_tcp_state seen = {};
1050
1051                         ct->proto.tcp.last_flags =
1052                         ct->proto.tcp.last_wscale = 0;
1053                         tcp_options(skb, dataoff, th, &seen);
1054                         if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1055                                 ct->proto.tcp.last_flags |=
1056                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
1057                                 ct->proto.tcp.last_wscale = seen.td_scale;
1058                         }
1059                         if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
1060                                 ct->proto.tcp.last_flags |=
1061                                         IP_CT_TCP_FLAG_SACK_PERM;
1062                         }
1063                         /* Mark the potential for RFC5961 challenge ACK,
1064                          * this pose a special problem for LAST_ACK state
1065                          * as ACK is intrepretated as ACKing last FIN.
1066                          */
1067                         if (old_state == TCP_CONNTRACK_LAST_ACK)
1068                                 ct->proto.tcp.last_flags |=
1069                                         IP_CT_EXP_CHALLENGE_ACK;
1070                 }
1071
1072                 /* possible challenge ack reply to syn */
1073                 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1074                     index == TCP_ACK_SET &&
1075                     dir == IP_CT_DIR_REPLY)
1076                         ct->proto.tcp.last_ack = ntohl(th->ack_seq);
1077
1078                 spin_unlock_bh(&ct->lock);
1079                 nf_ct_l4proto_log_invalid(skb, ct, state,
1080                                           "packet (index %d) in dir %d ignored, state %s",
1081                                           index, dir,
1082                                           tcp_conntrack_names[old_state]);
1083                 return NF_ACCEPT;
1084         case TCP_CONNTRACK_MAX:
1085                 /* Special case for SYN proxy: when the SYN to the server or
1086                  * the SYN/ACK from the server is lost, the client may transmit
1087                  * a keep-alive packet while in SYN_SENT state. This needs to
1088                  * be associated with the original conntrack entry in order to
1089                  * generate a new SYN with the correct sequence number.
1090                  */
1091                 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
1092                     index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
1093                     ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1094                     ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1095                         pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1096                         spin_unlock_bh(&ct->lock);
1097                         return NF_ACCEPT;
1098                 }
1099
1100                 /* Invalid packet */
1101                 spin_unlock_bh(&ct->lock);
1102                 nf_ct_l4proto_log_invalid(skb, ct, state,
1103                                           "packet (index %d) in dir %d invalid, state %s",
1104                                           index, dir,
1105                                           tcp_conntrack_names[old_state]);
1106                 return -NF_ACCEPT;
1107         case TCP_CONNTRACK_TIME_WAIT:
1108                 /* RFC5961 compliance cause stack to send "challenge-ACK"
1109                  * e.g. in response to spurious SYNs.  Conntrack MUST
1110                  * not believe this ACK is acking last FIN.
1111                  */
1112                 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1113                     index == TCP_ACK_SET &&
1114                     ct->proto.tcp.last_dir != dir &&
1115                     ct->proto.tcp.last_index == TCP_SYN_SET &&
1116                     (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1117                         /* Detected RFC5961 challenge ACK */
1118                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1119                         spin_unlock_bh(&ct->lock);
1120                         nf_ct_l4proto_log_invalid(skb, ct, state, "challenge-ack ignored");
1121                         return NF_ACCEPT; /* Don't change state */
1122                 }
1123                 break;
1124         case TCP_CONNTRACK_SYN_SENT2:
1125                 /* tcp_conntracks table is not smart enough to handle
1126                  * simultaneous open.
1127                  */
1128                 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1129                 break;
1130         case TCP_CONNTRACK_SYN_RECV:
1131                 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1132                     ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1133                         new_state = TCP_CONNTRACK_ESTABLISHED;
1134                 break;
1135         case TCP_CONNTRACK_CLOSE:
1136                 if (index != TCP_RST_SET)
1137                         break;
1138
1139                 /* If we are closing, tuple might have been re-used already.
1140                  * last_index, last_ack, and all other ct fields used for
1141                  * sequence/window validation are outdated in that case.
1142                  *
1143                  * As the conntrack can already be expired by GC under pressure,
1144                  * just skip validation checks.
1145                  */
1146                 if (tcp_can_early_drop(ct))
1147                         goto in_window;
1148
1149                 /* td_maxack might be outdated if we let a SYN through earlier */
1150                 if ((ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) &&
1151                     ct->proto.tcp.last_index != TCP_SYN_SET) {
1152                         u32 seq = ntohl(th->seq);
1153
1154                         /* If we are not in established state and SEQ=0 this is most
1155                          * likely an answer to a SYN we let go through above (last_index
1156                          * can be updated due to out-of-order ACKs).
1157                          */
1158                         if (seq == 0 && !nf_conntrack_tcp_established(ct))
1159                                 break;
1160
1161                         if (before(seq, ct->proto.tcp.seen[!dir].td_maxack) &&
1162                             !tn->tcp_ignore_invalid_rst) {
1163                                 /* Invalid RST  */
1164                                 spin_unlock_bh(&ct->lock);
1165                                 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid rst");
1166                                 return -NF_ACCEPT;
1167                         }
1168
1169                         if (!nf_conntrack_tcp_established(ct) ||
1170                             seq == ct->proto.tcp.seen[!dir].td_maxack)
1171                                 break;
1172
1173                         /* Check if rst is part of train, such as
1174                          *   foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1175                          *   foo:80 > bar:4379: R, 235946602:235946602(0)  ack 42
1176                          */
1177                         if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1178                             ct->proto.tcp.last_dir == dir &&
1179                             seq == ct->proto.tcp.last_end)
1180                                 break;
1181
1182                         /* ... RST sequence number doesn't match exactly, keep
1183                          * established state to allow a possible challenge ACK.
1184                          */
1185                         new_state = old_state;
1186                 }
1187                 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1188                          && ct->proto.tcp.last_index == TCP_SYN_SET)
1189                         || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1190                             && ct->proto.tcp.last_index == TCP_ACK_SET))
1191                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1192                         /* RST sent to invalid SYN or ACK we had let through
1193                          * at a) and c) above:
1194                          *
1195                          * a) SYN was in window then
1196                          * c) we hold a half-open connection.
1197                          *
1198                          * Delete our connection entry.
1199                          * We skip window checking, because packet might ACK
1200                          * segments we ignored. */
1201                         goto in_window;
1202                 }
1203
1204                 /* Reset in response to a challenge-ack we let through earlier */
1205                 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1206                     ct->proto.tcp.last_index == TCP_ACK_SET &&
1207                     ct->proto.tcp.last_dir == IP_CT_DIR_REPLY &&
1208                     ntohl(th->seq) == ct->proto.tcp.last_ack)
1209                         goto in_window;
1210
1211                 break;
1212         default:
1213                 /* Keep compilers happy. */
1214                 break;
1215         }
1216
1217         res = tcp_in_window(ct, dir, index,
1218                             skb, dataoff, th, state);
1219         switch (res) {
1220         case NFCT_TCP_IGNORE:
1221                 spin_unlock_bh(&ct->lock);
1222                 return NF_ACCEPT;
1223         case NFCT_TCP_INVALID:
1224                 nf_tcp_handle_invalid(ct, dir, index, skb, state);
1225                 spin_unlock_bh(&ct->lock);
1226                 return -NF_ACCEPT;
1227         case NFCT_TCP_ACCEPT:
1228                 break;
1229         }
1230      in_window:
1231         /* From now on we have got in-window packets */
1232         ct->proto.tcp.last_index = index;
1233         ct->proto.tcp.last_dir = dir;
1234
1235         pr_debug("tcp_conntracks: ");
1236         nf_ct_dump_tuple(tuple);
1237         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1238                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1239                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1240                  old_state, new_state);
1241
1242         ct->proto.tcp.state = new_state;
1243         if (old_state != new_state
1244             && new_state == TCP_CONNTRACK_FIN_WAIT)
1245                 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1246
1247         timeouts = nf_ct_timeout_lookup(ct);
1248         if (!timeouts)
1249                 timeouts = tn->timeouts;
1250
1251         if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1252             timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1253                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1254         else if (unlikely(index == TCP_RST_SET))
1255                 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1256         else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1257                  IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1258                  timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1259                 timeout = timeouts[TCP_CONNTRACK_UNACK];
1260         else if (ct->proto.tcp.last_win == 0 &&
1261                  timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1262                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1263         else
1264                 timeout = timeouts[new_state];
1265         spin_unlock_bh(&ct->lock);
1266
1267         if (new_state != old_state)
1268                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1269
1270         if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1271                 /* If only reply is a RST, we can consider ourselves not to
1272                    have an established connection: this is a fairly common
1273                    problem case, so we can delete the conntrack
1274                    immediately.  --RR */
1275                 if (th->rst) {
1276                         nf_ct_kill_acct(ct, ctinfo, skb);
1277                         return NF_ACCEPT;
1278                 }
1279
1280                 if (index == TCP_SYN_SET && old_state == TCP_CONNTRACK_SYN_SENT) {
1281                         /* do not renew timeout on SYN retransmit.
1282                          *
1283                          * Else port reuse by client or NAT middlebox can keep
1284                          * entry alive indefinitely (including nat info).
1285                          */
1286                         return NF_ACCEPT;
1287                 }
1288
1289                 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1290                  * pickup with loose=1. Avoid large ESTABLISHED timeout.
1291                  */
1292                 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1293                     timeout > timeouts[TCP_CONNTRACK_UNACK])
1294                         timeout = timeouts[TCP_CONNTRACK_UNACK];
1295         } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1296                    && (old_state == TCP_CONNTRACK_SYN_RECV
1297                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1298                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1299                 /* Set ASSURED if we see valid ack in ESTABLISHED
1300                    after SYN_RECV or a valid answer for a picked up
1301                    connection. */
1302                 set_bit(IPS_ASSURED_BIT, &ct->status);
1303                 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1304         }
1305         nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1306
1307         return NF_ACCEPT;
1308 }
1309
1310 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1311
1312 #include <linux/netfilter/nfnetlink.h>
1313 #include <linux/netfilter/nfnetlink_conntrack.h>
1314
1315 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1316                          struct nf_conn *ct, bool destroy)
1317 {
1318         struct nlattr *nest_parms;
1319         struct nf_ct_tcp_flags tmp = {};
1320
1321         spin_lock_bh(&ct->lock);
1322         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1323         if (!nest_parms)
1324                 goto nla_put_failure;
1325
1326         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1327                 goto nla_put_failure;
1328
1329         if (destroy)
1330                 goto skip_state;
1331
1332         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1333                        ct->proto.tcp.seen[0].td_scale) ||
1334             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1335                        ct->proto.tcp.seen[1].td_scale))
1336                 goto nla_put_failure;
1337
1338         tmp.flags = ct->proto.tcp.seen[0].flags;
1339         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1340                     sizeof(struct nf_ct_tcp_flags), &tmp))
1341                 goto nla_put_failure;
1342
1343         tmp.flags = ct->proto.tcp.seen[1].flags;
1344         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1345                     sizeof(struct nf_ct_tcp_flags), &tmp))
1346                 goto nla_put_failure;
1347 skip_state:
1348         spin_unlock_bh(&ct->lock);
1349         nla_nest_end(skb, nest_parms);
1350
1351         return 0;
1352
1353 nla_put_failure:
1354         spin_unlock_bh(&ct->lock);
1355         return -1;
1356 }
1357
1358 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1359         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1360         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1361         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1362         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1363         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len = sizeof(struct nf_ct_tcp_flags) },
1364 };
1365
1366 #define TCP_NLATTR_SIZE ( \
1367         NLA_ALIGN(NLA_HDRLEN + 1) + \
1368         NLA_ALIGN(NLA_HDRLEN + 1) + \
1369         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1370         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1371
1372 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1373 {
1374         struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1375         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1376         int err;
1377
1378         /* updates could not contain anything about the private
1379          * protocol info, in that case skip the parsing */
1380         if (!pattr)
1381                 return 0;
1382
1383         err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1384                                           tcp_nla_policy, NULL);
1385         if (err < 0)
1386                 return err;
1387
1388         if (tb[CTA_PROTOINFO_TCP_STATE] &&
1389             nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1390                 return -EINVAL;
1391
1392         spin_lock_bh(&ct->lock);
1393         if (tb[CTA_PROTOINFO_TCP_STATE])
1394                 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1395
1396         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1397                 struct nf_ct_tcp_flags *attr =
1398                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1399                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1400                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1401         }
1402
1403         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1404                 struct nf_ct_tcp_flags *attr =
1405                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1406                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1407                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1408         }
1409
1410         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1411             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1412             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1413             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1414                 ct->proto.tcp.seen[0].td_scale =
1415                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1416                 ct->proto.tcp.seen[1].td_scale =
1417                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1418         }
1419         spin_unlock_bh(&ct->lock);
1420
1421         return 0;
1422 }
1423
1424 static unsigned int tcp_nlattr_tuple_size(void)
1425 {
1426         static unsigned int size __read_mostly;
1427
1428         if (!size)
1429                 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1430
1431         return size;
1432 }
1433 #endif
1434
1435 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1436
1437 #include <linux/netfilter/nfnetlink.h>
1438 #include <linux/netfilter/nfnetlink_cttimeout.h>
1439
1440 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1441                                      struct net *net, void *data)
1442 {
1443         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1444         unsigned int *timeouts = data;
1445         int i;
1446
1447         if (!timeouts)
1448                 timeouts = tn->timeouts;
1449         /* set default TCP timeouts. */
1450         for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1451                 timeouts[i] = tn->timeouts[i];
1452
1453         if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1454                 timeouts[TCP_CONNTRACK_SYN_SENT] =
1455                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1456         }
1457
1458         if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1459                 timeouts[TCP_CONNTRACK_SYN_RECV] =
1460                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1461         }
1462         if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1463                 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1464                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1465         }
1466         if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1467                 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1468                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1469         }
1470         if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1471                 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1472                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1473         }
1474         if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1475                 timeouts[TCP_CONNTRACK_LAST_ACK] =
1476                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1477         }
1478         if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1479                 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1480                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1481         }
1482         if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1483                 timeouts[TCP_CONNTRACK_CLOSE] =
1484                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1485         }
1486         if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1487                 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1488                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1489         }
1490         if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1491                 timeouts[TCP_CONNTRACK_RETRANS] =
1492                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1493         }
1494         if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1495                 timeouts[TCP_CONNTRACK_UNACK] =
1496                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1497         }
1498
1499         timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1500         return 0;
1501 }
1502
1503 static int
1504 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1505 {
1506         const unsigned int *timeouts = data;
1507
1508         if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1509                         htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1510             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1511                          htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1512             nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1513                          htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1514             nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1515                          htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1516             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1517                          htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1518             nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1519                          htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1520             nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1521                          htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1522             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1523                          htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1524             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1525                          htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1526             nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1527                          htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1528             nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1529                          htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1530                 goto nla_put_failure;
1531         return 0;
1532
1533 nla_put_failure:
1534         return -ENOSPC;
1535 }
1536
1537 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1538         [CTA_TIMEOUT_TCP_SYN_SENT]      = { .type = NLA_U32 },
1539         [CTA_TIMEOUT_TCP_SYN_RECV]      = { .type = NLA_U32 },
1540         [CTA_TIMEOUT_TCP_ESTABLISHED]   = { .type = NLA_U32 },
1541         [CTA_TIMEOUT_TCP_FIN_WAIT]      = { .type = NLA_U32 },
1542         [CTA_TIMEOUT_TCP_CLOSE_WAIT]    = { .type = NLA_U32 },
1543         [CTA_TIMEOUT_TCP_LAST_ACK]      = { .type = NLA_U32 },
1544         [CTA_TIMEOUT_TCP_TIME_WAIT]     = { .type = NLA_U32 },
1545         [CTA_TIMEOUT_TCP_CLOSE]         = { .type = NLA_U32 },
1546         [CTA_TIMEOUT_TCP_SYN_SENT2]     = { .type = NLA_U32 },
1547         [CTA_TIMEOUT_TCP_RETRANS]       = { .type = NLA_U32 },
1548         [CTA_TIMEOUT_TCP_UNACK]         = { .type = NLA_U32 },
1549 };
1550 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1551
1552 void nf_conntrack_tcp_init_net(struct net *net)
1553 {
1554         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1555         int i;
1556
1557         for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1558                 tn->timeouts[i] = tcp_timeouts[i];
1559
1560         /* timeouts[0] is unused, make it same as SYN_SENT so
1561          * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1562          */
1563         tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1564
1565         /* If it is set to zero, we disable picking up already established
1566          * connections.
1567          */
1568         tn->tcp_loose = 1;
1569
1570         /* "Be conservative in what you do,
1571          *  be liberal in what you accept from others."
1572          * If it's non-zero, we mark only out of window RST segments as INVALID.
1573          */
1574         tn->tcp_be_liberal = 0;
1575
1576         /* If it's non-zero, we turn off RST sequence number check */
1577         tn->tcp_ignore_invalid_rst = 0;
1578
1579         /* Max number of the retransmitted packets without receiving an (acceptable)
1580          * ACK from the destination. If this number is reached, a shorter timer
1581          * will be started.
1582          */
1583         tn->tcp_max_retrans = 3;
1584
1585 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
1586         tn->offload_timeout = 30 * HZ;
1587 #endif
1588 }
1589
1590 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1591 {
1592         .l4proto                = IPPROTO_TCP,
1593 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1594         .print_conntrack        = tcp_print_conntrack,
1595 #endif
1596         .can_early_drop         = tcp_can_early_drop,
1597 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1598         .to_nlattr              = tcp_to_nlattr,
1599         .from_nlattr            = nlattr_to_tcp,
1600         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1601         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1602         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1603         .nlattr_size            = TCP_NLATTR_SIZE,
1604         .nla_policy             = nf_ct_port_nla_policy,
1605 #endif
1606 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1607         .ctnl_timeout           = {
1608                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1609                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1610                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1611                 .obj_size       = sizeof(unsigned int) *
1612                                         TCP_CONNTRACK_TIMEOUT_MAX,
1613                 .nla_policy     = tcp_timeout_nla_policy,
1614         },
1615 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1616 };