net/netfilter/nf_conntrack_proto_tcp.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  * (C) 2002-2013 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
   4  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/timer.h>
  13 #include <linux/module.h>
  14 #include <linux/in.h>
  15 #include <linux/tcp.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/ipv6.h>
  19 #include <net/ip6_checksum.h>
  20 #include <asm/unaligned.h>
  21
  22 #include <net/tcp.h>
  23
  24 #include <linux/netfilter.h>
  25 #include <linux/netfilter_ipv4.h>
  26 #include <linux/netfilter_ipv6.h>
  27 #include <net/netfilter/nf_conntrack.h>
  28 #include <net/netfilter/nf_conntrack_l4proto.h>
  29 #include <net/netfilter/nf_conntrack_ecache.h>
  30 #include <net/netfilter/nf_conntrack_seqadj.h>
  31 #include <net/netfilter/nf_conntrack_synproxy.h>
  32 #include <net/netfilter/nf_log.h>
  33 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  34 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  35
  36 /* "Be conservative in what you do,
  37     be liberal in what you accept from others."
  38     If it's non-zero, we mark only out of window RST segments as INVALID. */
  39 static int nf_ct_tcp_be_liberal __read_mostly = 0;
  40
  41 /* If it is set to zero, we disable picking up already established
  42    connections. */
  43 static int nf_ct_tcp_loose __read_mostly = 1;
  44
  45 /* Max number of the retransmitted packets without receiving an (acceptable)
  46    ACK from the destination. If this number is reached, a shorter timer
  47    will be started. */
  48 static int nf_ct_tcp_max_retrans __read_mostly = 3;
  49
  50   /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
  51      closely.  They're more complex. --RR */
  52
  53 static const char *const tcp_conntrack_names[] = {
  54         "NONE",
  55         "SYN_SENT",
  56         "SYN_RECV",
  57         "ESTABLISHED",
  58         "FIN_WAIT",
  59         "CLOSE_WAIT",
  60         "LAST_ACK",
  61         "TIME_WAIT",
  62         "CLOSE",
  63         "SYN_SENT2",
  64 };
  65
  66 #define SECS * HZ
  67 #define MINS * 60 SECS
  68 #define HOURS * 60 MINS
  69 #define DAYS * 24 HOURS
  70
  71 static unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] __read_mostly = {
  72         [TCP_CONNTRACK_SYN_SENT]        = 2 MINS,
  73         [TCP_CONNTRACK_SYN_RECV]        = 60 SECS,
  74         [TCP_CONNTRACK_ESTABLISHED]     = 5 DAYS,
  75         [TCP_CONNTRACK_FIN_WAIT]        = 2 MINS,
  76         [TCP_CONNTRACK_CLOSE_WAIT]      = 60 SECS,
  77         [TCP_CONNTRACK_LAST_ACK]        = 30 SECS,
  78         [TCP_CONNTRACK_TIME_WAIT]       = 2 MINS,
  79         [TCP_CONNTRACK_CLOSE]           = 10 SECS,
  80         [TCP_CONNTRACK_SYN_SENT2]       = 2 MINS,
  81 /* RFC1122 says the R2 limit should be at least 100 seconds.
  82    Linux uses 15 packets as limit, which corresponds
  83    to ~13-30min depending on RTO. */
  84         [TCP_CONNTRACK_RETRANS]         = 5 MINS,
  85         [TCP_CONNTRACK_UNACK]           = 5 MINS,
  86 };
  87
  88 #define sNO TCP_CONNTRACK_NONE
  89 #define sSS TCP_CONNTRACK_SYN_SENT
  90 #define sSR TCP_CONNTRACK_SYN_RECV
  91 #define sES TCP_CONNTRACK_ESTABLISHED
  92 #define sFW TCP_CONNTRACK_FIN_WAIT
  93 #define sCW TCP_CONNTRACK_CLOSE_WAIT
  94 #define sLA TCP_CONNTRACK_LAST_ACK
  95 #define sTW TCP_CONNTRACK_TIME_WAIT
  96 #define sCL TCP_CONNTRACK_CLOSE
  97 #define sS2 TCP_CONNTRACK_SYN_SENT2
  98 #define sIV TCP_CONNTRACK_MAX
  99 #define sIG TCP_CONNTRACK_IGNORE
 100
 101 /* What TCP flags are set from RST/SYN/FIN/ACK. */
 102 enum tcp_bit_set {
 103         TCP_SYN_SET,
 104         TCP_SYNACK_SET,
 105         TCP_FIN_SET,
 106         TCP_ACK_SET,
 107         TCP_RST_SET,
 108         TCP_NONE_SET,
 109 };
 110
 111 /*
 112  * The TCP state transition table needs a few words...
 113  *
 114  * We are the man in the middle. All the packets go through us
 115  * but might get lost in transit to the destination.
 116  * It is assumed that the destinations can't receive segments
 117  * we haven't seen.
 118  *
 119  * The checked segment is in window, but our windows are *not*
 120  * equivalent with the ones of the sender/receiver. We always
 121  * try to guess the state of the current sender.
 122  *
 123  * The meaning of the states are:
 124  *
 125  * NONE:        initial state
 126  * SYN_SENT:    SYN-only packet seen
 127  * SYN_SENT2:   SYN-only packet seen from reply dir, simultaneous open
 128  * SYN_RECV:    SYN-ACK packet seen
 129  * ESTABLISHED: ACK packet seen
 130  * FIN_WAIT:    FIN packet seen
 131  * CLOSE_WAIT:  ACK seen (after FIN)
 132  * LAST_ACK:    FIN seen (after FIN)
 133  * TIME_WAIT:   last ACK seen
 134  * CLOSE:       closed connection (RST)
 135  *
 136  * Packets marked as IGNORED (sIG):
 137  *      if they may be either invalid or valid
 138  *      and the receiver may send back a connection
 139  *      closing RST or a SYN/ACK.
 140  *
 141  * Packets marked as INVALID (sIV):
 142  *      if we regard them as truly invalid packets
 143  */
 144 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
 145         {
 146 /* ORIGINAL */
 147 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 148 /*syn*/    { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
 149 /*
 150  *      sNO -> sSS      Initialize a new connection
 151  *      sSS -> sSS      Retransmitted SYN
 152  *      sS2 -> sS2      Late retransmitted SYN
 153  *      sSR -> sIG
 154  *      sES -> sIG      Error: SYNs in window outside the SYN_SENT state
 155  *                      are errors. Receiver will reply with RST
 156  *                      and close the connection.
 157  *                      Or we are not in sync and hold a dead connection.
 158  *      sFW -> sIG
 159  *      sCW -> sIG
 160  *      sLA -> sIG
 161  *      sTW -> sSS      Reopened connection (RFC 1122).
 162  *      sCL -> sSS
 163  */
 164 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 165 /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
 166 /*
 167  *      sNO -> sIV      Too late and no reason to do anything
 168  *      sSS -> sIV      Client can't send SYN and then SYN/ACK
 169  *      sS2 -> sSR      SYN/ACK sent to SYN2 in simultaneous open
 170  *      sSR -> sSR      Late retransmitted SYN/ACK in simultaneous open
 171  *      sES -> sIV      Invalid SYN/ACK packets sent by the client
 172  *      sFW -> sIV
 173  *      sCW -> sIV
 174  *      sLA -> sIV
 175  *      sTW -> sIV
 176  *      sCL -> sIV
 177  */
 178 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 179 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 180 /*
 181  *      sNO -> sIV      Too late and no reason to do anything...
 182  *      sSS -> sIV      Client migth not send FIN in this state:
 183  *                      we enforce waiting for a SYN/ACK reply first.
 184  *      sS2 -> sIV
 185  *      sSR -> sFW      Close started.
 186  *      sES -> sFW
 187  *      sFW -> sLA      FIN seen in both directions, waiting for
 188  *                      the last ACK.
 189  *                      Migth be a retransmitted FIN as well...
 190  *      sCW -> sLA
 191  *      sLA -> sLA      Retransmitted FIN. Remain in the same state.
 192  *      sTW -> sTW
 193  *      sCL -> sCL
 194  */
 195 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 196 /*ack*/    { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
 197 /*
 198  *      sNO -> sES      Assumed.
 199  *      sSS -> sIV      ACK is invalid: we haven't seen a SYN/ACK yet.
 200  *      sS2 -> sIV
 201  *      sSR -> sES      Established state is reached.
 202  *      sES -> sES      :-)
 203  *      sFW -> sCW      Normal close request answered by ACK.
 204  *      sCW -> sCW
 205  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 206  *      sTW -> sTW      Retransmitted last ACK. Remain in the same state.
 207  *      sCL -> sCL
 208  */
 209 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 210 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 211 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 212         },
 213         {
 214 /* REPLY */
 215 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 216 /*syn*/    { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
 217 /*
 218  *      sNO -> sIV      Never reached.
 219  *      sSS -> sS2      Simultaneous open
 220  *      sS2 -> sS2      Retransmitted simultaneous SYN
 221  *      sSR -> sIV      Invalid SYN packets sent by the server
 222  *      sES -> sIV
 223  *      sFW -> sIV
 224  *      sCW -> sIV
 225  *      sLA -> sIV
 226  *      sTW -> sSS      Reopened connection, but server may have switched role
 227  *      sCL -> sIV
 228  */
 229 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 230 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
 231 /*
 232  *      sSS -> sSR      Standard open.
 233  *      sS2 -> sSR      Simultaneous open
 234  *      sSR -> sIG      Retransmitted SYN/ACK, ignore it.
 235  *      sES -> sIG      Late retransmitted SYN/ACK?
 236  *      sFW -> sIG      Might be SYN/ACK answering ignored SYN
 237  *      sCW -> sIG
 238  *      sLA -> sIG
 239  *      sTW -> sIG
 240  *      sCL -> sIG
 241  */
 242 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 243 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
 244 /*
 245  *      sSS -> sIV      Server might not send FIN in this state.
 246  *      sS2 -> sIV
 247  *      sSR -> sFW      Close started.
 248  *      sES -> sFW
 249  *      sFW -> sLA      FIN seen in both directions.
 250  *      sCW -> sLA
 251  *      sLA -> sLA      Retransmitted FIN.
 252  *      sTW -> sTW
 253  *      sCL -> sCL
 254  */
 255 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 256 /*ack*/    { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
 257 /*
 258  *      sSS -> sIG      Might be a half-open connection.
 259  *      sS2 -> sIG
 260  *      sSR -> sSR      Might answer late resent SYN.
 261  *      sES -> sES      :-)
 262  *      sFW -> sCW      Normal close request answered by ACK.
 263  *      sCW -> sCW
 264  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
 265  *      sTW -> sTW      Retransmitted last ACK.
 266  *      sCL -> sCL
 267  */
 268 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
 269 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
 270 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
 271         }
 272 };
 273
 274 static inline struct nf_tcp_net *tcp_pernet(struct net *net)
 275 {
 276         return &net->ct.nf_ct_proto.tcp;
 277 }
 278
 279 static bool tcp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
 280                              struct net *net, struct nf_conntrack_tuple *tuple)
 281 {
 282         const struct tcphdr *hp;
 283         struct tcphdr _hdr;
 284
 285         /* Actually only need first 4 bytes to get ports. */
 286         hp = skb_header_pointer(skb, dataoff, 4, &_hdr);
 287         if (hp == NULL)
 288                 return false;
 289
 290         tuple->src.u.tcp.port = hp->source;
 291         tuple->dst.u.tcp.port = hp->dest;
 292
 293         return true;
 294 }
 295
 296 static bool tcp_invert_tuple(struct nf_conntrack_tuple *tuple,
 297                              const struct nf_conntrack_tuple *orig)
 298 {
 299         tuple->src.u.tcp.port = orig->dst.u.tcp.port;
 300         tuple->dst.u.tcp.port = orig->src.u.tcp.port;
 301         return true;
 302 }
 303
 304 #ifdef CONFIG_NF_CONNTRACK_PROCFS
 305 /* Print out the private part of the conntrack. */
 306 static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
 307 {
 308         seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
 309 }
 310 #endif
 311
 312 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
 313 {
 314         if (tcph->rst) return TCP_RST_SET;
 315         else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
 316         else if (tcph->fin) return TCP_FIN_SET;
 317         else if (tcph->ack) return TCP_ACK_SET;
 318         else return TCP_NONE_SET;
 319 }
 320
 321 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
 322    in IP Filter' by Guido van Rooij.
 323
 324    http://www.sane.nl/events/sane2000/papers.html
 325    http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
 326
 327    The boundaries and the conditions are changed according to RFC793:
 328    the packet must intersect the window (i.e. segments may be
 329    after the right or before the left edge) and thus receivers may ACK
 330    segments after the right edge of the window.
 331
 332         td_maxend = max(sack + max(win,1)) seen in reply packets
 333         td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
 334         td_maxwin += seq + len - sender.td_maxend
 335                         if seq + len > sender.td_maxend
 336         td_end    = max(seq + len) seen in sent packets
 337
 338    I.   Upper bound for valid data:     seq <= sender.td_maxend
 339    II.  Lower bound for valid data:     seq + len >= sender.td_end - receiver.td_maxwin
 340    III. Upper bound for valid (s)ack:   sack <= receiver.td_end
 341    IV.  Lower bound for valid (s)ack:   sack >= receiver.td_end - MAXACKWINDOW
 342
 343    where sack is the highest right edge of sack block found in the packet
 344    or ack in the case of packet without SACK option.
 345
 346    The upper bound limit for a valid (s)ack is not ignored -
 347    we doesn't have to deal with fragments.
 348 */
 349
 350 static inline __u32 segment_seq_plus_len(__u32 seq,
 351                                          size_t len,
 352                                          unsigned int dataoff,
 353                                          const struct tcphdr *tcph)
 354 {
 355         /* XXX Should I use payload length field in IP/IPv6 header ?
 356          * - YK */
 357         return (seq + len - dataoff - tcph->doff*4
 358                 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
 359 }
 360
 361 /* Fixme: what about big packets? */
 362 #define MAXACKWINCONST                  66000
 363 #define MAXACKWINDOW(sender)                                            \
 364         ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin     \
 365                                               : MAXACKWINCONST)
 366
 367 /*
 368  * Simplified tcp_parse_options routine from tcp_input.c
 369  */
 370 static void tcp_options(const struct sk_buff *skb,
 371                         unsigned int dataoff,
 372                         const struct tcphdr *tcph,
 373                         struct ip_ct_tcp_state *state)
 374 {
 375         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 376         const unsigned char *ptr;
 377         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 378
 379         if (!length)
 380                 return;
 381
 382         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 383                                  length, buff);
 384         BUG_ON(ptr == NULL);
 385
 386         state->td_scale = 0;
 387         state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
 388
 389         while (length > 0) {
 390                 int opcode=*ptr++;
 391                 int opsize;
 392
 393                 switch (opcode) {
 394                 case TCPOPT_EOL:
 395                         return;
 396                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 397                         length--;
 398                         continue;
 399                 default:
 400                         if (length < 2)
 401                                 return;
 402                         opsize=*ptr++;
 403                         if (opsize < 2) /* "silly options" */
 404                                 return;
 405                         if (opsize > length)
 406                                 return; /* don't parse partial options */
 407
 408                         if (opcode == TCPOPT_SACK_PERM
 409                             && opsize == TCPOLEN_SACK_PERM)
 410                                 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
 411                         else if (opcode == TCPOPT_WINDOW
 412                                  && opsize == TCPOLEN_WINDOW) {
 413                                 state->td_scale = *(u_int8_t *)ptr;
 414
 415                                 if (state->td_scale > TCP_MAX_WSCALE)
 416                                         state->td_scale = TCP_MAX_WSCALE;
 417
 418                                 state->flags |=
 419                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 420                         }
 421                         ptr += opsize - 2;
 422                         length -= opsize;
 423                 }
 424         }
 425 }
 426
 427 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
 428                      const struct tcphdr *tcph, __u32 *sack)
 429 {
 430         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
 431         const unsigned char *ptr;
 432         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 433         __u32 tmp;
 434
 435         if (!length)
 436                 return;
 437
 438         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
 439                                  length, buff);
 440         BUG_ON(ptr == NULL);
 441
 442         /* Fast path for timestamp-only option */
 443         if (length == TCPOLEN_TSTAMP_ALIGNED
 444             && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
 445                                        | (TCPOPT_NOP << 16)
 446                                        | (TCPOPT_TIMESTAMP << 8)
 447                                        | TCPOLEN_TIMESTAMP))
 448                 return;
 449
 450         while (length > 0) {
 451                 int opcode = *ptr++;
 452                 int opsize, i;
 453
 454                 switch (opcode) {
 455                 case TCPOPT_EOL:
 456                         return;
 457                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
 458                         length--;
 459                         continue;
 460                 default:
 461                         if (length < 2)
 462                                 return;
 463                         opsize = *ptr++;
 464                         if (opsize < 2) /* "silly options" */
 465                                 return;
 466                         if (opsize > length)
 467                                 return; /* don't parse partial options */
 468
 469                         if (opcode == TCPOPT_SACK
 470                             && opsize >= (TCPOLEN_SACK_BASE
 471                                           + TCPOLEN_SACK_PERBLOCK)
 472                             && !((opsize - TCPOLEN_SACK_BASE)
 473                                  % TCPOLEN_SACK_PERBLOCK)) {
 474                                 for (i = 0;
 475                                      i < (opsize - TCPOLEN_SACK_BASE);
 476                                      i += TCPOLEN_SACK_PERBLOCK) {
 477                                         tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
 478
 479                                         if (after(tmp, *sack))
 480                                                 *sack = tmp;
 481                                 }
 482                                 return;
 483                         }
 484                         ptr += opsize - 2;
 485                         length -= opsize;
 486                 }
 487         }
 488 }
 489
 490 static bool tcp_in_window(const struct nf_conn *ct,
 491                           struct ip_ct_tcp *state,
 492                           enum ip_conntrack_dir dir,
 493                           unsigned int index,
 494                           const struct sk_buff *skb,
 495                           unsigned int dataoff,
 496                           const struct tcphdr *tcph,
 497                           u_int8_t pf)
 498 {
 499         struct net *net = nf_ct_net(ct);
 500         struct nf_tcp_net *tn = tcp_pernet(net);
 501         struct ip_ct_tcp_state *sender = &state->seen[dir];
 502         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 503         const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
 504         __u32 seq, ack, sack, end, win, swin;
 505         s32 receiver_offset;
 506         bool res, in_recv_win;
 507
 508         /*
 509          * Get the required data from the packet.
 510          */
 511         seq = ntohl(tcph->seq);
 512         ack = sack = ntohl(tcph->ack_seq);
 513         win = ntohs(tcph->window);
 514         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
 515
 516         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
 517                 tcp_sack(skb, dataoff, tcph, &sack);
 518
 519         /* Take into account NAT sequence number mangling */
 520         receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
 521         ack -= receiver_offset;
 522         sack -= receiver_offset;
 523
 524         pr_debug("tcp_in_window: START\n");
 525         pr_debug("tcp_in_window: ");
 526         nf_ct_dump_tuple(tuple);
 527         pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
 528                  seq, ack, receiver_offset, sack, receiver_offset, win, end);
 529         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 530                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 531                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 532                  sender->td_scale,
 533                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 534                  receiver->td_scale);
 535
 536         if (sender->td_maxwin == 0) {
 537                 /*
 538                  * Initialize sender data.
 539                  */
 540                 if (tcph->syn) {
 541                         /*
 542                          * SYN-ACK in reply to a SYN
 543                          * or SYN from reply direction in simultaneous open.
 544                          */
 545                         sender->td_end =
 546                         sender->td_maxend = end;
 547                         sender->td_maxwin = (win == 0 ? 1 : win);
 548
 549                         tcp_options(skb, dataoff, tcph, sender);
 550                         /*
 551                          * RFC 1323:
 552                          * Both sides must send the Window Scale option
 553                          * to enable window scaling in either direction.
 554                          */
 555                         if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
 556                               && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
 557                                 sender->td_scale =
 558                                 receiver->td_scale = 0;
 559                         if (!tcph->ack)
 560                                 /* Simultaneous open */
 561                                 return true;
 562                 } else {
 563                         /*
 564                          * We are in the middle of a connection,
 565                          * its history is lost for us.
 566                          * Let's try to use the data from the packet.
 567                          */
 568                         sender->td_end = end;
 569                         swin = win << sender->td_scale;
 570                         sender->td_maxwin = (swin == 0 ? 1 : swin);
 571                         sender->td_maxend = end + sender->td_maxwin;
 572                         /*
 573                          * We haven't seen traffic in the other direction yet
 574                          * but we have to tweak window tracking to pass III
 575                          * and IV until that happens.
 576                          */
 577                         if (receiver->td_maxwin == 0)
 578                                 receiver->td_end = receiver->td_maxend = sack;
 579                 }
 580         } else if (((state->state == TCP_CONNTRACK_SYN_SENT
 581                      && dir == IP_CT_DIR_ORIGINAL)
 582                    || (state->state == TCP_CONNTRACK_SYN_RECV
 583                      && dir == IP_CT_DIR_REPLY))
 584                    && after(end, sender->td_end)) {
 585                 /*
 586                  * RFC 793: "if a TCP is reinitialized ... then it need
 587                  * not wait at all; it must only be sure to use sequence
 588                  * numbers larger than those recently used."
 589                  */
 590                 sender->td_end =
 591                 sender->td_maxend = end;
 592                 sender->td_maxwin = (win == 0 ? 1 : win);
 593
 594                 tcp_options(skb, dataoff, tcph, sender);
 595         }
 596
 597         if (!(tcph->ack)) {
 598                 /*
 599                  * If there is no ACK, just pretend it was set and OK.
 600                  */
 601                 ack = sack = receiver->td_end;
 602         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
 603                     (TCP_FLAG_ACK|TCP_FLAG_RST))
 604                    && (ack == 0)) {
 605                 /*
 606                  * Broken TCP stacks, that set ACK in RST packets as well
 607                  * with zero ack value.
 608                  */
 609                 ack = sack = receiver->td_end;
 610         }
 611
 612         if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
 613                 /*
 614                  * RST sent answering SYN.
 615                  */
 616                 seq = end = sender->td_end;
 617
 618         pr_debug("tcp_in_window: ");
 619         nf_ct_dump_tuple(tuple);
 620         pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
 621                  seq, ack, receiver_offset, sack, receiver_offset, win, end);
 622         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
 623                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
 624                  sender->td_end, sender->td_maxend, sender->td_maxwin,
 625                  sender->td_scale,
 626                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
 627                  receiver->td_scale);
 628
 629         /* Is the ending sequence in the receive window (if available)? */
 630         in_recv_win = !receiver->td_maxwin ||
 631                       after(end, sender->td_end - receiver->td_maxwin - 1);
 632
 633         pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
 634                  before(seq, sender->td_maxend + 1),
 635                  (in_recv_win ? 1 : 0),
 636                  before(sack, receiver->td_end + 1),
 637                  after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
 638
 639         if (before(seq, sender->td_maxend + 1) &&
 640             in_recv_win &&
 641             before(sack, receiver->td_end + 1) &&
 642             after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
 643                 /*
 644                  * Take into account window scaling (RFC 1323).
 645                  */
 646                 if (!tcph->syn)
 647                         win <<= sender->td_scale;
 648
 649                 /*
 650                  * Update sender data.
 651                  */
 652                 swin = win + (sack - ack);
 653                 if (sender->td_maxwin < swin)
 654                         sender->td_maxwin = swin;
 655                 if (after(end, sender->td_end)) {
 656                         sender->td_end = end;
 657                         sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 658                 }
 659                 if (tcph->ack) {
 660                         if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
 661                                 sender->td_maxack = ack;
 662                                 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
 663                         } else if (after(ack, sender->td_maxack))
 664                                 sender->td_maxack = ack;
 665                 }
 666
 667                 /*
 668                  * Update receiver data.
 669                  */
 670                 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
 671                         receiver->td_maxwin += end - sender->td_maxend;
 672                 if (after(sack + win, receiver->td_maxend - 1)) {
 673                         receiver->td_maxend = sack + win;
 674                         if (win == 0)
 675                                 receiver->td_maxend++;
 676                 }
 677                 if (ack == receiver->td_end)
 678                         receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
 679
 680                 /*
 681                  * Check retransmissions.
 682                  */
 683                 if (index == TCP_ACK_SET) {
 684                         if (state->last_dir == dir
 685                             && state->last_seq == seq
 686                             && state->last_ack == ack
 687                             && state->last_end == end
 688                             && state->last_win == win)
 689                                 state->retrans++;
 690                         else {
 691                                 state->last_dir = dir;
 692                                 state->last_seq = seq;
 693                                 state->last_ack = ack;
 694                                 state->last_end = end;
 695                                 state->last_win = win;
 696                                 state->retrans = 0;
 697                         }
 698                 }
 699                 res = true;
 700         } else {
 701                 res = false;
 702                 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
 703                     tn->tcp_be_liberal)
 704                         res = true;
 705                 if (!res && LOG_INVALID(net, IPPROTO_TCP))
 706                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 707                         "nf_ct_tcp: %s ",
 708                         before(seq, sender->td_maxend + 1) ?
 709                         in_recv_win ?
 710                         before(sack, receiver->td_end + 1) ?
 711                         after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
 712                         : "ACK is under the lower bound (possible overly delayed ACK)"
 713                         : "ACK is over the upper bound (ACKed data not seen yet)"
 714                         : "SEQ is under the lower bound (already ACKed data retransmitted)"
 715                         : "SEQ is over the upper bound (over the window of the receiver)");
 716         }
 717
 718         pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
 719                  "receiver end=%u maxend=%u maxwin=%u\n",
 720                  res, sender->td_end, sender->td_maxend, sender->td_maxwin,
 721                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
 722
 723         return res;
 724 }
 725
 726 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
 727 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
 728                                  TCPHDR_URG) + 1] =
 729 {
 730         [TCPHDR_SYN]                            = 1,
 731         [TCPHDR_SYN|TCPHDR_URG]                 = 1,
 732         [TCPHDR_SYN|TCPHDR_ACK]                 = 1,
 733         [TCPHDR_RST]                            = 1,
 734         [TCPHDR_RST|TCPHDR_ACK]                 = 1,
 735         [TCPHDR_FIN|TCPHDR_ACK]                 = 1,
 736         [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG]      = 1,
 737         [TCPHDR_ACK]                            = 1,
 738         [TCPHDR_ACK|TCPHDR_URG]                 = 1,
 739 };
 740
 741 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
 742 static int tcp_error(struct net *net, struct nf_conn *tmpl,
 743                      struct sk_buff *skb,
 744                      unsigned int dataoff,
 745                      u_int8_t pf,
 746                      unsigned int hooknum)
 747 {
 748         const struct tcphdr *th;
 749         struct tcphdr _tcph;
 750         unsigned int tcplen = skb->len - dataoff;
 751         u_int8_t tcpflags;
 752
 753         /* Smaller that minimal TCP header? */
 754         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 755         if (th == NULL) {
 756                 if (LOG_INVALID(net, IPPROTO_TCP))
 757                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 758                                 "nf_ct_tcp: short packet ");
 759                 return -NF_ACCEPT;
 760         }
 761
 762         /* Not whole TCP header or malformed packet */
 763         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
 764                 if (LOG_INVALID(net, IPPROTO_TCP))
 765                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 766                                 "nf_ct_tcp: truncated/malformed packet ");
 767                 return -NF_ACCEPT;
 768         }
 769
 770         /* Checksum invalid? Ignore.
 771          * We skip checking packets on the outgoing path
 772          * because the checksum is assumed to be correct.
 773          */
 774         /* FIXME: Source route IP option packets --RR */
 775         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 776             nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
 777                 if (LOG_INVALID(net, IPPROTO_TCP))
 778                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 779                                   "nf_ct_tcp: bad TCP checksum ");
 780                 return -NF_ACCEPT;
 781         }
 782
 783         /* Check TCP flags. */
 784         tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
 785         if (!tcp_valid_flags[tcpflags]) {
 786                 if (LOG_INVALID(net, IPPROTO_TCP))
 787                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 788                                   "nf_ct_tcp: invalid TCP flag combination ");
 789                 return -NF_ACCEPT;
 790         }
 791
 792         return NF_ACCEPT;
 793 }
 794
 795 static unsigned int *tcp_get_timeouts(struct net *net)
 796 {
 797         return tcp_pernet(net)->timeouts;
 798 }
 799
 800 static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state)
 801 {
 802         state->td_end           = 0;
 803         state->td_maxend        = 0;
 804         state->td_maxwin        = 0;
 805         state->td_maxack        = 0;
 806         state->td_scale         = 0;
 807         state->flags            &= IP_CT_TCP_FLAG_BE_LIBERAL;
 808 }
 809
 810 /* Returns verdict for packet, or -1 for invalid. */
 811 static int tcp_packet(struct nf_conn *ct,
 812                       const struct sk_buff *skb,
 813                       unsigned int dataoff,
 814                       enum ip_conntrack_info ctinfo,
 815                       u_int8_t pf,
 816                       unsigned int *timeouts)
 817 {
 818         struct net *net = nf_ct_net(ct);
 819         struct nf_tcp_net *tn = tcp_pernet(net);
 820         struct nf_conntrack_tuple *tuple;
 821         enum tcp_conntrack new_state, old_state;
 822         enum ip_conntrack_dir dir;
 823         const struct tcphdr *th;
 824         struct tcphdr _tcph;
 825         unsigned long timeout;
 826         unsigned int index;
 827
 828         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
 829         BUG_ON(th == NULL);
 830
 831         spin_lock_bh(&ct->lock);
 832         old_state = ct->proto.tcp.state;
 833         dir = CTINFO2DIR(ctinfo);
 834         index = get_conntrack_index(th);
 835         new_state = tcp_conntracks[dir][index][old_state];
 836         tuple = &ct->tuplehash[dir].tuple;
 837
 838         switch (new_state) {
 839         case TCP_CONNTRACK_SYN_SENT:
 840                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
 841                         break;
 842                 /* RFC 1122: "When a connection is closed actively,
 843                  * it MUST linger in TIME-WAIT state for a time 2xMSL
 844                  * (Maximum Segment Lifetime). However, it MAY accept
 845                  * a new SYN from the remote TCP to reopen the connection
 846                  * directly from TIME-WAIT state, if..."
 847                  * We ignore the conditions because we are in the
 848                  * TIME-WAIT state anyway.
 849                  *
 850                  * Handle aborted connections: we and the server
 851                  * think there is an existing connection but the client
 852                  * aborts it and starts a new one.
 853                  */
 854                 if (((ct->proto.tcp.seen[dir].flags
 855                       | ct->proto.tcp.seen[!dir].flags)
 856                      & IP_CT_TCP_FLAG_CLOSE_INIT)
 857                     || (ct->proto.tcp.last_dir == dir
 858                         && ct->proto.tcp.last_index == TCP_RST_SET)) {
 859                         /* Attempt to reopen a closed/aborted connection.
 860                          * Delete this connection and look up again. */
 861                         spin_unlock_bh(&ct->lock);
 862
 863                         /* Only repeat if we can actually remove the timer.
 864                          * Destruction may already be in progress in process
 865                          * context and we must give it a chance to terminate.
 866                          */
 867                         if (nf_ct_kill(ct))
 868                                 return -NF_REPEAT;
 869                         return NF_DROP;
 870                 }
 871                 /* Fall through */
 872         case TCP_CONNTRACK_IGNORE:
 873                 /* Ignored packets:
 874                  *
 875                  * Our connection entry may be out of sync, so ignore
 876                  * packets which may signal the real connection between
 877                  * the client and the server.
 878                  *
 879                  * a) SYN in ORIGINAL
 880                  * b) SYN/ACK in REPLY
 881                  * c) ACK in reply direction after initial SYN in original.
 882                  *
 883                  * If the ignored packet is invalid, the receiver will send
 884                  * a RST we'll catch below.
 885                  */
 886                 if (index == TCP_SYNACK_SET
 887                     && ct->proto.tcp.last_index == TCP_SYN_SET
 888                     && ct->proto.tcp.last_dir != dir
 889                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
 890                         /* b) This SYN/ACK acknowledges a SYN that we earlier
 891                          * ignored as invalid. This means that the client and
 892                          * the server are both in sync, while the firewall is
 893                          * not. We get in sync from the previously annotated
 894                          * values.
 895                          */
 896                         old_state = TCP_CONNTRACK_SYN_SENT;
 897                         new_state = TCP_CONNTRACK_SYN_RECV;
 898                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
 899                                 ct->proto.tcp.last_end;
 900                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
 901                                 ct->proto.tcp.last_end;
 902                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
 903                                 ct->proto.tcp.last_win == 0 ?
 904                                         1 : ct->proto.tcp.last_win;
 905                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
 906                                 ct->proto.tcp.last_wscale;
 907                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
 908                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
 909                                 ct->proto.tcp.last_flags;
 910                         nf_ct_tcp_state_reset(&ct->proto.tcp.seen[dir]);
 911                         break;
 912                 }
 913                 ct->proto.tcp.last_index = index;
 914                 ct->proto.tcp.last_dir = dir;
 915                 ct->proto.tcp.last_seq = ntohl(th->seq);
 916                 ct->proto.tcp.last_end =
 917                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
 918                 ct->proto.tcp.last_win = ntohs(th->window);
 919
 920                 /* a) This is a SYN in ORIGINAL. The client and the server
 921                  * may be in sync but we are not. In that case, we annotate
 922                  * the TCP options and let the packet go through. If it is a
 923                  * valid SYN packet, the server will reply with a SYN/ACK, and
 924                  * then we'll get in sync. Otherwise, the server potentially
 925                  * responds with a challenge ACK if implementing RFC5961.
 926                  */
 927                 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
 928                         struct ip_ct_tcp_state seen = {};
 929
 930                         ct->proto.tcp.last_flags =
 931                         ct->proto.tcp.last_wscale = 0;
 932                         tcp_options(skb, dataoff, th, &seen);
 933                         if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
 934                                 ct->proto.tcp.last_flags |=
 935                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
 936                                 ct->proto.tcp.last_wscale = seen.td_scale;
 937                         }
 938                         if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
 939                                 ct->proto.tcp.last_flags |=
 940                                         IP_CT_TCP_FLAG_SACK_PERM;
 941                         }
 942                         /* Mark the potential for RFC5961 challenge ACK,
 943                          * this pose a special problem for LAST_ACK state
 944                          * as ACK is intrepretated as ACKing last FIN.
 945                          */
 946                         if (old_state == TCP_CONNTRACK_LAST_ACK)
 947                                 ct->proto.tcp.last_flags |=
 948                                         IP_CT_EXP_CHALLENGE_ACK;
 949                 }
 950                 spin_unlock_bh(&ct->lock);
 951                 if (LOG_INVALID(net, IPPROTO_TCP))
 952                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 953                                   "nf_ct_tcp: invalid packet ignored in "
 954                                   "state %s ", tcp_conntrack_names[old_state]);
 955                 return NF_ACCEPT;
 956         case TCP_CONNTRACK_MAX:
 957                 /* Special case for SYN proxy: when the SYN to the server or
 958                  * the SYN/ACK from the server is lost, the client may transmit
 959                  * a keep-alive packet while in SYN_SENT state. This needs to
 960                  * be associated with the original conntrack entry in order to
 961                  * generate a new SYN with the correct sequence number.
 962                  */
 963                 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
 964                     index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
 965                     ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
 966                     ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
 967                         pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
 968                         spin_unlock_bh(&ct->lock);
 969                         return NF_ACCEPT;
 970                 }
 971
 972                 /* Invalid packet */
 973                 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
 974                          dir, get_conntrack_index(th), old_state);
 975                 spin_unlock_bh(&ct->lock);
 976                 if (LOG_INVALID(net, IPPROTO_TCP))
 977                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 978                                   "nf_ct_tcp: invalid state ");
 979                 return -NF_ACCEPT;
 980         case TCP_CONNTRACK_TIME_WAIT:
 981                 /* RFC5961 compliance cause stack to send "challenge-ACK"
 982                  * e.g. in response to spurious SYNs.  Conntrack MUST
 983                  * not believe this ACK is acking last FIN.
 984                  */
 985                 if (old_state == TCP_CONNTRACK_LAST_ACK &&
 986                     index == TCP_ACK_SET &&
 987                     ct->proto.tcp.last_dir != dir &&
 988                     ct->proto.tcp.last_index == TCP_SYN_SET &&
 989                     (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
 990                         /* Detected RFC5961 challenge ACK */
 991                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
 992                         spin_unlock_bh(&ct->lock);
 993                         if (LOG_INVALID(net, IPPROTO_TCP))
 994                                 nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 995                                       "nf_ct_tcp: challenge-ACK ignored ");
 996                         return NF_ACCEPT; /* Don't change state */
 997                 }
 998                 break;
 999         case TCP_CONNTRACK_CLOSE:
1000                 if (index == TCP_RST_SET
1001                     && (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET)
1002                     && before(ntohl(th->seq), ct->proto.tcp.seen[!dir].td_maxack)) {
1003                         /* Invalid RST  */
1004                         spin_unlock_bh(&ct->lock);
1005                         if (LOG_INVALID(net, IPPROTO_TCP))
1006                                 nf_log_packet(net, pf, 0, skb, NULL, NULL,
1007                                               NULL, "nf_ct_tcp: invalid RST ");
1008                         return -NF_ACCEPT;
1009                 }
1010                 if (index == TCP_RST_SET
1011                     && ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1012                          && ct->proto.tcp.last_index == TCP_SYN_SET)
1013                         || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1014                             && ct->proto.tcp.last_index == TCP_ACK_SET))
1015                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1016                         /* RST sent to invalid SYN or ACK we had let through
1017                          * at a) and c) above:
1018                          *
1019                          * a) SYN was in window then
1020                          * c) we hold a half-open connection.
1021                          *
1022                          * Delete our connection entry.
1023                          * We skip window checking, because packet might ACK
1024                          * segments we ignored. */
1025                         goto in_window;
1026                 }
1027                 /* Just fall through */
1028         default:
1029                 /* Keep compilers happy. */
1030                 break;
1031         }
1032
1033         if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
1034                            skb, dataoff, th, pf)) {
1035                 spin_unlock_bh(&ct->lock);
1036                 return -NF_ACCEPT;
1037         }
1038      in_window:
1039         /* From now on we have got in-window packets */
1040         ct->proto.tcp.last_index = index;
1041         ct->proto.tcp.last_dir = dir;
1042
1043         pr_debug("tcp_conntracks: ");
1044         nf_ct_dump_tuple(tuple);
1045         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1046                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1047                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1048                  old_state, new_state);
1049
1050         ct->proto.tcp.state = new_state;
1051         if (old_state != new_state
1052             && new_state == TCP_CONNTRACK_FIN_WAIT)
1053                 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1054
1055         if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1056             timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1057                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1058         else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1059                  IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1060                  timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1061                 timeout = timeouts[TCP_CONNTRACK_UNACK];
1062         else
1063                 timeout = timeouts[new_state];
1064         spin_unlock_bh(&ct->lock);
1065
1066         if (new_state != old_state)
1067                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1068
1069         if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1070                 /* If only reply is a RST, we can consider ourselves not to
1071                    have an established connection: this is a fairly common
1072                    problem case, so we can delete the conntrack
1073                    immediately.  --RR */
1074                 if (th->rst) {
1075                         nf_ct_kill_acct(ct, ctinfo, skb);
1076                         return NF_ACCEPT;
1077                 }
1078                 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1079                  * pickup with loose=1. Avoid large ESTABLISHED timeout.
1080                  */
1081                 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1082                     timeout > timeouts[TCP_CONNTRACK_UNACK])
1083                         timeout = timeouts[TCP_CONNTRACK_UNACK];
1084         } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1085                    && (old_state == TCP_CONNTRACK_SYN_RECV
1086                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1087                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1088                 /* Set ASSURED if we see see valid ack in ESTABLISHED
1089                    after SYN_RECV or a valid answer for a picked up
1090                    connection. */
1091                 set_bit(IPS_ASSURED_BIT, &ct->status);
1092                 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1093         }
1094         nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1095
1096         return NF_ACCEPT;
1097 }
1098
1099 /* Called when a new connection for this protocol found. */
1100 static bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
1101                     unsigned int dataoff, unsigned int *timeouts)
1102 {
1103         enum tcp_conntrack new_state;
1104         const struct tcphdr *th;
1105         struct tcphdr _tcph;
1106         struct net *net = nf_ct_net(ct);
1107         struct nf_tcp_net *tn = tcp_pernet(net);
1108         const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
1109         const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
1110
1111         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
1112         BUG_ON(th == NULL);
1113
1114         /* Don't need lock here: this conntrack not in circulation yet */
1115         new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
1116
1117         /* Invalid: delete conntrack */
1118         if (new_state >= TCP_CONNTRACK_MAX) {
1119                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
1120                 return false;
1121         }
1122
1123         if (new_state == TCP_CONNTRACK_SYN_SENT) {
1124                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
1125                 /* SYN packet */
1126                 ct->proto.tcp.seen[0].td_end =
1127                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1128                                              dataoff, th);
1129                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1130                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
1131                         ct->proto.tcp.seen[0].td_maxwin = 1;
1132                 ct->proto.tcp.seen[0].td_maxend =
1133                         ct->proto.tcp.seen[0].td_end;
1134
1135                 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
1136         } else if (tn->tcp_loose == 0) {
1137                 /* Don't try to pick up connections. */
1138                 return false;
1139         } else {
1140                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
1141                 /*
1142                  * We are in the middle of a connection,
1143                  * its history is lost for us.
1144                  * Let's try to use the data from the packet.
1145                  */
1146                 ct->proto.tcp.seen[0].td_end =
1147                         segment_seq_plus_len(ntohl(th->seq), skb->len,
1148                                              dataoff, th);
1149                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1150                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
1151                         ct->proto.tcp.seen[0].td_maxwin = 1;
1152                 ct->proto.tcp.seen[0].td_maxend =
1153                         ct->proto.tcp.seen[0].td_end +
1154                         ct->proto.tcp.seen[0].td_maxwin;
1155
1156                 /* We assume SACK and liberal window checking to handle
1157                  * window scaling */
1158                 ct->proto.tcp.seen[0].flags =
1159                 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
1160                                               IP_CT_TCP_FLAG_BE_LIBERAL;
1161         }
1162
1163         /* tcp_packet will set them */
1164         ct->proto.tcp.last_index = TCP_NONE_SET;
1165
1166         pr_debug("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
1167                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
1168                  sender->td_end, sender->td_maxend, sender->td_maxwin,
1169                  sender->td_scale,
1170                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
1171                  receiver->td_scale);
1172         return true;
1173 }
1174
1175 static bool tcp_can_early_drop(const struct nf_conn *ct)
1176 {
1177         switch (ct->proto.tcp.state) {
1178         case TCP_CONNTRACK_FIN_WAIT:
1179         case TCP_CONNTRACK_LAST_ACK:
1180         case TCP_CONNTRACK_TIME_WAIT:
1181         case TCP_CONNTRACK_CLOSE:
1182         case TCP_CONNTRACK_CLOSE_WAIT:
1183                 return true;
1184         default:
1185                 break;
1186         }
1187
1188         return false;
1189 }
1190
1191 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1192
1193 #include <linux/netfilter/nfnetlink.h>
1194 #include <linux/netfilter/nfnetlink_conntrack.h>
1195
1196 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1197                          struct nf_conn *ct)
1198 {
1199         struct nlattr *nest_parms;
1200         struct nf_ct_tcp_flags tmp = {};
1201
1202         spin_lock_bh(&ct->lock);
1203         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP | NLA_F_NESTED);
1204         if (!nest_parms)
1205                 goto nla_put_failure;
1206
1207         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state) ||
1208             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1209                        ct->proto.tcp.seen[0].td_scale) ||
1210             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1211                        ct->proto.tcp.seen[1].td_scale))
1212                 goto nla_put_failure;
1213
1214         tmp.flags = ct->proto.tcp.seen[0].flags;
1215         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1216                     sizeof(struct nf_ct_tcp_flags), &tmp))
1217                 goto nla_put_failure;
1218
1219         tmp.flags = ct->proto.tcp.seen[1].flags;
1220         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1221                     sizeof(struct nf_ct_tcp_flags), &tmp))
1222                 goto nla_put_failure;
1223         spin_unlock_bh(&ct->lock);
1224
1225         nla_nest_end(skb, nest_parms);
1226
1227         return 0;
1228
1229 nla_put_failure:
1230         spin_unlock_bh(&ct->lock);
1231         return -1;
1232 }
1233
1234 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1235         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1236         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1237         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1238         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1239         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len =  sizeof(struct nf_ct_tcp_flags) },
1240 };
1241
1242 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1243 {
1244         struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1245         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1246         int err;
1247
1248         /* updates could not contain anything about the private
1249          * protocol info, in that case skip the parsing */
1250         if (!pattr)
1251                 return 0;
1252
1253         err = nla_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1254                                tcp_nla_policy, NULL);
1255         if (err < 0)
1256                 return err;
1257
1258         if (tb[CTA_PROTOINFO_TCP_STATE] &&
1259             nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1260                 return -EINVAL;
1261
1262         spin_lock_bh(&ct->lock);
1263         if (tb[CTA_PROTOINFO_TCP_STATE])
1264                 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1265
1266         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1267                 struct nf_ct_tcp_flags *attr =
1268                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1269                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1270                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1271         }
1272
1273         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1274                 struct nf_ct_tcp_flags *attr =
1275                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1276                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1277                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1278         }
1279
1280         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1281             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1282             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1283             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1284                 ct->proto.tcp.seen[0].td_scale =
1285                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1286                 ct->proto.tcp.seen[1].td_scale =
1287                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1288         }
1289         spin_unlock_bh(&ct->lock);
1290
1291         return 0;
1292 }
1293
1294 static int tcp_nlattr_size(void)
1295 {
1296         return nla_total_size(0)           /* CTA_PROTOINFO_TCP */
1297                 + nla_policy_len(tcp_nla_policy, CTA_PROTOINFO_TCP_MAX + 1);
1298 }
1299
1300 static int tcp_nlattr_tuple_size(void)
1301 {
1302         return nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1303 }
1304 #endif
1305
1306 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
1307
1308 #include <linux/netfilter/nfnetlink.h>
1309 #include <linux/netfilter/nfnetlink_cttimeout.h>
1310
1311 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1312                                      struct net *net, void *data)
1313 {
1314         unsigned int *timeouts = data;
1315         struct nf_tcp_net *tn = tcp_pernet(net);
1316         int i;
1317
1318         /* set default TCP timeouts. */
1319         for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1320                 timeouts[i] = tn->timeouts[i];
1321
1322         if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1323                 timeouts[TCP_CONNTRACK_SYN_SENT] =
1324                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1325         }
1326         if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1327                 timeouts[TCP_CONNTRACK_SYN_RECV] =
1328                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1329         }
1330         if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1331                 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1332                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1333         }
1334         if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1335                 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1336                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1337         }
1338         if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1339                 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1340                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1341         }
1342         if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1343                 timeouts[TCP_CONNTRACK_LAST_ACK] =
1344                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1345         }
1346         if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1347                 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1348                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1349         }
1350         if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1351                 timeouts[TCP_CONNTRACK_CLOSE] =
1352                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1353         }
1354         if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1355                 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1356                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1357         }
1358         if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1359                 timeouts[TCP_CONNTRACK_RETRANS] =
1360                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1361         }
1362         if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1363                 timeouts[TCP_CONNTRACK_UNACK] =
1364                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1365         }
1366         return 0;
1367 }
1368
1369 static int
1370 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1371 {
1372         const unsigned int *timeouts = data;
1373
1374         if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1375                         htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1376             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1377                          htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1378             nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1379                          htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1380             nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1381                          htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1382             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1383                          htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1384             nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1385                          htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1386             nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1387                          htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1388             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1389                          htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1390             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1391                          htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1392             nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1393                          htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1394             nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1395                          htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1396                 goto nla_put_failure;
1397         return 0;
1398
1399 nla_put_failure:
1400         return -ENOSPC;
1401 }
1402
1403 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1404         [CTA_TIMEOUT_TCP_SYN_SENT]      = { .type = NLA_U32 },
1405         [CTA_TIMEOUT_TCP_SYN_RECV]      = { .type = NLA_U32 },
1406         [CTA_TIMEOUT_TCP_ESTABLISHED]   = { .type = NLA_U32 },
1407         [CTA_TIMEOUT_TCP_FIN_WAIT]      = { .type = NLA_U32 },
1408         [CTA_TIMEOUT_TCP_CLOSE_WAIT]    = { .type = NLA_U32 },
1409         [CTA_TIMEOUT_TCP_LAST_ACK]      = { .type = NLA_U32 },
1410         [CTA_TIMEOUT_TCP_TIME_WAIT]     = { .type = NLA_U32 },
1411         [CTA_TIMEOUT_TCP_CLOSE]         = { .type = NLA_U32 },
1412         [CTA_TIMEOUT_TCP_SYN_SENT2]     = { .type = NLA_U32 },
1413         [CTA_TIMEOUT_TCP_RETRANS]       = { .type = NLA_U32 },
1414         [CTA_TIMEOUT_TCP_UNACK]         = { .type = NLA_U32 },
1415 };
1416 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
1417
1418 #ifdef CONFIG_SYSCTL
1419 static struct ctl_table tcp_sysctl_table[] = {
1420         {
1421                 .procname       = "nf_conntrack_tcp_timeout_syn_sent",
1422                 .maxlen         = sizeof(unsigned int),
1423                 .mode           = 0644,
1424                 .proc_handler   = proc_dointvec_jiffies,
1425         },
1426         {
1427                 .procname       = "nf_conntrack_tcp_timeout_syn_recv",
1428                 .maxlen         = sizeof(unsigned int),
1429                 .mode           = 0644,
1430                 .proc_handler   = proc_dointvec_jiffies,
1431         },
1432         {
1433                 .procname       = "nf_conntrack_tcp_timeout_established",
1434                 .maxlen         = sizeof(unsigned int),
1435                 .mode           = 0644,
1436                 .proc_handler   = proc_dointvec_jiffies,
1437         },
1438         {
1439                 .procname       = "nf_conntrack_tcp_timeout_fin_wait",
1440                 .maxlen         = sizeof(unsigned int),
1441                 .mode           = 0644,
1442                 .proc_handler   = proc_dointvec_jiffies,
1443         },
1444         {
1445                 .procname       = "nf_conntrack_tcp_timeout_close_wait",
1446                 .maxlen         = sizeof(unsigned int),
1447                 .mode           = 0644,
1448                 .proc_handler   = proc_dointvec_jiffies,
1449         },
1450         {
1451                 .procname       = "nf_conntrack_tcp_timeout_last_ack",
1452                 .maxlen         = sizeof(unsigned int),
1453                 .mode           = 0644,
1454                 .proc_handler   = proc_dointvec_jiffies,
1455         },
1456         {
1457                 .procname       = "nf_conntrack_tcp_timeout_time_wait",
1458                 .maxlen         = sizeof(unsigned int),
1459                 .mode           = 0644,
1460                 .proc_handler   = proc_dointvec_jiffies,
1461         },
1462         {
1463                 .procname       = "nf_conntrack_tcp_timeout_close",
1464                 .maxlen         = sizeof(unsigned int),
1465                 .mode           = 0644,
1466                 .proc_handler   = proc_dointvec_jiffies,
1467         },
1468         {
1469                 .procname       = "nf_conntrack_tcp_timeout_max_retrans",
1470                 .maxlen         = sizeof(unsigned int),
1471                 .mode           = 0644,
1472                 .proc_handler   = proc_dointvec_jiffies,
1473         },
1474         {
1475                 .procname       = "nf_conntrack_tcp_timeout_unacknowledged",
1476                 .maxlen         = sizeof(unsigned int),
1477                 .mode           = 0644,
1478                 .proc_handler   = proc_dointvec_jiffies,
1479         },
1480         {
1481                 .procname       = "nf_conntrack_tcp_loose",
1482                 .maxlen         = sizeof(unsigned int),
1483                 .mode           = 0644,
1484                 .proc_handler   = proc_dointvec,
1485         },
1486         {
1487                 .procname       = "nf_conntrack_tcp_be_liberal",
1488                 .maxlen         = sizeof(unsigned int),
1489                 .mode           = 0644,
1490                 .proc_handler   = proc_dointvec,
1491         },
1492         {
1493                 .procname       = "nf_conntrack_tcp_max_retrans",
1494                 .maxlen         = sizeof(unsigned int),
1495                 .mode           = 0644,
1496                 .proc_handler   = proc_dointvec,
1497         },
1498         { }
1499 };
1500 #endif /* CONFIG_SYSCTL */
1501
1502 static int tcp_kmemdup_sysctl_table(struct nf_proto_net *pn,
1503                                     struct nf_tcp_net *tn)
1504 {
1505 #ifdef CONFIG_SYSCTL
1506         if (pn->ctl_table)
1507                 return 0;
1508
1509         pn->ctl_table = kmemdup(tcp_sysctl_table,
1510                                 sizeof(tcp_sysctl_table),
1511                                 GFP_KERNEL);
1512         if (!pn->ctl_table)
1513                 return -ENOMEM;
1514
1515         pn->ctl_table[0].data = &tn->timeouts[TCP_CONNTRACK_SYN_SENT];
1516         pn->ctl_table[1].data = &tn->timeouts[TCP_CONNTRACK_SYN_RECV];
1517         pn->ctl_table[2].data = &tn->timeouts[TCP_CONNTRACK_ESTABLISHED];
1518         pn->ctl_table[3].data = &tn->timeouts[TCP_CONNTRACK_FIN_WAIT];
1519         pn->ctl_table[4].data = &tn->timeouts[TCP_CONNTRACK_CLOSE_WAIT];
1520         pn->ctl_table[5].data = &tn->timeouts[TCP_CONNTRACK_LAST_ACK];
1521         pn->ctl_table[6].data = &tn->timeouts[TCP_CONNTRACK_TIME_WAIT];
1522         pn->ctl_table[7].data = &tn->timeouts[TCP_CONNTRACK_CLOSE];
1523         pn->ctl_table[8].data = &tn->timeouts[TCP_CONNTRACK_RETRANS];
1524         pn->ctl_table[9].data = &tn->timeouts[TCP_CONNTRACK_UNACK];
1525         pn->ctl_table[10].data = &tn->tcp_loose;
1526         pn->ctl_table[11].data = &tn->tcp_be_liberal;
1527         pn->ctl_table[12].data = &tn->tcp_max_retrans;
1528 #endif
1529         return 0;
1530 }
1531
1532 static int tcp_init_net(struct net *net, u_int16_t proto)
1533 {
1534         struct nf_tcp_net *tn = tcp_pernet(net);
1535         struct nf_proto_net *pn = &tn->pn;
1536
1537         if (!pn->users) {
1538                 int i;
1539
1540                 for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1541                         tn->timeouts[i] = tcp_timeouts[i];
1542
1543                 tn->tcp_loose = nf_ct_tcp_loose;
1544                 tn->tcp_be_liberal = nf_ct_tcp_be_liberal;
1545                 tn->tcp_max_retrans = nf_ct_tcp_max_retrans;
1546         }
1547
1548         return tcp_kmemdup_sysctl_table(pn, tn);
1549 }
1550
1551 static struct nf_proto_net *tcp_get_net_proto(struct net *net)
1552 {
1553         return &net->ct.nf_ct_proto.tcp.pn;
1554 }
1555
1556 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 __read_mostly =
1557 {
1558         .l3proto                = PF_INET,
1559         .l4proto                = IPPROTO_TCP,
1560         .pkt_to_tuple           = tcp_pkt_to_tuple,
1561         .invert_tuple           = tcp_invert_tuple,
1562 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1563         .print_conntrack        = tcp_print_conntrack,
1564 #endif
1565         .packet                 = tcp_packet,
1566         .get_timeouts           = tcp_get_timeouts,
1567         .new                    = tcp_new,
1568         .error                  = tcp_error,
1569         .can_early_drop         = tcp_can_early_drop,
1570 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1571         .to_nlattr              = tcp_to_nlattr,
1572         .nlattr_size            = tcp_nlattr_size,
1573         .from_nlattr            = nlattr_to_tcp,
1574         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1575         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1576         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1577         .nla_policy             = nf_ct_port_nla_policy,
1578 #endif
1579 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
1580         .ctnl_timeout           = {
1581                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1582                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1583                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1584                 .obj_size       = sizeof(unsigned int) *
1585                                         TCP_CONNTRACK_TIMEOUT_MAX,
1586                 .nla_policy     = tcp_timeout_nla_policy,
1587         },
1588 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
1589         .init_net               = tcp_init_net,
1590         .get_net_proto          = tcp_get_net_proto,
1591 };
1592 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp4);
1593
1594 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp6 __read_mostly =
1595 {
1596         .l3proto                = PF_INET6,
1597         .l4proto                = IPPROTO_TCP,
1598         .pkt_to_tuple           = tcp_pkt_to_tuple,
1599         .invert_tuple           = tcp_invert_tuple,
1600 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1601         .print_conntrack        = tcp_print_conntrack,
1602 #endif
1603         .packet                 = tcp_packet,
1604         .get_timeouts           = tcp_get_timeouts,
1605         .new                    = tcp_new,
1606         .error                  = tcp_error,
1607         .can_early_drop         = tcp_can_early_drop,
1608 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1609         .to_nlattr              = tcp_to_nlattr,
1610         .nlattr_size            = tcp_nlattr_size,
1611         .from_nlattr            = nlattr_to_tcp,
1612         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1613         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1614         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1615         .nla_policy             = nf_ct_port_nla_policy,
1616 #endif
1617 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
1618         .ctnl_timeout           = {
1619                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1620                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1621                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1622                 .obj_size       = sizeof(unsigned int) *
1623                                         TCP_CONNTRACK_TIMEOUT_MAX,
1624                 .nla_policy     = tcp_timeout_nla_policy,
1625         },
1626 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
1627         .init_net               = tcp_init_net,
1628         .get_net_proto          = tcp_get_net_proto,
1629 };
1630 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp6);