net/ipv6/netfilter/ip6t_LOG.c

   1 /*
   2  * This is a module which is used for logging packets.
   3  */
   4
   5 /* (C) 2001 Jan Rekorajski <baggins@pld.org.pl>
   6  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13 #include <linux/module.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/if_arp.h>
  16 #include <linux/ip.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/icmpv6.h>
  19 #include <net/udp.h>
  20 #include <net/tcp.h>
  21 #include <net/ipv6.h>
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter/x_tables.h>
  24 #include <linux/netfilter_ipv6/ip6_tables.h>
  25 #include <net/netfilter/nf_log.h>
  26 #include <net/netfilter/xt_log.h>
  27
  28 MODULE_AUTHOR("Jan Rekorajski <baggins@pld.org.pl>");
  29 MODULE_DESCRIPTION("Xtables: IPv6 packet logging to syslog");
  30 MODULE_LICENSE("GPL");
  31
  32 struct in_device;
  33 #include <net/route.h>
  34 #include <linux/netfilter_ipv6/ip6t_LOG.h>
  35
  36 /* One level of recursion won't kill us */
  37 static void dump_packet(struct sbuff *m,
  38                         const struct nf_loginfo *info,
  39                         const struct sk_buff *skb, unsigned int ip6hoff,
  40                         int recurse)
  41 {
  42         u_int8_t currenthdr;
  43         int fragment;
  44         struct ipv6hdr _ip6h;
  45         const struct ipv6hdr *ih;
  46         unsigned int ptr;
  47         unsigned int hdrlen = 0;
  48         unsigned int logflags;
  49
  50         if (info->type == NF_LOG_TYPE_LOG)
  51                 logflags = info->u.log.logflags;
  52         else
  53                 logflags = NF_LOG_MASK;
  54
  55         ih = skb_header_pointer(skb, ip6hoff, sizeof(_ip6h), &_ip6h);
  56         if (ih == NULL) {
  57                 sb_add(m, "TRUNCATED");
  58                 return;
  59         }
  60
  61         /* Max length: 88 "SRC=0000.0000.0000.0000.0000.0000.0000.0000 DST=0000.0000.0000.0000.0000.0000.0000.0000 " */
  62         sb_add(m, "SRC=%pI6 DST=%pI6 ", &ih->saddr, &ih->daddr);
  63
  64         /* Max length: 44 "LEN=65535 TC=255 HOPLIMIT=255 FLOWLBL=FFFFF " */
  65         sb_add(m, "LEN=%Zu TC=%u HOPLIMIT=%u FLOWLBL=%u ",
  66                ntohs(ih->payload_len) + sizeof(struct ipv6hdr),
  67                (ntohl(*(__be32 *)ih) & 0x0ff00000) >> 20,
  68                ih->hop_limit,
  69                (ntohl(*(__be32 *)ih) & 0x000fffff));
  70
  71         fragment = 0;
  72         ptr = ip6hoff + sizeof(struct ipv6hdr);
  73         currenthdr = ih->nexthdr;
  74         while (currenthdr != NEXTHDR_NONE && ip6t_ext_hdr(currenthdr)) {
  75                 struct ipv6_opt_hdr _hdr;
  76                 const struct ipv6_opt_hdr *hp;
  77
  78                 hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
  79                 if (hp == NULL) {
  80                         sb_add(m, "TRUNCATED");
  81                         return;
  82                 }
  83
  84                 /* Max length: 48 "OPT (...) " */
  85                 if (logflags & IP6T_LOG_IPOPT)
  86                         sb_add(m, "OPT ( ");
  87
  88                 switch (currenthdr) {
  89                 case IPPROTO_FRAGMENT: {
  90                         struct frag_hdr _fhdr;
  91                         const struct frag_hdr *fh;
  92
  93                         sb_add(m, "FRAG:");
  94                         fh = skb_header_pointer(skb, ptr, sizeof(_fhdr),
  95                                                 &_fhdr);
  96                         if (fh == NULL) {
  97                                 sb_add(m, "TRUNCATED ");
  98                                 return;
  99                         }
 100
 101                         /* Max length: 6 "65535 " */
 102                         sb_add(m, "%u ", ntohs(fh->frag_off) & 0xFFF8);
 103
 104                         /* Max length: 11 "INCOMPLETE " */
 105                         if (fh->frag_off & htons(0x0001))
 106                                 sb_add(m, "INCOMPLETE ");
 107
 108                         sb_add(m, "ID:%08x ", ntohl(fh->identification));
 109
 110                         if (ntohs(fh->frag_off) & 0xFFF8)
 111                                 fragment = 1;
 112
 113                         hdrlen = 8;
 114
 115                         break;
 116                 }
 117                 case IPPROTO_DSTOPTS:
 118                 case IPPROTO_ROUTING:
 119                 case IPPROTO_HOPOPTS:
 120                         if (fragment) {
 121                                 if (logflags & IP6T_LOG_IPOPT)
 122                                         sb_add(m, ")");
 123                                 return;
 124                         }
 125                         hdrlen = ipv6_optlen(hp);
 126                         break;
 127                 /* Max Length */
 128                 case IPPROTO_AH:
 129                         if (logflags & IP6T_LOG_IPOPT) {
 130                                 struct ip_auth_hdr _ahdr;
 131                                 const struct ip_auth_hdr *ah;
 132
 133                                 /* Max length: 3 "AH " */
 134                                 sb_add(m, "AH ");
 135
 136                                 if (fragment) {
 137                                         sb_add(m, ")");
 138                                         return;
 139                                 }
 140
 141                                 ah = skb_header_pointer(skb, ptr, sizeof(_ahdr),
 142                                                         &_ahdr);
 143                                 if (ah == NULL) {
 144                                         /*
 145                                          * Max length: 26 "INCOMPLETE [65535
 146                                          *  bytes] )"
 147                                          */
 148                                         sb_add(m, "INCOMPLETE [%u bytes] )",
 149                                                skb->len - ptr);
 150                                         return;
 151                                 }
 152
 153                                 /* Length: 15 "SPI=0xF1234567 */
 154                                 sb_add(m, "SPI=0x%x ", ntohl(ah->spi));
 155
 156                         }
 157
 158                         hdrlen = (hp->hdrlen+2)<<2;
 159                         break;
 160                 case IPPROTO_ESP:
 161                         if (logflags & IP6T_LOG_IPOPT) {
 162                                 struct ip_esp_hdr _esph;
 163                                 const struct ip_esp_hdr *eh;
 164
 165                                 /* Max length: 4 "ESP " */
 166                                 sb_add(m, "ESP ");
 167
 168                                 if (fragment) {
 169                                         sb_add(m, ")");
 170                                         return;
 171                                 }
 172
 173                                 /*
 174                                  * Max length: 26 "INCOMPLETE [65535 bytes] )"
 175                                  */
 176                                 eh = skb_header_pointer(skb, ptr, sizeof(_esph),
 177                                                         &_esph);
 178                                 if (eh == NULL) {
 179                                         sb_add(m, "INCOMPLETE [%u bytes] )",
 180                                                skb->len - ptr);
 181                                         return;
 182                                 }
 183
 184                                 /* Length: 16 "SPI=0xF1234567 )" */
 185                                 sb_add(m, "SPI=0x%x )", ntohl(eh->spi) );
 186
 187                         }
 188                         return;
 189                 default:
 190                         /* Max length: 20 "Unknown Ext Hdr 255" */
 191                         sb_add(m, "Unknown Ext Hdr %u", currenthdr);
 192                         return;
 193                 }
 194                 if (logflags & IP6T_LOG_IPOPT)
 195                         sb_add(m, ") ");
 196
 197                 currenthdr = hp->nexthdr;
 198                 ptr += hdrlen;
 199         }
 200
 201         switch (currenthdr) {
 202         case IPPROTO_TCP: {
 203                 struct tcphdr _tcph;
 204                 const struct tcphdr *th;
 205
 206                 /* Max length: 10 "PROTO=TCP " */
 207                 sb_add(m, "PROTO=TCP ");
 208
 209                 if (fragment)
 210                         break;
 211
 212                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 213                 th = skb_header_pointer(skb, ptr, sizeof(_tcph), &_tcph);
 214                 if (th == NULL) {
 215                         sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
 216                         return;
 217                 }
 218
 219                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 220                 sb_add(m, "SPT=%u DPT=%u ",
 221                        ntohs(th->source), ntohs(th->dest));
 222                 /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
 223                 if (logflags & IP6T_LOG_TCPSEQ)
 224                         sb_add(m, "SEQ=%u ACK=%u ",
 225                                ntohl(th->seq), ntohl(th->ack_seq));
 226                 /* Max length: 13 "WINDOW=65535 " */
 227                 sb_add(m, "WINDOW=%u ", ntohs(th->window));
 228                 /* Max length: 9 "RES=0x3C " */
 229                 sb_add(m, "RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
 230                 /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
 231                 if (th->cwr)
 232                         sb_add(m, "CWR ");
 233                 if (th->ece)
 234                         sb_add(m, "ECE ");
 235                 if (th->urg)
 236                         sb_add(m, "URG ");
 237                 if (th->ack)
 238                         sb_add(m, "ACK ");
 239                 if (th->psh)
 240                         sb_add(m, "PSH ");
 241                 if (th->rst)
 242                         sb_add(m, "RST ");
 243                 if (th->syn)
 244                         sb_add(m, "SYN ");
 245                 if (th->fin)
 246                         sb_add(m, "FIN ");
 247                 /* Max length: 11 "URGP=65535 " */
 248                 sb_add(m, "URGP=%u ", ntohs(th->urg_ptr));
 249
 250                 if ((logflags & IP6T_LOG_TCPOPT) &&
 251                     th->doff * 4 > sizeof(struct tcphdr)) {
 252                         u_int8_t _opt[60 - sizeof(struct tcphdr)];
 253                         const u_int8_t *op;
 254                         unsigned int i;
 255                         unsigned int optsize = th->doff * 4
 256                                                - sizeof(struct tcphdr);
 257
 258                         op = skb_header_pointer(skb,
 259                                                 ptr + sizeof(struct tcphdr),
 260                                                 optsize, _opt);
 261                         if (op == NULL) {
 262                                 sb_add(m, "OPT (TRUNCATED)");
 263                                 return;
 264                         }
 265
 266                         /* Max length: 127 "OPT (" 15*4*2chars ") " */
 267                         sb_add(m, "OPT (");
 268                         for (i =0; i < optsize; i++)
 269                                 sb_add(m, "%02X", op[i]);
 270                         sb_add(m, ") ");
 271                 }
 272                 break;
 273         }
 274         case IPPROTO_UDP:
 275         case IPPROTO_UDPLITE: {
 276                 struct udphdr _udph;
 277                 const struct udphdr *uh;
 278
 279                 if (currenthdr == IPPROTO_UDP)
 280                         /* Max length: 10 "PROTO=UDP "     */
 281                         sb_add(m, "PROTO=UDP " );
 282                 else    /* Max length: 14 "PROTO=UDPLITE " */
 283                         sb_add(m, "PROTO=UDPLITE ");
 284
 285                 if (fragment)
 286                         break;
 287
 288                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 289                 uh = skb_header_pointer(skb, ptr, sizeof(_udph), &_udph);
 290                 if (uh == NULL) {
 291                         sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
 292                         return;
 293                 }
 294
 295                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 296                 sb_add(m, "SPT=%u DPT=%u LEN=%u ",
 297                        ntohs(uh->source), ntohs(uh->dest),
 298                        ntohs(uh->len));
 299                 break;
 300         }
 301         case IPPROTO_ICMPV6: {
 302                 struct icmp6hdr _icmp6h;
 303                 const struct icmp6hdr *ic;
 304
 305                 /* Max length: 13 "PROTO=ICMPv6 " */
 306                 sb_add(m, "PROTO=ICMPv6 ");
 307
 308                 if (fragment)
 309                         break;
 310
 311                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 312                 ic = skb_header_pointer(skb, ptr, sizeof(_icmp6h), &_icmp6h);
 313                 if (ic == NULL) {
 314                         sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
 315                         return;
 316                 }
 317
 318                 /* Max length: 18 "TYPE=255 CODE=255 " */
 319                 sb_add(m, "TYPE=%u CODE=%u ", ic->icmp6_type, ic->icmp6_code);
 320
 321                 switch (ic->icmp6_type) {
 322                 case ICMPV6_ECHO_REQUEST:
 323                 case ICMPV6_ECHO_REPLY:
 324                         /* Max length: 19 "ID=65535 SEQ=65535 " */
 325                         sb_add(m, "ID=%u SEQ=%u ",
 326                                 ntohs(ic->icmp6_identifier),
 327                                 ntohs(ic->icmp6_sequence));
 328                         break;
 329                 case ICMPV6_MGM_QUERY:
 330                 case ICMPV6_MGM_REPORT:
 331                 case ICMPV6_MGM_REDUCTION:
 332                         break;
 333
 334                 case ICMPV6_PARAMPROB:
 335                         /* Max length: 17 "POINTER=ffffffff " */
 336                         sb_add(m, "POINTER=%08x ", ntohl(ic->icmp6_pointer));
 337                         /* Fall through */
 338                 case ICMPV6_DEST_UNREACH:
 339                 case ICMPV6_PKT_TOOBIG:
 340                 case ICMPV6_TIME_EXCEED:
 341                         /* Max length: 3+maxlen */
 342                         if (recurse) {
 343                                 sb_add(m, "[");
 344                                 dump_packet(m, info, skb,
 345                                             ptr + sizeof(_icmp6h), 0);
 346                                 sb_add(m, "] ");
 347                         }
 348
 349                         /* Max length: 10 "MTU=65535 " */
 350                         if (ic->icmp6_type == ICMPV6_PKT_TOOBIG)
 351                                 sb_add(m, "MTU=%u ", ntohl(ic->icmp6_mtu));
 352                 }
 353                 break;
 354         }
 355         /* Max length: 10 "PROTO=255 " */
 356         default:
 357                 sb_add(m, "PROTO=%u ", currenthdr);
 358         }
 359
 360         /* Max length: 15 "UID=4294967295 " */
 361         if ((logflags & IP6T_LOG_UID) && recurse && skb->sk) {
 362                 read_lock_bh(&skb->sk->sk_callback_lock);
 363                 if (skb->sk->sk_socket && skb->sk->sk_socket->file)
 364                         sb_add(m, "UID=%u GID=%u ",
 365                                 skb->sk->sk_socket->file->f_cred->fsuid,
 366                                 skb->sk->sk_socket->file->f_cred->fsgid);
 367                 read_unlock_bh(&skb->sk->sk_callback_lock);
 368         }
 369
 370         /* Max length: 16 "MARK=0xFFFFFFFF " */
 371         if (!recurse && skb->mark)
 372                 sb_add(m, "MARK=0x%x ", skb->mark);
 373 }
 374
 375 static void dump_mac_header(struct sbuff *m,
 376                             const struct nf_loginfo *info,
 377                             const struct sk_buff *skb)
 378 {
 379         struct net_device *dev = skb->dev;
 380         unsigned int logflags = 0;
 381
 382         if (info->type == NF_LOG_TYPE_LOG)
 383                 logflags = info->u.log.logflags;
 384
 385         if (!(logflags & IP6T_LOG_MACDECODE))
 386                 goto fallback;
 387
 388         switch (dev->type) {
 389         case ARPHRD_ETHER:
 390                 sb_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
 391                        eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
 392                        ntohs(eth_hdr(skb)->h_proto));
 393                 return;
 394         default:
 395                 break;
 396         }
 397
 398 fallback:
 399         sb_add(m, "MAC=");
 400         if (dev->hard_header_len &&
 401             skb->mac_header != skb->network_header) {
 402                 const unsigned char *p = skb_mac_header(skb);
 403                 unsigned int len = dev->hard_header_len;
 404                 unsigned int i;
 405
 406                 if (dev->type == ARPHRD_SIT &&
 407                     (p -= ETH_HLEN) < skb->head)
 408                         p = NULL;
 409
 410                 if (p != NULL) {
 411                         sb_add(m, "%02x", *p++);
 412                         for (i = 1; i < len; i++)
 413                                 sb_add(m, ":%02x", p[i]);
 414                 }
 415                 sb_add(m, " ");
 416
 417                 if (dev->type == ARPHRD_SIT) {
 418                         const struct iphdr *iph =
 419                                 (struct iphdr *)skb_mac_header(skb);
 420                         sb_add(m, "TUNNEL=%pI4->%pI4 ", &iph->saddr, &iph->daddr);
 421                 }
 422         } else
 423                 sb_add(m, " ");
 424 }
 425
 426 static struct nf_loginfo default_loginfo = {
 427         .type   = NF_LOG_TYPE_LOG,
 428         .u = {
 429                 .log = {
 430                         .level    = 5,
 431                         .logflags = NF_LOG_MASK,
 432                 },
 433         },
 434 };
 435
 436 static void
 437 ip6t_log_packet(u_int8_t pf,
 438                 unsigned int hooknum,
 439                 const struct sk_buff *skb,
 440                 const struct net_device *in,
 441                 const struct net_device *out,
 442                 const struct nf_loginfo *loginfo,
 443                 const char *prefix)
 444 {
 445         struct sbuff *m = sb_open();
 446
 447         if (!loginfo)
 448                 loginfo = &default_loginfo;
 449
 450         sb_add(m, "<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
 451                prefix,
 452                in ? in->name : "",
 453                out ? out->name : "");
 454
 455         /* MAC logging for input path only. */
 456         if (in && !out)
 457                 dump_mac_header(m, loginfo, skb);
 458
 459         dump_packet(m, loginfo, skb, skb_network_offset(skb), 1);
 460
 461         sb_close(m);
 462 }
 463
 464 static unsigned int
 465 log_tg6(struct sk_buff *skb, const struct xt_action_param *par)
 466 {
 467         const struct ip6t_log_info *loginfo = par->targinfo;
 468         struct nf_loginfo li;
 469
 470         li.type = NF_LOG_TYPE_LOG;
 471         li.u.log.level = loginfo->level;
 472         li.u.log.logflags = loginfo->logflags;
 473
 474         ip6t_log_packet(NFPROTO_IPV6, par->hooknum, skb, par->in, par->out,
 475                         &li, loginfo->prefix);
 476         return XT_CONTINUE;
 477 }
 478
 479
 480 static int log_tg6_check(const struct xt_tgchk_param *par)
 481 {
 482         const struct ip6t_log_info *loginfo = par->targinfo;
 483
 484         if (loginfo->level >= 8) {
 485                 pr_debug("level %u >= 8\n", loginfo->level);
 486                 return -EINVAL;
 487         }
 488         if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
 489                 pr_debug("prefix not null-terminated\n");
 490                 return -EINVAL;
 491         }
 492         return 0;
 493 }
 494
 495 static struct xt_target log_tg6_reg __read_mostly = {
 496         .name           = "LOG",
 497         .family         = NFPROTO_IPV6,
 498         .target         = log_tg6,
 499         .targetsize     = sizeof(struct ip6t_log_info),
 500         .checkentry     = log_tg6_check,
 501         .me             = THIS_MODULE,
 502 };
 503
 504 static struct nf_logger ip6t_logger __read_mostly = {
 505         .name           = "ip6t_LOG",
 506         .logfn          = &ip6t_log_packet,
 507         .me             = THIS_MODULE,
 508 };
 509
 510 static int __init log_tg6_init(void)
 511 {
 512         int ret;
 513
 514         ret = xt_register_target(&log_tg6_reg);
 515         if (ret < 0)
 516                 return ret;
 517         nf_log_register(NFPROTO_IPV6, &ip6t_logger);
 518         return 0;
 519 }
 520
 521 static void __exit log_tg6_exit(void)
 522 {
 523         nf_log_unregister(&ip6t_logger);
 524         xt_unregister_target(&log_tg6_reg);
 525 }
 526
 527 module_init(log_tg6_init);
 528 module_exit(log_tg6_exit);