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
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/if_arp.h>
  17 #include <linux/ip.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/icmpv6.h>
  20 #include <net/udp.h>
  21 #include <net/tcp.h>
  22 #include <net/ipv6.h>
  23 #include <linux/netfilter.h>
  24 #include <linux/netfilter/x_tables.h>
  25 #include <linux/netfilter_ipv6/ip6_tables.h>
  26 #include <net/netfilter/nf_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 /* Use lock to serialize, so printks don't overlap */
  37 static DEFINE_SPINLOCK(log_lock);
  38
  39 /* One level of recursion won't kill us */
  40 static void dump_packet(const struct nf_loginfo *info,
  41                         const struct sk_buff *skb, unsigned int ip6hoff,
  42                         int recurse)
  43 {
  44         u_int8_t currenthdr;
  45         int fragment;
  46         struct ipv6hdr _ip6h;
  47         const struct ipv6hdr *ih;
  48         unsigned int ptr;
  49         unsigned int hdrlen = 0;
  50         unsigned int logflags;
  51
  52         if (info->type == NF_LOG_TYPE_LOG)
  53                 logflags = info->u.log.logflags;
  54         else
  55                 logflags = NF_LOG_MASK;
  56
  57         ih = skb_header_pointer(skb, ip6hoff, sizeof(_ip6h), &_ip6h);
  58         if (ih == NULL) {
  59                 printk("TRUNCATED");
  60                 return;
  61         }
  62
  63         /* Max length: 88 "SRC=0000.0000.0000.0000.0000.0000.0000.0000 DST=0000.0000.0000.0000.0000.0000.0000.0000 " */
  64         printk("SRC=" NIP6_FMT " DST=" NIP6_FMT " ", NIP6(ih->saddr), NIP6(ih->daddr));
  65
  66         /* Max length: 44 "LEN=65535 TC=255 HOPLIMIT=255 FLOWLBL=FFFFF " */
  67         printk("LEN=%Zu TC=%u HOPLIMIT=%u FLOWLBL=%u ",
  68                ntohs(ih->payload_len) + sizeof(struct ipv6hdr),
  69                (ntohl(*(__be32 *)ih) & 0x0ff00000) >> 20,
  70                ih->hop_limit,
  71                (ntohl(*(__be32 *)ih) & 0x000fffff));
  72
  73         fragment = 0;
  74         ptr = ip6hoff + sizeof(struct ipv6hdr);
  75         currenthdr = ih->nexthdr;
  76         while (currenthdr != NEXTHDR_NONE && ip6t_ext_hdr(currenthdr)) {
  77                 struct ipv6_opt_hdr _hdr;
  78                 const struct ipv6_opt_hdr *hp;
  79
  80                 hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
  81                 if (hp == NULL) {
  82                         printk("TRUNCATED");
  83                         return;
  84                 }
  85
  86                 /* Max length: 48 "OPT (...) " */
  87                 if (logflags & IP6T_LOG_IPOPT)
  88                         printk("OPT ( ");
  89
  90                 switch (currenthdr) {
  91                 case IPPROTO_FRAGMENT: {
  92                         struct frag_hdr _fhdr;
  93                         const struct frag_hdr *fh;
  94
  95                         printk("FRAG:");
  96                         fh = skb_header_pointer(skb, ptr, sizeof(_fhdr),
  97                                                 &_fhdr);
  98                         if (fh == NULL) {
  99                                 printk("TRUNCATED ");
 100                                 return;
 101                         }
 102
 103                         /* Max length: 6 "65535 " */
 104                         printk("%u ", ntohs(fh->frag_off) & 0xFFF8);
 105
 106                         /* Max length: 11 "INCOMPLETE " */
 107                         if (fh->frag_off & htons(0x0001))
 108                                 printk("INCOMPLETE ");
 109
 110                         printk("ID:%08x ", ntohl(fh->identification));
 111
 112                         if (ntohs(fh->frag_off) & 0xFFF8)
 113                                 fragment = 1;
 114
 115                         hdrlen = 8;
 116
 117                         break;
 118                 }
 119                 case IPPROTO_DSTOPTS:
 120                 case IPPROTO_ROUTING:
 121                 case IPPROTO_HOPOPTS:
 122                         if (fragment) {
 123                                 if (logflags & IP6T_LOG_IPOPT)
 124                                         printk(")");
 125                                 return;
 126                         }
 127                         hdrlen = ipv6_optlen(hp);
 128                         break;
 129                 /* Max Length */
 130                 case IPPROTO_AH:
 131                         if (logflags & IP6T_LOG_IPOPT) {
 132                                 struct ip_auth_hdr _ahdr;
 133                                 const struct ip_auth_hdr *ah;
 134
 135                                 /* Max length: 3 "AH " */
 136                                 printk("AH ");
 137
 138                                 if (fragment) {
 139                                         printk(")");
 140                                         return;
 141                                 }
 142
 143                                 ah = skb_header_pointer(skb, ptr, sizeof(_ahdr),
 144                                                         &_ahdr);
 145                                 if (ah == NULL) {
 146                                         /*
 147                                          * Max length: 26 "INCOMPLETE [65535
 148                                          *  bytes] )"
 149                                          */
 150                                         printk("INCOMPLETE [%u bytes] )",
 151                                                skb->len - ptr);
 152                                         return;
 153                                 }
 154
 155                                 /* Length: 15 "SPI=0xF1234567 */
 156                                 printk("SPI=0x%x ", ntohl(ah->spi));
 157
 158                         }
 159
 160                         hdrlen = (hp->hdrlen+2)<<2;
 161                         break;
 162                 case IPPROTO_ESP:
 163                         if (logflags & IP6T_LOG_IPOPT) {
 164                                 struct ip_esp_hdr _esph;
 165                                 const struct ip_esp_hdr *eh;
 166
 167                                 /* Max length: 4 "ESP " */
 168                                 printk("ESP ");
 169
 170                                 if (fragment) {
 171                                         printk(")");
 172                                         return;
 173                                 }
 174
 175                                 /*
 176                                  * Max length: 26 "INCOMPLETE [65535 bytes] )"
 177                                  */
 178                                 eh = skb_header_pointer(skb, ptr, sizeof(_esph),
 179                                                         &_esph);
 180                                 if (eh == NULL) {
 181                                         printk("INCOMPLETE [%u bytes] )",
 182                                                skb->len - ptr);
 183                                         return;
 184                                 }
 185
 186                                 /* Length: 16 "SPI=0xF1234567 )" */
 187                                 printk("SPI=0x%x )", ntohl(eh->spi) );
 188
 189                         }
 190                         return;
 191                 default:
 192                         /* Max length: 20 "Unknown Ext Hdr 255" */
 193                         printk("Unknown Ext Hdr %u", currenthdr);
 194                         return;
 195                 }
 196                 if (logflags & IP6T_LOG_IPOPT)
 197                         printk(") ");
 198
 199                 currenthdr = hp->nexthdr;
 200                 ptr += hdrlen;
 201         }
 202
 203         switch (currenthdr) {
 204         case IPPROTO_TCP: {
 205                 struct tcphdr _tcph;
 206                 const struct tcphdr *th;
 207
 208                 /* Max length: 10 "PROTO=TCP " */
 209                 printk("PROTO=TCP ");
 210
 211                 if (fragment)
 212                         break;
 213
 214                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 215                 th = skb_header_pointer(skb, ptr, sizeof(_tcph), &_tcph);
 216                 if (th == NULL) {
 217                         printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
 218                         return;
 219                 }
 220
 221                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 222                 printk("SPT=%u DPT=%u ",
 223                        ntohs(th->source), ntohs(th->dest));
 224                 /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
 225                 if (logflags & IP6T_LOG_TCPSEQ)
 226                         printk("SEQ=%u ACK=%u ",
 227                                ntohl(th->seq), ntohl(th->ack_seq));
 228                 /* Max length: 13 "WINDOW=65535 " */
 229                 printk("WINDOW=%u ", ntohs(th->window));
 230                 /* Max length: 9 "RES=0x3C " */
 231                 printk("RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
 232                 /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
 233                 if (th->cwr)
 234                         printk("CWR ");
 235                 if (th->ece)
 236                         printk("ECE ");
 237                 if (th->urg)
 238                         printk("URG ");
 239                 if (th->ack)
 240                         printk("ACK ");
 241                 if (th->psh)
 242                         printk("PSH ");
 243                 if (th->rst)
 244                         printk("RST ");
 245                 if (th->syn)
 246                         printk("SYN ");
 247                 if (th->fin)
 248                         printk("FIN ");
 249                 /* Max length: 11 "URGP=65535 " */
 250                 printk("URGP=%u ", ntohs(th->urg_ptr));
 251
 252                 if ((logflags & IP6T_LOG_TCPOPT)
 253                     && th->doff * 4 > sizeof(struct tcphdr)) {
 254                         u_int8_t _opt[60 - sizeof(struct tcphdr)];
 255                         const u_int8_t *op;
 256                         unsigned int i;
 257                         unsigned int optsize = th->doff * 4
 258                                                - sizeof(struct tcphdr);
 259
 260                         op = skb_header_pointer(skb,
 261                                                 ptr + sizeof(struct tcphdr),
 262                                                 optsize, _opt);
 263                         if (op == NULL) {
 264                                 printk("OPT (TRUNCATED)");
 265                                 return;
 266                         }
 267
 268                         /* Max length: 127 "OPT (" 15*4*2chars ") " */
 269                         printk("OPT (");
 270                         for (i =0; i < optsize; i++)
 271                                 printk("%02X", op[i]);
 272                         printk(") ");
 273                 }
 274                 break;
 275         }
 276         case IPPROTO_UDP:
 277         case IPPROTO_UDPLITE: {
 278                 struct udphdr _udph;
 279                 const struct udphdr *uh;
 280
 281                 if (currenthdr == IPPROTO_UDP)
 282                         /* Max length: 10 "PROTO=UDP "     */
 283                         printk("PROTO=UDP " );
 284                 else    /* Max length: 14 "PROTO=UDPLITE " */
 285                         printk("PROTO=UDPLITE ");
 286
 287                 if (fragment)
 288                         break;
 289
 290                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 291                 uh = skb_header_pointer(skb, ptr, sizeof(_udph), &_udph);
 292                 if (uh == NULL) {
 293                         printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
 294                         return;
 295                 }
 296
 297                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 298                 printk("SPT=%u DPT=%u LEN=%u ",
 299                        ntohs(uh->source), ntohs(uh->dest),
 300                        ntohs(uh->len));
 301                 break;
 302         }
 303         case IPPROTO_ICMPV6: {
 304                 struct icmp6hdr _icmp6h;
 305                 const struct icmp6hdr *ic;
 306
 307                 /* Max length: 13 "PROTO=ICMPv6 " */
 308                 printk("PROTO=ICMPv6 ");
 309
 310                 if (fragment)
 311                         break;
 312
 313                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 314                 ic = skb_header_pointer(skb, ptr, sizeof(_icmp6h), &_icmp6h);
 315                 if (ic == NULL) {
 316                         printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
 317                         return;
 318                 }
 319
 320                 /* Max length: 18 "TYPE=255 CODE=255 " */
 321                 printk("TYPE=%u CODE=%u ", ic->icmp6_type, ic->icmp6_code);
 322
 323                 switch (ic->icmp6_type) {
 324                 case ICMPV6_ECHO_REQUEST:
 325                 case ICMPV6_ECHO_REPLY:
 326                         /* Max length: 19 "ID=65535 SEQ=65535 " */
 327                         printk("ID=%u SEQ=%u ",
 328                                 ntohs(ic->icmp6_identifier),
 329                                 ntohs(ic->icmp6_sequence));
 330                         break;
 331                 case ICMPV6_MGM_QUERY:
 332                 case ICMPV6_MGM_REPORT:
 333                 case ICMPV6_MGM_REDUCTION:
 334                         break;
 335
 336                 case ICMPV6_PARAMPROB:
 337                         /* Max length: 17 "POINTER=ffffffff " */
 338                         printk("POINTER=%08x ", ntohl(ic->icmp6_pointer));
 339                         /* Fall through */
 340                 case ICMPV6_DEST_UNREACH:
 341                 case ICMPV6_PKT_TOOBIG:
 342                 case ICMPV6_TIME_EXCEED:
 343                         /* Max length: 3+maxlen */
 344                         if (recurse) {
 345                                 printk("[");
 346                                 dump_packet(info, skb, ptr + sizeof(_icmp6h),
 347                                             0);
 348                                 printk("] ");
 349                         }
 350
 351                         /* Max length: 10 "MTU=65535 " */
 352                         if (ic->icmp6_type == ICMPV6_PKT_TOOBIG)
 353                                 printk("MTU=%u ", ntohl(ic->icmp6_mtu));
 354                 }
 355                 break;
 356         }
 357         /* Max length: 10 "PROTO=255 " */
 358         default:
 359                 printk("PROTO=%u ", currenthdr);
 360         }
 361
 362         /* Max length: 15 "UID=4294967295 " */
 363         if ((logflags & IP6T_LOG_UID) && recurse && skb->sk) {
 364                 read_lock_bh(&skb->sk->sk_callback_lock);
 365                 if (skb->sk->sk_socket && skb->sk->sk_socket->file)
 366                         printk("UID=%u GID=%u ",
 367                                 skb->sk->sk_socket->file->f_cred->fsuid,
 368                                 skb->sk->sk_socket->file->f_cred->fsgid);
 369                 read_unlock_bh(&skb->sk->sk_callback_lock);
 370         }
 371
 372         /* Max length: 16 "MARK=0xFFFFFFFF " */
 373         if (!recurse && skb->mark)
 374                 printk("MARK=0x%x ", skb->mark);
 375 }
 376
 377 static struct nf_loginfo default_loginfo = {
 378         .type   = NF_LOG_TYPE_LOG,
 379         .u = {
 380                 .log = {
 381                         .level    = 0,
 382                         .logflags = NF_LOG_MASK,
 383                 },
 384         },
 385 };
 386
 387 static void
 388 ip6t_log_packet(u_int8_t pf,
 389                 unsigned int hooknum,
 390                 const struct sk_buff *skb,
 391                 const struct net_device *in,
 392                 const struct net_device *out,
 393                 const struct nf_loginfo *loginfo,
 394                 const char *prefix)
 395 {
 396         if (!loginfo)
 397                 loginfo = &default_loginfo;
 398
 399         spin_lock_bh(&log_lock);
 400         printk("<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
 401                 prefix,
 402                 in ? in->name : "",
 403                 out ? out->name : "");
 404         if (in && !out) {
 405                 unsigned int len;
 406                 /* MAC logging for input chain only. */
 407                 printk("MAC=");
 408                 if (skb->dev && (len = skb->dev->hard_header_len) &&
 409                     skb->mac_header != skb->network_header) {
 410                         const unsigned char *p = skb_mac_header(skb);
 411                         int i;
 412
 413                         if (skb->dev->type == ARPHRD_SIT &&
 414                             (p -= ETH_HLEN) < skb->head)
 415                                 p = NULL;
 416
 417                         if (p != NULL) {
 418                                 for (i = 0; i < len; i++)
 419                                         printk("%02x%s", p[i],
 420                                                i == len - 1 ? "" : ":");
 421                         }
 422                         printk(" ");
 423
 424                         if (skb->dev->type == ARPHRD_SIT) {
 425                                 const struct iphdr *iph =
 426                                         (struct iphdr *)skb_mac_header(skb);
 427                                 printk("TUNNEL=%u.%u.%u.%u->%u.%u.%u.%u ",
 428                                        NIPQUAD(iph->saddr),
 429                                        NIPQUAD(iph->daddr));
 430                         }
 431                 } else
 432                         printk(" ");
 433         }
 434
 435         dump_packet(loginfo, skb, skb_network_offset(skb), 1);
 436         printk("\n");
 437         spin_unlock_bh(&log_lock);
 438 }
 439
 440 static unsigned int
 441 log_tg6(struct sk_buff *skb, const struct xt_target_param *par)
 442 {
 443         const struct ip6t_log_info *loginfo = par->targinfo;
 444         struct nf_loginfo li;
 445
 446         li.type = NF_LOG_TYPE_LOG;
 447         li.u.log.level = loginfo->level;
 448         li.u.log.logflags = loginfo->logflags;
 449
 450         ip6t_log_packet(NFPROTO_IPV6, par->hooknum, skb, par->in, par->out,
 451                         &li, loginfo->prefix);
 452         return XT_CONTINUE;
 453 }
 454
 455
 456 static bool log_tg6_check(const struct xt_tgchk_param *par)
 457 {
 458         const struct ip6t_log_info *loginfo = par->targinfo;
 459
 460         if (loginfo->level >= 8) {
 461                 pr_debug("LOG: level %u >= 8\n", loginfo->level);
 462                 return false;
 463         }
 464         if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
 465                 pr_debug("LOG: prefix term %i\n",
 466                          loginfo->prefix[sizeof(loginfo->prefix)-1]);
 467                 return false;
 468         }
 469         return true;
 470 }
 471
 472 static struct xt_target log_tg6_reg __read_mostly = {
 473         .name           = "LOG",
 474         .family         = NFPROTO_IPV6,
 475         .target         = log_tg6,
 476         .targetsize     = sizeof(struct ip6t_log_info),
 477         .checkentry     = log_tg6_check,
 478         .me             = THIS_MODULE,
 479 };
 480
 481 static const struct nf_logger ip6t_logger = {
 482         .name           = "ip6t_LOG",
 483         .logfn          = &ip6t_log_packet,
 484         .me             = THIS_MODULE,
 485 };
 486
 487 static int __init log_tg6_init(void)
 488 {
 489         int ret;
 490
 491         ret = xt_register_target(&log_tg6_reg);
 492         if (ret < 0)
 493                 return ret;
 494         nf_log_register(NFPROTO_IPV6, &ip6t_logger);
 495         return 0;
 496 }
 497
 498 static void __exit log_tg6_exit(void)
 499 {
 500         nf_log_unregister(&ip6t_logger);
 501         xt_unregister_target(&log_tg6_reg);
 502 }
 503
 504 module_init(log_tg6_init);
 505 module_exit(log_tg6_exit);