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