net/ipv4/netfilter/ipt_LOG.c

   1 /*
   2  * This is a module which is used for logging packets.
   3  */
   4
   5 /* (C) 1999-2001 Paul `Rusty' Russell
   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/spinlock.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/ip.h>
  17 #include <net/icmp.h>
  18 #include <net/udp.h>
  19 #include <net/tcp.h>
  20 #include <net/route.h>
  21
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter_ipv4/ip_tables.h>
  24 #include <linux/netfilter_ipv4/ipt_LOG.h>
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  28 MODULE_DESCRIPTION("iptables syslog logging module");
  29
  30 #if 0
  31 #define DEBUGP printk
  32 #else
  33 #define DEBUGP(format, args...)
  34 #endif
  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,
  42                         unsigned int iphoff)
  43 {
  44         struct iphdr _iph, *ih;
  45         unsigned int logflags;
  46
  47         if (info->type == NF_LOG_TYPE_LOG)
  48                 logflags = info->u.log.logflags;
  49         else
  50                 logflags = NF_LOG_MASK;
  51
  52         printk("TAG=%d ", skb->skb_tag);
  53
  54         ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
  55         if (ih == NULL) {
  56                 printk("TRUNCATED");
  57                 return;
  58         }
  59
  60         /* Important fields:
  61          * TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
  62         /* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
  63         printk("SRC=%u.%u.%u.%u DST=%u.%u.%u.%u ",
  64                NIPQUAD(ih->saddr), NIPQUAD(ih->daddr));
  65
  66         /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
  67         printk("LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
  68                ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
  69                ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
  70
  71         /* Max length: 6 "CE DF MF " */
  72         if (ntohs(ih->frag_off) & IP_CE)
  73                 printk("CE ");
  74         if (ntohs(ih->frag_off) & IP_DF)
  75                 printk("DF ");
  76         if (ntohs(ih->frag_off) & IP_MF)
  77                 printk("MF ");
  78
  79         /* Max length: 11 "FRAG:65535 " */
  80         if (ntohs(ih->frag_off) & IP_OFFSET)
  81                 printk("FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
  82
  83         if ((logflags & IPT_LOG_IPOPT)
  84             && ih->ihl * 4 > sizeof(struct iphdr)) {
  85                 unsigned char _opt[4 * 15 - sizeof(struct iphdr)], *op;
  86                 unsigned int i, optsize;
  87
  88                 optsize = ih->ihl * 4 - sizeof(struct iphdr);
  89                 op = skb_header_pointer(skb, iphoff+sizeof(_iph),
  90                                         optsize, _opt);
  91                 if (op == NULL) {
  92                         printk("TRUNCATED");
  93                         return;
  94                 }
  95
  96                 /* Max length: 127 "OPT (" 15*4*2chars ") " */
  97                 printk("OPT (");
  98                 for (i = 0; i < optsize; i++)
  99                         printk("%02X", op[i]);
 100                 printk(") ");
 101         }
 102
 103         switch (ih->protocol) {
 104         case IPPROTO_TCP: {
 105                 struct tcphdr _tcph, *th;
 106
 107                 /* Max length: 10 "PROTO=TCP " */
 108                 printk("PROTO=TCP ");
 109
 110                 if (ntohs(ih->frag_off) & IP_OFFSET)
 111                         break;
 112
 113                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 114                 th = skb_header_pointer(skb, iphoff + ih->ihl * 4,
 115                                         sizeof(_tcph), &_tcph);
 116                 if (th == NULL) {
 117                         printk("INCOMPLETE [%u bytes] ",
 118                                skb->len - iphoff - ih->ihl*4);
 119                         break;
 120                 }
 121
 122                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 123                 printk("SPT=%u DPT=%u ",
 124                        ntohs(th->source), ntohs(th->dest));
 125                 /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
 126                 if (logflags & IPT_LOG_TCPSEQ)
 127                         printk("SEQ=%u ACK=%u ",
 128                                ntohl(th->seq), ntohl(th->ack_seq));
 129                 /* Max length: 13 "WINDOW=65535 " */
 130                 printk("WINDOW=%u ", ntohs(th->window));
 131                 /* Max length: 9 "RES=0x3F " */
 132                 printk("RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
 133                 /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
 134                 if (th->cwr)
 135                         printk("CWR ");
 136                 if (th->ece)
 137                         printk("ECE ");
 138                 if (th->urg)
 139                         printk("URG ");
 140                 if (th->ack)
 141                         printk("ACK ");
 142                 if (th->psh)
 143                         printk("PSH ");
 144                 if (th->rst)
 145                         printk("RST ");
 146                 if (th->syn)
 147                         printk("SYN ");
 148                 if (th->fin)
 149                         printk("FIN ");
 150                 /* Max length: 11 "URGP=65535 " */
 151                 printk("URGP=%u ", ntohs(th->urg_ptr));
 152
 153                 if ((logflags & IPT_LOG_TCPOPT)
 154                     && th->doff * 4 > sizeof(struct tcphdr)) {
 155                         unsigned char _opt[4 * 15 - sizeof(struct tcphdr)];
 156                         unsigned char *op;
 157                         unsigned int i, optsize;
 158
 159                         optsize = th->doff * 4 - sizeof(struct tcphdr);
 160                         op = skb_header_pointer(skb,
 161                                                 iphoff+ih->ihl*4+sizeof(_tcph),
 162                                                 optsize, _opt);
 163                         if (op == NULL) {
 164                                 printk("TRUNCATED");
 165                                 return;
 166                         }
 167
 168                         /* Max length: 127 "OPT (" 15*4*2chars ") " */
 169                         printk("OPT (");
 170                         for (i = 0; i < optsize; i++)
 171                                 printk("%02X", op[i]);
 172                         printk(") ");
 173                 }
 174                 break;
 175         }
 176         case IPPROTO_UDP:
 177         case IPPROTO_UDPLITE: {
 178                 struct udphdr _udph, *uh;
 179
 180                 if (ih->protocol == IPPROTO_UDP)
 181                         /* Max length: 10 "PROTO=UDP "     */
 182                         printk("PROTO=UDP " );
 183                 else    /* Max length: 14 "PROTO=UDPLITE " */
 184                         printk("PROTO=UDPLITE ");
 185
 186                 if (ntohs(ih->frag_off) & IP_OFFSET)
 187                         break;
 188
 189                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 190                 uh = skb_header_pointer(skb, iphoff+ih->ihl*4,
 191                                         sizeof(_udph), &_udph);
 192                 if (uh == NULL) {
 193                         printk("INCOMPLETE [%u bytes] ",
 194                                skb->len - iphoff - ih->ihl*4);
 195                         break;
 196                 }
 197
 198                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 199                 printk("SPT=%u DPT=%u LEN=%u ",
 200                        ntohs(uh->source), ntohs(uh->dest),
 201                        ntohs(uh->len));
 202                 break;
 203         }
 204         case IPPROTO_ICMP: {
 205                 struct icmphdr _icmph, *ich;
 206                 static const size_t required_len[NR_ICMP_TYPES+1]
 207                         = { [ICMP_ECHOREPLY] = 4,
 208                             [ICMP_DEST_UNREACH]
 209                             = 8 + sizeof(struct iphdr),
 210                             [ICMP_SOURCE_QUENCH]
 211                             = 8 + sizeof(struct iphdr),
 212                             [ICMP_REDIRECT]
 213                             = 8 + sizeof(struct iphdr),
 214                             [ICMP_ECHO] = 4,
 215                             [ICMP_TIME_EXCEEDED]
 216                             = 8 + sizeof(struct iphdr),
 217                             [ICMP_PARAMETERPROB]
 218                             = 8 + sizeof(struct iphdr),
 219                             [ICMP_TIMESTAMP] = 20,
 220                             [ICMP_TIMESTAMPREPLY] = 20,
 221                             [ICMP_ADDRESS] = 12,
 222                             [ICMP_ADDRESSREPLY] = 12 };
 223
 224                 /* Max length: 11 "PROTO=ICMP " */
 225                 printk("PROTO=ICMP ");
 226
 227                 if (ntohs(ih->frag_off) & IP_OFFSET)
 228                         break;
 229
 230                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 231                 ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
 232                                          sizeof(_icmph), &_icmph);
 233                 if (ich == NULL) {
 234                         printk("INCOMPLETE [%u bytes] ",
 235                                skb->len - iphoff - ih->ihl*4);
 236                         break;
 237                 }
 238
 239                 /* Max length: 18 "TYPE=255 CODE=255 " */
 240                 printk("TYPE=%u CODE=%u ", ich->type, ich->code);
 241
 242                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 243                 if (ich->type <= NR_ICMP_TYPES
 244                     && required_len[ich->type]
 245                     && skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
 246                         printk("INCOMPLETE [%u bytes] ",
 247                                skb->len - iphoff - ih->ihl*4);
 248                         break;
 249                 }
 250
 251                 switch (ich->type) {
 252                 case ICMP_ECHOREPLY:
 253                 case ICMP_ECHO:
 254                         /* Max length: 19 "ID=65535 SEQ=65535 " */
 255                         printk("ID=%u SEQ=%u ",
 256                                ntohs(ich->un.echo.id),
 257                                ntohs(ich->un.echo.sequence));
 258                         break;
 259
 260                 case ICMP_PARAMETERPROB:
 261                         /* Max length: 14 "PARAMETER=255 " */
 262                         printk("PARAMETER=%u ",
 263                                ntohl(ich->un.gateway) >> 24);
 264                         break;
 265                 case ICMP_REDIRECT:
 266                         /* Max length: 24 "GATEWAY=255.255.255.255 " */
 267                         printk("GATEWAY=%u.%u.%u.%u ",
 268                                NIPQUAD(ich->un.gateway));
 269                         /* Fall through */
 270                 case ICMP_DEST_UNREACH:
 271                 case ICMP_SOURCE_QUENCH:
 272                 case ICMP_TIME_EXCEEDED:
 273                         /* Max length: 3+maxlen */
 274                         if (!iphoff) { /* Only recurse once. */
 275                                 printk("[");
 276                                 dump_packet(info, skb,
 277                                             iphoff + ih->ihl*4+sizeof(_icmph));
 278                                 printk("] ");
 279                         }
 280
 281                         /* Max length: 10 "MTU=65535 " */
 282                         if (ich->type == ICMP_DEST_UNREACH
 283                             && ich->code == ICMP_FRAG_NEEDED)
 284                                 printk("MTU=%u ", ntohs(ich->un.frag.mtu));
 285                 }
 286                 break;
 287         }
 288         /* Max Length */
 289         case IPPROTO_AH: {
 290                 struct ip_auth_hdr _ahdr, *ah;
 291
 292                 if (ntohs(ih->frag_off) & IP_OFFSET)
 293                         break;
 294
 295                 /* Max length: 9 "PROTO=AH " */
 296                 printk("PROTO=AH ");
 297
 298                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 299                 ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
 300                                         sizeof(_ahdr), &_ahdr);
 301                 if (ah == NULL) {
 302                         printk("INCOMPLETE [%u bytes] ",
 303                                skb->len - iphoff - ih->ihl*4);
 304                         break;
 305                 }
 306
 307                 /* Length: 15 "SPI=0xF1234567 " */
 308                 printk("SPI=0x%x ", ntohl(ah->spi));
 309                 break;
 310         }
 311         case IPPROTO_ESP: {
 312                 struct ip_esp_hdr _esph, *eh;
 313
 314                 /* Max length: 10 "PROTO=ESP " */
 315                 printk("PROTO=ESP ");
 316
 317                 if (ntohs(ih->frag_off) & IP_OFFSET)
 318                         break;
 319
 320                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 321                 eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
 322                                         sizeof(_esph), &_esph);
 323                 if (eh == NULL) {
 324                         printk("INCOMPLETE [%u bytes] ",
 325                                skb->len - iphoff - ih->ihl*4);
 326                         break;
 327                 }
 328
 329                 /* Length: 15 "SPI=0xF1234567 " */
 330                 printk("SPI=0x%x ", ntohl(eh->spi));
 331                 break;
 332         }
 333         /* Max length: 10 "PROTO 255 " */
 334         default:
 335                 printk("PROTO=%u ", ih->protocol);
 336         }
 337
 338         /* Max length: 15 "UID=4294967295 " */
 339         if ((logflags & IPT_LOG_UID) && !iphoff && skb->sk) {
 340                 read_lock_bh(&skb->sk->sk_callback_lock);
 341                 if (skb->sk->sk_socket && skb->sk->sk_socket->file)
 342                         printk("UID=%u ", skb->sk->sk_socket->file->f_uid);
 343                 read_unlock_bh(&skb->sk->sk_callback_lock);
 344         }
 345
 346         /* Proto    Max log string length */
 347         /* IP:      40+46+6+11+127 = 230 */
 348         /* TCP:     10+max(25,20+30+13+9+32+11+127) = 252 */
 349         /* UDP:     10+max(25,20) = 35 */
 350         /* UDPLITE: 14+max(25,20) = 39 */
 351         /* ICMP:    11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
 352         /* ESP:     10+max(25)+15 = 50 */
 353         /* AH:      9+max(25)+15 = 49 */
 354         /* unknown: 10 */
 355
 356         /* (ICMP allows recursion one level deep) */
 357         /* maxlen =  IP + ICMP +  IP + max(TCP,UDP,ICMP,unknown) */
 358         /* maxlen = 230+   91  + 230 + 252 = 803 */
 359 }
 360
 361 static struct nf_loginfo default_loginfo = {
 362         .type   = NF_LOG_TYPE_LOG,
 363         .u = {
 364                 .log = {
 365                         .level    = 0,
 366                         .logflags = NF_LOG_MASK,
 367                 },
 368         },
 369 };
 370
 371 static void
 372 ipt_log_packet(unsigned int pf,
 373                unsigned int hooknum,
 374                const struct sk_buff *skb,
 375                const struct net_device *in,
 376                const struct net_device *out,
 377                const struct nf_loginfo *loginfo,
 378                const char *prefix)
 379 {
 380         if (!loginfo)
 381                 loginfo = &default_loginfo;
 382
 383         spin_lock_bh(&log_lock);
 384         printk("<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
 385                prefix,
 386                in ? in->name : "",
 387                out ? out->name : "");
 388 #ifdef CONFIG_BRIDGE_NETFILTER
 389         if (skb->nf_bridge) {
 390                 struct net_device *physindev = skb->nf_bridge->physindev;
 391                 struct net_device *physoutdev = skb->nf_bridge->physoutdev;
 392
 393                 if (physindev && in != physindev)
 394                         printk("PHYSIN=%s ", physindev->name);
 395                 if (physoutdev && out != physoutdev)
 396                         printk("PHYSOUT=%s ", physoutdev->name);
 397         }
 398 #endif
 399
 400         if (in && !out) {
 401                 /* MAC logging for input chain only. */
 402                 printk("MAC=");
 403                 if (skb->dev && skb->dev->hard_header_len
 404                     && skb->mac.raw != (void*)skb->nh.iph) {
 405                         int i;
 406                         unsigned char *p = skb->mac.raw;
 407                         for (i = 0; i < skb->dev->hard_header_len; i++,p++)
 408                                 printk("%02x%c", *p,
 409                                        i==skb->dev->hard_header_len - 1
 410                                        ? ' ':':');
 411                 } else
 412                         printk(" ");
 413         }
 414
 415         dump_packet(loginfo, skb, 0);
 416         printk("\n");
 417         spin_unlock_bh(&log_lock);
 418 }
 419
 420 static unsigned int
 421 ipt_log_target(struct sk_buff **pskb,
 422                const struct net_device *in,
 423                const struct net_device *out,
 424                unsigned int hooknum,
 425                const struct xt_target *target,
 426                const void *targinfo)
 427 {
 428         const struct ipt_log_info *loginfo = targinfo;
 429         struct nf_loginfo li;
 430
 431         li.type = NF_LOG_TYPE_LOG;
 432         li.u.log.level = loginfo->level;
 433         li.u.log.logflags = loginfo->logflags;
 434
 435         ipt_log_packet(PF_INET, hooknum, *pskb, in, out, &li,
 436                        loginfo->prefix);
 437         return IPT_CONTINUE;
 438 }
 439
 440 static int ipt_log_checkentry(const char *tablename,
 441                               const void *e,
 442                               const struct xt_target *target,
 443                               void *targinfo,
 444                               unsigned int hook_mask)
 445 {
 446         const struct ipt_log_info *loginfo = targinfo;
 447
 448         if (loginfo->level >= 8) {
 449                 DEBUGP("LOG: level %u >= 8\n", loginfo->level);
 450                 return 0;
 451         }
 452         if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
 453                 DEBUGP("LOG: prefix term %i\n",
 454                        loginfo->prefix[sizeof(loginfo->prefix)-1]);
 455                 return 0;
 456         }
 457         return 1;
 458 }
 459
 460 static struct ipt_target ipt_log_reg = {
 461         .name           = "LOG",
 462         .target         = ipt_log_target,
 463         .targetsize     = sizeof(struct ipt_log_info),
 464         .checkentry     = ipt_log_checkentry,
 465         .me             = THIS_MODULE,
 466 };
 467
 468 static struct nf_logger ipt_log_logger ={
 469         .name           = "ipt_LOG",
 470         .logfn          = &ipt_log_packet,
 471         .me             = THIS_MODULE,
 472 };
 473
 474 static int __init ipt_log_init(void)
 475 {
 476         if (ipt_register_target(&ipt_log_reg))
 477                 return -EINVAL;
 478         if (nf_log_register(PF_INET, &ipt_log_logger) < 0) {
 479                 printk(KERN_WARNING "ipt_LOG: not logging via system console "
 480                        "since somebody else already registered for PF_INET\n");
 481                 /* we cannot make module load fail here, since otherwise
 482                  * iptables userspace would abort */
 483         }
 484
 485         return 0;
 486 }
 487
 488 static void __exit ipt_log_fini(void)
 489 {
 490         nf_log_unregister_logger(&ipt_log_logger);
 491         ipt_unregister_target(&ipt_log_reg);
 492 }
 493
 494 module_init(ipt_log_init);
 495 module_exit(ipt_log_fini);