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 static unsigned int nflog = 1;
  31 module_param(nflog, int, 0400);
  32 MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
  33
  34 #if 0
  35 #define DEBUGP printk
  36 #else
  37 #define DEBUGP(format, args...)
  38 #endif
  39
  40 /* Use lock to serialize, so printks don't overlap */
  41 static DEFINE_SPINLOCK(log_lock);
  42
  43 /* One level of recursion won't kill us */
  44 static void dump_packet(const struct ipt_log_info *info,
  45                         const struct sk_buff *skb,
  46                         unsigned int iphoff)
  47 {
  48         struct iphdr _iph, *ih;
  49
  50         ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
  51         if (ih == NULL) {
  52                 printk("TRUNCATED");
  53                 return;
  54         }
  55
  56         /* Important fields:
  57          * TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
  58         /* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
  59         printk("SRC=%u.%u.%u.%u DST=%u.%u.%u.%u ",
  60                NIPQUAD(ih->saddr), NIPQUAD(ih->daddr));
  61
  62         /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
  63         printk("LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
  64                ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
  65                ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
  66
  67         /* Max length: 6 "CE DF MF " */
  68         if (ntohs(ih->frag_off) & IP_CE)
  69                 printk("CE ");
  70         if (ntohs(ih->frag_off) & IP_DF)
  71                 printk("DF ");
  72         if (ntohs(ih->frag_off) & IP_MF)
  73                 printk("MF ");
  74
  75         /* Max length: 11 "FRAG:65535 " */
  76         if (ntohs(ih->frag_off) & IP_OFFSET)
  77                 printk("FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
  78
  79         if ((info->logflags & IPT_LOG_IPOPT)
  80             && ih->ihl * 4 > sizeof(struct iphdr)) {
  81                 unsigned char _opt[4 * 15 - sizeof(struct iphdr)], *op;
  82                 unsigned int i, optsize;
  83
  84                 optsize = ih->ihl * 4 - sizeof(struct iphdr);
  85                 op = skb_header_pointer(skb, iphoff+sizeof(_iph),
  86                                         optsize, _opt);
  87                 if (op == NULL) {
  88                         printk("TRUNCATED");
  89                         return;
  90                 }
  91
  92                 /* Max length: 127 "OPT (" 15*4*2chars ") " */
  93                 printk("OPT (");
  94                 for (i = 0; i < optsize; i++)
  95                         printk("%02X", op[i]);
  96                 printk(") ");
  97         }
  98
  99         switch (ih->protocol) {
 100         case IPPROTO_TCP: {
 101                 struct tcphdr _tcph, *th;
 102
 103                 /* Max length: 10 "PROTO=TCP " */
 104                 printk("PROTO=TCP ");
 105
 106                 if (ntohs(ih->frag_off) & IP_OFFSET)
 107                         break;
 108
 109                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 110                 th = skb_header_pointer(skb, iphoff + ih->ihl * 4,
 111                                         sizeof(_tcph), &_tcph);
 112                 if (th == NULL) {
 113                         printk("INCOMPLETE [%u bytes] ",
 114                                skb->len - iphoff - ih->ihl*4);
 115                         break;
 116                 }
 117
 118                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 119                 printk("SPT=%u DPT=%u ",
 120                        ntohs(th->source), ntohs(th->dest));
 121                 /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
 122                 if (info->logflags & IPT_LOG_TCPSEQ)
 123                         printk("SEQ=%u ACK=%u ",
 124                                ntohl(th->seq), ntohl(th->ack_seq));
 125                 /* Max length: 13 "WINDOW=65535 " */
 126                 printk("WINDOW=%u ", ntohs(th->window));
 127                 /* Max length: 9 "RES=0x3F " */
 128                 printk("RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
 129                 /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
 130                 if (th->cwr)
 131                         printk("CWR ");
 132                 if (th->ece)
 133                         printk("ECE ");
 134                 if (th->urg)
 135                         printk("URG ");
 136                 if (th->ack)
 137                         printk("ACK ");
 138                 if (th->psh)
 139                         printk("PSH ");
 140                 if (th->rst)
 141                         printk("RST ");
 142                 if (th->syn)
 143                         printk("SYN ");
 144                 if (th->fin)
 145                         printk("FIN ");
 146                 /* Max length: 11 "URGP=65535 " */
 147                 printk("URGP=%u ", ntohs(th->urg_ptr));
 148
 149                 if ((info->logflags & IPT_LOG_TCPOPT)
 150                     && th->doff * 4 > sizeof(struct tcphdr)) {
 151                         unsigned char _opt[4 * 15 - sizeof(struct tcphdr)];
 152                         unsigned char *op;
 153                         unsigned int i, optsize;
 154
 155                         optsize = th->doff * 4 - sizeof(struct tcphdr);
 156                         op = skb_header_pointer(skb,
 157                                                 iphoff+ih->ihl*4+sizeof(_tcph),
 158                                                 optsize, _opt);
 159                         if (op == NULL) {
 160                                 printk("TRUNCATED");
 161                                 return;
 162                         }
 163
 164                         /* Max length: 127 "OPT (" 15*4*2chars ") " */
 165                         printk("OPT (");
 166                         for (i = 0; i < optsize; i++)
 167                                 printk("%02X", op[i]);
 168                         printk(") ");
 169                 }
 170                 break;
 171         }
 172         case IPPROTO_UDP: {
 173                 struct udphdr _udph, *uh;
 174
 175                 /* Max length: 10 "PROTO=UDP " */
 176                 printk("PROTO=UDP ");
 177
 178                 if (ntohs(ih->frag_off) & IP_OFFSET)
 179                         break;
 180
 181                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 182                 uh = skb_header_pointer(skb, iphoff+ih->ihl*4,
 183                                         sizeof(_udph), &_udph);
 184                 if (uh == NULL) {
 185                         printk("INCOMPLETE [%u bytes] ",
 186                                skb->len - iphoff - ih->ihl*4);
 187                         break;
 188                 }
 189
 190                 /* Max length: 20 "SPT=65535 DPT=65535 " */
 191                 printk("SPT=%u DPT=%u LEN=%u ",
 192                        ntohs(uh->source), ntohs(uh->dest),
 193                        ntohs(uh->len));
 194                 break;
 195         }
 196         case IPPROTO_ICMP: {
 197                 struct icmphdr _icmph, *ich;
 198                 static size_t required_len[NR_ICMP_TYPES+1]
 199                         = { [ICMP_ECHOREPLY] = 4,
 200                             [ICMP_DEST_UNREACH]
 201                             = 8 + sizeof(struct iphdr),
 202                             [ICMP_SOURCE_QUENCH]
 203                             = 8 + sizeof(struct iphdr),
 204                             [ICMP_REDIRECT]
 205                             = 8 + sizeof(struct iphdr),
 206                             [ICMP_ECHO] = 4,
 207                             [ICMP_TIME_EXCEEDED]
 208                             = 8 + sizeof(struct iphdr),
 209                             [ICMP_PARAMETERPROB]
 210                             = 8 + sizeof(struct iphdr),
 211                             [ICMP_TIMESTAMP] = 20,
 212                             [ICMP_TIMESTAMPREPLY] = 20,
 213                             [ICMP_ADDRESS] = 12,
 214                             [ICMP_ADDRESSREPLY] = 12 };
 215
 216                 /* Max length: 11 "PROTO=ICMP " */
 217                 printk("PROTO=ICMP ");
 218
 219                 if (ntohs(ih->frag_off) & IP_OFFSET)
 220                         break;
 221
 222                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 223                 ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
 224                                          sizeof(_icmph), &_icmph);
 225                 if (ich == NULL) {
 226                         printk("INCOMPLETE [%u bytes] ",
 227                                skb->len - iphoff - ih->ihl*4);
 228                         break;
 229                 }
 230
 231                 /* Max length: 18 "TYPE=255 CODE=255 " */
 232                 printk("TYPE=%u CODE=%u ", ich->type, ich->code);
 233
 234                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 235                 if (ich->type <= NR_ICMP_TYPES
 236                     && required_len[ich->type]
 237                     && skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
 238                         printk("INCOMPLETE [%u bytes] ",
 239                                skb->len - iphoff - ih->ihl*4);
 240                         break;
 241                 }
 242
 243                 switch (ich->type) {
 244                 case ICMP_ECHOREPLY:
 245                 case ICMP_ECHO:
 246                         /* Max length: 19 "ID=65535 SEQ=65535 " */
 247                         printk("ID=%u SEQ=%u ",
 248                                ntohs(ich->un.echo.id),
 249                                ntohs(ich->un.echo.sequence));
 250                         break;
 251
 252                 case ICMP_PARAMETERPROB:
 253                         /* Max length: 14 "PARAMETER=255 " */
 254                         printk("PARAMETER=%u ",
 255                                ntohl(ich->un.gateway) >> 24);
 256                         break;
 257                 case ICMP_REDIRECT:
 258                         /* Max length: 24 "GATEWAY=255.255.255.255 " */
 259                         printk("GATEWAY=%u.%u.%u.%u ",
 260                                NIPQUAD(ich->un.gateway));
 261                         /* Fall through */
 262                 case ICMP_DEST_UNREACH:
 263                 case ICMP_SOURCE_QUENCH:
 264                 case ICMP_TIME_EXCEEDED:
 265                         /* Max length: 3+maxlen */
 266                         if (!iphoff) { /* Only recurse once. */
 267                                 printk("[");
 268                                 dump_packet(info, skb,
 269                                             iphoff + ih->ihl*4+sizeof(_icmph));
 270                                 printk("] ");
 271                         }
 272
 273                         /* Max length: 10 "MTU=65535 " */
 274                         if (ich->type == ICMP_DEST_UNREACH
 275                             && ich->code == ICMP_FRAG_NEEDED)
 276                                 printk("MTU=%u ", ntohs(ich->un.frag.mtu));
 277                 }
 278                 break;
 279         }
 280         /* Max Length */
 281         case IPPROTO_AH: {
 282                 struct ip_auth_hdr _ahdr, *ah;
 283
 284                 if (ntohs(ih->frag_off) & IP_OFFSET)
 285                         break;
 286
 287                 /* Max length: 9 "PROTO=AH " */
 288                 printk("PROTO=AH ");
 289
 290                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 291                 ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
 292                                         sizeof(_ahdr), &_ahdr);
 293                 if (ah == NULL) {
 294                         printk("INCOMPLETE [%u bytes] ",
 295                                skb->len - iphoff - ih->ihl*4);
 296                         break;
 297                 }
 298
 299                 /* Length: 15 "SPI=0xF1234567 " */
 300                 printk("SPI=0x%x ", ntohl(ah->spi));
 301                 break;
 302         }
 303         case IPPROTO_ESP: {
 304                 struct ip_esp_hdr _esph, *eh;
 305
 306                 /* Max length: 10 "PROTO=ESP " */
 307                 printk("PROTO=ESP ");
 308
 309                 if (ntohs(ih->frag_off) & IP_OFFSET)
 310                         break;
 311
 312                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 313                 eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
 314                                         sizeof(_esph), &_esph);
 315                 if (eh == NULL) {
 316                         printk("INCOMPLETE [%u bytes] ",
 317                                skb->len - iphoff - ih->ihl*4);
 318                         break;
 319                 }
 320
 321                 /* Length: 15 "SPI=0xF1234567 " */
 322                 printk("SPI=0x%x ", ntohl(eh->spi));
 323                 break;
 324         }
 325         /* Max length: 10 "PROTO 255 " */
 326         default:
 327                 printk("PROTO=%u ", ih->protocol);
 328         }
 329
 330         /* Max length: 15 "UID=4294967295 " */
 331         if ((info->logflags & IPT_LOG_UID) && !iphoff && skb->sk) {
 332                 read_lock_bh(&skb->sk->sk_callback_lock);
 333                 if (skb->sk->sk_socket && skb->sk->sk_socket->file)
 334                         printk("UID=%u ", skb->sk->sk_socket->file->f_uid);
 335                 read_unlock_bh(&skb->sk->sk_callback_lock);
 336         }
 337
 338         /* Proto    Max log string length */
 339         /* IP:      40+46+6+11+127 = 230 */
 340         /* TCP:     10+max(25,20+30+13+9+32+11+127) = 252 */
 341         /* UDP:     10+max(25,20) = 35 */
 342         /* ICMP:    11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
 343         /* ESP:     10+max(25)+15 = 50 */
 344         /* AH:      9+max(25)+15 = 49 */
 345         /* unknown: 10 */
 346
 347         /* (ICMP allows recursion one level deep) */
 348         /* maxlen =  IP + ICMP +  IP + max(TCP,UDP,ICMP,unknown) */
 349         /* maxlen = 230+   91  + 230 + 252 = 803 */
 350 }
 351
 352 static void
 353 ipt_log_packet(unsigned int hooknum,
 354                const struct sk_buff *skb,
 355                const struct net_device *in,
 356                const struct net_device *out,
 357                const struct ipt_log_info *loginfo,
 358                const char *level_string,
 359                const char *prefix)
 360 {
 361         spin_lock_bh(&log_lock);
 362         printk(level_string);
 363         printk("%sIN=%s OUT=%s ",
 364                prefix == NULL ? loginfo->prefix : prefix,
 365                in ? in->name : "",
 366                out ? out->name : "");
 367 #ifdef CONFIG_BRIDGE_NETFILTER
 368         if (skb->nf_bridge) {
 369                 struct net_device *physindev = skb->nf_bridge->physindev;
 370                 struct net_device *physoutdev = skb->nf_bridge->physoutdev;
 371
 372                 if (physindev && in != physindev)
 373                         printk("PHYSIN=%s ", physindev->name);
 374                 if (physoutdev && out != physoutdev)
 375                         printk("PHYSOUT=%s ", physoutdev->name);
 376         }
 377 #endif
 378
 379         if (in && !out) {
 380                 /* MAC logging for input chain only. */
 381                 printk("MAC=");
 382                 if (skb->dev && skb->dev->hard_header_len
 383                     && skb->mac.raw != (void*)skb->nh.iph) {
 384                         int i;
 385                         unsigned char *p = skb->mac.raw;
 386                         for (i = 0; i < skb->dev->hard_header_len; i++,p++)
 387                                 printk("%02x%c", *p,
 388                                        i==skb->dev->hard_header_len - 1
 389                                        ? ' ':':');
 390                 } else
 391                         printk(" ");
 392         }
 393
 394         dump_packet(loginfo, skb, 0);
 395         printk("\n");
 396         spin_unlock_bh(&log_lock);
 397 }
 398
 399 static unsigned int
 400 ipt_log_target(struct sk_buff **pskb,
 401                const struct net_device *in,
 402                const struct net_device *out,
 403                unsigned int hooknum,
 404                const void *targinfo,
 405                void *userinfo)
 406 {
 407         const struct ipt_log_info *loginfo = targinfo;
 408         char level_string[4] = "< >";
 409
 410         level_string[1] = '0' + (loginfo->level % 8);
 411         ipt_log_packet(hooknum, *pskb, in, out, loginfo, level_string, NULL);
 412
 413         return IPT_CONTINUE;
 414 }
 415
 416 static void
 417 ipt_logfn(unsigned int hooknum,
 418           const struct sk_buff *skb,
 419           const struct net_device *in,
 420           const struct net_device *out,
 421           const char *prefix)
 422 {
 423         struct ipt_log_info loginfo = {
 424                 .level = 0,
 425                 .logflags = IPT_LOG_MASK,
 426                 .prefix = ""
 427         };
 428
 429         ipt_log_packet(hooknum, skb, in, out, &loginfo, KERN_WARNING, prefix);
 430 }
 431
 432 static int ipt_log_checkentry(const char *tablename,
 433                               const struct ipt_entry *e,
 434                               void *targinfo,
 435                               unsigned int targinfosize,
 436                               unsigned int hook_mask)
 437 {
 438         const struct ipt_log_info *loginfo = targinfo;
 439
 440         if (targinfosize != IPT_ALIGN(sizeof(struct ipt_log_info))) {
 441                 DEBUGP("LOG: targinfosize %u != %u\n",
 442                        targinfosize, IPT_ALIGN(sizeof(struct ipt_log_info)));
 443                 return 0;
 444         }
 445
 446         if (loginfo->level >= 8) {
 447                 DEBUGP("LOG: level %u >= 8\n", loginfo->level);
 448                 return 0;
 449         }
 450
 451         if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
 452                 DEBUGP("LOG: prefix term %i\n",
 453                        loginfo->prefix[sizeof(loginfo->prefix)-1]);
 454                 return 0;
 455         }
 456
 457         return 1;
 458 }
 459
 460 static struct ipt_target ipt_log_reg = {
 461         .name           = "LOG",
 462         .target         = ipt_log_target,
 463         .checkentry     = ipt_log_checkentry,
 464         .me             = THIS_MODULE,
 465 };
 466
 467 static int __init init(void)
 468 {
 469         if (ipt_register_target(&ipt_log_reg))
 470                 return -EINVAL;
 471         if (nflog)
 472                 nf_log_register(PF_INET, &ipt_logfn);
 473
 474         return 0;
 475 }
 476
 477 static void __exit fini(void)
 478 {
 479         if (nflog)
 480                 nf_log_unregister(PF_INET, &ipt_logfn);
 481         ipt_unregister_target(&ipt_log_reg);
 482 }
 483
 484 module_init(init);
 485 module_exit(fini);