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