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