net/ipv4/netfilter/nf_log_ipv4.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/if_arp.h>
  14 #include <linux/ip.h>
  15 #include <net/ipv6.h>
  16 #include <net/icmp.h>
  17 #include <net/udp.h>
  18 #include <net/tcp.h>
  19 #include <net/route.h>
  20
  21 #include <linux/netfilter.h>
  22 #include <linux/netfilter/xt_LOG.h>
  23 #include <net/netfilter/nf_log.h>
  24
  25 static struct nf_loginfo default_loginfo = {
  26         .type   = NF_LOG_TYPE_LOG,
  27         .u = {
  28                 .log = {
  29                         .level    = 5,
  30                         .logflags = NF_LOG_MASK,
  31                 },
  32         },
  33 };
  34
  35 /* One level of recursion won't kill us */
  36 static void dump_ipv4_packet(struct nf_log_buf *m,
  37                              const struct nf_loginfo *info,
  38                              const struct sk_buff *skb, unsigned int iphoff)
  39 {
  40         struct iphdr _iph;
  41         const struct iphdr *ih;
  42         unsigned int logflags;
  43
  44         if (info->type == NF_LOG_TYPE_LOG)
  45                 logflags = info->u.log.logflags;
  46         else
  47                 logflags = NF_LOG_MASK;
  48
  49         ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
  50         if (ih == NULL) {
  51                 nf_log_buf_add(m, "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         nf_log_buf_add(m, "SRC=%pI4 DST=%pI4 ", &ih->saddr, &ih->daddr);
  59
  60         /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
  61         nf_log_buf_add(m, "LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
  62                        ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
  63                        ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
  64
  65         /* Max length: 6 "CE DF MF " */
  66         if (ntohs(ih->frag_off) & IP_CE)
  67                 nf_log_buf_add(m, "CE ");
  68         if (ntohs(ih->frag_off) & IP_DF)
  69                 nf_log_buf_add(m, "DF ");
  70         if (ntohs(ih->frag_off) & IP_MF)
  71                 nf_log_buf_add(m, "MF ");
  72
  73         /* Max length: 11 "FRAG:65535 " */
  74         if (ntohs(ih->frag_off) & IP_OFFSET)
  75                 nf_log_buf_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
  76
  77         if ((logflags & XT_LOG_IPOPT) &&
  78             ih->ihl * 4 > sizeof(struct iphdr)) {
  79                 const unsigned char *op;
  80                 unsigned char _opt[4 * 15 - sizeof(struct iphdr)];
  81                 unsigned int i, optsize;
  82
  83                 optsize = ih->ihl * 4 - sizeof(struct iphdr);
  84                 op = skb_header_pointer(skb, iphoff+sizeof(_iph),
  85                                         optsize, _opt);
  86                 if (op == NULL) {
  87                         nf_log_buf_add(m, "TRUNCATED");
  88                         return;
  89                 }
  90
  91                 /* Max length: 127 "OPT (" 15*4*2chars ") " */
  92                 nf_log_buf_add(m, "OPT (");
  93                 for (i = 0; i < optsize; i++)
  94                         nf_log_buf_add(m, "%02X", op[i]);
  95                 nf_log_buf_add(m, ") ");
  96         }
  97
  98         switch (ih->protocol) {
  99         case IPPROTO_TCP:
 100                 if (nf_log_dump_tcp_header(m, skb, ih->protocol,
 101                                            ntohs(ih->frag_off) & IP_OFFSET,
 102                                            iphoff+ih->ihl*4, logflags))
 103                         return;
 104                 break;
 105         case IPPROTO_UDP:
 106         case IPPROTO_UDPLITE:
 107                 if (nf_log_dump_udp_header(m, skb, ih->protocol,
 108                                            ntohs(ih->frag_off) & IP_OFFSET,
 109                                            iphoff+ih->ihl*4))
 110                         return;
 111                 break;
 112         case IPPROTO_ICMP: {
 113                 struct icmphdr _icmph;
 114                 const struct icmphdr *ich;
 115                 static const size_t required_len[NR_ICMP_TYPES+1]
 116                         = { [ICMP_ECHOREPLY] = 4,
 117                             [ICMP_DEST_UNREACH]
 118                             = 8 + sizeof(struct iphdr),
 119                             [ICMP_SOURCE_QUENCH]
 120                             = 8 + sizeof(struct iphdr),
 121                             [ICMP_REDIRECT]
 122                             = 8 + sizeof(struct iphdr),
 123                             [ICMP_ECHO] = 4,
 124                             [ICMP_TIME_EXCEEDED]
 125                             = 8 + sizeof(struct iphdr),
 126                             [ICMP_PARAMETERPROB]
 127                             = 8 + sizeof(struct iphdr),
 128                             [ICMP_TIMESTAMP] = 20,
 129                             [ICMP_TIMESTAMPREPLY] = 20,
 130                             [ICMP_ADDRESS] = 12,
 131                             [ICMP_ADDRESSREPLY] = 12 };
 132
 133                 /* Max length: 11 "PROTO=ICMP " */
 134                 nf_log_buf_add(m, "PROTO=ICMP ");
 135
 136                 if (ntohs(ih->frag_off) & IP_OFFSET)
 137                         break;
 138
 139                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 140                 ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
 141                                          sizeof(_icmph), &_icmph);
 142                 if (ich == NULL) {
 143                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 144                                        skb->len - iphoff - ih->ihl*4);
 145                         break;
 146                 }
 147
 148                 /* Max length: 18 "TYPE=255 CODE=255 " */
 149                 nf_log_buf_add(m, "TYPE=%u CODE=%u ", ich->type, ich->code);
 150
 151                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 152                 if (ich->type <= NR_ICMP_TYPES &&
 153                     required_len[ich->type] &&
 154                     skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
 155                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 156                                        skb->len - iphoff - ih->ihl*4);
 157                         break;
 158                 }
 159
 160                 switch (ich->type) {
 161                 case ICMP_ECHOREPLY:
 162                 case ICMP_ECHO:
 163                         /* Max length: 19 "ID=65535 SEQ=65535 " */
 164                         nf_log_buf_add(m, "ID=%u SEQ=%u ",
 165                                        ntohs(ich->un.echo.id),
 166                                        ntohs(ich->un.echo.sequence));
 167                         break;
 168
 169                 case ICMP_PARAMETERPROB:
 170                         /* Max length: 14 "PARAMETER=255 " */
 171                         nf_log_buf_add(m, "PARAMETER=%u ",
 172                                        ntohl(ich->un.gateway) >> 24);
 173                         break;
 174                 case ICMP_REDIRECT:
 175                         /* Max length: 24 "GATEWAY=255.255.255.255 " */
 176                         nf_log_buf_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
 177                         /* Fall through */
 178                 case ICMP_DEST_UNREACH:
 179                 case ICMP_SOURCE_QUENCH:
 180                 case ICMP_TIME_EXCEEDED:
 181                         /* Max length: 3+maxlen */
 182                         if (!iphoff) { /* Only recurse once. */
 183                                 nf_log_buf_add(m, "[");
 184                                 dump_ipv4_packet(m, info, skb,
 185                                             iphoff + ih->ihl*4+sizeof(_icmph));
 186                                 nf_log_buf_add(m, "] ");
 187                         }
 188
 189                         /* Max length: 10 "MTU=65535 " */
 190                         if (ich->type == ICMP_DEST_UNREACH &&
 191                             ich->code == ICMP_FRAG_NEEDED) {
 192                                 nf_log_buf_add(m, "MTU=%u ",
 193                                                ntohs(ich->un.frag.mtu));
 194                         }
 195                 }
 196                 break;
 197         }
 198         /* Max Length */
 199         case IPPROTO_AH: {
 200                 struct ip_auth_hdr _ahdr;
 201                 const struct ip_auth_hdr *ah;
 202
 203                 if (ntohs(ih->frag_off) & IP_OFFSET)
 204                         break;
 205
 206                 /* Max length: 9 "PROTO=AH " */
 207                 nf_log_buf_add(m, "PROTO=AH ");
 208
 209                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 210                 ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
 211                                         sizeof(_ahdr), &_ahdr);
 212                 if (ah == NULL) {
 213                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 214                                        skb->len - iphoff - ih->ihl*4);
 215                         break;
 216                 }
 217
 218                 /* Length: 15 "SPI=0xF1234567 " */
 219                 nf_log_buf_add(m, "SPI=0x%x ", ntohl(ah->spi));
 220                 break;
 221         }
 222         case IPPROTO_ESP: {
 223                 struct ip_esp_hdr _esph;
 224                 const struct ip_esp_hdr *eh;
 225
 226                 /* Max length: 10 "PROTO=ESP " */
 227                 nf_log_buf_add(m, "PROTO=ESP ");
 228
 229                 if (ntohs(ih->frag_off) & IP_OFFSET)
 230                         break;
 231
 232                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 233                 eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
 234                                         sizeof(_esph), &_esph);
 235                 if (eh == NULL) {
 236                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 237                                        skb->len - iphoff - ih->ihl*4);
 238                         break;
 239                 }
 240
 241                 /* Length: 15 "SPI=0xF1234567 " */
 242                 nf_log_buf_add(m, "SPI=0x%x ", ntohl(eh->spi));
 243                 break;
 244         }
 245         /* Max length: 10 "PROTO 255 " */
 246         default:
 247                 nf_log_buf_add(m, "PROTO=%u ", ih->protocol);
 248         }
 249
 250         /* Max length: 15 "UID=4294967295 " */
 251         if ((logflags & XT_LOG_UID) && !iphoff)
 252                 nf_log_dump_sk_uid_gid(m, skb->sk);
 253
 254         /* Max length: 16 "MARK=0xFFFFFFFF " */
 255         if (!iphoff && skb->mark)
 256                 nf_log_buf_add(m, "MARK=0x%x ", skb->mark);
 257
 258         /* Proto    Max log string length */
 259         /* IP:      40+46+6+11+127 = 230 */
 260         /* TCP:     10+max(25,20+30+13+9+32+11+127) = 252 */
 261         /* UDP:     10+max(25,20) = 35 */
 262         /* UDPLITE: 14+max(25,20) = 39 */
 263         /* ICMP:    11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
 264         /* ESP:     10+max(25)+15 = 50 */
 265         /* AH:      9+max(25)+15 = 49 */
 266         /* unknown: 10 */
 267
 268         /* (ICMP allows recursion one level deep) */
 269         /* maxlen =  IP + ICMP +  IP + max(TCP,UDP,ICMP,unknown) */
 270         /* maxlen = 230+   91  + 230 + 252 = 803 */
 271 }
 272
 273 static void dump_ipv4_mac_header(struct nf_log_buf *m,
 274                             const struct nf_loginfo *info,
 275                             const struct sk_buff *skb)
 276 {
 277         struct net_device *dev = skb->dev;
 278         unsigned int logflags = 0;
 279
 280         if (info->type == NF_LOG_TYPE_LOG)
 281                 logflags = info->u.log.logflags;
 282
 283         if (!(logflags & XT_LOG_MACDECODE))
 284                 goto fallback;
 285
 286         switch (dev->type) {
 287         case ARPHRD_ETHER:
 288                 nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
 289                                eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
 290                                ntohs(eth_hdr(skb)->h_proto));
 291                 return;
 292         default:
 293                 break;
 294         }
 295
 296 fallback:
 297         nf_log_buf_add(m, "MAC=");
 298         if (dev->hard_header_len &&
 299             skb->mac_header != skb->network_header) {
 300                 const unsigned char *p = skb_mac_header(skb);
 301                 unsigned int i;
 302
 303                 nf_log_buf_add(m, "%02x", *p++);
 304                 for (i = 1; i < dev->hard_header_len; i++, p++)
 305                         nf_log_buf_add(m, ":%02x", *p);
 306         }
 307         nf_log_buf_add(m, " ");
 308 }
 309
 310 static void nf_log_ip_packet(struct net *net, u_int8_t pf,
 311                              unsigned int hooknum, const struct sk_buff *skb,
 312                              const struct net_device *in,
 313                              const struct net_device *out,
 314                              const struct nf_loginfo *loginfo,
 315                              const char *prefix)
 316 {
 317         struct nf_log_buf *m;
 318
 319         /* FIXME: Disabled from containers until syslog ns is supported */
 320         if (!net_eq(net, &init_net))
 321                 return;
 322
 323         m = nf_log_buf_open();
 324
 325         if (!loginfo)
 326                 loginfo = &default_loginfo;
 327
 328         nf_log_dump_packet_common(m, pf, hooknum, skb, in,
 329                                   out, loginfo, prefix);
 330
 331         if (in != NULL)
 332                 dump_ipv4_mac_header(m, loginfo, skb);
 333
 334         dump_ipv4_packet(m, loginfo, skb, 0);
 335
 336         nf_log_buf_close(m);
 337 }
 338
 339 static struct nf_logger nf_ip_logger __read_mostly = {
 340         .name           = "nf_log_ipv4",
 341         .type           = NF_LOG_TYPE_LOG,
 342         .logfn          = nf_log_ip_packet,
 343         .me             = THIS_MODULE,
 344 };
 345
 346 static int __net_init nf_log_ipv4_net_init(struct net *net)
 347 {
 348         nf_log_set(net, NFPROTO_IPV4, &nf_ip_logger);
 349         return 0;
 350 }
 351
 352 static void __net_exit nf_log_ipv4_net_exit(struct net *net)
 353 {
 354         nf_log_unset(net, &nf_ip_logger);
 355 }
 356
 357 static struct pernet_operations nf_log_ipv4_net_ops = {
 358         .init = nf_log_ipv4_net_init,
 359         .exit = nf_log_ipv4_net_exit,
 360 };
 361
 362 static int __init nf_log_ipv4_init(void)
 363 {
 364         int ret;
 365
 366         ret = register_pernet_subsys(&nf_log_ipv4_net_ops);
 367         if (ret < 0)
 368                 return ret;
 369
 370         ret = nf_log_register(NFPROTO_IPV4, &nf_ip_logger);
 371         if (ret < 0) {
 372                 pr_err("failed to register logger\n");
 373                 goto err1;
 374         }
 375
 376         return 0;
 377
 378 err1:
 379         unregister_pernet_subsys(&nf_log_ipv4_net_ops);
 380         return ret;
 381 }
 382
 383 static void __exit nf_log_ipv4_exit(void)
 384 {
 385         unregister_pernet_subsys(&nf_log_ipv4_net_ops);
 386         nf_log_unregister(&nf_ip_logger);
 387 }
 388
 389 module_init(nf_log_ipv4_init);
 390 module_exit(nf_log_ipv4_exit);
 391
 392 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
 393 MODULE_DESCRIPTION("Netfilter IPv4 packet logging");
 394 MODULE_LICENSE("GPL");
 395 MODULE_ALIAS_NF_LOGGER(AF_INET, 0);