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
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/if_arp.h>
  16 #include <linux/ip.h>
  17 #include <net/ipv6.h>
  18 #include <net/icmp.h>
  19 #include <net/udp.h>
  20 #include <net/tcp.h>
  21 #include <net/route.h>
  22
  23 #include <linux/netfilter.h>
  24 #include <linux/netfilter/xt_LOG.h>
  25 #include <net/netfilter/nf_log.h>
  26
  27 static struct nf_loginfo default_loginfo = {
  28         .type   = NF_LOG_TYPE_LOG,
  29         .u = {
  30                 .log = {
  31                         .level    = LOGLEVEL_NOTICE,
  32                         .logflags = NF_LOG_MASK,
  33                 },
  34         },
  35 };
  36
  37 /* One level of recursion won't kill us */
  38 static void dump_ipv4_packet(struct nf_log_buf *m,
  39                              const struct nf_loginfo *info,
  40                              const struct sk_buff *skb, unsigned int iphoff)
  41 {
  42         struct iphdr _iph;
  43         const struct iphdr *ih;
  44         unsigned int logflags;
  45
  46         if (info->type == NF_LOG_TYPE_LOG)
  47                 logflags = info->u.log.logflags;
  48         else
  49                 logflags = NF_LOG_MASK;
  50
  51         ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
  52         if (ih == NULL) {
  53                 nf_log_buf_add(m, "TRUNCATED");
  54                 return;
  55         }
  56
  57         /* Important fields:
  58          * TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
  59         /* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
  60         nf_log_buf_add(m, "SRC=%pI4 DST=%pI4 ", &ih->saddr, &ih->daddr);
  61
  62         /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
  63         nf_log_buf_add(m, "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                 nf_log_buf_add(m, "CE ");
  70         if (ntohs(ih->frag_off) & IP_DF)
  71                 nf_log_buf_add(m, "DF ");
  72         if (ntohs(ih->frag_off) & IP_MF)
  73                 nf_log_buf_add(m, "MF ");
  74
  75         /* Max length: 11 "FRAG:65535 " */
  76         if (ntohs(ih->frag_off) & IP_OFFSET)
  77                 nf_log_buf_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
  78
  79         if ((logflags & XT_LOG_IPOPT) &&
  80             ih->ihl * 4 > sizeof(struct iphdr)) {
  81                 const unsigned char *op;
  82                 unsigned char _opt[4 * 15 - sizeof(struct iphdr)];
  83                 unsigned int i, optsize;
  84
  85                 optsize = ih->ihl * 4 - sizeof(struct iphdr);
  86                 op = skb_header_pointer(skb, iphoff+sizeof(_iph),
  87                                         optsize, _opt);
  88                 if (op == NULL) {
  89                         nf_log_buf_add(m, "TRUNCATED");
  90                         return;
  91                 }
  92
  93                 /* Max length: 127 "OPT (" 15*4*2chars ") " */
  94                 nf_log_buf_add(m, "OPT (");
  95                 for (i = 0; i < optsize; i++)
  96                         nf_log_buf_add(m, "%02X", op[i]);
  97                 nf_log_buf_add(m, ") ");
  98         }
  99
 100         switch (ih->protocol) {
 101         case IPPROTO_TCP:
 102                 if (nf_log_dump_tcp_header(m, skb, ih->protocol,
 103                                            ntohs(ih->frag_off) & IP_OFFSET,
 104                                            iphoff+ih->ihl*4, logflags))
 105                         return;
 106                 break;
 107         case IPPROTO_UDP:
 108         case IPPROTO_UDPLITE:
 109                 if (nf_log_dump_udp_header(m, skb, ih->protocol,
 110                                            ntohs(ih->frag_off) & IP_OFFSET,
 111                                            iphoff+ih->ihl*4))
 112                         return;
 113                 break;
 114         case IPPROTO_ICMP: {
 115                 struct icmphdr _icmph;
 116                 const struct icmphdr *ich;
 117                 static const size_t required_len[NR_ICMP_TYPES+1]
 118                         = { [ICMP_ECHOREPLY] = 4,
 119                             [ICMP_DEST_UNREACH]
 120                             = 8 + sizeof(struct iphdr),
 121                             [ICMP_SOURCE_QUENCH]
 122                             = 8 + sizeof(struct iphdr),
 123                             [ICMP_REDIRECT]
 124                             = 8 + sizeof(struct iphdr),
 125                             [ICMP_ECHO] = 4,
 126                             [ICMP_TIME_EXCEEDED]
 127                             = 8 + sizeof(struct iphdr),
 128                             [ICMP_PARAMETERPROB]
 129                             = 8 + sizeof(struct iphdr),
 130                             [ICMP_TIMESTAMP] = 20,
 131                             [ICMP_TIMESTAMPREPLY] = 20,
 132                             [ICMP_ADDRESS] = 12,
 133                             [ICMP_ADDRESSREPLY] = 12 };
 134
 135                 /* Max length: 11 "PROTO=ICMP " */
 136                 nf_log_buf_add(m, "PROTO=ICMP ");
 137
 138                 if (ntohs(ih->frag_off) & IP_OFFSET)
 139                         break;
 140
 141                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 142                 ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
 143                                          sizeof(_icmph), &_icmph);
 144                 if (ich == NULL) {
 145                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 146                                        skb->len - iphoff - ih->ihl*4);
 147                         break;
 148                 }
 149
 150                 /* Max length: 18 "TYPE=255 CODE=255 " */
 151                 nf_log_buf_add(m, "TYPE=%u CODE=%u ", ich->type, ich->code);
 152
 153                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 154                 if (ich->type <= NR_ICMP_TYPES &&
 155                     required_len[ich->type] &&
 156                     skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
 157                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 158                                        skb->len - iphoff - ih->ihl*4);
 159                         break;
 160                 }
 161
 162                 switch (ich->type) {
 163                 case ICMP_ECHOREPLY:
 164                 case ICMP_ECHO:
 165                         /* Max length: 19 "ID=65535 SEQ=65535 " */
 166                         nf_log_buf_add(m, "ID=%u SEQ=%u ",
 167                                        ntohs(ich->un.echo.id),
 168                                        ntohs(ich->un.echo.sequence));
 169                         break;
 170
 171                 case ICMP_PARAMETERPROB:
 172                         /* Max length: 14 "PARAMETER=255 " */
 173                         nf_log_buf_add(m, "PARAMETER=%u ",
 174                                        ntohl(ich->un.gateway) >> 24);
 175                         break;
 176                 case ICMP_REDIRECT:
 177                         /* Max length: 24 "GATEWAY=255.255.255.255 " */
 178                         nf_log_buf_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
 179                         /* Fall through */
 180                 case ICMP_DEST_UNREACH:
 181                 case ICMP_SOURCE_QUENCH:
 182                 case ICMP_TIME_EXCEEDED:
 183                         /* Max length: 3+maxlen */
 184                         if (!iphoff) { /* Only recurse once. */
 185                                 nf_log_buf_add(m, "[");
 186                                 dump_ipv4_packet(m, info, skb,
 187                                             iphoff + ih->ihl*4+sizeof(_icmph));
 188                                 nf_log_buf_add(m, "] ");
 189                         }
 190
 191                         /* Max length: 10 "MTU=65535 " */
 192                         if (ich->type == ICMP_DEST_UNREACH &&
 193                             ich->code == ICMP_FRAG_NEEDED) {
 194                                 nf_log_buf_add(m, "MTU=%u ",
 195                                                ntohs(ich->un.frag.mtu));
 196                         }
 197                 }
 198                 break;
 199         }
 200         /* Max Length */
 201         case IPPROTO_AH: {
 202                 struct ip_auth_hdr _ahdr;
 203                 const struct ip_auth_hdr *ah;
 204
 205                 if (ntohs(ih->frag_off) & IP_OFFSET)
 206                         break;
 207
 208                 /* Max length: 9 "PROTO=AH " */
 209                 nf_log_buf_add(m, "PROTO=AH ");
 210
 211                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 212                 ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
 213                                         sizeof(_ahdr), &_ahdr);
 214                 if (ah == NULL) {
 215                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 216                                        skb->len - iphoff - ih->ihl*4);
 217                         break;
 218                 }
 219
 220                 /* Length: 15 "SPI=0xF1234567 " */
 221                 nf_log_buf_add(m, "SPI=0x%x ", ntohl(ah->spi));
 222                 break;
 223         }
 224         case IPPROTO_ESP: {
 225                 struct ip_esp_hdr _esph;
 226                 const struct ip_esp_hdr *eh;
 227
 228                 /* Max length: 10 "PROTO=ESP " */
 229                 nf_log_buf_add(m, "PROTO=ESP ");
 230
 231                 if (ntohs(ih->frag_off) & IP_OFFSET)
 232                         break;
 233
 234                 /* Max length: 25 "INCOMPLETE [65535 bytes] " */
 235                 eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
 236                                         sizeof(_esph), &_esph);
 237                 if (eh == NULL) {
 238                         nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
 239                                        skb->len - iphoff - ih->ihl*4);
 240                         break;
 241                 }
 242
 243                 /* Length: 15 "SPI=0xF1234567 " */
 244                 nf_log_buf_add(m, "SPI=0x%x ", ntohl(eh->spi));
 245                 break;
 246         }
 247         /* Max length: 10 "PROTO 255 " */
 248         default:
 249                 nf_log_buf_add(m, "PROTO=%u ", ih->protocol);
 250         }
 251
 252         /* Max length: 15 "UID=4294967295 " */
 253         if ((logflags & XT_LOG_UID) && !iphoff)
 254                 nf_log_dump_sk_uid_gid(m, skb->sk);
 255
 256         /* Max length: 16 "MARK=0xFFFFFFFF " */
 257         if (!iphoff && skb->mark)
 258                 nf_log_buf_add(m, "MARK=0x%x ", skb->mark);
 259
 260         /* Proto    Max log string length */
 261         /* IP:      40+46+6+11+127 = 230 */
 262         /* TCP:     10+max(25,20+30+13+9+32+11+127) = 252 */
 263         /* UDP:     10+max(25,20) = 35 */
 264         /* UDPLITE: 14+max(25,20) = 39 */
 265         /* ICMP:    11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
 266         /* ESP:     10+max(25)+15 = 50 */
 267         /* AH:      9+max(25)+15 = 49 */
 268         /* unknown: 10 */
 269
 270         /* (ICMP allows recursion one level deep) */
 271         /* maxlen =  IP + ICMP +  IP + max(TCP,UDP,ICMP,unknown) */
 272         /* maxlen = 230+   91  + 230 + 252 = 803 */
 273 }
 274
 275 static void dump_ipv4_mac_header(struct nf_log_buf *m,
 276                             const struct nf_loginfo *info,
 277                             const struct sk_buff *skb)
 278 {
 279         struct net_device *dev = skb->dev;
 280         unsigned int logflags = 0;
 281
 282         if (info->type == NF_LOG_TYPE_LOG)
 283                 logflags = info->u.log.logflags;
 284
 285         if (!(logflags & XT_LOG_MACDECODE))
 286                 goto fallback;
 287
 288         switch (dev->type) {
 289         case ARPHRD_ETHER:
 290                 nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
 291                                eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
 292                                ntohs(eth_hdr(skb)->h_proto));
 293                 return;
 294         default:
 295                 break;
 296         }
 297
 298 fallback:
 299         nf_log_buf_add(m, "MAC=");
 300         if (dev->hard_header_len &&
 301             skb->mac_header != skb->network_header) {
 302                 const unsigned char *p = skb_mac_header(skb);
 303                 unsigned int i;
 304
 305                 nf_log_buf_add(m, "%02x", *p++);
 306                 for (i = 1; i < dev->hard_header_len; i++, p++)
 307                         nf_log_buf_add(m, ":%02x", *p);
 308         }
 309         nf_log_buf_add(m, " ");
 310 }
 311
 312 static void nf_log_ip_packet(struct net *net, u_int8_t pf,
 313                              unsigned int hooknum, const struct sk_buff *skb,
 314                              const struct net_device *in,
 315                              const struct net_device *out,
 316                              const struct nf_loginfo *loginfo,
 317                              const char *prefix)
 318 {
 319         struct nf_log_buf *m;
 320
 321         /* FIXME: Disabled from containers until syslog ns is supported */
 322         if (!net_eq(net, &init_net))
 323                 return;
 324
 325         m = nf_log_buf_open();
 326
 327         if (!loginfo)
 328                 loginfo = &default_loginfo;
 329
 330         nf_log_dump_packet_common(m, pf, hooknum, skb, in,
 331                                   out, loginfo, prefix);
 332
 333         if (in != NULL)
 334                 dump_ipv4_mac_header(m, loginfo, skb);
 335
 336         dump_ipv4_packet(m, loginfo, skb, 0);
 337
 338         nf_log_buf_close(m);
 339 }
 340
 341 static struct nf_logger nf_ip_logger __read_mostly = {
 342         .name           = "nf_log_ipv4",
 343         .type           = NF_LOG_TYPE_LOG,
 344         .logfn          = nf_log_ip_packet,
 345         .me             = THIS_MODULE,
 346 };
 347
 348 static int __net_init nf_log_ipv4_net_init(struct net *net)
 349 {
 350         nf_log_set(net, NFPROTO_IPV4, &nf_ip_logger);
 351         return 0;
 352 }
 353
 354 static void __net_exit nf_log_ipv4_net_exit(struct net *net)
 355 {
 356         nf_log_unset(net, &nf_ip_logger);
 357 }
 358
 359 static struct pernet_operations nf_log_ipv4_net_ops = {
 360         .init = nf_log_ipv4_net_init,
 361         .exit = nf_log_ipv4_net_exit,
 362 };
 363
 364 static int __init nf_log_ipv4_init(void)
 365 {
 366         int ret;
 367
 368         ret = register_pernet_subsys(&nf_log_ipv4_net_ops);
 369         if (ret < 0)
 370                 return ret;
 371
 372         ret = nf_log_register(NFPROTO_IPV4, &nf_ip_logger);
 373         if (ret < 0) {
 374                 pr_err("failed to register logger\n");
 375                 goto err1;
 376         }
 377
 378         return 0;
 379
 380 err1:
 381         unregister_pernet_subsys(&nf_log_ipv4_net_ops);
 382         return ret;
 383 }
 384
 385 static void __exit nf_log_ipv4_exit(void)
 386 {
 387         unregister_pernet_subsys(&nf_log_ipv4_net_ops);
 388         nf_log_unregister(&nf_ip_logger);
 389 }
 390
 391 module_init(nf_log_ipv4_init);
 392 module_exit(nf_log_ipv4_exit);
 393
 394 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
 395 MODULE_DESCRIPTION("Netfilter IPv4 packet logging");
 396 MODULE_LICENSE("GPL");
 397 MODULE_ALIAS_NF_LOGGER(AF_INET, 0);