net/netfilter/xt_AUDIT.c

   1 /*
   2  * Creates audit record for dropped/accepted packets
   3  *
   4  * (C) 2010-2011 Thomas Graf <tgraf@redhat.com>
   5  * (C) 2010-2011 Red Hat, Inc.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10 */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/audit.h>
  15 #include <linux/module.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/tcp.h>
  18 #include <linux/udp.h>
  19 #include <linux/if_arp.h>
  20 #include <linux/netfilter/x_tables.h>
  21 #include <linux/netfilter/xt_AUDIT.h>
  22 #include <linux/netfilter_bridge/ebtables.h>
  23 #include <net/ipv6.h>
  24 #include <net/ip.h>
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("Thomas Graf <tgraf@redhat.com>");
  28 MODULE_DESCRIPTION("Xtables: creates audit records for dropped/accepted packets");
  29 MODULE_ALIAS("ipt_AUDIT");
  30 MODULE_ALIAS("ip6t_AUDIT");
  31 MODULE_ALIAS("ebt_AUDIT");
  32 MODULE_ALIAS("arpt_AUDIT");
  33
  34 static void audit_proto(struct audit_buffer *ab, struct sk_buff *skb,
  35                         unsigned int proto, unsigned int offset)
  36 {
  37         switch (proto) {
  38         case IPPROTO_TCP:
  39         case IPPROTO_UDP:
  40         case IPPROTO_UDPLITE: {
  41                 const __be16 *pptr;
  42                 __be16 _ports[2];
  43
  44                 pptr = skb_header_pointer(skb, offset, sizeof(_ports), _ports);
  45                 if (pptr == NULL) {
  46                         audit_log_format(ab, " truncated=1");
  47                         return;
  48                 }
  49
  50                 audit_log_format(ab, " sport=%hu dport=%hu",
  51                                  ntohs(pptr[0]), ntohs(pptr[1]));
  52                 }
  53                 break;
  54
  55         case IPPROTO_ICMP:
  56         case IPPROTO_ICMPV6: {
  57                 const u8 *iptr;
  58                 u8 _ih[2];
  59
  60                 iptr = skb_header_pointer(skb, offset, sizeof(_ih), &_ih);
  61                 if (iptr == NULL) {
  62                         audit_log_format(ab, " truncated=1");
  63                         return;
  64                 }
  65
  66                 audit_log_format(ab, " icmptype=%hhu icmpcode=%hhu",
  67                                  iptr[0], iptr[1]);
  68
  69                 }
  70                 break;
  71         }
  72 }
  73
  74 static void audit_ip4(struct audit_buffer *ab, struct sk_buff *skb)
  75 {
  76         struct iphdr _iph;
  77         const struct iphdr *ih;
  78
  79         ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
  80         if (!ih) {
  81                 audit_log_format(ab, " truncated=1");
  82                 return;
  83         }
  84
  85         audit_log_format(ab, " saddr=%pI4 daddr=%pI4 ipid=%hu proto=%hhu",
  86                 &ih->saddr, &ih->daddr, ntohs(ih->id), ih->protocol);
  87
  88         if (ntohs(ih->frag_off) & IP_OFFSET) {
  89                 audit_log_format(ab, " frag=1");
  90                 return;
  91         }
  92
  93         audit_proto(ab, skb, ih->protocol, ih->ihl * 4);
  94 }
  95
  96 static void audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
  97 {
  98         struct ipv6hdr _ip6h;
  99         const struct ipv6hdr *ih;
 100         u8 nexthdr;
 101         __be16 frag_off;
 102         int offset;
 103
 104         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h);
 105         if (!ih) {
 106                 audit_log_format(ab, " truncated=1");
 107                 return;
 108         }
 109
 110         nexthdr = ih->nexthdr;
 111         offset = ipv6_skip_exthdr(skb, skb_network_offset(skb) + sizeof(_ip6h),
 112                                   &nexthdr, &frag_off);
 113
 114         audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu",
 115                          &ih->saddr, &ih->daddr, nexthdr);
 116
 117         if (offset)
 118                 audit_proto(ab, skb, nexthdr, offset);
 119 }
 120
 121 static unsigned int
 122 audit_tg(struct sk_buff *skb, const struct xt_action_param *par)
 123 {
 124         const struct xt_audit_info *info = par->targinfo;
 125         struct audit_buffer *ab;
 126
 127         ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
 128         if (ab == NULL)
 129                 goto errout;
 130
 131         audit_log_format(ab, "action=%hhu hook=%u len=%u inif=%s outif=%s",
 132                          info->type, par->hooknum, skb->len,
 133                          par->in ? par->in->name : "?",
 134                          par->out ? par->out->name : "?");
 135
 136         if (skb->mark)
 137                 audit_log_format(ab, " mark=%#x", skb->mark);
 138
 139         if (skb->dev && skb->dev->type == ARPHRD_ETHER) {
 140                 audit_log_format(ab, " smac=%pM dmac=%pM macproto=0x%04x",
 141                                  eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
 142                                  ntohs(eth_hdr(skb)->h_proto));
 143
 144                 if (par->family == NFPROTO_BRIDGE) {
 145                         switch (eth_hdr(skb)->h_proto) {
 146                         case __constant_htons(ETH_P_IP):
 147                                 audit_ip4(ab, skb);
 148                                 break;
 149
 150                         case __constant_htons(ETH_P_IPV6):
 151                                 audit_ip6(ab, skb);
 152                                 break;
 153                         }
 154                 }
 155         }
 156
 157         switch (par->family) {
 158         case NFPROTO_IPV4:
 159                 audit_ip4(ab, skb);
 160                 break;
 161
 162         case NFPROTO_IPV6:
 163                 audit_ip6(ab, skb);
 164                 break;
 165         }
 166
 167 #ifdef CONFIG_NETWORK_SECMARK
 168         if (skb->secmark)
 169                 audit_log_secctx(ab, skb->secmark);
 170 #endif
 171
 172         audit_log_end(ab);
 173
 174 errout:
 175         return XT_CONTINUE;
 176 }
 177
 178 static unsigned int
 179 audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
 180 {
 181         audit_tg(skb, par);
 182         return EBT_CONTINUE;
 183 }
 184
 185 static int audit_tg_check(const struct xt_tgchk_param *par)
 186 {
 187         const struct xt_audit_info *info = par->targinfo;
 188
 189         if (info->type > XT_AUDIT_TYPE_MAX) {
 190                 pr_info("Audit type out of range (valid range: 0..%hhu)\n",
 191                         XT_AUDIT_TYPE_MAX);
 192                 return -ERANGE;
 193         }
 194
 195         return 0;
 196 }
 197
 198 static struct xt_target audit_tg_reg[] __read_mostly = {
 199         {
 200                 .name           = "AUDIT",
 201                 .family         = NFPROTO_UNSPEC,
 202                 .target         = audit_tg,
 203                 .targetsize     = sizeof(struct xt_audit_info),
 204                 .checkentry     = audit_tg_check,
 205                 .me             = THIS_MODULE,
 206         },
 207         {
 208                 .name           = "AUDIT",
 209                 .family         = NFPROTO_BRIDGE,
 210                 .target         = audit_tg_ebt,
 211                 .targetsize     = sizeof(struct xt_audit_info),
 212                 .checkentry     = audit_tg_check,
 213                 .me             = THIS_MODULE,
 214         },
 215 };
 216
 217 static int __init audit_tg_init(void)
 218 {
 219         return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 220 }
 221
 222 static void __exit audit_tg_exit(void)
 223 {
 224         xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 225 }
 226
 227 module_init(audit_tg_init);
 228 module_exit(audit_tg_exit);