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         int offset;
 102
 103         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h);
 104         if (!ih) {
 105                 audit_log_format(ab, " truncated=1");
 106                 return;
 107         }
 108
 109         nexthdr = ih->nexthdr;
 110         offset = ipv6_skip_exthdr(skb, skb_network_offset(skb) + sizeof(_ip6h),
 111                                   &nexthdr);
 112
 113         audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu",
 114                          &ih->saddr, &ih->daddr, nexthdr);
 115
 116         if (offset)
 117                 audit_proto(ab, skb, nexthdr, offset);
 118 }
 119
 120 static unsigned int
 121 audit_tg(struct sk_buff *skb, const struct xt_action_param *par)
 122 {
 123         const struct xt_audit_info *info = par->targinfo;
 124         struct audit_buffer *ab;
 125
 126         ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
 127         if (ab == NULL)
 128                 goto errout;
 129
 130         audit_log_format(ab, "action=%hhu hook=%u len=%u inif=%s outif=%s",
 131                          info->type, par->hooknum, skb->len,
 132                          par->in ? par->in->name : "?",
 133                          par->out ? par->out->name : "?");
 134
 135         if (skb->mark)
 136                 audit_log_format(ab, " mark=%#x", skb->mark);
 137
 138         if (skb->dev && skb->dev->type == ARPHRD_ETHER) {
 139                 audit_log_format(ab, " smac=%pM dmac=%pM macproto=0x%04x",
 140                                  eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
 141                                  ntohs(eth_hdr(skb)->h_proto));
 142
 143                 if (par->family == NFPROTO_BRIDGE) {
 144                         switch (eth_hdr(skb)->h_proto) {
 145                         case __constant_htons(ETH_P_IP):
 146                                 audit_ip4(ab, skb);
 147                                 break;
 148
 149                         case __constant_htons(ETH_P_IPV6):
 150                                 audit_ip6(ab, skb);
 151                                 break;
 152                         }
 153                 }
 154         }
 155
 156         switch (par->family) {
 157         case NFPROTO_IPV4:
 158                 audit_ip4(ab, skb);
 159                 break;
 160
 161         case NFPROTO_IPV6:
 162                 audit_ip6(ab, skb);
 163                 break;
 164         }
 165
 166         audit_log_end(ab);
 167
 168 errout:
 169         return XT_CONTINUE;
 170 }
 171
 172 static unsigned int
 173 audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
 174 {
 175         audit_tg(skb, par);
 176         return EBT_CONTINUE;
 177 }
 178
 179 static int audit_tg_check(const struct xt_tgchk_param *par)
 180 {
 181         const struct xt_audit_info *info = par->targinfo;
 182
 183         if (info->type > XT_AUDIT_TYPE_MAX) {
 184                 pr_info("Audit type out of range (valid range: 0..%hhu)\n",
 185                         XT_AUDIT_TYPE_MAX);
 186                 return -ERANGE;
 187         }
 188
 189         return 0;
 190 }
 191
 192 static struct xt_target audit_tg_reg[] __read_mostly = {
 193         {
 194                 .name           = "AUDIT",
 195                 .family         = NFPROTO_UNSPEC,
 196                 .target         = audit_tg,
 197                 .targetsize     = sizeof(struct xt_audit_info),
 198                 .checkentry     = audit_tg_check,
 199                 .me             = THIS_MODULE,
 200         },
 201         {
 202                 .name           = "AUDIT",
 203                 .family         = NFPROTO_BRIDGE,
 204                 .target         = audit_tg_ebt,
 205                 .targetsize     = sizeof(struct xt_audit_info),
 206                 .checkentry     = audit_tg_check,
 207                 .me             = THIS_MODULE,
 208         },
 209 };
 210
 211 static int __init audit_tg_init(void)
 212 {
 213         return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 214 }
 215
 216 static void __exit audit_tg_exit(void)
 217 {
 218         xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 219 }
 220
 221 module_init(audit_tg_init);
 222 module_exit(audit_tg_exit);