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 bool audit_ip4(struct audit_buffer *ab, struct sk_buff *skb)
  35 {
  36         struct iphdr _iph;
  37         const struct iphdr *ih;
  38
  39         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_iph), &_iph);
  40         if (!ih)
  41                 return false;
  42
  43         audit_log_format(ab, " saddr=%pI4 daddr=%pI4 proto=%hhu",
  44                          &ih->saddr, &ih->daddr, ih->protocol);
  45
  46         return true;
  47 }
  48
  49 static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
  50 {
  51         struct ipv6hdr _ip6h;
  52         const struct ipv6hdr *ih;
  53         u8 nexthdr;
  54         __be16 frag_off;
  55
  56         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h);
  57         if (!ih)
  58                 return false;
  59
  60         nexthdr = ih->nexthdr;
  61         ipv6_skip_exthdr(skb, skb_network_offset(skb) + sizeof(_ip6h), &nexthdr, &frag_off);
  62
  63         audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu",
  64                          &ih->saddr, &ih->daddr, nexthdr);
  65
  66         return true;
  67 }
  68
  69 static unsigned int
  70 audit_tg(struct sk_buff *skb, const struct xt_action_param *par)
  71 {
  72         struct audit_buffer *ab;
  73         int fam = -1;
  74
  75         if (audit_enabled == 0)
  76                 goto errout;
  77         ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
  78         if (ab == NULL)
  79                 goto errout;
  80
  81         audit_log_format(ab, "mark=%#x", skb->mark);
  82
  83         switch (xt_family(par)) {
  84         case NFPROTO_BRIDGE:
  85                 switch (eth_hdr(skb)->h_proto) {
  86                 case htons(ETH_P_IP):
  87                         fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
  88                         break;
  89                 case htons(ETH_P_IPV6):
  90                         fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
  91                         break;
  92                 }
  93                 break;
  94         case NFPROTO_IPV4:
  95                 fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
  96                 break;
  97         case NFPROTO_IPV6:
  98                 fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
  99                 break;
 100         }
 101
 102         if (fam == -1)
 103                 audit_log_format(ab, " saddr=? daddr=? proto=-1");
 104
 105         audit_log_end(ab);
 106
 107 errout:
 108         return XT_CONTINUE;
 109 }
 110
 111 static unsigned int
 112 audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
 113 {
 114         audit_tg(skb, par);
 115         return EBT_CONTINUE;
 116 }
 117
 118 static int audit_tg_check(const struct xt_tgchk_param *par)
 119 {
 120         const struct xt_audit_info *info = par->targinfo;
 121
 122         if (info->type > XT_AUDIT_TYPE_MAX) {
 123                 pr_info_ratelimited("Audit type out of range (valid range: 0..%hhu)\n",
 124                                     XT_AUDIT_TYPE_MAX);
 125                 return -ERANGE;
 126         }
 127
 128         return 0;
 129 }
 130
 131 static struct xt_target audit_tg_reg[] __read_mostly = {
 132         {
 133                 .name           = "AUDIT",
 134                 .family         = NFPROTO_UNSPEC,
 135                 .target         = audit_tg,
 136                 .targetsize     = sizeof(struct xt_audit_info),
 137                 .checkentry     = audit_tg_check,
 138                 .me             = THIS_MODULE,
 139         },
 140         {
 141                 .name           = "AUDIT",
 142                 .family         = NFPROTO_BRIDGE,
 143                 .target         = audit_tg_ebt,
 144                 .targetsize     = sizeof(struct xt_audit_info),
 145                 .checkentry     = audit_tg_check,
 146                 .me             = THIS_MODULE,
 147         },
 148 };
 149
 150 static int __init audit_tg_init(void)
 151 {
 152         return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 153 }
 154
 155 static void __exit audit_tg_exit(void)
 156 {
 157         xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 158 }
 159
 160 module_init(audit_tg_init);
 161 module_exit(audit_tg_exit);