net/netfilter/xt_AUDIT.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Creates audit record for dropped/accepted packets
   4  *
   5  * (C) 2010-2011 Thomas Graf <tgraf@redhat.com>
   6  * (C) 2010-2011 Red Hat, Inc.
   7 */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/audit.h>
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/tcp.h>
  15 #include <linux/udp.h>
  16 #include <linux/if_arp.h>
  17 #include <linux/netfilter/x_tables.h>
  18 #include <linux/netfilter/xt_AUDIT.h>
  19 #include <linux/netfilter_bridge/ebtables.h>
  20 #include <net/ipv6.h>
  21 #include <net/ip.h>
  22
  23 MODULE_LICENSE("GPL");
  24 MODULE_AUTHOR("Thomas Graf <tgraf@redhat.com>");
  25 MODULE_DESCRIPTION("Xtables: creates audit records for dropped/accepted packets");
  26 MODULE_ALIAS("ipt_AUDIT");
  27 MODULE_ALIAS("ip6t_AUDIT");
  28 MODULE_ALIAS("ebt_AUDIT");
  29 MODULE_ALIAS("arpt_AUDIT");
  30
  31 static bool audit_ip4(struct audit_buffer *ab, struct sk_buff *skb)
  32 {
  33         struct iphdr _iph;
  34         const struct iphdr *ih;
  35
  36         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_iph), &_iph);
  37         if (!ih)
  38                 return false;
  39
  40         audit_log_format(ab, " saddr=%pI4 daddr=%pI4 proto=%hhu",
  41                          &ih->saddr, &ih->daddr, ih->protocol);
  42
  43         return true;
  44 }
  45
  46 static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
  47 {
  48         struct ipv6hdr _ip6h;
  49         const struct ipv6hdr *ih;
  50         u8 nexthdr;
  51         __be16 frag_off;
  52
  53         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h);
  54         if (!ih)
  55                 return false;
  56
  57         nexthdr = ih->nexthdr;
  58         ipv6_skip_exthdr(skb, skb_network_offset(skb) + sizeof(_ip6h), &nexthdr, &frag_off);
  59
  60         audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu",
  61                          &ih->saddr, &ih->daddr, nexthdr);
  62
  63         return true;
  64 }
  65
  66 static unsigned int
  67 audit_tg(struct sk_buff *skb, const struct xt_action_param *par)
  68 {
  69         struct audit_buffer *ab;
  70         int fam = -1;
  71
  72         if (audit_enabled == AUDIT_OFF)
  73                 goto errout;
  74         ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
  75         if (ab == NULL)
  76                 goto errout;
  77
  78         audit_log_format(ab, "mark=%#x", skb->mark);
  79
  80         switch (xt_family(par)) {
  81         case NFPROTO_BRIDGE:
  82                 switch (eth_hdr(skb)->h_proto) {
  83                 case htons(ETH_P_IP):
  84                         fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
  85                         break;
  86                 case htons(ETH_P_IPV6):
  87                         fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
  88                         break;
  89                 }
  90                 break;
  91         case NFPROTO_IPV4:
  92                 fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
  93                 break;
  94         case NFPROTO_IPV6:
  95                 fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
  96                 break;
  97         }
  98
  99         if (fam == -1)
 100                 audit_log_format(ab, " saddr=? daddr=? proto=-1");
 101
 102         audit_log_end(ab);
 103
 104 errout:
 105         return XT_CONTINUE;
 106 }
 107
 108 static unsigned int
 109 audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
 110 {
 111         audit_tg(skb, par);
 112         return EBT_CONTINUE;
 113 }
 114
 115 static int audit_tg_check(const struct xt_tgchk_param *par)
 116 {
 117         const struct xt_audit_info *info = par->targinfo;
 118
 119         if (info->type > XT_AUDIT_TYPE_MAX) {
 120                 pr_info_ratelimited("Audit type out of range (valid range: 0..%hhu)\n",
 121                                     XT_AUDIT_TYPE_MAX);
 122                 return -ERANGE;
 123         }
 124
 125         return 0;
 126 }
 127
 128 static struct xt_target audit_tg_reg[] __read_mostly = {
 129         {
 130                 .name           = "AUDIT",
 131                 .family         = NFPROTO_UNSPEC,
 132                 .target         = audit_tg,
 133                 .targetsize     = sizeof(struct xt_audit_info),
 134                 .checkentry     = audit_tg_check,
 135                 .me             = THIS_MODULE,
 136         },
 137         {
 138                 .name           = "AUDIT",
 139                 .family         = NFPROTO_BRIDGE,
 140                 .target         = audit_tg_ebt,
 141                 .targetsize     = sizeof(struct xt_audit_info),
 142                 .checkentry     = audit_tg_check,
 143                 .me             = THIS_MODULE,
 144         },
 145 };
 146
 147 static int __init audit_tg_init(void)
 148 {
 149         return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 150 }
 151
 152 static void __exit audit_tg_exit(void)
 153 {
 154         xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 155 }
 156
 157 module_init(audit_tg_init);
 158 module_exit(audit_tg_exit);