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         if (audit_enabled == 0)
 128                 goto errout;
 129
 130         ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
 131         if (ab == NULL)
 132                 goto errout;
 133
 134         audit_log_format(ab, "action=%hhu hook=%u len=%u inif=%s outif=%s",
 135                          info->type, par->hooknum, skb->len,
 136                          par->in ? par->in->name : "?",
 137                          par->out ? par->out->name : "?");
 138
 139         if (skb->mark)
 140                 audit_log_format(ab, " mark=%#x", skb->mark);
 141
 142         if (skb->dev && skb->dev->type == ARPHRD_ETHER) {
 143                 audit_log_format(ab, " smac=%pM dmac=%pM macproto=0x%04x",
 144                                  eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
 145                                  ntohs(eth_hdr(skb)->h_proto));
 146
 147                 if (par->family == NFPROTO_BRIDGE) {
 148                         switch (eth_hdr(skb)->h_proto) {
 149                         case __constant_htons(ETH_P_IP):
 150                                 audit_ip4(ab, skb);
 151                                 break;
 152
 153                         case __constant_htons(ETH_P_IPV6):
 154                                 audit_ip6(ab, skb);
 155                                 break;
 156                         }
 157                 }
 158         }
 159
 160         switch (par->family) {
 161         case NFPROTO_IPV4:
 162                 audit_ip4(ab, skb);
 163                 break;
 164
 165         case NFPROTO_IPV6:
 166                 audit_ip6(ab, skb);
 167                 break;
 168         }
 169
 170 #ifdef CONFIG_NETWORK_SECMARK
 171         if (skb->secmark)
 172                 audit_log_secctx(ab, skb->secmark);
 173 #endif
 174
 175         audit_log_end(ab);
 176
 177 errout:
 178         return XT_CONTINUE;
 179 }
 180
 181 static unsigned int
 182 audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
 183 {
 184         audit_tg(skb, par);
 185         return EBT_CONTINUE;
 186 }
 187
 188 static int audit_tg_check(const struct xt_tgchk_param *par)
 189 {
 190         const struct xt_audit_info *info = par->targinfo;
 191
 192         if (info->type > XT_AUDIT_TYPE_MAX) {
 193                 pr_info("Audit type out of range (valid range: 0..%hhu)\n",
 194                         XT_AUDIT_TYPE_MAX);
 195                 return -ERANGE;
 196         }
 197
 198         return 0;
 199 }
 200
 201 static struct xt_target audit_tg_reg[] __read_mostly = {
 202         {
 203                 .name           = "AUDIT",
 204                 .family         = NFPROTO_UNSPEC,
 205                 .target         = audit_tg,
 206                 .targetsize     = sizeof(struct xt_audit_info),
 207                 .checkentry     = audit_tg_check,
 208                 .me             = THIS_MODULE,
 209         },
 210         {
 211                 .name           = "AUDIT",
 212                 .family         = NFPROTO_BRIDGE,
 213                 .target         = audit_tg_ebt,
 214                 .targetsize     = sizeof(struct xt_audit_info),
 215                 .checkentry     = audit_tg_check,
 216                 .me             = THIS_MODULE,
 217         },
 218 };
 219
 220 static int __init audit_tg_init(void)
 221 {
 222         return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 223 }
 224
 225 static void __exit audit_tg_exit(void)
 226 {
 227         xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 228 }
 229
 230 module_init(audit_tg_init);
 231 module_exit(audit_tg_exit);