linux/net/netfilter/xt_AUDIT.c
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   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
  26MODULE_LICENSE("GPL");
  27MODULE_AUTHOR("Thomas Graf <tgraf@redhat.com>");
  28MODULE_DESCRIPTION("Xtables: creates audit records for dropped/accepted packets");
  29MODULE_ALIAS("ipt_AUDIT");
  30MODULE_ALIAS("ip6t_AUDIT");
  31MODULE_ALIAS("ebt_AUDIT");
  32MODULE_ALIAS("arpt_AUDIT");
  33
  34static 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
  74static 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
  96static 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
 121static unsigned int
 122audit_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
 174errout:
 175        return XT_CONTINUE;
 176}
 177
 178static unsigned int
 179audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
 180{
 181        audit_tg(skb, par);
 182        return EBT_CONTINUE;
 183}
 184
 185static 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
 198static 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
 217static int __init audit_tg_init(void)
 218{
 219        return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 220}
 221
 222static void __exit audit_tg_exit(void)
 223{
 224        xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
 225}
 226
 227module_init(audit_tg_init);
 228module_exit(audit_tg_exit);
 229
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