/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
 23MODULE_LICENSE("GPL");
 24MODULE_AUTHOR("Thomas Graf <tgraf@redhat.com>");
 25MODULE_DESCRIPTION("Xtables: creates audit records for dropped/accepted packets");
 26MODULE_ALIAS("ipt_AUDIT");
 27MODULE_ALIAS("ip6t_AUDIT");
 28MODULE_ALIAS("ebt_AUDIT");
 29MODULE_ALIAS("arpt_AUDIT");
 30
 31static 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
 46static 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
 66static unsigned int
 67audit_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
104errout:
105	return XT_CONTINUE;
106}
107
108static unsigned int
109audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
110{
111	audit_tg(skb, par);
112	return EBT_CONTINUE;
113}
114
115static 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
128static 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
147static int __init audit_tg_init(void)
148{
149	return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
150}
151
152static void __exit audit_tg_exit(void)
153{
154	xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
155}
156
157module_init(audit_tg_init);
158module_exit(audit_tg_exit);