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..%u)\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);
159