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	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 htons(ETH_P_IP):
150				audit_ip4(ab, skb);
151				break;
152
153			case 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
177errout:
178	return XT_CONTINUE;
179}
180
181static unsigned int
182audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
183{
184	audit_tg(skb, par);
185	return EBT_CONTINUE;
186}
187
188static 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
201static 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
220static int __init audit_tg_init(void)
221{
222	return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
223}
224
225static void __exit audit_tg_exit(void)
226{
227	xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
228}
229
230module_init(audit_tg_init);
231module_exit(audit_tg_exit);
232