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, offset: skb_network_offset(skb), len: sizeof(_iph), buffer: &_iph);
37 if (!ih)
38 return false;
39
40 audit_log_format(ab, fmt: " 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, offset: skb_network_offset(skb), len: sizeof(_ip6h), buffer: &_ip6h);
54 if (!ih)
55 return false;
56
57 nexthdr = ih->nexthdr;
58 ipv6_skip_exthdr(skb, start: skb_network_offset(skb) + sizeof(_ip6h), nexthdrp: &nexthdr, frag_offp: &frag_off);
59
60 audit_log_format(ab, fmt: " 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, fmt: "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, fmt: " 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(target: audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
150}
151
152static void __exit audit_tg_exit(void)
153{
154 xt_unregister_targets(target: audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
155}
156
157module_init(audit_tg_init);
158module_exit(audit_tg_exit);
159

source code of linux/net/netfilter/xt_AUDIT.c