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
23 MODULE_LICENSE("GPL");
24 MODULE_AUTHOR("Thomas Graf <tgraf@redhat.com>");
25 MODULE_DESCRIPTION("Xtables: creates audit records for dropped/accepted packets");
26 MODULE_ALIAS("ipt_AUDIT");
27 MODULE_ALIAS("ip6t_AUDIT");
28 MODULE_ALIAS("ebt_AUDIT");
29 MODULE_ALIAS("arpt_AUDIT");
30
audit_ip4(struct audit_buffer * ab,struct sk_buff * skb)31 static 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
audit_ip6(struct audit_buffer * ab,struct sk_buff * skb)46 static 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
66 static unsigned int
audit_tg(struct sk_buff * skb,const struct xt_action_param * par)67 audit_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
104 errout:
105 return XT_CONTINUE;
106 }
107
108 static unsigned int
audit_tg_ebt(struct sk_buff * skb,const struct xt_action_param * par)109 audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
110 {
111 audit_tg(skb, par);
112 return EBT_CONTINUE;
113 }
114
audit_tg_check(const struct xt_tgchk_param * par)115 static 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
128 static 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
audit_tg_init(void)147 static int __init audit_tg_init(void)
148 {
149 return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
150 }
151
audit_tg_exit(void)152 static void __exit audit_tg_exit(void)
153 {
154 xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
155 }
156
157 module_init(audit_tg_init);
158 module_exit(audit_tg_exit);
159