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
26 MODULE_LICENSE("GPL");
27 MODULE_AUTHOR("Thomas Graf <tgraf@redhat.com>");
28 MODULE_DESCRIPTION("Xtables: creates audit records for dropped/accepted packets");
29 MODULE_ALIAS("ipt_AUDIT");
30 MODULE_ALIAS("ip6t_AUDIT");
31 MODULE_ALIAS("ebt_AUDIT");
32 MODULE_ALIAS("arpt_AUDIT");
33
audit_proto(struct audit_buffer * ab,struct sk_buff * skb,unsigned int proto,unsigned int offset)34 static 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
audit_ip4(struct audit_buffer * ab,struct sk_buff * skb)74 static 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
audit_ip6(struct audit_buffer * ab,struct sk_buff * skb)96 static 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
121 static unsigned int
audit_tg(struct sk_buff * skb,const struct xt_action_param * par)122 audit_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 ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
128 if (ab == NULL)
129 goto errout;
130
131 audit_log_format(ab, "action=%hhu hook=%u len=%u inif=%s outif=%s",
132 info->type, par->hooknum, skb->len,
133 par->in ? par->in->name : "?",
134 par->out ? par->out->name : "?");
135
136 if (skb->mark)
137 audit_log_format(ab, " mark=%#x", skb->mark);
138
139 if (skb->dev && skb->dev->type == ARPHRD_ETHER) {
140 audit_log_format(ab, " smac=%pM dmac=%pM macproto=0x%04x",
141 eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
142 ntohs(eth_hdr(skb)->h_proto));
143
144 if (par->family == NFPROTO_BRIDGE) {
145 switch (eth_hdr(skb)->h_proto) {
146 case __constant_htons(ETH_P_IP):
147 audit_ip4(ab, skb);
148 break;
149
150 case __constant_htons(ETH_P_IPV6):
151 audit_ip6(ab, skb);
152 break;
153 }
154 }
155 }
156
157 switch (par->family) {
158 case NFPROTO_IPV4:
159 audit_ip4(ab, skb);
160 break;
161
162 case NFPROTO_IPV6:
163 audit_ip6(ab, skb);
164 break;
165 }
166
167 #ifdef CONFIG_NETWORK_SECMARK
168 if (skb->secmark)
169 audit_log_secctx(ab, skb->secmark);
170 #endif
171
172 audit_log_end(ab);
173
174 errout:
175 return XT_CONTINUE;
176 }
177
178 static unsigned int
audit_tg_ebt(struct sk_buff * skb,const struct xt_action_param * par)179 audit_tg_ebt(struct sk_buff *skb, const struct xt_action_param *par)
180 {
181 audit_tg(skb, par);
182 return EBT_CONTINUE;
183 }
184
audit_tg_check(const struct xt_tgchk_param * par)185 static int audit_tg_check(const struct xt_tgchk_param *par)
186 {
187 const struct xt_audit_info *info = par->targinfo;
188
189 if (info->type > XT_AUDIT_TYPE_MAX) {
190 pr_info("Audit type out of range (valid range: 0..%hhu)\n",
191 XT_AUDIT_TYPE_MAX);
192 return -ERANGE;
193 }
194
195 return 0;
196 }
197
198 static struct xt_target audit_tg_reg[] __read_mostly = {
199 {
200 .name = "AUDIT",
201 .family = NFPROTO_UNSPEC,
202 .target = audit_tg,
203 .targetsize = sizeof(struct xt_audit_info),
204 .checkentry = audit_tg_check,
205 .me = THIS_MODULE,
206 },
207 {
208 .name = "AUDIT",
209 .family = NFPROTO_BRIDGE,
210 .target = audit_tg_ebt,
211 .targetsize = sizeof(struct xt_audit_info),
212 .checkentry = audit_tg_check,
213 .me = THIS_MODULE,
214 },
215 };
216
audit_tg_init(void)217 static int __init audit_tg_init(void)
218 {
219 return xt_register_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
220 }
221
audit_tg_exit(void)222 static void __exit audit_tg_exit(void)
223 {
224 xt_unregister_targets(audit_tg_reg, ARRAY_SIZE(audit_tg_reg));
225 }
226
227 module_init(audit_tg_init);
228 module_exit(audit_tg_exit);
229