1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * This is a module which is used for logging packets.
4  */
5 
6 /* (C) 1999-2001 Paul `Rusty' Russell
7  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
8  */
9 
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/module.h>
12 #include <linux/spinlock.h>
13 #include <linux/skbuff.h>
14 #include <linux/if_arp.h>
15 #include <linux/ip.h>
16 #include <net/ipv6.h>
17 #include <net/icmp.h>
18 #include <net/udp.h>
19 #include <net/tcp.h>
20 #include <net/route.h>
21 
22 #include <linux/netfilter.h>
23 #include <linux/netfilter/x_tables.h>
24 #include <linux/netfilter/xt_LOG.h>
25 #include <linux/netfilter_ipv6/ip6_tables.h>
26 #include <net/netfilter/nf_log.h>
27 
28 static unsigned int
log_tg(struct sk_buff * skb,const struct xt_action_param * par)29 log_tg(struct sk_buff *skb, const struct xt_action_param *par)
30 {
31 	const struct xt_log_info *loginfo = par->targinfo;
32 	struct net *net = xt_net(par);
33 	struct nf_loginfo li;
34 
35 	li.type = NF_LOG_TYPE_LOG;
36 	li.u.log.level = loginfo->level;
37 	li.u.log.logflags = loginfo->logflags;
38 
39 	nf_log_packet(net, xt_family(par), xt_hooknum(par), skb, xt_in(par),
40 		      xt_out(par), &li, "%s", loginfo->prefix);
41 	return XT_CONTINUE;
42 }
43 
log_tg_check(const struct xt_tgchk_param * par)44 static int log_tg_check(const struct xt_tgchk_param *par)
45 {
46 	const struct xt_log_info *loginfo = par->targinfo;
47 	int ret;
48 
49 	if (par->family != NFPROTO_IPV4 && par->family != NFPROTO_IPV6)
50 		return -EINVAL;
51 
52 	if (loginfo->level >= 8) {
53 		pr_debug("level %u >= 8\n", loginfo->level);
54 		return -EINVAL;
55 	}
56 
57 	if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
58 		pr_debug("prefix is not null-terminated\n");
59 		return -EINVAL;
60 	}
61 
62 	ret = nf_logger_find_get(par->family, NF_LOG_TYPE_LOG);
63 	if (ret != 0 && !par->nft_compat) {
64 		request_module("%s", "nf_log_syslog");
65 
66 		ret = nf_logger_find_get(par->family, NF_LOG_TYPE_LOG);
67 	}
68 
69 	return ret;
70 }
71 
log_tg_destroy(const struct xt_tgdtor_param * par)72 static void log_tg_destroy(const struct xt_tgdtor_param *par)
73 {
74 	nf_logger_put(par->family, NF_LOG_TYPE_LOG);
75 }
76 
77 static struct xt_target log_tg_regs[] __read_mostly = {
78 	{
79 		.name		= "LOG",
80 		.family		= NFPROTO_IPV4,
81 		.target		= log_tg,
82 		.targetsize	= sizeof(struct xt_log_info),
83 		.checkentry	= log_tg_check,
84 		.destroy	= log_tg_destroy,
85 		.me		= THIS_MODULE,
86 	},
87 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
88 	{
89 		.name		= "LOG",
90 		.family		= NFPROTO_IPV6,
91 		.target		= log_tg,
92 		.targetsize	= sizeof(struct xt_log_info),
93 		.checkentry	= log_tg_check,
94 		.destroy	= log_tg_destroy,
95 		.me		= THIS_MODULE,
96 	},
97 #endif
98 };
99 
log_tg_init(void)100 static int __init log_tg_init(void)
101 {
102 	return xt_register_targets(log_tg_regs, ARRAY_SIZE(log_tg_regs));
103 }
104 
log_tg_exit(void)105 static void __exit log_tg_exit(void)
106 {
107 	xt_unregister_targets(log_tg_regs, ARRAY_SIZE(log_tg_regs));
108 }
109 
110 module_init(log_tg_init);
111 module_exit(log_tg_exit);
112 
113 MODULE_LICENSE("GPL");
114 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
115 MODULE_AUTHOR("Jan Rekorajski <baggins@pld.org.pl>");
116 MODULE_DESCRIPTION("Xtables: IPv4/IPv6 packet logging");
117 MODULE_ALIAS("ipt_LOG");
118 MODULE_ALIAS("ip6t_LOG");
119 MODULE_SOFTDEP("pre: nf_log_syslog");
120