1 /* Netfilter messages via netlink socket. Allows for user space
2 * protocol helpers and general trouble making from userspace.
3 *
4 * (C) 2001 by Jay Schulist <jschlst@samba.org>,
5 * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
6 * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
7 *
8 * Initial netfilter messages via netlink development funded and
9 * generally made possible by Network Robots, Inc. (www.networkrobots.com)
10 *
11 * Further development of this code funded by Astaro AG (http://www.astaro.com)
12 *
13 * This software may be used and distributed according to the terms
14 * of the GNU General Public License, incorporated herein by reference.
15 */
16
17 #include <linux/module.h>
18 #include <linux/types.h>
19 #include <linux/socket.h>
20 #include <linux/kernel.h>
21 #include <linux/major.h>
22 #include <linux/timer.h>
23 #include <linux/string.h>
24 #include <linux/sockios.h>
25 #include <linux/net.h>
26 #include <linux/fcntl.h>
27 #include <linux/skbuff.h>
28 #include <asm/uaccess.h>
29 #include <asm/system.h>
30 #include <net/sock.h>
31 #include <net/netlink.h>
32 #include <linux/init.h>
33
34 #include <linux/netlink.h>
35 #include <linux/netfilter/nfnetlink.h>
36
37 MODULE_LICENSE("GPL");
38 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
39 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
40
41 static char __initdata nfversion[] = "0.30";
42
43 static struct sock *nfnl = NULL;
44 static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
45 static DEFINE_MUTEX(nfnl_mutex);
46
47 static inline void nfnl_lock(void)
48 {
49 mutex_lock(&nfnl_mutex);
50 }
51
52 static inline void nfnl_unlock(void)
53 {
54 mutex_unlock(&nfnl_mutex);
55 }
56
57 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
58 {
59 nfnl_lock();
60 if (subsys_table[n->subsys_id]) {
61 nfnl_unlock();
62 return -EBUSY;
63 }
64 subsys_table[n->subsys_id] = n;
65 nfnl_unlock();
66
67 return 0;
68 }
69 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
70
71 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
72 {
73 nfnl_lock();
74 subsys_table[n->subsys_id] = NULL;
75 nfnl_unlock();
76
77 return 0;
78 }
79 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
80
81 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
82 {
83 u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
84
85 if (subsys_id >= NFNL_SUBSYS_COUNT)
86 return NULL;
87
88 return subsys_table[subsys_id];
89 }
90
91 static inline const struct nfnl_callback *
92 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss)
93 {
94 u_int8_t cb_id = NFNL_MSG_TYPE(type);
95
96 if (cb_id >= ss->cb_count)
97 return NULL;
98
99 return &ss->cb[cb_id];
100 }
101
102 int nfnetlink_has_listeners(unsigned int group)
103 {
104 return netlink_has_listeners(nfnl, group);
105 }
106 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
107
108 int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
109 {
110 return nlmsg_notify(nfnl, skb, pid, group, echo, gfp_any());
111 }
112 EXPORT_SYMBOL_GPL(nfnetlink_send);
113
114 int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
115 {
116 return netlink_unicast(nfnl, skb, pid, flags);
117 }
118 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
119
120 /* Process one complete nfnetlink message. */
121 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
122 {
123 const struct nfnl_callback *nc;
124 const struct nfnetlink_subsystem *ss;
125 int type, err;
126
127 if (security_netlink_recv(skb, CAP_NET_ADMIN))
128 return -EPERM;
129
130 /* All the messages must at least contain nfgenmsg */
131 if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
132 return 0;
133
134 type = nlh->nlmsg_type;
135 ss = nfnetlink_get_subsys(type);
136 if (!ss) {
137 #ifdef CONFIG_KMOD
138 nfnl_unlock();
139 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
140 nfnl_lock();
141 ss = nfnetlink_get_subsys(type);
142 if (!ss)
143 #endif
144 return -EINVAL;
145 }
146
147 nc = nfnetlink_find_client(type, ss);
148 if (!nc)
149 return -EINVAL;
150
151 {
152 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
153 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
154 u_int16_t attr_count = ss->cb[cb_id].attr_count;
155 struct nlattr *cda[attr_count+1];
156
157 if (likely(nlh->nlmsg_len >= min_len)) {
158 struct nlattr *attr = (void *)nlh + NLMSG_ALIGN(min_len);
159 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
160
161 err = nla_parse(cda, attr_count, attr, attrlen,
162 ss->cb[cb_id].policy);
163 if (err < 0)
164 return err;
165 } else
166 return -EINVAL;
167
168 return nc->call(nfnl, skb, nlh, cda);
169 }
170 }
171
172 static void nfnetlink_rcv(struct sk_buff *skb)
173 {
174 nfnl_lock();
175 netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
176 nfnl_unlock();
177 }
178
179 static void __exit nfnetlink_exit(void)
180 {
181 printk("Removing netfilter NETLINK layer.\n");
182 netlink_kernel_release(nfnl);
183 return;
184 }
185
186 static int __init nfnetlink_init(void)
187 {
188 printk("Netfilter messages via NETLINK v%s.\n", nfversion);
189
190 nfnl = netlink_kernel_create(&init_net, NETLINK_NETFILTER, NFNLGRP_MAX,
191 nfnetlink_rcv, NULL, THIS_MODULE);
192 if (!nfnl) {
193 printk(KERN_ERR "cannot initialize nfnetlink!\n");
194 return -1;
195 }
196
197 return 0;
198 }
199
200 module_init(nfnetlink_init);
201 module_exit(nfnetlink_exit);
202
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