tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
37MODULE_LICENSE("GPL");
38MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
39MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
40
41static char __initdata nfversion[] = "0.30";
42
43static struct sock *nfnl = NULL;
44static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
45static DEFINE_MUTEX(nfnl_mutex);
46
47static inline void nfnl_lock(void)
48{
49 mutex_lock(&nfnl_mutex);
50}
51
52static inline void nfnl_unlock(void)
53{
54 mutex_unlock(&nfnl_mutex);
55}
56
57int 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}
69EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
70
71int 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}
79EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
80
81static 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
91static inline const struct nfnl_callback *
92nfnetlink_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
102int nfnetlink_has_listeners(unsigned int group)
103{
104 return netlink_has_listeners(nfnl, group);
105}
106EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
107
108int 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}
112EXPORT_SYMBOL_GPL(nfnetlink_send);
113
114int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
115{
116 return netlink_unicast(nfnl, skb, pid, flags);
117}
118EXPORT_SYMBOL_GPL(nfnetlink_unicast);
119
120/* Process one complete nfnetlink message. */
121static 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
172static void nfnetlink_rcv(struct sk_buff *skb)
173{
174 nfnl_lock();
175 netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
176 nfnl_unlock();
177}
178
179static void __exit nfnetlink_exit(void)
180{
181 printk("Removing netfilter NETLINK layer.\n");
182 sock_release(nfnl->sk_socket);
183 return;
184}
185
186static 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
200module_init(nfnetlink_init);
201module_exit(nfnetlink_exit);