1 /* Netfilter messages via netlink socket. Allows for user space
2 * protocol helpers and general trouble making from userspace.
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>
8 * Initial netfilter messages via netlink development funded and
9 * generally made possible by Network Robots, Inc. (www.networkrobots.com)
11 * Further development of this code funded by Astaro AG (http://www.astaro.com)
13 * This software may be used and distributed according to the terms
14 * of the GNU General Public License, incorporated herein by reference.
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>
31 #include <net/netlink.h>
32 #include <linux/init.h>
34 #include <linux/netlink.h>
35 #include <linux/netfilter/nfnetlink.h>
37 MODULE_LICENSE("GPL");
38 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
39 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
41 static char __initdata nfversion[] = "0.30";
43 static struct sock *nfnl = NULL;
44 static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
45 static DEFINE_MUTEX(nfnl_mutex);
47 static void nfnl_lock(void)
49 mutex_lock(&nfnl_mutex);
52 static int nfnl_trylock(void)
54 return !mutex_trylock(&nfnl_mutex);
57 static void __nfnl_unlock(void)
59 mutex_unlock(&nfnl_mutex);
62 static void nfnl_unlock(void)
64 mutex_unlock(&nfnl_mutex);
65 if (nfnl->sk_receive_queue.qlen)
66 nfnl->sk_data_ready(nfnl, 0);
69 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
72 if (subsys_table[n->subsys_id]) {
76 subsys_table[n->subsys_id] = n;
81 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
83 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
86 subsys_table[n->subsys_id] = NULL;
91 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
93 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
95 u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
97 if (subsys_id >= NFNL_SUBSYS_COUNT)
100 return subsys_table[subsys_id];
103 static inline const struct nfnl_callback *
104 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss)
106 u_int8_t cb_id = NFNL_MSG_TYPE(type);
108 if (cb_id >= ss->cb_count)
111 return &ss->cb[cb_id];
115 * nfnetlink_check_attributes - check and parse nfnetlink attributes
117 * subsys: nfnl subsystem for which this message is to be parsed
118 * nlmsghdr: netlink message to be checked/parsed
119 * cda: array of pointers, needs to be at least subsys->attr_count+1 big
123 nfnetlink_check_attributes(const struct nfnetlink_subsystem *subsys,
124 struct nlmsghdr *nlh, struct nlattr *cda[])
126 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
127 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
128 u_int16_t attr_count = subsys->cb[cb_id].attr_count;
130 /* check attribute lengths. */
131 if (likely(nlh->nlmsg_len > min_len)) {
132 struct nlattr *attr = (void *)nlh + NLMSG_ALIGN(min_len);
133 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
134 nla_parse(cda, attr_count, attr, attrlen, NULL);
137 /* implicit: if nlmsg_len == min_len, we return 0, and an empty
138 * (zeroed) cda[] array. The message is valid, but empty. */
143 int nfnetlink_has_listeners(unsigned int group)
145 return netlink_has_listeners(nfnl, group);
147 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
149 int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
151 return nlmsg_notify(nfnl, skb, pid, group, echo, gfp_any());
153 EXPORT_SYMBOL_GPL(nfnetlink_send);
155 int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
157 return netlink_unicast(nfnl, skb, pid, flags);
159 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
161 /* Process one complete nfnetlink message. */
162 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
164 const struct nfnl_callback *nc;
165 const struct nfnetlink_subsystem *ss;
168 if (security_netlink_recv(skb, CAP_NET_ADMIN))
171 /* All the messages must at least contain nfgenmsg */
172 if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
175 type = nlh->nlmsg_type;
176 ss = nfnetlink_get_subsys(type);
179 /* don't call nfnl_unlock, since it would reenter
180 * with further packet processing */
182 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
184 ss = nfnetlink_get_subsys(type);
190 nc = nfnetlink_find_client(type, ss);
195 u_int16_t attr_count =
196 ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
197 struct nlattr *cda[attr_count+1];
199 memset(cda, 0, sizeof(struct nlattr *) * attr_count);
201 err = nfnetlink_check_attributes(ss, nlh, cda);
204 return nc->call(nfnl, skb, nlh, cda);
208 static void nfnetlink_rcv(struct sock *sk, int len)
210 unsigned int qlen = 0;
215 qlen = netlink_run_queue(sk, qlen, nfnetlink_rcv_msg);
220 static void __exit nfnetlink_exit(void)
222 printk("Removing netfilter NETLINK layer.\n");
223 sock_release(nfnl->sk_socket);
227 static int __init nfnetlink_init(void)
229 printk("Netfilter messages via NETLINK v%s.\n", nfversion);
231 nfnl = netlink_kernel_create(&init_net, NETLINK_NETFILTER, NFNLGRP_MAX,
232 nfnetlink_rcv, NULL, THIS_MODULE);
234 printk(KERN_ERR "cannot initialize nfnetlink!\n");
241 module_init(nfnetlink_init);
242 module_exit(nfnetlink_exit);