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 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(struct nfnetlink_subsystem *n)
72 if (subsys_table[n->subsys_id]) {
76 subsys_table[n->subsys_id] = n;
82 int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
85 subsys_table[n->subsys_id] = NULL;
91 static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
93 u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
95 if (subsys_id >= NFNL_SUBSYS_COUNT)
98 return subsys_table[subsys_id];
101 static inline struct nfnl_callback *
102 nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
104 u_int8_t cb_id = NFNL_MSG_TYPE(type);
106 if (cb_id >= ss->cb_count)
109 return &ss->cb[cb_id];
112 void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
116 int size = NFA_LENGTH(attrlen);
118 nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
119 nfa->nfa_type = attrtype;
121 memcpy(NFA_DATA(nfa), data, attrlen);
122 memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
125 void nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
127 memset(tb, 0, sizeof(struct nfattr *) * maxattr);
129 while (NFA_OK(nfa, len)) {
130 unsigned flavor = NFA_TYPE(nfa);
131 if (flavor && flavor <= maxattr)
133 nfa = NFA_NEXT(nfa, len);
138 * nfnetlink_check_attributes - check and parse nfnetlink attributes
140 * subsys: nfnl subsystem for which this message is to be parsed
141 * nlmsghdr: netlink message to be checked/parsed
142 * cda: array of pointers, needs to be at least subsys->attr_count big
146 nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
147 struct nlmsghdr *nlh, struct nfattr *cda[])
149 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
150 u_int16_t attr_count;
151 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
153 attr_count = subsys->cb[cb_id].attr_count;
154 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
156 /* check attribute lengths. */
157 if (likely(nlh->nlmsg_len > min_len)) {
158 struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
159 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
161 while (NFA_OK(attr, attrlen)) {
162 unsigned flavor = NFA_TYPE(attr);
164 if (flavor > attr_count)
166 cda[flavor - 1] = attr;
168 attr = NFA_NEXT(attr, attrlen);
172 /* implicit: if nlmsg_len == min_len, we return 0, and an empty
173 * (zeroed) cda[] array. The message is valid, but empty. */
178 int nfnetlink_has_listeners(unsigned int group)
180 return netlink_has_listeners(nfnl, group);
182 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
184 int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
188 NETLINK_CB(skb).dst_group = group;
190 atomic_inc(&skb->users);
191 netlink_broadcast(nfnl, skb, pid, group, gfp_any());
193 err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
198 int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
200 return netlink_unicast(nfnl, skb, pid, flags);
203 /* Process one complete nfnetlink message. */
204 static int nfnetlink_rcv_msg(struct sk_buff *skb,
205 struct nlmsghdr *nlh, int *errp)
207 struct nfnl_callback *nc;
208 struct nfnetlink_subsystem *ss;
211 if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
216 /* Only requests are handled by kernel now. */
217 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
220 /* All the messages must at least contain nfgenmsg */
221 if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
224 type = nlh->nlmsg_type;
225 ss = nfnetlink_get_subsys(type);
228 /* don't call nfnl_unlock, since it would reenter
229 * with further packet processing */
231 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
233 ss = nfnetlink_get_subsys(type);
239 nc = nfnetlink_find_client(type, ss);
244 u_int16_t attr_count =
245 ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
246 struct nfattr *cda[attr_count];
248 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
250 err = nfnetlink_check_attributes(ss, nlh, cda);
254 err = nc->call(nfnl, skb, nlh, cda, errp);
264 static void nfnetlink_rcv(struct sock *sk, int len)
266 unsigned int qlen = 0;
271 netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg);
276 static void __exit nfnetlink_exit(void)
278 printk("Removing netfilter NETLINK layer.\n");
279 sock_release(nfnl->sk_socket);
283 static int __init nfnetlink_init(void)
285 printk("Netfilter messages via NETLINK v%s.\n", nfversion);
287 nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
288 nfnetlink_rcv, THIS_MODULE);
290 printk(KERN_ERR "cannot initialize nfnetlink!\n");
297 module_init(nfnetlink_init);
298 module_exit(nfnetlink_exit);
300 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
301 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
302 EXPORT_SYMBOL_GPL(nfnetlink_send);
303 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
304 EXPORT_SYMBOL_GPL(nfattr_parse);
305 EXPORT_SYMBOL_GPL(__nfa_fill);