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>
33 #include <linux/spinlock.h>
35 #include <linux/netfilter.h>
36 #include <linux/netlink.h>
37 #include <linux/netfilter/nfnetlink.h>
39 MODULE_LICENSE("GPL");
40 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
41 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
43 static char __initdata nfversion[] = "0.30";
45 static struct sock *nfnl = NULL;
46 static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
47 static DEFINE_MUTEX(nfnl_mutex);
49 static void nfnl_lock(void)
51 mutex_lock(&nfnl_mutex);
54 static int nfnl_trylock(void)
56 return !mutex_trylock(&nfnl_mutex);
59 static void __nfnl_unlock(void)
61 mutex_unlock(&nfnl_mutex);
64 static void nfnl_unlock(void)
66 mutex_unlock(&nfnl_mutex);
67 if (nfnl->sk_receive_queue.qlen)
68 nfnl->sk_data_ready(nfnl, 0);
71 int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
74 if (subsys_table[n->subsys_id]) {
78 subsys_table[n->subsys_id] = n;
84 int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
87 subsys_table[n->subsys_id] = NULL;
93 static inline 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
98 || subsys_table[subsys_id] == NULL)
101 return subsys_table[subsys_id];
104 static inline struct nfnl_callback *
105 nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
107 u_int8_t cb_id = NFNL_MSG_TYPE(type);
109 if (cb_id >= ss->cb_count)
112 return &ss->cb[cb_id];
115 void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
119 int size = NFA_LENGTH(attrlen);
121 nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
122 nfa->nfa_type = attrtype;
124 memcpy(NFA_DATA(nfa), data, attrlen);
125 memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
128 void nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
130 memset(tb, 0, sizeof(struct nfattr *) * maxattr);
132 while (NFA_OK(nfa, len)) {
133 unsigned flavor = NFA_TYPE(nfa);
134 if (flavor && flavor <= maxattr)
136 nfa = NFA_NEXT(nfa, len);
141 * nfnetlink_check_attributes - check and parse nfnetlink attributes
143 * subsys: nfnl subsystem for which this message is to be parsed
144 * nlmsghdr: netlink message to be checked/parsed
145 * cda: array of pointers, needs to be at least subsys->attr_count big
149 nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
150 struct nlmsghdr *nlh, struct nfattr *cda[])
153 u_int16_t attr_count;
154 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
156 if (unlikely(cb_id >= subsys->cb_count))
159 min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
160 if (unlikely(nlh->nlmsg_len < min_len))
163 attr_count = subsys->cb[cb_id].attr_count;
164 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
166 /* check attribute lengths. */
167 if (likely(nlh->nlmsg_len > min_len)) {
168 struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
169 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
171 while (NFA_OK(attr, attrlen)) {
172 unsigned flavor = NFA_TYPE(attr);
174 if (flavor > attr_count)
176 cda[flavor - 1] = attr;
178 attr = NFA_NEXT(attr, attrlen);
182 /* implicit: if nlmsg_len == min_len, we return 0, and an empty
183 * (zeroed) cda[] array. The message is valid, but empty. */
188 int nfnetlink_has_listeners(unsigned int group)
190 return netlink_has_listeners(nfnl, group);
192 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
194 int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
198 NETLINK_CB(skb).dst_group = group;
200 atomic_inc(&skb->users);
201 netlink_broadcast(nfnl, skb, pid, group, gfp_any());
203 err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
208 int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
210 return netlink_unicast(nfnl, skb, pid, flags);
213 /* Process one complete nfnetlink message. */
214 static int nfnetlink_rcv_msg(struct sk_buff *skb,
215 struct nlmsghdr *nlh, int *errp)
217 struct nfnl_callback *nc;
218 struct nfnetlink_subsystem *ss;
221 if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
226 /* Only requests are handled by kernel now. */
227 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
230 /* All the messages must at least contain nfgenmsg */
231 if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
234 type = nlh->nlmsg_type;
235 ss = nfnetlink_get_subsys(type);
238 /* don't call nfnl_unlock, since it would reenter
239 * with further packet processing */
241 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
243 ss = nfnetlink_get_subsys(type);
249 nc = nfnetlink_find_client(type, ss);
254 u_int16_t attr_count =
255 ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
256 struct nfattr *cda[attr_count];
258 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
260 err = nfnetlink_check_attributes(ss, nlh, cda);
264 err = nc->call(nfnl, skb, nlh, cda, errp);
274 static void nfnetlink_rcv(struct sock *sk, int len)
276 unsigned int qlen = 0;
281 netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg);
286 static void __exit nfnetlink_exit(void)
288 printk("Removing netfilter NETLINK layer.\n");
289 sock_release(nfnl->sk_socket);
293 static int __init nfnetlink_init(void)
295 printk("Netfilter messages via NETLINK v%s.\n", nfversion);
297 nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
298 nfnetlink_rcv, THIS_MODULE);
300 printk(KERN_ERR "cannot initialize nfnetlink!\n");
307 module_init(nfnetlink_init);
308 module_exit(nfnetlink_exit);
310 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
311 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
312 EXPORT_SYMBOL_GPL(nfnetlink_send);
313 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
314 EXPORT_SYMBOL_GPL(nfattr_parse);
315 EXPORT_SYMBOL_GPL(__nfa_fill);