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 by Pablo Neira Ayuso <pablo@eurodev.net>
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";
46 #define DEBUGP(format, args...) \
47 printk(KERN_DEBUG "%s(%d):%s(): " format, __FILE__, \
48 __LINE__, __FUNCTION__, ## args)
50 #define DEBUGP(format, args...)
53 static struct sock *nfnl = NULL;
54 static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
55 static DEFINE_MUTEX(nfnl_mutex);
57 static void nfnl_lock(void)
59 mutex_lock(&nfnl_mutex);
62 static int nfnl_trylock(void)
64 return !mutex_trylock(&nfnl_mutex);
67 static void __nfnl_unlock(void)
69 mutex_unlock(&nfnl_mutex);
72 static void nfnl_unlock(void)
74 mutex_unlock(&nfnl_mutex);
75 if (nfnl->sk_receive_queue.qlen)
76 nfnl->sk_data_ready(nfnl, 0);
79 int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
81 DEBUGP("registering subsystem ID %u\n", n->subsys_id);
84 if (subsys_table[n->subsys_id]) {
88 subsys_table[n->subsys_id] = n;
94 int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
96 DEBUGP("unregistering subsystem ID %u\n", n->subsys_id);
99 subsys_table[n->subsys_id] = NULL;
105 static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
107 u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
109 if (subsys_id >= NFNL_SUBSYS_COUNT
110 || subsys_table[subsys_id] == NULL)
113 return subsys_table[subsys_id];
116 static inline struct nfnl_callback *
117 nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
119 u_int8_t cb_id = NFNL_MSG_TYPE(type);
121 if (cb_id >= ss->cb_count) {
122 DEBUGP("msgtype %u >= %u, returning\n", type, ss->cb_count);
126 return &ss->cb[cb_id];
129 void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
133 int size = NFA_LENGTH(attrlen);
135 nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
136 nfa->nfa_type = attrtype;
138 memcpy(NFA_DATA(nfa), data, attrlen);
139 memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
142 void nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
144 memset(tb, 0, sizeof(struct nfattr *) * maxattr);
146 while (NFA_OK(nfa, len)) {
147 unsigned flavor = NFA_TYPE(nfa);
148 if (flavor && flavor <= maxattr)
150 nfa = NFA_NEXT(nfa, len);
155 * nfnetlink_check_attributes - check and parse nfnetlink attributes
157 * subsys: nfnl subsystem for which this message is to be parsed
158 * nlmsghdr: netlink message to be checked/parsed
159 * cda: array of pointers, needs to be at least subsys->attr_count big
163 nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
164 struct nlmsghdr *nlh, struct nfattr *cda[])
167 u_int16_t attr_count;
168 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
170 if (unlikely(cb_id >= subsys->cb_count)) {
171 DEBUGP("msgtype %u >= %u, returning\n",
172 cb_id, subsys->cb_count);
176 min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
177 if (unlikely(nlh->nlmsg_len < min_len))
180 attr_count = subsys->cb[cb_id].attr_count;
181 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
183 /* check attribute lengths. */
184 if (likely(nlh->nlmsg_len > min_len)) {
185 struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
186 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
188 while (NFA_OK(attr, attrlen)) {
189 unsigned flavor = NFA_TYPE(attr);
191 if (flavor > attr_count)
193 cda[flavor - 1] = attr;
195 attr = NFA_NEXT(attr, attrlen);
199 /* implicit: if nlmsg_len == min_len, we return 0, and an empty
200 * (zeroed) cda[] array. The message is valid, but empty. */
205 int nfnetlink_has_listeners(unsigned int group)
207 return netlink_has_listeners(nfnl, group);
209 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
211 int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
215 NETLINK_CB(skb).dst_group = group;
217 atomic_inc(&skb->users);
218 netlink_broadcast(nfnl, skb, pid, group, gfp_any());
220 err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
225 int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
227 return netlink_unicast(nfnl, skb, pid, flags);
230 /* Process one complete nfnetlink message. */
231 static int nfnetlink_rcv_msg(struct sk_buff *skb,
232 struct nlmsghdr *nlh, int *errp)
234 struct nfnl_callback *nc;
235 struct nfnetlink_subsystem *ss;
238 DEBUGP("entered; subsys=%u, msgtype=%u\n",
239 NFNL_SUBSYS_ID(nlh->nlmsg_type),
240 NFNL_MSG_TYPE(nlh->nlmsg_type));
242 if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
243 DEBUGP("missing CAP_NET_ADMIN\n");
248 /* Only requests are handled by kernel now. */
249 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
250 DEBUGP("received non-request message\n");
254 /* All the messages must at least contain nfgenmsg */
255 if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg))) {
256 DEBUGP("received message was too short\n");
260 type = nlh->nlmsg_type;
261 ss = nfnetlink_get_subsys(type);
264 /* don't call nfnl_unlock, since it would reenter
265 * with further packet processing */
267 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
269 ss = nfnetlink_get_subsys(type);
275 nc = nfnetlink_find_client(type, ss);
277 DEBUGP("unable to find client for type %d\n", type);
282 u_int16_t attr_count =
283 ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
284 struct nfattr *cda[attr_count];
286 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
288 err = nfnetlink_check_attributes(ss, nlh, cda);
292 DEBUGP("calling handler\n");
293 err = nc->call(nfnl, skb, nlh, cda, errp);
299 DEBUGP("returning -EINVAL\n");
304 static void nfnetlink_rcv(struct sock *sk, int len)
306 unsigned int qlen = 0;
311 netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg);
316 static void __exit nfnetlink_exit(void)
318 printk("Removing netfilter NETLINK layer.\n");
319 sock_release(nfnl->sk_socket);
323 static int __init nfnetlink_init(void)
325 printk("Netfilter messages via NETLINK v%s.\n", nfversion);
327 nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
328 nfnetlink_rcv, THIS_MODULE);
330 printk(KERN_ERR "cannot initialize nfnetlink!\n");
337 module_init(nfnetlink_init);
338 module_exit(nfnetlink_exit);
340 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
341 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
342 EXPORT_SYMBOL_GPL(nfnetlink_send);
343 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
344 EXPORT_SYMBOL_GPL(nfattr_parse);
345 EXPORT_SYMBOL_GPL(__nfa_fill);