[net-next-2.6.git] / net / netfilter / nfnetlink.c

/* Netfilter messages via netlink socket. Allows for user space
 * protocol helpers and general trouble making from userspace.
 *
 * (C) 2001 by Jay Schulist <jschlst@samba.org>,
 * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
 * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * Initial netfilter messages via netlink development funded and
 * generally made possible by Network Robots, Inc. (www.networkrobots.com)
 *
 * Further development of this code funded by Astaro AG (http://www.astaro.com)
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/fcntl.h>
#include <linux/skbuff.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <linux/init.h>

#include <linux/netlink.h>
#include <linux/netfilter/nfnetlink.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);

static char __initdata nfversion[] = "0.30";

static struct sock *nfnl = NULL;
static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
static DEFINE_MUTEX(nfnl_mutex);

static void nfnl_lock(void)
{
	mutex_lock(&nfnl_mutex);
}

static int nfnl_trylock(void)
{
	return !mutex_trylock(&nfnl_mutex);
}

static void __nfnl_unlock(void)
{
	mutex_unlock(&nfnl_mutex);
}

static void nfnl_unlock(void)
{
	mutex_unlock(&nfnl_mutex);
	if (nfnl->sk_receive_queue.qlen)
		nfnl->sk_data_ready(nfnl, 0);
}

int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
{
	nfnl_lock();
	if (subsys_table[n->subsys_id]) {
		nfnl_unlock();
		return -EBUSY;
	}
	subsys_table[n->subsys_id] = n;
	nfnl_unlock();

	return 0;
}
EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);

int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
{
	nfnl_lock();
	subsys_table[n->subsys_id] = NULL;
	nfnl_unlock();

	return 0;
}
EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);

static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
{
	u_int8_t subsys_id = NFNL_SUBSYS_ID(type);

	if (subsys_id >= NFNL_SUBSYS_COUNT)
		return NULL;

	return subsys_table[subsys_id];
}

static inline struct nfnl_callback *
nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
{
	u_int8_t cb_id = NFNL_MSG_TYPE(type);

	if (cb_id >= ss->cb_count)
		return NULL;

	return &ss->cb[cb_id];
}

void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
		const void *data)
{
	struct nfattr *nfa;
	int size = NFA_LENGTH(attrlen);

	nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
	nfa->nfa_type = attrtype;
	nfa->nfa_len  = size;
	memcpy(NFA_DATA(nfa), data, attrlen);
	memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
}
EXPORT_SYMBOL_GPL(__nfa_fill);

void nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
{
	memset(tb, 0, sizeof(struct nfattr *) * maxattr);

	while (NFA_OK(nfa, len)) {
		unsigned flavor = NFA_TYPE(nfa);
		if (flavor && flavor <= maxattr)
			tb[flavor-1] = nfa;
		nfa = NFA_NEXT(nfa, len);
	}
}
EXPORT_SYMBOL_GPL(nfattr_parse);

/**
 * nfnetlink_check_attributes - check and parse nfnetlink attributes
 *
 * subsys: nfnl subsystem for which this message is to be parsed
 * nlmsghdr: netlink message to be checked/parsed
 * cda: array of pointers, needs to be at least subsys->attr_count big
 *
 */
static int
nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
			   struct nlmsghdr *nlh, struct nfattr *cda[])
{
	int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
	u_int16_t attr_count = subsys->cb[cb_id].attr_count;

	/* check attribute lengths. */
	if (likely(nlh->nlmsg_len > min_len)) {
		struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
		int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
		nfattr_parse(cda, attr_count, attr, attrlen);
	}

	/* implicit: if nlmsg_len == min_len, we return 0, and an empty
	 * (zeroed) cda[] array. The message is valid, but empty. */

	return 0;
}

int nfnetlink_has_listeners(unsigned int group)
{
	return netlink_has_listeners(nfnl, group);
}
EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);

int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
{
	int err = 0;

	NETLINK_CB(skb).dst_group = group;
	if (echo)
		atomic_inc(&skb->users);
	netlink_broadcast(nfnl, skb, pid, group, gfp_any());
	if (echo)
		err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);

	return err;
}
EXPORT_SYMBOL_GPL(nfnetlink_send);

int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
{
	return netlink_unicast(nfnl, skb, pid, flags);
}
EXPORT_SYMBOL_GPL(nfnetlink_unicast);

/* Process one complete nfnetlink message. */
static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
	struct nfnl_callback *nc;
	struct nfnetlink_subsystem *ss;
	int type, err;

	if (security_netlink_recv(skb, CAP_NET_ADMIN))
		return -EPERM;

	/* All the messages must at least contain nfgenmsg */
	if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
		return 0;

	type = nlh->nlmsg_type;
	ss = nfnetlink_get_subsys(type);
	if (!ss) {
#ifdef CONFIG_KMOD
		/* don't call nfnl_unlock, since it would reenter
		 * with further packet processing */
		__nfnl_unlock();
		request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
		nfnl_lock();
		ss = nfnetlink_get_subsys(type);
		if (!ss)
#endif
			return -EINVAL;
	}

	nc = nfnetlink_find_client(type, ss);
	if (!nc)
		return -EINVAL;

	{
		u_int16_t attr_count =
			ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
		struct nfattr *cda[attr_count];

		memset(cda, 0, sizeof(struct nfattr *) * attr_count);

		err = nfnetlink_check_attributes(ss, nlh, cda);
		if (err < 0)
			return err;
		return nc->call(nfnl, skb, nlh, cda);
	}
}

static void nfnetlink_rcv(struct sock *sk, int len)
{
	unsigned int qlen = 0;

	do {
		if (nfnl_trylock())
			return;
		netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg);
		__nfnl_unlock();
	} while (qlen);
}

static void __exit nfnetlink_exit(void)
{
	printk("Removing netfilter NETLINK layer.\n");
	sock_release(nfnl->sk_socket);
	return;
}

static int __init nfnetlink_init(void)
{
	printk("Netfilter messages via NETLINK v%s.\n", nfversion);

	nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
				     nfnetlink_rcv, THIS_MODULE);
	if (!nfnl) {
		printk(KERN_ERR "cannot initialize nfnetlink!\n");
		return -1;
	}

	return 0;
}

module_init(nfnetlink_init);
module_exit(nfnetlink_exit);
Commit	Line	Data
f9e815b3 HW	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>
67ca3966	6	* (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
f9e815b3 HW	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
f9e815b3 HW	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>
f9e815b3 HW	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>
a3c5029c	31	#include <net/netlink.h>
f9e815b3	32	#include <linux/init.h>
f9e815b3	33
f9e815b3 HW	34	#include <linux/netlink.h>
	35	#include <linux/netfilter/nfnetlink.h>
	36
	37	MODULE_LICENSE("GPL");
4fdb3bb7 HW	38	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
4fdb3bb7 HW	39	MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
f9e815b3 HW	40
	41	static char __initdata nfversion[] = "0.30";
	42
f9e815b3 HW	43	static struct sock *nfnl = NULL;
f9e815b3 HW	44	static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
a3c5029c	45	static DEFINE_MUTEX(nfnl_mutex);
f9e815b3	46
a3c5029c	47	static void nfnl_lock(void)
f9e815b3	48	{
a3c5029c	49	mutex_lock(&nfnl_mutex);
f9e815b3 HW	50	}
f9e815b3 HW	51
a3c5029c	52	static int nfnl_trylock(void)
f9e815b3	53	{
a3c5029c PM	54	return !mutex_trylock(&nfnl_mutex);
	55	}
	56
	57	static void __nfnl_unlock(void)
	58	{
	59	mutex_unlock(&nfnl_mutex);
	60	}
	61
	62	static void nfnl_unlock(void)
	63	{
	64	mutex_unlock(&nfnl_mutex);
	65	if (nfnl->sk_receive_queue.qlen)
	66	nfnl->sk_data_ready(nfnl, 0);
f9e815b3 HW	67	}
	68
	69	int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
	70	{
f9e815b3	71	nfnl_lock();
0ab43f84 HW	72	if (subsys_table[n->subsys_id]) {
	73	nfnl_unlock();
	74	return -EBUSY;
	75	}
f9e815b3 HW	76	subsys_table[n->subsys_id] = n;
	77	nfnl_unlock();
	78
	79	return 0;
	80	}
f4bc177f	81	EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
f9e815b3 HW	82
	83	int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
	84	{
f9e815b3 HW	85	nfnl_lock();
	86	subsys_table[n->subsys_id] = NULL;
	87	nfnl_unlock();
	88
	89	return 0;
	90	}
f4bc177f	91	EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
f9e815b3 HW	92
	93	static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
	94	{
	95	u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
	96
ac0f1d98	97	if (subsys_id >= NFNL_SUBSYS_COUNT)
f9e815b3 HW	98	return NULL;
	99
	100	return subsys_table[subsys_id];
	101	}
	102
	103	static inline struct nfnl_callback *
	104	nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
	105	{
	106	u_int8_t cb_id = NFNL_MSG_TYPE(type);
601e68e1	107
67ca3966	108	if (cb_id >= ss->cb_count)
f9e815b3	109	return NULL;
f9e815b3 HW	110
	111	return &ss->cb[cb_id];
	112	}
	113
	114	void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
	115	const void *data)
	116	{
	117	struct nfattr *nfa;
	118	int size = NFA_LENGTH(attrlen);
	119
	120	nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
	121	nfa->nfa_type = attrtype;
	122	nfa->nfa_len = size;
	123	memcpy(NFA_DATA(nfa), data, attrlen);
080774a2	124	memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
f9e815b3	125	}
f4bc177f	126	EXPORT_SYMBOL_GPL(__nfa_fill);
f9e815b3	127
a2506c04	128	void nfattr_parse(struct nfattr tb[], int maxattr, struct nfattr nfa, int len)
f9e815b3 HW	129	{
	130	memset(tb, 0, sizeof(struct nfattr ) maxattr);
	131
	132	while (NFA_OK(nfa, len)) {
ebe0bbf0	133	unsigned flavor = NFA_TYPE(nfa);
f9e815b3 HW	134	if (flavor && flavor <= maxattr)
	135	tb[flavor-1] = nfa;
	136	nfa = NFA_NEXT(nfa, len);
	137	}
f9e815b3	138	}
f4bc177f	139	EXPORT_SYMBOL_GPL(nfattr_parse);
f9e815b3 HW	140
	141	/**
	142	* nfnetlink_check_attributes - check and parse nfnetlink attributes
	143	*
	144	* subsys: nfnl subsystem for which this message is to be parsed
	145	* nlmsghdr: netlink message to be checked/parsed
	146	* cda: array of pointers, needs to be at least subsys->attr_count big
	147	*
	148	*/
	149	static int
	150	nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
	151	struct nlmsghdr nlh, struct nfattr cda[])
	152	{
d9e6d029	153	int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
927ccbcc	154	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
ac6d141d	155	u_int16_t attr_count = subsys->cb[cb_id].attr_count;
a42827b7 HW	156
	157	/* check attribute lengths. */
	158	if (likely(nlh->nlmsg_len > min_len)) {
f9e815b3 HW	159	struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
f9e815b3 HW	160	int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
ac6d141d	161	nfattr_parse(cda, attr_count, attr, attrlen);
a42827b7 HW	162	}
	163
	164	/* implicit: if nlmsg_len == min_len, we return 0, and an empty
	165	* (zeroed) cda[] array. The message is valid, but empty. */
f9e815b3	166
601e68e1	167	return 0;
f9e815b3 HW	168	}
f9e815b3 HW	169
a2427692 PM	170	int nfnetlink_has_listeners(unsigned int group)
	171	{
	172	return netlink_has_listeners(nfnl, group);
	173	}
	174	EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
	175
f9e815b3 HW	176	int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
f9e815b3 HW	177	{
f9e815b3 HW	178	int err = 0;
f9e815b3 HW	179
ac6d439d	180	NETLINK_CB(skb).dst_group = group;
f9e815b3 HW	181	if (echo)
f9e815b3 HW	182	atomic_inc(&skb->users);
4498121c	183	netlink_broadcast(nfnl, skb, pid, group, gfp_any());
f9e815b3 HW	184	if (echo)
	185	err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
	186
	187	return err;
	188	}
f4bc177f	189	EXPORT_SYMBOL_GPL(nfnetlink_send);
f9e815b3 HW	190
	191	int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
	192	{
	193	return netlink_unicast(nfnl, skb, pid, flags);
	194	}
f4bc177f	195	EXPORT_SYMBOL_GPL(nfnetlink_unicast);
f9e815b3 HW	196
f9e815b3 HW	197	/* Process one complete nfnetlink message. */
1d00a4eb	198	static int nfnetlink_rcv_msg(struct sk_buff skb, struct nlmsghdr nlh)
f9e815b3 HW	199	{
	200	struct nfnl_callback *nc;
	201	struct nfnetlink_subsystem *ss;
1d00a4eb	202	int type, err;
f9e815b3	203
1d00a4eb TG	204	if (security_netlink_recv(skb, CAP_NET_ADMIN))
1d00a4eb TG	205	return -EPERM;
37d2e7a2	206
f9e815b3	207	/* All the messages must at least contain nfgenmsg */
67ca3966	208	if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
f9e815b3	209	return 0;
f9e815b3 HW	210
	211	type = nlh->nlmsg_type;
	212	ss = nfnetlink_get_subsys(type);
0ab43f84 HW	213	if (!ss) {
0ab43f84 HW	214	#ifdef CONFIG_KMOD
a3c5029c	215	/* don't call nfnl_unlock, since it would reenter
37d2e7a2	216	* with further packet processing */
a3c5029c	217	__nfnl_unlock();
37d2e7a2	218	request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
a3c5029c	219	nfnl_lock();
37d2e7a2	220	ss = nfnetlink_get_subsys(type);
0ab43f84 HW	221	if (!ss)
0ab43f84 HW	222	#endif
1d00a4eb	223	return -EINVAL;
0ab43f84	224	}
f9e815b3 HW	225
f9e815b3 HW	226	nc = nfnetlink_find_client(type, ss);
67ca3966	227	if (!nc)
1d00a4eb	228	return -EINVAL;
f9e815b3	229
f9e815b3	230	{
601e68e1	231	u_int16_t attr_count =
927ccbcc HW	232	ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
927ccbcc HW	233	struct nfattr *cda[attr_count];
f9e815b3	234
927ccbcc	235	memset(cda, 0, sizeof(struct nfattr ) attr_count);
601e68e1	236
f9e815b3 HW	237	err = nfnetlink_check_attributes(ss, nlh, cda);
f9e815b3 HW	238	if (err < 0)
1d00a4eb TG	239	return err;
1d00a4eb TG	240	return nc->call(nfnl, skb, nlh, cda);
f9e815b3	241	}
f9e815b3 HW	242	}
f9e815b3 HW	243
f9e815b3 HW	244	static void nfnetlink_rcv(struct sock *sk, int len)
f9e815b3 HW	245	{
73c36186	246	unsigned int qlen = 0;
f9e815b3	247
73c36186	248	do {
a3c5029c	249	if (nfnl_trylock())
f9e815b3	250	return;
73c36186	251	netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg);
a3c5029c	252	__nfnl_unlock();
73c36186	253	} while (qlen);
f9e815b3 HW	254	}
f9e815b3 HW	255
395dde20	256	static void __exit nfnetlink_exit(void)
f9e815b3 HW	257	{
	258	printk("Removing netfilter NETLINK layer.\n");
	259	sock_release(nfnl->sk_socket);
	260	return;
	261	}
	262
395dde20	263	static int __init nfnetlink_init(void)
f9e815b3 HW	264	{
	265	printk("Netfilter messages via NETLINK v%s.\n", nfversion);
	266
06628607	267	nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
601e68e1	268	nfnetlink_rcv, THIS_MODULE);
f9e815b3 HW	269	if (!nfnl) {
	270	printk(KERN_ERR "cannot initialize nfnetlink!\n");
	271	return -1;
	272	}
	273
	274	return 0;
	275	}
	276
	277	module_init(nfnetlink_init);
	278	module_exit(nfnetlink_exit);