[linux-block.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 by Pablo Neira Ayuso <pablo@eurodev.net>
 *
 * 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 <linux/init.h>
#include <linux/spinlock.h>

#include <linux/netfilter.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";

#if 0
#define DEBUGP(format, args...)	\
		printk(KERN_DEBUG "%s(%d):%s(): " format, __FILE__, \
			__LINE__, __FUNCTION__, ## args)
#else
#define DEBUGP(format, args...)
#endif

static struct sock *nfnl = NULL;
static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
DECLARE_MUTEX(nfnl_sem);

void nfnl_lock(void)
{
	nfnl_shlock();
}

void nfnl_unlock(void)
{
	nfnl_shunlock();
}

int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
{
	DEBUGP("registering subsystem ID %u\n", n->subsys_id);

	nfnl_lock();
	if (subsys_table[n->subsys_id]) {
		nfnl_unlock();
		return -EBUSY;
	}
	subsys_table[n->subsys_id] = n;
	nfnl_unlock();

	return 0;
}

int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
{
	DEBUGP("unregistering subsystem ID %u\n", n->subsys_id);

	nfnl_lock();
	subsys_table[n->subsys_id] = NULL;
	nfnl_unlock();

	return 0;
}

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
	    || subsys_table[subsys_id] == NULL)
		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) {
		DEBUGP("msgtype %u >= %u, returning\n", type, 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);
}

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);
	}
}

/**
 * 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;
	u_int16_t attr_count;
	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);

	if (unlikely(cb_id >= subsys->cb_count)) {
		DEBUGP("msgtype %u >= %u, returning\n",
			cb_id, subsys->cb_count);
		return -EINVAL;
	}

	min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
	if (unlikely(nlh->nlmsg_len < min_len))
		return -EINVAL;

	attr_count = subsys->cb[cb_id].attr_count;
	memset(cda, 0, sizeof(struct nfattr *) * 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);

		while (NFA_OK(attr, attrlen)) {
			unsigned flavor = NFA_TYPE(attr);
			if (flavor) {
				if (flavor > attr_count)
					return -EINVAL;
				cda[flavor - 1] = attr;
			}
			attr = NFA_NEXT(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)
{
	gfp_t allocation = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
	int err = 0;

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

	return err;
}

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

/* Process one complete nfnetlink message. */
static int nfnetlink_rcv_msg(struct sk_buff *skb,
				    struct nlmsghdr *nlh, int *errp)
{
	struct nfnl_callback *nc;
	struct nfnetlink_subsystem *ss;
	int type, err = 0;

	DEBUGP("entered; subsys=%u, msgtype=%u\n",
		 NFNL_SUBSYS_ID(nlh->nlmsg_type),
		 NFNL_MSG_TYPE(nlh->nlmsg_type));

	if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
		DEBUGP("missing CAP_NET_ADMIN\n");
		*errp = -EPERM;
		return -1;
	}

	/* Only requests are handled by kernel now. */
	if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
		DEBUGP("received non-request message\n");
		return 0;
	}

	/* All the messages must at least contain nfgenmsg */
	if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg))) {
		DEBUGP("received message was too short\n");
		return 0;
	}

	type = nlh->nlmsg_type;
	ss = nfnetlink_get_subsys(type);
	if (!ss) {
#ifdef CONFIG_KMOD
		/* don't call nfnl_shunlock, since it would reenter
		 * with further packet processing */
		up(&nfnl_sem);
		request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
		nfnl_shlock();
		ss = nfnetlink_get_subsys(type);
		if (!ss)
#endif
			goto err_inval;
	}

	nc = nfnetlink_find_client(type, ss);
	if (!nc) {
		DEBUGP("unable to find client for type %d\n", type);
		goto err_inval;
	}

	{
		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)
			goto err_inval;

		DEBUGP("calling handler\n");
		err = nc->call(nfnl, skb, nlh, cda, errp);
		*errp = err;
		return err;
	}

err_inval:
	DEBUGP("returning -EINVAL\n");
	*errp = -EINVAL;
	return -1;
}

/* Process one packet of messages. */
static inline int nfnetlink_rcv_skb(struct sk_buff *skb)
{
	int err;
	struct nlmsghdr *nlh;

	while (skb->len >= NLMSG_SPACE(0)) {
		u32 rlen;

		nlh = (struct nlmsghdr *)skb->data;
		if (nlh->nlmsg_len < sizeof(struct nlmsghdr)
		    || skb->len < nlh->nlmsg_len)
			return 0;
		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
		if (rlen > skb->len)
			rlen = skb->len;
		if (nfnetlink_rcv_msg(skb, nlh, &err)) {
			if (!err)
				return -1;
			netlink_ack(skb, nlh, err);
		} else
			if (nlh->nlmsg_flags & NLM_F_ACK)
				netlink_ack(skb, nlh, 0);
		skb_pull(skb, rlen);
	}

	return 0;
}

static void nfnetlink_rcv(struct sock *sk, int len)
{
	do {
		struct sk_buff *skb;

		if (nfnl_shlock_nowait())
			return;

		while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
			if (nfnetlink_rcv_skb(skb)) {
				if (skb->len)
					skb_queue_head(&sk->sk_receive_queue,
						       skb);
				else
					kfree_skb(skb);
				break;
			}
			kfree_skb(skb);
		}

		/* don't call nfnl_shunlock, since it would reenter
		 * with further packet processing */
		up(&nfnl_sem);
	} while(nfnl && nfnl->sk_receive_queue.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);

EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
EXPORT_SYMBOL_GPL(nfnetlink_send);
EXPORT_SYMBOL_GPL(nfnetlink_unicast);
EXPORT_SYMBOL_GPL(nfattr_parse);
EXPORT_SYMBOL_GPL(__nfa_fill);
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>
	6	* (C) 2005 by Pablo Neira Ayuso <pablo@eurodev.net>
	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>
	31	#include <linux/init.h>
	32	#include <linux/spinlock.h>
	33
	34	#include <linux/netfilter.h>
	35	#include <linux/netlink.h>
	36	#include <linux/netfilter/nfnetlink.h>
	37
	38	MODULE_LICENSE("GPL");
4fdb3bb7 HW	39	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
4fdb3bb7 HW	40	MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
f9e815b3 HW	41
	42	static char __initdata nfversion[] = "0.30";
	43
	44	#if 0
0ab43f84 HW	45	#define DEBUGP(format, args...) \
	46	printk(KERN_DEBUG "%s(%d):%s(): " format, __FILE__, \
	47	__LINE__, __FUNCTION__, ## args)
f9e815b3 HW	48	#else
	49	#define DEBUGP(format, args...)
	50	#endif
	51
	52	static struct sock *nfnl = NULL;
	53	static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
	54	DECLARE_MUTEX(nfnl_sem);
	55
	56	void nfnl_lock(void)
	57	{
	58	nfnl_shlock();
	59	}
	60
	61	void nfnl_unlock(void)
	62	{
	63	nfnl_shunlock();
	64	}
	65
	66	int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
	67	{
	68	DEBUGP("registering subsystem ID %u\n", n->subsys_id);
	69
f9e815b3	70	nfnl_lock();
0ab43f84 HW	71	if (subsys_table[n->subsys_id]) {
	72	nfnl_unlock();
	73	return -EBUSY;
	74	}
f9e815b3 HW	75	subsys_table[n->subsys_id] = n;
	76	nfnl_unlock();
	77
	78	return 0;
	79	}
	80
	81	int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
	82	{
	83	DEBUGP("unregistering subsystem ID %u\n", n->subsys_id);
	84
	85	nfnl_lock();
	86	subsys_table[n->subsys_id] = NULL;
	87	nfnl_unlock();
	88
	89	return 0;
	90	}
	91
	92	static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
	93	{
	94	u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
	95
	96	if (subsys_id >= NFNL_SUBSYS_COUNT
	97	\|\| subsys_table[subsys_id] == NULL)
	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
f9e815b3 HW	108	if (cb_id >= ss->cb_count) {
	109	DEBUGP("msgtype %u >= %u, returning\n", type, ss->cb_count);
	110	return NULL;
	111	}
	112
	113	return &ss->cb[cb_id];
	114	}
	115
	116	void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
	117	const void *data)
	118	{
	119	struct nfattr *nfa;
	120	int size = NFA_LENGTH(attrlen);
	121
	122	nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
	123	nfa->nfa_type = attrtype;
	124	nfa->nfa_len = size;
	125	memcpy(NFA_DATA(nfa), data, attrlen);
080774a2	126	memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
f9e815b3 HW	127	}
f9e815b3 HW	128
a2506c04	129	void nfattr_parse(struct nfattr tb[], int maxattr, struct nfattr nfa, int len)
f9e815b3 HW	130	{
	131	memset(tb, 0, sizeof(struct nfattr ) maxattr);
	132
	133	while (NFA_OK(nfa, len)) {
ebe0bbf0	134	unsigned flavor = NFA_TYPE(nfa);
f9e815b3 HW	135	if (flavor && flavor <= maxattr)
	136	tb[flavor-1] = nfa;
	137	nfa = NFA_NEXT(nfa, len);
	138	}
f9e815b3 HW	139	}
	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	{
	153	int min_len;
927ccbcc HW	154	u_int16_t attr_count;
927ccbcc HW	155	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
f9e815b3	156
927ccbcc HW	157	if (unlikely(cb_id >= subsys->cb_count)) {
	158	DEBUGP("msgtype %u >= %u, returning\n",
	159	cb_id, subsys->cb_count);
	160	return -EINVAL;
	161	}
f9e815b3	162
3ebbe0cd	163	min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
a42827b7	164	if (unlikely(nlh->nlmsg_len < min_len))
f9e815b3 HW	165	return -EINVAL;
f9e815b3 HW	166
a42827b7 HW	167	attr_count = subsys->cb[cb_id].attr_count;
	168	memset(cda, 0, sizeof(struct nfattr ) attr_count);
	169
	170	/* check attribute lengths. */
	171	if (likely(nlh->nlmsg_len > min_len)) {
f9e815b3 HW	172	struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
	173	int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
	174
	175	while (NFA_OK(attr, attrlen)) {
ebe0bbf0	176	unsigned flavor = NFA_TYPE(attr);
f9e815b3	177	if (flavor) {
927ccbcc	178	if (flavor > attr_count)
f9e815b3 HW	179	return -EINVAL;
	180	cda[flavor - 1] = attr;
	181	}
	182	attr = NFA_NEXT(attr, attrlen);
	183	}
a42827b7 HW	184	}
	185
	186	/* implicit: if nlmsg_len == min_len, we return 0, and an empty
	187	* (zeroed) cda[] array. The message is valid, but empty. */
f9e815b3	188
601e68e1	189	return 0;
f9e815b3 HW	190	}
f9e815b3 HW	191
a2427692 PM	192	int nfnetlink_has_listeners(unsigned int group)
	193	{
	194	return netlink_has_listeners(nfnl, group);
	195	}
	196	EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
	197
f9e815b3 HW	198	int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
f9e815b3 HW	199	{
dd0fc66f	200	gfp_t allocation = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
f9e815b3 HW	201	int err = 0;
f9e815b3 HW	202
ac6d439d	203	NETLINK_CB(skb).dst_group = group;
f9e815b3 HW	204	if (echo)
	205	atomic_inc(&skb->users);
	206	netlink_broadcast(nfnl, skb, pid, group, allocation);
	207	if (echo)
	208	err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
	209
	210	return err;
	211	}
	212
	213	int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
	214	{
	215	return netlink_unicast(nfnl, skb, pid, flags);
	216	}
	217
	218	/* Process one complete nfnetlink message. */
858119e1	219	static int nfnetlink_rcv_msg(struct sk_buff *skb,
f9e815b3 HW	220	struct nlmsghdr nlh, int errp)
	221	{
	222	struct nfnl_callback *nc;
	223	struct nfnetlink_subsystem *ss;
	224	int type, err = 0;
	225
	226	DEBUGP("entered; subsys=%u, msgtype=%u\n",
	227	NFNL_SUBSYS_ID(nlh->nlmsg_type),
	228	NFNL_MSG_TYPE(nlh->nlmsg_type));
	229
c7bdb545	230	if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
37d2e7a2 HW	231	DEBUGP("missing CAP_NET_ADMIN\n");
	232	*errp = -EPERM;
	233	return -1;
	234	}
	235
f9e815b3 HW	236	/* Only requests are handled by kernel now. */
	237	if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
	238	DEBUGP("received non-request message\n");
	239	return 0;
	240	}
	241
	242	/* All the messages must at least contain nfgenmsg */
3ebbe0cd	243	if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg))) {
f9e815b3 HW	244	DEBUGP("received message was too short\n");
	245	return 0;
	246	}
	247
	248	type = nlh->nlmsg_type;
	249	ss = nfnetlink_get_subsys(type);
0ab43f84 HW	250	if (!ss) {
0ab43f84 HW	251	#ifdef CONFIG_KMOD
37d2e7a2 HW	252	/* don't call nfnl_shunlock, since it would reenter
	253	* with further packet processing */
	254	up(&nfnl_sem);
	255	request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
	256	nfnl_shlock();
	257	ss = nfnetlink_get_subsys(type);
0ab43f84 HW	258	if (!ss)
0ab43f84 HW	259	#endif
ed77de9f	260	goto err_inval;
0ab43f84	261	}
f9e815b3 HW	262
	263	nc = nfnetlink_find_client(type, ss);
	264	if (!nc) {
	265	DEBUGP("unable to find client for type %d\n", type);
	266	goto err_inval;
	267	}
	268
f9e815b3	269	{
601e68e1	270	u_int16_t attr_count =
927ccbcc HW	271	ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
927ccbcc HW	272	struct nfattr *cda[attr_count];
f9e815b3	273
927ccbcc	274	memset(cda, 0, sizeof(struct nfattr ) attr_count);
601e68e1	275
f9e815b3 HW	276	err = nfnetlink_check_attributes(ss, nlh, cda);
	277	if (err < 0)
	278	goto err_inval;
	279
0ab43f84	280	DEBUGP("calling handler\n");
f9e815b3 HW	281	err = nc->call(nfnl, skb, nlh, cda, errp);
	282	*errp = err;
	283	return err;
	284	}
	285
	286	err_inval:
0ab43f84	287	DEBUGP("returning -EINVAL\n");
f9e815b3 HW	288	*errp = -EINVAL;
	289	return -1;
	290	}
	291
	292	/* Process one packet of messages. */
	293	static inline int nfnetlink_rcv_skb(struct sk_buff *skb)
	294	{
	295	int err;
	296	struct nlmsghdr *nlh;
	297
	298	while (skb->len >= NLMSG_SPACE(0)) {
	299	u32 rlen;
	300
	301	nlh = (struct nlmsghdr *)skb->data;
	302	if (nlh->nlmsg_len < sizeof(struct nlmsghdr)
	303	\|\| skb->len < nlh->nlmsg_len)
	304	return 0;
	305	rlen = NLMSG_ALIGN(nlh->nlmsg_len);
	306	if (rlen > skb->len)
	307	rlen = skb->len;
	308	if (nfnetlink_rcv_msg(skb, nlh, &err)) {
	309	if (!err)
	310	return -1;
	311	netlink_ack(skb, nlh, err);
	312	} else
	313	if (nlh->nlmsg_flags & NLM_F_ACK)
	314	netlink_ack(skb, nlh, 0);
	315	skb_pull(skb, rlen);
	316	}
	317
	318	return 0;
	319	}
	320
	321	static void nfnetlink_rcv(struct sock *sk, int len)
	322	{
	323	do {
	324	struct sk_buff *skb;
	325
	326	if (nfnl_shlock_nowait())
	327	return;
	328
	329	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
	330	if (nfnetlink_rcv_skb(skb)) {
	331	if (skb->len)
	332	skb_queue_head(&sk->sk_receive_queue,
	333	skb);
	334	else
	335	kfree_skb(skb);
	336	break;
	337	}
	338	kfree_skb(skb);
	339	}
	340
0ab43f84 HW	341	/* don't call nfnl_shunlock, since it would reenter
0ab43f84 HW	342	* with further packet processing */
f9e815b3 HW	343	up(&nfnl_sem);
	344	} while(nfnl && nfnl->sk_receive_queue.qlen);
	345	}
	346
395dde20	347	static void __exit nfnetlink_exit(void)
f9e815b3 HW	348	{
	349	printk("Removing netfilter NETLINK layer.\n");
	350	sock_release(nfnl->sk_socket);
	351	return;
	352	}
	353
395dde20	354	static int __init nfnetlink_init(void)
f9e815b3 HW	355	{
	356	printk("Netfilter messages via NETLINK v%s.\n", nfversion);
	357
06628607	358	nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
601e68e1	359	nfnetlink_rcv, THIS_MODULE);
f9e815b3 HW	360	if (!nfnl) {
	361	printk(KERN_ERR "cannot initialize nfnetlink!\n");
	362	return -1;
	363	}
	364
	365	return 0;
	366	}
	367
	368	module_init(nfnetlink_init);
	369	module_exit(nfnetlink_exit);
	370
	371	EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
	372	EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
	373	EXPORT_SYMBOL_GPL(nfnetlink_send);
	374	EXPORT_SYMBOL_GPL(nfnetlink_unicast);
	375	EXPORT_SYMBOL_GPL(nfattr_parse);
	376	EXPORT_SYMBOL_GPL(__nfa_fill);