[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 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/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/sched.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_ALIGN(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_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 inline 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));

	/* 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_LENGTH(NLMSG_ALIGN(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
		if (cap_raised(NETLINK_CB(skb).eff_cap, CAP_NET_ADMIN)) {
			/* 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;
	}

	if (nc->cap_required && 
	    !cap_raised(NETLINK_CB(skb).eff_cap, nc->cap_required)) {
		DEBUGP("permission denied for type %d\n", type);
		*errp = -EPERM;
		return -1;
	}

	{
		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
	17	#include <linux/config.h>
	18	#include <linux/module.h>
	19	#include <linux/types.h>
	20	#include <linux/socket.h>
	21	#include <linux/kernel.h>
	22	#include <linux/major.h>
	23	#include <linux/sched.h>
	24	#include <linux/timer.h>
	25	#include <linux/string.h>
	26	#include <linux/sockios.h>
	27	#include <linux/net.h>
	28	#include <linux/fcntl.h>
	29	#include <linux/skbuff.h>
	30	#include <asm/uaccess.h>
	31	#include <asm/system.h>
	32	#include <net/sock.h>
	33	#include <linux/init.h>
	34	#include <linux/spinlock.h>
	35
	36	#include <linux/netfilter.h>
	37	#include <linux/netlink.h>
	38	#include <linux/netfilter/nfnetlink.h>
	39
	40	MODULE_LICENSE("GPL");
4fdb3bb7 HW	41	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
4fdb3bb7 HW	42	MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
f9e815b3 HW	43
	44	static char __initdata nfversion[] = "0.30";
	45
	46	#if 0
0ab43f84 HW	47	#define DEBUGP(format, args...) \
	48	printk(KERN_DEBUG "%s(%d):%s(): " format, __FILE__, \
	49	__LINE__, __FUNCTION__, ## args)
f9e815b3 HW	50	#else
	51	#define DEBUGP(format, args...)
	52	#endif
	53
	54	static struct sock *nfnl = NULL;
	55	static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
	56	DECLARE_MUTEX(nfnl_sem);
	57
	58	void nfnl_lock(void)
	59	{
	60	nfnl_shlock();
	61	}
	62
	63	void nfnl_unlock(void)
	64	{
	65	nfnl_shunlock();
	66	}
	67
	68	int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
	69	{
	70	DEBUGP("registering subsystem ID %u\n", n->subsys_id);
	71
f9e815b3	72	nfnl_lock();
0ab43f84 HW	73	if (subsys_table[n->subsys_id]) {
	74	nfnl_unlock();
	75	return -EBUSY;
	76	}
f9e815b3 HW	77	subsys_table[n->subsys_id] = n;
	78	nfnl_unlock();
	79
	80	return 0;
	81	}
	82
	83	int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
	84	{
	85	DEBUGP("unregistering subsystem ID %u\n", n->subsys_id);
	86
	87	nfnl_lock();
	88	subsys_table[n->subsys_id] = NULL;
	89	nfnl_unlock();
	90
	91	return 0;
	92	}
	93
	94	static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
	95	{
	96	u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
	97
	98	if (subsys_id >= NFNL_SUBSYS_COUNT
	99	\|\| subsys_table[subsys_id] == NULL)
	100	return NULL;
	101
	102	return subsys_table[subsys_id];
	103	}
	104
	105	static inline struct nfnl_callback *
	106	nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
	107	{
	108	u_int8_t cb_id = NFNL_MSG_TYPE(type);
	109
	110	if (cb_id >= ss->cb_count) {
	111	DEBUGP("msgtype %u >= %u, returning\n", type, ss->cb_count);
	112	return NULL;
	113	}
	114
	115	return &ss->cb[cb_id];
	116	}
	117
	118	void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
	119	const void *data)
	120	{
	121	struct nfattr *nfa;
	122	int size = NFA_LENGTH(attrlen);
	123
	124	nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
	125	nfa->nfa_type = attrtype;
	126	nfa->nfa_len = size;
	127	memcpy(NFA_DATA(nfa), data, attrlen);
080774a2	128	memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
f9e815b3 HW	129	}
f9e815b3 HW	130
a2506c04	131	void nfattr_parse(struct nfattr tb[], int maxattr, struct nfattr nfa, int len)
f9e815b3 HW	132	{
	133	memset(tb, 0, sizeof(struct nfattr ) maxattr);
	134
	135	while (NFA_OK(nfa, len)) {
ebe0bbf0	136	unsigned flavor = NFA_TYPE(nfa);
f9e815b3 HW	137	if (flavor && flavor <= maxattr)
	138	tb[flavor-1] = nfa;
	139	nfa = NFA_NEXT(nfa, len);
	140	}
f9e815b3 HW	141	}
	142
	143	/**
	144	* nfnetlink_check_attributes - check and parse nfnetlink attributes
	145	*
	146	* subsys: nfnl subsystem for which this message is to be parsed
	147	* nlmsghdr: netlink message to be checked/parsed
	148	* cda: array of pointers, needs to be at least subsys->attr_count big
	149	*
	150	*/
	151	static int
	152	nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
	153	struct nlmsghdr nlh, struct nfattr cda[])
	154	{
	155	int min_len;
927ccbcc HW	156	u_int16_t attr_count;
927ccbcc HW	157	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
f9e815b3	158
927ccbcc HW	159	if (unlikely(cb_id >= subsys->cb_count)) {
	160	DEBUGP("msgtype %u >= %u, returning\n",
	161	cb_id, subsys->cb_count);
	162	return -EINVAL;
	163	}
f9e815b3	164
f9e815b3	165	min_len = NLMSG_ALIGN(sizeof(struct nfgenmsg));
a42827b7	166	if (unlikely(nlh->nlmsg_len < min_len))
f9e815b3 HW	167	return -EINVAL;
f9e815b3 HW	168
a42827b7 HW	169	attr_count = subsys->cb[cb_id].attr_count;
	170	memset(cda, 0, sizeof(struct nfattr ) attr_count);
	171
	172	/* check attribute lengths. */
	173	if (likely(nlh->nlmsg_len > min_len)) {
f9e815b3 HW	174	struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
	175	int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
	176
	177	while (NFA_OK(attr, attrlen)) {
ebe0bbf0	178	unsigned flavor = NFA_TYPE(attr);
f9e815b3	179	if (flavor) {
927ccbcc	180	if (flavor > attr_count)
f9e815b3 HW	181	return -EINVAL;
	182	cda[flavor - 1] = attr;
	183	}
	184	attr = NFA_NEXT(attr, attrlen);
	185	}
a42827b7 HW	186	}
	187
	188	/* implicit: if nlmsg_len == min_len, we return 0, and an empty
	189	* (zeroed) cda[] array. The message is valid, but empty. */
f9e815b3 HW	190
	191	return 0;
	192	}
	193
	194	int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
	195	{
dd0fc66f	196	gfp_t allocation = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
f9e815b3 HW	197	int err = 0;
f9e815b3 HW	198
ac6d439d	199	NETLINK_CB(skb).dst_group = group;
f9e815b3 HW	200	if (echo)
	201	atomic_inc(&skb->users);
	202	netlink_broadcast(nfnl, skb, pid, group, allocation);
	203	if (echo)
	204	err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
	205
	206	return err;
	207	}
	208
	209	int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
	210	{
	211	return netlink_unicast(nfnl, skb, pid, flags);
	212	}
	213
	214	/* Process one complete nfnetlink message. */
	215	static inline int nfnetlink_rcv_msg(struct sk_buff *skb,
	216	struct nlmsghdr nlh, int errp)
	217	{
	218	struct nfnl_callback *nc;
	219	struct nfnetlink_subsystem *ss;
	220	int type, err = 0;
	221
	222	DEBUGP("entered; subsys=%u, msgtype=%u\n",
	223	NFNL_SUBSYS_ID(nlh->nlmsg_type),
	224	NFNL_MSG_TYPE(nlh->nlmsg_type));
	225
	226	/* Only requests are handled by kernel now. */
	227	if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
	228	DEBUGP("received non-request message\n");
	229	return 0;
	230	}
	231
	232	/* All the messages must at least contain nfgenmsg */
	233	if (nlh->nlmsg_len <
	234	NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg)))) {
	235	DEBUGP("received message was too short\n");
	236	return 0;
	237	}
	238
	239	type = nlh->nlmsg_type;
	240	ss = nfnetlink_get_subsys(type);
0ab43f84 HW	241	if (!ss) {
0ab43f84 HW	242	#ifdef CONFIG_KMOD
ed77de9f HW	243	if (cap_raised(NETLINK_CB(skb).eff_cap, CAP_NET_ADMIN)) {
	244	/* don't call nfnl_shunlock, since it would reenter
	245	* with further packet processing */
	246	up(&nfnl_sem);
	247	request_module("nfnetlink-subsys-%d",
	248	NFNL_SUBSYS_ID(type));
	249	nfnl_shlock();
	250	ss = nfnetlink_get_subsys(type);
	251	}
0ab43f84 HW	252	if (!ss)
0ab43f84 HW	253	#endif
ed77de9f	254	goto err_inval;
0ab43f84	255	}
f9e815b3 HW	256
	257	nc = nfnetlink_find_client(type, ss);
	258	if (!nc) {
	259	DEBUGP("unable to find client for type %d\n", type);
	260	goto err_inval;
	261	}
	262
	263	if (nc->cap_required &&
	264	!cap_raised(NETLINK_CB(skb).eff_cap, nc->cap_required)) {
	265	DEBUGP("permission denied for type %d\n", type);
	266	*errp = -EPERM;
	267	return -1;
	268	}
	269
	270	{
927ccbcc HW	271	u_int16_t attr_count =
	272	ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
	273	struct nfattr *cda[attr_count];
f9e815b3	274
927ccbcc	275	memset(cda, 0, sizeof(struct nfattr ) attr_count);
f9e815b3 HW	276
	277	err = nfnetlink_check_attributes(ss, nlh, cda);
	278	if (err < 0)
	279	goto err_inval;
	280
0ab43f84	281	DEBUGP("calling handler\n");
f9e815b3 HW	282	err = nc->call(nfnl, skb, nlh, cda, errp);
	283	*errp = err;
	284	return err;
	285	}
	286
	287	err_inval:
0ab43f84	288	DEBUGP("returning -EINVAL\n");
f9e815b3 HW	289	*errp = -EINVAL;
	290	return -1;
	291	}
	292
	293	/* Process one packet of messages. */
	294	static inline int nfnetlink_rcv_skb(struct sk_buff *skb)
	295	{
	296	int err;
	297	struct nlmsghdr *nlh;
	298
	299	while (skb->len >= NLMSG_SPACE(0)) {
	300	u32 rlen;
	301
	302	nlh = (struct nlmsghdr *)skb->data;
	303	if (nlh->nlmsg_len < sizeof(struct nlmsghdr)
	304	\|\| skb->len < nlh->nlmsg_len)
	305	return 0;
	306	rlen = NLMSG_ALIGN(nlh->nlmsg_len);
	307	if (rlen > skb->len)
	308	rlen = skb->len;
	309	if (nfnetlink_rcv_msg(skb, nlh, &err)) {
	310	if (!err)
	311	return -1;
	312	netlink_ack(skb, nlh, err);
	313	} else
	314	if (nlh->nlmsg_flags & NLM_F_ACK)
	315	netlink_ack(skb, nlh, 0);
	316	skb_pull(skb, rlen);
	317	}
	318
	319	return 0;
	320	}
	321
	322	static void nfnetlink_rcv(struct sock *sk, int len)
	323	{
	324	do {
	325	struct sk_buff *skb;
	326
	327	if (nfnl_shlock_nowait())
	328	return;
	329
	330	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
	331	if (nfnetlink_rcv_skb(skb)) {
	332	if (skb->len)
	333	skb_queue_head(&sk->sk_receive_queue,
	334	skb);
	335	else
	336	kfree_skb(skb);
	337	break;
	338	}
	339	kfree_skb(skb);
	340	}
	341
0ab43f84 HW	342	/* don't call nfnl_shunlock, since it would reenter
0ab43f84 HW	343	* with further packet processing */
f9e815b3 HW	344	up(&nfnl_sem);
	345	} while(nfnl && nfnl->sk_receive_queue.qlen);
	346	}
	347
395dde20	348	static void __exit nfnetlink_exit(void)
f9e815b3 HW	349	{
	350	printk("Removing netfilter NETLINK layer.\n");
	351	sock_release(nfnl->sk_socket);
	352	return;
	353	}
	354
395dde20	355	static int __init nfnetlink_init(void)
f9e815b3 HW	356	{
	357	printk("Netfilter messages via NETLINK v%s.\n", nfversion);
	358
06628607 PM	359	nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
06628607 PM	360	nfnetlink_rcv, THIS_MODULE);
f9e815b3 HW	361	if (!nfnl) {
	362	printk(KERN_ERR "cannot initialize nfnetlink!\n");
	363	return -1;
	364	}
	365
	366	return 0;
	367	}
	368
	369	module_init(nfnetlink_init);
	370	module_exit(nfnetlink_exit);
	371
	372	EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
	373	EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
	374	EXPORT_SYMBOL_GPL(nfnetlink_send);
	375	EXPORT_SYMBOL_GPL(nfnetlink_unicast);
	376	EXPORT_SYMBOL_GPL(nfattr_parse);
	377	EXPORT_SYMBOL_GPL(__nfa_fill);