[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) 2005,2007 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/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";

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;
}

int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
{
	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)
		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))
		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)
{
	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;
}

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;

	if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
		*errp = -EPERM;
		return -1;
	}

	/* Only requests are handled by kernel now. */
	if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
		return 0;

	/* 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
			goto err_inval;
	}

	nc = nfnetlink_find_client(type, ss);
	if (!nc)
		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;

		err = nc->call(nfnl, skb, nlh, cda, errp);
		*errp = err;
		return err;
	}

err_inval:
	*errp = -EINVAL;
	return -1;
}

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);

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>
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 HW	32	#include <linux/init.h>
	33	#include <linux/spinlock.h>
	34
	35	#include <linux/netfilter.h>
	36	#include <linux/netlink.h>
	37	#include <linux/netfilter/nfnetlink.h>
	38
	39	MODULE_LICENSE("GPL");
4fdb3bb7 HW	40	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
4fdb3bb7 HW	41	MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
f9e815b3 HW	42
	43	static char __initdata nfversion[] = "0.30";
	44
f9e815b3 HW	45	static struct sock *nfnl = NULL;
f9e815b3 HW	46	static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
a3c5029c	47	static DEFINE_MUTEX(nfnl_mutex);
f9e815b3	48
a3c5029c	49	static void nfnl_lock(void)
f9e815b3	50	{
a3c5029c	51	mutex_lock(&nfnl_mutex);
f9e815b3 HW	52	}
f9e815b3 HW	53
a3c5029c	54	static int nfnl_trylock(void)
f9e815b3	55	{
a3c5029c PM	56	return !mutex_trylock(&nfnl_mutex);
	57	}
	58
	59	static void __nfnl_unlock(void)
	60	{
	61	mutex_unlock(&nfnl_mutex);
	62	}
	63
	64	static void nfnl_unlock(void)
	65	{
	66	mutex_unlock(&nfnl_mutex);
	67	if (nfnl->sk_receive_queue.qlen)
	68	nfnl->sk_data_ready(nfnl, 0);
f9e815b3 HW	69	}
	70
	71	int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
	72	{
f9e815b3	73	nfnl_lock();
0ab43f84 HW	74	if (subsys_table[n->subsys_id]) {
	75	nfnl_unlock();
	76	return -EBUSY;
	77	}
f9e815b3 HW	78	subsys_table[n->subsys_id] = n;
	79	nfnl_unlock();
	80
	81	return 0;
	82	}
	83
	84	int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
	85	{
f9e815b3 HW	86	nfnl_lock();
	87	subsys_table[n->subsys_id] = NULL;
	88	nfnl_unlock();
	89
	90	return 0;
	91	}
	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
	97	if (subsys_id >= NFNL_SUBSYS_COUNT
	98	\|\| subsys_table[subsys_id] == NULL)
	99	return NULL;
	100
	101	return subsys_table[subsys_id];
	102	}
	103
	104	static inline struct nfnl_callback *
	105	nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
	106	{
	107	u_int8_t cb_id = NFNL_MSG_TYPE(type);
601e68e1	108
67ca3966	109	if (cb_id >= ss->cb_count)
f9e815b3	110	return NULL;
f9e815b3 HW	111
	112	return &ss->cb[cb_id];
	113	}
	114
	115	void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
	116	const void *data)
	117	{
	118	struct nfattr *nfa;
	119	int size = NFA_LENGTH(attrlen);
	120
	121	nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
	122	nfa->nfa_type = attrtype;
	123	nfa->nfa_len = size;
	124	memcpy(NFA_DATA(nfa), data, attrlen);
080774a2	125	memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
f9e815b3 HW	126	}
f9e815b3 HW	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 HW	138	}
	139
	140	/**
	141	* nfnetlink_check_attributes - check and parse nfnetlink attributes
	142	*
	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
	146	*
	147	*/
	148	static int
	149	nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
	150	struct nlmsghdr nlh, struct nfattr cda[])
	151	{
	152	int min_len;
927ccbcc HW	153	u_int16_t attr_count;
927ccbcc HW	154	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
f9e815b3	155
67ca3966	156	if (unlikely(cb_id >= subsys->cb_count))
927ccbcc	157	return -EINVAL;
f9e815b3	158
3ebbe0cd	159	min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
a42827b7	160	if (unlikely(nlh->nlmsg_len < min_len))
f9e815b3 HW	161	return -EINVAL;
f9e815b3 HW	162
a42827b7 HW	163	attr_count = subsys->cb[cb_id].attr_count;
	164	memset(cda, 0, sizeof(struct nfattr ) attr_count);
	165
	166	/* check attribute lengths. */
	167	if (likely(nlh->nlmsg_len > min_len)) {
f9e815b3 HW	168	struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
	169	int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
	170
	171	while (NFA_OK(attr, attrlen)) {
ebe0bbf0	172	unsigned flavor = NFA_TYPE(attr);
f9e815b3	173	if (flavor) {
927ccbcc	174	if (flavor > attr_count)
f9e815b3 HW	175	return -EINVAL;
	176	cda[flavor - 1] = attr;
	177	}
	178	attr = NFA_NEXT(attr, attrlen);
	179	}
a42827b7 HW	180	}
	181
	182	/* implicit: if nlmsg_len == min_len, we return 0, and an empty
	183	* (zeroed) cda[] array. The message is valid, but empty. */
f9e815b3	184
601e68e1	185	return 0;
f9e815b3 HW	186	}
f9e815b3 HW	187
a2427692 PM	188	int nfnetlink_has_listeners(unsigned int group)
	189	{
	190	return netlink_has_listeners(nfnl, group);
	191	}
	192	EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
	193
f9e815b3 HW	194	int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
f9e815b3 HW	195	{
f9e815b3 HW	196	int err = 0;
f9e815b3 HW	197
ac6d439d	198	NETLINK_CB(skb).dst_group = group;
f9e815b3 HW	199	if (echo)
f9e815b3 HW	200	atomic_inc(&skb->users);
4498121c	201	netlink_broadcast(nfnl, skb, pid, group, gfp_any());
f9e815b3 HW	202	if (echo)
	203	err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
	204
	205	return err;
	206	}
	207
	208	int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
	209	{
	210	return netlink_unicast(nfnl, skb, pid, flags);
	211	}
	212
	213	/* Process one complete nfnetlink message. */
858119e1	214	static int nfnetlink_rcv_msg(struct sk_buff *skb,
f9e815b3 HW	215	struct nlmsghdr nlh, int errp)
	216	{
	217	struct nfnl_callback *nc;
	218	struct nfnetlink_subsystem *ss;
	219	int type, err = 0;
	220
c7bdb545	221	if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
37d2e7a2 HW	222	*errp = -EPERM;
	223	return -1;
	224	}
	225
f9e815b3	226	/* Only requests are handled by kernel now. */
67ca3966	227	if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
f9e815b3	228	return 0;
f9e815b3 HW	229
f9e815b3 HW	230	/* All the messages must at least contain nfgenmsg */
67ca3966	231	if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
f9e815b3	232	return 0;
f9e815b3 HW	233
	234	type = nlh->nlmsg_type;
	235	ss = nfnetlink_get_subsys(type);
0ab43f84 HW	236	if (!ss) {
0ab43f84 HW	237	#ifdef CONFIG_KMOD
a3c5029c	238	/* don't call nfnl_unlock, since it would reenter
37d2e7a2	239	* with further packet processing */
a3c5029c	240	__nfnl_unlock();
37d2e7a2	241	request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
a3c5029c	242	nfnl_lock();
37d2e7a2	243	ss = nfnetlink_get_subsys(type);
0ab43f84 HW	244	if (!ss)
0ab43f84 HW	245	#endif
ed77de9f	246	goto err_inval;
0ab43f84	247	}
f9e815b3 HW	248
f9e815b3 HW	249	nc = nfnetlink_find_client(type, ss);
67ca3966	250	if (!nc)
f9e815b3	251	goto err_inval;
f9e815b3	252
f9e815b3	253	{
601e68e1	254	u_int16_t attr_count =
927ccbcc HW	255	ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
927ccbcc HW	256	struct nfattr *cda[attr_count];
f9e815b3	257
927ccbcc	258	memset(cda, 0, sizeof(struct nfattr ) attr_count);
601e68e1	259
f9e815b3 HW	260	err = nfnetlink_check_attributes(ss, nlh, cda);
	261	if (err < 0)
	262	goto err_inval;
	263
	264	err = nc->call(nfnl, skb, nlh, cda, errp);
	265	*errp = err;
	266	return err;
	267	}
	268
	269	err_inval:
	270	*errp = -EINVAL;
	271	return -1;
	272	}
	273
f9e815b3 HW	274	static void nfnetlink_rcv(struct sock *sk, int len)
f9e815b3 HW	275	{
73c36186	276	unsigned int qlen = 0;
f9e815b3	277
73c36186	278	do {
a3c5029c	279	if (nfnl_trylock())
f9e815b3	280	return;
73c36186	281	netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg);
a3c5029c	282	__nfnl_unlock();
73c36186	283	} while (qlen);
f9e815b3 HW	284	}
f9e815b3 HW	285
395dde20	286	static void __exit nfnetlink_exit(void)
f9e815b3 HW	287	{
	288	printk("Removing netfilter NETLINK layer.\n");
	289	sock_release(nfnl->sk_socket);
	290	return;
	291	}
	292
395dde20	293	static int __init nfnetlink_init(void)
f9e815b3 HW	294	{
	295	printk("Netfilter messages via NETLINK v%s.\n", nfversion);
	296
06628607	297	nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
601e68e1	298	nfnetlink_rcv, THIS_MODULE);
f9e815b3 HW	299	if (!nfnl) {
	300	printk(KERN_ERR "cannot initialize nfnetlink!\n");
	301	return -1;
	302	}
	303
	304	return 0;
	305	}
	306
	307	module_init(nfnetlink_init);
	308	module_exit(nfnetlink_exit);
	309
	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);