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

/* Structure dynamic extension infrastructure
 * Copyright (C) 2004 Rusty Russell IBM Corporation
 * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
 * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <net/netfilter/nf_conntrack_extend.h>

static struct nf_ct_ext_type *nf_ct_ext_types[NF_CT_EXT_NUM];
static DEFINE_MUTEX(nf_ct_ext_type_mutex);

void __nf_ct_ext_destroy(struct nf_conn *ct)
{
	unsigned int i;
	struct nf_ct_ext_type *t;

	for (i = 0; i < NF_CT_EXT_NUM; i++) {
		if (!nf_ct_ext_exist(ct, i))
			continue;

		rcu_read_lock();
		t = rcu_dereference(nf_ct_ext_types[i]);

		/* Here the nf_ct_ext_type might have been unregisterd.
		 * I.e., it has responsible to cleanup private
		 * area in all conntracks when it is unregisterd.
		 */
		if (t && t->destroy)
			t->destroy(ct);
		rcu_read_unlock();
	}
}
EXPORT_SYMBOL(__nf_ct_ext_destroy);

static void *
nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp)
{
	unsigned int off, len;
	struct nf_ct_ext_type *t;

	rcu_read_lock();
	t = rcu_dereference(nf_ct_ext_types[id]);
	BUG_ON(t == NULL);
	off = ALIGN(sizeof(struct nf_ct_ext), t->align);
	len = off + t->len;
	rcu_read_unlock();

	*ext = kzalloc(t->alloc_size, gfp);
	if (!*ext)
		return NULL;

	(*ext)->offset[id] = off;
	(*ext)->len = len;

	return (void *)(*ext) + off;
}

void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
{
	struct nf_ct_ext *new;
	int i, newlen, newoff;
	struct nf_ct_ext_type *t;

	if (!ct->ext)
		return nf_ct_ext_create(&ct->ext, id, gfp);

	if (nf_ct_ext_exist(ct, id))
		return NULL;

	rcu_read_lock();
	t = rcu_dereference(nf_ct_ext_types[id]);
	BUG_ON(t == NULL);

	newoff = ALIGN(ct->ext->len, t->align);
	newlen = newoff + t->len;
	rcu_read_unlock();

	if (newlen >= ksize(ct->ext)) {
		new = kmalloc(newlen, gfp);
		if (!new)
			return NULL;

		memcpy(new, ct->ext, ct->ext->len);

		for (i = 0; i < NF_CT_EXT_NUM; i++) {
			if (!nf_ct_ext_exist(ct, i))
				continue;

			rcu_read_lock();
			t = rcu_dereference(nf_ct_ext_types[i]);
			if (t && t->move)
				t->move((void *)new + new->offset[i],
					(void *)ct->ext + ct->ext->offset[i]);
			rcu_read_unlock();
		}
		kfree(ct->ext);
		ct->ext = new;
	}

	ct->ext->offset[id] = newoff;
	ct->ext->len = newlen;
	memset((void *)ct->ext + newoff, 0, newlen - newoff);
	return (void *)ct->ext + newoff;
}
EXPORT_SYMBOL(__nf_ct_ext_add);

static void update_alloc_size(struct nf_ct_ext_type *type)
{
	int i, j;
	struct nf_ct_ext_type *t1, *t2;
	enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1;

	/* unnecessary to update all types */
	if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) {
		min = type->id;
		max = type->id;
	}

	/* This assumes that extended areas in conntrack for the types
	   whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */
	for (i = min; i <= max; i++) {
		t1 = nf_ct_ext_types[i];
		if (!t1)
			continue;

		t1->alloc_size = sizeof(struct nf_ct_ext)
				 + ALIGN(sizeof(struct nf_ct_ext), t1->align)
				 + t1->len;
		for (j = 0; j < NF_CT_EXT_NUM; j++) {
			t2 = nf_ct_ext_types[j];
			if (t2 == NULL || t2 == t1 ||
			    (t2->flags & NF_CT_EXT_F_PREALLOC) == 0)
				continue;

			t1->alloc_size = ALIGN(t1->alloc_size, t2->align)
					 + t2->len;
		}
	}
}

/* This MUST be called in process context. */
int nf_ct_extend_register(struct nf_ct_ext_type *type)
{
	int ret = 0;

	mutex_lock(&nf_ct_ext_type_mutex);
	if (nf_ct_ext_types[type->id]) {
		ret = -EBUSY;
		goto out;
	}

	/* This ensures that nf_ct_ext_create() can allocate enough area
	   before updating alloc_size */
	type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align)
			   + type->len;
	rcu_assign_pointer(nf_ct_ext_types[type->id], type);
	update_alloc_size(type);
out:
	mutex_unlock(&nf_ct_ext_type_mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(nf_ct_extend_register);

/* This MUST be called in process context. */
void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
{
	mutex_lock(&nf_ct_ext_type_mutex);
	rcu_assign_pointer(nf_ct_ext_types[type->id], NULL);
	update_alloc_size(type);
	mutex_unlock(&nf_ct_ext_type_mutex);
	synchronize_rcu();
}
EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);
Commit	Line	Data
ecfab2c9 YK	1	/* Structure dynamic extension infrastructure
	2	* Copyright (C) 2004 Rusty Russell IBM Corporation
	3	* Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
	4	* Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11	#include <linux/kernel.h>
	12	#include <linux/module.h>
	13	#include <linux/mutex.h>
	14	#include <linux/rcupdate.h>
	15	#include <linux/slab.h>
	16	#include <linux/skbuff.h>
	17	#include <net/netfilter/nf_conntrack_extend.h>
	18
	19	static struct nf_ct_ext_type *nf_ct_ext_types[NF_CT_EXT_NUM];
	20	static DEFINE_MUTEX(nf_ct_ext_type_mutex);
	21
ecfab2c9 YK	22	void __nf_ct_ext_destroy(struct nf_conn *ct)
	23	{
	24	unsigned int i;
	25	struct nf_ct_ext_type *t;
	26
	27	for (i = 0; i < NF_CT_EXT_NUM; i++) {
	28	if (!nf_ct_ext_exist(ct, i))
	29	continue;
	30
	31	rcu_read_lock();
	32	t = rcu_dereference(nf_ct_ext_types[i]);
	33
	34	/* Here the nf_ct_ext_type might have been unregisterd.
	35	* I.e., it has responsible to cleanup private
	36	* area in all conntracks when it is unregisterd.
	37	*/
	38	if (t && t->destroy)
	39	t->destroy(ct);
	40	rcu_read_unlock();
	41	}
	42	}
	43	EXPORT_SYMBOL(__nf_ct_ext_destroy);
	44
	45	static void *
	46	nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp)
	47	{
019f692e	48	unsigned int off, len;
ecfab2c9 YK	49	struct nf_ct_ext_type *t;
	50
	51	rcu_read_lock();
	52	t = rcu_dereference(nf_ct_ext_types[id]);
	53	BUG_ON(t == NULL);
	54	off = ALIGN(sizeof(struct nf_ct_ext), t->align);
	55	len = off + t->len;
ecfab2c9 YK	56	rcu_read_unlock();
ecfab2c9 YK	57
019f692e	58	*ext = kzalloc(t->alloc_size, gfp);
ecfab2c9 YK	59	if (!*ext)
	60	return NULL;
	61
	62	(*ext)->offset[id] = off;
	63	(*ext)->len = len;
ecfab2c9 YK	64
	65	return (void )(ext) + off;
	66	}
	67
	68	void __nf_ct_ext_add(struct nf_conn ct, enum nf_ct_ext_id id, gfp_t gfp)
	69	{
	70	struct nf_ct_ext *new;
	71	int i, newlen, newoff;
	72	struct nf_ct_ext_type *t;
	73
	74	if (!ct->ext)
	75	return nf_ct_ext_create(&ct->ext, id, gfp);
	76
	77	if (nf_ct_ext_exist(ct, id))
	78	return NULL;
	79
	80	rcu_read_lock();
	81	t = rcu_dereference(nf_ct_ext_types[id]);
	82	BUG_ON(t == NULL);
	83
	84	newoff = ALIGN(ct->ext->len, t->align);
	85	newlen = newoff + t->len;
	86	rcu_read_unlock();
	87
019f692e	88	if (newlen >= ksize(ct->ext)) {
ecfab2c9 YK	89	new = kmalloc(newlen, gfp);
	90	if (!new)
	91	return NULL;
	92
	93	memcpy(new, ct->ext, ct->ext->len);
	94
	95	for (i = 0; i < NF_CT_EXT_NUM; i++) {
	96	if (!nf_ct_ext_exist(ct, i))
	97	continue;
	98
	99	rcu_read_lock();
	100	t = rcu_dereference(nf_ct_ext_types[i]);
	101	if (t && t->move)
86577c66 PM	102	t->move((void *)new + new->offset[i],
86577c66 PM	103	(void *)ct->ext + ct->ext->offset[i]);
ecfab2c9 YK	104	rcu_read_unlock();
	105	}
	106	kfree(ct->ext);
ecfab2c9 YK	107	ct->ext = new;
	108	}
	109
	110	ct->ext->offset[id] = newoff;
	111	ct->ext->len = newlen;
	112	memset((void *)ct->ext + newoff, 0, newlen - newoff);
	113	return (void *)ct->ext + newoff;
	114	}
	115	EXPORT_SYMBOL(__nf_ct_ext_add);
	116
	117	static void update_alloc_size(struct nf_ct_ext_type *type)
	118	{
	119	int i, j;
	120	struct nf_ct_ext_type t1, t2;
	121	enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1;
	122
	123	/* unnecessary to update all types */
	124	if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) {
	125	min = type->id;
	126	max = type->id;
	127	}
	128
	129	/* This assumes that extended areas in conntrack for the types
	130	whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */
	131	for (i = min; i <= max; i++) {
	132	t1 = nf_ct_ext_types[i];
	133	if (!t1)
	134	continue;
	135
	136	t1->alloc_size = sizeof(struct nf_ct_ext)
	137	+ ALIGN(sizeof(struct nf_ct_ext), t1->align)
	138	+ t1->len;
	139	for (j = 0; j < NF_CT_EXT_NUM; j++) {
	140	t2 = nf_ct_ext_types[j];
	141	if (t2 == NULL \|\| t2 == t1 \|\|
	142	(t2->flags & NF_CT_EXT_F_PREALLOC) == 0)
	143	continue;
	144
	145	t1->alloc_size = ALIGN(t1->alloc_size, t2->align)
	146	+ t2->len;
	147	}
ecfab2c9 YK	148	}
	149	}
	150
	151	/* This MUST be called in process context. */
	152	int nf_ct_extend_register(struct nf_ct_ext_type *type)
	153	{
	154	int ret = 0;
	155
	156	mutex_lock(&nf_ct_ext_type_mutex);
	157	if (nf_ct_ext_types[type->id]) {
	158	ret = -EBUSY;
	159	goto out;
	160	}
	161
	162	/* This ensures that nf_ct_ext_create() can allocate enough area
	163	before updating alloc_size */
	164	type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align)
	165	+ type->len;
	166	rcu_assign_pointer(nf_ct_ext_types[type->id], type);
	167	update_alloc_size(type);
	168	out:
	169	mutex_unlock(&nf_ct_ext_type_mutex);
	170	return ret;
	171	}
	172	EXPORT_SYMBOL_GPL(nf_ct_extend_register);
	173
	174	/* This MUST be called in process context. */
	175	void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
	176	{
	177	mutex_lock(&nf_ct_ext_type_mutex);
	178	rcu_assign_pointer(nf_ct_ext_types[type->id], NULL);
	179	update_alloc_size(type);
	180	mutex_unlock(&nf_ct_ext_type_mutex);
	181	synchronize_rcu();
	182	}
	183	EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);