[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;
	struct nf_ct_ext *ext = ct->ext;

	for (i = 0; i < NF_CT_EXT_NUM; i++) {
		if (!__nf_ct_ext_exist(ext, 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;
	size_t alloc_size;

	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;
	alloc_size = t->alloc_size;
	rcu_read_unlock();

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

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

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

static void __nf_ct_ext_free_rcu(struct rcu_head *head)
{
	struct nf_ct_ext *ext = container_of(head, struct nf_ct_ext, rcu);
	kfree(ext);
}

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

	/* Conntrack must not be confirmed to avoid races on reallocation. */
	NF_CT_ASSERT(!nf_ct_is_confirmed(ct));

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

	if (__nf_ct_ext_exist(old, id))
		return NULL;

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

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

	new = __krealloc(old, newlen, gfp);
	if (!new)
		return NULL;

	if (new != old) {
		for (i = 0; i < NF_CT_EXT_NUM; i++) {
			if (!__nf_ct_ext_exist(old, 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 *)old + old->offset[i]);
			rcu_read_unlock();
		}
		call_rcu(&old->rcu, __nf_ct_ext_free_rcu);
		ct->ext = new;
	}

	new->offset[id] = newoff;
	new->len = newlen;
	memset((void *)new + newoff, 0, newlen - newoff);
	return (void *)new + 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);
	rcu_barrier(); /* Wait for completion of call_rcu()'s */
}
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;
ee92d378	26	struct nf_ct_ext *ext = ct->ext;
ecfab2c9 YK	27
ecfab2c9 YK	28	for (i = 0; i < NF_CT_EXT_NUM; i++) {
ee92d378	29	if (!__nf_ct_ext_exist(ext, i))
ecfab2c9 YK	30	continue;
	31
	32	rcu_read_lock();
	33	t = rcu_dereference(nf_ct_ext_types[i]);
	34
	35	/* Here the nf_ct_ext_type might have been unregisterd.
	36	* I.e., it has responsible to cleanup private
	37	* area in all conntracks when it is unregisterd.
	38	*/
	39	if (t && t->destroy)
	40	t->destroy(ct);
	41	rcu_read_unlock();
	42	}
	43	}
	44	EXPORT_SYMBOL(__nf_ct_ext_destroy);
	45
	46	static void *
	47	nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp)
	48	{
019f692e	49	unsigned int off, len;
ecfab2c9	50	struct nf_ct_ext_type *t;
15cdeada	51	size_t alloc_size;
ecfab2c9 YK	52
	53	rcu_read_lock();
	54	t = rcu_dereference(nf_ct_ext_types[id]);
	55	BUG_ON(t == NULL);
	56	off = ALIGN(sizeof(struct nf_ct_ext), t->align);
	57	len = off + t->len;
15cdeada	58	alloc_size = t->alloc_size;
ecfab2c9 YK	59	rcu_read_unlock();
ecfab2c9 YK	60
15cdeada	61	*ext = kzalloc(alloc_size, gfp);
ecfab2c9 YK	62	if (!*ext)
	63	return NULL;
	64
	65	(*ext)->offset[id] = off;
	66	(*ext)->len = len;
ecfab2c9 YK	67
	68	return (void )(ext) + off;
	69	}
	70
68b80f11 PM	71	static void __nf_ct_ext_free_rcu(struct rcu_head *head)
	72	{
	73	struct nf_ct_ext *ext = container_of(head, struct nf_ct_ext, rcu);
	74	kfree(ext);
	75	}
	76
ecfab2c9 YK	77	void __nf_ct_ext_add(struct nf_conn ct, enum nf_ct_ext_id id, gfp_t gfp)
ecfab2c9 YK	78	{
ee92d378	79	struct nf_ct_ext old, new;
ecfab2c9 YK	80	int i, newlen, newoff;
	81	struct nf_ct_ext_type *t;
	82
55871d04 PM	83	/* Conntrack must not be confirmed to avoid races on reallocation. */
	84	NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
	85
ee92d378 CG	86	old = ct->ext;
ee92d378 CG	87	if (!old)
ecfab2c9 YK	88	return nf_ct_ext_create(&ct->ext, id, gfp);
ecfab2c9 YK	89
ee92d378	90	if (__nf_ct_ext_exist(old, id))
ecfab2c9 YK	91	return NULL;
	92
	93	rcu_read_lock();
	94	t = rcu_dereference(nf_ct_ext_types[id]);
	95	BUG_ON(t == NULL);
	96
ee92d378	97	newoff = ALIGN(old->len, t->align);
ecfab2c9 YK	98	newlen = newoff + t->len;
	99	rcu_read_unlock();
	100
ee92d378	101	new = __krealloc(old, newlen, gfp);
31d8519c PE	102	if (!new)
31d8519c PE	103	return NULL;
ecfab2c9	104
ee92d378	105	if (new != old) {
ecfab2c9	106	for (i = 0; i < NF_CT_EXT_NUM; i++) {
ee92d378	107	if (!__nf_ct_ext_exist(old, i))
ecfab2c9 YK	108	continue;
	109
	110	rcu_read_lock();
	111	t = rcu_dereference(nf_ct_ext_types[i]);
	112	if (t && t->move)
86577c66	113	t->move((void *)new + new->offset[i],
ee92d378	114	(void *)old + old->offset[i]);
ecfab2c9 YK	115	rcu_read_unlock();
ecfab2c9 YK	116	}
ee92d378	117	call_rcu(&old->rcu, __nf_ct_ext_free_rcu);
ecfab2c9 YK	118	ct->ext = new;
	119	}
	120
6c64825b PM	121	new->offset[id] = newoff;
	122	new->len = newlen;
	123	memset((void *)new + newoff, 0, newlen - newoff);
	124	return (void *)new + newoff;
ecfab2c9 YK	125	}
	126	EXPORT_SYMBOL(__nf_ct_ext_add);
	127
	128	static void update_alloc_size(struct nf_ct_ext_type *type)
	129	{
	130	int i, j;
	131	struct nf_ct_ext_type t1, t2;
	132	enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1;
	133
	134	/* unnecessary to update all types */
	135	if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) {
	136	min = type->id;
	137	max = type->id;
	138	}
	139
	140	/* This assumes that extended areas in conntrack for the types
	141	whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */
	142	for (i = min; i <= max; i++) {
	143	t1 = nf_ct_ext_types[i];
	144	if (!t1)
	145	continue;
	146
	147	t1->alloc_size = sizeof(struct nf_ct_ext)
	148	+ ALIGN(sizeof(struct nf_ct_ext), t1->align)
	149	+ t1->len;
	150	for (j = 0; j < NF_CT_EXT_NUM; j++) {
	151	t2 = nf_ct_ext_types[j];
	152	if (t2 == NULL \|\| t2 == t1 \|\|
	153	(t2->flags & NF_CT_EXT_F_PREALLOC) == 0)
	154	continue;
	155
	156	t1->alloc_size = ALIGN(t1->alloc_size, t2->align)
	157	+ t2->len;
	158	}
ecfab2c9 YK	159	}
	160	}
	161
	162	/* This MUST be called in process context. */
	163	int nf_ct_extend_register(struct nf_ct_ext_type *type)
	164	{
	165	int ret = 0;
	166
	167	mutex_lock(&nf_ct_ext_type_mutex);
	168	if (nf_ct_ext_types[type->id]) {
	169	ret = -EBUSY;
	170	goto out;
	171	}
	172
	173	/* This ensures that nf_ct_ext_create() can allocate enough area
	174	before updating alloc_size */
	175	type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align)
	176	+ type->len;
	177	rcu_assign_pointer(nf_ct_ext_types[type->id], type);
	178	update_alloc_size(type);
	179	out:
	180	mutex_unlock(&nf_ct_ext_type_mutex);
	181	return ret;
	182	}
	183	EXPORT_SYMBOL_GPL(nf_ct_extend_register);
	184
	185	/* This MUST be called in process context. */
	186	void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
	187	{
	188	mutex_lock(&nf_ct_ext_type_mutex);
	189	rcu_assign_pointer(nf_ct_ext_types[type->id], NULL);
	190	update_alloc_size(type);
	191	mutex_unlock(&nf_ct_ext_type_mutex);
308ff823	192	rcu_barrier(); /* Wait for completion of call_rcu()'s */
ecfab2c9 YK	193	}
ecfab2c9 YK	194	EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);