[mirror_ubuntu-artful-kernel.git] / net / netfilter / nft_set_bitmap.c

/*
 * Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>

struct nft_bitmap_elem {
	struct list_head	head;
	struct nft_set_ext	ext;
};

/* This bitmap uses two bits to represent one element. These two bits determine
 * the element state in the current and the future generation.
 *
 * An element can be in three states. The generation cursor is represented using
 * the ^ character, note that this cursor shifts on every succesful transaction.
 * If no transaction is going on, we observe all elements are in the following
 * state:
 *
 * 11 = this element is active in the current generation. In case of no updates,
 * ^    it stays active in the next generation.
 * 00 = this element is inactive in the current generation. In case of no
 * ^    updates, it stays inactive in the next generation.
 *
 * On transaction handling, we observe these two temporary states:
 *
 * 01 = this element is inactive in the current generation and it becomes active
 * ^    in the next one. This happens when the element is inserted but commit
 *      path has not yet been executed yet, so activation is still pending. On
 *      transaction abortion, the element is removed.
 * 10 = this element is active in the current generation and it becomes inactive
 * ^    in the next one. This happens when the element is deactivated but commit
 *      path has not yet been executed yet, so removal is still pending. On
 *      transation abortion, the next generation bit is reset to go back to
 *      restore its previous state.
 */
struct nft_bitmap {
	struct	list_head	list;
	u16			bitmap_size;
	u8			bitmap[];
};

static inline void nft_bitmap_location(const struct nft_set *set,
				       const void *key,
				       u32 *idx, u32 *off)
{
	u32 k;

	if (set->klen == 2)
		k = *(u16 *)key;
	else
		k = *(u8 *)key;
	k <<= 1;

	*idx = k / BITS_PER_BYTE;
	*off = k % BITS_PER_BYTE;
}

/* Fetch the two bits that represent the element and check if it is active based
 * on the generation mask.
 */
static inline bool
nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
{
	return (bitmap[idx] & (0x3 << off)) & (genmask << off);
}

static bool nft_bitmap_lookup(const struct net *net, const struct nft_set *set,
			      const u32 *key, const struct nft_set_ext **ext)
{
	const struct nft_bitmap *priv = nft_set_priv(set);
	u8 genmask = nft_genmask_cur(net);
	u32 idx, off;

	nft_bitmap_location(set, key, &idx, &off);

	return nft_bitmap_active(priv->bitmap, idx, off, genmask);
}

static struct nft_bitmap_elem *
nft_bitmap_elem_find(const struct nft_set *set, struct nft_bitmap_elem *this,
		     u8 genmask)
{
	const struct nft_bitmap *priv = nft_set_priv(set);
	struct nft_bitmap_elem *be;

	list_for_each_entry_rcu(be, &priv->list, head) {
		if (memcmp(nft_set_ext_key(&be->ext),
			   nft_set_ext_key(&this->ext), set->klen) ||
		    !nft_set_elem_active(&be->ext, genmask))
			continue;

		return be;
	}
	return NULL;
}

static int nft_bitmap_insert(const struct net *net, const struct nft_set *set,
			     const struct nft_set_elem *elem,
			     struct nft_set_ext **ext)
{
	struct nft_bitmap *priv = nft_set_priv(set);
	struct nft_bitmap_elem *new = elem->priv, *be;
	u8 genmask = nft_genmask_next(net);
	u32 idx, off;

	be = nft_bitmap_elem_find(set, new, genmask);
	if (be) {
		*ext = &be->ext;
		return -EEXIST;
	}

	nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off);
	/* Enter 01 state. */
	priv->bitmap[idx] |= (genmask << off);
	list_add_tail_rcu(&new->head, &priv->list);

	return 0;
}

static void nft_bitmap_remove(const struct net *net,
			      const struct nft_set *set,
			      const struct nft_set_elem *elem)
{
	struct nft_bitmap *priv = nft_set_priv(set);
	struct nft_bitmap_elem *be = elem->priv;
	u8 genmask = nft_genmask_next(net);
	u32 idx, off;

	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
	/* Enter 00 state. */
	priv->bitmap[idx] &= ~(genmask << off);
	list_del_rcu(&be->head);
}

static void nft_bitmap_activate(const struct net *net,
				const struct nft_set *set,
				const struct nft_set_elem *elem)
{
	struct nft_bitmap *priv = nft_set_priv(set);
	struct nft_bitmap_elem *be = elem->priv;
	u8 genmask = nft_genmask_next(net);
	u32 idx, off;

	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
	/* Enter 11 state. */
	priv->bitmap[idx] |= (genmask << off);
	nft_set_elem_change_active(net, set, &be->ext);
}

static bool nft_bitmap_flush(const struct net *net,
			     const struct nft_set *set, void *_be)
{
	struct nft_bitmap *priv = nft_set_priv(set);
	u8 genmask = nft_genmask_next(net);
	struct nft_bitmap_elem *be = _be;
	u32 idx, off;

	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
	/* Enter 10 state, similar to deactivation. */
	priv->bitmap[idx] &= ~(genmask << off);
	nft_set_elem_change_active(net, set, &be->ext);

	return true;
}

static void *nft_bitmap_deactivate(const struct net *net,
				   const struct nft_set *set,
				   const struct nft_set_elem *elem)
{
	struct nft_bitmap *priv = nft_set_priv(set);
	struct nft_bitmap_elem *this = elem->priv, *be;
	u8 genmask = nft_genmask_next(net);
	u32 idx, off;

	nft_bitmap_location(set, elem->key.val.data, &idx, &off);

	be = nft_bitmap_elem_find(set, this, genmask);
	if (!be)
		return NULL;

	/* Enter 10 state. */
	priv->bitmap[idx] &= ~(genmask << off);
	nft_set_elem_change_active(net, set, &be->ext);

	return be;
}

static void nft_bitmap_walk(const struct nft_ctx *ctx,
			    struct nft_set *set,
			    struct nft_set_iter *iter)
{
	const struct nft_bitmap *priv = nft_set_priv(set);
	struct nft_bitmap_elem *be;
	struct nft_set_elem elem;

	list_for_each_entry_rcu(be, &priv->list, head) {
		if (iter->count < iter->skip)
			goto cont;
		if (!nft_set_elem_active(&be->ext, iter->genmask))
			goto cont;

		elem.priv = be;

		iter->err = iter->fn(ctx, set, iter, &elem);

		if (iter->err < 0)
			return;
cont:
		iter->count++;
	}
}

/* The bitmap size is pow(2, key length in bits) / bits per byte. This is
 * multiplied by two since each element takes two bits. For 8 bit keys, the
 * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
 */
static inline u32 nft_bitmap_size(u32 klen)
{
	return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
}

static inline u32 nft_bitmap_total_size(u32 klen)
{
	return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
}

static unsigned int nft_bitmap_privsize(const struct nlattr * const nla[],
					const struct nft_set_desc *desc)
{
	u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));

	return nft_bitmap_total_size(klen);
}

static int nft_bitmap_init(const struct nft_set *set,
			 const struct nft_set_desc *desc,
			 const struct nlattr * const nla[])
{
	struct nft_bitmap *priv = nft_set_priv(set);

	INIT_LIST_HEAD(&priv->list);
	priv->bitmap_size = nft_bitmap_size(set->klen);

	return 0;
}

static void nft_bitmap_destroy(const struct nft_set *set)
{
	struct nft_bitmap *priv = nft_set_priv(set);
	struct nft_bitmap_elem *be, *n;

	list_for_each_entry_safe(be, n, &priv->list, head)
		nft_set_elem_destroy(set, be, true);
}

static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
				struct nft_set_estimate *est)
{
	/* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
	if (desc->klen > 2)
		return false;

	est->size   = nft_bitmap_total_size(desc->klen);
	est->lookup = NFT_SET_CLASS_O_1;
	est->space  = NFT_SET_CLASS_O_1;

	return true;
}

static struct nft_set_type nft_bitmap_type;
static struct nft_set_ops nft_bitmap_ops __read_mostly = {
	.type		= &nft_bitmap_type,
	.privsize	= nft_bitmap_privsize,
	.elemsize	= offsetof(struct nft_bitmap_elem, ext),
	.estimate	= nft_bitmap_estimate,
	.init		= nft_bitmap_init,
	.destroy	= nft_bitmap_destroy,
	.insert		= nft_bitmap_insert,
	.remove		= nft_bitmap_remove,
	.deactivate	= nft_bitmap_deactivate,
	.flush		= nft_bitmap_flush,
	.activate	= nft_bitmap_activate,
	.lookup		= nft_bitmap_lookup,
	.walk		= nft_bitmap_walk,
};

static struct nft_set_type nft_bitmap_type __read_mostly = {
	.ops		= &nft_bitmap_ops,
	.owner		= THIS_MODULE,
};

static int __init nft_bitmap_module_init(void)
{
	return nft_register_set(&nft_bitmap_type);
}

static void __exit nft_bitmap_module_exit(void)
{
	nft_unregister_set(&nft_bitmap_type);
}

module_init(nft_bitmap_module_init);
module_exit(nft_bitmap_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
MODULE_ALIAS_NFT_SET();
Commit	Line	Data
665153ff PNA	1	/*
	2	* Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*/
	8
	9	#include <linux/kernel.h>
	10	#include <linux/init.h>
	11	#include <linux/module.h>
	12	#include <linux/list.h>
	13	#include <linux/netlink.h>
	14	#include <linux/netfilter.h>
	15	#include <linux/netfilter/nf_tables.h>
	16	#include <net/netfilter/nf_tables.h>
	17
e920dde5 PNA	18	struct nft_bitmap_elem {
	19	struct list_head head;
	20	struct nft_set_ext ext;
	21	};
	22
665153ff PNA	23	/* This bitmap uses two bits to represent one element. These two bits determine
	24	* the element state in the current and the future generation.
	25	*
	26	* An element can be in three states. The generation cursor is represented using
	27	* the ^ character, note that this cursor shifts on every succesful transaction.
	28	* If no transaction is going on, we observe all elements are in the following
	29	* state:
	30	*
	31	* 11 = this element is active in the current generation. In case of no updates,
	32	* ^ it stays active in the next generation.
	33	* 00 = this element is inactive in the current generation. In case of no
	34	* ^ updates, it stays inactive in the next generation.
	35	*
	36	* On transaction handling, we observe these two temporary states:
	37	*
	38	* 01 = this element is inactive in the current generation and it becomes active
	39	* ^ in the next one. This happens when the element is inserted but commit
	40	* path has not yet been executed yet, so activation is still pending. On
	41	* transaction abortion, the element is removed.
	42	* 10 = this element is active in the current generation and it becomes inactive
	43	* ^ in the next one. This happens when the element is deactivated but commit
	44	* path has not yet been executed yet, so removal is still pending. On
	45	* transation abortion, the next generation bit is reset to go back to
	46	* restore its previous state.
	47	*/
	48	struct nft_bitmap {
e920dde5 PNA	49	struct list_head list;
	50	u16 bitmap_size;
	51	u8 bitmap[];
665153ff PNA	52	};
665153ff PNA	53
fd89b23a LZ	54	static inline void nft_bitmap_location(const struct nft_set *set,
	55	const void *key,
	56	u32 idx, u32 off)
665153ff	57	{
fd89b23a LZ	58	u32 k;
	59
	60	if (set->klen == 2)
	61	k = (u16 )key;
	62	else
	63	k = (u8 )key;
	64	k <<= 1;
665153ff PNA	65
	66	*idx = k / BITS_PER_BYTE;
	67	*off = k % BITS_PER_BYTE;
	68	}
	69
	70	/* Fetch the two bits that represent the element and check if it is active based
	71	* on the generation mask.
	72	*/
	73	static inline bool
	74	nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
	75	{
	76	return (bitmap[idx] & (0x3 << off)) & (genmask << off);
	77	}
	78
	79	static bool nft_bitmap_lookup(const struct net net, const struct nft_set set,
	80	const u32 key, const struct nft_set_ext *ext)
	81	{
	82	const struct nft_bitmap *priv = nft_set_priv(set);
	83	u8 genmask = nft_genmask_cur(net);
	84	u32 idx, off;
	85
fd89b23a	86	nft_bitmap_location(set, key, &idx, &off);
665153ff PNA	87
	88	return nft_bitmap_active(priv->bitmap, idx, off, genmask);
	89	}
	90
e920dde5 PNA	91	static struct nft_bitmap_elem *
	92	nft_bitmap_elem_find(const struct nft_set set, struct nft_bitmap_elem this,
	93	u8 genmask)
	94	{
	95	const struct nft_bitmap *priv = nft_set_priv(set);
	96	struct nft_bitmap_elem *be;
	97
	98	list_for_each_entry_rcu(be, &priv->list, head) {
	99	if (memcmp(nft_set_ext_key(&be->ext),
	100	nft_set_ext_key(&this->ext), set->klen) \|\|
	101	!nft_set_elem_active(&be->ext, genmask))
	102	continue;
	103
	104	return be;
	105	}
	106	return NULL;
	107	}
	108
665153ff PNA	109	static int nft_bitmap_insert(const struct net net, const struct nft_set set,
665153ff PNA	110	const struct nft_set_elem *elem,
e920dde5	111	struct nft_set_ext **ext)
665153ff PNA	112	{
665153ff PNA	113	struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	114	struct nft_bitmap_elem new = elem->priv, be;
665153ff PNA	115	u8 genmask = nft_genmask_next(net);
	116	u32 idx, off;
	117
e920dde5 PNA	118	be = nft_bitmap_elem_find(set, new, genmask);
	119	if (be) {
	120	*ext = &be->ext;
665153ff	121	return -EEXIST;
e920dde5	122	}
665153ff	123
e920dde5	124	nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off);
665153ff PNA	125	/* Enter 01 state. */
665153ff PNA	126	priv->bitmap[idx] \|= (genmask << off);
e920dde5	127	list_add_tail_rcu(&new->head, &priv->list);
665153ff PNA	128
	129	return 0;
	130	}
	131
	132	static void nft_bitmap_remove(const struct net *net,
	133	const struct nft_set *set,
	134	const struct nft_set_elem *elem)
	135	{
	136	struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	137	struct nft_bitmap_elem *be = elem->priv;
665153ff PNA	138	u8 genmask = nft_genmask_next(net);
	139	u32 idx, off;
	140
e920dde5	141	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
665153ff PNA	142	/* Enter 00 state. */
665153ff PNA	143	priv->bitmap[idx] &= ~(genmask << off);
e920dde5	144	list_del_rcu(&be->head);
665153ff PNA	145	}
	146
	147	static void nft_bitmap_activate(const struct net *net,
	148	const struct nft_set *set,
	149	const struct nft_set_elem *elem)
	150	{
	151	struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	152	struct nft_bitmap_elem *be = elem->priv;
665153ff PNA	153	u8 genmask = nft_genmask_next(net);
	154	u32 idx, off;
	155
e920dde5	156	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
665153ff PNA	157	/* Enter 11 state. */
665153ff PNA	158	priv->bitmap[idx] \|= (genmask << off);
e920dde5	159	nft_set_elem_change_active(net, set, &be->ext);
665153ff PNA	160	}
	161
	162	static bool nft_bitmap_flush(const struct net *net,
e920dde5	163	const struct nft_set set, void _be)
665153ff PNA	164	{
	165	struct nft_bitmap *priv = nft_set_priv(set);
	166	u8 genmask = nft_genmask_next(net);
e920dde5	167	struct nft_bitmap_elem *be = _be;
665153ff PNA	168	u32 idx, off;
665153ff PNA	169
e920dde5	170	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
665153ff PNA	171	/* Enter 10 state, similar to deactivation. */
665153ff PNA	172	priv->bitmap[idx] &= ~(genmask << off);
e920dde5	173	nft_set_elem_change_active(net, set, &be->ext);
665153ff PNA	174
	175	return true;
	176	}
	177
665153ff PNA	178	static void nft_bitmap_deactivate(const struct net net,
	179	const struct nft_set *set,
	180	const struct nft_set_elem *elem)
	181	{
	182	struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	183	struct nft_bitmap_elem this = elem->priv, be;
665153ff	184	u8 genmask = nft_genmask_next(net);
fd89b23a	185	u32 idx, off;
665153ff	186
fd89b23a	187	nft_bitmap_location(set, elem->key.val.data, &idx, &off);
665153ff	188
e920dde5 PNA	189	be = nft_bitmap_elem_find(set, this, genmask);
e920dde5 PNA	190	if (!be)
665153ff PNA	191	return NULL;
	192
	193	/* Enter 10 state. */
	194	priv->bitmap[idx] &= ~(genmask << off);
e920dde5	195	nft_set_elem_change_active(net, set, &be->ext);
665153ff	196
e920dde5	197	return be;
665153ff PNA	198	}
	199
	200	static void nft_bitmap_walk(const struct nft_ctx *ctx,
	201	struct nft_set *set,
	202	struct nft_set_iter *iter)
	203	{
	204	const struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	205	struct nft_bitmap_elem *be;
665153ff	206	struct nft_set_elem elem;
e920dde5 PNA	207
	208	list_for_each_entry_rcu(be, &priv->list, head) {
	209	if (iter->count < iter->skip)
	210	goto cont;
	211	if (!nft_set_elem_active(&be->ext, iter->genmask))
	212	goto cont;
	213
	214	elem.priv = be;
	215
	216	iter->err = iter->fn(ctx, set, iter, &elem);
	217
	218	if (iter->err < 0)
	219	return;
665153ff	220	cont:
e920dde5	221	iter->count++;
665153ff PNA	222	}
	223	}
	224
	225	/* The bitmap size is pow(2, key length in bits) / bits per byte. This is
	226	* multiplied by two since each element takes two bits. For 8 bit keys, the
	227	* bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
	228	*/
	229	static inline u32 nft_bitmap_size(u32 klen)
	230	{
	231	return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
	232	}
	233
	234	static inline u32 nft_bitmap_total_size(u32 klen)
	235	{
	236	return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
	237	}
	238
347b408d PNA	239	static unsigned int nft_bitmap_privsize(const struct nlattr * const nla[],
347b408d PNA	240	const struct nft_set_desc *desc)
665153ff PNA	241	{
	242	u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
	243
	244	return nft_bitmap_total_size(klen);
	245	}
	246
	247	static int nft_bitmap_init(const struct nft_set *set,
	248	const struct nft_set_desc *desc,
	249	const struct nlattr * const nla[])
	250	{
	251	struct nft_bitmap *priv = nft_set_priv(set);
	252
e920dde5	253	INIT_LIST_HEAD(&priv->list);
13aa5a8f	254	priv->bitmap_size = nft_bitmap_size(set->klen);
665153ff PNA	255
	256	return 0;
	257	}
	258
	259	static void nft_bitmap_destroy(const struct nft_set *set)
	260	{
54a5f9d9 LZ	261	struct nft_bitmap *priv = nft_set_priv(set);
	262	struct nft_bitmap_elem be, n;
	263
	264	list_for_each_entry_safe(be, n, &priv->list, head)
	265	nft_set_elem_destroy(set, be, true);
665153ff PNA	266	}
	267
	268	static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
	269	struct nft_set_estimate *est)
	270	{
	271	/* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
	272	if (desc->klen > 2)
	273	return false;
	274
	275	est->size = nft_bitmap_total_size(desc->klen);
	276	est->lookup = NFT_SET_CLASS_O_1;
	277	est->space = NFT_SET_CLASS_O_1;
	278
	279	return true;
	280	}
	281
2b664957	282	static struct nft_set_type nft_bitmap_type;
665153ff	283	static struct nft_set_ops nft_bitmap_ops __read_mostly = {
2b664957	284	.type = &nft_bitmap_type,
665153ff	285	.privsize = nft_bitmap_privsize,
e920dde5	286	.elemsize = offsetof(struct nft_bitmap_elem, ext),
665153ff PNA	287	.estimate = nft_bitmap_estimate,
	288	.init = nft_bitmap_init,
	289	.destroy = nft_bitmap_destroy,
	290	.insert = nft_bitmap_insert,
	291	.remove = nft_bitmap_remove,
	292	.deactivate = nft_bitmap_deactivate,
	293	.flush = nft_bitmap_flush,
	294	.activate = nft_bitmap_activate,
	295	.lookup = nft_bitmap_lookup,
	296	.walk = nft_bitmap_walk,
2b664957 PNA	297	};
	298
	299	static struct nft_set_type nft_bitmap_type __read_mostly = {
	300	.ops = &nft_bitmap_ops,
665153ff PNA	301	.owner = THIS_MODULE,
	302	};
	303
	304	static int __init nft_bitmap_module_init(void)
	305	{
2b664957	306	return nft_register_set(&nft_bitmap_type);
665153ff PNA	307	}
	308
	309	static void __exit nft_bitmap_module_exit(void)
	310	{
2b664957	311	nft_unregister_set(&nft_bitmap_type);
665153ff PNA	312	}
	313
	314	module_init(nft_bitmap_module_init);
	315	module_exit(nft_bitmap_module_exit);
	316
	317	MODULE_LICENSE("GPL");
	318	MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
	319	MODULE_ALIAS_NFT_SET();