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

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
 */

#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_core.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);
	*ext = NULL;

	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 void *nft_bitmap_get(const struct net *net, const struct nft_set *set,
			    const struct nft_set_elem *elem, unsigned int flags)
{
	const struct nft_bitmap *priv = nft_set_priv(set);
	u8 genmask = nft_genmask_cur(net);
	struct nft_bitmap_elem *be;

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

		return be;
	}
	return ERR_PTR(-ENOENT);
}

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 u64 nft_bitmap_total_size(u32 klen)
{
	return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
}

static u64 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;
	else if (desc->expr)
		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;
}

const struct nft_set_type nft_set_bitmap_type = {
	.ops		= {
		.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,
		.get		= nft_bitmap_get,
	},
};
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
665153ff PNA	2	/*
665153ff PNA	3	* Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
665153ff PNA	4	*/
	5
	6	#include <linux/kernel.h>
	7	#include <linux/init.h>
	8	#include <linux/module.h>
	9	#include <linux/list.h>
	10	#include <linux/netlink.h>
	11	#include <linux/netfilter.h>
	12	#include <linux/netfilter/nf_tables.h>
5785cf15	13	#include <net/netfilter/nf_tables_core.h>
665153ff	14
e920dde5 PNA	15	struct nft_bitmap_elem {
	16	struct list_head head;
	17	struct nft_set_ext ext;
	18	};
	19
665153ff PNA	20	/* This bitmap uses two bits to represent one element. These two bits determine
	21	* the element state in the current and the future generation.
	22	*
	23	* An element can be in three states. The generation cursor is represented using
	24	* the ^ character, note that this cursor shifts on every succesful transaction.
	25	* If no transaction is going on, we observe all elements are in the following
	26	* state:
	27	*
	28	* 11 = this element is active in the current generation. In case of no updates,
	29	* ^ it stays active in the next generation.
	30	* 00 = this element is inactive in the current generation. In case of no
	31	* ^ updates, it stays inactive in the next generation.
	32	*
	33	* On transaction handling, we observe these two temporary states:
	34	*
	35	* 01 = this element is inactive in the current generation and it becomes active
	36	* ^ in the next one. This happens when the element is inserted but commit
	37	* path has not yet been executed yet, so activation is still pending. On
	38	* transaction abortion, the element is removed.
	39	* 10 = this element is active in the current generation and it becomes inactive
	40	* ^ in the next one. This happens when the element is deactivated but commit
	41	* path has not yet been executed yet, so removal is still pending. On
	42	* transation abortion, the next generation bit is reset to go back to
	43	* restore its previous state.
	44	*/
	45	struct nft_bitmap {
e920dde5 PNA	46	struct list_head list;
	47	u16 bitmap_size;
	48	u8 bitmap[];
665153ff PNA	49	};
665153ff PNA	50
fd89b23a LZ	51	static inline void nft_bitmap_location(const struct nft_set *set,
	52	const void *key,
	53	u32 idx, u32 off)
665153ff	54	{
fd89b23a LZ	55	u32 k;
	56
	57	if (set->klen == 2)
	58	k = (u16 )key;
	59	else
	60	k = (u8 )key;
	61	k <<= 1;
665153ff PNA	62
	63	*idx = k / BITS_PER_BYTE;
	64	*off = k % BITS_PER_BYTE;
	65	}
	66
	67	/* Fetch the two bits that represent the element and check if it is active based
	68	* on the generation mask.
	69	*/
	70	static inline bool
	71	nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
	72	{
	73	return (bitmap[idx] & (0x3 << off)) & (genmask << off);
	74	}
	75
	76	static bool nft_bitmap_lookup(const struct net net, const struct nft_set set,
	77	const u32 key, const struct nft_set_ext *ext)
	78	{
	79	const struct nft_bitmap *priv = nft_set_priv(set);
	80	u8 genmask = nft_genmask_cur(net);
	81	u32 idx, off;
	82
fd89b23a	83	nft_bitmap_location(set, key, &idx, &off);
24791b9a	84	*ext = NULL;
665153ff PNA	85
	86	return nft_bitmap_active(priv->bitmap, idx, off, genmask);
	87	}
	88
e920dde5 PNA	89	static struct nft_bitmap_elem *
	90	nft_bitmap_elem_find(const struct nft_set set, struct nft_bitmap_elem this,
	91	u8 genmask)
	92	{
	93	const struct nft_bitmap *priv = nft_set_priv(set);
	94	struct nft_bitmap_elem *be;
	95
	96	list_for_each_entry_rcu(be, &priv->list, head) {
	97	if (memcmp(nft_set_ext_key(&be->ext),
	98	nft_set_ext_key(&this->ext), set->klen) \|\|
	99	!nft_set_elem_active(&be->ext, genmask))
	100	continue;
	101
	102	return be;
	103	}
	104	return NULL;
	105	}
	106
ba0e4d99 PNA	107	static void nft_bitmap_get(const struct net net, const struct nft_set *set,
	108	const struct nft_set_elem *elem, unsigned int flags)
	109	{
	110	const struct nft_bitmap *priv = nft_set_priv(set);
	111	u8 genmask = nft_genmask_cur(net);
	112	struct nft_bitmap_elem *be;
	113
	114	list_for_each_entry_rcu(be, &priv->list, head) {
	115	if (memcmp(nft_set_ext_key(&be->ext), elem->key.val.data, set->klen) \|\|
	116	!nft_set_elem_active(&be->ext, genmask))
	117	continue;
	118
	119	return be;
	120	}
	121	return ERR_PTR(-ENOENT);
	122	}
	123
665153ff PNA	124	static int nft_bitmap_insert(const struct net net, const struct nft_set set,
665153ff PNA	125	const struct nft_set_elem *elem,
e920dde5	126	struct nft_set_ext **ext)
665153ff PNA	127	{
665153ff PNA	128	struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	129	struct nft_bitmap_elem new = elem->priv, be;
665153ff PNA	130	u8 genmask = nft_genmask_next(net);
	131	u32 idx, off;
	132
e920dde5 PNA	133	be = nft_bitmap_elem_find(set, new, genmask);
	134	if (be) {
	135	*ext = &be->ext;
665153ff	136	return -EEXIST;
e920dde5	137	}
665153ff	138
e920dde5	139	nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off);
665153ff PNA	140	/* Enter 01 state. */
665153ff PNA	141	priv->bitmap[idx] \|= (genmask << off);
e920dde5	142	list_add_tail_rcu(&new->head, &priv->list);
665153ff PNA	143
	144	return 0;
	145	}
	146
	147	static void nft_bitmap_remove(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 00 state. */
665153ff PNA	158	priv->bitmap[idx] &= ~(genmask << off);
e920dde5	159	list_del_rcu(&be->head);
665153ff PNA	160	}
	161
	162	static void nft_bitmap_activate(const struct net *net,
	163	const struct nft_set *set,
	164	const struct nft_set_elem *elem)
	165	{
	166	struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	167	struct nft_bitmap_elem *be = elem->priv;
665153ff PNA	168	u8 genmask = nft_genmask_next(net);
	169	u32 idx, off;
	170
e920dde5	171	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
665153ff PNA	172	/* Enter 11 state. */
665153ff PNA	173	priv->bitmap[idx] \|= (genmask << off);
e920dde5	174	nft_set_elem_change_active(net, set, &be->ext);
665153ff PNA	175	}
	176
	177	static bool nft_bitmap_flush(const struct net *net,
e920dde5	178	const struct nft_set set, void _be)
665153ff PNA	179	{
	180	struct nft_bitmap *priv = nft_set_priv(set);
	181	u8 genmask = nft_genmask_next(net);
e920dde5	182	struct nft_bitmap_elem *be = _be;
665153ff PNA	183	u32 idx, off;
665153ff PNA	184
e920dde5	185	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
665153ff PNA	186	/* Enter 10 state, similar to deactivation. */
665153ff PNA	187	priv->bitmap[idx] &= ~(genmask << off);
e920dde5	188	nft_set_elem_change_active(net, set, &be->ext);
665153ff PNA	189
	190	return true;
	191	}
	192
665153ff PNA	193	static void nft_bitmap_deactivate(const struct net net,
	194	const struct nft_set *set,
	195	const struct nft_set_elem *elem)
	196	{
	197	struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	198	struct nft_bitmap_elem this = elem->priv, be;
665153ff	199	u8 genmask = nft_genmask_next(net);
fd89b23a	200	u32 idx, off;
665153ff	201
fd89b23a	202	nft_bitmap_location(set, elem->key.val.data, &idx, &off);
665153ff	203
e920dde5 PNA	204	be = nft_bitmap_elem_find(set, this, genmask);
e920dde5 PNA	205	if (!be)
665153ff PNA	206	return NULL;
	207
	208	/* Enter 10 state. */
	209	priv->bitmap[idx] &= ~(genmask << off);
e920dde5	210	nft_set_elem_change_active(net, set, &be->ext);
665153ff	211
e920dde5	212	return be;
665153ff PNA	213	}
	214
	215	static void nft_bitmap_walk(const struct nft_ctx *ctx,
	216	struct nft_set *set,
	217	struct nft_set_iter *iter)
	218	{
	219	const struct nft_bitmap *priv = nft_set_priv(set);
e920dde5	220	struct nft_bitmap_elem *be;
665153ff	221	struct nft_set_elem elem;
e920dde5 PNA	222
	223	list_for_each_entry_rcu(be, &priv->list, head) {
	224	if (iter->count < iter->skip)
	225	goto cont;
	226	if (!nft_set_elem_active(&be->ext, iter->genmask))
	227	goto cont;
	228
	229	elem.priv = be;
	230
	231	iter->err = iter->fn(ctx, set, iter, &elem);
	232
	233	if (iter->err < 0)
	234	return;
665153ff	235	cont:
e920dde5	236	iter->count++;
665153ff PNA	237	}
	238	}
	239
	240	/* The bitmap size is pow(2, key length in bits) / bits per byte. This is
	241	* multiplied by two since each element takes two bits. For 8 bit keys, the
	242	* bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
	243	*/
	244	static inline u32 nft_bitmap_size(u32 klen)
	245	{
	246	return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
	247	}
	248
4ef360dd	249	static inline u64 nft_bitmap_total_size(u32 klen)
665153ff PNA	250	{
	251	return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
	252	}
	253
4ef360dd TY	254	static u64 nft_bitmap_privsize(const struct nlattr * const nla[],
4ef360dd TY	255	const struct nft_set_desc *desc)
665153ff PNA	256	{
	257	u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
	258
	259	return nft_bitmap_total_size(klen);
	260	}
	261
	262	static int nft_bitmap_init(const struct nft_set *set,
fbf19ddf JS	263	const struct nft_set_desc *desc,
fbf19ddf JS	264	const struct nlattr * const nla[])
665153ff PNA	265	{
	266	struct nft_bitmap *priv = nft_set_priv(set);
	267
e920dde5	268	INIT_LIST_HEAD(&priv->list);
13aa5a8f	269	priv->bitmap_size = nft_bitmap_size(set->klen);
665153ff PNA	270
	271	return 0;
	272	}
	273
	274	static void nft_bitmap_destroy(const struct nft_set *set)
	275	{
54a5f9d9 LZ	276	struct nft_bitmap *priv = nft_set_priv(set);
	277	struct nft_bitmap_elem be, n;
	278
	279	list_for_each_entry_safe(be, n, &priv->list, head)
	280	nft_set_elem_destroy(set, be, true);
665153ff PNA	281	}
	282
	283	static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
	284	struct nft_set_estimate *est)
	285	{
	286	/* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
	287	if (desc->klen > 2)
	288	return false;
d56aab26 PNA	289	else if (desc->expr)
d56aab26 PNA	290	return false;
665153ff PNA	291
	292	est->size = nft_bitmap_total_size(desc->klen);
	293	est->lookup = NFT_SET_CLASS_O_1;
	294	est->space = NFT_SET_CLASS_O_1;
	295
	296	return true;
	297	}
	298
24d19826	299	const struct nft_set_type nft_set_bitmap_type = {
71cc0873 PS	300	.ops = {
	301	.privsize = nft_bitmap_privsize,
	302	.elemsize = offsetof(struct nft_bitmap_elem, ext),
	303	.estimate = nft_bitmap_estimate,
	304	.init = nft_bitmap_init,
	305	.destroy = nft_bitmap_destroy,
	306	.insert = nft_bitmap_insert,
	307	.remove = nft_bitmap_remove,
	308	.deactivate = nft_bitmap_deactivate,
	309	.flush = nft_bitmap_flush,
	310	.activate = nft_bitmap_activate,
	311	.lookup = nft_bitmap_lookup,
	312	.walk = nft_bitmap_walk,
	313	.get = nft_bitmap_get,
	314	},
665153ff	315	};