2 * Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
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.
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>
18 struct nft_bitmap_elem
{
19 struct list_head head
;
20 struct nft_set_ext ext
;
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.
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
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.
36 * On transaction handling, we observe these two temporary states:
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.
49 struct list_head list
;
54 static inline void nft_bitmap_location(const struct nft_set
*set
,
66 *idx
= k
/ BITS_PER_BYTE
;
67 *off
= k
% BITS_PER_BYTE
;
70 /* Fetch the two bits that represent the element and check if it is active based
71 * on the generation mask.
74 nft_bitmap_active(const u8
*bitmap
, u32 idx
, u32 off
, u8 genmask
)
76 return (bitmap
[idx
] & (0x3 << off
)) & (genmask
<< off
);
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
)
82 const struct nft_bitmap
*priv
= nft_set_priv(set
);
83 u8 genmask
= nft_genmask_cur(net
);
86 nft_bitmap_location(set
, key
, &idx
, &off
);
88 return nft_bitmap_active(priv
->bitmap
, idx
, off
, genmask
);
91 static struct nft_bitmap_elem
*
92 nft_bitmap_elem_find(const struct nft_set
*set
, struct nft_bitmap_elem
*this,
95 const struct nft_bitmap
*priv
= nft_set_priv(set
);
96 struct nft_bitmap_elem
*be
;
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
))
109 static int nft_bitmap_insert(const struct net
*net
, const struct nft_set
*set
,
110 const struct nft_set_elem
*elem
,
111 struct nft_set_ext
**ext
)
113 struct nft_bitmap
*priv
= nft_set_priv(set
);
114 struct nft_bitmap_elem
*new = elem
->priv
, *be
;
115 u8 genmask
= nft_genmask_next(net
);
118 be
= nft_bitmap_elem_find(set
, new, genmask
);
124 nft_bitmap_location(set
, nft_set_ext_key(&new->ext
), &idx
, &off
);
125 /* Enter 01 state. */
126 priv
->bitmap
[idx
] |= (genmask
<< off
);
127 list_add_tail_rcu(&new->head
, &priv
->list
);
132 static void nft_bitmap_remove(const struct net
*net
,
133 const struct nft_set
*set
,
134 const struct nft_set_elem
*elem
)
136 struct nft_bitmap
*priv
= nft_set_priv(set
);
137 struct nft_bitmap_elem
*be
= elem
->priv
;
138 u8 genmask
= nft_genmask_next(net
);
141 nft_bitmap_location(set
, nft_set_ext_key(&be
->ext
), &idx
, &off
);
142 /* Enter 00 state. */
143 priv
->bitmap
[idx
] &= ~(genmask
<< off
);
144 list_del_rcu(&be
->head
);
147 static void nft_bitmap_activate(const struct net
*net
,
148 const struct nft_set
*set
,
149 const struct nft_set_elem
*elem
)
151 struct nft_bitmap
*priv
= nft_set_priv(set
);
152 struct nft_bitmap_elem
*be
= elem
->priv
;
153 u8 genmask
= nft_genmask_next(net
);
156 nft_bitmap_location(set
, nft_set_ext_key(&be
->ext
), &idx
, &off
);
157 /* Enter 11 state. */
158 priv
->bitmap
[idx
] |= (genmask
<< off
);
159 nft_set_elem_change_active(net
, set
, &be
->ext
);
162 static bool nft_bitmap_flush(const struct net
*net
,
163 const struct nft_set
*set
, void *_be
)
165 struct nft_bitmap
*priv
= nft_set_priv(set
);
166 u8 genmask
= nft_genmask_next(net
);
167 struct nft_bitmap_elem
*be
= _be
;
170 nft_bitmap_location(set
, nft_set_ext_key(&be
->ext
), &idx
, &off
);
171 /* Enter 10 state, similar to deactivation. */
172 priv
->bitmap
[idx
] &= ~(genmask
<< off
);
173 nft_set_elem_change_active(net
, set
, &be
->ext
);
178 static void *nft_bitmap_deactivate(const struct net
*net
,
179 const struct nft_set
*set
,
180 const struct nft_set_elem
*elem
)
182 struct nft_bitmap
*priv
= nft_set_priv(set
);
183 struct nft_bitmap_elem
*this = elem
->priv
, *be
;
184 u8 genmask
= nft_genmask_next(net
);
187 nft_bitmap_location(set
, elem
->key
.val
.data
, &idx
, &off
);
189 be
= nft_bitmap_elem_find(set
, this, genmask
);
193 /* Enter 10 state. */
194 priv
->bitmap
[idx
] &= ~(genmask
<< off
);
195 nft_set_elem_change_active(net
, set
, &be
->ext
);
200 static void nft_bitmap_walk(const struct nft_ctx
*ctx
,
202 struct nft_set_iter
*iter
)
204 const struct nft_bitmap
*priv
= nft_set_priv(set
);
205 struct nft_bitmap_elem
*be
;
206 struct nft_set_elem elem
;
208 list_for_each_entry_rcu(be
, &priv
->list
, head
) {
209 if (iter
->count
< iter
->skip
)
211 if (!nft_set_elem_active(&be
->ext
, iter
->genmask
))
216 iter
->err
= iter
->fn(ctx
, set
, iter
, &elem
);
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.
229 static inline u32
nft_bitmap_size(u32 klen
)
231 return ((2 << ((klen
* BITS_PER_BYTE
) - 1)) / BITS_PER_BYTE
) << 1;
234 static inline u32
nft_bitmap_total_size(u32 klen
)
236 return sizeof(struct nft_bitmap
) + nft_bitmap_size(klen
);
239 static unsigned int nft_bitmap_privsize(const struct nlattr
* const nla
[])
241 u32 klen
= ntohl(nla_get_be32(nla
[NFTA_SET_KEY_LEN
]));
243 return nft_bitmap_total_size(klen
);
246 static int nft_bitmap_init(const struct nft_set
*set
,
247 const struct nft_set_desc
*desc
,
248 const struct nlattr
* const nla
[])
250 struct nft_bitmap
*priv
= nft_set_priv(set
);
252 INIT_LIST_HEAD(&priv
->list
);
253 priv
->bitmap_size
= nft_bitmap_size(set
->klen
);
258 static void nft_bitmap_destroy(const struct nft_set
*set
)
262 static bool nft_bitmap_estimate(const struct nft_set_desc
*desc
, u32 features
,
263 struct nft_set_estimate
*est
)
265 /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
269 est
->size
= nft_bitmap_total_size(desc
->klen
);
270 est
->lookup
= NFT_SET_CLASS_O_1
;
271 est
->space
= NFT_SET_CLASS_O_1
;
276 static struct nft_set_ops nft_bitmap_ops __read_mostly
= {
277 .privsize
= nft_bitmap_privsize
,
278 .elemsize
= offsetof(struct nft_bitmap_elem
, ext
),
279 .estimate
= nft_bitmap_estimate
,
280 .init
= nft_bitmap_init
,
281 .destroy
= nft_bitmap_destroy
,
282 .insert
= nft_bitmap_insert
,
283 .remove
= nft_bitmap_remove
,
284 .deactivate
= nft_bitmap_deactivate
,
285 .flush
= nft_bitmap_flush
,
286 .activate
= nft_bitmap_activate
,
287 .lookup
= nft_bitmap_lookup
,
288 .walk
= nft_bitmap_walk
,
289 .owner
= THIS_MODULE
,
292 static int __init
nft_bitmap_module_init(void)
294 return nft_register_set(&nft_bitmap_ops
);
297 static void __exit
nft_bitmap_module_exit(void)
299 nft_unregister_set(&nft_bitmap_ops
);
302 module_init(nft_bitmap_module_init
);
303 module_exit(nft_bitmap_module_exit
);
305 MODULE_LICENSE("GPL");
306 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
307 MODULE_ALIAS_NFT_SET();