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();