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 void *nft_bitmap_get(const struct net *net, const struct nft_set *set,
110 const struct nft_set_elem *elem, unsigned int flags)
112 const struct nft_bitmap *priv = nft_set_priv(set);
113 u8 genmask = nft_genmask_cur(net);
114 struct nft_bitmap_elem *be;
116 list_for_each_entry_rcu(be, &priv->list, head) {
117 if (memcmp(nft_set_ext_key(&be->ext), elem->key.val.data, set->klen) ||
118 !nft_set_elem_active(&be->ext, genmask))
123 return ERR_PTR(-ENOENT);
126 static int nft_bitmap_insert(const struct net *net, const struct nft_set *set,
127 const struct nft_set_elem *elem,
128 struct nft_set_ext **ext)
130 struct nft_bitmap *priv = nft_set_priv(set);
131 struct nft_bitmap_elem *new = elem->priv, *be;
132 u8 genmask = nft_genmask_next(net);
135 be = nft_bitmap_elem_find(set, new, genmask);
141 nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off);
142 /* Enter 01 state. */
143 priv->bitmap[idx] |= (genmask << off);
144 list_add_tail_rcu(&new->head, &priv->list);
149 static void nft_bitmap_remove(const struct net *net,
150 const struct nft_set *set,
151 const struct nft_set_elem *elem)
153 struct nft_bitmap *priv = nft_set_priv(set);
154 struct nft_bitmap_elem *be = elem->priv;
155 u8 genmask = nft_genmask_next(net);
158 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
159 /* Enter 00 state. */
160 priv->bitmap[idx] &= ~(genmask << off);
161 list_del_rcu(&be->head);
164 static void nft_bitmap_activate(const struct net *net,
165 const struct nft_set *set,
166 const struct nft_set_elem *elem)
168 struct nft_bitmap *priv = nft_set_priv(set);
169 struct nft_bitmap_elem *be = elem->priv;
170 u8 genmask = nft_genmask_next(net);
173 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
174 /* Enter 11 state. */
175 priv->bitmap[idx] |= (genmask << off);
176 nft_set_elem_change_active(net, set, &be->ext);
179 static bool nft_bitmap_flush(const struct net *net,
180 const struct nft_set *set, void *_be)
182 struct nft_bitmap *priv = nft_set_priv(set);
183 u8 genmask = nft_genmask_next(net);
184 struct nft_bitmap_elem *be = _be;
187 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
188 /* Enter 10 state, similar to deactivation. */
189 priv->bitmap[idx] &= ~(genmask << off);
190 nft_set_elem_change_active(net, set, &be->ext);
195 static void *nft_bitmap_deactivate(const struct net *net,
196 const struct nft_set *set,
197 const struct nft_set_elem *elem)
199 struct nft_bitmap *priv = nft_set_priv(set);
200 struct nft_bitmap_elem *this = elem->priv, *be;
201 u8 genmask = nft_genmask_next(net);
204 nft_bitmap_location(set, elem->key.val.data, &idx, &off);
206 be = nft_bitmap_elem_find(set, this, genmask);
210 /* Enter 10 state. */
211 priv->bitmap[idx] &= ~(genmask << off);
212 nft_set_elem_change_active(net, set, &be->ext);
217 static void nft_bitmap_walk(const struct nft_ctx *ctx,
219 struct nft_set_iter *iter)
221 const struct nft_bitmap *priv = nft_set_priv(set);
222 struct nft_bitmap_elem *be;
223 struct nft_set_elem elem;
225 list_for_each_entry_rcu(be, &priv->list, head) {
226 if (iter->count < iter->skip)
228 if (!nft_set_elem_active(&be->ext, iter->genmask))
233 iter->err = iter->fn(ctx, set, iter, &elem);
242 /* The bitmap size is pow(2, key length in bits) / bits per byte. This is
243 * multiplied by two since each element takes two bits. For 8 bit keys, the
244 * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
246 static inline u32 nft_bitmap_size(u32 klen)
248 return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
251 static inline u32 nft_bitmap_total_size(u32 klen)
253 return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
256 static unsigned int nft_bitmap_privsize(const struct nlattr * const nla[],
257 const struct nft_set_desc *desc)
259 u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
261 return nft_bitmap_total_size(klen);
264 static int nft_bitmap_init(const struct nft_set *set,
265 const struct nft_set_desc *desc,
266 const struct nlattr * const nla[])
268 struct nft_bitmap *priv = nft_set_priv(set);
270 INIT_LIST_HEAD(&priv->list);
271 priv->bitmap_size = nft_bitmap_size(set->klen);
276 static void nft_bitmap_destroy(const struct nft_set *set)
278 struct nft_bitmap *priv = nft_set_priv(set);
279 struct nft_bitmap_elem *be, *n;
281 list_for_each_entry_safe(be, n, &priv->list, head)
282 nft_set_elem_destroy(set, be, true);
285 static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
286 struct nft_set_estimate *est)
288 /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
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;
299 static struct nft_set_type nft_bitmap_type;
300 static struct nft_set_ops nft_bitmap_ops __read_mostly = {
301 .type = &nft_bitmap_type,
302 .privsize = nft_bitmap_privsize,
303 .elemsize = offsetof(struct nft_bitmap_elem, ext),
304 .estimate = nft_bitmap_estimate,
305 .init = nft_bitmap_init,
306 .destroy = nft_bitmap_destroy,
307 .insert = nft_bitmap_insert,
308 .remove = nft_bitmap_remove,
309 .deactivate = nft_bitmap_deactivate,
310 .flush = nft_bitmap_flush,
311 .activate = nft_bitmap_activate,
312 .lookup = nft_bitmap_lookup,
313 .walk = nft_bitmap_walk,
314 .get = nft_bitmap_get,
317 static struct nft_set_type nft_bitmap_type __read_mostly = {
318 .ops = &nft_bitmap_ops,
319 .owner = THIS_MODULE,
322 static int __init nft_bitmap_module_init(void)
324 return nft_register_set(&nft_bitmap_type);
327 static void __exit nft_bitmap_module_exit(void)
329 nft_unregister_set(&nft_bitmap_type);
332 module_init(nft_bitmap_module_init);
333 module_exit(nft_bitmap_module_exit);
335 MODULE_LICENSE("GPL");
336 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
337 MODULE_ALIAS_NFT_SET();