1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
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>
13 #include <net/netfilter/nf_tables_core.h>
15 struct nft_bitmap_elem {
16 struct list_head head;
17 struct nft_set_ext ext;
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.
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
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.
33 * On transaction handling, we observe these two temporary states:
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.
46 struct list_head list;
51 static inline void nft_bitmap_location(const struct nft_set *set,
63 *idx = k / BITS_PER_BYTE;
64 *off = k % BITS_PER_BYTE;
67 /* Fetch the two bits that represent the element and check if it is active based
68 * on the generation mask.
71 nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
73 return (bitmap[idx] & (0x3 << off)) & (genmask << off);
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)
79 const struct nft_bitmap *priv = nft_set_priv(set);
80 u8 genmask = nft_genmask_cur(net);
83 nft_bitmap_location(set, key, &idx, &off);
85 return nft_bitmap_active(priv->bitmap, idx, off, genmask);
88 static struct nft_bitmap_elem *
89 nft_bitmap_elem_find(const struct nft_set *set, struct nft_bitmap_elem *this,
92 const struct nft_bitmap *priv = nft_set_priv(set);
93 struct nft_bitmap_elem *be;
95 list_for_each_entry_rcu(be, &priv->list, head) {
96 if (memcmp(nft_set_ext_key(&be->ext),
97 nft_set_ext_key(&this->ext), set->klen) ||
98 !nft_set_elem_active(&be->ext, genmask))
106 static void *nft_bitmap_get(const struct net *net, const struct nft_set *set,
107 const struct nft_set_elem *elem, unsigned int flags)
109 const struct nft_bitmap *priv = nft_set_priv(set);
110 u8 genmask = nft_genmask_cur(net);
111 struct nft_bitmap_elem *be;
113 list_for_each_entry_rcu(be, &priv->list, head) {
114 if (memcmp(nft_set_ext_key(&be->ext), elem->key.val.data, set->klen) ||
115 !nft_set_elem_active(&be->ext, genmask))
120 return ERR_PTR(-ENOENT);
123 static int nft_bitmap_insert(const struct net *net, const struct nft_set *set,
124 const struct nft_set_elem *elem,
125 struct nft_set_ext **ext)
127 struct nft_bitmap *priv = nft_set_priv(set);
128 struct nft_bitmap_elem *new = elem->priv, *be;
129 u8 genmask = nft_genmask_next(net);
132 be = nft_bitmap_elem_find(set, new, genmask);
138 nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off);
139 /* Enter 01 state. */
140 priv->bitmap[idx] |= (genmask << off);
141 list_add_tail_rcu(&new->head, &priv->list);
146 static void nft_bitmap_remove(const struct net *net,
147 const struct nft_set *set,
148 const struct nft_set_elem *elem)
150 struct nft_bitmap *priv = nft_set_priv(set);
151 struct nft_bitmap_elem *be = elem->priv;
152 u8 genmask = nft_genmask_next(net);
155 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
156 /* Enter 00 state. */
157 priv->bitmap[idx] &= ~(genmask << off);
158 list_del_rcu(&be->head);
161 static void nft_bitmap_activate(const struct net *net,
162 const struct nft_set *set,
163 const struct nft_set_elem *elem)
165 struct nft_bitmap *priv = nft_set_priv(set);
166 struct nft_bitmap_elem *be = elem->priv;
167 u8 genmask = nft_genmask_next(net);
170 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
171 /* Enter 11 state. */
172 priv->bitmap[idx] |= (genmask << off);
173 nft_set_elem_change_active(net, set, &be->ext);
176 static bool nft_bitmap_flush(const struct net *net,
177 const struct nft_set *set, void *_be)
179 struct nft_bitmap *priv = nft_set_priv(set);
180 u8 genmask = nft_genmask_next(net);
181 struct nft_bitmap_elem *be = _be;
184 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
185 /* Enter 10 state, similar to deactivation. */
186 priv->bitmap[idx] &= ~(genmask << off);
187 nft_set_elem_change_active(net, set, &be->ext);
192 static void *nft_bitmap_deactivate(const struct net *net,
193 const struct nft_set *set,
194 const struct nft_set_elem *elem)
196 struct nft_bitmap *priv = nft_set_priv(set);
197 struct nft_bitmap_elem *this = elem->priv, *be;
198 u8 genmask = nft_genmask_next(net);
201 nft_bitmap_location(set, elem->key.val.data, &idx, &off);
203 be = nft_bitmap_elem_find(set, this, genmask);
207 /* Enter 10 state. */
208 priv->bitmap[idx] &= ~(genmask << off);
209 nft_set_elem_change_active(net, set, &be->ext);
214 static void nft_bitmap_walk(const struct nft_ctx *ctx,
216 struct nft_set_iter *iter)
218 const struct nft_bitmap *priv = nft_set_priv(set);
219 struct nft_bitmap_elem *be;
220 struct nft_set_elem elem;
222 list_for_each_entry_rcu(be, &priv->list, head) {
223 if (iter->count < iter->skip)
225 if (!nft_set_elem_active(&be->ext, iter->genmask))
230 iter->err = iter->fn(ctx, set, iter, &elem);
239 /* The bitmap size is pow(2, key length in bits) / bits per byte. This is
240 * multiplied by two since each element takes two bits. For 8 bit keys, the
241 * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
243 static inline u32 nft_bitmap_size(u32 klen)
245 return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
248 static inline u64 nft_bitmap_total_size(u32 klen)
250 return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
253 static u64 nft_bitmap_privsize(const struct nlattr * const nla[],
254 const struct nft_set_desc *desc)
256 u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
258 return nft_bitmap_total_size(klen);
261 static int nft_bitmap_init(const struct nft_set *set,
262 const struct nft_set_desc *desc,
263 const struct nlattr * const nla[])
265 struct nft_bitmap *priv = nft_set_priv(set);
267 INIT_LIST_HEAD(&priv->list);
268 priv->bitmap_size = nft_bitmap_size(set->klen);
273 static void nft_bitmap_destroy(const struct nft_set *set)
275 struct nft_bitmap *priv = nft_set_priv(set);
276 struct nft_bitmap_elem *be, *n;
278 list_for_each_entry_safe(be, n, &priv->list, head)
279 nft_set_elem_destroy(set, be, true);
282 static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
283 struct nft_set_estimate *est)
285 /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
291 est->size = nft_bitmap_total_size(desc->klen);
292 est->lookup = NFT_SET_CLASS_O_1;
293 est->space = NFT_SET_CLASS_O_1;
298 const struct nft_set_type nft_set_bitmap_type = {
300 .privsize = nft_bitmap_privsize,
301 .elemsize = offsetof(struct nft_bitmap_elem, ext),
302 .estimate = nft_bitmap_estimate,
303 .init = nft_bitmap_init,
304 .destroy = nft_bitmap_destroy,
305 .insert = nft_bitmap_insert,
306 .remove = nft_bitmap_remove,
307 .deactivate = nft_bitmap_deactivate,
308 .flush = nft_bitmap_flush,
309 .activate = nft_bitmap_activate,
310 .lookup = nft_bitmap_lookup,
311 .walk = nft_bitmap_walk,
312 .get = nft_bitmap_get,