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 nft_elem_priv priv;
17 struct list_head head;
18 struct nft_set_ext ext;
21 /* This bitmap uses two bits to represent one element. These two bits determine
22 * the element state in the current and the future generation.
24 * An element can be in three states. The generation cursor is represented using
25 * the ^ character, note that this cursor shifts on every successful transaction.
26 * If no transaction is going on, we observe all elements are in the following
29 * 11 = this element is active in the current generation. In case of no updates,
30 * ^ it stays active in the next generation.
31 * 00 = this element is inactive in the current generation. In case of no
32 * ^ updates, it stays inactive in the next generation.
34 * On transaction handling, we observe these two temporary states:
36 * 01 = this element is inactive in the current generation and it becomes active
37 * ^ in the next one. This happens when the element is inserted but commit
38 * path has not yet been executed yet, so activation is still pending. On
39 * transaction abortion, the element is removed.
40 * 10 = this element is active in the current generation and it becomes inactive
41 * ^ in the next one. This happens when the element is deactivated but commit
42 * path has not yet been executed yet, so removal is still pending. On
43 * transaction abortion, the next generation bit is reset to go back to
44 * restore its previous state.
47 struct list_head list;
52 static inline void nft_bitmap_location(const struct nft_set *set,
64 *idx = k / BITS_PER_BYTE;
65 *off = k % BITS_PER_BYTE;
68 /* Fetch the two bits that represent the element and check if it is active based
69 * on the generation mask.
72 nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
74 return (bitmap[idx] & (0x3 << off)) & (genmask << off);
77 INDIRECT_CALLABLE_SCOPE
78 bool nft_bitmap_lookup(const struct net *net, const struct nft_set *set,
79 const u32 *key, const struct nft_set_ext **ext)
81 const struct nft_bitmap *priv = nft_set_priv(set);
82 u8 genmask = nft_genmask_cur(net);
85 nft_bitmap_location(set, key, &idx, &off);
87 return nft_bitmap_active(priv->bitmap, idx, off, genmask);
90 static struct nft_bitmap_elem *
91 nft_bitmap_elem_find(const struct nft_set *set, struct nft_bitmap_elem *this,
94 const struct nft_bitmap *priv = nft_set_priv(set);
95 struct nft_bitmap_elem *be;
97 list_for_each_entry_rcu(be, &priv->list, head) {
98 if (memcmp(nft_set_ext_key(&be->ext),
99 nft_set_ext_key(&this->ext), set->klen) ||
100 !nft_set_elem_active(&be->ext, genmask))
108 static struct nft_elem_priv *
109 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_elem_priv **elem_priv)
130 struct nft_bitmap_elem *new = nft_elem_priv_cast(elem->priv), *be;
131 struct nft_bitmap *priv = nft_set_priv(set);
132 u8 genmask = nft_genmask_next(net);
135 be = nft_bitmap_elem_find(set, new, genmask);
137 *elem_priv = &be->priv;
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, const struct nft_set *set,
150 struct nft_elem_priv *elem_priv)
152 struct nft_bitmap_elem *be = nft_elem_priv_cast(elem_priv);
153 struct nft_bitmap *priv = nft_set_priv(set);
154 u8 genmask = nft_genmask_next(net);
157 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
158 /* Enter 00 state. */
159 priv->bitmap[idx] &= ~(genmask << off);
160 list_del_rcu(&be->head);
163 static void nft_bitmap_activate(const struct net *net,
164 const struct nft_set *set,
165 struct nft_elem_priv *elem_priv)
167 struct nft_bitmap_elem *be = nft_elem_priv_cast(elem_priv);
168 struct nft_bitmap *priv = nft_set_priv(set);
169 u8 genmask = nft_genmask_next(net);
172 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
173 /* Enter 11 state. */
174 priv->bitmap[idx] |= (genmask << off);
175 nft_clear(net, &be->ext);
178 static void nft_bitmap_flush(const struct net *net,
179 const struct nft_set *set,
180 struct nft_elem_priv *elem_priv)
182 struct nft_bitmap_elem *be = nft_elem_priv_cast(elem_priv);
183 struct nft_bitmap *priv = nft_set_priv(set);
184 u8 genmask = nft_genmask_next(net);
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);
193 static struct nft_elem_priv *
194 nft_bitmap_deactivate(const struct net *net, const struct nft_set *set,
195 const struct nft_set_elem *elem)
197 struct nft_bitmap_elem *this = nft_elem_priv_cast(elem->priv), *be;
198 struct nft_bitmap *priv = nft_set_priv(set);
199 u8 genmask = nft_genmask_next(net);
202 nft_bitmap_location(set, elem->key.val.data, &idx, &off);
204 be = nft_bitmap_elem_find(set, this, genmask);
208 /* Enter 10 state. */
209 priv->bitmap[idx] &= ~(genmask << off);
210 nft_set_elem_change_active(net, set, &be->ext);
215 static void nft_bitmap_walk(const struct nft_ctx *ctx,
217 struct nft_set_iter *iter)
219 const struct nft_bitmap *priv = nft_set_priv(set);
220 struct nft_bitmap_elem *be;
222 list_for_each_entry_rcu(be, &priv->list, head) {
223 if (iter->count < iter->skip)
226 iter->err = iter->fn(ctx, set, iter, &be->priv);
235 /* The bitmap size is pow(2, key length in bits) / bits per byte. This is
236 * multiplied by two since each element takes two bits. For 8 bit keys, the
237 * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
239 static inline u32 nft_bitmap_size(u32 klen)
241 return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
244 static inline u64 nft_bitmap_total_size(u32 klen)
246 return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
249 static u64 nft_bitmap_privsize(const struct nlattr * const nla[],
250 const struct nft_set_desc *desc)
252 u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
254 return nft_bitmap_total_size(klen);
257 static int nft_bitmap_init(const struct nft_set *set,
258 const struct nft_set_desc *desc,
259 const struct nlattr * const nla[])
261 struct nft_bitmap *priv = nft_set_priv(set);
263 BUILD_BUG_ON(offsetof(struct nft_bitmap_elem, priv) != 0);
265 INIT_LIST_HEAD(&priv->list);
266 priv->bitmap_size = nft_bitmap_size(set->klen);
271 static void nft_bitmap_destroy(const struct nft_ctx *ctx,
272 const struct nft_set *set)
274 struct nft_bitmap *priv = nft_set_priv(set);
275 struct nft_bitmap_elem *be, *n;
277 list_for_each_entry_safe(be, n, &priv->list, head)
278 nf_tables_set_elem_destroy(ctx, set, &be->priv);
281 static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
282 struct nft_set_estimate *est)
284 /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
290 est->size = nft_bitmap_total_size(desc->klen);
291 est->lookup = NFT_SET_CLASS_O_1;
292 est->space = NFT_SET_CLASS_O_1;
297 const struct nft_set_type nft_set_bitmap_type = {
299 .privsize = nft_bitmap_privsize,
300 .elemsize = offsetof(struct nft_bitmap_elem, ext),
301 .estimate = nft_bitmap_estimate,
302 .init = nft_bitmap_init,
303 .destroy = nft_bitmap_destroy,
304 .insert = nft_bitmap_insert,
305 .remove = nft_bitmap_remove,
306 .deactivate = nft_bitmap_deactivate,
307 .flush = nft_bitmap_flush,
308 .activate = nft_bitmap_activate,
309 .lookup = nft_bitmap_lookup,
310 .walk = nft_bitmap_walk,
311 .get = nft_bitmap_get,