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_set_ext **ext)
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);
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_elem *be = nft_elem_priv_cast(elem->priv);
154 struct nft_bitmap *priv = nft_set_priv(set);
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_elem *be = nft_elem_priv_cast(elem->priv);
169 struct nft_bitmap *priv = nft_set_priv(set);
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 void nft_bitmap_flush(const struct net *net,
180 const struct nft_set *set,
181 struct nft_elem_priv *elem_priv)
183 struct nft_bitmap_elem *be = nft_elem_priv_cast(elem_priv);
184 struct nft_bitmap *priv = nft_set_priv(set);
185 u8 genmask = nft_genmask_next(net);
188 nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
189 /* Enter 10 state, similar to deactivation. */
190 priv->bitmap[idx] &= ~(genmask << off);
191 nft_set_elem_change_active(net, set, &be->ext);
194 static struct nft_elem_priv *
195 nft_bitmap_deactivate(const struct net *net, const struct nft_set *set,
196 const struct nft_set_elem *elem)
198 struct nft_bitmap_elem *this = nft_elem_priv_cast(elem->priv), *be;
199 struct nft_bitmap *priv = nft_set_priv(set);
200 u8 genmask = nft_genmask_next(net);
203 nft_bitmap_location(set, elem->key.val.data, &idx, &off);
205 be = nft_bitmap_elem_find(set, this, genmask);
209 /* Enter 10 state. */
210 priv->bitmap[idx] &= ~(genmask << off);
211 nft_set_elem_change_active(net, set, &be->ext);
216 static void nft_bitmap_walk(const struct nft_ctx *ctx,
218 struct nft_set_iter *iter)
220 const struct nft_bitmap *priv = nft_set_priv(set);
221 struct nft_bitmap_elem *be;
222 struct nft_set_elem elem;
224 list_for_each_entry_rcu(be, &priv->list, head) {
225 if (iter->count < iter->skip)
227 if (!nft_set_elem_active(&be->ext, iter->genmask))
230 elem.priv = &be->priv;
232 iter->err = iter->fn(ctx, set, iter, &elem);
241 /* The bitmap size is pow(2, key length in bits) / bits per byte. This is
242 * multiplied by two since each element takes two bits. For 8 bit keys, the
243 * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
245 static inline u32 nft_bitmap_size(u32 klen)
247 return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
250 static inline u64 nft_bitmap_total_size(u32 klen)
252 return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
255 static u64 nft_bitmap_privsize(const struct nlattr * const nla[],
256 const struct nft_set_desc *desc)
258 u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
260 return nft_bitmap_total_size(klen);
263 static int nft_bitmap_init(const struct nft_set *set,
264 const struct nft_set_desc *desc,
265 const struct nlattr * const nla[])
267 struct nft_bitmap *priv = nft_set_priv(set);
269 BUILD_BUG_ON(offsetof(struct nft_bitmap_elem, priv) != 0);
271 INIT_LIST_HEAD(&priv->list);
272 priv->bitmap_size = nft_bitmap_size(set->klen);
277 static void nft_bitmap_destroy(const struct nft_ctx *ctx,
278 const struct nft_set *set)
280 struct nft_bitmap *priv = nft_set_priv(set);
281 struct nft_bitmap_elem *be, *n;
283 list_for_each_entry_safe(be, n, &priv->list, head)
284 nf_tables_set_elem_destroy(ctx, set, &be->priv);
287 static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
288 struct nft_set_estimate *est)
290 /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
296 est->size = nft_bitmap_total_size(desc->klen);
297 est->lookup = NFT_SET_CLASS_O_1;
298 est->space = NFT_SET_CLASS_O_1;
303 const struct nft_set_type nft_set_bitmap_type = {
305 .privsize = nft_bitmap_privsize,
306 .elemsize = offsetof(struct nft_bitmap_elem, ext),
307 .estimate = nft_bitmap_estimate,
308 .init = nft_bitmap_init,
309 .destroy = nft_bitmap_destroy,
310 .insert = nft_bitmap_insert,
311 .remove = nft_bitmap_remove,
312 .deactivate = nft_bitmap_deactivate,
313 .flush = nft_bitmap_flush,
314 .activate = nft_bitmap_activate,
315 .lookup = nft_bitmap_lookup,
316 .walk = nft_bitmap_walk,
317 .get = nft_bitmap_get,