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665153ff PNA |
1 | /* |
2 | * Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org> | |
3 | * | |
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. | |
7 | */ | |
8 | ||
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> | |
17 | ||
e920dde5 PNA |
18 | struct nft_bitmap_elem { |
19 | struct list_head head; | |
20 | struct nft_set_ext ext; | |
21 | }; | |
22 | ||
665153ff PNA |
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. | |
25 | * | |
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 | |
29 | * state: | |
30 | * | |
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. | |
35 | * | |
36 | * On transaction handling, we observe these two temporary states: | |
37 | * | |
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. | |
47 | */ | |
48 | struct nft_bitmap { | |
e920dde5 PNA |
49 | struct list_head list; |
50 | u16 bitmap_size; | |
51 | u8 bitmap[]; | |
665153ff PNA |
52 | }; |
53 | ||
fd89b23a LZ |
54 | static inline void nft_bitmap_location(const struct nft_set *set, |
55 | const void *key, | |
56 | u32 *idx, u32 *off) | |
665153ff | 57 | { |
fd89b23a LZ |
58 | u32 k; |
59 | ||
60 | if (set->klen == 2) | |
61 | k = *(u16 *)key; | |
62 | else | |
63 | k = *(u8 *)key; | |
64 | k <<= 1; | |
665153ff PNA |
65 | |
66 | *idx = k / BITS_PER_BYTE; | |
67 | *off = k % BITS_PER_BYTE; | |
68 | } | |
69 | ||
70 | /* Fetch the two bits that represent the element and check if it is active based | |
71 | * on the generation mask. | |
72 | */ | |
73 | static inline bool | |
74 | nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask) | |
75 | { | |
76 | return (bitmap[idx] & (0x3 << off)) & (genmask << off); | |
77 | } | |
78 | ||
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) | |
81 | { | |
82 | const struct nft_bitmap *priv = nft_set_priv(set); | |
83 | u8 genmask = nft_genmask_cur(net); | |
84 | u32 idx, off; | |
85 | ||
fd89b23a | 86 | nft_bitmap_location(set, key, &idx, &off); |
665153ff PNA |
87 | |
88 | return nft_bitmap_active(priv->bitmap, idx, off, genmask); | |
89 | } | |
90 | ||
e920dde5 PNA |
91 | static struct nft_bitmap_elem * |
92 | nft_bitmap_elem_find(const struct nft_set *set, struct nft_bitmap_elem *this, | |
93 | u8 genmask) | |
94 | { | |
95 | const struct nft_bitmap *priv = nft_set_priv(set); | |
96 | struct nft_bitmap_elem *be; | |
97 | ||
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)) | |
102 | continue; | |
103 | ||
104 | return be; | |
105 | } | |
106 | return NULL; | |
107 | } | |
108 | ||
665153ff PNA |
109 | static int nft_bitmap_insert(const struct net *net, const struct nft_set *set, |
110 | const struct nft_set_elem *elem, | |
e920dde5 | 111 | struct nft_set_ext **ext) |
665153ff PNA |
112 | { |
113 | struct nft_bitmap *priv = nft_set_priv(set); | |
e920dde5 | 114 | struct nft_bitmap_elem *new = elem->priv, *be; |
665153ff PNA |
115 | u8 genmask = nft_genmask_next(net); |
116 | u32 idx, off; | |
117 | ||
e920dde5 PNA |
118 | be = nft_bitmap_elem_find(set, new, genmask); |
119 | if (be) { | |
120 | *ext = &be->ext; | |
665153ff | 121 | return -EEXIST; |
e920dde5 | 122 | } |
665153ff | 123 | |
e920dde5 | 124 | nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off); |
665153ff PNA |
125 | /* Enter 01 state. */ |
126 | priv->bitmap[idx] |= (genmask << off); | |
e920dde5 | 127 | list_add_tail_rcu(&new->head, &priv->list); |
665153ff PNA |
128 | |
129 | return 0; | |
130 | } | |
131 | ||
132 | static void nft_bitmap_remove(const struct net *net, | |
133 | const struct nft_set *set, | |
134 | const struct nft_set_elem *elem) | |
135 | { | |
136 | struct nft_bitmap *priv = nft_set_priv(set); | |
e920dde5 | 137 | struct nft_bitmap_elem *be = elem->priv; |
665153ff PNA |
138 | u8 genmask = nft_genmask_next(net); |
139 | u32 idx, off; | |
140 | ||
e920dde5 | 141 | nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off); |
665153ff PNA |
142 | /* Enter 00 state. */ |
143 | priv->bitmap[idx] &= ~(genmask << off); | |
e920dde5 | 144 | list_del_rcu(&be->head); |
665153ff PNA |
145 | } |
146 | ||
147 | static void nft_bitmap_activate(const struct net *net, | |
148 | const struct nft_set *set, | |
149 | const struct nft_set_elem *elem) | |
150 | { | |
151 | struct nft_bitmap *priv = nft_set_priv(set); | |
e920dde5 | 152 | struct nft_bitmap_elem *be = elem->priv; |
665153ff PNA |
153 | u8 genmask = nft_genmask_next(net); |
154 | u32 idx, off; | |
155 | ||
e920dde5 | 156 | nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off); |
665153ff PNA |
157 | /* Enter 11 state. */ |
158 | priv->bitmap[idx] |= (genmask << off); | |
e920dde5 | 159 | nft_set_elem_change_active(net, set, &be->ext); |
665153ff PNA |
160 | } |
161 | ||
162 | static bool nft_bitmap_flush(const struct net *net, | |
e920dde5 | 163 | const struct nft_set *set, void *_be) |
665153ff PNA |
164 | { |
165 | struct nft_bitmap *priv = nft_set_priv(set); | |
166 | u8 genmask = nft_genmask_next(net); | |
e920dde5 | 167 | struct nft_bitmap_elem *be = _be; |
665153ff PNA |
168 | u32 idx, off; |
169 | ||
e920dde5 | 170 | nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off); |
665153ff PNA |
171 | /* Enter 10 state, similar to deactivation. */ |
172 | priv->bitmap[idx] &= ~(genmask << off); | |
e920dde5 | 173 | nft_set_elem_change_active(net, set, &be->ext); |
665153ff PNA |
174 | |
175 | return true; | |
176 | } | |
177 | ||
665153ff PNA |
178 | static void *nft_bitmap_deactivate(const struct net *net, |
179 | const struct nft_set *set, | |
180 | const struct nft_set_elem *elem) | |
181 | { | |
182 | struct nft_bitmap *priv = nft_set_priv(set); | |
e920dde5 | 183 | struct nft_bitmap_elem *this = elem->priv, *be; |
665153ff | 184 | u8 genmask = nft_genmask_next(net); |
fd89b23a | 185 | u32 idx, off; |
665153ff | 186 | |
fd89b23a | 187 | nft_bitmap_location(set, elem->key.val.data, &idx, &off); |
665153ff | 188 | |
e920dde5 PNA |
189 | be = nft_bitmap_elem_find(set, this, genmask); |
190 | if (!be) | |
665153ff PNA |
191 | return NULL; |
192 | ||
193 | /* Enter 10 state. */ | |
194 | priv->bitmap[idx] &= ~(genmask << off); | |
e920dde5 | 195 | nft_set_elem_change_active(net, set, &be->ext); |
665153ff | 196 | |
e920dde5 | 197 | return be; |
665153ff PNA |
198 | } |
199 | ||
200 | static void nft_bitmap_walk(const struct nft_ctx *ctx, | |
201 | struct nft_set *set, | |
202 | struct nft_set_iter *iter) | |
203 | { | |
204 | const struct nft_bitmap *priv = nft_set_priv(set); | |
e920dde5 | 205 | struct nft_bitmap_elem *be; |
665153ff | 206 | struct nft_set_elem elem; |
e920dde5 PNA |
207 | |
208 | list_for_each_entry_rcu(be, &priv->list, head) { | |
209 | if (iter->count < iter->skip) | |
210 | goto cont; | |
211 | if (!nft_set_elem_active(&be->ext, iter->genmask)) | |
212 | goto cont; | |
213 | ||
214 | elem.priv = be; | |
215 | ||
216 | iter->err = iter->fn(ctx, set, iter, &elem); | |
217 | ||
218 | if (iter->err < 0) | |
219 | return; | |
665153ff | 220 | cont: |
e920dde5 | 221 | iter->count++; |
665153ff PNA |
222 | } |
223 | } | |
224 | ||
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. | |
228 | */ | |
229 | static inline u32 nft_bitmap_size(u32 klen) | |
230 | { | |
231 | return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1; | |
232 | } | |
233 | ||
234 | static inline u32 nft_bitmap_total_size(u32 klen) | |
235 | { | |
236 | return sizeof(struct nft_bitmap) + nft_bitmap_size(klen); | |
237 | } | |
238 | ||
347b408d PNA |
239 | static unsigned int nft_bitmap_privsize(const struct nlattr * const nla[], |
240 | const struct nft_set_desc *desc) | |
665153ff PNA |
241 | { |
242 | u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN])); | |
243 | ||
244 | return nft_bitmap_total_size(klen); | |
245 | } | |
246 | ||
247 | static int nft_bitmap_init(const struct nft_set *set, | |
248 | const struct nft_set_desc *desc, | |
249 | const struct nlattr * const nla[]) | |
250 | { | |
251 | struct nft_bitmap *priv = nft_set_priv(set); | |
252 | ||
e920dde5 | 253 | INIT_LIST_HEAD(&priv->list); |
13aa5a8f | 254 | priv->bitmap_size = nft_bitmap_size(set->klen); |
665153ff PNA |
255 | |
256 | return 0; | |
257 | } | |
258 | ||
259 | static void nft_bitmap_destroy(const struct nft_set *set) | |
260 | { | |
54a5f9d9 LZ |
261 | struct nft_bitmap *priv = nft_set_priv(set); |
262 | struct nft_bitmap_elem *be, *n; | |
263 | ||
264 | list_for_each_entry_safe(be, n, &priv->list, head) | |
265 | nft_set_elem_destroy(set, be, true); | |
665153ff PNA |
266 | } |
267 | ||
268 | static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features, | |
269 | struct nft_set_estimate *est) | |
270 | { | |
271 | /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */ | |
272 | if (desc->klen > 2) | |
273 | return false; | |
274 | ||
275 | est->size = nft_bitmap_total_size(desc->klen); | |
276 | est->lookup = NFT_SET_CLASS_O_1; | |
277 | est->space = NFT_SET_CLASS_O_1; | |
278 | ||
279 | return true; | |
280 | } | |
281 | ||
2b664957 | 282 | static struct nft_set_type nft_bitmap_type; |
665153ff | 283 | static struct nft_set_ops nft_bitmap_ops __read_mostly = { |
2b664957 | 284 | .type = &nft_bitmap_type, |
665153ff | 285 | .privsize = nft_bitmap_privsize, |
e920dde5 | 286 | .elemsize = offsetof(struct nft_bitmap_elem, ext), |
665153ff PNA |
287 | .estimate = nft_bitmap_estimate, |
288 | .init = nft_bitmap_init, | |
289 | .destroy = nft_bitmap_destroy, | |
290 | .insert = nft_bitmap_insert, | |
291 | .remove = nft_bitmap_remove, | |
292 | .deactivate = nft_bitmap_deactivate, | |
293 | .flush = nft_bitmap_flush, | |
294 | .activate = nft_bitmap_activate, | |
295 | .lookup = nft_bitmap_lookup, | |
296 | .walk = nft_bitmap_walk, | |
2b664957 PNA |
297 | }; |
298 | ||
299 | static struct nft_set_type nft_bitmap_type __read_mostly = { | |
300 | .ops = &nft_bitmap_ops, | |
665153ff PNA |
301 | .owner = THIS_MODULE, |
302 | }; | |
303 | ||
304 | static int __init nft_bitmap_module_init(void) | |
305 | { | |
2b664957 | 306 | return nft_register_set(&nft_bitmap_type); |
665153ff PNA |
307 | } |
308 | ||
309 | static void __exit nft_bitmap_module_exit(void) | |
310 | { | |
2b664957 | 311 | nft_unregister_set(&nft_bitmap_type); |
665153ff PNA |
312 | } |
313 | ||
314 | module_init(nft_bitmap_module_init); | |
315 | module_exit(nft_bitmap_module_exit); | |
316 | ||
317 | MODULE_LICENSE("GPL"); | |
318 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); | |
319 | MODULE_ALIAS_NFT_SET(); |