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Linux/net/netfilter/nft_hash.c

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  1 /*
  2  * Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
  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 
 10 #include <linux/kernel.h>
 11 #include <linux/init.h>
 12 #include <linux/module.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 #include <net/netfilter/nf_tables_core.h>
 18 #include <linux/jhash.h>
 19 
 20 struct nft_jhash {
 21         enum nft_registers      sreg:8;
 22         enum nft_registers      dreg:8;
 23         u8                      len;
 24         bool                    autogen_seed:1;
 25         u32                     modulus;
 26         u32                     seed;
 27         u32                     offset;
 28         struct nft_set          *map;
 29 };
 30 
 31 static void nft_jhash_eval(const struct nft_expr *expr,
 32                            struct nft_regs *regs,
 33                            const struct nft_pktinfo *pkt)
 34 {
 35         struct nft_jhash *priv = nft_expr_priv(expr);
 36         const void *data = &regs->data[priv->sreg];
 37         u32 h;
 38 
 39         h = reciprocal_scale(jhash(data, priv->len, priv->seed),
 40                              priv->modulus);
 41 
 42         regs->data[priv->dreg] = h + priv->offset;
 43 }
 44 
 45 static void nft_jhash_map_eval(const struct nft_expr *expr,
 46                                struct nft_regs *regs,
 47                                const struct nft_pktinfo *pkt)
 48 {
 49         struct nft_jhash *priv = nft_expr_priv(expr);
 50         const void *data = &regs->data[priv->sreg];
 51         const struct nft_set *map = priv->map;
 52         const struct nft_set_ext *ext;
 53         u32 result;
 54         bool found;
 55 
 56         result = reciprocal_scale(jhash(data, priv->len, priv->seed),
 57                                         priv->modulus) + priv->offset;
 58 
 59         found = map->ops->lookup(nft_net(pkt), map, &result, &ext);
 60         if (!found)
 61                 return;
 62 
 63         nft_data_copy(&regs->data[priv->dreg],
 64                       nft_set_ext_data(ext), map->dlen);
 65 }
 66 
 67 struct nft_symhash {
 68         enum nft_registers      dreg:8;
 69         u32                     modulus;
 70         u32                     offset;
 71         struct nft_set          *map;
 72 };
 73 
 74 static void nft_symhash_eval(const struct nft_expr *expr,
 75                              struct nft_regs *regs,
 76                              const struct nft_pktinfo *pkt)
 77 {
 78         struct nft_symhash *priv = nft_expr_priv(expr);
 79         struct sk_buff *skb = pkt->skb;
 80         u32 h;
 81 
 82         h = reciprocal_scale(__skb_get_hash_symmetric(skb), priv->modulus);
 83 
 84         regs->data[priv->dreg] = h + priv->offset;
 85 }
 86 
 87 static void nft_symhash_map_eval(const struct nft_expr *expr,
 88                                  struct nft_regs *regs,
 89                                  const struct nft_pktinfo *pkt)
 90 {
 91         struct nft_symhash *priv = nft_expr_priv(expr);
 92         struct sk_buff *skb = pkt->skb;
 93         const struct nft_set *map = priv->map;
 94         const struct nft_set_ext *ext;
 95         u32 result;
 96         bool found;
 97 
 98         result = reciprocal_scale(__skb_get_hash_symmetric(skb),
 99                                   priv->modulus) + priv->offset;
100 
101         found = map->ops->lookup(nft_net(pkt), map, &result, &ext);
102         if (!found)
103                 return;
104 
105         nft_data_copy(&regs->data[priv->dreg],
106                       nft_set_ext_data(ext), map->dlen);
107 }
108 
109 static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
110         [NFTA_HASH_SREG]        = { .type = NLA_U32 },
111         [NFTA_HASH_DREG]        = { .type = NLA_U32 },
112         [NFTA_HASH_LEN]         = { .type = NLA_U32 },
113         [NFTA_HASH_MODULUS]     = { .type = NLA_U32 },
114         [NFTA_HASH_SEED]        = { .type = NLA_U32 },
115         [NFTA_HASH_OFFSET]      = { .type = NLA_U32 },
116         [NFTA_HASH_TYPE]        = { .type = NLA_U32 },
117         [NFTA_HASH_SET_NAME]    = { .type = NLA_STRING,
118                                     .len = NFT_SET_MAXNAMELEN - 1 },
119         [NFTA_HASH_SET_ID]      = { .type = NLA_U32 },
120 };
121 
122 static int nft_jhash_init(const struct nft_ctx *ctx,
123                           const struct nft_expr *expr,
124                           const struct nlattr * const tb[])
125 {
126         struct nft_jhash *priv = nft_expr_priv(expr);
127         u32 len;
128         int err;
129 
130         if (!tb[NFTA_HASH_SREG] ||
131             !tb[NFTA_HASH_DREG] ||
132             !tb[NFTA_HASH_LEN]  ||
133             !tb[NFTA_HASH_MODULUS])
134                 return -EINVAL;
135 
136         if (tb[NFTA_HASH_OFFSET])
137                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
138 
139         priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
140         priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
141 
142         err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len);
143         if (err < 0)
144                 return err;
145         if (len == 0)
146                 return -ERANGE;
147 
148         priv->len = len;
149 
150         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
151         if (priv->modulus < 1)
152                 return -ERANGE;
153 
154         if (priv->offset + priv->modulus - 1 < priv->offset)
155                 return -EOVERFLOW;
156 
157         if (tb[NFTA_HASH_SEED]) {
158                 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
159         } else {
160                 priv->autogen_seed = true;
161                 get_random_bytes(&priv->seed, sizeof(priv->seed));
162         }
163 
164         return nft_validate_register_load(priv->sreg, len) &&
165                nft_validate_register_store(ctx, priv->dreg, NULL,
166                                            NFT_DATA_VALUE, sizeof(u32));
167 }
168 
169 static int nft_jhash_map_init(const struct nft_ctx *ctx,
170                               const struct nft_expr *expr,
171                               const struct nlattr * const tb[])
172 {
173         struct nft_jhash *priv = nft_expr_priv(expr);
174         u8 genmask = nft_genmask_next(ctx->net);
175 
176         nft_jhash_init(ctx, expr, tb);
177         priv->map = nft_set_lookup_global(ctx->net, ctx->table,
178                                           tb[NFTA_HASH_SET_NAME],
179                                           tb[NFTA_HASH_SET_ID], genmask);
180         return PTR_ERR_OR_ZERO(priv->map);
181 }
182 
183 static int nft_symhash_init(const struct nft_ctx *ctx,
184                             const struct nft_expr *expr,
185                             const struct nlattr * const tb[])
186 {
187         struct nft_symhash *priv = nft_expr_priv(expr);
188 
189         if (!tb[NFTA_HASH_DREG]    ||
190             !tb[NFTA_HASH_MODULUS])
191                 return -EINVAL;
192 
193         if (tb[NFTA_HASH_OFFSET])
194                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
195 
196         priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
197 
198         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
199         if (priv->modulus <= 1)
200                 return -ERANGE;
201 
202         if (priv->offset + priv->modulus - 1 < priv->offset)
203                 return -EOVERFLOW;
204 
205         return nft_validate_register_store(ctx, priv->dreg, NULL,
206                                            NFT_DATA_VALUE, sizeof(u32));
207 }
208 
209 static int nft_symhash_map_init(const struct nft_ctx *ctx,
210                                 const struct nft_expr *expr,
211                                 const struct nlattr * const tb[])
212 {
213         struct nft_jhash *priv = nft_expr_priv(expr);
214         u8 genmask = nft_genmask_next(ctx->net);
215 
216         nft_symhash_init(ctx, expr, tb);
217         priv->map = nft_set_lookup_global(ctx->net, ctx->table,
218                                           tb[NFTA_HASH_SET_NAME],
219                                           tb[NFTA_HASH_SET_ID], genmask);
220         return PTR_ERR_OR_ZERO(priv->map);
221 }
222 
223 static int nft_jhash_dump(struct sk_buff *skb,
224                           const struct nft_expr *expr)
225 {
226         const struct nft_jhash *priv = nft_expr_priv(expr);
227 
228         if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
229                 goto nla_put_failure;
230         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
231                 goto nla_put_failure;
232         if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
233                 goto nla_put_failure;
234         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
235                 goto nla_put_failure;
236         if (!priv->autogen_seed &&
237             nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
238                 goto nla_put_failure;
239         if (priv->offset != 0)
240                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
241                         goto nla_put_failure;
242         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS)))
243                 goto nla_put_failure;
244         return 0;
245 
246 nla_put_failure:
247         return -1;
248 }
249 
250 static int nft_jhash_map_dump(struct sk_buff *skb,
251                                const struct nft_expr *expr)
252 {
253         const struct nft_jhash *priv = nft_expr_priv(expr);
254 
255         if (nft_jhash_dump(skb, expr) ||
256             nla_put_string(skb, NFTA_HASH_SET_NAME, priv->map->name))
257                 return -1;
258 
259         return 0;
260 }
261 
262 static int nft_symhash_dump(struct sk_buff *skb,
263                             const struct nft_expr *expr)
264 {
265         const struct nft_symhash *priv = nft_expr_priv(expr);
266 
267         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
268                 goto nla_put_failure;
269         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
270                 goto nla_put_failure;
271         if (priv->offset != 0)
272                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
273                         goto nla_put_failure;
274         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
275                 goto nla_put_failure;
276         return 0;
277 
278 nla_put_failure:
279         return -1;
280 }
281 
282 static int nft_symhash_map_dump(struct sk_buff *skb,
283                                 const struct nft_expr *expr)
284 {
285         const struct nft_symhash *priv = nft_expr_priv(expr);
286 
287         if (nft_symhash_dump(skb, expr) ||
288             nla_put_string(skb, NFTA_HASH_SET_NAME, priv->map->name))
289                 return -1;
290 
291         return 0;
292 }
293 
294 static struct nft_expr_type nft_hash_type;
295 static const struct nft_expr_ops nft_jhash_ops = {
296         .type           = &nft_hash_type,
297         .size           = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
298         .eval           = nft_jhash_eval,
299         .init           = nft_jhash_init,
300         .dump           = nft_jhash_dump,
301 };
302 
303 static const struct nft_expr_ops nft_jhash_map_ops = {
304         .type           = &nft_hash_type,
305         .size           = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
306         .eval           = nft_jhash_map_eval,
307         .init           = nft_jhash_map_init,
308         .dump           = nft_jhash_map_dump,
309 };
310 
311 static const struct nft_expr_ops nft_symhash_ops = {
312         .type           = &nft_hash_type,
313         .size           = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
314         .eval           = nft_symhash_eval,
315         .init           = nft_symhash_init,
316         .dump           = nft_symhash_dump,
317 };
318 
319 static const struct nft_expr_ops nft_symhash_map_ops = {
320         .type           = &nft_hash_type,
321         .size           = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
322         .eval           = nft_symhash_map_eval,
323         .init           = nft_symhash_map_init,
324         .dump           = nft_symhash_map_dump,
325 };
326 
327 static const struct nft_expr_ops *
328 nft_hash_select_ops(const struct nft_ctx *ctx,
329                     const struct nlattr * const tb[])
330 {
331         u32 type;
332 
333         if (!tb[NFTA_HASH_TYPE])
334                 return &nft_jhash_ops;
335 
336         type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
337         switch (type) {
338         case NFT_HASH_SYM:
339                 if (tb[NFTA_HASH_SET_NAME])
340                         return &nft_symhash_map_ops;
341                 return &nft_symhash_ops;
342         case NFT_HASH_JENKINS:
343                 if (tb[NFTA_HASH_SET_NAME])
344                         return &nft_jhash_map_ops;
345                 return &nft_jhash_ops;
346         default:
347                 break;
348         }
349         return ERR_PTR(-EOPNOTSUPP);
350 }
351 
352 static struct nft_expr_type nft_hash_type __read_mostly = {
353         .name           = "hash",
354         .select_ops     = nft_hash_select_ops,
355         .policy         = nft_hash_policy,
356         .maxattr        = NFTA_HASH_MAX,
357         .owner          = THIS_MODULE,
358 };
359 
360 static int __init nft_hash_module_init(void)
361 {
362         return nft_register_expr(&nft_hash_type);
363 }
364 
365 static void __exit nft_hash_module_exit(void)
366 {
367         nft_unregister_expr(&nft_hash_type);
368 }
369 
370 module_init(nft_hash_module_init);
371 module_exit(nft_hash_module_exit);
372 
373 MODULE_LICENSE("GPL");
374 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
375 MODULE_ALIAS_NFT_EXPR("hash");
376 

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