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Linux/net/netfilter/nft_hash.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
  4  */
  5 
  6 #include <linux/kernel.h>
  7 #include <linux/init.h>
  8 #include <linux/module.h>
  9 #include <linux/netlink.h>
 10 #include <linux/netfilter.h>
 11 #include <linux/netfilter/nf_tables.h>
 12 #include <net/netfilter/nf_tables.h>
 13 #include <net/netfilter/nf_tables_core.h>
 14 #include <linux/jhash.h>
 15 
 16 struct nft_jhash {
 17         enum nft_registers      sreg:8;
 18         enum nft_registers      dreg:8;
 19         u8                      len;
 20         bool                    autogen_seed:1;
 21         u32                     modulus;
 22         u32                     seed;
 23         u32                     offset;
 24 };
 25 
 26 static void nft_jhash_eval(const struct nft_expr *expr,
 27                            struct nft_regs *regs,
 28                            const struct nft_pktinfo *pkt)
 29 {
 30         struct nft_jhash *priv = nft_expr_priv(expr);
 31         const void *data = &regs->data[priv->sreg];
 32         u32 h;
 33 
 34         h = reciprocal_scale(jhash(data, priv->len, priv->seed),
 35                              priv->modulus);
 36 
 37         regs->data[priv->dreg] = h + priv->offset;
 38 }
 39 
 40 struct nft_symhash {
 41         enum nft_registers      dreg:8;
 42         u32                     modulus;
 43         u32                     offset;
 44 };
 45 
 46 static void nft_symhash_eval(const struct nft_expr *expr,
 47                              struct nft_regs *regs,
 48                              const struct nft_pktinfo *pkt)
 49 {
 50         struct nft_symhash *priv = nft_expr_priv(expr);
 51         struct sk_buff *skb = pkt->skb;
 52         u32 h;
 53 
 54         h = reciprocal_scale(__skb_get_hash_symmetric(skb), priv->modulus);
 55 
 56         regs->data[priv->dreg] = h + priv->offset;
 57 }
 58 
 59 static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
 60         [NFTA_HASH_SREG]        = { .type = NLA_U32 },
 61         [NFTA_HASH_DREG]        = { .type = NLA_U32 },
 62         [NFTA_HASH_LEN]         = { .type = NLA_U32 },
 63         [NFTA_HASH_MODULUS]     = { .type = NLA_U32 },
 64         [NFTA_HASH_SEED]        = { .type = NLA_U32 },
 65         [NFTA_HASH_OFFSET]      = { .type = NLA_U32 },
 66         [NFTA_HASH_TYPE]        = { .type = NLA_U32 },
 67 };
 68 
 69 static int nft_jhash_init(const struct nft_ctx *ctx,
 70                           const struct nft_expr *expr,
 71                           const struct nlattr * const tb[])
 72 {
 73         struct nft_jhash *priv = nft_expr_priv(expr);
 74         u32 len;
 75         int err;
 76 
 77         if (!tb[NFTA_HASH_SREG] ||
 78             !tb[NFTA_HASH_DREG] ||
 79             !tb[NFTA_HASH_LEN]  ||
 80             !tb[NFTA_HASH_MODULUS])
 81                 return -EINVAL;
 82 
 83         if (tb[NFTA_HASH_OFFSET])
 84                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
 85 
 86         priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
 87         priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
 88 
 89         err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len);
 90         if (err < 0)
 91                 return err;
 92         if (len == 0)
 93                 return -ERANGE;
 94 
 95         priv->len = len;
 96 
 97         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
 98         if (priv->modulus < 1)
 99                 return -ERANGE;
100 
101         if (priv->offset + priv->modulus - 1 < priv->offset)
102                 return -EOVERFLOW;
103 
104         if (tb[NFTA_HASH_SEED]) {
105                 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
106         } else {
107                 priv->autogen_seed = true;
108                 get_random_bytes(&priv->seed, sizeof(priv->seed));
109         }
110 
111         return nft_validate_register_load(priv->sreg, len) &&
112                nft_validate_register_store(ctx, priv->dreg, NULL,
113                                            NFT_DATA_VALUE, sizeof(u32));
114 }
115 
116 static int nft_symhash_init(const struct nft_ctx *ctx,
117                             const struct nft_expr *expr,
118                             const struct nlattr * const tb[])
119 {
120         struct nft_symhash *priv = nft_expr_priv(expr);
121 
122         if (!tb[NFTA_HASH_DREG]    ||
123             !tb[NFTA_HASH_MODULUS])
124                 return -EINVAL;
125 
126         if (tb[NFTA_HASH_OFFSET])
127                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
128 
129         priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
130 
131         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
132         if (priv->modulus < 1)
133                 return -ERANGE;
134 
135         if (priv->offset + priv->modulus - 1 < priv->offset)
136                 return -EOVERFLOW;
137 
138         return nft_validate_register_store(ctx, priv->dreg, NULL,
139                                            NFT_DATA_VALUE, sizeof(u32));
140 }
141 
142 static int nft_jhash_dump(struct sk_buff *skb,
143                           const struct nft_expr *expr)
144 {
145         const struct nft_jhash *priv = nft_expr_priv(expr);
146 
147         if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
148                 goto nla_put_failure;
149         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
150                 goto nla_put_failure;
151         if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
152                 goto nla_put_failure;
153         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
154                 goto nla_put_failure;
155         if (!priv->autogen_seed &&
156             nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
157                 goto nla_put_failure;
158         if (priv->offset != 0)
159                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
160                         goto nla_put_failure;
161         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS)))
162                 goto nla_put_failure;
163         return 0;
164 
165 nla_put_failure:
166         return -1;
167 }
168 
169 static int nft_symhash_dump(struct sk_buff *skb,
170                             const struct nft_expr *expr)
171 {
172         const struct nft_symhash *priv = nft_expr_priv(expr);
173 
174         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
175                 goto nla_put_failure;
176         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
177                 goto nla_put_failure;
178         if (priv->offset != 0)
179                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
180                         goto nla_put_failure;
181         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
182                 goto nla_put_failure;
183         return 0;
184 
185 nla_put_failure:
186         return -1;
187 }
188 
189 static struct nft_expr_type nft_hash_type;
190 static const struct nft_expr_ops nft_jhash_ops = {
191         .type           = &nft_hash_type,
192         .size           = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
193         .eval           = nft_jhash_eval,
194         .init           = nft_jhash_init,
195         .dump           = nft_jhash_dump,
196 };
197 
198 static const struct nft_expr_ops nft_symhash_ops = {
199         .type           = &nft_hash_type,
200         .size           = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
201         .eval           = nft_symhash_eval,
202         .init           = nft_symhash_init,
203         .dump           = nft_symhash_dump,
204 };
205 
206 static const struct nft_expr_ops *
207 nft_hash_select_ops(const struct nft_ctx *ctx,
208                     const struct nlattr * const tb[])
209 {
210         u32 type;
211 
212         if (!tb[NFTA_HASH_TYPE])
213                 return &nft_jhash_ops;
214 
215         type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
216         switch (type) {
217         case NFT_HASH_SYM:
218                 return &nft_symhash_ops;
219         case NFT_HASH_JENKINS:
220                 return &nft_jhash_ops;
221         default:
222                 break;
223         }
224         return ERR_PTR(-EOPNOTSUPP);
225 }
226 
227 static struct nft_expr_type nft_hash_type __read_mostly = {
228         .name           = "hash",
229         .select_ops     = nft_hash_select_ops,
230         .policy         = nft_hash_policy,
231         .maxattr        = NFTA_HASH_MAX,
232         .owner          = THIS_MODULE,
233 };
234 
235 static int __init nft_hash_module_init(void)
236 {
237         return nft_register_expr(&nft_hash_type);
238 }
239 
240 static void __exit nft_hash_module_exit(void)
241 {
242         nft_unregister_expr(&nft_hash_type);
243 }
244 
245 module_init(nft_hash_module_init);
246 module_exit(nft_hash_module_exit);
247 
248 MODULE_LICENSE("GPL");
249 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
250 MODULE_ALIAS_NFT_EXPR("hash");
251 MODULE_DESCRIPTION("Netfilter nftables hash module");
252 

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