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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
16struct nft_jhash {
17 u8 sreg;
18 u8 dreg;
19 u8 len;
20 bool autogen_seed:1;
21 u32 modulus;
22 u32 seed;
23 u32 offset;
24};
25
26static 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 = ®s->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
40struct nft_symhash {
41 u8 dreg;
42 u32 modulus;
43 u32 offset;
44};
45
46static 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
59static 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
69static 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 err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len);
87 if (err < 0)
88 return err;
89 if (len == 0)
90 return -ERANGE;
91
92 priv->len = len;
93
94 err = nft_parse_register_load(tb[NFTA_HASH_SREG], &priv->sreg, len);
95 if (err < 0)
96 return err;
97
98 priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
99 if (priv->modulus < 1)
100 return -ERANGE;
101
102 if (priv->offset + priv->modulus - 1 < priv->offset)
103 return -EOVERFLOW;
104
105 if (tb[NFTA_HASH_SEED]) {
106 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
107 } else {
108 priv->autogen_seed = true;
109 get_random_bytes(&priv->seed, sizeof(priv->seed));
110 }
111
112 return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG], &priv->dreg,
113 NULL, NFT_DATA_VALUE, sizeof(u32));
114}
115
116static 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->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
130 if (priv->modulus < 1)
131 return -ERANGE;
132
133 if (priv->offset + priv->modulus - 1 < priv->offset)
134 return -EOVERFLOW;
135
136 return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG],
137 &priv->dreg, NULL, NFT_DATA_VALUE,
138 sizeof(u32));
139}
140
141static int nft_jhash_dump(struct sk_buff *skb,
142 const struct nft_expr *expr)
143{
144 const struct nft_jhash *priv = nft_expr_priv(expr);
145
146 if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
147 goto nla_put_failure;
148 if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
149 goto nla_put_failure;
150 if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
151 goto nla_put_failure;
152 if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
153 goto nla_put_failure;
154 if (!priv->autogen_seed &&
155 nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
156 goto nla_put_failure;
157 if (priv->offset != 0)
158 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
159 goto nla_put_failure;
160 if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS)))
161 goto nla_put_failure;
162 return 0;
163
164nla_put_failure:
165 return -1;
166}
167
168static int nft_symhash_dump(struct sk_buff *skb,
169 const struct nft_expr *expr)
170{
171 const struct nft_symhash *priv = nft_expr_priv(expr);
172
173 if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
174 goto nla_put_failure;
175 if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
176 goto nla_put_failure;
177 if (priv->offset != 0)
178 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
179 goto nla_put_failure;
180 if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
181 goto nla_put_failure;
182 return 0;
183
184nla_put_failure:
185 return -1;
186}
187
188static struct nft_expr_type nft_hash_type;
189static const struct nft_expr_ops nft_jhash_ops = {
190 .type = &nft_hash_type,
191 .size = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
192 .eval = nft_jhash_eval,
193 .init = nft_jhash_init,
194 .dump = nft_jhash_dump,
195};
196
197static const struct nft_expr_ops nft_symhash_ops = {
198 .type = &nft_hash_type,
199 .size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
200 .eval = nft_symhash_eval,
201 .init = nft_symhash_init,
202 .dump = nft_symhash_dump,
203};
204
205static const struct nft_expr_ops *
206nft_hash_select_ops(const struct nft_ctx *ctx,
207 const struct nlattr * const tb[])
208{
209 u32 type;
210
211 if (!tb[NFTA_HASH_TYPE])
212 return &nft_jhash_ops;
213
214 type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
215 switch (type) {
216 case NFT_HASH_SYM:
217 return &nft_symhash_ops;
218 case NFT_HASH_JENKINS:
219 return &nft_jhash_ops;
220 default:
221 break;
222 }
223 return ERR_PTR(-EOPNOTSUPP);
224}
225
226static struct nft_expr_type nft_hash_type __read_mostly = {
227 .name = "hash",
228 .select_ops = nft_hash_select_ops,
229 .policy = nft_hash_policy,
230 .maxattr = NFTA_HASH_MAX,
231 .owner = THIS_MODULE,
232};
233
234static int __init nft_hash_module_init(void)
235{
236 return nft_register_expr(&nft_hash_type);
237}
238
239static void __exit nft_hash_module_exit(void)
240{
241 nft_unregister_expr(&nft_hash_type);
242}
243
244module_init(nft_hash_module_init);
245module_exit(nft_hash_module_exit);
246
247MODULE_LICENSE("GPL");
248MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
249MODULE_ALIAS_NFT_EXPR("hash");
250MODULE_DESCRIPTION("Netfilter nftables hash module");