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cb1b69b0 LGL |
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_hash { | |
21 | enum nft_registers sreg:8; | |
22 | enum nft_registers dreg:8; | |
23 | u8 len; | |
24 | u32 modulus; | |
25 | u32 seed; | |
70ca767e | 26 | u32 offset; |
cb1b69b0 LGL |
27 | }; |
28 | ||
29 | static void nft_hash_eval(const struct nft_expr *expr, | |
30 | struct nft_regs *regs, | |
31 | const struct nft_pktinfo *pkt) | |
32 | { | |
33 | struct nft_hash *priv = nft_expr_priv(expr); | |
34 | const void *data = ®s->data[priv->sreg]; | |
70ca767e | 35 | u32 h; |
cb1b69b0 | 36 | |
70ca767e LGL |
37 | h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus); |
38 | regs->data[priv->dreg] = h + priv->offset; | |
cb1b69b0 LGL |
39 | } |
40 | ||
a5e57336 | 41 | static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = { |
cb1b69b0 LGL |
42 | [NFTA_HASH_SREG] = { .type = NLA_U32 }, |
43 | [NFTA_HASH_DREG] = { .type = NLA_U32 }, | |
44 | [NFTA_HASH_LEN] = { .type = NLA_U32 }, | |
45 | [NFTA_HASH_MODULUS] = { .type = NLA_U32 }, | |
46 | [NFTA_HASH_SEED] = { .type = NLA_U32 }, | |
5751e175 | 47 | [NFTA_HASH_OFFSET] = { .type = NLA_U32 }, |
cb1b69b0 LGL |
48 | }; |
49 | ||
50 | static int nft_hash_init(const struct nft_ctx *ctx, | |
51 | const struct nft_expr *expr, | |
52 | const struct nlattr * const tb[]) | |
53 | { | |
54 | struct nft_hash *priv = nft_expr_priv(expr); | |
55 | u32 len; | |
abd66e9f | 56 | int err; |
cb1b69b0 LGL |
57 | |
58 | if (!tb[NFTA_HASH_SREG] || | |
59 | !tb[NFTA_HASH_DREG] || | |
60 | !tb[NFTA_HASH_LEN] || | |
cb1b69b0 LGL |
61 | !tb[NFTA_HASH_MODULUS]) |
62 | return -EINVAL; | |
63 | ||
70ca767e LGL |
64 | if (tb[NFTA_HASH_OFFSET]) |
65 | priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET])); | |
66 | ||
cb1b69b0 LGL |
67 | priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]); |
68 | priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]); | |
69 | ||
abd66e9f LGL |
70 | err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len); |
71 | if (err < 0) | |
72 | return err; | |
73 | if (len == 0) | |
cb1b69b0 LGL |
74 | return -ERANGE; |
75 | ||
76 | priv->len = len; | |
77 | ||
78 | priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); | |
79 | if (priv->modulus <= 1) | |
80 | return -ERANGE; | |
81 | ||
14e2dee0 | 82 | if (priv->offset + priv->modulus - 1 < priv->offset) |
70ca767e LGL |
83 | return -EOVERFLOW; |
84 | ||
f86dab3a PNA |
85 | if (tb[NFTA_HASH_SEED]) |
86 | priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED])); | |
87 | else | |
88 | get_random_bytes(&priv->seed, sizeof(priv->seed)); | |
cb1b69b0 LGL |
89 | |
90 | return nft_validate_register_load(priv->sreg, len) && | |
91 | nft_validate_register_store(ctx, priv->dreg, NULL, | |
92 | NFT_DATA_VALUE, sizeof(u32)); | |
93 | } | |
94 | ||
95 | static int nft_hash_dump(struct sk_buff *skb, | |
96 | const struct nft_expr *expr) | |
97 | { | |
98 | const struct nft_hash *priv = nft_expr_priv(expr); | |
99 | ||
100 | if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg)) | |
101 | goto nla_put_failure; | |
102 | if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg)) | |
103 | goto nla_put_failure; | |
7073b16f | 104 | if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len))) |
cb1b69b0 | 105 | goto nla_put_failure; |
7073b16f | 106 | if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus))) |
cb1b69b0 | 107 | goto nla_put_failure; |
7073b16f | 108 | if (nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed))) |
cb1b69b0 | 109 | goto nla_put_failure; |
70ca767e LGL |
110 | if (priv->offset != 0) |
111 | if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset))) | |
112 | goto nla_put_failure; | |
cb1b69b0 LGL |
113 | return 0; |
114 | ||
115 | nla_put_failure: | |
116 | return -1; | |
117 | } | |
118 | ||
119 | static struct nft_expr_type nft_hash_type; | |
120 | static const struct nft_expr_ops nft_hash_ops = { | |
121 | .type = &nft_hash_type, | |
122 | .size = NFT_EXPR_SIZE(sizeof(struct nft_hash)), | |
123 | .eval = nft_hash_eval, | |
124 | .init = nft_hash_init, | |
125 | .dump = nft_hash_dump, | |
126 | }; | |
127 | ||
128 | static struct nft_expr_type nft_hash_type __read_mostly = { | |
129 | .name = "hash", | |
130 | .ops = &nft_hash_ops, | |
131 | .policy = nft_hash_policy, | |
132 | .maxattr = NFTA_HASH_MAX, | |
133 | .owner = THIS_MODULE, | |
134 | }; | |
135 | ||
136 | static int __init nft_hash_module_init(void) | |
137 | { | |
138 | return nft_register_expr(&nft_hash_type); | |
139 | } | |
140 | ||
141 | static void __exit nft_hash_module_exit(void) | |
142 | { | |
143 | nft_unregister_expr(&nft_hash_type); | |
144 | } | |
145 | ||
146 | module_init(nft_hash_module_init); | |
147 | module_exit(nft_hash_module_exit); | |
148 | ||
149 | MODULE_LICENSE("GPL"); | |
150 | MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); | |
151 | MODULE_ALIAS_NFT_EXPR("hash"); |