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 = &regs->data[priv->sreg];
32 u32 h;
33
34 h = reciprocal_scale(val: jhash(key: data, length: priv->len, initval: priv->seed),
35 ep_ro: 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(val: __skb_get_hash_symmetric_net(net: nft_net(pkt), skb),
55 ep_ro: priv->modulus);
56
57 regs->data[priv->dreg] = h + priv->offset;
58}
59
60static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
61 [NFTA_HASH_SREG] = { .type = NLA_U32 },
62 [NFTA_HASH_DREG] = { .type = NLA_U32 },
63 [NFTA_HASH_LEN] = NLA_POLICY_MAX(NLA_BE32, 255),
64 [NFTA_HASH_MODULUS] = { .type = NLA_U32 },
65 [NFTA_HASH_SEED] = { .type = NLA_U32 },
66 [NFTA_HASH_OFFSET] = { .type = NLA_U32 },
67 [NFTA_HASH_TYPE] = { .type = NLA_U32 },
68};
69
70static int nft_jhash_init(const struct nft_ctx *ctx,
71 const struct nft_expr *expr,
72 const struct nlattr * const tb[])
73{
74 struct nft_jhash *priv = nft_expr_priv(expr);
75 u32 len;
76 int err;
77
78 if (!tb[NFTA_HASH_SREG] ||
79 !tb[NFTA_HASH_DREG] ||
80 !tb[NFTA_HASH_LEN] ||
81 !tb[NFTA_HASH_MODULUS])
82 return -EINVAL;
83
84 if (tb[NFTA_HASH_OFFSET])
85 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
86
87 err = nft_parse_u32_check(attr: tb[NFTA_HASH_LEN], U8_MAX, dest: &len);
88 if (err < 0)
89 return err;
90 if (len == 0)
91 return -ERANGE;
92
93 priv->len = len;
94
95 err = nft_parse_register_load(ctx, attr: tb[NFTA_HASH_SREG], sreg: &priv->sreg, len);
96 if (err < 0)
97 return err;
98
99 priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
100 if (priv->modulus < 1)
101 return -ERANGE;
102
103 if (priv->offset + priv->modulus - 1 < priv->offset)
104 return -EOVERFLOW;
105
106 if (tb[NFTA_HASH_SEED]) {
107 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
108 } else {
109 priv->autogen_seed = true;
110 get_random_bytes(buf: &priv->seed, len: sizeof(priv->seed));
111 }
112
113 return nft_parse_register_store(ctx, attr: tb[NFTA_HASH_DREG], dreg: &priv->dreg,
114 NULL, type: NFT_DATA_VALUE, len: sizeof(u32));
115}
116
117static int nft_symhash_init(const struct nft_ctx *ctx,
118 const struct nft_expr *expr,
119 const struct nlattr * const tb[])
120{
121 struct nft_symhash *priv = nft_expr_priv(expr);
122
123 if (!tb[NFTA_HASH_DREG] ||
124 !tb[NFTA_HASH_MODULUS])
125 return -EINVAL;
126
127 if (tb[NFTA_HASH_OFFSET])
128 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
129
130 priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
131 if (priv->modulus < 1)
132 return -ERANGE;
133
134 if (priv->offset + priv->modulus - 1 < priv->offset)
135 return -EOVERFLOW;
136
137 return nft_parse_register_store(ctx, attr: tb[NFTA_HASH_DREG],
138 dreg: &priv->dreg, NULL, type: NFT_DATA_VALUE,
139 len: sizeof(u32));
140}
141
142static int nft_jhash_dump(struct sk_buff *skb,
143 const struct nft_expr *expr, bool reset)
144{
145 const struct nft_jhash *priv = nft_expr_priv(expr);
146
147 if (nft_dump_register(skb, attr: NFTA_HASH_SREG, reg: priv->sreg))
148 goto nla_put_failure;
149 if (nft_dump_register(skb, attr: NFTA_HASH_DREG, reg: priv->dreg))
150 goto nla_put_failure;
151 if (nla_put_be32(skb, attrtype: NFTA_HASH_LEN, htonl(priv->len)))
152 goto nla_put_failure;
153 if (nla_put_be32(skb, attrtype: NFTA_HASH_MODULUS, htonl(priv->modulus)))
154 goto nla_put_failure;
155 if (!priv->autogen_seed &&
156 nla_put_be32(skb, attrtype: NFTA_HASH_SEED, htonl(priv->seed)))
157 goto nla_put_failure;
158 if (priv->offset != 0)
159 if (nla_put_be32(skb, attrtype: NFTA_HASH_OFFSET, htonl(priv->offset)))
160 goto nla_put_failure;
161 if (nla_put_be32(skb, attrtype: NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS)))
162 goto nla_put_failure;
163 return 0;
164
165nla_put_failure:
166 return -1;
167}
168
169static bool nft_jhash_reduce(struct nft_regs_track *track,
170 const struct nft_expr *expr)
171{
172 const struct nft_jhash *priv = nft_expr_priv(expr);
173
174 nft_reg_track_cancel(track, dreg: priv->dreg, len: sizeof(u32));
175
176 return false;
177}
178
179static int nft_symhash_dump(struct sk_buff *skb,
180 const struct nft_expr *expr, bool reset)
181{
182 const struct nft_symhash *priv = nft_expr_priv(expr);
183
184 if (nft_dump_register(skb, attr: NFTA_HASH_DREG, reg: priv->dreg))
185 goto nla_put_failure;
186 if (nla_put_be32(skb, attrtype: NFTA_HASH_MODULUS, htonl(priv->modulus)))
187 goto nla_put_failure;
188 if (priv->offset != 0)
189 if (nla_put_be32(skb, attrtype: NFTA_HASH_OFFSET, htonl(priv->offset)))
190 goto nla_put_failure;
191 if (nla_put_be32(skb, attrtype: NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
192 goto nla_put_failure;
193 return 0;
194
195nla_put_failure:
196 return -1;
197}
198
199static bool nft_symhash_reduce(struct nft_regs_track *track,
200 const struct nft_expr *expr)
201{
202 struct nft_symhash *priv = nft_expr_priv(expr);
203 struct nft_symhash *symhash;
204
205 if (!nft_reg_track_cmp(track, expr, dreg: priv->dreg)) {
206 nft_reg_track_update(track, expr, dreg: priv->dreg, len: sizeof(u32));
207 return false;
208 }
209
210 symhash = nft_expr_priv(expr: track->regs[priv->dreg].selector);
211 if (priv->offset != symhash->offset ||
212 priv->modulus != symhash->modulus) {
213 nft_reg_track_update(track, expr, dreg: priv->dreg, len: sizeof(u32));
214 return false;
215 }
216
217 if (!track->regs[priv->dreg].bitwise)
218 return true;
219
220 return false;
221}
222
223static struct nft_expr_type nft_hash_type;
224static const struct nft_expr_ops nft_jhash_ops = {
225 .type = &nft_hash_type,
226 .size = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
227 .eval = nft_jhash_eval,
228 .init = nft_jhash_init,
229 .dump = nft_jhash_dump,
230 .reduce = nft_jhash_reduce,
231};
232
233static const struct nft_expr_ops nft_symhash_ops = {
234 .type = &nft_hash_type,
235 .size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
236 .eval = nft_symhash_eval,
237 .init = nft_symhash_init,
238 .dump = nft_symhash_dump,
239 .reduce = nft_symhash_reduce,
240};
241
242static const struct nft_expr_ops *
243nft_hash_select_ops(const struct nft_ctx *ctx,
244 const struct nlattr * const tb[])
245{
246 u32 type;
247
248 if (!tb[NFTA_HASH_TYPE])
249 return &nft_jhash_ops;
250
251 type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
252 switch (type) {
253 case NFT_HASH_SYM:
254 return &nft_symhash_ops;
255 case NFT_HASH_JENKINS:
256 return &nft_jhash_ops;
257 default:
258 break;
259 }
260 return ERR_PTR(error: -EOPNOTSUPP);
261}
262
263static struct nft_expr_type nft_hash_type __read_mostly = {
264 .name = "hash",
265 .select_ops = nft_hash_select_ops,
266 .policy = nft_hash_policy,
267 .maxattr = NFTA_HASH_MAX,
268 .owner = THIS_MODULE,
269};
270
271static int __init nft_hash_module_init(void)
272{
273 return nft_register_expr(&nft_hash_type);
274}
275
276static void __exit nft_hash_module_exit(void)
277{
278 nft_unregister_expr(&nft_hash_type);
279}
280
281module_init(nft_hash_module_init);
282module_exit(nft_hash_module_exit);
283
284MODULE_LICENSE("GPL");
285MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
286MODULE_ALIAS_NFT_EXPR("hash");
287MODULE_DESCRIPTION("Netfilter nftables hash module");
288

source code of linux/net/netfilter/nft_hash.c