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 u8 sreg;
18 u8 dreg;
19 u8 len;
20 bool autogen_seed:1;
21 u32 modulus;
22 u32 seed;
23 u32 offset;
24 };
25
nft_jhash_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)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 = ®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
40 struct nft_symhash {
41 u8 dreg;
42 u32 modulus;
43 u32 offset;
44 };
45
nft_symhash_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)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
nft_jhash_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])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 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
nft_symhash_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])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->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
nft_jhash_dump(struct sk_buff * skb,const struct nft_expr * expr)141 static 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
164 nla_put_failure:
165 return -1;
166 }
167
nft_jhash_reduce(struct nft_regs_track * track,const struct nft_expr * expr)168 static bool nft_jhash_reduce(struct nft_regs_track *track,
169 const struct nft_expr *expr)
170 {
171 const struct nft_jhash *priv = nft_expr_priv(expr);
172
173 nft_reg_track_cancel(track, priv->dreg, sizeof(u32));
174
175 return false;
176 }
177
nft_symhash_dump(struct sk_buff * skb,const struct nft_expr * expr)178 static int nft_symhash_dump(struct sk_buff *skb,
179 const struct nft_expr *expr)
180 {
181 const struct nft_symhash *priv = nft_expr_priv(expr);
182
183 if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
184 goto nla_put_failure;
185 if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
186 goto nla_put_failure;
187 if (priv->offset != 0)
188 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
189 goto nla_put_failure;
190 if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
191 goto nla_put_failure;
192 return 0;
193
194 nla_put_failure:
195 return -1;
196 }
197
nft_symhash_reduce(struct nft_regs_track * track,const struct nft_expr * expr)198 static bool nft_symhash_reduce(struct nft_regs_track *track,
199 const struct nft_expr *expr)
200 {
201 struct nft_symhash *priv = nft_expr_priv(expr);
202 struct nft_symhash *symhash;
203
204 if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
205 nft_reg_track_update(track, expr, priv->dreg, sizeof(u32));
206 return false;
207 }
208
209 symhash = nft_expr_priv(track->regs[priv->dreg].selector);
210 if (priv->offset != symhash->offset ||
211 priv->modulus != symhash->modulus) {
212 nft_reg_track_update(track, expr, priv->dreg, sizeof(u32));
213 return false;
214 }
215
216 if (!track->regs[priv->dreg].bitwise)
217 return true;
218
219 return false;
220 }
221
222 static struct nft_expr_type nft_hash_type;
223 static const struct nft_expr_ops nft_jhash_ops = {
224 .type = &nft_hash_type,
225 .size = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
226 .eval = nft_jhash_eval,
227 .init = nft_jhash_init,
228 .dump = nft_jhash_dump,
229 .reduce = nft_jhash_reduce,
230 };
231
232 static const struct nft_expr_ops nft_symhash_ops = {
233 .type = &nft_hash_type,
234 .size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
235 .eval = nft_symhash_eval,
236 .init = nft_symhash_init,
237 .dump = nft_symhash_dump,
238 .reduce = nft_symhash_reduce,
239 };
240
241 static const struct nft_expr_ops *
nft_hash_select_ops(const struct nft_ctx * ctx,const struct nlattr * const tb[])242 nft_hash_select_ops(const struct nft_ctx *ctx,
243 const struct nlattr * const tb[])
244 {
245 u32 type;
246
247 if (!tb[NFTA_HASH_TYPE])
248 return &nft_jhash_ops;
249
250 type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
251 switch (type) {
252 case NFT_HASH_SYM:
253 return &nft_symhash_ops;
254 case NFT_HASH_JENKINS:
255 return &nft_jhash_ops;
256 default:
257 break;
258 }
259 return ERR_PTR(-EOPNOTSUPP);
260 }
261
262 static struct nft_expr_type nft_hash_type __read_mostly = {
263 .name = "hash",
264 .select_ops = nft_hash_select_ops,
265 .policy = nft_hash_policy,
266 .maxattr = NFTA_HASH_MAX,
267 .owner = THIS_MODULE,
268 };
269
nft_hash_module_init(void)270 static int __init nft_hash_module_init(void)
271 {
272 return nft_register_expr(&nft_hash_type);
273 }
274
nft_hash_module_exit(void)275 static void __exit nft_hash_module_exit(void)
276 {
277 nft_unregister_expr(&nft_hash_type);
278 }
279
280 module_init(nft_hash_module_init);
281 module_exit(nft_hash_module_exit);
282
283 MODULE_LICENSE("GPL");
284 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
285 MODULE_ALIAS_NFT_EXPR("hash");
286 MODULE_DESCRIPTION("Netfilter nftables hash module");
287
