2 * Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
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.
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>
21 enum nft_registers sreg
:8;
22 enum nft_registers dreg
:8;
30 static void nft_hash_eval(const struct nft_expr
*expr
,
31 struct nft_regs
*regs
,
32 const struct nft_pktinfo
*pkt
)
34 struct nft_hash
*priv
= nft_expr_priv(expr
);
35 const void *data
= ®s
->data
[priv
->sreg
];
38 h
= reciprocal_scale(jhash(data
, priv
->len
, priv
->seed
), priv
->modulus
);
39 regs
->data
[priv
->dreg
] = h
+ priv
->offset
;
42 static const struct nla_policy nft_hash_policy
[NFTA_HASH_MAX
+ 1] = {
43 [NFTA_HASH_SREG
] = { .type
= NLA_U32
},
44 [NFTA_HASH_DREG
] = { .type
= NLA_U32
},
45 [NFTA_HASH_LEN
] = { .type
= NLA_U32
},
46 [NFTA_HASH_MODULUS
] = { .type
= NLA_U32
},
47 [NFTA_HASH_SEED
] = { .type
= NLA_U32
},
48 [NFTA_HASH_OFFSET
] = { .type
= NLA_U32
},
51 static int nft_hash_init(const struct nft_ctx
*ctx
,
52 const struct nft_expr
*expr
,
53 const struct nlattr
* const tb
[])
55 struct nft_hash
*priv
= nft_expr_priv(expr
);
59 if (!tb
[NFTA_HASH_SREG
] ||
60 !tb
[NFTA_HASH_DREG
] ||
62 !tb
[NFTA_HASH_MODULUS
])
65 if (tb
[NFTA_HASH_OFFSET
])
66 priv
->offset
= ntohl(nla_get_be32(tb
[NFTA_HASH_OFFSET
]));
68 priv
->sreg
= nft_parse_register(tb
[NFTA_HASH_SREG
]);
69 priv
->dreg
= nft_parse_register(tb
[NFTA_HASH_DREG
]);
71 err
= nft_parse_u32_check(tb
[NFTA_HASH_LEN
], U8_MAX
, &len
);
79 priv
->modulus
= ntohl(nla_get_be32(tb
[NFTA_HASH_MODULUS
]));
80 if (priv
->modulus
<= 1)
83 if (priv
->offset
+ priv
->modulus
- 1 < priv
->offset
)
86 if (tb
[NFTA_HASH_SEED
]) {
87 priv
->seed
= ntohl(nla_get_be32(tb
[NFTA_HASH_SEED
]));
89 priv
->autogen_seed
= true;
90 get_random_bytes(&priv
->seed
, sizeof(priv
->seed
));
93 return nft_validate_register_load(priv
->sreg
, len
) &&
94 nft_validate_register_store(ctx
, priv
->dreg
, NULL
,
95 NFT_DATA_VALUE
, sizeof(u32
));
98 static int nft_hash_dump(struct sk_buff
*skb
,
99 const struct nft_expr
*expr
)
101 const struct nft_hash
*priv
= nft_expr_priv(expr
);
103 if (nft_dump_register(skb
, NFTA_HASH_SREG
, priv
->sreg
))
104 goto nla_put_failure
;
105 if (nft_dump_register(skb
, NFTA_HASH_DREG
, priv
->dreg
))
106 goto nla_put_failure
;
107 if (nla_put_be32(skb
, NFTA_HASH_LEN
, htonl(priv
->len
)))
108 goto nla_put_failure
;
109 if (nla_put_be32(skb
, NFTA_HASH_MODULUS
, htonl(priv
->modulus
)))
110 goto nla_put_failure
;
111 if (!priv
->autogen_seed
&&
112 nla_put_be32(skb
, NFTA_HASH_SEED
, htonl(priv
->seed
)))
113 goto nla_put_failure
;
114 if (priv
->offset
!= 0)
115 if (nla_put_be32(skb
, NFTA_HASH_OFFSET
, htonl(priv
->offset
)))
116 goto nla_put_failure
;
123 static struct nft_expr_type nft_hash_type
;
124 static const struct nft_expr_ops nft_hash_ops
= {
125 .type
= &nft_hash_type
,
126 .size
= NFT_EXPR_SIZE(sizeof(struct nft_hash
)),
127 .eval
= nft_hash_eval
,
128 .init
= nft_hash_init
,
129 .dump
= nft_hash_dump
,
132 static struct nft_expr_type nft_hash_type __read_mostly
= {
134 .ops
= &nft_hash_ops
,
135 .policy
= nft_hash_policy
,
136 .maxattr
= NFTA_HASH_MAX
,
137 .owner
= THIS_MODULE
,
140 static int __init
nft_hash_module_init(void)
142 return nft_register_expr(&nft_hash_type
);
145 static void __exit
nft_hash_module_exit(void)
147 nft_unregister_expr(&nft_hash_type
);
150 module_init(nft_hash_module_init
);
151 module_exit(nft_hash_module_exit
);
153 MODULE_LICENSE("GPL");
154 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
155 MODULE_ALIAS_NFT_EXPR("hash");