1 /*
2 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
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 * Development of this code funded by Astaro AG (http://www.astaro.com/)
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/netlink.h>
15 #include <linux/netfilter.h>
16 #include <linux/netfilter/nf_tables.h>
17 #include <net/netfilter/nf_tables.h>
18 // FIXME:
19 #include <net/ipv6.h>
20
21 struct nft_exthdr {
22 u8 type;
23 u8 offset;
24 u8 len;
25 enum nft_registers dreg:8;
26 };
27
nft_exthdr_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)28 static void nft_exthdr_eval(const struct nft_expr *expr,
29 struct nft_regs *regs,
30 const struct nft_pktinfo *pkt)
31 {
32 struct nft_exthdr *priv = nft_expr_priv(expr);
33 u32 *dest = ®s->data[priv->dreg];
34 unsigned int offset = 0;
35 int err;
36
37 err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
38 if (err < 0)
39 goto err;
40 offset += priv->offset;
41
42 dest[priv->len / NFT_REG32_SIZE] = 0;
43 if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
44 goto err;
45 return;
46 err:
47 regs->verdict.code = NFT_BREAK;
48 }
49
50 static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
51 [NFTA_EXTHDR_DREG] = { .type = NLA_U32 },
52 [NFTA_EXTHDR_TYPE] = { .type = NLA_U8 },
53 [NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 },
54 [NFTA_EXTHDR_LEN] = { .type = NLA_U32 },
55 };
56
nft_exthdr_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])57 static int nft_exthdr_init(const struct nft_ctx *ctx,
58 const struct nft_expr *expr,
59 const struct nlattr * const tb[])
60 {
61 struct nft_exthdr *priv = nft_expr_priv(expr);
62 u32 offset, len;
63 int err;
64
65 if (tb[NFTA_EXTHDR_DREG] == NULL ||
66 tb[NFTA_EXTHDR_TYPE] == NULL ||
67 tb[NFTA_EXTHDR_OFFSET] == NULL ||
68 tb[NFTA_EXTHDR_LEN] == NULL)
69 return -EINVAL;
70
71 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
72 if (err < 0)
73 return err;
74
75 err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
76 if (err < 0)
77 return err;
78
79 priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
80 priv->offset = offset;
81 priv->len = len;
82 priv->dreg = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
83
84 return nft_validate_register_store(ctx, priv->dreg, NULL,
85 NFT_DATA_VALUE, priv->len);
86 }
87
nft_exthdr_dump(struct sk_buff * skb,const struct nft_expr * expr)88 static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
89 {
90 const struct nft_exthdr *priv = nft_expr_priv(expr);
91
92 if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
93 goto nla_put_failure;
94 if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
95 goto nla_put_failure;
96 if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
97 goto nla_put_failure;
98 if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
99 goto nla_put_failure;
100 return 0;
101
102 nla_put_failure:
103 return -1;
104 }
105
106 static struct nft_expr_type nft_exthdr_type;
107 static const struct nft_expr_ops nft_exthdr_ops = {
108 .type = &nft_exthdr_type,
109 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
110 .eval = nft_exthdr_eval,
111 .init = nft_exthdr_init,
112 .dump = nft_exthdr_dump,
113 };
114
115 static struct nft_expr_type nft_exthdr_type __read_mostly = {
116 .name = "exthdr",
117 .ops = &nft_exthdr_ops,
118 .policy = nft_exthdr_policy,
119 .maxattr = NFTA_EXTHDR_MAX,
120 .owner = THIS_MODULE,
121 };
122
nft_exthdr_module_init(void)123 static int __init nft_exthdr_module_init(void)
124 {
125 return nft_register_expr(&nft_exthdr_type);
126 }
127
nft_exthdr_module_exit(void)128 static void __exit nft_exthdr_module_exit(void)
129 {
130 nft_unregister_expr(&nft_exthdr_type);
131 }
132
133 module_init(nft_exthdr_module_init);
134 module_exit(nft_exthdr_module_exit);
135
136 MODULE_LICENSE("GPL");
137 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
138 MODULE_ALIAS_NFT_EXPR("exthdr");
139