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96518518 PM |
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_core.h> | |
18 | #include <net/netfilter/nf_tables.h> | |
19 | ||
20 | struct nft_payload { | |
21 | enum nft_payload_bases base:8; | |
22 | u8 offset; | |
23 | u8 len; | |
24 | enum nft_registers dreg:8; | |
25 | }; | |
26 | ||
27 | static void nft_payload_eval(const struct nft_expr *expr, | |
28 | struct nft_data data[NFT_REG_MAX + 1], | |
29 | const struct nft_pktinfo *pkt) | |
30 | { | |
31 | const struct nft_payload *priv = nft_expr_priv(expr); | |
32 | const struct sk_buff *skb = pkt->skb; | |
33 | struct nft_data *dest = &data[priv->dreg]; | |
34 | int offset; | |
35 | ||
36 | switch (priv->base) { | |
37 | case NFT_PAYLOAD_LL_HEADER: | |
38 | if (!skb_mac_header_was_set(skb)) | |
39 | goto err; | |
40 | offset = skb_mac_header(skb) - skb->data; | |
41 | break; | |
42 | case NFT_PAYLOAD_NETWORK_HEADER: | |
43 | offset = skb_network_offset(skb); | |
44 | break; | |
45 | case NFT_PAYLOAD_TRANSPORT_HEADER: | |
46 | offset = skb_transport_offset(skb); | |
47 | break; | |
48 | default: | |
49 | BUG(); | |
50 | } | |
51 | offset += priv->offset; | |
52 | ||
53 | if (skb_copy_bits(skb, offset, dest->data, priv->len) < 0) | |
54 | goto err; | |
55 | return; | |
56 | err: | |
57 | data[NFT_REG_VERDICT].verdict = NFT_BREAK; | |
58 | } | |
59 | ||
60 | static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = { | |
61 | [NFTA_PAYLOAD_DREG] = { .type = NLA_U32 }, | |
62 | [NFTA_PAYLOAD_BASE] = { .type = NLA_U32 }, | |
63 | [NFTA_PAYLOAD_OFFSET] = { .type = NLA_U32 }, | |
64 | [NFTA_PAYLOAD_LEN] = { .type = NLA_U32 }, | |
65 | }; | |
66 | ||
67 | static int nft_payload_init(const struct nft_ctx *ctx, | |
68 | const struct nft_expr *expr, | |
69 | const struct nlattr * const tb[]) | |
70 | { | |
71 | struct nft_payload *priv = nft_expr_priv(expr); | |
72 | int err; | |
73 | ||
74 | if (tb[NFTA_PAYLOAD_DREG] == NULL || | |
75 | tb[NFTA_PAYLOAD_BASE] == NULL || | |
76 | tb[NFTA_PAYLOAD_OFFSET] == NULL || | |
77 | tb[NFTA_PAYLOAD_LEN] == NULL) | |
78 | return -EINVAL; | |
79 | ||
80 | priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE])); | |
81 | switch (priv->base) { | |
82 | case NFT_PAYLOAD_LL_HEADER: | |
83 | case NFT_PAYLOAD_NETWORK_HEADER: | |
84 | case NFT_PAYLOAD_TRANSPORT_HEADER: | |
85 | break; | |
86 | default: | |
87 | return -EOPNOTSUPP; | |
88 | } | |
89 | ||
90 | priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET])); | |
91 | priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN])); | |
92 | if (priv->len == 0 || | |
93 | priv->len > FIELD_SIZEOF(struct nft_data, data)) | |
94 | return -EINVAL; | |
95 | ||
96 | priv->dreg = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_DREG])); | |
97 | err = nft_validate_output_register(priv->dreg); | |
98 | if (err < 0) | |
99 | return err; | |
100 | return nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE); | |
101 | } | |
102 | ||
103 | static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr) | |
104 | { | |
105 | const struct nft_payload *priv = nft_expr_priv(expr); | |
106 | ||
107 | if (nla_put_be32(skb, NFTA_PAYLOAD_DREG, htonl(priv->dreg)) || | |
108 | nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) || | |
109 | nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) || | |
110 | nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len))) | |
111 | goto nla_put_failure; | |
112 | return 0; | |
113 | ||
114 | nla_put_failure: | |
115 | return -1; | |
116 | } | |
117 | ||
118 | static struct nft_expr_ops nft_payload_ops __read_mostly = { | |
119 | .name = "payload", | |
120 | .size = NFT_EXPR_SIZE(sizeof(struct nft_payload)), | |
121 | .owner = THIS_MODULE, | |
122 | .eval = nft_payload_eval, | |
123 | .init = nft_payload_init, | |
124 | .dump = nft_payload_dump, | |
125 | .policy = nft_payload_policy, | |
126 | .maxattr = NFTA_PAYLOAD_MAX, | |
127 | }; | |
128 | ||
129 | int __init nft_payload_module_init(void) | |
130 | { | |
131 | return nft_register_expr(&nft_payload_ops); | |
132 | } | |
133 | ||
134 | void nft_payload_module_exit(void) | |
135 | { | |
136 | nft_unregister_expr(&nft_payload_ops); | |
137 | } |