1 /*
2 * Copyright (c) 2008-2009 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
nft_payload_eval(const struct nft_expr * expr,struct nft_data data[NFT_REG_MAX+1],const struct nft_pktinfo * pkt)20 static void nft_payload_eval(const struct nft_expr *expr,
21 struct nft_data data[NFT_REG_MAX + 1],
22 const struct nft_pktinfo *pkt)
23 {
24 const struct nft_payload *priv = nft_expr_priv(expr);
25 const struct sk_buff *skb = pkt->skb;
26 struct nft_data *dest = &data[priv->dreg];
27 int offset;
28
29 switch (priv->base) {
30 case NFT_PAYLOAD_LL_HEADER:
31 if (!skb_mac_header_was_set(skb))
32 goto err;
33 offset = skb_mac_header(skb) - skb->data;
34 break;
35 case NFT_PAYLOAD_NETWORK_HEADER:
36 offset = skb_network_offset(skb);
37 break;
38 case NFT_PAYLOAD_TRANSPORT_HEADER:
39 offset = pkt->xt.thoff;
40 break;
41 default:
42 BUG();
43 }
44 offset += priv->offset;
45
46 if (skb_copy_bits(skb, offset, dest->data, priv->len) < 0)
47 goto err;
48 return;
49 err:
50 data[NFT_REG_VERDICT].verdict = NFT_BREAK;
51 }
52
53 static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
54 [NFTA_PAYLOAD_DREG] = { .type = NLA_U32 },
55 [NFTA_PAYLOAD_BASE] = { .type = NLA_U32 },
56 [NFTA_PAYLOAD_OFFSET] = { .type = NLA_U32 },
57 [NFTA_PAYLOAD_LEN] = { .type = NLA_U32 },
58 };
59
nft_payload_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])60 static int nft_payload_init(const struct nft_ctx *ctx,
61 const struct nft_expr *expr,
62 const struct nlattr * const tb[])
63 {
64 struct nft_payload *priv = nft_expr_priv(expr);
65 int err;
66
67 priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
68 priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
69 priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
70
71 priv->dreg = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_DREG]));
72 err = nft_validate_output_register(priv->dreg);
73 if (err < 0)
74 return err;
75 return nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE);
76 }
77
nft_payload_dump(struct sk_buff * skb,const struct nft_expr * expr)78 static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr)
79 {
80 const struct nft_payload *priv = nft_expr_priv(expr);
81
82 if (nla_put_be32(skb, NFTA_PAYLOAD_DREG, htonl(priv->dreg)) ||
83 nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
84 nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
85 nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
86 goto nla_put_failure;
87 return 0;
88
89 nla_put_failure:
90 return -1;
91 }
92
93 static struct nft_expr_type nft_payload_type;
94 static const struct nft_expr_ops nft_payload_ops = {
95 .type = &nft_payload_type,
96 .size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
97 .eval = nft_payload_eval,
98 .init = nft_payload_init,
99 .dump = nft_payload_dump,
100 };
101
102 const struct nft_expr_ops nft_payload_fast_ops = {
103 .type = &nft_payload_type,
104 .size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
105 .eval = nft_payload_eval,
106 .init = nft_payload_init,
107 .dump = nft_payload_dump,
108 };
109
110 static const struct nft_expr_ops *
nft_payload_select_ops(const struct nft_ctx * ctx,const struct nlattr * const tb[])111 nft_payload_select_ops(const struct nft_ctx *ctx,
112 const struct nlattr * const tb[])
113 {
114 enum nft_payload_bases base;
115 unsigned int offset, len;
116
117 if (tb[NFTA_PAYLOAD_DREG] == NULL ||
118 tb[NFTA_PAYLOAD_BASE] == NULL ||
119 tb[NFTA_PAYLOAD_OFFSET] == NULL ||
120 tb[NFTA_PAYLOAD_LEN] == NULL)
121 return ERR_PTR(-EINVAL);
122
123 base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
124 switch (base) {
125 case NFT_PAYLOAD_LL_HEADER:
126 case NFT_PAYLOAD_NETWORK_HEADER:
127 case NFT_PAYLOAD_TRANSPORT_HEADER:
128 break;
129 default:
130 return ERR_PTR(-EOPNOTSUPP);
131 }
132
133 offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
134 len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
135 if (len == 0 || len > FIELD_SIZEOF(struct nft_data, data))
136 return ERR_PTR(-EINVAL);
137
138 if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
139 base != NFT_PAYLOAD_LL_HEADER)
140 return &nft_payload_fast_ops;
141 else
142 return &nft_payload_ops;
143 }
144
145 static struct nft_expr_type nft_payload_type __read_mostly = {
146 .name = "payload",
147 .select_ops = nft_payload_select_ops,
148 .policy = nft_payload_policy,
149 .maxattr = NFTA_PAYLOAD_MAX,
150 .owner = THIS_MODULE,
151 };
152
nft_payload_module_init(void)153 int __init nft_payload_module_init(void)
154 {
155 return nft_register_expr(&nft_payload_type);
156 }
157
nft_payload_module_exit(void)158 void nft_payload_module_exit(void)
159 {
160 nft_unregister_expr(&nft_payload_type);
161 }
162