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_regs * regs,const struct nft_pktinfo * pkt)20 static void nft_payload_eval(const struct nft_expr *expr,
21 struct nft_regs *regs,
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 u32 *dest = ®s->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 dest[priv->len / NFT_REG32_SIZE] = 0;
47 if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
48 goto err;
49 return;
50 err:
51 regs->verdict.code = NFT_BREAK;
52 }
53
54 static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
55 [NFTA_PAYLOAD_DREG] = { .type = NLA_U32 },
56 [NFTA_PAYLOAD_BASE] = { .type = NLA_U32 },
57 [NFTA_PAYLOAD_OFFSET] = { .type = NLA_U32 },
58 [NFTA_PAYLOAD_LEN] = { .type = NLA_U32 },
59 };
60
nft_payload_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])61 static int nft_payload_init(const struct nft_ctx *ctx,
62 const struct nft_expr *expr,
63 const struct nlattr * const tb[])
64 {
65 struct nft_payload *priv = nft_expr_priv(expr);
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 priv->dreg = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);
71
72 return nft_validate_register_store(ctx, priv->dreg, NULL,
73 NFT_DATA_VALUE, priv->len);
74 }
75
nft_payload_dump(struct sk_buff * skb,const struct nft_expr * expr)76 static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr)
77 {
78 const struct nft_payload *priv = nft_expr_priv(expr);
79
80 if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) ||
81 nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
82 nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
83 nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
84 goto nla_put_failure;
85 return 0;
86
87 nla_put_failure:
88 return -1;
89 }
90
91 static struct nft_expr_type nft_payload_type;
92 static const struct nft_expr_ops nft_payload_ops = {
93 .type = &nft_payload_type,
94 .size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
95 .eval = nft_payload_eval,
96 .init = nft_payload_init,
97 .dump = nft_payload_dump,
98 };
99
100 const struct nft_expr_ops nft_payload_fast_ops = {
101 .type = &nft_payload_type,
102 .size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
103 .eval = nft_payload_eval,
104 .init = nft_payload_init,
105 .dump = nft_payload_dump,
106 };
107
108 static const struct nft_expr_ops *
nft_payload_select_ops(const struct nft_ctx * ctx,const struct nlattr * const tb[])109 nft_payload_select_ops(const struct nft_ctx *ctx,
110 const struct nlattr * const tb[])
111 {
112 enum nft_payload_bases base;
113 unsigned int offset, len;
114
115 if (tb[NFTA_PAYLOAD_DREG] == NULL ||
116 tb[NFTA_PAYLOAD_BASE] == NULL ||
117 tb[NFTA_PAYLOAD_OFFSET] == NULL ||
118 tb[NFTA_PAYLOAD_LEN] == NULL)
119 return ERR_PTR(-EINVAL);
120
121 base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
122 switch (base) {
123 case NFT_PAYLOAD_LL_HEADER:
124 case NFT_PAYLOAD_NETWORK_HEADER:
125 case NFT_PAYLOAD_TRANSPORT_HEADER:
126 break;
127 default:
128 return ERR_PTR(-EOPNOTSUPP);
129 }
130
131 offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
132 len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
133
134 if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
135 base != NFT_PAYLOAD_LL_HEADER)
136 return &nft_payload_fast_ops;
137 else
138 return &nft_payload_ops;
139 }
140
141 static struct nft_expr_type nft_payload_type __read_mostly = {
142 .name = "payload",
143 .select_ops = nft_payload_select_ops,
144 .policy = nft_payload_policy,
145 .maxattr = NFTA_PAYLOAD_MAX,
146 .owner = THIS_MODULE,
147 };
148
nft_payload_module_init(void)149 int __init nft_payload_module_init(void)
150 {
151 return nft_register_expr(&nft_payload_type);
152 }
153
nft_payload_module_exit(void)154 void nft_payload_module_exit(void)
155 {
156 nft_unregister_expr(&nft_payload_type);
157 }
158