summaryrefslogtreecommitdiff
path: root/net/netfilter/nft_payload.c
blob: 09b4b07eb67644fdc90ef357378c46d243b7a642 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
/*
 * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/kernel.h>
#include <linux/if_vlan.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>

/* add vlan header into the user buffer for if tag was removed by offloads */
static bool
nft_payload_copy_vlan(u32 *d, const struct sk_buff *skb, u8 offset, u8 len)
{
	int mac_off = skb_mac_header(skb) - skb->data;
	u8 vlan_len, *vlanh, *dst_u8 = (u8 *) d;
	struct vlan_ethhdr veth;

	vlanh = (u8 *) &veth;
	if (offset < ETH_HLEN) {
		u8 ethlen = min_t(u8, len, ETH_HLEN - offset);

		if (skb_copy_bits(skb, mac_off, &veth, ETH_HLEN))
			return false;

		veth.h_vlan_proto = skb->vlan_proto;

		memcpy(dst_u8, vlanh + offset, ethlen);

		len -= ethlen;
		if (len == 0)
			return true;

		dst_u8 += ethlen;
		offset = ETH_HLEN;
	} else if (offset >= VLAN_ETH_HLEN) {
		offset -= VLAN_HLEN;
		goto skip;
	}

	veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
	veth.h_vlan_encapsulated_proto = skb->protocol;

	vlanh += offset;

	vlan_len = min_t(u8, len, VLAN_ETH_HLEN - offset);
	memcpy(dst_u8, vlanh, vlan_len);

	len -= vlan_len;
	if (!len)
		return true;

	dst_u8 += vlan_len;
 skip:
	return skb_copy_bits(skb, offset + mac_off, dst_u8, len) == 0;
}

static void nft_payload_eval(const struct nft_expr *expr,
			     struct nft_regs *regs,
			     const struct nft_pktinfo *pkt)
{
	const struct nft_payload *priv = nft_expr_priv(expr);
	const struct sk_buff *skb = pkt->skb;
	u32 *dest = &regs->data[priv->dreg];
	int offset;

	dest[priv->len / NFT_REG32_SIZE] = 0;
	switch (priv->base) {
	case NFT_PAYLOAD_LL_HEADER:
		if (!skb_mac_header_was_set(skb))
			goto err;

		if (skb_vlan_tag_present(skb)) {
			if (!nft_payload_copy_vlan(dest, skb,
						   priv->offset, priv->len))
				goto err;
			return;
		}
		offset = skb_mac_header(skb) - skb->data;
		break;
	case NFT_PAYLOAD_NETWORK_HEADER:
		offset = skb_network_offset(skb);
		break;
	case NFT_PAYLOAD_TRANSPORT_HEADER:
		offset = pkt->xt.thoff;
		break;
	default:
		BUG();
	}
	offset += priv->offset;

	if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
		goto err;
	return;
err:
	regs->verdict.code = NFT_BREAK;
}

static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
	[NFTA_PAYLOAD_DREG]	= { .type = NLA_U32 },
	[NFTA_PAYLOAD_BASE]	= { .type = NLA_U32 },
	[NFTA_PAYLOAD_OFFSET]	= { .type = NLA_U32 },
	[NFTA_PAYLOAD_LEN]	= { .type = NLA_U32 },
};

static int nft_payload_init(const struct nft_ctx *ctx,
			    const struct nft_expr *expr,
			    const struct nlattr * const tb[])
{
	struct nft_payload *priv = nft_expr_priv(expr);

	priv->base   = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
	priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
	priv->len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
	priv->dreg   = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);

	return nft_validate_register_store(ctx, priv->dreg, NULL,
					   NFT_DATA_VALUE, priv->len);
}

static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
	const struct nft_payload *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) ||
	    nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
	    nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
	    nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -1;
}

static struct nft_expr_type nft_payload_type;
static const struct nft_expr_ops nft_payload_ops = {
	.type		= &nft_payload_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_payload)),
	.eval		= nft_payload_eval,
	.init		= nft_payload_init,
	.dump		= nft_payload_dump,
};

const struct nft_expr_ops nft_payload_fast_ops = {
	.type		= &nft_payload_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_payload)),
	.eval		= nft_payload_eval,
	.init		= nft_payload_init,
	.dump		= nft_payload_dump,
};

static const struct nft_expr_ops *
nft_payload_select_ops(const struct nft_ctx *ctx,
		       const struct nlattr * const tb[])
{
	enum nft_payload_bases base;
	unsigned int offset, len;

	if (tb[NFTA_PAYLOAD_DREG] == NULL ||
	    tb[NFTA_PAYLOAD_BASE] == NULL ||
	    tb[NFTA_PAYLOAD_OFFSET] == NULL ||
	    tb[NFTA_PAYLOAD_LEN] == NULL)
		return ERR_PTR(-EINVAL);

	base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
	switch (base) {
	case NFT_PAYLOAD_LL_HEADER:
	case NFT_PAYLOAD_NETWORK_HEADER:
	case NFT_PAYLOAD_TRANSPORT_HEADER:
		break;
	default:
		return ERR_PTR(-EOPNOTSUPP);
	}

	offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
	len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));

	if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
	    base != NFT_PAYLOAD_LL_HEADER)
		return &nft_payload_fast_ops;
	else
		return &nft_payload_ops;
}

static struct nft_expr_type nft_payload_type __read_mostly = {
	.name		= "payload",
	.select_ops	= nft_payload_select_ops,
	.policy		= nft_payload_policy,
	.maxattr	= NFTA_PAYLOAD_MAX,
	.owner		= THIS_MODULE,
};

int __init nft_payload_module_init(void)
{
	return nft_register_expr(&nft_payload_type);
}

void nft_payload_module_exit(void)
{
	nft_unregister_expr(&nft_payload_type);
}