aboutsummaryrefslogtreecommitdiff
path: root/net/ipv6/xfrm6_output.c
blob: 601a148f60f39af5255d651eab7a1f8d23a35a57 (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
/*
 * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
 * Copyright (C) 2002 USAGI/WIDE Project
 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/icmpv6.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <net/ipv6.h>
#include <net/xfrm.h>

/* Add encapsulation header.
 *
 * In transport mode, the IP header and mutable extension headers will be moved
 * forward to make space for the encapsulation header.
 *
 * In tunnel mode, the top IP header will be constructed per RFC 2401.
 * The following fields in it shall be filled in by x->type->output:
 *	payload_len
 *
 * On exit, skb->h will be set to the start of the encapsulation header to be
 * filled in by x->type->output and skb->nh will be set to the nextheader field
 * of the extension header directly preceding the encapsulation header, or in
 * its absence, that of the top IP header.  The value of skb->data will always
 * point to the top IP header.
 */
static void xfrm6_encap(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct xfrm_state *x = dst->xfrm;
	struct ipv6hdr *iph, *top_iph;
	int dsfield;

	skb_push(skb, x->props.header_len);
	iph = skb->nh.ipv6h;

	if (!x->props.mode) {
		u8 *prevhdr;
		int hdr_len;

		hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
		skb->nh.raw = prevhdr - x->props.header_len;
		skb->h.raw = skb->data + hdr_len;
		memmove(skb->data, iph, hdr_len);
		return;
	}

	skb->nh.raw = skb->data;
	top_iph = skb->nh.ipv6h;
	skb->nh.raw = &top_iph->nexthdr;
	skb->h.ipv6h = top_iph + 1;

	top_iph->version = 6;
	top_iph->priority = iph->priority;
	top_iph->flow_lbl[0] = iph->flow_lbl[0];
	top_iph->flow_lbl[1] = iph->flow_lbl[1];
	top_iph->flow_lbl[2] = iph->flow_lbl[2];
	dsfield = ipv6_get_dsfield(top_iph);
	dsfield = INET_ECN_encapsulate(dsfield, dsfield);
	if (x->props.flags & XFRM_STATE_NOECN)
		dsfield &= ~INET_ECN_MASK;
	ipv6_change_dsfield(top_iph, 0, dsfield);
	top_iph->nexthdr = IPPROTO_IPV6; 
	top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
	ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
	ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
}

static int xfrm6_tunnel_check_size(struct sk_buff *skb)
{
	int mtu, ret = 0;
	struct dst_entry *dst = skb->dst;

	mtu = dst_mtu(dst);
	if (mtu < IPV6_MIN_MTU)
		mtu = IPV6_MIN_MTU;

	if (skb->len > mtu) {
		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
		ret = -EMSGSIZE;
	}

	return ret;
}

int xfrm6_output(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct xfrm_state *x = dst->xfrm;
	int err;
	
	if (skb->ip_summed == CHECKSUM_HW) {
		err = skb_checksum_help(skb, 0);
		if (err)
			goto error_nolock;
	}

	if (x->props.mode) {
		err = xfrm6_tunnel_check_size(skb);
		if (err)
			goto error_nolock;
	}

	spin_lock_bh(&x->lock);
	err = xfrm_state_check(x, skb);
	if (err)
		goto error;

	xfrm6_encap(skb);

	err = x->type->output(x, skb);
	if (err)
		goto error;

	x->curlft.bytes += skb->len;
	x->curlft.packets++;

	spin_unlock_bh(&x->lock);

	skb->nh.raw = skb->data;
	
	if (!(skb->dst = dst_pop(dst))) {
		err = -EHOSTUNREACH;
		goto error_nolock;
	}
	err = NET_XMIT_BYPASS;

out_exit:
	return err;
error:
	spin_unlock_bh(&x->lock);
error_nolock:
	kfree_skb(skb);
	goto out_exit;
}