blob: 6b9867717d117a6686edb9424ddbfb6e7a21aa05 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
3 * Copyright (C) 2002 USAGI/WIDE Project
4 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/skbuff.h>
13#include <linux/spinlock.h>
14#include <linux/icmpv6.h>
15#include <net/dsfield.h>
16#include <net/inet_ecn.h>
17#include <net/ipv6.h>
18#include <net/xfrm.h>
19
20/* Add encapsulation header.
21 *
22 * In transport mode, the IP header and mutable extension headers will be moved
23 * forward to make space for the encapsulation header.
24 *
25 * In tunnel mode, the top IP header will be constructed per RFC 2401.
26 * The following fields in it shall be filled in by x->type->output:
27 * payload_len
28 *
29 * On exit, skb->h will be set to the start of the encapsulation header to be
30 * filled in by x->type->output and skb->nh will be set to the nextheader field
31 * of the extension header directly preceding the encapsulation header, or in
32 * its absence, that of the top IP header. The value of skb->data will always
33 * point to the top IP header.
34 */
35static void xfrm6_encap(struct sk_buff *skb)
36{
37 struct dst_entry *dst = skb->dst;
38 struct xfrm_state *x = dst->xfrm;
39 struct ipv6hdr *iph, *top_iph;
40 int dsfield;
41
42 skb_push(skb, x->props.header_len);
43 iph = skb->nh.ipv6h;
44
45 if (!x->props.mode) {
46 u8 *prevhdr;
47 int hdr_len;
48
49 hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
50 skb->nh.raw = prevhdr - x->props.header_len;
51 skb->h.raw = skb->data + hdr_len;
52 memmove(skb->data, iph, hdr_len);
53 return;
54 }
55
56 skb->nh.raw = skb->data;
57 top_iph = skb->nh.ipv6h;
58 skb->nh.raw = &top_iph->nexthdr;
59 skb->h.ipv6h = top_iph + 1;
60
61 top_iph->version = 6;
62 top_iph->priority = iph->priority;
63 top_iph->flow_lbl[0] = iph->flow_lbl[0];
64 top_iph->flow_lbl[1] = iph->flow_lbl[1];
65 top_iph->flow_lbl[2] = iph->flow_lbl[2];
66 dsfield = ipv6_get_dsfield(top_iph);
67 dsfield = INET_ECN_encapsulate(dsfield, dsfield);
68 if (x->props.flags & XFRM_STATE_NOECN)
69 dsfield &= ~INET_ECN_MASK;
70 ipv6_change_dsfield(top_iph, 0, dsfield);
71 top_iph->nexthdr = IPPROTO_IPV6;
72 top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
73 ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
74 ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
75}
76
77static int xfrm6_tunnel_check_size(struct sk_buff *skb)
78{
79 int mtu, ret = 0;
80 struct dst_entry *dst = skb->dst;
81
82 mtu = dst_mtu(dst);
83 if (mtu < IPV6_MIN_MTU)
84 mtu = IPV6_MIN_MTU;
85
86 if (skb->len > mtu) {
Herbert Xu180e4252005-05-23 13:11:07 -070087 skb->dev = dst->dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
89 ret = -EMSGSIZE;
90 }
91
92 return ret;
93}
94
95int xfrm6_output(struct sk_buff *skb)
96{
97 struct dst_entry *dst = skb->dst;
98 struct xfrm_state *x = dst->xfrm;
99 int err;
100
101 if (skb->ip_summed == CHECKSUM_HW) {
102 err = skb_checksum_help(skb, 0);
103 if (err)
104 goto error_nolock;
105 }
106
107 if (x->props.mode) {
108 err = xfrm6_tunnel_check_size(skb);
109 if (err)
110 goto error_nolock;
111 }
112
113 spin_lock_bh(&x->lock);
114 err = xfrm_state_check(x, skb);
115 if (err)
116 goto error;
117
118 xfrm6_encap(skb);
119
120 err = x->type->output(x, skb);
121 if (err)
122 goto error;
123
124 x->curlft.bytes += skb->len;
125 x->curlft.packets++;
126
127 spin_unlock_bh(&x->lock);
128
129 skb->nh.raw = skb->data;
130
131 if (!(skb->dst = dst_pop(dst))) {
132 err = -EHOSTUNREACH;
133 goto error_nolock;
134 }
135 err = NET_XMIT_BYPASS;
136
137out_exit:
138 return err;
139error:
140 spin_unlock_bh(&x->lock);
141error_nolock:
142 kfree_skb(skb);
143 goto out_exit;
144}