blob: 80242172a5df260815b087bd80f6160c71615119 [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
Patrick McHardy16a66772006-01-06 23:01:48 -080012#include <linux/compiler.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/skbuff.h>
14#include <linux/spinlock.h>
15#include <linux/icmpv6.h>
Patrick McHardy16a66772006-01-06 23:01:48 -080016#include <linux/netfilter_ipv6.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <net/dsfield.h>
18#include <net/inet_ecn.h>
19#include <net/ipv6.h>
20#include <net/xfrm.h>
21
22/* Add encapsulation header.
23 *
24 * In transport mode, the IP header and mutable extension headers will be moved
25 * forward to make space for the encapsulation header.
26 *
27 * In tunnel mode, the top IP header will be constructed per RFC 2401.
28 * The following fields in it shall be filled in by x->type->output:
29 * payload_len
30 *
31 * On exit, skb->h will be set to the start of the encapsulation header to be
32 * filled in by x->type->output and skb->nh will be set to the nextheader field
33 * of the extension header directly preceding the encapsulation header, or in
34 * its absence, that of the top IP header. The value of skb->data will always
35 * point to the top IP header.
36 */
37static void xfrm6_encap(struct sk_buff *skb)
38{
39 struct dst_entry *dst = skb->dst;
40 struct xfrm_state *x = dst->xfrm;
41 struct ipv6hdr *iph, *top_iph;
42 int dsfield;
43
44 skb_push(skb, x->props.header_len);
45 iph = skb->nh.ipv6h;
46
47 if (!x->props.mode) {
48 u8 *prevhdr;
49 int hdr_len;
50
51 hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
52 skb->nh.raw = prevhdr - x->props.header_len;
53 skb->h.raw = skb->data + hdr_len;
54 memmove(skb->data, iph, hdr_len);
55 return;
56 }
57
58 skb->nh.raw = skb->data;
59 top_iph = skb->nh.ipv6h;
60 skb->nh.raw = &top_iph->nexthdr;
61 skb->h.ipv6h = top_iph + 1;
62
63 top_iph->version = 6;
64 top_iph->priority = iph->priority;
65 top_iph->flow_lbl[0] = iph->flow_lbl[0];
66 top_iph->flow_lbl[1] = iph->flow_lbl[1];
67 top_iph->flow_lbl[2] = iph->flow_lbl[2];
68 dsfield = ipv6_get_dsfield(top_iph);
69 dsfield = INET_ECN_encapsulate(dsfield, dsfield);
70 if (x->props.flags & XFRM_STATE_NOECN)
71 dsfield &= ~INET_ECN_MASK;
72 ipv6_change_dsfield(top_iph, 0, dsfield);
73 top_iph->nexthdr = IPPROTO_IPV6;
74 top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
75 ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
76 ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
77}
78
79static int xfrm6_tunnel_check_size(struct sk_buff *skb)
80{
81 int mtu, ret = 0;
82 struct dst_entry *dst = skb->dst;
83
84 mtu = dst_mtu(dst);
85 if (mtu < IPV6_MIN_MTU)
86 mtu = IPV6_MIN_MTU;
87
88 if (skb->len > mtu) {
Herbert Xu180e4252005-05-23 13:11:07 -070089 skb->dev = dst->dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
91 ret = -EMSGSIZE;
92 }
93
94 return ret;
95}
96
Patrick McHardy16a66772006-01-06 23:01:48 -080097static int xfrm6_output_one(struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -070098{
99 struct dst_entry *dst = skb->dst;
100 struct xfrm_state *x = dst->xfrm;
101 int err;
102
103 if (skb->ip_summed == CHECKSUM_HW) {
104 err = skb_checksum_help(skb, 0);
105 if (err)
106 goto error_nolock;
107 }
108
109 if (x->props.mode) {
110 err = xfrm6_tunnel_check_size(skb);
111 if (err)
112 goto error_nolock;
113 }
114
Patrick McHardy16a66772006-01-06 23:01:48 -0800115 do {
116 spin_lock_bh(&x->lock);
117 err = xfrm_state_check(x, skb);
118 if (err)
119 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
Patrick McHardy16a66772006-01-06 23:01:48 -0800121 xfrm6_encap(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122
Patrick McHardy16a66772006-01-06 23:01:48 -0800123 err = x->type->output(x, skb);
124 if (err)
125 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
Patrick McHardy16a66772006-01-06 23:01:48 -0800127 x->curlft.bytes += skb->len;
128 x->curlft.packets++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
Patrick McHardy16a66772006-01-06 23:01:48 -0800130 spin_unlock_bh(&x->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
Patrick McHardy16a66772006-01-06 23:01:48 -0800132 skb->nh.raw = skb->data;
133
134 if (!(skb->dst = dst_pop(dst))) {
135 err = -EHOSTUNREACH;
136 goto error_nolock;
137 }
138 dst = skb->dst;
139 x = dst->xfrm;
140 } while (x && !x->props.mode);
141
Patrick McHardy3e3850e2006-01-06 23:04:54 -0800142 IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
Patrick McHardy16a66772006-01-06 23:01:48 -0800143 err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
145out_exit:
146 return err;
147error:
148 spin_unlock_bh(&x->lock);
149error_nolock:
150 kfree_skb(skb);
151 goto out_exit;
152}
Patrick McHardy16a66772006-01-06 23:01:48 -0800153
154static int xfrm6_output_finish(struct sk_buff *skb)
155{
156 int err;
157
158 while (likely((err = xfrm6_output_one(skb)) == 0)) {
159 nf_reset(skb);
160
161 err = nf_hook(PF_INET6, NF_IP6_LOCAL_OUT, &skb, NULL,
162 skb->dst->dev, dst_output);
163 if (unlikely(err != 1))
164 break;
165
166 if (!skb->dst->xfrm)
167 return dst_output(skb);
168
169 err = nf_hook(PF_INET6, NF_IP6_POST_ROUTING, &skb, NULL,
170 skb->dst->dev, xfrm6_output_finish);
171 if (unlikely(err != 1))
172 break;
173 }
174
175 return err;
176}
177
178int xfrm6_output(struct sk_buff *skb)
179{
180 return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL, skb->dst->dev,
181 xfrm6_output_finish);
182}