[XFRM] STATE: Add a hook to find offset to be inserted header in outbound.
[linux-2.6.git] / net / ipv6 / xfrm6_output.c
1 /*
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/compiler.h>
13 #include <linux/skbuff.h>
14 #include <linux/spinlock.h>
15 #include <linux/icmpv6.h>
16 #include <linux/netfilter_ipv6.h>
17 #include <net/ipv6.h>
18 #include <net/xfrm.h>
19
20 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
21                           u8 **prevhdr)
22 {
23         return ip6_find_1stfragopt(skb, prevhdr);
24 }
25
26 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
27 {
28         int mtu, ret = 0;
29         struct dst_entry *dst = skb->dst;
30
31         mtu = dst_mtu(dst);
32         if (mtu < IPV6_MIN_MTU)
33                 mtu = IPV6_MIN_MTU;
34
35         if (skb->len > mtu) {
36                 skb->dev = dst->dev;
37                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
38                 ret = -EMSGSIZE;
39         }
40
41         return ret;
42 }
43
44 static int xfrm6_output_one(struct sk_buff *skb)
45 {
46         struct dst_entry *dst = skb->dst;
47         struct xfrm_state *x = dst->xfrm;
48         int err;
49         
50         if (skb->ip_summed == CHECKSUM_PARTIAL) {
51                 err = skb_checksum_help(skb);
52                 if (err)
53                         goto error_nolock;
54         }
55
56         if (x->props.mode == XFRM_MODE_TUNNEL) {
57                 err = xfrm6_tunnel_check_size(skb);
58                 if (err)
59                         goto error_nolock;
60         }
61
62         do {
63                 spin_lock_bh(&x->lock);
64                 err = xfrm_state_check(x, skb);
65                 if (err)
66                         goto error;
67
68                 err = x->mode->output(skb);
69                 if (err)
70                         goto error;
71
72                 err = x->type->output(x, skb);
73                 if (err)
74                         goto error;
75
76                 x->curlft.bytes += skb->len;
77                 x->curlft.packets++;
78
79                 spin_unlock_bh(&x->lock);
80
81                 skb->nh.raw = skb->data;
82                 
83                 if (!(skb->dst = dst_pop(dst))) {
84                         err = -EHOSTUNREACH;
85                         goto error_nolock;
86                 }
87                 dst = skb->dst;
88                 x = dst->xfrm;
89         } while (x && (x->props.mode != XFRM_MODE_TUNNEL));
90
91         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
92         err = 0;
93
94 out_exit:
95         return err;
96 error:
97         spin_unlock_bh(&x->lock);
98 error_nolock:
99         kfree_skb(skb);
100         goto out_exit;
101 }
102
103 static int xfrm6_output_finish2(struct sk_buff *skb)
104 {
105         int err;
106
107         while (likely((err = xfrm6_output_one(skb)) == 0)) {
108                 nf_reset(skb);
109         
110                 err = nf_hook(PF_INET6, NF_IP6_LOCAL_OUT, &skb, NULL,
111                               skb->dst->dev, dst_output);
112                 if (unlikely(err != 1))
113                         break;
114
115                 if (!skb->dst->xfrm)
116                         return dst_output(skb);
117
118                 err = nf_hook(PF_INET6, NF_IP6_POST_ROUTING, &skb, NULL,
119                               skb->dst->dev, xfrm6_output_finish2);
120                 if (unlikely(err != 1))
121                         break;
122         }
123
124         return err;
125 }
126
127 static int xfrm6_output_finish(struct sk_buff *skb)
128 {
129         struct sk_buff *segs;
130
131         if (!skb_is_gso(skb))
132                 return xfrm6_output_finish2(skb);
133
134         skb->protocol = htons(ETH_P_IPV6);
135         segs = skb_gso_segment(skb, 0);
136         kfree_skb(skb);
137         if (unlikely(IS_ERR(segs)))
138                 return PTR_ERR(segs);
139
140         do {
141                 struct sk_buff *nskb = segs->next;
142                 int err;
143
144                 segs->next = NULL;
145                 err = xfrm6_output_finish2(segs);
146
147                 if (unlikely(err)) {
148                         while ((segs = nskb)) {
149                                 nskb = segs->next;
150                                 segs->next = NULL;
151                                 kfree_skb(segs);
152                         }
153                         return err;
154                 }
155
156                 segs = nskb;
157         } while (segs);
158
159         return 0;
160 }
161
162 int xfrm6_output(struct sk_buff *skb)
163 {
164         return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL, skb->dst->dev,
165                        xfrm6_output_finish);
166 }