[IPSEC]: Move IP length/checksum setting out of transforms
[linux-2.6.git] / net / ipv4 / xfrm4_output.c
1 /*
2  * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
3  * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License
7  * as published by the Free Software Foundation; either version
8  * 2 of the License, or (at your option) any later version.
9  */
10
11 #include <linux/compiler.h>
12 #include <linux/if_ether.h>
13 #include <linux/kernel.h>
14 #include <linux/skbuff.h>
15 #include <linux/netfilter_ipv4.h>
16 #include <net/ip.h>
17 #include <net/xfrm.h>
18 #include <net/icmp.h>
19
20 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
21 {
22         int mtu, ret = 0;
23         struct dst_entry *dst;
24
25         if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
26                 goto out;
27
28         IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
29
30         if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
31                 goto out;
32
33         dst = skb->dst;
34         mtu = dst_mtu(dst);
35         if (skb->len > mtu) {
36                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
37                 ret = -EMSGSIZE;
38         }
39 out:
40         return ret;
41 }
42
43 static inline int xfrm4_output_one(struct sk_buff *skb)
44 {
45         struct dst_entry *dst = skb->dst;
46         struct xfrm_state *x = dst->xfrm;
47         struct iphdr *iph;
48         int err;
49
50         if (x->props.mode == XFRM_MODE_TUNNEL) {
51                 err = xfrm4_tunnel_check_size(skb);
52                 if (err)
53                         goto error_nolock;
54         }
55
56         err = xfrm_output(skb);
57         if (err)
58                 goto error_nolock;
59
60         iph = ip_hdr(skb);
61         iph->tot_len = htons(skb->len);
62         ip_send_check(iph);
63
64         IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
65         err = 0;
66
67 out_exit:
68         return err;
69 error_nolock:
70         kfree_skb(skb);
71         goto out_exit;
72 }
73
74 static int xfrm4_output_finish2(struct sk_buff *skb)
75 {
76         int err;
77
78         while (likely((err = xfrm4_output_one(skb)) == 0)) {
79                 nf_reset(skb);
80
81                 err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL,
82                               skb->dst->dev, dst_output);
83                 if (unlikely(err != 1))
84                         break;
85
86                 if (!skb->dst->xfrm)
87                         return dst_output(skb);
88
89                 err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL,
90                               skb->dst->dev, xfrm4_output_finish2);
91                 if (unlikely(err != 1))
92                         break;
93         }
94
95         return err;
96 }
97
98 static int xfrm4_output_finish(struct sk_buff *skb)
99 {
100         struct sk_buff *segs;
101
102 #ifdef CONFIG_NETFILTER
103         if (!skb->dst->xfrm) {
104                 IPCB(skb)->flags |= IPSKB_REROUTED;
105                 return dst_output(skb);
106         }
107 #endif
108
109         if (!skb_is_gso(skb))
110                 return xfrm4_output_finish2(skb);
111
112         skb->protocol = htons(ETH_P_IP);
113         segs = skb_gso_segment(skb, 0);
114         kfree_skb(skb);
115         if (unlikely(IS_ERR(segs)))
116                 return PTR_ERR(segs);
117
118         do {
119                 struct sk_buff *nskb = segs->next;
120                 int err;
121
122                 segs->next = NULL;
123                 err = xfrm4_output_finish2(segs);
124
125                 if (unlikely(err)) {
126                         while ((segs = nskb)) {
127                                 nskb = segs->next;
128                                 segs->next = NULL;
129                                 kfree_skb(segs);
130                         }
131                         return err;
132                 }
133
134                 segs = nskb;
135         } while (segs);
136
137         return 0;
138 }
139
140 int xfrm4_output(struct sk_buff *skb)
141 {
142         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
143                             xfrm4_output_finish,
144                             !(IPCB(skb)->flags & IPSKB_REROUTED));
145 }