[IPSEC]: Separate inner/outer mode processing on output
[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/if_ether.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/netfilter_ipv4.h>
16 #include <net/dst.h>
17 #include <net/ip.h>
18 #include <net/xfrm.h>
19 #include <net/icmp.h>
20
21 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
22 {
23         int mtu, ret = 0;
24         struct dst_entry *dst;
25
26         if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
27                 goto out;
28
29         if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
30                 goto out;
31
32         dst = skb->dst;
33         mtu = dst_mtu(dst);
34         if (skb->len > mtu) {
35                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
36                 ret = -EMSGSIZE;
37         }
38 out:
39         return ret;
40 }
41
42 int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
43 {
44         int err;
45
46         err = xfrm4_tunnel_check_size(skb);
47         if (err)
48                 return err;
49
50         return xfrm4_extract_header(skb);
51 }
52
53 int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
54 {
55         int err;
56
57         err = x->inner_mode->afinfo->extract_output(x, skb);
58         if (err)
59                 return err;
60
61         memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
62         IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
63
64         skb->protocol = htons(ETH_P_IP);
65
66         return x->outer_mode->output2(x, skb);
67 }
68 EXPORT_SYMBOL(xfrm4_prepare_output);
69
70 static inline int xfrm4_output_one(struct sk_buff *skb)
71 {
72         struct iphdr *iph;
73         int err;
74
75         err = xfrm_output(skb);
76         if (err)
77                 goto error_nolock;
78
79         iph = ip_hdr(skb);
80         iph->tot_len = htons(skb->len);
81         ip_send_check(iph);
82
83         IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
84         err = 0;
85
86 out_exit:
87         return err;
88 error_nolock:
89         kfree_skb(skb);
90         goto out_exit;
91 }
92
93 static int xfrm4_output_finish2(struct sk_buff *skb)
94 {
95         int err;
96
97         while (likely((err = xfrm4_output_one(skb)) == 0)) {
98                 nf_reset(skb);
99
100                 err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
101                               skb->dst->dev, dst_output);
102                 if (unlikely(err != 1))
103                         break;
104
105                 if (!skb->dst->xfrm)
106                         return dst_output(skb);
107
108                 err = nf_hook(PF_INET, NF_IP_POST_ROUTING, skb, NULL,
109                               skb->dst->dev, xfrm4_output_finish2);
110                 if (unlikely(err != 1))
111                         break;
112         }
113
114         return err;
115 }
116
117 static int xfrm4_output_finish(struct sk_buff *skb)
118 {
119         struct sk_buff *segs;
120
121 #ifdef CONFIG_NETFILTER
122         if (!skb->dst->xfrm) {
123                 IPCB(skb)->flags |= IPSKB_REROUTED;
124                 return dst_output(skb);
125         }
126 #endif
127
128         if (!skb_is_gso(skb))
129                 return xfrm4_output_finish2(skb);
130
131         skb->protocol = htons(ETH_P_IP);
132         segs = skb_gso_segment(skb, 0);
133         kfree_skb(skb);
134         if (unlikely(IS_ERR(segs)))
135                 return PTR_ERR(segs);
136
137         do {
138                 struct sk_buff *nskb = segs->next;
139                 int err;
140
141                 segs->next = NULL;
142                 err = xfrm4_output_finish2(segs);
143
144                 if (unlikely(err)) {
145                         while ((segs = nskb)) {
146                                 nskb = segs->next;
147                                 segs->next = NULL;
148                                 kfree_skb(segs);
149                         }
150                         return err;
151                 }
152
153                 segs = nskb;
154         } while (segs);
155
156         return 0;
157 }
158
159 int xfrm4_output(struct sk_buff *skb)
160 {
161         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
162                             xfrm4_output_finish,
163                             !(IPCB(skb)->flags & IPSKB_REROUTED));
164 }