2 * xfrm4_mode_transport.c - Transport mode encapsulation for IPv4.
4 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
7 #include <linux/init.h>
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <linux/stringify.h>
16 /* Add encapsulation header.
18 * The IP header will be moved forward to make space for the encapsulation
21 * On exit, skb->h will be set to the start of the payload to be processed
22 * by x->type->output and skb->nh will be set to the top IP header.
24 static int xfrm4_transport_output(struct xfrm_state
*x
, struct sk_buff
*skb
)
35 skb_push(skb
, x
->props
.header_len
);
36 skb_reset_network_header(skb
);
37 memmove(skb
->nh
.raw
, iph
, ihl
);
41 /* Remove encapsulation header.
43 * The IP header will be moved over the top of the encapsulation header.
45 * On entry, skb->h shall point to where the IP header should be and skb->nh
46 * shall be set to where the IP header currently is. skb->data shall point
47 * to the start of the payload.
49 static int xfrm4_transport_input(struct xfrm_state
*x
, struct sk_buff
*skb
)
51 int ihl
= skb
->data
- skb
->h
.raw
;
53 if (skb
->h
.raw
!= skb
->nh
.raw
) {
54 memmove(skb
->h
.raw
, skb
->nh
.raw
, ihl
);
55 skb
->nh
.raw
= skb
->h
.raw
;
57 skb
->nh
.iph
->tot_len
= htons(skb
->len
+ ihl
);
58 skb
->h
.raw
= skb
->data
;
62 static struct xfrm_mode xfrm4_transport_mode
= {
63 .input
= xfrm4_transport_input
,
64 .output
= xfrm4_transport_output
,
66 .encap
= XFRM_MODE_TRANSPORT
,
69 static int __init
xfrm4_transport_init(void)
71 return xfrm_register_mode(&xfrm4_transport_mode
, AF_INET
);
74 static void __exit
xfrm4_transport_exit(void)
78 err
= xfrm_unregister_mode(&xfrm4_transport_mode
, AF_INET
);
82 module_init(xfrm4_transport_init
);
83 module_exit(xfrm4_transport_exit
);
84 MODULE_LICENSE("GPL");
85 MODULE_ALIAS_XFRM_MODE(AF_INET
, XFRM_MODE_TRANSPORT
);