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 static int xfrm4_transport_output(struct xfrm_state
*x
, struct sk_buff
*skb
)
23 struct iphdr
*iph
= ip_hdr(skb
);
24 int ihl
= iph
->ihl
* 4;
26 skb_set_network_header(skb
, -x
->props
.header_len
);
27 skb
->mac_header
= skb
->network_header
+
28 offsetof(struct iphdr
, protocol
);
29 skb
->transport_header
= skb
->network_header
+ ihl
;
31 memmove(skb_network_header(skb
), iph
, ihl
);
35 /* Remove encapsulation header.
37 * The IP header will be moved over the top of the encapsulation header.
39 * On entry, skb->h shall point to where the IP header should be and skb->nh
40 * shall be set to where the IP header currently is. skb->data shall point
41 * to the start of the payload.
43 static int xfrm4_transport_input(struct xfrm_state
*x
, struct sk_buff
*skb
)
45 int ihl
= skb
->data
- skb_transport_header(skb
);
46 struct xfrm_offload
*xo
= xfrm_offload(skb
);
48 if (skb
->transport_header
!= skb
->network_header
) {
49 memmove(skb_transport_header(skb
),
50 skb_network_header(skb
), ihl
);
51 skb
->network_header
= skb
->transport_header
;
53 ip_hdr(skb
)->tot_len
= htons(skb
->len
+ ihl
);
54 if (!xo
|| !(xo
->flags
& XFRM_GRO
))
55 skb_reset_transport_header(skb
);
59 static struct xfrm_mode xfrm4_transport_mode
= {
60 .input
= xfrm4_transport_input
,
61 .output
= xfrm4_transport_output
,
63 .encap
= XFRM_MODE_TRANSPORT
,
66 static int __init
xfrm4_transport_init(void)
68 return xfrm_register_mode(&xfrm4_transport_mode
, AF_INET
);
71 static void __exit
xfrm4_transport_exit(void)
75 err
= xfrm_unregister_mode(&xfrm4_transport_mode
, AF_INET
);
79 module_init(xfrm4_transport_init
);
80 module_exit(xfrm4_transport_exit
);
81 MODULE_LICENSE("GPL");
82 MODULE_ALIAS_XFRM_MODE(AF_INET
, XFRM_MODE_TRANSPORT
);