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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/net/ipv6/xfrm6_mode_transport.c
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/*

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 * xfrm6_mode_transport.c - Transport mode encapsulation for IPv6.

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 *

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 * Copyright (C) 2002 USAGI/WIDE Project

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 * Copyright (c) 2004-2006 Herbert Xu <[email protected]>

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 */

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#include <linux/init.h>

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#include <linux/kernel.h>

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#include <linux/module.h>

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#include <linux/skbuff.h>

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#include <linux/stringify.h>

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#include <net/dst.h>

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#include <net/ipv6.h>

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#include <net/xfrm.h>

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/* Add encapsulation header.

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 *

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 * The IP header and mutable extension headers will be moved forward to make

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 * space for the encapsulation header.

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 */

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static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)

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{

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	struct ipv6hdr *iph;

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	u8 *prevhdr;

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	int hdr_len;

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	iph = ipv6_hdr(skb);

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	hdr_len = x->type->hdr_offset(x, skb, &prevhdr);

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	skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);

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	skb_set_network_header(skb, -x->props.header_len);

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	skb->transport_header = skb->network_header + hdr_len;

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	__skb_pull(skb, hdr_len);

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	memmove(ipv6_hdr(skb), iph, hdr_len);

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	return 0;

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}

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/* Remove encapsulation header.

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 *

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 * The IP header will be moved over the top of the encapsulation header.

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 *

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 * On entry, skb->h shall point to where the IP header should be and skb->nh

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 * shall be set to where the IP header currently is.  skb->data shall point

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 * to the start of the payload.

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 */

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static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)

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{

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	int ihl = skb->data - skb_transport_header(skb);

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	if (skb->transport_header != skb->network_header) {

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		memmove(skb_transport_header(skb),

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			skb_network_header(skb), ihl);

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		skb->network_header = skb->transport_header;

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	}

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	ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -

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					   sizeof(struct ipv6hdr));

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	skb_reset_transport_header(skb);

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	return 0;

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}

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static struct xfrm_mode xfrm6_transport_mode = {

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	.input = xfrm6_transport_input,

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	.output = xfrm6_transport_output,

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	.owner = THIS_MODULE,

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	.encap = XFRM_MODE_TRANSPORT,

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};

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static int __init xfrm6_transport_init(void)

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{

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	return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6);

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}

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static void __exit xfrm6_transport_exit(void)

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{

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	int err;

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	err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6);

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	BUG_ON(err);

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}

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module_init(xfrm6_transport_init);

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module_exit(xfrm6_transport_exit);

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MODULE_LICENSE("GPL");

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MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT);

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