81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
/*
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* xfrm4_mode_transport.c - Transport mode encapsulation for IPv4.
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*
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* Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
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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/ip.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 will be moved forward to make space for the encapsulation
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* header.
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*/
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static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct iphdr *iph = ip_hdr(skb);
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int ihl = iph->ihl * 4;
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skb_set_network_header(skb, -x->props.header_len);
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skb->mac_header = skb->network_header +
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offsetof(struct iphdr, protocol);
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skb->transport_header = skb->network_header + ihl;
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__skb_pull(skb, ihl);
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memmove(skb_network_header(skb), iph, ihl);
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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 xfrm4_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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ip_hdr(skb)->tot_len = htons(skb->len + ihl);
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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 xfrm4_transport_mode = {
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.input = xfrm4_transport_input,
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.output = xfrm4_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 xfrm4_transport_init(void)
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{
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return xfrm_register_mode(&xfrm4_transport_mode, AF_INET);
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}
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static void __exit xfrm4_transport_exit(void)
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{
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int err;
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err = xfrm_unregister_mode(&xfrm4_transport_mode, AF_INET);
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BUG_ON(err);
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}
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module_init(xfrm4_transport_init);
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module_exit(xfrm4_transport_exit);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TRANSPORT);
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