124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
/*
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* xfrm4_mode_tunnel.c - Tunnel 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/inet_ecn.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
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{
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struct iphdr *outer_iph = skb->nh.iph;
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struct iphdr *inner_iph = skb->h.ipiph;
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if (INET_ECN_is_ce(outer_iph->tos))
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IP_ECN_set_ce(inner_iph);
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}
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/* Add encapsulation header.
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*
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* The top IP header will be constructed per RFC 2401. The following fields
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* in it shall be filled in by x->type->output:
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* tot_len
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* check
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*
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* On exit, skb->h will be set to the start of the payload to be processed
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* by x->type->output and skb->nh will be set to the top IP header.
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*/
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static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct dst_entry *dst = skb->dst;
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struct iphdr *iph, *top_iph;
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int flags;
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iph = skb->nh.iph;
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skb->h.ipiph = iph;
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skb->nh.raw = skb_push(skb, x->props.header_len);
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top_iph = skb->nh.iph;
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top_iph->ihl = 5;
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top_iph->version = 4;
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/* DS disclosed */
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top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
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flags = x->props.flags;
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if (flags & XFRM_STATE_NOECN)
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IP_ECN_clear(top_iph);
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top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
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0 : (iph->frag_off & htons(IP_DF));
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if (!top_iph->frag_off)
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__ip_select_ident(top_iph, dst->child, 0);
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top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
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top_iph->saddr = x->props.saddr.a4;
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top_iph->daddr = x->id.daddr.a4;
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top_iph->protocol = IPPROTO_IPIP;
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memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
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return 0;
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}
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static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct iphdr *iph = skb->nh.iph;
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int err = -EINVAL;
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if (iph->protocol != IPPROTO_IPIP)
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goto out;
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if (!pskb_may_pull(skb, sizeof(struct iphdr)))
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goto out;
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if (skb_cloned(skb) &&
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(err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
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goto out;
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if (x->props.flags & XFRM_STATE_DECAP_DSCP)
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ipv4_copy_dscp(iph, skb->h.ipiph);
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if (!(x->props.flags & XFRM_STATE_NOECN))
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ipip_ecn_decapsulate(skb);
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skb->mac.raw = memmove(skb->data - skb->mac_len,
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skb->mac.raw, skb->mac_len);
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skb->nh.raw = skb->data;
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err = 0;
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out:
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return err;
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}
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static struct xfrm_mode xfrm4_tunnel_mode = {
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.input = xfrm4_tunnel_input,
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.output = xfrm4_tunnel_output,
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.owner = THIS_MODULE,
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.encap = XFRM_MODE_TUNNEL,
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};
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static int __init xfrm4_tunnel_init(void)
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{
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return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
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}
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static void __exit xfrm4_tunnel_exit(void)
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{
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int err;
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err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
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BUG_ON(err);
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}
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module_init(xfrm4_tunnel_init);
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module_exit(xfrm4_tunnel_exit);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);
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