124 lines
3.0 KiB
C
124 lines
3.0 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/gfp.h>
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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 *inner_iph = ipip_hdr(skb);
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if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->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.
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*/
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static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct dst_entry *dst = skb_dst(skb);
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struct iphdr *top_iph;
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int flags;
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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 + sizeof(*top_iph);
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top_iph = ip_hdr(skb);
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top_iph->ihl = 5;
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top_iph->version = 4;
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top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
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/* DS disclosed */
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top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos,
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XFRM_MODE_SKB_CB(skb)->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 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
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ip_select_ident(top_iph, dst->child, NULL);
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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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return 0;
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}
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static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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const unsigned char *old_mac;
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int err = -EINVAL;
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if (XFRM_MODE_SKB_CB(skb)->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(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb));
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if (!(x->props.flags & XFRM_STATE_NOECN))
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ipip_ecn_decapsulate(skb);
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old_mac = skb_mac_header(skb);
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skb_set_mac_header(skb, -skb->mac_len);
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memmove(skb_mac_header(skb), old_mac, skb->mac_len);
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skb_reset_network_header(skb);
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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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.input2 = xfrm4_mode_tunnel_input,
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.input = xfrm_prepare_input,
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.output2 = xfrm4_mode_tunnel_output,
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.output = xfrm4_prepare_output,
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.owner = THIS_MODULE,
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.encap = XFRM_MODE_TUNNEL,
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.flags = XFRM_MODE_FLAG_TUNNEL,
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};
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static int __init xfrm4_mode_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_mode_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_mode_tunnel_init);
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module_exit(xfrm4_mode_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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