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										 |  |  | /*
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							|  |  |  |  * xfrm4_output.c - Common IPsec encapsulation code for IPv4. | 
					
						
							|  |  |  |  * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> | 
					
						
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										 |  |  |  * | 
					
						
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										 |  |  |  * This program is free software; you can redistribute it and/or | 
					
						
							|  |  |  |  * modify it under the terms of the GNU General Public License | 
					
						
							|  |  |  |  * as published by the Free Software Foundation; either version | 
					
						
							|  |  |  |  * 2 of the License, or (at your option) any later version. | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | 
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										 |  |  | #include <linux/if_ether.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/netfilter_ipv4.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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							|  |  |  | #include <net/icmp.h>
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							|  |  |  | static int xfrm4_tunnel_check_size(struct sk_buff *skb) | 
					
						
							|  |  |  | { | 
					
						
							|  |  |  | 	int mtu, ret = 0; | 
					
						
							|  |  |  | 	struct dst_entry *dst; | 
					
						
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							|  |  |  | 	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) | 
					
						
							|  |  |  | 		goto out; | 
					
						
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										 |  |  | 	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df) | 
					
						
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										 |  |  | 		goto out; | 
					
						
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							|  |  |  | 	dst = skb->dst; | 
					
						
							|  |  |  | 	mtu = dst_mtu(dst); | 
					
						
							|  |  |  | 	if (skb->len > mtu) { | 
					
						
							|  |  |  | 		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); | 
					
						
							|  |  |  | 		ret = -EMSGSIZE; | 
					
						
							|  |  |  | 	} | 
					
						
							|  |  |  | out: | 
					
						
							|  |  |  | 	return ret; | 
					
						
							|  |  |  | } | 
					
						
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										 |  |  | int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb) | 
					
						
							|  |  |  | { | 
					
						
							|  |  |  | 	int err; | 
					
						
							|  |  |  | 
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							|  |  |  | 	err = xfrm4_tunnel_check_size(skb); | 
					
						
							|  |  |  | 	if (err) | 
					
						
							|  |  |  | 		return err; | 
					
						
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										 |  |  | 	XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol; | 
					
						
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										 |  |  | 	return xfrm4_extract_header(skb); | 
					
						
							|  |  |  | } | 
					
						
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							|  |  |  | int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb) | 
					
						
							|  |  |  | { | 
					
						
							|  |  |  | 	int err; | 
					
						
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							|  |  |  | 	err = x->inner_mode->afinfo->extract_output(x, skb); | 
					
						
							|  |  |  | 	if (err) | 
					
						
							|  |  |  | 		return err; | 
					
						
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							|  |  |  | 	memset(IPCB(skb), 0, sizeof(*IPCB(skb))); | 
					
						
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										 |  |  | 	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED; | 
					
						
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							|  |  |  | 	skb->protocol = htons(ETH_P_IP); | 
					
						
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							|  |  |  | 	return x->outer_mode->output2(x, skb); | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | EXPORT_SYMBOL(xfrm4_prepare_output); | 
					
						
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										 |  |  | static int xfrm4_output_finish(struct sk_buff *skb) | 
					
						
							|  |  |  | { | 
					
						
							|  |  |  | #ifdef CONFIG_NETFILTER
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							|  |  |  | 	if (!skb->dst->xfrm) { | 
					
						
							|  |  |  | 		IPCB(skb)->flags |= IPSKB_REROUTED; | 
					
						
							|  |  |  | 		return dst_output(skb); | 
					
						
							|  |  |  | 	} | 
					
						
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										 |  |  | 	IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; | 
					
						
							|  |  |  | #endif
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										 |  |  | 
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							|  |  |  | 	skb->protocol = htons(ETH_P_IP); | 
					
						
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										 |  |  | 	return xfrm_output(skb); | 
					
						
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										 |  |  | } | 
					
						
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										 |  |  | int xfrm4_output(struct sk_buff *skb) | 
					
						
							|  |  |  | { | 
					
						
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										 |  |  | 	return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb, | 
					
						
							|  |  |  | 			    NULL, skb->dst->dev, xfrm4_output_finish, | 
					
						
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										 |  |  | 			    !(IPCB(skb)->flags & IPSKB_REROUTED)); | 
					
						
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										 |  |  | } |