[net-next-2.6.git] / net / ipv4 / xfrm4_output.c

/*
 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
 * 
 * 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.
 */

#include <linux/compiler.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/netfilter_ipv4.h>
#include <net/inet_ecn.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/icmp.h>

/* Add encapsulation header.
 *
 * In transport mode, the IP header will be moved forward to make space
 * for the encapsulation header.
 *
 * In tunnel mode, the top IP header will be constructed per RFC 2401.
 * The following fields in it shall be filled in by x->type->output:
 *	tot_len
 *	check
 *
 * On exit, skb->h will be set to the start of the payload to be processed
 * by x->type->output and skb->nh will be set to the top IP header.
 */
static void xfrm4_encap(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct xfrm_state *x = dst->xfrm;
	struct iphdr *iph, *top_iph;
	int flags;

	iph = skb->nh.iph;
	skb->h.ipiph = iph;

	skb->nh.raw = skb_push(skb, x->props.header_len);
	top_iph = skb->nh.iph;

	if (!x->props.mode) {
		skb->h.raw += iph->ihl*4;
		memmove(top_iph, iph, iph->ihl*4);
		return;
	}

	top_iph->ihl = 5;
	top_iph->version = 4;

	/* DS disclosed */
	top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);

	flags = x->props.flags;
	if (flags & XFRM_STATE_NOECN)
		IP_ECN_clear(top_iph);

	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
		0 : (iph->frag_off & htons(IP_DF));
	if (!top_iph->frag_off)
		__ip_select_ident(top_iph, dst, 0);

	top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);

	top_iph->saddr = x->props.saddr.a4;
	top_iph->daddr = x->id.daddr.a4;
	top_iph->protocol = IPPROTO_IPIP;

	memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
}

static int xfrm4_tunnel_check_size(struct sk_buff *skb)
{
	int mtu, ret = 0;
	struct dst_entry *dst;
	struct iphdr *iph = skb->nh.iph;

	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
		goto out;

	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
	
	if (!(iph->frag_off & htons(IP_DF)) || skb->local_df)
		goto out;

	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;
}

static int xfrm4_output_one(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct xfrm_state *x = dst->xfrm;
	int err;
	
	if (skb->ip_summed == CHECKSUM_HW) {
		err = skb_checksum_help(skb, 0);
		if (err)
			goto error_nolock;
	}

	if (x->props.mode) {
		err = xfrm4_tunnel_check_size(skb);
		if (err)
			goto error_nolock;
	}

	do {
		spin_lock_bh(&x->lock);
		err = xfrm_state_check(x, skb);
		if (err)
			goto error;

		xfrm4_encap(skb);

		err = x->type->output(x, skb);
		if (err)
			goto error;

		x->curlft.bytes += skb->len;
		x->curlft.packets++;

		spin_unlock_bh(&x->lock);
	
		if (!(skb->dst = dst_pop(dst))) {
			err = -EHOSTUNREACH;
			goto error_nolock;
		}
		dst = skb->dst;
		x = dst->xfrm;
	} while (x && !x->props.mode);

	IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
	err = 0;

out_exit:
	return err;
error:
	spin_unlock_bh(&x->lock);
error_nolock:
	kfree_skb(skb);
	goto out_exit;
}

int xfrm4_output_finish(struct sk_buff *skb)
{
	int err;

	while (likely((err = xfrm4_output_one(skb)) == 0)) {
		nf_reset(skb);

		err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL,
			      skb->dst->dev, dst_output);
		if (unlikely(err != 1))
			break;

		if (!skb->dst->xfrm)
			return dst_output(skb);

		err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL,
			      skb->dst->dev, xfrm4_output_finish);
		if (unlikely(err != 1))
			break;
	}

	return err;
}

int xfrm4_output(struct sk_buff *skb)
{
	return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
		       xfrm4_output_finish);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* xfrm4_output.c - Common IPsec encapsulation code for IPv4.
	3	* Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License
	7	* as published by the Free Software Foundation; either version
	8	* 2 of the License, or (at your option) any later version.
	9	*/
	10
16a6677f	11	#include <linux/compiler.h>
1da177e4 LT	12	#include <linux/skbuff.h>
1da177e4 LT	13	#include <linux/spinlock.h>
16a6677f	14	#include <linux/netfilter_ipv4.h>
1da177e4 LT	15	#include <net/inet_ecn.h>
	16	#include <net/ip.h>
	17	#include <net/xfrm.h>
	18	#include <net/icmp.h>
	19
	20	/* Add encapsulation header.
	21	*
	22	* In transport mode, the IP header will be moved forward to make space
	23	* for the encapsulation header.
	24	*
	25	* In tunnel mode, the top IP header will be constructed per RFC 2401.
	26	* The following fields in it shall be filled in by x->type->output:
	27	* tot_len
	28	* check
	29	*
	30	* On exit, skb->h will be set to the start of the payload to be processed
	31	* by x->type->output and skb->nh will be set to the top IP header.
	32	*/
	33	static void xfrm4_encap(struct sk_buff *skb)
	34	{
	35	struct dst_entry *dst = skb->dst;
	36	struct xfrm_state *x = dst->xfrm;
	37	struct iphdr iph, top_iph;
dd87147e	38	int flags;
1da177e4 LT	39
	40	iph = skb->nh.iph;
	41	skb->h.ipiph = iph;
	42
	43	skb->nh.raw = skb_push(skb, x->props.header_len);
	44	top_iph = skb->nh.iph;
	45
	46	if (!x->props.mode) {
	47	skb->h.raw += iph->ihl*4;
	48	memmove(top_iph, iph, iph->ihl*4);
	49	return;
	50	}
	51
	52	top_iph->ihl = 5;
	53	top_iph->version = 4;
	54
	55	/* DS disclosed */
	56	top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
dd87147e HX	57
	58	flags = x->props.flags;
	59	if (flags & XFRM_STATE_NOECN)
1da177e4 LT	60	IP_ECN_clear(top_iph);
1da177e4 LT	61
dd87147e HX	62	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
dd87147e HX	63	0 : (iph->frag_off & htons(IP_DF));
1da177e4 LT	64	if (!top_iph->frag_off)
	65	__ip_select_ident(top_iph, dst, 0);
	66
	67	top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
	68
	69	top_iph->saddr = x->props.saddr.a4;
	70	top_iph->daddr = x->id.daddr.a4;
	71	top_iph->protocol = IPPROTO_IPIP;
	72
	73	memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
	74	}
	75
	76	static int xfrm4_tunnel_check_size(struct sk_buff *skb)
	77	{
	78	int mtu, ret = 0;
	79	struct dst_entry *dst;
	80	struct iphdr *iph = skb->nh.iph;
	81
	82	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
	83	goto out;
	84
	85	IPCB(skb)->flags \|= IPSKB_XFRM_TUNNEL_SIZE;
	86
	87	if (!(iph->frag_off & htons(IP_DF)) \|\| skb->local_df)
	88	goto out;
	89
	90	dst = skb->dst;
	91	mtu = dst_mtu(dst);
	92	if (skb->len > mtu) {
	93	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
	94	ret = -EMSGSIZE;
	95	}
	96	out:
	97	return ret;
	98	}
	99
16a6677f	100	static int xfrm4_output_one(struct sk_buff *skb)
1da177e4 LT	101	{
	102	struct dst_entry *dst = skb->dst;
	103	struct xfrm_state *x = dst->xfrm;
	104	int err;
	105
	106	if (skb->ip_summed == CHECKSUM_HW) {
	107	err = skb_checksum_help(skb, 0);
	108	if (err)
	109	goto error_nolock;
	110	}
	111
	112	if (x->props.mode) {
	113	err = xfrm4_tunnel_check_size(skb);
	114	if (err)
	115	goto error_nolock;
	116	}
	117
16a6677f PM	118	do {
	119	spin_lock_bh(&x->lock);
	120	err = xfrm_state_check(x, skb);
	121	if (err)
	122	goto error;
1da177e4	123
16a6677f	124	xfrm4_encap(skb);
1da177e4	125
16a6677f PM	126	err = x->type->output(x, skb);
	127	if (err)
	128	goto error;
1da177e4	129
16a6677f PM	130	x->curlft.bytes += skb->len;
16a6677f PM	131	x->curlft.packets++;
1da177e4	132
16a6677f	133	spin_unlock_bh(&x->lock);
1da177e4	134
16a6677f PM	135	if (!(skb->dst = dst_pop(dst))) {
	136	err = -EHOSTUNREACH;
	137	goto error_nolock;
	138	}
	139	dst = skb->dst;
	140	x = dst->xfrm;
	141	} while (x && !x->props.mode);
	142
3e3850e9	143	IPCB(skb)->flags \|= IPSKB_XFRM_TRANSFORMED;
16a6677f	144	err = 0;
1da177e4 LT	145
	146	out_exit:
	147	return err;
	148	error:
	149	spin_unlock_bh(&x->lock);
	150	error_nolock:
	151	kfree_skb(skb);
	152	goto out_exit;
	153	}
16a6677f	154
5c901daa	155	int xfrm4_output_finish(struct sk_buff *skb)
16a6677f PM	156	{
	157	int err;
	158
	159	while (likely((err = xfrm4_output_one(skb)) == 0)) {
	160	nf_reset(skb);
	161
	162	err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL,
	163	skb->dst->dev, dst_output);
	164	if (unlikely(err != 1))
	165	break;
	166
	167	if (!skb->dst->xfrm)
	168	return dst_output(skb);
	169
	170	err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL,
	171	skb->dst->dev, xfrm4_output_finish);
	172	if (unlikely(err != 1))
	173	break;
	174	}
	175
	176	return err;
	177	}
	178
	179	int xfrm4_output(struct sk_buff *skb)
	180	{
	181	return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
	182	xfrm4_output_finish);
	183	}