[linux.git] / net / ipv6 / ah6.c

/*
 * Copyright (C)2002 USAGI/WIDE Project
 * 
 * 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.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Authors
 *
 *	Mitsuru KANDA @USAGI       : IPv6 Support 
 * 	Kazunori MIYAZAWA @USAGI   :
 * 	Kunihiro Ishiguro <[email protected]>
 * 	
 * 	This file is derived from net/ipv4/ah.c.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/ah.h>
#include <linux/crypto.h>
#include <linux/pfkeyv2.h>
#include <linux/string.h>
#include <net/icmp.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/xfrm.h>
#include <asm/scatterlist.h>

static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
{
	u8 *opt = (u8 *)opthdr;
	int len = ipv6_optlen(opthdr);
	int off = 0;
	int optlen = 0;

	off += 2;
	len -= 2;

	while (len > 0) {

		switch (opt[off]) {

		case IPV6_TLV_PAD0:
			optlen = 1;
			break;
		default:
			if (len < 2) 
				goto bad;
			optlen = opt[off+1]+2;
			if (len < optlen)
				goto bad;
			if (opt[off] & 0x20)
				memset(&opt[off+2], 0, opt[off+1]);
			break;
		}

		off += optlen;
		len -= optlen;
	}
	if (len == 0)
		return 1;

bad:
	return 0;
}

/**
 *	ipv6_rearrange_rthdr - rearrange IPv6 routing header
 *	@iph: IPv6 header
 *	@rthdr: routing header
 *
 *	Rearrange the destination address in @iph and the addresses in @rthdr
 *	so that they appear in the order they will at the final destination.
 *	See Appendix A2 of RFC 2402 for details.
 */
static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
{
	int segments, segments_left;
	struct in6_addr *addrs;
	struct in6_addr final_addr;

	segments_left = rthdr->segments_left;
	if (segments_left == 0)
		return;
	rthdr->segments_left = 0; 

	/* The value of rthdr->hdrlen has been verified either by the system
	 * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
	 * packets.  So we can assume that it is even and that segments is
	 * greater than or equal to segments_left.
	 *
	 * For the same reason we can assume that this option is of type 0.
	 */
	segments = rthdr->hdrlen >> 1;

	addrs = ((struct rt0_hdr *)rthdr)->addr;
	ipv6_addr_copy(&final_addr, addrs + segments - 1);

	addrs += segments - segments_left;
	memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));

	ipv6_addr_copy(addrs, &iph->daddr);
	ipv6_addr_copy(&iph->daddr, &final_addr);
}

static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
{
	union {
		struct ipv6hdr *iph;
		struct ipv6_opt_hdr *opth;
		struct ipv6_rt_hdr *rth;
		char *raw;
	} exthdr = { .iph = iph };
	char *end = exthdr.raw + len;
	int nexthdr = iph->nexthdr;

	exthdr.iph++;

	while (exthdr.raw < end) {
		switch (nexthdr) {
		case NEXTHDR_HOP:
		case NEXTHDR_DEST:
			if (!zero_out_mutable_opts(exthdr.opth)) {
				LIMIT_NETDEBUG(
					KERN_WARNING "overrun %sopts\n",
					nexthdr == NEXTHDR_HOP ?
						"hop" : "dest");
				return -EINVAL;
			}
			break;

		case NEXTHDR_ROUTING:
			ipv6_rearrange_rthdr(iph, exthdr.rth);
			break;

		default :
			return 0;
		}

		nexthdr = exthdr.opth->nexthdr;
		exthdr.raw += ipv6_optlen(exthdr.opth);
	}

	return 0;
}

static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
{
	int err;
	int extlen;
	struct ipv6hdr *top_iph;
	struct ip_auth_hdr *ah;
	struct ah_data *ahp;
	u8 nexthdr;
	char tmp_base[8];
	struct {
		struct in6_addr daddr;
		char hdrs[0];
	} *tmp_ext;

	top_iph = (struct ipv6hdr *)skb->data;
	top_iph->payload_len = htons(skb->len - sizeof(*top_iph));

	nexthdr = *skb->nh.raw;
	*skb->nh.raw = IPPROTO_AH;

	/* When there are no extension headers, we only need to save the first
	 * 8 bytes of the base IP header.
	 */
	memcpy(tmp_base, top_iph, sizeof(tmp_base));

	tmp_ext = NULL;
	extlen = skb->h.raw - (unsigned char *)(top_iph + 1);
	if (extlen) {
		extlen += sizeof(*tmp_ext);
		tmp_ext = kmalloc(extlen, GFP_ATOMIC);
		if (!tmp_ext) {
			err = -ENOMEM;
			goto error;
		}
		memcpy(tmp_ext, &top_iph->daddr, extlen);
		err = ipv6_clear_mutable_options(top_iph,
						 extlen - sizeof(*tmp_ext) +
						 sizeof(*top_iph));
		if (err)
			goto error_free_iph;
	}

	ah = (struct ip_auth_hdr *)skb->h.raw;
	ah->nexthdr = nexthdr;

	top_iph->priority    = 0;
	top_iph->flow_lbl[0] = 0;
	top_iph->flow_lbl[1] = 0;
	top_iph->flow_lbl[2] = 0;
	top_iph->hop_limit   = 0;

	ahp = x->data;
	ah->hdrlen  = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + 
				   ahp->icv_trunc_len) >> 2) - 2;

	ah->reserved = 0;
	ah->spi = x->id.spi;
	ah->seq_no = htonl(++x->replay.oseq);
	ahp->icv(ahp, skb, ah->auth_data);

	err = 0;

	memcpy(top_iph, tmp_base, sizeof(tmp_base));
	if (tmp_ext) {
		memcpy(&top_iph->daddr, tmp_ext, extlen);
error_free_iph:
		kfree(tmp_ext);
	}

error:
	return err;
}

static int ah6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
{
	/*
	 * Before process AH
	 * [IPv6][Ext1][Ext2][AH][Dest][Payload]
	 * |<-------------->| hdr_len
	 *
	 * To erase AH:
	 * Keeping copy of cleared headers. After AH processing,
	 * Moving the pointer of skb->nh.raw by using skb_pull as long as AH
	 * header length. Then copy back the copy as long as hdr_len
	 * If destination header following AH exists, copy it into after [Ext2].
	 * 
	 * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
	 * There is offset of AH before IPv6 header after the process.
	 */

	struct ipv6_auth_hdr *ah;
	struct ah_data *ahp;
	unsigned char *tmp_hdr = NULL;
	u16 hdr_len;
	u16 ah_hlen;
	int nexthdr;

	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
		goto out;

	/* We are going to _remove_ AH header to keep sockets happy,
	 * so... Later this can change. */
	if (skb_cloned(skb) &&
	    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
		goto out;

	hdr_len = skb->data - skb->nh.raw;
	ah = (struct ipv6_auth_hdr*)skb->data;
	ahp = x->data;
	nexthdr = ah->nexthdr;
	ah_hlen = (ah->hdrlen + 2) << 2;

        if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) &&
            ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len))
                goto out;

	if (!pskb_may_pull(skb, ah_hlen))
		goto out;

	tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
	if (!tmp_hdr)
		goto out;
	memcpy(tmp_hdr, skb->nh.raw, hdr_len);
	if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len))
		goto out;
	skb->nh.ipv6h->priority    = 0;
	skb->nh.ipv6h->flow_lbl[0] = 0;
	skb->nh.ipv6h->flow_lbl[1] = 0;
	skb->nh.ipv6h->flow_lbl[2] = 0;
	skb->nh.ipv6h->hop_limit   = 0;

        {
		u8 auth_data[MAX_AH_AUTH_LEN];

		memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
		memset(ah->auth_data, 0, ahp->icv_trunc_len);
		skb_push(skb, skb->data - skb->nh.raw);
		ahp->icv(ahp, skb, ah->auth_data);
		if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
			LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n");
			x->stats.integrity_failed++;
			goto free_out;
		}
	}

	skb->nh.raw = skb_pull(skb, ah_hlen);
	memcpy(skb->nh.raw, tmp_hdr, hdr_len);
	skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
	skb_pull(skb, hdr_len);
	skb->h.raw = skb->data;


	kfree(tmp_hdr);

	return nexthdr;

free_out:
	kfree(tmp_hdr);
out:
	return -EINVAL;
}

static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 
                    int type, int code, int offset, __u32 info)
{
	struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
	struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
	struct xfrm_state *x;

	if (type != ICMPV6_DEST_UNREACH &&
	    type != ICMPV6_PKT_TOOBIG)
		return;

	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
	if (!x)
		return;

	NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/"
		 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
		 ntohl(ah->spi), NIP6(iph->daddr));

	xfrm_state_put(x);
}

static int ah6_init_state(struct xfrm_state *x)
{
	struct ah_data *ahp = NULL;
	struct xfrm_algo_desc *aalg_desc;

	if (!x->aalg)
		goto error;

	/* null auth can use a zero length key */
	if (x->aalg->alg_key_len > 512)
		goto error;

	if (x->encap)
		goto error;

	ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
	if (ahp == NULL)
		return -ENOMEM;

	memset(ahp, 0, sizeof(*ahp));

	ahp->key = x->aalg->alg_key;
	ahp->key_len = (x->aalg->alg_key_len+7)/8;
	ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
	if (!ahp->tfm)
		goto error;
	ahp->icv = ah_hmac_digest;
	
	/*
	 * Lookup the algorithm description maintained by xfrm_algo,
	 * verify crypto transform properties, and store information
	 * we need for AH processing.  This lookup cannot fail here
	 * after a successful crypto_alloc_tfm().
	 */
	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	BUG_ON(!aalg_desc);

	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
	    crypto_tfm_alg_digestsize(ahp->tfm)) {
		printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
		       x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
		       aalg_desc->uinfo.auth.icv_fullbits/8);
		goto error;
	}
	
	ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	
	BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
	
	ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
	if (!ahp->work_icv)
		goto error;
	
	x->props.header_len = XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len);
	if (x->props.mode)
		x->props.header_len += sizeof(struct ipv6hdr);
	x->data = ahp;

	return 0;

error:
	if (ahp) {
		kfree(ahp->work_icv);
		crypto_free_tfm(ahp->tfm);
		kfree(ahp);
	}
	return -EINVAL;
}

static void ah6_destroy(struct xfrm_state *x)
{
	struct ah_data *ahp = x->data;

	if (!ahp)
		return;

	kfree(ahp->work_icv);
	ahp->work_icv = NULL;
	crypto_free_tfm(ahp->tfm);
	ahp->tfm = NULL;
	kfree(ahp);
}

static struct xfrm_type ah6_type =
{
	.description	= "AH6",
	.owner		= THIS_MODULE,
	.proto	     	= IPPROTO_AH,
	.init_state	= ah6_init_state,
	.destructor	= ah6_destroy,
	.input		= ah6_input,
	.output		= ah6_output
};

static struct inet6_protocol ah6_protocol = {
	.handler	=	xfrm6_rcv,
	.err_handler	=	ah6_err,
	.flags		=	INET6_PROTO_NOPOLICY,
};

static int __init ah6_init(void)
{
	if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
		printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
		return -EAGAIN;
	}

	if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
		printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
		xfrm_unregister_type(&ah6_type, AF_INET6);
		return -EAGAIN;
	}

	return 0;
}

static void __exit ah6_fini(void)
{
	if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
		printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");

	if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
		printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");

}

module_init(ah6_init);
module_exit(ah6_fini);

MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C)2002 USAGI/WIDE Project
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2 of the License, or
	7	* (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, write to the Free Software
	16	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	17	*
	18	* Authors
	19	*
	20	* Mitsuru KANDA @USAGI : IPv6 Support
	21	* Kazunori MIYAZAWA @USAGI :
	22	* Kunihiro Ishiguro <[email protected]>
	23	*
	24	* This file is derived from net/ipv4/ah.c.
	25	*/
	26
	27	#include <linux/config.h>
	28	#include <linux/module.h>
	29	#include <net/ip.h>
	30	#include <net/ah.h>
	31	#include <linux/crypto.h>
	32	#include <linux/pfkeyv2.h>
	33	#include <linux/string.h>
	34	#include <net/icmp.h>
	35	#include <net/ipv6.h>
14c85021	36	#include <net/protocol.h>
1da177e4 LT	37	#include <net/xfrm.h>
	38	#include <asm/scatterlist.h>
	39
	40	static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
	41	{
	42	u8 opt = (u8 )opthdr;
	43	int len = ipv6_optlen(opthdr);
	44	int off = 0;
	45	int optlen = 0;
	46
	47	off += 2;
	48	len -= 2;
	49
	50	while (len > 0) {
	51
	52	switch (opt[off]) {
	53
	54	case IPV6_TLV_PAD0:
	55	optlen = 1;
	56	break;
	57	default:
	58	if (len < 2)
	59	goto bad;
	60	optlen = opt[off+1]+2;
	61	if (len < optlen)
	62	goto bad;
	63	if (opt[off] & 0x20)
	64	memset(&opt[off+2], 0, opt[off+1]);
	65	break;
	66	}
	67
	68	off += optlen;
	69	len -= optlen;
	70	}
	71	if (len == 0)
	72	return 1;
	73
	74	bad:
	75	return 0;
	76	}
	77
	78	/**
	79	* ipv6_rearrange_rthdr - rearrange IPv6 routing header
	80	* @iph: IPv6 header
	81	* @rthdr: routing header
	82	*
	83	* Rearrange the destination address in @iph and the addresses in @rthdr
	84	* so that they appear in the order they will at the final destination.
	85	* See Appendix A2 of RFC 2402 for details.
	86	*/
	87	static void ipv6_rearrange_rthdr(struct ipv6hdr iph, struct ipv6_rt_hdr rthdr)
	88	{
	89	int segments, segments_left;
	90	struct in6_addr *addrs;
	91	struct in6_addr final_addr;
	92
	93	segments_left = rthdr->segments_left;
	94	if (segments_left == 0)
	95	return;
	96	rthdr->segments_left = 0;
	97
	98	/* The value of rthdr->hdrlen has been verified either by the system
	99	* call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
	100	* packets. So we can assume that it is even and that segments is
101	* greater than or equal to segments_left.
102	*
103	* For the same reason we can assume that this option is of type 0.
104	*/
105	segments = rthdr->hdrlen >> 1;
106
107	addrs = ((struct rt0_hdr *)rthdr)->addr;
108	ipv6_addr_copy(&final_addr, addrs + segments - 1);
109
110	addrs += segments - segments_left;
111	memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
112
113	ipv6_addr_copy(addrs, &iph->daddr);
114	ipv6_addr_copy(&iph->daddr, &final_addr);
115	}
116
117	static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
118	{
119	union {
120	struct ipv6hdr *iph;
121	struct ipv6_opt_hdr *opth;
122	struct ipv6_rt_hdr *rth;
123	char *raw;
124	} exthdr = { .iph = iph };
125	char *end = exthdr.raw + len;
126	int nexthdr = iph->nexthdr;
127
128	exthdr.iph++;
129
130	while (exthdr.raw < end) {
131	switch (nexthdr) {
132	case NEXTHDR_HOP:
133	case NEXTHDR_DEST:
134	if (!zero_out_mutable_opts(exthdr.opth)) {
64ce2073	135	LIMIT_NETDEBUG(
1da177e4 LT	136	KERN_WARNING "overrun %sopts\n",
1da177e4 LT	137	nexthdr == NEXTHDR_HOP ?
64ce2073	138	"hop" : "dest");
1da177e4 LT	139	return -EINVAL;
	140	}
	141	break;
	142
	143	case NEXTHDR_ROUTING:
	144	ipv6_rearrange_rthdr(iph, exthdr.rth);
	145	break;
	146
	147	default :
	148	return 0;
	149	}
	150
	151	nexthdr = exthdr.opth->nexthdr;
	152	exthdr.raw += ipv6_optlen(exthdr.opth);
	153	}
	154
	155	return 0;
	156	}
	157
	158	static int ah6_output(struct xfrm_state x, struct sk_buff skb)
	159	{
	160	int err;
	161	int extlen;
	162	struct ipv6hdr *top_iph;
	163	struct ip_auth_hdr *ah;
	164	struct ah_data *ahp;
	165	u8 nexthdr;
	166	char tmp_base[8];
	167	struct {
	168	struct in6_addr daddr;
	169	char hdrs[0];
	170	} *tmp_ext;
	171
	172	top_iph = (struct ipv6hdr *)skb->data;
	173	top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
	174
	175	nexthdr = *skb->nh.raw;
	176	*skb->nh.raw = IPPROTO_AH;
	177
	178	/* When there are no extension headers, we only need to save the first
	179	* 8 bytes of the base IP header.
	180	*/
	181	memcpy(tmp_base, top_iph, sizeof(tmp_base));
	182
	183	tmp_ext = NULL;
	184	extlen = skb->h.raw - (unsigned char *)(top_iph + 1);
	185	if (extlen) {
	186	extlen += sizeof(*tmp_ext);
	187	tmp_ext = kmalloc(extlen, GFP_ATOMIC);
	188	if (!tmp_ext) {
	189	err = -ENOMEM;
	190	goto error;
	191	}
	192	memcpy(tmp_ext, &top_iph->daddr, extlen);
	193	err = ipv6_clear_mutable_options(top_iph,
	194	extlen - sizeof(*tmp_ext) +
	195	sizeof(*top_iph));
	196	if (err)
	197	goto error_free_iph;
	198	}
	199
	200	ah = (struct ip_auth_hdr *)skb->h.raw;
	201	ah->nexthdr = nexthdr;
	202
203	top_iph->priority = 0;
204	top_iph->flow_lbl[0] = 0;
205	top_iph->flow_lbl[1] = 0;
206	top_iph->flow_lbl[2] = 0;
207	top_iph->hop_limit = 0;
208
209	ahp = x->data;
210	ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) +
211	ahp->icv_trunc_len) >> 2) - 2;
212
213	ah->reserved = 0;
214	ah->spi = x->id.spi;
215	ah->seq_no = htonl(++x->replay.oseq);
216	ahp->icv(ahp, skb, ah->auth_data);
217
218	err = 0;
219
220	memcpy(top_iph, tmp_base, sizeof(tmp_base));
221	if (tmp_ext) {
222	memcpy(&top_iph->daddr, tmp_ext, extlen);
223	error_free_iph:
224	kfree(tmp_ext);
225	}
226
227	error:
228	return err;
229	}
230
231	static int ah6_input(struct xfrm_state x, struct xfrm_decap_state decap, struct sk_buff *skb)
232	{
233	/*
234	* Before process AH
235	* [IPv6][Ext1][Ext2][AH][Dest][Payload]
236	* \|<-------------->\| hdr_len
237	*
238	* To erase AH:
239	* Keeping copy of cleared headers. After AH processing,
240	* Moving the pointer of skb->nh.raw by using skb_pull as long as AH
241	* header length. Then copy back the copy as long as hdr_len
242	* If destination header following AH exists, copy it into after [Ext2].
243	*
244	* \|<>\|[IPv6][Ext1][Ext2][Dest][Payload]
245	* There is offset of AH before IPv6 header after the process.
246	*/
247
248	struct ipv6_auth_hdr *ah;
249	struct ah_data *ahp;
250	unsigned char *tmp_hdr = NULL;
251	u16 hdr_len;
252	u16 ah_hlen;
253	int nexthdr;
254
255	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
256	goto out;
257
258	/* We are going to _remove_ AH header to keep sockets happy,
259	* so... Later this can change. */
260	if (skb_cloned(skb) &&
261	pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
262	goto out;
263
264	hdr_len = skb->data - skb->nh.raw;
265	ah = (struct ipv6_auth_hdr*)skb->data;
266	ahp = x->data;
267	nexthdr = ah->nexthdr;
268	ah_hlen = (ah->hdrlen + 2) << 2;
269
270	if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) &&
271	ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len))
272	goto out;
273
274	if (!pskb_may_pull(skb, ah_hlen))
275	goto out;
276
277	tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
278	if (!tmp_hdr)
279	goto out;
280	memcpy(tmp_hdr, skb->nh.raw, hdr_len);
281	if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len))
282	goto out;
283	skb->nh.ipv6h->priority = 0;
284	skb->nh.ipv6h->flow_lbl[0] = 0;
285	skb->nh.ipv6h->flow_lbl[1] = 0;
286	skb->nh.ipv6h->flow_lbl[2] = 0;
287	skb->nh.ipv6h->hop_limit = 0;
288
289	{
290	u8 auth_data[MAX_AH_AUTH_LEN];
291
292	memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
293	memset(ah->auth_data, 0, ahp->icv_trunc_len);
294	skb_push(skb, skb->data - skb->nh.raw);
295	ahp->icv(ahp, skb, ah->auth_data);
296	if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
64ce2073	297	LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n");
1da177e4 LT	298	x->stats.integrity_failed++;
	299	goto free_out;
	300	}
	301	}
	302
	303	skb->nh.raw = skb_pull(skb, ah_hlen);
	304	memcpy(skb->nh.raw, tmp_hdr, hdr_len);
	305	skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
	306	skb_pull(skb, hdr_len);
	307	skb->h.raw = skb->data;
	308
	309
	310	kfree(tmp_hdr);
	311
	312	return nexthdr;
	313
	314	free_out:
	315	kfree(tmp_hdr);
	316	out:
	317	return -EINVAL;
	318	}
	319
	320	static void ah6_err(struct sk_buff skb, struct inet6_skb_parm opt,
	321	int type, int code, int offset, __u32 info)
	322	{
	323	struct ipv6hdr iph = (struct ipv6hdr)skb->data;
	324	struct ip_auth_hdr ah = (struct ip_auth_hdr)(skb->data+offset);
	325	struct xfrm_state *x;
	326
	327	if (type != ICMPV6_DEST_UNREACH &&
	328	type != ICMPV6_PKT_TOOBIG)
	329	return;
	330
	331	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
	332	if (!x)
	333	return;
	334
64ce2073 PM	335	NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/"
	336	"%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
	337	ntohl(ah->spi), NIP6(iph->daddr));
1da177e4 LT	338
	339	xfrm_state_put(x);
	340	}
	341
72cb6962	342	static int ah6_init_state(struct xfrm_state *x)
1da177e4 LT	343	{
	344	struct ah_data *ahp = NULL;
	345	struct xfrm_algo_desc *aalg_desc;
	346
	347	if (!x->aalg)
	348	goto error;
	349
	350	/* null auth can use a zero length key */
	351	if (x->aalg->alg_key_len > 512)
	352	goto error;
	353
	354	if (x->encap)
	355	goto error;
	356
	357	ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
	358	if (ahp == NULL)
	359	return -ENOMEM;
	360
	361	memset(ahp, 0, sizeof(*ahp));
	362
	363	ahp->key = x->aalg->alg_key;
	364	ahp->key_len = (x->aalg->alg_key_len+7)/8;
	365	ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
	366	if (!ahp->tfm)
	367	goto error;
	368	ahp->icv = ah_hmac_digest;
	369
	370	/*
	371	* Lookup the algorithm description maintained by xfrm_algo,
	372	* verify crypto transform properties, and store information
	373	* we need for AH processing. This lookup cannot fail here
	374	* after a successful crypto_alloc_tfm().
	375	*/
	376	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	377	BUG_ON(!aalg_desc);
	378
	379	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
	380	crypto_tfm_alg_digestsize(ahp->tfm)) {
	381	printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
	382	x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
	383	aalg_desc->uinfo.auth.icv_fullbits/8);
	384	goto error;
	385	}
	386
	387	ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	388	ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	389
	390	BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
	391
	392	ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
	393	if (!ahp->work_icv)
	394	goto error;
	395
	396	x->props.header_len = XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len);
	397	if (x->props.mode)
	398	x->props.header_len += sizeof(struct ipv6hdr);
	399	x->data = ahp;
	400
	401	return 0;
	402
	403	error:
	404	if (ahp) {
573dbd95 JJ	405	kfree(ahp->work_icv);
573dbd95 JJ	406	crypto_free_tfm(ahp->tfm);
1da177e4 LT	407	kfree(ahp);
	408	}
	409	return -EINVAL;
	410	}
	411
	412	static void ah6_destroy(struct xfrm_state *x)
	413	{
	414	struct ah_data *ahp = x->data;
	415
	416	if (!ahp)
	417	return;
	418
573dbd95 JJ	419	kfree(ahp->work_icv);
	420	ahp->work_icv = NULL;
	421	crypto_free_tfm(ahp->tfm);
	422	ahp->tfm = NULL;
1da177e4 LT	423	kfree(ahp);
	424	}
	425
	426	static struct xfrm_type ah6_type =
	427	{
	428	.description = "AH6",
	429	.owner = THIS_MODULE,
	430	.proto = IPPROTO_AH,
	431	.init_state = ah6_init_state,
	432	.destructor = ah6_destroy,
	433	.input = ah6_input,
	434	.output = ah6_output
	435	};
	436
	437	static struct inet6_protocol ah6_protocol = {
	438	.handler = xfrm6_rcv,
	439	.err_handler = ah6_err,
	440	.flags = INET6_PROTO_NOPOLICY,
	441	};
	442
	443	static int __init ah6_init(void)
	444	{
	445	if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
	446	printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
	447	return -EAGAIN;
	448	}
	449
	450	if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
	451	printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
	452	xfrm_unregister_type(&ah6_type, AF_INET6);
	453	return -EAGAIN;
	454	}
	455
	456	return 0;
	457	}
	458
	459	static void __exit ah6_fini(void)
	460	{
	461	if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
	462	printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");
	463
	464	if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
	465	printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");
	466
	467	}
	468
	469	module_init(ah6_init);
	470	module_exit(ah6_fini);
	471
	472	MODULE_LICENSE("GPL");