[linux-2.6-block.git] / net / ipv4 / esp4.c

#include <linux/err.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/esp.h>
#include <asm/scatterlist.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/pfkeyv2.h>
#include <linux/random.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <net/udp.h>

static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
{
	int err;
	struct iphdr *top_iph;
	struct ip_esp_hdr *esph;
	struct crypto_blkcipher *tfm;
	struct blkcipher_desc desc;
	struct esp_data *esp;
	struct sk_buff *trailer;
	int blksize;
	int clen;
	int alen;
	int nfrags;

	/* Strip IP+ESP header. */
	__skb_pull(skb, skb->h.raw - skb->data);
	/* Now skb is pure payload to encrypt */

	err = -ENOMEM;

	/* Round to block size */
	clen = skb->len;

	esp = x->data;
	alen = esp->auth.icv_trunc_len;
	tfm = esp->conf.tfm;
	desc.tfm = tfm;
	desc.flags = 0;
	blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
	clen = ALIGN(clen + 2, blksize);
	if (esp->conf.padlen)
		clen = ALIGN(clen, esp->conf.padlen);

	if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
		goto error;

	/* Fill padding... */
	do {
		int i;
		for (i=0; i<clen-skb->len - 2; i++)
			*(u8*)(trailer->tail + i) = i+1;
	} while (0);
	*(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
	pskb_put(skb, trailer, clen - skb->len);

	__skb_push(skb, skb->data - skb->nh.raw);
	top_iph = skb->nh.iph;
	esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4);
	top_iph->tot_len = htons(skb->len + alen);
	*(u8*)(trailer->tail - 1) = top_iph->protocol;

	/* this is non-NULL only with UDP Encapsulation */
	if (x->encap) {
		struct xfrm_encap_tmpl *encap = x->encap;
		struct udphdr *uh;
		u32 *udpdata32;

		uh = (struct udphdr *)esph;
		uh->source = encap->encap_sport;
		uh->dest = encap->encap_dport;
		uh->len = htons(skb->len + alen - top_iph->ihl*4);
		uh->check = 0;

		switch (encap->encap_type) {
		default:
		case UDP_ENCAP_ESPINUDP:
			esph = (struct ip_esp_hdr *)(uh + 1);
			break;
		case UDP_ENCAP_ESPINUDP_NON_IKE:
			udpdata32 = (u32 *)(uh + 1);
			udpdata32[0] = udpdata32[1] = 0;
			esph = (struct ip_esp_hdr *)(udpdata32 + 2);
			break;
		}

		top_iph->protocol = IPPROTO_UDP;
	} else
		top_iph->protocol = IPPROTO_ESP;

	esph->spi = x->id.spi;
	esph->seq_no = htonl(++x->replay.oseq);
	xfrm_aevent_doreplay(x);

	if (esp->conf.ivlen)
		crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);

	do {
		struct scatterlist *sg = &esp->sgbuf[0];

		if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
			sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
			if (!sg)
				goto error;
		}
		skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
		err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
		if (unlikely(sg != &esp->sgbuf[0]))
			kfree(sg);
	} while (0);

	if (unlikely(err))
		goto error;

	if (esp->conf.ivlen) {
		memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
		crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
	}

	if (esp->auth.icv_full_len) {
		err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
				     sizeof(*esph) + esp->conf.ivlen + clen);
		memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
	}

	ip_send_check(top_iph);

error:
	return err;
}

/*
 * Note: detecting truncated vs. non-truncated authentication data is very
 * expensive, so we only support truncated data, which is the recommended
 * and common case.
 */
static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
{
	struct iphdr *iph;
	struct ip_esp_hdr *esph;
	struct esp_data *esp = x->data;
	struct crypto_blkcipher *tfm = esp->conf.tfm;
	struct blkcipher_desc desc = { .tfm = tfm };
	struct sk_buff *trailer;
	int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
	int alen = esp->auth.icv_trunc_len;
	int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
	int nfrags;
	int ihl;
	u8 nexthdr[2];
	struct scatterlist *sg;
	int padlen;
	int err;

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

	if (elen <= 0 || (elen & (blksize-1)))
		goto out;

	/* If integrity check is required, do this. */
	if (esp->auth.icv_full_len) {
		u8 sum[alen];

		err = esp_mac_digest(esp, skb, 0, skb->len - alen);
		if (err)
			goto out;

		if (skb_copy_bits(skb, skb->len - alen, sum, alen))
			BUG();

		if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
			x->stats.integrity_failed++;
			goto out;
		}
	}

	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
		goto out;

	skb->ip_summed = CHECKSUM_NONE;

	esph = (struct ip_esp_hdr*)skb->data;

	/* Get ivec. This can be wrong, check against another impls. */
	if (esp->conf.ivlen)
		crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);

	sg = &esp->sgbuf[0];

	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
		sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
		if (!sg)
			goto out;
	}
	skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
	err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
	if (unlikely(sg != &esp->sgbuf[0]))
		kfree(sg);
	if (unlikely(err))
		return err;

	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
		BUG();

	padlen = nexthdr[0];
	if (padlen+2 >= elen)
		goto out;

	/* ... check padding bits here. Silly. :-) */ 

	iph = skb->nh.iph;
	ihl = iph->ihl * 4;

	if (x->encap) {
		struct xfrm_encap_tmpl *encap = x->encap;
		struct udphdr *uh = (void *)(skb->nh.raw + ihl);

		/*
		 * 1) if the NAT-T peer's IP or port changed then
		 *    advertize the change to the keying daemon.
		 *    This is an inbound SA, so just compare
		 *    SRC ports.
		 */
		if (iph->saddr != x->props.saddr.a4 ||
		    uh->source != encap->encap_sport) {
			xfrm_address_t ipaddr;

			ipaddr.a4 = iph->saddr;
			km_new_mapping(x, &ipaddr, uh->source);
				
			/* XXX: perhaps add an extra
			 * policy check here, to see
			 * if we should allow or
			 * reject a packet from a
			 * different source
			 * address/port.
			 */
		}
	
		/*
		 * 2) ignore UDP/TCP checksums in case
		 *    of NAT-T in Transport Mode, or
		 *    perform other post-processing fixes
		 *    as per draft-ietf-ipsec-udp-encaps-06,
		 *    section 3.1.2
		 */
		if (x->props.mode == XFRM_MODE_TRANSPORT)
			skb->ip_summed = CHECKSUM_UNNECESSARY;
	}

	iph->protocol = nexthdr[1];
	pskb_trim(skb, skb->len - alen - padlen - 2);
	skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl;

	return 0;

out:
	return -EINVAL;
}

static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
{
	struct esp_data *esp = x->data;
	u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);

	if (x->props.mode == XFRM_MODE_TUNNEL) {
		mtu = ALIGN(mtu + 2, blksize);
	} else {
		/* The worst case. */
		mtu = ALIGN(mtu + 2, 4) + blksize - 4;
	}
	if (esp->conf.padlen)
		mtu = ALIGN(mtu, esp->conf.padlen);

	return mtu + x->props.header_len + esp->auth.icv_trunc_len;
}

static void esp4_err(struct sk_buff *skb, u32 info)
{
	struct iphdr *iph = (struct iphdr*)skb->data;
	struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2));
	struct xfrm_state *x;

	if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
	    skb->h.icmph->code != ICMP_FRAG_NEEDED)
		return;

	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	if (!x)
		return;
	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
		 ntohl(esph->spi), ntohl(iph->daddr));
	xfrm_state_put(x);
}

static void esp_destroy(struct xfrm_state *x)
{
	struct esp_data *esp = x->data;

	if (!esp)
		return;

	crypto_free_blkcipher(esp->conf.tfm);
	esp->conf.tfm = NULL;
	kfree(esp->conf.ivec);
	esp->conf.ivec = NULL;
	crypto_free_hash(esp->auth.tfm);
	esp->auth.tfm = NULL;
	kfree(esp->auth.work_icv);
	esp->auth.work_icv = NULL;
	kfree(esp);
}

static int esp_init_state(struct xfrm_state *x)
{
	struct esp_data *esp = NULL;
	struct crypto_blkcipher *tfm;

	/* null auth and encryption can have zero length keys */
	if (x->aalg) {
		if (x->aalg->alg_key_len > 512)
			goto error;
	}
	if (x->ealg == NULL)
		goto error;

	esp = kzalloc(sizeof(*esp), GFP_KERNEL);
	if (esp == NULL)
		return -ENOMEM;

	if (x->aalg) {
		struct xfrm_algo_desc *aalg_desc;
		struct crypto_hash *hash;

		esp->auth.key = x->aalg->alg_key;
		esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
		hash = crypto_alloc_hash(x->aalg->alg_name, 0,
					 CRYPTO_ALG_ASYNC);
		if (IS_ERR(hash))
			goto error;

		esp->auth.tfm = hash;
		if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
			goto error;

		aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
		BUG_ON(!aalg_desc);

		if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
		    crypto_hash_digestsize(hash)) {
			NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
				 x->aalg->alg_name,
				 crypto_hash_digestsize(hash),
				 aalg_desc->uinfo.auth.icv_fullbits/8);
			goto error;
		}

		esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
		esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;

		esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
		if (!esp->auth.work_icv)
			goto error;
	}
	esp->conf.key = x->ealg->alg_key;
	esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
	tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(tfm))
		goto error;
	esp->conf.tfm = tfm;
	esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
	esp->conf.padlen = 0;
	if (esp->conf.ivlen) {
		esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
		if (unlikely(esp->conf.ivec == NULL))
			goto error;
		get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	}
	if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
		goto error;
	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
	if (x->props.mode == XFRM_MODE_TUNNEL)
		x->props.header_len += sizeof(struct iphdr);
	if (x->encap) {
		struct xfrm_encap_tmpl *encap = x->encap;

		switch (encap->encap_type) {
		default:
			goto error;
		case UDP_ENCAP_ESPINUDP:
			x->props.header_len += sizeof(struct udphdr);
			break;
		case UDP_ENCAP_ESPINUDP_NON_IKE:
			x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
			break;
		}
	}
	x->data = esp;
	x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
	return 0;

error:
	x->data = esp;
	esp_destroy(x);
	x->data = NULL;
	return -EINVAL;
}

static struct xfrm_type esp_type =
{
	.description	= "ESP4",
	.owner		= THIS_MODULE,
	.proto	     	= IPPROTO_ESP,
	.init_state	= esp_init_state,
	.destructor	= esp_destroy,
	.get_max_size	= esp4_get_max_size,
	.input		= esp_input,
	.output		= esp_output
};

static struct net_protocol esp4_protocol = {
	.handler	=	xfrm4_rcv,
	.err_handler	=	esp4_err,
	.no_policy	=	1,
};

static int __init esp4_init(void)
{
	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
		printk(KERN_INFO "ip esp init: can't add xfrm type\n");
		return -EAGAIN;
	}
	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
		printk(KERN_INFO "ip esp init: can't add protocol\n");
		xfrm_unregister_type(&esp_type, AF_INET);
		return -EAGAIN;
	}
	return 0;
}

static void __exit esp4_fini(void)
{
	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
		printk(KERN_INFO "ip esp close: can't remove protocol\n");
	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
		printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
}

module_init(esp4_init);
module_exit(esp4_fini);
MODULE_LICENSE("GPL");
Commit	Line	Data
6b7326c8	1	#include <linux/err.h>
1da177e4 LT	2	#include <linux/module.h>
	3	#include <net/ip.h>
	4	#include <net/xfrm.h>
	5	#include <net/esp.h>
	6	#include <asm/scatterlist.h>
	7	#include <linux/crypto.h>
a02a6422	8	#include <linux/kernel.h>
1da177e4 LT	9	#include <linux/pfkeyv2.h>
	10	#include <linux/random.h>
	11	#include <net/icmp.h>
14c85021	12	#include <net/protocol.h>
1da177e4 LT	13	#include <net/udp.h>
1da177e4 LT	14
1da177e4 LT	15	static int esp_output(struct xfrm_state x, struct sk_buff skb)
	16	{
	17	int err;
	18	struct iphdr *top_iph;
	19	struct ip_esp_hdr *esph;
6b7326c8 HX	20	struct crypto_blkcipher *tfm;
6b7326c8 HX	21	struct blkcipher_desc desc;
1da177e4 LT	22	struct esp_data *esp;
	23	struct sk_buff *trailer;
	24	int blksize;
	25	int clen;
	26	int alen;
	27	int nfrags;
	28
	29	/* Strip IP+ESP header. */
	30	__skb_pull(skb, skb->h.raw - skb->data);
	31	/* Now skb is pure payload to encrypt */
	32
	33	err = -ENOMEM;
	34
	35	/* Round to block size */
	36	clen = skb->len;
	37
	38	esp = x->data;
	39	alen = esp->auth.icv_trunc_len;
	40	tfm = esp->conf.tfm;
6b7326c8 HX	41	desc.tfm = tfm;
	42	desc.flags = 0;
	43	blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
a02a6422	44	clen = ALIGN(clen + 2, blksize);
1da177e4	45	if (esp->conf.padlen)
a02a6422	46	clen = ALIGN(clen, esp->conf.padlen);
1da177e4 LT	47
	48	if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
	49	goto error;
	50
	51	/* Fill padding... */
	52	do {
	53	int i;
	54	for (i=0; i<clen-skb->len - 2; i++)
	55	(u8)(trailer->tail + i) = i+1;
	56	} while (0);
	57	(u8)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
	58	pskb_put(skb, trailer, clen - skb->len);
	59
	60	__skb_push(skb, skb->data - skb->nh.raw);
	61	top_iph = skb->nh.iph;
	62	esph = (struct ip_esp_hdr )(skb->nh.raw + top_iph->ihl4);
	63	top_iph->tot_len = htons(skb->len + alen);
	64	(u8)(trailer->tail - 1) = top_iph->protocol;
	65
	66	/* this is non-NULL only with UDP Encapsulation */
	67	if (x->encap) {
	68	struct xfrm_encap_tmpl *encap = x->encap;
	69	struct udphdr *uh;
	70	u32 *udpdata32;
	71
	72	uh = (struct udphdr *)esph;
	73	uh->source = encap->encap_sport;
	74	uh->dest = encap->encap_dport;
	75	uh->len = htons(skb->len + alen - top_iph->ihl*4);
	76	uh->check = 0;
	77
	78	switch (encap->encap_type) {
	79	default:
	80	case UDP_ENCAP_ESPINUDP:
	81	esph = (struct ip_esp_hdr *)(uh + 1);
	82	break;
	83	case UDP_ENCAP_ESPINUDP_NON_IKE:
	84	udpdata32 = (u32 *)(uh + 1);
	85	udpdata32[0] = udpdata32[1] = 0;
	86	esph = (struct ip_esp_hdr *)(udpdata32 + 2);
	87	break;
	88	}
	89
	90	top_iph->protocol = IPPROTO_UDP;
	91	} else
	92	top_iph->protocol = IPPROTO_ESP;
	93
	94	esph->spi = x->id.spi;
	95	esph->seq_no = htonl(++x->replay.oseq);
9500e8a8	96	xfrm_aevent_doreplay(x);
1da177e4 LT	97
1da177e4 LT	98	if (esp->conf.ivlen)
6b7326c8	99	crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
1da177e4 LT	100
	101	do {
	102	struct scatterlist *sg = &esp->sgbuf[0];
	103
	104	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	105	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	106	if (!sg)
	107	goto error;
	108	}
	109	skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
6b7326c8	110	err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
1da177e4 LT	111	if (unlikely(sg != &esp->sgbuf[0]))
	112	kfree(sg);
	113	} while (0);
	114
6b7326c8 HX	115	if (unlikely(err))
	116	goto error;
	117
1da177e4	118	if (esp->conf.ivlen) {
6b7326c8 HX	119	memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
6b7326c8 HX	120	crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
1da177e4 LT	121	}
	122
	123	if (esp->auth.icv_full_len) {
07d4ee58 HX	124	err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
	125	sizeof(*esph) + esp->conf.ivlen + clen);
	126	memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
1da177e4 LT	127	}
	128
	129	ip_send_check(top_iph);
	130
1da177e4 LT	131	error:
	132	return err;
	133	}
	134
	135	/*
	136	* Note: detecting truncated vs. non-truncated authentication data is very
	137	* expensive, so we only support truncated data, which is the recommended
	138	* and common case.
	139	*/
e695633e	140	static int esp_input(struct xfrm_state x, struct sk_buff skb)
1da177e4 LT	141	{
	142	struct iphdr *iph;
	143	struct ip_esp_hdr *esph;
	144	struct esp_data *esp = x->data;
6b7326c8 HX	145	struct crypto_blkcipher *tfm = esp->conf.tfm;
6b7326c8 HX	146	struct blkcipher_desc desc = { .tfm = tfm };
1da177e4	147	struct sk_buff *trailer;
6b7326c8	148	int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
1da177e4 LT	149	int alen = esp->auth.icv_trunc_len;
	150	int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
	151	int nfrags;
31a4ab93	152	int ihl;
4bf05ece HX	153	u8 nexthdr[2];
4bf05ece HX	154	struct scatterlist *sg;
4bf05ece	155	int padlen;
6b7326c8	156	int err;
1da177e4 LT	157
	158	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
	159	goto out;
	160
	161	if (elen <= 0 \|\| (elen & (blksize-1)))
	162	goto out;
	163
	164	/* If integrity check is required, do this. */
	165	if (esp->auth.icv_full_len) {
07d4ee58	166	u8 sum[alen];
1da177e4	167
07d4ee58 HX	168	err = esp_mac_digest(esp, skb, 0, skb->len - alen);
	169	if (err)
	170	goto out;
	171
	172	if (skb_copy_bits(skb, skb->len - alen, sum, alen))
1da177e4 LT	173	BUG();
1da177e4 LT	174
07d4ee58	175	if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
1da177e4 LT	176	x->stats.integrity_failed++;
	177	goto out;
	178	}
	179	}
	180
	181	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
	182	goto out;
	183
	184	skb->ip_summed = CHECKSUM_NONE;
	185
	186	esph = (struct ip_esp_hdr*)skb->data;
1da177e4 LT	187
	188	/* Get ivec. This can be wrong, check against another impls. */
	189	if (esp->conf.ivlen)
6b7326c8	190	crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
1da177e4	191
4bf05ece	192	sg = &esp->sgbuf[0];
1da177e4	193
4bf05ece HX	194	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	195	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	196	if (!sg)
	197	goto out;
	198	}
	199	skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
6b7326c8	200	err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
4bf05ece HX	201	if (unlikely(sg != &esp->sgbuf[0]))
4bf05ece HX	202	kfree(sg);
6b7326c8 HX	203	if (unlikely(err))
6b7326c8 HX	204	return err;
1da177e4	205
4bf05ece HX	206	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
4bf05ece HX	207	BUG();
1da177e4	208
4bf05ece HX	209	padlen = nexthdr[0];
	210	if (padlen+2 >= elen)
	211	goto out;
1da177e4	212
4bf05ece	213	/* ... check padding bits here. Silly. :-) */
1da177e4	214
31a4ab93 HX	215	iph = skb->nh.iph;
	216	ihl = iph->ihl * 4;
	217
752c1f4c HX	218	if (x->encap) {
752c1f4c HX	219	struct xfrm_encap_tmpl *encap = x->encap;
31a4ab93	220	struct udphdr uh = (void )(skb->nh.raw + ihl);
752c1f4c HX	221
	222	/*
	223	* 1) if the NAT-T peer's IP or port changed then
	224	* advertize the change to the keying daemon.
	225	* This is an inbound SA, so just compare
	226	* SRC ports.
	227	*/
	228	if (iph->saddr != x->props.saddr.a4 \|\|
	229	uh->source != encap->encap_sport) {
	230	xfrm_address_t ipaddr;
	231
	232	ipaddr.a4 = iph->saddr;
	233	km_new_mapping(x, &ipaddr, uh->source);
	234
	235	/* XXX: perhaps add an extra
	236	* policy check here, to see
	237	* if we should allow or
	238	* reject a packet from a
	239	* different source
	240	* address/port.
	241	*/
1da177e4	242	}
752c1f4c HX	243
	244	/*
	245	* 2) ignore UDP/TCP checksums in case
	246	* of NAT-T in Transport Mode, or
	247	* perform other post-processing fixes
	248	* as per draft-ietf-ipsec-udp-encaps-06,
	249	* section 3.1.2
	250	*/
7e49e6de	251	if (x->props.mode == XFRM_MODE_TRANSPORT)
752c1f4c	252	skb->ip_summed = CHECKSUM_UNNECESSARY;
1da177e4 LT	253	}
1da177e4 LT	254
4bf05ece HX	255	iph->protocol = nexthdr[1];
4bf05ece HX	256	pskb_trim(skb, skb->len - alen - padlen - 2);
31a4ab93	257	skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl;
4bf05ece	258
1da177e4 LT	259	return 0;
	260
	261	out:
	262	return -EINVAL;
	263	}
	264
1da177e4 LT	265	static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
	266	{
	267	struct esp_data *esp = x->data;
6b7326c8	268	u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
1da177e4	269
7e49e6de	270	if (x->props.mode == XFRM_MODE_TUNNEL) {
a02a6422	271	mtu = ALIGN(mtu + 2, blksize);
1da177e4 LT	272	} else {
1da177e4 LT	273	/* The worst case. */
d4875b04	274	mtu = ALIGN(mtu + 2, 4) + blksize - 4;
1da177e4 LT	275	}
1da177e4 LT	276	if (esp->conf.padlen)
a02a6422	277	mtu = ALIGN(mtu, esp->conf.padlen);
1da177e4 LT	278
	279	return mtu + x->props.header_len + esp->auth.icv_trunc_len;
	280	}
	281
	282	static void esp4_err(struct sk_buff *skb, u32 info)
	283	{
	284	struct iphdr iph = (struct iphdr)skb->data;
	285	struct ip_esp_hdr esph = (struct ip_esp_hdr)(skb->data+(iph->ihl<<2));
	286	struct xfrm_state *x;
	287
	288	if (skb->h.icmph->type != ICMP_DEST_UNREACH \|\|
	289	skb->h.icmph->code != ICMP_FRAG_NEEDED)
	290	return;
	291
	292	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	293	if (!x)
	294	return;
64ce2073 PM	295	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
64ce2073 PM	296	ntohl(esph->spi), ntohl(iph->daddr));
1da177e4 LT	297	xfrm_state_put(x);
	298	}
	299
	300	static void esp_destroy(struct xfrm_state *x)
	301	{
	302	struct esp_data *esp = x->data;
	303
	304	if (!esp)
	305	return;
	306
6b7326c8	307	crypto_free_blkcipher(esp->conf.tfm);
573dbd95 JJ	308	esp->conf.tfm = NULL;
	309	kfree(esp->conf.ivec);
	310	esp->conf.ivec = NULL;
07d4ee58	311	crypto_free_hash(esp->auth.tfm);
573dbd95 JJ	312	esp->auth.tfm = NULL;
	313	kfree(esp->auth.work_icv);
	314	esp->auth.work_icv = NULL;
1da177e4 LT	315	kfree(esp);
	316	}
	317
72cb6962	318	static int esp_init_state(struct xfrm_state *x)
1da177e4 LT	319	{
1da177e4 LT	320	struct esp_data *esp = NULL;
6b7326c8	321	struct crypto_blkcipher *tfm;
1da177e4 LT	322
	323	/* null auth and encryption can have zero length keys */
	324	if (x->aalg) {
	325	if (x->aalg->alg_key_len > 512)
	326	goto error;
	327	}
	328	if (x->ealg == NULL)
	329	goto error;
	330
0da974f4	331	esp = kzalloc(sizeof(*esp), GFP_KERNEL);
1da177e4 LT	332	if (esp == NULL)
	333	return -ENOMEM;
	334
1da177e4 LT	335	if (x->aalg) {
1da177e4 LT	336	struct xfrm_algo_desc *aalg_desc;
07d4ee58	337	struct crypto_hash *hash;
1da177e4 LT	338
	339	esp->auth.key = x->aalg->alg_key;
	340	esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
07d4ee58 HX	341	hash = crypto_alloc_hash(x->aalg->alg_name, 0,
	342	CRYPTO_ALG_ASYNC);
	343	if (IS_ERR(hash))
	344	goto error;
	345
	346	esp->auth.tfm = hash;
	347	if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
1da177e4	348	goto error;
1da177e4 LT	349
	350	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	351	BUG_ON(!aalg_desc);
	352
	353	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
07d4ee58	354	crypto_hash_digestsize(hash)) {
64ce2073 PM	355	NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
64ce2073 PM	356	x->aalg->alg_name,
07d4ee58	357	crypto_hash_digestsize(hash),
64ce2073	358	aalg_desc->uinfo.auth.icv_fullbits/8);
1da177e4 LT	359	goto error;
	360	}
	361
	362	esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	363	esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	364
	365	esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
	366	if (!esp->auth.work_icv)
	367	goto error;
	368	}
	369	esp->conf.key = x->ealg->alg_key;
	370	esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
6b7326c8 HX	371	tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
6b7326c8 HX	372	if (IS_ERR(tfm))
1da177e4	373	goto error;
6b7326c8 HX	374	esp->conf.tfm = tfm;
6b7326c8 HX	375	esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
1da177e4 LT	376	esp->conf.padlen = 0;
	377	if (esp->conf.ivlen) {
	378	esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
	379	if (unlikely(esp->conf.ivec == NULL))
	380	goto error;
	381	get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	382	}
6b7326c8	383	if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
1da177e4 LT	384	goto error;
1da177e4 LT	385	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
7e49e6de	386	if (x->props.mode == XFRM_MODE_TUNNEL)
1da177e4 LT	387	x->props.header_len += sizeof(struct iphdr);
	388	if (x->encap) {
	389	struct xfrm_encap_tmpl *encap = x->encap;
	390
	391	switch (encap->encap_type) {
	392	default:
	393	goto error;
	394	case UDP_ENCAP_ESPINUDP:
	395	x->props.header_len += sizeof(struct udphdr);
	396	break;
	397	case UDP_ENCAP_ESPINUDP_NON_IKE:
	398	x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
	399	break;
	400	}
	401	}
	402	x->data = esp;
	403	x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
	404	return 0;
	405
	406	error:
	407	x->data = esp;
	408	esp_destroy(x);
	409	x->data = NULL;
	410	return -EINVAL;
	411	}
	412
	413	static struct xfrm_type esp_type =
	414	{
	415	.description = "ESP4",
	416	.owner = THIS_MODULE,
	417	.proto = IPPROTO_ESP,
	418	.init_state = esp_init_state,
	419	.destructor = esp_destroy,
	420	.get_max_size = esp4_get_max_size,
	421	.input = esp_input,
1da177e4 LT	422	.output = esp_output
	423	};
	424
	425	static struct net_protocol esp4_protocol = {
	426	.handler = xfrm4_rcv,
	427	.err_handler = esp4_err,
	428	.no_policy = 1,
	429	};
	430
	431	static int __init esp4_init(void)
	432	{
1da177e4 LT	433	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
	434	printk(KERN_INFO "ip esp init: can't add xfrm type\n");
	435	return -EAGAIN;
	436	}
	437	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
	438	printk(KERN_INFO "ip esp init: can't add protocol\n");
	439	xfrm_unregister_type(&esp_type, AF_INET);
	440	return -EAGAIN;
	441	}
	442	return 0;
	443	}
	444
	445	static void __exit esp4_fini(void)
	446	{
	447	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
	448	printk(KERN_INFO "ip esp close: can't remove protocol\n");
	449	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
	450	printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
	451	}
	452
	453	module_init(esp4_init);
	454	module_exit(esp4_fini);
	455	MODULE_LICENSE("GPL");