[linux.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;
	u8 *tail;
	int blksize;
	int clen;
	int alen;
	int nfrags;

	/* Strip IP+ESP header. */
	__skb_pull(skb, skb_transport_offset(skb));
	/* 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... */
	tail = skb_tail_pointer(trailer);
	do {
		int i;
		for (i=0; i<clen-skb->len - 2; i++)
			tail[i] = i + 1;
	} while (0);
	tail[clen - skb->len - 2] = (clen - skb->len) - 2;
	pskb_put(skb, trailer, clen - skb->len);

	__skb_push(skb, skb->data - skb_network_header(skb));
	top_iph = ip_hdr(skb);
	esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
				     top_iph->ihl * 4);
	top_iph->tot_len = htons(skb->len + alen);
	*(skb_tail_pointer(trailer) - 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;
		__be32 *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 = (__be32 *)(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) {
		if (unlikely(!esp->conf.ivinitted)) {
			get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
			esp->conf.ivinitted = 1;
		}
		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 = ip_hdr(skb);
	ihl = iph->ihl * 4;

	if (x->encap) {
		struct xfrm_encap_tmpl *encap = x->encap;
		struct udphdr *uh = (void *)(skb_network_header(skb) + 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 ||
		    x->props.mode == XFRM_MODE_BEET)
			skb->ip_summed = CHECKSUM_UNNECESSARY;
	}

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

	return 0;

out:
	return -EINVAL;
}

static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
{
	struct esp_data *esp = x->data;
	u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
	u32 align = max_t(u32, blksize, esp->conf.padlen);
	u32 rem;

	mtu -= x->props.header_len + esp->auth.icv_trunc_len;
	rem = mtu & (align - 1);
	mtu &= ~(align - 1);

	switch (x->props.mode) {
	case XFRM_MODE_TUNNEL:
		break;
	default:
	case XFRM_MODE_TRANSPORT:
		/* The worst case */
		mtu -= blksize - 4;
		mtu += min_t(u32, blksize - 4, rem);
		break;
	case XFRM_MODE_BEET:
		/* The worst case. */
		mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
		break;
	}

	return mtu - 2;
}

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 (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
	    icmp_hdr(skb)->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;
	u32 align;

	/* 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;
		esp->conf.ivinitted = 0;
	}
	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);
	else if (x->props.mode == XFRM_MODE_BEET)
		x->props.header_len += IPV4_BEET_PHMAXLEN;
	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;
	align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
	if (esp->conf.padlen)
		align = max_t(u32, align, esp->conf.padlen);
	x->props.trailer_len = align + 1 + esp->auth.icv_trunc_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_mtu	= esp4_get_mtu,
	.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;
1da177e4 LT	23	struct sk_buff *trailer;
27a884dc	24	u8 *tail;
1da177e4 LT	25	int blksize;
	26	int clen;
	27	int alen;
	28	int nfrags;
	29
	30	/* Strip IP+ESP header. */
ea2ae17d	31	__skb_pull(skb, skb_transport_offset(skb));
1da177e4 LT	32	/* Now skb is pure payload to encrypt */
	33
	34	err = -ENOMEM;
	35
	36	/* Round to block size */
	37	clen = skb->len;
	38
	39	esp = x->data;
	40	alen = esp->auth.icv_trunc_len;
	41	tfm = esp->conf.tfm;
6b7326c8 HX	42	desc.tfm = tfm;
	43	desc.flags = 0;
	44	blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
a02a6422	45	clen = ALIGN(clen + 2, blksize);
1da177e4	46	if (esp->conf.padlen)
a02a6422	47	clen = ALIGN(clen, esp->conf.padlen);
1da177e4 LT	48
	49	if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
	50	goto error;
	51
	52	/* Fill padding... */
27a884dc	53	tail = skb_tail_pointer(trailer);
1da177e4 LT	54	do {
	55	int i;
	56	for (i=0; i<clen-skb->len - 2; i++)
27a884dc	57	tail[i] = i + 1;
1da177e4	58	} while (0);
27a884dc	59	tail[clen - skb->len - 2] = (clen - skb->len) - 2;
1da177e4 LT	60	pskb_put(skb, trailer, clen - skb->len);
1da177e4 LT	61
d56f90a7	62	__skb_push(skb, skb->data - skb_network_header(skb));
eddc9ec5	63	top_iph = ip_hdr(skb);
d56f90a7 ACM	64	esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
d56f90a7 ACM	65	top_iph->ihl * 4);
1da177e4	66	top_iph->tot_len = htons(skb->len + alen);
55792258	67	*(skb_tail_pointer(trailer) - 1) = top_iph->protocol;
1da177e4 LT	68
	69	/* this is non-NULL only with UDP Encapsulation */
	70	if (x->encap) {
	71	struct xfrm_encap_tmpl *encap = x->encap;
	72	struct udphdr *uh;
d5a0a1e3	73	__be32 *udpdata32;
1da177e4 LT	74
	75	uh = (struct udphdr *)esph;
	76	uh->source = encap->encap_sport;
	77	uh->dest = encap->encap_dport;
	78	uh->len = htons(skb->len + alen - top_iph->ihl*4);
	79	uh->check = 0;
	80
	81	switch (encap->encap_type) {
	82	default:
	83	case UDP_ENCAP_ESPINUDP:
	84	esph = (struct ip_esp_hdr *)(uh + 1);
	85	break;
	86	case UDP_ENCAP_ESPINUDP_NON_IKE:
d5a0a1e3	87	udpdata32 = (__be32 *)(uh + 1);
1da177e4 LT	88	udpdata32[0] = udpdata32[1] = 0;
	89	esph = (struct ip_esp_hdr *)(udpdata32 + 2);
	90	break;
	91	}
	92
	93	top_iph->protocol = IPPROTO_UDP;
	94	} else
	95	top_iph->protocol = IPPROTO_ESP;
	96
	97	esph->spi = x->id.spi;
	98	esph->seq_no = htonl(++x->replay.oseq);
9500e8a8	99	xfrm_aevent_doreplay(x);
1da177e4	100
e4bec827 DM	101	if (esp->conf.ivlen) {
	102	if (unlikely(!esp->conf.ivinitted)) {
	103	get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	104	esp->conf.ivinitted = 1;
	105	}
6b7326c8	106	crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
e4bec827	107	}
1da177e4 LT	108
	109	do {
	110	struct scatterlist *sg = &esp->sgbuf[0];
	111
	112	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	113	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	114	if (!sg)
	115	goto error;
	116	}
	117	skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
6b7326c8	118	err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
1da177e4 LT	119	if (unlikely(sg != &esp->sgbuf[0]))
	120	kfree(sg);
	121	} while (0);
	122
6b7326c8 HX	123	if (unlikely(err))
	124	goto error;
	125
1da177e4	126	if (esp->conf.ivlen) {
6b7326c8 HX	127	memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
6b7326c8 HX	128	crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
1da177e4 LT	129	}
	130
	131	if (esp->auth.icv_full_len) {
07d4ee58 HX	132	err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
	133	sizeof(*esph) + esp->conf.ivlen + clen);
	134	memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
1da177e4 LT	135	}
	136
	137	ip_send_check(top_iph);
	138
1da177e4 LT	139	error:
	140	return err;
	141	}
	142
	143	/*
	144	* Note: detecting truncated vs. non-truncated authentication data is very
	145	* expensive, so we only support truncated data, which is the recommended
	146	* and common case.
	147	*/
e695633e	148	static int esp_input(struct xfrm_state x, struct sk_buff skb)
1da177e4 LT	149	{
	150	struct iphdr *iph;
	151	struct ip_esp_hdr *esph;
	152	struct esp_data *esp = x->data;
6b7326c8 HX	153	struct crypto_blkcipher *tfm = esp->conf.tfm;
6b7326c8 HX	154	struct blkcipher_desc desc = { .tfm = tfm };
1da177e4	155	struct sk_buff *trailer;
6b7326c8	156	int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
1da177e4 LT	157	int alen = esp->auth.icv_trunc_len;
	158	int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
	159	int nfrags;
31a4ab93	160	int ihl;
4bf05ece HX	161	u8 nexthdr[2];
4bf05ece HX	162	struct scatterlist *sg;
4bf05ece	163	int padlen;
6b7326c8	164	int err;
1da177e4 LT	165
	166	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
	167	goto out;
	168
	169	if (elen <= 0 \|\| (elen & (blksize-1)))
	170	goto out;
	171
	172	/* If integrity check is required, do this. */
	173	if (esp->auth.icv_full_len) {
07d4ee58	174	u8 sum[alen];
1da177e4	175
07d4ee58 HX	176	err = esp_mac_digest(esp, skb, 0, skb->len - alen);
	177	if (err)
	178	goto out;
	179
	180	if (skb_copy_bits(skb, skb->len - alen, sum, alen))
1da177e4 LT	181	BUG();
1da177e4 LT	182
07d4ee58	183	if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
1da177e4 LT	184	x->stats.integrity_failed++;
	185	goto out;
	186	}
	187	}
	188
	189	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
	190	goto out;
	191
	192	skb->ip_summed = CHECKSUM_NONE;
	193
	194	esph = (struct ip_esp_hdr*)skb->data;
1da177e4 LT	195
	196	/* Get ivec. This can be wrong, check against another impls. */
	197	if (esp->conf.ivlen)
6b7326c8	198	crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
1da177e4	199
4bf05ece	200	sg = &esp->sgbuf[0];
1da177e4	201
4bf05ece HX	202	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	203	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	204	if (!sg)
	205	goto out;
	206	}
	207	skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
6b7326c8	208	err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
4bf05ece HX	209	if (unlikely(sg != &esp->sgbuf[0]))
4bf05ece HX	210	kfree(sg);
6b7326c8 HX	211	if (unlikely(err))
6b7326c8 HX	212	return err;
1da177e4	213
4bf05ece HX	214	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
4bf05ece HX	215	BUG();
1da177e4	216
4bf05ece HX	217	padlen = nexthdr[0];
	218	if (padlen+2 >= elen)
	219	goto out;
1da177e4	220
e905a9ed	221	/* ... check padding bits here. Silly. :-) */
1da177e4	222
eddc9ec5	223	iph = ip_hdr(skb);
31a4ab93 HX	224	ihl = iph->ihl * 4;
31a4ab93 HX	225
752c1f4c HX	226	if (x->encap) {
752c1f4c HX	227	struct xfrm_encap_tmpl *encap = x->encap;
d56f90a7	228	struct udphdr uh = (void )(skb_network_header(skb) + ihl);
752c1f4c HX	229
	230	/*
	231	* 1) if the NAT-T peer's IP or port changed then
	232	* advertize the change to the keying daemon.
	233	* This is an inbound SA, so just compare
	234	* SRC ports.
	235	*/
	236	if (iph->saddr != x->props.saddr.a4 \|\|
	237	uh->source != encap->encap_sport) {
	238	xfrm_address_t ipaddr;
	239
	240	ipaddr.a4 = iph->saddr;
	241	km_new_mapping(x, &ipaddr, uh->source);
e905a9ed	242
752c1f4c HX	243	/* XXX: perhaps add an extra
	244	* policy check here, to see
	245	* if we should allow or
	246	* reject a packet from a
	247	* different source
	248	* address/port.
	249	*/
1da177e4	250	}
e905a9ed	251
752c1f4c HX	252	/*
	253	* 2) ignore UDP/TCP checksums in case
	254	* of NAT-T in Transport Mode, or
	255	* perform other post-processing fixes
	256	* as per draft-ietf-ipsec-udp-encaps-06,
	257	* section 3.1.2
	258	*/
0a69452c DB	259	if (x->props.mode == XFRM_MODE_TRANSPORT \|\|
0a69452c DB	260	x->props.mode == XFRM_MODE_BEET)
752c1f4c	261	skb->ip_summed = CHECKSUM_UNNECESSARY;
1da177e4 LT	262	}
1da177e4 LT	263
4bf05ece HX	264	iph->protocol = nexthdr[1];
4bf05ece HX	265	pskb_trim(skb, skb->len - alen - padlen - 2);
967b05f6 ACM	266	__skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
967b05f6 ACM	267	skb_set_transport_header(skb, -ihl);
4bf05ece	268
1da177e4 LT	269	return 0;
	270
	271	out:
	272	return -EINVAL;
	273	}
	274
c5c25238	275	static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
1da177e4 LT	276	{
1da177e4 LT	277	struct esp_data *esp = x->data;
6b7326c8	278	u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
c5c25238 PM	279	u32 align = max_t(u32, blksize, esp->conf.padlen);
	280	u32 rem;
	281
	282	mtu -= x->props.header_len + esp->auth.icv_trunc_len;
	283	rem = mtu & (align - 1);
	284	mtu &= ~(align - 1);
0a69452c DB	285
	286	switch (x->props.mode) {
	287	case XFRM_MODE_TUNNEL:
0a69452c DB	288	break;
	289	default:
	290	case XFRM_MODE_TRANSPORT:
	291	/* The worst case */
c5c25238 PM	292	mtu -= blksize - 4;
c5c25238 PM	293	mtu += min_t(u32, blksize - 4, rem);
0a69452c DB	294	break;
0a69452c DB	295	case XFRM_MODE_BEET:
e905a9ed	296	/* The worst case. */
c5c25238	297	mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
0a69452c	298	break;
1da177e4	299	}
0a69452c	300
c5c25238	301	return mtu - 2;
1da177e4 LT	302	}
	303
	304	static void esp4_err(struct sk_buff *skb, u32 info)
	305	{
	306	struct iphdr iph = (struct iphdr)skb->data;
	307	struct ip_esp_hdr esph = (struct ip_esp_hdr)(skb->data+(iph->ihl<<2));
	308	struct xfrm_state *x;
	309
88c7664f ACM	310	if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH \|\|
88c7664f ACM	311	icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
1da177e4 LT	312	return;
	313
	314	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	315	if (!x)
	316	return;
64ce2073 PM	317	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
64ce2073 PM	318	ntohl(esph->spi), ntohl(iph->daddr));
1da177e4 LT	319	xfrm_state_put(x);
	320	}
	321
	322	static void esp_destroy(struct xfrm_state *x)
	323	{
	324	struct esp_data *esp = x->data;
	325
	326	if (!esp)
	327	return;
	328
6b7326c8	329	crypto_free_blkcipher(esp->conf.tfm);
573dbd95 JJ	330	esp->conf.tfm = NULL;
	331	kfree(esp->conf.ivec);
	332	esp->conf.ivec = NULL;
07d4ee58	333	crypto_free_hash(esp->auth.tfm);
573dbd95 JJ	334	esp->auth.tfm = NULL;
	335	kfree(esp->auth.work_icv);
	336	esp->auth.work_icv = NULL;
1da177e4 LT	337	kfree(esp);
	338	}
	339
72cb6962	340	static int esp_init_state(struct xfrm_state *x)
1da177e4 LT	341	{
1da177e4 LT	342	struct esp_data *esp = NULL;
6b7326c8	343	struct crypto_blkcipher *tfm;
c5c25238	344	u32 align;
1da177e4 LT	345
	346	/* null auth and encryption can have zero length keys */
	347	if (x->aalg) {
	348	if (x->aalg->alg_key_len > 512)
	349	goto error;
	350	}
	351	if (x->ealg == NULL)
	352	goto error;
	353
0da974f4	354	esp = kzalloc(sizeof(*esp), GFP_KERNEL);
1da177e4 LT	355	if (esp == NULL)
	356	return -ENOMEM;
	357
1da177e4 LT	358	if (x->aalg) {
1da177e4 LT	359	struct xfrm_algo_desc *aalg_desc;
07d4ee58	360	struct crypto_hash *hash;
1da177e4 LT	361
	362	esp->auth.key = x->aalg->alg_key;
	363	esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
07d4ee58 HX	364	hash = crypto_alloc_hash(x->aalg->alg_name, 0,
	365	CRYPTO_ALG_ASYNC);
	366	if (IS_ERR(hash))
	367	goto error;
	368
	369	esp->auth.tfm = hash;
	370	if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
1da177e4	371	goto error;
1da177e4 LT	372
	373	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	374	BUG_ON(!aalg_desc);
	375
	376	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
07d4ee58	377	crypto_hash_digestsize(hash)) {
64ce2073 PM	378	NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
64ce2073 PM	379	x->aalg->alg_name,
07d4ee58	380	crypto_hash_digestsize(hash),
64ce2073	381	aalg_desc->uinfo.auth.icv_fullbits/8);
1da177e4 LT	382	goto error;
	383	}
	384
	385	esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	386	esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	387
	388	esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
	389	if (!esp->auth.work_icv)
	390	goto error;
	391	}
	392	esp->conf.key = x->ealg->alg_key;
	393	esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
6b7326c8 HX	394	tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
6b7326c8 HX	395	if (IS_ERR(tfm))
1da177e4	396	goto error;
6b7326c8 HX	397	esp->conf.tfm = tfm;
6b7326c8 HX	398	esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
1da177e4 LT	399	esp->conf.padlen = 0;
	400	if (esp->conf.ivlen) {
	401	esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
	402	if (unlikely(esp->conf.ivec == NULL))
	403	goto error;
e4bec827	404	esp->conf.ivinitted = 0;
1da177e4	405	}
6b7326c8	406	if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
1da177e4 LT	407	goto error;
1da177e4 LT	408	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
7e49e6de	409	if (x->props.mode == XFRM_MODE_TUNNEL)
1da177e4	410	x->props.header_len += sizeof(struct iphdr);
ac758e3c PM	411	else if (x->props.mode == XFRM_MODE_BEET)
ac758e3c PM	412	x->props.header_len += IPV4_BEET_PHMAXLEN;
1da177e4 LT	413	if (x->encap) {
	414	struct xfrm_encap_tmpl *encap = x->encap;
	415
	416	switch (encap->encap_type) {
	417	default:
	418	goto error;
	419	case UDP_ENCAP_ESPINUDP:
	420	x->props.header_len += sizeof(struct udphdr);
	421	break;
	422	case UDP_ENCAP_ESPINUDP_NON_IKE:
	423	x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
	424	break;
	425	}
	426	}
	427	x->data = esp;
c5c25238 PM	428	align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
	429	if (esp->conf.padlen)
	430	align = max_t(u32, align, esp->conf.padlen);
	431	x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len;
1da177e4 LT	432	return 0;
	433
	434	error:
	435	x->data = esp;
	436	esp_destroy(x);
	437	x->data = NULL;
	438	return -EINVAL;
	439	}
	440
	441	static struct xfrm_type esp_type =
	442	{
	443	.description = "ESP4",
	444	.owner = THIS_MODULE,
	445	.proto = IPPROTO_ESP,
	446	.init_state = esp_init_state,
	447	.destructor = esp_destroy,
c5c25238	448	.get_mtu = esp4_get_mtu,
1da177e4	449	.input = esp_input,
1da177e4 LT	450	.output = esp_output
	451	};
	452
	453	static struct net_protocol esp4_protocol = {
	454	.handler = xfrm4_rcv,
	455	.err_handler = esp4_err,
	456	.no_policy = 1,
	457	};
	458
	459	static int __init esp4_init(void)
	460	{
1da177e4 LT	461	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
	462	printk(KERN_INFO "ip esp init: can't add xfrm type\n");
	463	return -EAGAIN;
	464	}
	465	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
	466	printk(KERN_INFO "ip esp init: can't add protocol\n");
	467	xfrm_unregister_type(&esp_type, AF_INET);
	468	return -EAGAIN;
	469	}
	470	return 0;
	471	}
	472
	473	static void __exit esp4_fini(void)
	474	{
	475	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
	476	printk(KERN_INFO "ip esp close: can't remove protocol\n");
	477	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
	478	printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
	479	}
	480
	481	module_init(esp4_init);
	482	module_exit(esp4_fini);
	483	MODULE_LICENSE("GPL");