[mirror_ubuntu-bionic-kernel.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 <linux/spinlock.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;

	/* 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_network_offset(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;

	spin_lock_bh(&x->lock);

	/* 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(XFRM_SKB_CB(skb)->seq);

	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 unlock;
		}
		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 unlock;

	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);
	}

unlock:
	spin_unlock_bh(&x->lock);

	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)
			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;

	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;

		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, x->aalg->alg_key,
				       (x->aalg->alg_key_len + 7) / 8))
			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;
	}

	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, x->ealg->alg_key,
				    (x->ealg->alg_key_len + 7) / 8))
		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,
	.flags		= XFRM_TYPE_REPLAY_PROT,
	.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");
MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);
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>
1da177e4 LT	10	#include <linux/random.h>
b7c6538c	11	#include <linux/spinlock.h>
1da177e4	12	#include <net/icmp.h>
14c85021	13	#include <net/protocol.h>
1da177e4 LT	14	#include <net/udp.h>
1da177e4 LT	15
1da177e4 LT	16	static int esp_output(struct xfrm_state x, struct sk_buff skb)
	17	{
	18	int err;
	19	struct iphdr *top_iph;
	20	struct ip_esp_hdr *esph;
6b7326c8 HX	21	struct crypto_blkcipher *tfm;
6b7326c8 HX	22	struct blkcipher_desc desc;
1da177e4 LT	23	struct esp_data *esp;
1da177e4 LT	24	struct sk_buff *trailer;
27a884dc	25	u8 *tail;
1da177e4 LT	26	int blksize;
	27	int clen;
	28	int alen;
	29	int nfrags;
	30
7b277b1a	31	/* skb is pure payload to encrypt */
1da177e4 LT	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... */
27a884dc	52	tail = skb_tail_pointer(trailer);
1da177e4 LT	53	do {
	54	int i;
	55	for (i=0; i<clen-skb->len - 2; i++)
27a884dc	56	tail[i] = i + 1;
1da177e4	57	} while (0);
27a884dc	58	tail[clen - skb->len - 2] = (clen - skb->len) - 2;
1da177e4 LT	59	pskb_put(skb, trailer, clen - skb->len);
1da177e4 LT	60
7b277b1a	61	skb_push(skb, -skb_network_offset(skb));
eddc9ec5	62	top_iph = ip_hdr(skb);
d56f90a7 ACM	63	esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
d56f90a7 ACM	64	top_iph->ihl * 4);
1da177e4	65	top_iph->tot_len = htons(skb->len + alen);
55792258	66	*(skb_tail_pointer(trailer) - 1) = top_iph->protocol;
1da177e4	67
b7c6538c HX	68	spin_lock_bh(&x->lock);
b7c6538c HX	69
1da177e4 LT	70	/* this is non-NULL only with UDP Encapsulation */
	71	if (x->encap) {
	72	struct xfrm_encap_tmpl *encap = x->encap;
	73	struct udphdr *uh;
d5a0a1e3	74	__be32 *udpdata32;
1da177e4 LT	75
	76	uh = (struct udphdr *)esph;
	77	uh->source = encap->encap_sport;
	78	uh->dest = encap->encap_dport;
	79	uh->len = htons(skb->len + alen - top_iph->ihl*4);
	80	uh->check = 0;
	81
	82	switch (encap->encap_type) {
	83	default:
	84	case UDP_ENCAP_ESPINUDP:
	85	esph = (struct ip_esp_hdr *)(uh + 1);
	86	break;
	87	case UDP_ENCAP_ESPINUDP_NON_IKE:
d5a0a1e3	88	udpdata32 = (__be32 *)(uh + 1);
1da177e4 LT	89	udpdata32[0] = udpdata32[1] = 0;
	90	esph = (struct ip_esp_hdr *)(udpdata32 + 2);
	91	break;
	92	}
	93
	94	top_iph->protocol = IPPROTO_UDP;
	95	} else
	96	top_iph->protocol = IPPROTO_ESP;
	97
	98	esph->spi = x->id.spi;
436a0a40	99	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
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)
b7c6538c	115	goto unlock;
1da177e4 LT	116	}
1da177e4 LT	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	123	if (unlikely(err))
b7c6538c	124	goto unlock;
6b7326c8	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	}
1da177e4 LT	136
b7c6538c HX	137	unlock:
	138	spin_unlock_bh(&x->lock);
	139
1da177e4 LT	140	ip_send_check(top_iph);
1da177e4 LT	141
1da177e4 LT	142	error:
	143	return err;
	144	}
	145
	146	/*
	147	* Note: detecting truncated vs. non-truncated authentication data is very
	148	* expensive, so we only support truncated data, which is the recommended
	149	* and common case.
	150	*/
e695633e	151	static int esp_input(struct xfrm_state x, struct sk_buff skb)
1da177e4 LT	152	{
	153	struct iphdr *iph;
	154	struct ip_esp_hdr *esph;
	155	struct esp_data *esp = x->data;
6b7326c8 HX	156	struct crypto_blkcipher *tfm = esp->conf.tfm;
6b7326c8 HX	157	struct blkcipher_desc desc = { .tfm = tfm };
1da177e4	158	struct sk_buff *trailer;
6b7326c8	159	int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
1da177e4 LT	160	int alen = esp->auth.icv_trunc_len;
	161	int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
	162	int nfrags;
31a4ab93	163	int ihl;
4bf05ece HX	164	u8 nexthdr[2];
4bf05ece HX	165	struct scatterlist *sg;
4bf05ece	166	int padlen;
6b7326c8	167	int err;
1da177e4 LT	168
	169	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
	170	goto out;
	171
	172	if (elen <= 0 \|\| (elen & (blksize-1)))
	173	goto out;
	174
	175	/* If integrity check is required, do this. */
	176	if (esp->auth.icv_full_len) {
07d4ee58	177	u8 sum[alen];
1da177e4	178
07d4ee58 HX	179	err = esp_mac_digest(esp, skb, 0, skb->len - alen);
	180	if (err)
	181	goto out;
	182
	183	if (skb_copy_bits(skb, skb->len - alen, sum, alen))
1da177e4 LT	184	BUG();
1da177e4 LT	185
07d4ee58	186	if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
1da177e4 LT	187	x->stats.integrity_failed++;
	188	goto out;
	189	}
	190	}
	191
	192	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
	193	goto out;
	194
	195	skb->ip_summed = CHECKSUM_NONE;
	196
	197	esph = (struct ip_esp_hdr*)skb->data;
1da177e4 LT	198
	199	/* Get ivec. This can be wrong, check against another impls. */
	200	if (esp->conf.ivlen)
6b7326c8	201	crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
1da177e4	202
4bf05ece	203	sg = &esp->sgbuf[0];
1da177e4	204
4bf05ece HX	205	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	206	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	207	if (!sg)
	208	goto out;
	209	}
	210	skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
6b7326c8	211	err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
4bf05ece HX	212	if (unlikely(sg != &esp->sgbuf[0]))
4bf05ece HX	213	kfree(sg);
6b7326c8 HX	214	if (unlikely(err))
6b7326c8 HX	215	return err;
1da177e4	216
4bf05ece HX	217	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
4bf05ece HX	218	BUG();
1da177e4	219
4bf05ece HX	220	padlen = nexthdr[0];
	221	if (padlen+2 >= elen)
	222	goto out;
1da177e4	223
e905a9ed	224	/* ... check padding bits here. Silly. :-) */
1da177e4	225
eddc9ec5	226	iph = ip_hdr(skb);
31a4ab93 HX	227	ihl = iph->ihl * 4;
31a4ab93 HX	228
752c1f4c HX	229	if (x->encap) {
752c1f4c HX	230	struct xfrm_encap_tmpl *encap = x->encap;
d56f90a7	231	struct udphdr uh = (void )(skb_network_header(skb) + ihl);
752c1f4c HX	232
	233	/*
	234	* 1) if the NAT-T peer's IP or port changed then
	235	* advertize the change to the keying daemon.
	236	* This is an inbound SA, so just compare
	237	* SRC ports.
	238	*/
	239	if (iph->saddr != x->props.saddr.a4 \|\|
	240	uh->source != encap->encap_sport) {
	241	xfrm_address_t ipaddr;
	242
	243	ipaddr.a4 = iph->saddr;
	244	km_new_mapping(x, &ipaddr, uh->source);
e905a9ed	245
752c1f4c HX	246	/* XXX: perhaps add an extra
	247	* policy check here, to see
	248	* if we should allow or
	249	* reject a packet from a
	250	* different source
	251	* address/port.
	252	*/
1da177e4	253	}
e905a9ed	254
752c1f4c HX	255	/*
	256	* 2) ignore UDP/TCP checksums in case
	257	* of NAT-T in Transport Mode, or
	258	* perform other post-processing fixes
	259	* as per draft-ietf-ipsec-udp-encaps-06,
	260	* section 3.1.2
	261	*/
8bd17075	262	if (x->props.mode == XFRM_MODE_TRANSPORT)
752c1f4c	263	skb->ip_summed = CHECKSUM_UNNECESSARY;
1da177e4 LT	264	}
1da177e4 LT	265
4bf05ece HX	266	iph->protocol = nexthdr[1];
4bf05ece HX	267	pskb_trim(skb, skb->len - alen - padlen - 2);
967b05f6 ACM	268	__skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
967b05f6 ACM	269	skb_set_transport_header(skb, -ihl);
4bf05ece	270
1da177e4 LT	271	return 0;
	272
	273	out:
	274	return -EINVAL;
	275	}
	276
c5c25238	277	static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
1da177e4 LT	278	{
1da177e4 LT	279	struct esp_data *esp = x->data;
6b7326c8	280	u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
c5c25238 PM	281	u32 align = max_t(u32, blksize, esp->conf.padlen);
	282	u32 rem;
	283
	284	mtu -= x->props.header_len + esp->auth.icv_trunc_len;
	285	rem = mtu & (align - 1);
	286	mtu &= ~(align - 1);
0a69452c DB	287
	288	switch (x->props.mode) {
	289	case XFRM_MODE_TUNNEL:
0a69452c DB	290	break;
	291	default:
	292	case XFRM_MODE_TRANSPORT:
	293	/* The worst case */
c5c25238 PM	294	mtu -= blksize - 4;
c5c25238 PM	295	mtu += min_t(u32, blksize - 4, rem);
0a69452c DB	296	break;
0a69452c DB	297	case XFRM_MODE_BEET:
e905a9ed	298	/* The worst case. */
c5c25238	299	mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
0a69452c	300	break;
1da177e4	301	}
0a69452c	302
c5c25238	303	return mtu - 2;
1da177e4 LT	304	}
	305
	306	static void esp4_err(struct sk_buff *skb, u32 info)
	307	{
	308	struct iphdr iph = (struct iphdr)skb->data;
	309	struct ip_esp_hdr esph = (struct ip_esp_hdr)(skb->data+(iph->ihl<<2));
	310	struct xfrm_state *x;
	311
88c7664f ACM	312	if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH \|\|
88c7664f ACM	313	icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
1da177e4 LT	314	return;
	315
	316	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	317	if (!x)
	318	return;
64ce2073 PM	319	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
64ce2073 PM	320	ntohl(esph->spi), ntohl(iph->daddr));
1da177e4 LT	321	xfrm_state_put(x);
	322	}
	323
	324	static void esp_destroy(struct xfrm_state *x)
	325	{
	326	struct esp_data *esp = x->data;
	327
	328	if (!esp)
	329	return;
	330
6b7326c8	331	crypto_free_blkcipher(esp->conf.tfm);
573dbd95 JJ	332	esp->conf.tfm = NULL;
	333	kfree(esp->conf.ivec);
	334	esp->conf.ivec = NULL;
07d4ee58	335	crypto_free_hash(esp->auth.tfm);
573dbd95 JJ	336	esp->auth.tfm = NULL;
	337	kfree(esp->auth.work_icv);
	338	esp->auth.work_icv = NULL;
1da177e4 LT	339	kfree(esp);
	340	}
	341
72cb6962	342	static int esp_init_state(struct xfrm_state *x)
1da177e4 LT	343	{
1da177e4 LT	344	struct esp_data *esp = NULL;
6b7326c8	345	struct crypto_blkcipher *tfm;
c5c25238	346	u32 align;
1da177e4	347
1da177e4 LT	348	if (x->ealg == NULL)
	349	goto error;
	350
0da974f4	351	esp = kzalloc(sizeof(*esp), GFP_KERNEL);
1da177e4 LT	352	if (esp == NULL)
	353	return -ENOMEM;
	354
1da177e4 LT	355	if (x->aalg) {
1da177e4 LT	356	struct xfrm_algo_desc *aalg_desc;
07d4ee58	357	struct crypto_hash *hash;
1da177e4	358
07d4ee58 HX	359	hash = crypto_alloc_hash(x->aalg->alg_name, 0,
	360	CRYPTO_ALG_ASYNC);
	361	if (IS_ERR(hash))
	362	goto error;
	363
	364	esp->auth.tfm = hash;
4b7137ff HX	365	if (crypto_hash_setkey(hash, x->aalg->alg_key,
4b7137ff HX	366	(x->aalg->alg_key_len + 7) / 8))
1da177e4	367	goto error;
1da177e4 LT	368
	369	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	370	BUG_ON(!aalg_desc);
	371
	372	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
07d4ee58	373	crypto_hash_digestsize(hash)) {
64ce2073 PM	374	NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
64ce2073 PM	375	x->aalg->alg_name,
07d4ee58	376	crypto_hash_digestsize(hash),
64ce2073	377	aalg_desc->uinfo.auth.icv_fullbits/8);
1da177e4 LT	378	goto error;
	379	}
	380
	381	esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	382	esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	383
	384	esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
	385	if (!esp->auth.work_icv)
	386	goto error;
	387	}
4b7137ff	388
6b7326c8 HX	389	tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
6b7326c8 HX	390	if (IS_ERR(tfm))
1da177e4	391	goto error;
6b7326c8 HX	392	esp->conf.tfm = tfm;
6b7326c8 HX	393	esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
1da177e4 LT	394	esp->conf.padlen = 0;
	395	if (esp->conf.ivlen) {
	396	esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
	397	if (unlikely(esp->conf.ivec == NULL))
	398	goto error;
e4bec827	399	esp->conf.ivinitted = 0;
1da177e4	400	}
4b7137ff HX	401	if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
4b7137ff HX	402	(x->ealg->alg_key_len + 7) / 8))
1da177e4 LT	403	goto error;
1da177e4 LT	404	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
7e49e6de	405	if (x->props.mode == XFRM_MODE_TUNNEL)
1da177e4	406	x->props.header_len += sizeof(struct iphdr);
ac758e3c PM	407	else if (x->props.mode == XFRM_MODE_BEET)
ac758e3c PM	408	x->props.header_len += IPV4_BEET_PHMAXLEN;
1da177e4 LT	409	if (x->encap) {
	410	struct xfrm_encap_tmpl *encap = x->encap;
	411
	412	switch (encap->encap_type) {
	413	default:
	414	goto error;
	415	case UDP_ENCAP_ESPINUDP:
	416	x->props.header_len += sizeof(struct udphdr);
	417	break;
	418	case UDP_ENCAP_ESPINUDP_NON_IKE:
	419	x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
	420	break;
	421	}
	422	}
	423	x->data = esp;
c5c25238 PM	424	align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
	425	if (esp->conf.padlen)
	426	align = max_t(u32, align, esp->conf.padlen);
	427	x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len;
1da177e4 LT	428	return 0;
	429
	430	error:
	431	x->data = esp;
	432	esp_destroy(x);
	433	x->data = NULL;
	434	return -EINVAL;
	435	}
	436
	437	static struct xfrm_type esp_type =
	438	{
	439	.description = "ESP4",
	440	.owner = THIS_MODULE,
	441	.proto = IPPROTO_ESP,
436a0a40	442	.flags = XFRM_TYPE_REPLAY_PROT,
1da177e4 LT	443	.init_state = esp_init_state,
1da177e4 LT	444	.destructor = esp_destroy,
c5c25238	445	.get_mtu = esp4_get_mtu,
1da177e4	446	.input = esp_input,
1da177e4 LT	447	.output = esp_output
	448	};
	449
	450	static struct net_protocol esp4_protocol = {
	451	.handler = xfrm4_rcv,
	452	.err_handler = esp4_err,
	453	.no_policy = 1,
	454	};
	455
	456	static int __init esp4_init(void)
	457	{
1da177e4 LT	458	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
	459	printk(KERN_INFO "ip esp init: can't add xfrm type\n");
	460	return -EAGAIN;
	461	}
	462	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
	463	printk(KERN_INFO "ip esp init: can't add protocol\n");
	464	xfrm_unregister_type(&esp_type, AF_INET);
	465	return -EAGAIN;
	466	}
	467	return 0;
	468	}
	469
	470	static void __exit esp4_fini(void)
	471	{
	472	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
	473	printk(KERN_INFO "ip esp close: can't remove protocol\n");
	474	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
	475	printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
	476	}
	477
	478	module_init(esp4_init);
	479	module_exit(esp4_fini);
	480	MODULE_LICENSE("GPL");
d3d6dd3a	481	MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);