[mirror_ubuntu-hirsute-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 <linux/scatterlist.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/pfkeyv2.h>
#include <linux/random.h>
#include <linux/spinlock.h>
#include <linux/in6.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 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));
	esph = ip_esp_hdr(skb);
	*(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb);
	*skb_mac_header(skb) = IPPROTO_ESP;

	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 - skb_transport_offset(skb));
		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;
		}

		*skb_mac_header(skb) = IPPROTO_UDP;
	}

	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;
		}
		sg_init_table(sg, nfrags);
		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);

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(*esph) - esp->conf.ivlen - alen;
	int nfrags;
	int ihl;
	u8 nexthdr[2];
	struct scatterlist *sg;
	int padlen;
	int err = -EINVAL;

	if (!pskb_may_pull(skb, sizeof(*esph)))
		goto out;

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

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

	skb->ip_summed = CHECKSUM_NONE;

	spin_lock(&x->lock);

	/* 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 unlock;

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

		if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
			err = -EBADMSG;
			goto unlock;
		}
	}

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

unlock:
	spin_unlock(&x->lock);

	if (unlikely(err))
		goto out;

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

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

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

	/* RFC4303: Drop dummy packets without any error */
	if (nexthdr[1] == IPPROTO_NONE)
		goto out;

	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;
	}

	pskb_trim(skb, skb->len - alen - padlen - 2);
	__skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
	skb_set_transport_header(skb, -ihl);

	return nexthdr[1];

out:
	return err;
}

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>
72998d8c	6	#include <linux/scatterlist.h>
1da177e4	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>
2017a72c	12	#include <linux/in6.h>
1da177e4	13	#include <net/icmp.h>
14c85021	14	#include <net/protocol.h>
1da177e4 LT	15	#include <net/udp.h>
1da177e4 LT	16
1da177e4 LT	17	static int esp_output(struct xfrm_state x, struct sk_buff skb)
	18	{
	19	int err;
1da177e4	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));
87bdc48d	62	esph = ip_esp_hdr(skb);
37fedd3a HX	63	(skb_tail_pointer(trailer) - 1) = skb_mac_header(skb);
37fedd3a HX	64	*skb_mac_header(skb) = IPPROTO_ESP;
1da177e4	65
b7c6538c HX	66	spin_lock_bh(&x->lock);
b7c6538c HX	67
1da177e4 LT	68	/* this is non-NULL only with UDP Encapsulation */
	69	if (x->encap) {
	70	struct xfrm_encap_tmpl *encap = x->encap;
	71	struct udphdr *uh;
d5a0a1e3	72	__be32 *udpdata32;
1da177e4 LT	73
	74	uh = (struct udphdr *)esph;
	75	uh->source = encap->encap_sport;
	76	uh->dest = encap->encap_dport;
ceb1eec8	77	uh->len = htons(skb->len + alen - skb_transport_offset(skb));
1da177e4 LT	78	uh->check = 0;
	79
	80	switch (encap->encap_type) {
	81	default:
	82	case UDP_ENCAP_ESPINUDP:
	83	esph = (struct ip_esp_hdr *)(uh + 1);
	84	break;
	85	case UDP_ENCAP_ESPINUDP_NON_IKE:
d5a0a1e3	86	udpdata32 = (__be32 *)(uh + 1);
1da177e4 LT	87	udpdata32[0] = udpdata32[1] = 0;
	88	esph = (struct ip_esp_hdr *)(udpdata32 + 2);
	89	break;
	90	}
	91
37fedd3a HX	92	*skb_mac_header(skb) = IPPROTO_UDP;
37fedd3a HX	93	}
1da177e4 LT	94
1da177e4 LT	95	esph->spi = x->id.spi;
436a0a40	96	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
1da177e4	97
e4bec827 DM	98	if (esp->conf.ivlen) {
	99	if (unlikely(!esp->conf.ivinitted)) {
	100	get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	101	esp->conf.ivinitted = 1;
	102	}
6b7326c8	103	crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
e4bec827	104	}
1da177e4 LT	105
	106	do {
	107	struct scatterlist *sg = &esp->sgbuf[0];
	108
	109	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	110	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	111	if (!sg)
b7c6538c	112	goto unlock;
1da177e4	113	}
ed0e7e0c	114	sg_init_table(sg, nfrags);
51c739d1 DM	115	skb_to_sgvec(skb, sg,
	116	esph->enc_data +
	117	esp->conf.ivlen -
	118	skb->data, clen);
6b7326c8	119	err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
1da177e4 LT	120	if (unlikely(sg != &esp->sgbuf[0]))
	121	kfree(sg);
	122	} while (0);
	123
6b7326c8	124	if (unlikely(err))
b7c6538c	125	goto unlock;
6b7326c8	126
1da177e4	127	if (esp->conf.ivlen) {
6b7326c8 HX	128	memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
6b7326c8 HX	129	crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
1da177e4 LT	130	}
	131
	132	if (esp->auth.icv_full_len) {
07d4ee58 HX	133	err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
	134	sizeof(*esph) + esp->conf.ivlen + clen);
	135	memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
1da177e4 LT	136	}
1da177e4 LT	137
b7c6538c HX	138	unlock:
	139	spin_unlock_bh(&x->lock);
	140
1da177e4 LT	141	error:
	142	return err;
	143	}
	144
	145	/*
	146	* Note: detecting truncated vs. non-truncated authentication data is very
	147	* expensive, so we only support truncated data, which is the recommended
	148	* and common case.
	149	*/
e695633e	150	static int esp_input(struct xfrm_state x, struct sk_buff skb)
1da177e4 LT	151	{
	152	struct iphdr *iph;
	153	struct ip_esp_hdr *esph;
	154	struct esp_data *esp = x->data;
6b7326c8 HX	155	struct crypto_blkcipher *tfm = esp->conf.tfm;
6b7326c8 HX	156	struct blkcipher_desc desc = { .tfm = tfm };
1da177e4	157	struct sk_buff *trailer;
6b7326c8	158	int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
1da177e4	159	int alen = esp->auth.icv_trunc_len;
87bdc48d	160	int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen;
1da177e4	161	int nfrags;
31a4ab93	162	int ihl;
4bf05ece HX	163	u8 nexthdr[2];
4bf05ece HX	164	struct scatterlist *sg;
4bf05ece	165	int padlen;
668dc8af	166	int err = -EINVAL;
1da177e4	167
87bdc48d	168	if (!pskb_may_pull(skb, sizeof(*esph)))
1da177e4 LT	169	goto out;
	170
	171	if (elen <= 0 \|\| (elen & (blksize-1)))
	172	goto out;
	173
0ebea8ef HX	174	if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
	175	goto out;
	176	nfrags = err;
	177
	178	skb->ip_summed = CHECKSUM_NONE;
	179
	180	spin_lock(&x->lock);
	181
1da177e4 LT	182	/* If integrity check is required, do this. */
1da177e4 LT	183	if (esp->auth.icv_full_len) {
07d4ee58	184	u8 sum[alen];
1da177e4	185
07d4ee58 HX	186	err = esp_mac_digest(esp, skb, 0, skb->len - alen);
07d4ee58 HX	187	if (err)
0ebea8ef	188	goto unlock;
07d4ee58 HX	189
07d4ee58 HX	190	if (skb_copy_bits(skb, skb->len - alen, sum, alen))
1da177e4 LT	191	BUG();
1da177e4 LT	192
07d4ee58	193	if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
668dc8af	194	err = -EBADMSG;
0ebea8ef	195	goto unlock;
1da177e4 LT	196	}
	197	}
	198
87bdc48d	199	esph = (struct ip_esp_hdr *)skb->data;
1da177e4 LT	200
	201	/* Get ivec. This can be wrong, check against another impls. */
	202	if (esp->conf.ivlen)
6b7326c8	203	crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
1da177e4	204
4bf05ece	205	sg = &esp->sgbuf[0];
1da177e4	206
4bf05ece	207	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
668dc8af	208	err = -ENOMEM;
4bf05ece HX	209	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
4bf05ece HX	210	if (!sg)
0ebea8ef	211	goto unlock;
4bf05ece	212	}
ed0e7e0c	213	sg_init_table(sg, nfrags);
51c739d1 DM	214	skb_to_sgvec(skb, sg,
	215	sizeof(*esph) + esp->conf.ivlen,
	216	elen);
6b7326c8	217	err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
4bf05ece HX	218	if (unlikely(sg != &esp->sgbuf[0]))
4bf05ece HX	219	kfree(sg);
0ebea8ef HX	220
	221	unlock:
	222	spin_unlock(&x->lock);
	223
6b7326c8	224	if (unlikely(err))
668dc8af	225	goto out;
1da177e4	226
4bf05ece HX	227	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
4bf05ece HX	228	BUG();
1da177e4	229
668dc8af	230	err = -EINVAL;
4bf05ece HX	231	padlen = nexthdr[0];
	232	if (padlen+2 >= elen)
	233	goto out;
1da177e4	234
e905a9ed	235	/* ... check padding bits here. Silly. :-) */
1da177e4	236
2017a72c TG	237	/* RFC4303: Drop dummy packets without any error */
	238	if (nexthdr[1] == IPPROTO_NONE)
	239	goto out;
	240
eddc9ec5	241	iph = ip_hdr(skb);
31a4ab93 HX	242	ihl = iph->ihl * 4;
31a4ab93 HX	243
752c1f4c HX	244	if (x->encap) {
752c1f4c HX	245	struct xfrm_encap_tmpl *encap = x->encap;
d56f90a7	246	struct udphdr uh = (void )(skb_network_header(skb) + ihl);
752c1f4c HX	247
	248	/*
	249	* 1) if the NAT-T peer's IP or port changed then
	250	* advertize the change to the keying daemon.
	251	* This is an inbound SA, so just compare
	252	* SRC ports.
	253	*/
	254	if (iph->saddr != x->props.saddr.a4 \|\|
	255	uh->source != encap->encap_sport) {
	256	xfrm_address_t ipaddr;
	257
	258	ipaddr.a4 = iph->saddr;
	259	km_new_mapping(x, &ipaddr, uh->source);
e905a9ed	260
752c1f4c HX	261	/* XXX: perhaps add an extra
	262	* policy check here, to see
	263	* if we should allow or
	264	* reject a packet from a
	265	* different source
	266	* address/port.
	267	*/
1da177e4	268	}
e905a9ed	269
752c1f4c HX	270	/*
	271	* 2) ignore UDP/TCP checksums in case
	272	* of NAT-T in Transport Mode, or
	273	* perform other post-processing fixes
	274	* as per draft-ietf-ipsec-udp-encaps-06,
	275	* section 3.1.2
	276	*/
8bd17075	277	if (x->props.mode == XFRM_MODE_TRANSPORT)
752c1f4c	278	skb->ip_summed = CHECKSUM_UNNECESSARY;
1da177e4 LT	279	}
1da177e4 LT	280
4bf05ece	281	pskb_trim(skb, skb->len - alen - padlen - 2);
967b05f6 ACM	282	__skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
967b05f6 ACM	283	skb_set_transport_header(skb, -ihl);
4bf05ece	284
631a6698	285	return nexthdr[1];
1da177e4 LT	286
1da177e4 LT	287	out:
668dc8af	288	return err;
1da177e4 LT	289	}
1da177e4 LT	290
c5c25238	291	static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
1da177e4 LT	292	{
1da177e4 LT	293	struct esp_data *esp = x->data;
6b7326c8	294	u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
c5c25238 PM	295	u32 align = max_t(u32, blksize, esp->conf.padlen);
	296	u32 rem;
	297
	298	mtu -= x->props.header_len + esp->auth.icv_trunc_len;
	299	rem = mtu & (align - 1);
	300	mtu &= ~(align - 1);
0a69452c DB	301
	302	switch (x->props.mode) {
	303	case XFRM_MODE_TUNNEL:
0a69452c DB	304	break;
	305	default:
	306	case XFRM_MODE_TRANSPORT:
	307	/* The worst case */
c5c25238 PM	308	mtu -= blksize - 4;
c5c25238 PM	309	mtu += min_t(u32, blksize - 4, rem);
0a69452c DB	310	break;
0a69452c DB	311	case XFRM_MODE_BEET:
e905a9ed	312	/* The worst case. */
c5c25238	313	mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
0a69452c	314	break;
1da177e4	315	}
0a69452c	316
c5c25238	317	return mtu - 2;
1da177e4 LT	318	}
	319
	320	static void esp4_err(struct sk_buff *skb, u32 info)
	321	{
	322	struct iphdr iph = (struct iphdr)skb->data;
	323	struct ip_esp_hdr esph = (struct ip_esp_hdr)(skb->data+(iph->ihl<<2));
	324	struct xfrm_state *x;
	325
88c7664f ACM	326	if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH \|\|
88c7664f ACM	327	icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
1da177e4 LT	328	return;
	329
	330	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	331	if (!x)
	332	return;
64ce2073 PM	333	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
64ce2073 PM	334	ntohl(esph->spi), ntohl(iph->daddr));
1da177e4 LT	335	xfrm_state_put(x);
	336	}
	337
	338	static void esp_destroy(struct xfrm_state *x)
	339	{
	340	struct esp_data *esp = x->data;
	341
	342	if (!esp)
	343	return;
	344
6b7326c8	345	crypto_free_blkcipher(esp->conf.tfm);
573dbd95 JJ	346	esp->conf.tfm = NULL;
	347	kfree(esp->conf.ivec);
	348	esp->conf.ivec = NULL;
07d4ee58	349	crypto_free_hash(esp->auth.tfm);
573dbd95 JJ	350	esp->auth.tfm = NULL;
	351	kfree(esp->auth.work_icv);
	352	esp->auth.work_icv = NULL;
1da177e4 LT	353	kfree(esp);
	354	}
	355
72cb6962	356	static int esp_init_state(struct xfrm_state *x)
1da177e4 LT	357	{
1da177e4 LT	358	struct esp_data *esp = NULL;
6b7326c8	359	struct crypto_blkcipher *tfm;
c5c25238	360	u32 align;
1da177e4	361
1da177e4 LT	362	if (x->ealg == NULL)
	363	goto error;
	364
0da974f4	365	esp = kzalloc(sizeof(*esp), GFP_KERNEL);
1da177e4 LT	366	if (esp == NULL)
	367	return -ENOMEM;
	368
1da177e4 LT	369	if (x->aalg) {
1da177e4 LT	370	struct xfrm_algo_desc *aalg_desc;
07d4ee58	371	struct crypto_hash *hash;
1da177e4	372
07d4ee58 HX	373	hash = crypto_alloc_hash(x->aalg->alg_name, 0,
	374	CRYPTO_ALG_ASYNC);
	375	if (IS_ERR(hash))
	376	goto error;
	377
	378	esp->auth.tfm = hash;
4b7137ff HX	379	if (crypto_hash_setkey(hash, x->aalg->alg_key,
4b7137ff HX	380	(x->aalg->alg_key_len + 7) / 8))
1da177e4	381	goto error;
1da177e4 LT	382
	383	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	384	BUG_ON(!aalg_desc);
	385
	386	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
07d4ee58	387	crypto_hash_digestsize(hash)) {
64ce2073 PM	388	NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
64ce2073 PM	389	x->aalg->alg_name,
07d4ee58	390	crypto_hash_digestsize(hash),
64ce2073	391	aalg_desc->uinfo.auth.icv_fullbits/8);
1da177e4 LT	392	goto error;
	393	}
	394
	395	esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	396	esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	397
	398	esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
	399	if (!esp->auth.work_icv)
	400	goto error;
	401	}
4b7137ff	402
6b7326c8 HX	403	tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
6b7326c8 HX	404	if (IS_ERR(tfm))
1da177e4	405	goto error;
6b7326c8 HX	406	esp->conf.tfm = tfm;
6b7326c8 HX	407	esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
1da177e4 LT	408	esp->conf.padlen = 0;
	409	if (esp->conf.ivlen) {
	410	esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
	411	if (unlikely(esp->conf.ivec == NULL))
	412	goto error;
e4bec827	413	esp->conf.ivinitted = 0;
1da177e4	414	}
4b7137ff HX	415	if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
4b7137ff HX	416	(x->ealg->alg_key_len + 7) / 8))
1da177e4 LT	417	goto error;
1da177e4 LT	418	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
7e49e6de	419	if (x->props.mode == XFRM_MODE_TUNNEL)
1da177e4	420	x->props.header_len += sizeof(struct iphdr);
ac758e3c PM	421	else if (x->props.mode == XFRM_MODE_BEET)
ac758e3c PM	422	x->props.header_len += IPV4_BEET_PHMAXLEN;
1da177e4 LT	423	if (x->encap) {
	424	struct xfrm_encap_tmpl *encap = x->encap;
	425
	426	switch (encap->encap_type) {
	427	default:
	428	goto error;
	429	case UDP_ENCAP_ESPINUDP:
	430	x->props.header_len += sizeof(struct udphdr);
	431	break;
	432	case UDP_ENCAP_ESPINUDP_NON_IKE:
	433	x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
	434	break;
	435	}
	436	}
	437	x->data = esp;
c5c25238 PM	438	align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
	439	if (esp->conf.padlen)
	440	align = max_t(u32, align, esp->conf.padlen);
	441	x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len;
1da177e4 LT	442	return 0;
	443
	444	error:
	445	x->data = esp;
	446	esp_destroy(x);
	447	x->data = NULL;
	448	return -EINVAL;
	449	}
	450
	451	static struct xfrm_type esp_type =
	452	{
	453	.description = "ESP4",
	454	.owner = THIS_MODULE,
	455	.proto = IPPROTO_ESP,
436a0a40	456	.flags = XFRM_TYPE_REPLAY_PROT,
1da177e4 LT	457	.init_state = esp_init_state,
1da177e4 LT	458	.destructor = esp_destroy,
c5c25238	459	.get_mtu = esp4_get_mtu,
1da177e4	460	.input = esp_input,
1da177e4 LT	461	.output = esp_output
	462	};
	463
	464	static struct net_protocol esp4_protocol = {
	465	.handler = xfrm4_rcv,
	466	.err_handler = esp4_err,
	467	.no_policy = 1,
	468	};
	469
	470	static int __init esp4_init(void)
	471	{
1da177e4 LT	472	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
	473	printk(KERN_INFO "ip esp init: can't add xfrm type\n");
	474	return -EAGAIN;
	475	}
	476	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
	477	printk(KERN_INFO "ip esp init: can't add protocol\n");
	478	xfrm_unregister_type(&esp_type, AF_INET);
	479	return -EAGAIN;
	480	}
	481	return 0;
	482	}
	483
	484	static void __exit esp4_fini(void)
	485	{
	486	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
	487	printk(KERN_INFO "ip esp close: can't remove protocol\n");
	488	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
	489	printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
	490	}
	491
	492	module_init(esp4_init);
	493	module_exit(esp4_fini);
	494	MODULE_LICENSE("GPL");
d3d6dd3a	495	MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);