[mirror_ubuntu-focal-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 <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_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;

	/* 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 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;

	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
	1	#include <linux/err.h>
	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>
	8	#include <linux/kernel.h>
	9	#include <linux/pfkeyv2.h>
	10	#include <linux/random.h>
	11	#include <net/icmp.h>
	12	#include <net/protocol.h>
	13	#include <net/udp.h>
	14
	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;
	20	struct crypto_blkcipher *tfm;
	21	struct blkcipher_desc desc;
	22	struct esp_data *esp;
	23	struct sk_buff *trailer;
	24	u8 *tail;
	25	int blksize;
	26	int clen;
	27	int alen;
	28	int nfrags;
	29
	30	/* Strip IP+ESP header. */
	31	__skb_pull(skb, skb_transport_offset(skb));
	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;
	42	desc.tfm = tfm;
	43	desc.flags = 0;
	44	blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
	45	clen = ALIGN(clen + 2, blksize);
	46	if (esp->conf.padlen)
	47	clen = ALIGN(clen, esp->conf.padlen);
	48
	49	if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
	50	goto error;
	51
	52	/* Fill padding... */
	53	tail = skb_tail_pointer(trailer);
	54	do {
	55	int i;
	56	for (i=0; i<clen-skb->len - 2; i++)
	57	tail[i] = i + 1;
	58	} while (0);
	59	tail[clen - skb->len - 2] = (clen - skb->len) - 2;
	60	pskb_put(skb, trailer, clen - skb->len);
	61
	62	__skb_push(skb, -skb_network_offset(skb));
	63	top_iph = ip_hdr(skb);
	64	esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
	65	top_iph->ihl * 4);
	66	top_iph->tot_len = htons(skb->len + alen);
	67	*(skb_tail_pointer(trailer) - 1) = top_iph->protocol;
	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;
	73	__be32 *udpdata32;
	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:
	87	udpdata32 = (__be32 *)(uh + 1);
	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(XFRM_SKB_CB(skb)->seq);
	99
	100	if (esp->conf.ivlen) {
	101	if (unlikely(!esp->conf.ivinitted)) {
	102	get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	103	esp->conf.ivinitted = 1;
	104	}
	105	crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
	106	}
	107
	108	do {
	109	struct scatterlist *sg = &esp->sgbuf[0];
	110
	111	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	112	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	113	if (!sg)
	114	goto error;
	115	}
	116	skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
	117	err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
	118	if (unlikely(sg != &esp->sgbuf[0]))
	119	kfree(sg);
	120	} while (0);
	121
	122	if (unlikely(err))
	123	goto error;
	124
	125	if (esp->conf.ivlen) {
	126	memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
	127	crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
	128	}
	129
	130	if (esp->auth.icv_full_len) {
	131	err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
	132	sizeof(*esph) + esp->conf.ivlen + clen);
	133	memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
	134	}
	135
	136	ip_send_check(top_iph);
	137
	138	error:
	139	return err;
	140	}
	141
	142	/*
	143	* Note: detecting truncated vs. non-truncated authentication data is very
	144	* expensive, so we only support truncated data, which is the recommended
	145	* and common case.
	146	*/
	147	static int esp_input(struct xfrm_state x, struct sk_buff skb)
	148	{
	149	struct iphdr *iph;
	150	struct ip_esp_hdr *esph;
	151	struct esp_data *esp = x->data;
	152	struct crypto_blkcipher *tfm = esp->conf.tfm;
	153	struct blkcipher_desc desc = { .tfm = tfm };
	154	struct sk_buff *trailer;
	155	int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
	156	int alen = esp->auth.icv_trunc_len;
	157	int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
	158	int nfrags;
	159	int ihl;
	160	u8 nexthdr[2];
	161	struct scatterlist *sg;
	162	int padlen;
	163	int err;
	164
	165	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
	166	goto out;
	167
	168	if (elen <= 0 \|\| (elen & (blksize-1)))
	169	goto out;
	170
	171	/* If integrity check is required, do this. */
	172	if (esp->auth.icv_full_len) {
	173	u8 sum[alen];
	174
	175	err = esp_mac_digest(esp, skb, 0, skb->len - alen);
	176	if (err)
	177	goto out;
	178
	179	if (skb_copy_bits(skb, skb->len - alen, sum, alen))
	180	BUG();
	181
	182	if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
	183	x->stats.integrity_failed++;
	184	goto out;
	185	}
	186	}
	187
	188	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
	189	goto out;
	190
	191	skb->ip_summed = CHECKSUM_NONE;
	192
	193	esph = (struct ip_esp_hdr*)skb->data;
	194
	195	/* Get ivec. This can be wrong, check against another impls. */
	196	if (esp->conf.ivlen)
	197	crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
	198
	199	sg = &esp->sgbuf[0];
	200
	201	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	202	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	203	if (!sg)
	204	goto out;
	205	}
	206	skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
	207	err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
	208	if (unlikely(sg != &esp->sgbuf[0]))
	209	kfree(sg);
	210	if (unlikely(err))
	211	return err;
	212
	213	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
	214	BUG();
	215
	216	padlen = nexthdr[0];
	217	if (padlen+2 >= elen)
	218	goto out;
	219
	220	/* ... check padding bits here. Silly. :-) */
	221
	222	iph = ip_hdr(skb);
	223	ihl = iph->ihl * 4;
	224
	225	if (x->encap) {
	226	struct xfrm_encap_tmpl *encap = x->encap;
	227	struct udphdr uh = (void )(skb_network_header(skb) + ihl);
	228
	229	/*
	230	* 1) if the NAT-T peer's IP or port changed then
	231	* advertize the change to the keying daemon.
	232	* This is an inbound SA, so just compare
	233	* SRC ports.
	234	*/
	235	if (iph->saddr != x->props.saddr.a4 \|\|
	236	uh->source != encap->encap_sport) {
	237	xfrm_address_t ipaddr;
	238
	239	ipaddr.a4 = iph->saddr;
	240	km_new_mapping(x, &ipaddr, uh->source);
	241
	242	/* XXX: perhaps add an extra
	243	* policy check here, to see
	244	* if we should allow or
	245	* reject a packet from a
	246	* different source
	247	* address/port.
	248	*/
	249	}
	250
	251	/*
	252	* 2) ignore UDP/TCP checksums in case
	253	* of NAT-T in Transport Mode, or
	254	* perform other post-processing fixes
	255	* as per draft-ietf-ipsec-udp-encaps-06,
	256	* section 3.1.2
	257	*/
	258	if (x->props.mode == XFRM_MODE_TRANSPORT \|\|
	259	x->props.mode == XFRM_MODE_BEET)
	260	skb->ip_summed = CHECKSUM_UNNECESSARY;
	261	}
	262
	263	iph->protocol = nexthdr[1];
	264	pskb_trim(skb, skb->len - alen - padlen - 2);
	265	__skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
	266	skb_set_transport_header(skb, -ihl);
	267
	268	return 0;
	269
	270	out:
	271	return -EINVAL;
	272	}
	273
	274	static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
	275	{
	276	struct esp_data *esp = x->data;
	277	u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
	278	u32 align = max_t(u32, blksize, esp->conf.padlen);
	279	u32 rem;
	280
	281	mtu -= x->props.header_len + esp->auth.icv_trunc_len;
	282	rem = mtu & (align - 1);
	283	mtu &= ~(align - 1);
	284
	285	switch (x->props.mode) {
	286	case XFRM_MODE_TUNNEL:
	287	break;
	288	default:
	289	case XFRM_MODE_TRANSPORT:
	290	/* The worst case */
	291	mtu -= blksize - 4;
	292	mtu += min_t(u32, blksize - 4, rem);
	293	break;
	294	case XFRM_MODE_BEET:
	295	/* The worst case. */
	296	mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
	297	break;
	298	}
	299
	300	return mtu - 2;
	301	}
	302
	303	static void esp4_err(struct sk_buff *skb, u32 info)
	304	{
	305	struct iphdr iph = (struct iphdr)skb->data;
	306	struct ip_esp_hdr esph = (struct ip_esp_hdr)(skb->data+(iph->ihl<<2));
	307	struct xfrm_state *x;
	308
	309	if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH \|\|
	310	icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
	311	return;
	312
	313	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	314	if (!x)
	315	return;
	316	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
	317	ntohl(esph->spi), ntohl(iph->daddr));
	318	xfrm_state_put(x);
	319	}
	320
	321	static void esp_destroy(struct xfrm_state *x)
	322	{
	323	struct esp_data *esp = x->data;
	324
	325	if (!esp)
	326	return;
	327
	328	crypto_free_blkcipher(esp->conf.tfm);
	329	esp->conf.tfm = NULL;
	330	kfree(esp->conf.ivec);
	331	esp->conf.ivec = NULL;
	332	crypto_free_hash(esp->auth.tfm);
	333	esp->auth.tfm = NULL;
	334	kfree(esp->auth.work_icv);
	335	esp->auth.work_icv = NULL;
	336	kfree(esp);
	337	}
	338
	339	static int esp_init_state(struct xfrm_state *x)
	340	{
	341	struct esp_data *esp = NULL;
	342	struct crypto_blkcipher *tfm;
	343	u32 align;
	344
	345	if (x->ealg == NULL)
	346	goto error;
	347
	348	esp = kzalloc(sizeof(*esp), GFP_KERNEL);
	349	if (esp == NULL)
	350	return -ENOMEM;
	351
	352	if (x->aalg) {
	353	struct xfrm_algo_desc *aalg_desc;
	354	struct crypto_hash *hash;
	355
	356	hash = crypto_alloc_hash(x->aalg->alg_name, 0,
	357	CRYPTO_ALG_ASYNC);
	358	if (IS_ERR(hash))
	359	goto error;
	360
	361	esp->auth.tfm = hash;
	362	if (crypto_hash_setkey(hash, x->aalg->alg_key,
	363	(x->aalg->alg_key_len + 7) / 8))
	364	goto error;
	365
	366	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	367	BUG_ON(!aalg_desc);
	368
	369	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
	370	crypto_hash_digestsize(hash)) {
	371	NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
	372	x->aalg->alg_name,
	373	crypto_hash_digestsize(hash),
	374	aalg_desc->uinfo.auth.icv_fullbits/8);
	375	goto error;
	376	}
	377
	378	esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	379	esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	380
	381	esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
	382	if (!esp->auth.work_icv)
	383	goto error;
	384	}
	385
	386	tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
	387	if (IS_ERR(tfm))
	388	goto error;
	389	esp->conf.tfm = tfm;
	390	esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
	391	esp->conf.padlen = 0;
	392	if (esp->conf.ivlen) {
	393	esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
	394	if (unlikely(esp->conf.ivec == NULL))
	395	goto error;
	396	esp->conf.ivinitted = 0;
	397	}
	398	if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
	399	(x->ealg->alg_key_len + 7) / 8))
	400	goto error;
	401	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
	402	if (x->props.mode == XFRM_MODE_TUNNEL)
	403	x->props.header_len += sizeof(struct iphdr);
	404	else if (x->props.mode == XFRM_MODE_BEET)
	405	x->props.header_len += IPV4_BEET_PHMAXLEN;
	406	if (x->encap) {
	407	struct xfrm_encap_tmpl *encap = x->encap;
	408
	409	switch (encap->encap_type) {
	410	default:
	411	goto error;
	412	case UDP_ENCAP_ESPINUDP:
	413	x->props.header_len += sizeof(struct udphdr);
	414	break;
	415	case UDP_ENCAP_ESPINUDP_NON_IKE:
	416	x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
	417	break;
	418	}
	419	}
	420	x->data = esp;
	421	align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
	422	if (esp->conf.padlen)
	423	align = max_t(u32, align, esp->conf.padlen);
	424	x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len;
	425	return 0;
	426
	427	error:
	428	x->data = esp;
	429	esp_destroy(x);
	430	x->data = NULL;
	431	return -EINVAL;
	432	}
	433
	434	static struct xfrm_type esp_type =
	435	{
	436	.description = "ESP4",
	437	.owner = THIS_MODULE,
	438	.proto = IPPROTO_ESP,
	439	.flags = XFRM_TYPE_REPLAY_PROT,
	440	.init_state = esp_init_state,
	441	.destructor = esp_destroy,
	442	.get_mtu = esp4_get_mtu,
	443	.input = esp_input,
	444	.output = esp_output
	445	};
	446
	447	static struct net_protocol esp4_protocol = {
	448	.handler = xfrm4_rcv,
	449	.err_handler = esp4_err,
	450	.no_policy = 1,
	451	};
	452
	453	static int __init esp4_init(void)
	454	{
	455	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
	456	printk(KERN_INFO "ip esp init: can't add xfrm type\n");
	457	return -EAGAIN;
	458	}
	459	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
	460	printk(KERN_INFO "ip esp init: can't add protocol\n");
	461	xfrm_unregister_type(&esp_type, AF_INET);
	462	return -EAGAIN;
	463	}
	464	return 0;
	465	}
	466
	467	static void __exit esp4_fini(void)
	468	{
	469	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
	470	printk(KERN_INFO "ip esp close: can't remove protocol\n");
	471	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
	472	printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
	473	}
	474
	475	module_init(esp4_init);
	476	module_exit(esp4_fini);
	477	MODULE_LICENSE("GPL");
	478	MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);