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

#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_tfm *tfm;
	struct esp_data *esp;
	struct sk_buff *trailer;
	int blksize;
	int clen;
	int alen;
	int nfrags;

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

	err = -ENOMEM;

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

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

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

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

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

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

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

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

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

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

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

	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);
		crypto_cipher_encrypt(tfm, sg, sg, clen);
		if (unlikely(sg != &esp->sgbuf[0]))
			kfree(sg);
	} while (0);

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

	if (esp->auth.icv_full_len) {
		esp->auth.icv(esp, skb, (u8*)esph-skb->data,
		              sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
		pskb_put(skb, trailer, alen);
	}

	ip_send_check(top_iph);

	err = 0;

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 sk_buff *trailer;
	int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.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;

	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[esp->auth.icv_full_len];
		u8 sum1[alen];
		
		esp->auth.icv(esp, skb, 0, skb->len-alen, sum);

		if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
			BUG();

		if (unlikely(memcmp(sum, sum1, 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_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));

	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);
	crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
	if (unlikely(sg != &esp->sgbuf[0]))
		kfree(sg);

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

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

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

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

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

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

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

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

	return 0;

out:
	return -EINVAL;
}

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

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

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

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

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

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

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

	if (!esp)
		return;

	crypto_free_tfm(esp->conf.tfm);
	esp->conf.tfm = NULL;
	kfree(esp->conf.ivec);
	esp->conf.ivec = NULL;
	crypto_free_tfm(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;

	/* 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;

		esp->auth.key = x->aalg->alg_key;
		esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
		esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
		if (esp->auth.tfm == NULL)
			goto error;
		esp->auth.icv = esp_hmac_digest;

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

		if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
		    crypto_tfm_alg_digestsize(esp->auth.tfm)) {
			NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
				 x->aalg->alg_name,
				 crypto_tfm_alg_digestsize(esp->auth.tfm),
				 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;
	if (x->props.ealgo == SADB_EALG_NULL)
		esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
	else
		esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
	if (esp->conf.tfm == NULL)
		goto error;
	esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
	esp->conf.padlen = 0;
	if (esp->conf.ivlen) {
		esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
		if (unlikely(esp->conf.ivec == NULL))
			goto error;
		get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	}
	if (crypto_cipher_setkey(esp->conf.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)
		x->props.header_len += sizeof(struct iphdr);
	if (x->encap) {
		struct xfrm_encap_tmpl *encap = x->encap;

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

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

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

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

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

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

module_init(esp4_init);
module_exit(esp4_fini);
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	#include <linux/module.h>
	2	#include <net/ip.h>
	3	#include <net/xfrm.h>
	4	#include <net/esp.h>
	5	#include <asm/scatterlist.h>
	6	#include <linux/crypto.h>
a02a6422	7	#include <linux/kernel.h>
1da177e4 LT	8	#include <linux/pfkeyv2.h>
	9	#include <linux/random.h>
	10	#include <net/icmp.h>
14c85021	11	#include <net/protocol.h>
1da177e4 LT	12	#include <net/udp.h>
1da177e4 LT	13
1da177e4 LT	14	static int esp_output(struct xfrm_state x, struct sk_buff skb)
	15	{
	16	int err;
	17	struct iphdr *top_iph;
	18	struct ip_esp_hdr *esph;
	19	struct crypto_tfm *tfm;
	20	struct esp_data *esp;
	21	struct sk_buff *trailer;
	22	int blksize;
	23	int clen;
	24	int alen;
	25	int nfrags;
	26
	27	/* Strip IP+ESP header. */
	28	__skb_pull(skb, skb->h.raw - skb->data);
	29	/* Now skb is pure payload to encrypt */
	30
	31	err = -ENOMEM;
	32
	33	/* Round to block size */
	34	clen = skb->len;
	35
	36	esp = x->data;
	37	alen = esp->auth.icv_trunc_len;
	38	tfm = esp->conf.tfm;
a02a6422 HX	39	blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4);
a02a6422 HX	40	clen = ALIGN(clen + 2, blksize);
1da177e4	41	if (esp->conf.padlen)
a02a6422	42	clen = ALIGN(clen, esp->conf.padlen);
1da177e4 LT	43
	44	if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
	45	goto error;
	46
	47	/* Fill padding... */
	48	do {
	49	int i;
	50	for (i=0; i<clen-skb->len - 2; i++)
	51	(u8)(trailer->tail + i) = i+1;
	52	} while (0);
	53	(u8)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
	54	pskb_put(skb, trailer, clen - skb->len);
	55
	56	__skb_push(skb, skb->data - skb->nh.raw);
	57	top_iph = skb->nh.iph;
	58	esph = (struct ip_esp_hdr )(skb->nh.raw + top_iph->ihl4);
	59	top_iph->tot_len = htons(skb->len + alen);
	60	(u8)(trailer->tail - 1) = top_iph->protocol;
	61
	62	/* this is non-NULL only with UDP Encapsulation */
	63	if (x->encap) {
	64	struct xfrm_encap_tmpl *encap = x->encap;
	65	struct udphdr *uh;
	66	u32 *udpdata32;
	67
	68	uh = (struct udphdr *)esph;
	69	uh->source = encap->encap_sport;
	70	uh->dest = encap->encap_dport;
	71	uh->len = htons(skb->len + alen - top_iph->ihl*4);
	72	uh->check = 0;
	73
	74	switch (encap->encap_type) {
	75	default:
	76	case UDP_ENCAP_ESPINUDP:
	77	esph = (struct ip_esp_hdr *)(uh + 1);
	78	break;
	79	case UDP_ENCAP_ESPINUDP_NON_IKE:
	80	udpdata32 = (u32 *)(uh + 1);
	81	udpdata32[0] = udpdata32[1] = 0;
	82	esph = (struct ip_esp_hdr *)(udpdata32 + 2);
	83	break;
	84	}
	85
	86	top_iph->protocol = IPPROTO_UDP;
	87	} else
	88	top_iph->protocol = IPPROTO_ESP;
	89
	90	esph->spi = x->id.spi;
	91	esph->seq_no = htonl(++x->replay.oseq);
9500e8a8	92	xfrm_aevent_doreplay(x);
1da177e4 LT	93
	94	if (esp->conf.ivlen)
	95	crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
	96
	97	do {
	98	struct scatterlist *sg = &esp->sgbuf[0];
	99
	100	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	101	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	102	if (!sg)
	103	goto error;
	104	}
	105	skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
	106	crypto_cipher_encrypt(tfm, sg, sg, clen);
	107	if (unlikely(sg != &esp->sgbuf[0]))
	108	kfree(sg);
	109	} while (0);
	110
	111	if (esp->conf.ivlen) {
	112	memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
	113	crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
	114	}
	115
	116	if (esp->auth.icv_full_len) {
	117	esp->auth.icv(esp, skb, (u8*)esph-skb->data,
	118	sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
	119	pskb_put(skb, trailer, alen);
	120	}
	121
	122	ip_send_check(top_iph);
	123
	124	err = 0;
	125
	126	error:
	127	return err;
	128	}
	129
	130	/*
	131	* Note: detecting truncated vs. non-truncated authentication data is very
	132	* expensive, so we only support truncated data, which is the recommended
	133	* and common case.
	134	*/
e695633e	135	static int esp_input(struct xfrm_state x, struct sk_buff skb)
1da177e4 LT	136	{
	137	struct iphdr *iph;
	138	struct ip_esp_hdr *esph;
	139	struct esp_data *esp = x->data;
	140	struct sk_buff *trailer;
d4875b04	141	int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
1da177e4 LT	142	int alen = esp->auth.icv_trunc_len;
	143	int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
	144	int nfrags;
31a4ab93	145	int ihl;
4bf05ece HX	146	u8 nexthdr[2];
4bf05ece HX	147	struct scatterlist *sg;
4bf05ece	148	int padlen;
1da177e4 LT	149
	150	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
	151	goto out;
	152
	153	if (elen <= 0 \|\| (elen & (blksize-1)))
	154	goto out;
	155
	156	/* If integrity check is required, do this. */
	157	if (esp->auth.icv_full_len) {
	158	u8 sum[esp->auth.icv_full_len];
	159	u8 sum1[alen];
	160
	161	esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
	162
	163	if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
	164	BUG();
	165
	166	if (unlikely(memcmp(sum, sum1, alen))) {
	167	x->stats.integrity_failed++;
	168	goto out;
	169	}
	170	}
	171
	172	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
	173	goto out;
	174
	175	skb->ip_summed = CHECKSUM_NONE;
	176
	177	esph = (struct ip_esp_hdr*)skb->data;
1da177e4 LT	178
	179	/* Get ivec. This can be wrong, check against another impls. */
	180	if (esp->conf.ivlen)
	181	crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
	182
4bf05ece	183	sg = &esp->sgbuf[0];
1da177e4	184
4bf05ece HX	185	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	186	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	187	if (!sg)
	188	goto out;
	189	}
	190	skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
	191	crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
	192	if (unlikely(sg != &esp->sgbuf[0]))
	193	kfree(sg);
1da177e4	194
4bf05ece HX	195	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
4bf05ece HX	196	BUG();
1da177e4	197
4bf05ece HX	198	padlen = nexthdr[0];
	199	if (padlen+2 >= elen)
	200	goto out;
1da177e4	201
4bf05ece	202	/* ... check padding bits here. Silly. :-) */
1da177e4	203
31a4ab93 HX	204	iph = skb->nh.iph;
	205	ihl = iph->ihl * 4;
	206
752c1f4c HX	207	if (x->encap) {
752c1f4c HX	208	struct xfrm_encap_tmpl *encap = x->encap;
31a4ab93	209	struct udphdr uh = (void )(skb->nh.raw + ihl);
752c1f4c HX	210
	211	/*
	212	* 1) if the NAT-T peer's IP or port changed then
	213	* advertize the change to the keying daemon.
	214	* This is an inbound SA, so just compare
	215	* SRC ports.
	216	*/
	217	if (iph->saddr != x->props.saddr.a4 \|\|
	218	uh->source != encap->encap_sport) {
	219	xfrm_address_t ipaddr;
	220
	221	ipaddr.a4 = iph->saddr;
	222	km_new_mapping(x, &ipaddr, uh->source);
	223
	224	/* XXX: perhaps add an extra
	225	* policy check here, to see
	226	* if we should allow or
	227	* reject a packet from a
	228	* different source
	229	* address/port.
	230	*/
1da177e4	231	}
752c1f4c HX	232
	233	/*
	234	* 2) ignore UDP/TCP checksums in case
	235	* of NAT-T in Transport Mode, or
	236	* perform other post-processing fixes
	237	* as per draft-ietf-ipsec-udp-encaps-06,
	238	* section 3.1.2
	239	*/
	240	if (!x->props.mode)
	241	skb->ip_summed = CHECKSUM_UNNECESSARY;
1da177e4 LT	242	}
1da177e4 LT	243
4bf05ece HX	244	iph->protocol = nexthdr[1];
4bf05ece HX	245	pskb_trim(skb, skb->len - alen - padlen - 2);
31a4ab93	246	skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl;
4bf05ece	247
1da177e4 LT	248	return 0;
	249
	250	out:
	251	return -EINVAL;
	252	}
	253
1da177e4 LT	254	static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
	255	{
	256	struct esp_data *esp = x->data;
d4875b04	257	u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
1da177e4 LT	258
1da177e4 LT	259	if (x->props.mode) {
a02a6422	260	mtu = ALIGN(mtu + 2, blksize);
1da177e4 LT	261	} else {
1da177e4 LT	262	/* The worst case. */
d4875b04	263	mtu = ALIGN(mtu + 2, 4) + blksize - 4;
1da177e4 LT	264	}
1da177e4 LT	265	if (esp->conf.padlen)
a02a6422	266	mtu = ALIGN(mtu, esp->conf.padlen);
1da177e4 LT	267
	268	return mtu + x->props.header_len + esp->auth.icv_trunc_len;
	269	}
	270
	271	static void esp4_err(struct sk_buff *skb, u32 info)
	272	{
	273	struct iphdr iph = (struct iphdr)skb->data;
	274	struct ip_esp_hdr esph = (struct ip_esp_hdr)(skb->data+(iph->ihl<<2));
	275	struct xfrm_state *x;
	276
	277	if (skb->h.icmph->type != ICMP_DEST_UNREACH \|\|
	278	skb->h.icmph->code != ICMP_FRAG_NEEDED)
	279	return;
	280
	281	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	282	if (!x)
	283	return;
64ce2073 PM	284	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
64ce2073 PM	285	ntohl(esph->spi), ntohl(iph->daddr));
1da177e4 LT	286	xfrm_state_put(x);
	287	}
	288
	289	static void esp_destroy(struct xfrm_state *x)
	290	{
	291	struct esp_data *esp = x->data;
	292
	293	if (!esp)
	294	return;
	295
573dbd95 JJ	296	crypto_free_tfm(esp->conf.tfm);
	297	esp->conf.tfm = NULL;
	298	kfree(esp->conf.ivec);
	299	esp->conf.ivec = NULL;
	300	crypto_free_tfm(esp->auth.tfm);
	301	esp->auth.tfm = NULL;
	302	kfree(esp->auth.work_icv);
	303	esp->auth.work_icv = NULL;
1da177e4 LT	304	kfree(esp);
	305	}
	306
72cb6962	307	static int esp_init_state(struct xfrm_state *x)
1da177e4 LT	308	{
	309	struct esp_data *esp = NULL;
	310
	311	/* null auth and encryption can have zero length keys */
	312	if (x->aalg) {
	313	if (x->aalg->alg_key_len > 512)
	314	goto error;
	315	}
	316	if (x->ealg == NULL)
	317	goto error;
	318
0da974f4	319	esp = kzalloc(sizeof(*esp), GFP_KERNEL);
1da177e4 LT	320	if (esp == NULL)
	321	return -ENOMEM;
	322
1da177e4 LT	323	if (x->aalg) {
	324	struct xfrm_algo_desc *aalg_desc;
	325
	326	esp->auth.key = x->aalg->alg_key;
	327	esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
	328	esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
	329	if (esp->auth.tfm == NULL)
	330	goto error;
	331	esp->auth.icv = esp_hmac_digest;
	332
	333	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	334	BUG_ON(!aalg_desc);
	335
	336	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
	337	crypto_tfm_alg_digestsize(esp->auth.tfm)) {
64ce2073 PM	338	NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
	339	x->aalg->alg_name,
	340	crypto_tfm_alg_digestsize(esp->auth.tfm),
	341	aalg_desc->uinfo.auth.icv_fullbits/8);
1da177e4 LT	342	goto error;
	343	}
	344
	345	esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	346	esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	347
	348	esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
	349	if (!esp->auth.work_icv)
	350	goto error;
	351	}
	352	esp->conf.key = x->ealg->alg_key;
	353	esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
	354	if (x->props.ealgo == SADB_EALG_NULL)
	355	esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
	356	else
	357	esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
	358	if (esp->conf.tfm == NULL)
	359	goto error;
	360	esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
	361	esp->conf.padlen = 0;
	362	if (esp->conf.ivlen) {
	363	esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
	364	if (unlikely(esp->conf.ivec == NULL))
	365	goto error;
	366	get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	367	}
	368	if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len))
	369	goto error;
	370	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
	371	if (x->props.mode)
	372	x->props.header_len += sizeof(struct iphdr);
	373	if (x->encap) {
	374	struct xfrm_encap_tmpl *encap = x->encap;
	375
	376	switch (encap->encap_type) {
	377	default:
	378	goto error;
	379	case UDP_ENCAP_ESPINUDP:
	380	x->props.header_len += sizeof(struct udphdr);
	381	break;
	382	case UDP_ENCAP_ESPINUDP_NON_IKE:
	383	x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
	384	break;
	385	}
	386	}
	387	x->data = esp;
	388	x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
	389	return 0;
	390
	391	error:
	392	x->data = esp;
	393	esp_destroy(x);
	394	x->data = NULL;
	395	return -EINVAL;
	396	}
	397
	398	static struct xfrm_type esp_type =
	399	{
	400	.description = "ESP4",
	401	.owner = THIS_MODULE,
	402	.proto = IPPROTO_ESP,
	403	.init_state = esp_init_state,
	404	.destructor = esp_destroy,
	405	.get_max_size = esp4_get_max_size,
406	.input = esp_input,
1da177e4 LT	407	.output = esp_output
	408	};
	409
	410	static struct net_protocol esp4_protocol = {
	411	.handler = xfrm4_rcv,
	412	.err_handler = esp4_err,
	413	.no_policy = 1,
	414	};
	415
	416	static int __init esp4_init(void)
	417	{
1da177e4 LT	418	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
	419	printk(KERN_INFO "ip esp init: can't add xfrm type\n");
	420	return -EAGAIN;
	421	}
	422	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
	423	printk(KERN_INFO "ip esp init: can't add protocol\n");
	424	xfrm_unregister_type(&esp_type, AF_INET);
	425	return -EAGAIN;
	426	}
	427	return 0;
	428	}
	429
	430	static void __exit esp4_fini(void)
	431	{
	432	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
	433	printk(KERN_INFO "ip esp close: can't remove protocol\n");
	434	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
	435	printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
	436	}
	437
	438	module_init(esp4_init);
	439	module_exit(esp4_fini);
	440	MODULE_LICENSE("GPL");