[mirror_ubuntu-bionic-kernel.git] / net / ipv4 / esp4.c

#include <linux/config.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>

/* decapsulation data for use when post-processing */
struct esp_decap_data {
	xfrm_address_t	saddr;
	__u16		sport;
	__u8		proto;
};

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);

	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 xfrm_decap_state *decap, 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 encap_len = 0;

	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;
	iph = skb->nh.iph;

	/* 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));

        {
		u8 nexthdr[2];
		struct scatterlist *sg = &esp->sgbuf[0];
		u8 workbuf[60];
		int padlen;

		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. :-) */ 

		if (x->encap && decap && decap->decap_type) {
			struct esp_decap_data *encap_data;
			struct udphdr *uh = (struct udphdr *) (iph+1);

			encap_data = (struct esp_decap_data *) (decap->decap_data);
			encap_data->proto = 0;

			switch (decap->decap_type) {
			case UDP_ENCAP_ESPINUDP:
			case UDP_ENCAP_ESPINUDP_NON_IKE:
				encap_data->proto = AF_INET;
				encap_data->saddr.a4 = iph->saddr;
				encap_data->sport = uh->source;
				encap_len = (void*)esph - (void*)uh;
				break;

			default:
				goto out;
			}
		}

		iph->protocol = nexthdr[1];
		pskb_trim(skb, skb->len - alen - padlen - 2);
		memcpy(workbuf, skb->nh.raw, iph->ihl*4);
		skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen);
		skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
		memcpy(skb->nh.raw, workbuf, iph->ihl*4);
		skb->nh.iph->tot_len = htons(skb->len);
	}

	return 0;

out:
	return -EINVAL;
}

static int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
{
  
	if (x->encap) {
		struct xfrm_encap_tmpl *encap;
		struct esp_decap_data *decap_data;

		encap = x->encap;
		decap_data = (struct esp_decap_data *)(decap->decap_data);

		/* first, make sure that the decap type == the encap type */
		if (encap->encap_type != decap->decap_type)
			return -EINVAL;

		switch (encap->encap_type) {
		default:
		case UDP_ENCAP_ESPINUDP:
		case UDP_ENCAP_ESPINUDP_NON_IKE:
			/*
			 * 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 (decap_data->proto == AF_INET &&
			    (decap_data->saddr.a4 != x->props.saddr.a4 ||
			     decap_data->sport != encap->encap_sport)) {
				xfrm_address_t ipaddr;

				ipaddr.a4 = decap_data->saddr.a4;
				km_new_mapping(x, &ipaddr, decap_data->sport);
					
				/* 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;

			break;
		}
	}
	return 0;
}

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 = kmalloc(sizeof(*esp), GFP_KERNEL);
	if (esp == NULL)
		return -ENOMEM;

	memset(esp, 0, sizeof(*esp));

	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,
	.post_input	= esp_post_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)
{
	struct xfrm_decap_state decap;

	if (sizeof(struct esp_decap_data)  >
	    sizeof(decap.decap_data)) {
		extern void decap_data_too_small(void);

		decap_data_too_small();
	}

	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/config.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>
a02a6422	8	#include <linux/kernel.h>
1da177e4 LT	9	#include <linux/pfkeyv2.h>
	10	#include <linux/random.h>
	11	#include <net/icmp.h>
14c85021	12	#include <net/protocol.h>
1da177e4 LT	13	#include <net/udp.h>
	14
	15	/* decapsulation data for use when post-processing */
	16	struct esp_decap_data {
	17	xfrm_address_t saddr;
	18	__u16 sport;
	19	__u8 proto;
	20	};
	21
	22	static int esp_output(struct xfrm_state x, struct sk_buff skb)
	23	{
	24	int err;
	25	struct iphdr *top_iph;
	26	struct ip_esp_hdr *esph;
	27	struct crypto_tfm *tfm;
	28	struct esp_data *esp;
	29	struct sk_buff *trailer;
	30	int blksize;
	31	int clen;
	32	int alen;
	33	int nfrags;
	34
	35	/* Strip IP+ESP header. */
	36	__skb_pull(skb, skb->h.raw - skb->data);
	37	/* Now skb is pure payload to encrypt */
	38
	39	err = -ENOMEM;
	40
	41	/* Round to block size */
	42	clen = skb->len;
	43
	44	esp = x->data;
	45	alen = esp->auth.icv_trunc_len;
	46	tfm = esp->conf.tfm;
a02a6422 HX	47	blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4);
a02a6422 HX	48	clen = ALIGN(clen + 2, blksize);
1da177e4	49	if (esp->conf.padlen)
a02a6422	50	clen = ALIGN(clen, esp->conf.padlen);
1da177e4 LT	51
	52	if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
	53	goto error;
	54
	55	/* Fill padding... */
	56	do {
	57	int i;
	58	for (i=0; i<clen-skb->len - 2; i++)
	59	(u8)(trailer->tail + i) = i+1;
	60	} while (0);
	61	(u8)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
	62	pskb_put(skb, trailer, clen - skb->len);
	63
	64	__skb_push(skb, skb->data - skb->nh.raw);
	65	top_iph = skb->nh.iph;
	66	esph = (struct ip_esp_hdr )(skb->nh.raw + top_iph->ihl4);
	67	top_iph->tot_len = htons(skb->len + alen);
	68	(u8)(trailer->tail - 1) = top_iph->protocol;
	69
	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;
	74	u32 *udpdata32;
	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:
	88	udpdata32 = (u32 *)(uh + 1);
	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;
	99	esph->seq_no = htonl(++x->replay.oseq);
	100
	101	if (esp->conf.ivlen)
	102	crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
	103
	104	do {
	105	struct scatterlist *sg = &esp->sgbuf[0];
	106
	107	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	108	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	109	if (!sg)
	110	goto error;
	111	}
	112	skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
	113	crypto_cipher_encrypt(tfm, sg, sg, clen);
	114	if (unlikely(sg != &esp->sgbuf[0]))
115	kfree(sg);
116	} while (0);
117
118	if (esp->conf.ivlen) {
119	memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
120	crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
121	}
122
123	if (esp->auth.icv_full_len) {
124	esp->auth.icv(esp, skb, (u8*)esph-skb->data,
125	sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
126	pskb_put(skb, trailer, alen);
127	}
128
129	ip_send_check(top_iph);
130
131	err = 0;
132
133	error:
134	return err;
135	}
136
137	/*
138	* Note: detecting truncated vs. non-truncated authentication data is very
139	* expensive, so we only support truncated data, which is the recommended
140	* and common case.
141	*/
142	static int esp_input(struct xfrm_state x, struct xfrm_decap_state decap, struct sk_buff *skb)
143	{
144	struct iphdr *iph;
145	struct ip_esp_hdr *esph;
146	struct esp_data *esp = x->data;
147	struct sk_buff *trailer;
d4875b04	148	int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
1da177e4 LT	149	int alen = esp->auth.icv_trunc_len;
	150	int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
	151	int nfrags;
	152	int encap_len = 0;
	153
	154	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
	155	goto out;
	156
	157	if (elen <= 0 \|\| (elen & (blksize-1)))
	158	goto out;
	159
	160	/* If integrity check is required, do this. */
	161	if (esp->auth.icv_full_len) {
	162	u8 sum[esp->auth.icv_full_len];
	163	u8 sum1[alen];
	164
	165	esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
	166
	167	if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
	168	BUG();
	169
	170	if (unlikely(memcmp(sum, sum1, alen))) {
	171	x->stats.integrity_failed++;
	172	goto out;
	173	}
	174	}
	175
	176	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
	177	goto out;
	178
	179	skb->ip_summed = CHECKSUM_NONE;
	180
	181	esph = (struct ip_esp_hdr*)skb->data;
	182	iph = skb->nh.iph;
	183
	184	/* Get ivec. This can be wrong, check against another impls. */
	185	if (esp->conf.ivlen)
	186	crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
	187
	188	{
	189	u8 nexthdr[2];
	190	struct scatterlist *sg = &esp->sgbuf[0];
	191	u8 workbuf[60];
	192	int padlen;
	193
	194	if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
	195	sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
	196	if (!sg)
	197	goto out;
	198	}
	199	skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
	200	crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
	201	if (unlikely(sg != &esp->sgbuf[0]))
	202	kfree(sg);
	203
	204	if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
	205	BUG();
	206
	207	padlen = nexthdr[0];
	208	if (padlen+2 >= elen)
	209	goto out;
	210
	211	/* ... check padding bits here. Silly. :-) */
	212
213	if (x->encap && decap && decap->decap_type) {
214	struct esp_decap_data *encap_data;
215	struct udphdr uh = (struct udphdr ) (iph+1);
216
217	encap_data = (struct esp_decap_data *) (decap->decap_data);
218	encap_data->proto = 0;
219
220	switch (decap->decap_type) {
221	case UDP_ENCAP_ESPINUDP:
222	case UDP_ENCAP_ESPINUDP_NON_IKE:
223	encap_data->proto = AF_INET;
224	encap_data->saddr.a4 = iph->saddr;
225	encap_data->sport = uh->source;
226	encap_len = (void)esph - (void)uh;
227	break;
228
229	default:
230	goto out;
231	}
232	}
233
234	iph->protocol = nexthdr[1];
235	pskb_trim(skb, skb->len - alen - padlen - 2);
236	memcpy(workbuf, skb->nh.raw, iph->ihl*4);
237	skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen);
238	skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
239	memcpy(skb->nh.raw, workbuf, iph->ihl*4);
240	skb->nh.iph->tot_len = htons(skb->len);
241	}
242
243	return 0;
244
245	out:
246	return -EINVAL;
247	}
248
249	static int esp_post_input(struct xfrm_state x, struct xfrm_decap_state decap, struct sk_buff *skb)
250	{
251
252	if (x->encap) {
253	struct xfrm_encap_tmpl *encap;
254	struct esp_decap_data *decap_data;
255
256	encap = x->encap;
257	decap_data = (struct esp_decap_data *)(decap->decap_data);
258
259	/* first, make sure that the decap type == the encap type */
260	if (encap->encap_type != decap->decap_type)
261	return -EINVAL;
262
263	switch (encap->encap_type) {
264	default:
265	case UDP_ENCAP_ESPINUDP:
266	case UDP_ENCAP_ESPINUDP_NON_IKE:
267	/*
268	* 1) if the NAT-T peer's IP or port changed then
269	* advertize the change to the keying daemon.
270	* This is an inbound SA, so just compare
271	* SRC ports.
272	*/
273	if (decap_data->proto == AF_INET &&
274	(decap_data->saddr.a4 != x->props.saddr.a4 \|\|
275	decap_data->sport != encap->encap_sport)) {
276	xfrm_address_t ipaddr;
277
278	ipaddr.a4 = decap_data->saddr.a4;
279	km_new_mapping(x, &ipaddr, decap_data->sport);
280
281	/* XXX: perhaps add an extra
282	* policy check here, to see
283	* if we should allow or
284	* reject a packet from a
285	* different source
286	* address/port.
287	*/
288	}
289
290	/*
291	* 2) ignore UDP/TCP checksums in case
292	* of NAT-T in Transport Mode, or
293	* perform other post-processing fixes
294	* as per * draft-ietf-ipsec-udp-encaps-06,
295	* section 3.1.2
296	*/
297	if (!x->props.mode)
298	skb->ip_summed = CHECKSUM_UNNECESSARY;
299
300	break;
301	}
302	}
303	return 0;
304	}
305
306	static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
307	{
308	struct esp_data *esp = x->data;
d4875b04	309	u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
1da177e4 LT	310
1da177e4 LT	311	if (x->props.mode) {
a02a6422	312	mtu = ALIGN(mtu + 2, blksize);
1da177e4 LT	313	} else {
1da177e4 LT	314	/* The worst case. */
d4875b04	315	mtu = ALIGN(mtu + 2, 4) + blksize - 4;
1da177e4 LT	316	}
1da177e4 LT	317	if (esp->conf.padlen)
a02a6422	318	mtu = ALIGN(mtu, esp->conf.padlen);
1da177e4 LT	319
	320	return mtu + x->props.header_len + esp->auth.icv_trunc_len;
	321	}
	322
	323	static void esp4_err(struct sk_buff *skb, u32 info)
	324	{
	325	struct iphdr iph = (struct iphdr)skb->data;
	326	struct ip_esp_hdr esph = (struct ip_esp_hdr)(skb->data+(iph->ihl<<2));
	327	struct xfrm_state *x;
	328
	329	if (skb->h.icmph->type != ICMP_DEST_UNREACH \|\|
	330	skb->h.icmph->code != ICMP_FRAG_NEEDED)
	331	return;
	332
	333	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
	334	if (!x)
	335	return;
64ce2073 PM	336	NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
64ce2073 PM	337	ntohl(esph->spi), ntohl(iph->daddr));
1da177e4 LT	338	xfrm_state_put(x);
	339	}
	340
	341	static void esp_destroy(struct xfrm_state *x)
	342	{
	343	struct esp_data *esp = x->data;
	344
	345	if (!esp)
	346	return;
	347
573dbd95 JJ	348	crypto_free_tfm(esp->conf.tfm);
	349	esp->conf.tfm = NULL;
	350	kfree(esp->conf.ivec);
	351	esp->conf.ivec = NULL;
	352	crypto_free_tfm(esp->auth.tfm);
	353	esp->auth.tfm = NULL;
	354	kfree(esp->auth.work_icv);
	355	esp->auth.work_icv = NULL;
1da177e4 LT	356	kfree(esp);
	357	}
	358
72cb6962	359	static int esp_init_state(struct xfrm_state *x)
1da177e4 LT	360	{
	361	struct esp_data *esp = NULL;
	362
	363	/* null auth and encryption can have zero length keys */
	364	if (x->aalg) {
	365	if (x->aalg->alg_key_len > 512)
	366	goto error;
	367	}
	368	if (x->ealg == NULL)
	369	goto error;
	370
	371	esp = kmalloc(sizeof(*esp), GFP_KERNEL);
	372	if (esp == NULL)
	373	return -ENOMEM;
	374
	375	memset(esp, 0, sizeof(*esp));
	376
	377	if (x->aalg) {
	378	struct xfrm_algo_desc *aalg_desc;
	379
	380	esp->auth.key = x->aalg->alg_key;
	381	esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
	382	esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
	383	if (esp->auth.tfm == NULL)
	384	goto error;
	385	esp->auth.icv = esp_hmac_digest;
	386
	387	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	388	BUG_ON(!aalg_desc);
	389
	390	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
	391	crypto_tfm_alg_digestsize(esp->auth.tfm)) {
64ce2073 PM	392	NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
	393	x->aalg->alg_name,
	394	crypto_tfm_alg_digestsize(esp->auth.tfm),
	395	aalg_desc->uinfo.auth.icv_fullbits/8);
1da177e4 LT	396	goto error;
	397	}
	398
	399	esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	400	esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	401
	402	esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
	403	if (!esp->auth.work_icv)
	404	goto error;
	405	}
	406	esp->conf.key = x->ealg->alg_key;
	407	esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
	408	if (x->props.ealgo == SADB_EALG_NULL)
	409	esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
	410	else
	411	esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
	412	if (esp->conf.tfm == NULL)
	413	goto error;
	414	esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
	415	esp->conf.padlen = 0;
	416	if (esp->conf.ivlen) {
	417	esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
	418	if (unlikely(esp->conf.ivec == NULL))
	419	goto error;
	420	get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
	421	}
	422	if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len))
	423	goto error;
	424	x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
	425	if (x->props.mode)
	426	x->props.header_len += sizeof(struct iphdr);
	427	if (x->encap) {
	428	struct xfrm_encap_tmpl *encap = x->encap;
	429
	430	switch (encap->encap_type) {
	431	default:
	432	goto error;
	433	case UDP_ENCAP_ESPINUDP:
	434	x->props.header_len += sizeof(struct udphdr);
	435	break;
	436	case UDP_ENCAP_ESPINUDP_NON_IKE:
	437	x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
	438	break;
	439	}
	440	}
	441	x->data = esp;
	442	x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
	443	return 0;
	444
	445	error:
	446	x->data = esp;
	447	esp_destroy(x);
	448	x->data = NULL;
	449	return -EINVAL;
	450	}
	451
	452	static struct xfrm_type esp_type =
	453	{
	454	.description = "ESP4",
	455	.owner = THIS_MODULE,
	456	.proto = IPPROTO_ESP,
	457	.init_state = esp_init_state,
	458	.destructor = esp_destroy,
	459	.get_max_size = esp4_get_max_size,
460	.input = esp_input,
461	.post_input = esp_post_input,
462	.output = esp_output
463	};
464
465	static struct net_protocol esp4_protocol = {
466	.handler = xfrm4_rcv,
467	.err_handler = esp4_err,
468	.no_policy = 1,
469	};
470
471	static int __init esp4_init(void)
472	{
473	struct xfrm_decap_state decap;
474
36839836	475	if (sizeof(struct esp_decap_data) >
1da177e4 LT	476	sizeof(decap.decap_data)) {
	477	extern void decap_data_too_small(void);
	478
	479	decap_data_too_small();
	480	}
	481
	482	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
	483	printk(KERN_INFO "ip esp init: can't add xfrm type\n");
	484	return -EAGAIN;
	485	}
	486	if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
	487	printk(KERN_INFO "ip esp init: can't add protocol\n");
	488	xfrm_unregister_type(&esp_type, AF_INET);
	489	return -EAGAIN;
	490	}
	491	return 0;
	492	}
	493
	494	static void __exit esp4_fini(void)
	495	{
	496	if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
	497	printk(KERN_INFO "ip esp close: can't remove protocol\n");
	498	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
	499	printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
	500	}
	501
	502	module_init(esp4_init);
	503	module_exit(esp4_fini);
	504	MODULE_LICENSE("GPL");