1 files changed, 731 insertions, 0 deletions

diff --git a/kernel/net/ipv4/esp4.c b/kernel/net/ipv4/esp4.c
new file mode 100644
index 000000000..30b544f02
--- /dev/null
+++ b/kernel/net/ipv4/esp4.c
@@ -0,0 +1,731 @@
+#define pr_fmt(fmt) "IPsec: " fmt
+
+#include <crypto/aead.h>
+#include <crypto/authenc.h>
+#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/kernel.h>
+#include <linux/pfkeyv2.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/in6.h>
+#include <net/icmp.h>
+#include <net/protocol.h>
+#include <net/udp.h>
+
+struct esp_skb_cb {
+	struct xfrm_skb_cb xfrm;
+	void *tmp;
+};
+
+#define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
+
+static u32 esp4_get_mtu(struct xfrm_state *x, int mtu);
+
+/*
+ * Allocate an AEAD request structure with extra space for SG and IV.
+ *
+ * For alignment considerations the IV is placed at the front, followed
+ * by the request and finally the SG list.
+ *
+ * TODO: Use spare space in skb for this where possible.
+ */
+static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int seqhilen)
+{
+	unsigned int len;
+
+	len = seqhilen;
+
+	len += crypto_aead_ivsize(aead);
+
+	if (len) {
+		len += crypto_aead_alignmask(aead) &
+		       ~(crypto_tfm_ctx_alignment() - 1);
+		len = ALIGN(len, crypto_tfm_ctx_alignment());
+	}
+
+	len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead);
+	len = ALIGN(len, __alignof__(struct scatterlist));
+
+	len += sizeof(struct scatterlist) * nfrags;
+
+	return kmalloc(len, GFP_ATOMIC);
+}
+
+static inline __be32 *esp_tmp_seqhi(void *tmp)
+{
+	return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32));
+}
+static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen)
+{
+	return crypto_aead_ivsize(aead) ?
+	       PTR_ALIGN((u8 *)tmp + seqhilen,
+			 crypto_aead_alignmask(aead) + 1) : tmp + seqhilen;
+}
+
+static inline struct aead_givcrypt_request *esp_tmp_givreq(
+	struct crypto_aead *aead, u8 *iv)
+{
+	struct aead_givcrypt_request *req;
+
+	req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
+				crypto_tfm_ctx_alignment());
+	aead_givcrypt_set_tfm(req, aead);
+	return req;
+}
+
+static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
+{
+	struct aead_request *req;
+
+	req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
+				crypto_tfm_ctx_alignment());
+	aead_request_set_tfm(req, aead);
+	return req;
+}
+
+static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
+					     struct aead_request *req)
+{
+	return (void *)ALIGN((unsigned long)(req + 1) +
+			     crypto_aead_reqsize(aead),
+			     __alignof__(struct scatterlist));
+}
+
+static inline struct scatterlist *esp_givreq_sg(
+	struct crypto_aead *aead, struct aead_givcrypt_request *req)
+{
+	return (void *)ALIGN((unsigned long)(req + 1) +
+			     crypto_aead_reqsize(aead),
+			     __alignof__(struct scatterlist));
+}
+
+static void esp_output_done(struct crypto_async_request *base, int err)
+{
+	struct sk_buff *skb = base->data;
+
+	kfree(ESP_SKB_CB(skb)->tmp);
+	xfrm_output_resume(skb, err);
+}
+
+static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err;
+	struct ip_esp_hdr *esph;
+	struct crypto_aead *aead;
+	struct aead_givcrypt_request *req;
+	struct scatterlist *sg;
+	struct scatterlist *asg;
+	struct sk_buff *trailer;
+	void *tmp;
+	u8 *iv;
+	u8 *tail;
+	int blksize;
+	int clen;
+	int alen;
+	int plen;
+	int tfclen;
+	int nfrags;
+	int assoclen;
+	int sglists;
+	int seqhilen;
+	__be32 *seqhi;
+
+	/* skb is pure payload to encrypt */
+
+	aead = x->data;
+	alen = crypto_aead_authsize(aead);
+
+	tfclen = 0;
+	if (x->tfcpad) {
+		struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
+		u32 padto;
+
+		padto = min(x->tfcpad, esp4_get_mtu(x, dst->child_mtu_cached));
+		if (skb->len < padto)
+			tfclen = padto - skb->len;
+	}
+	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
+	clen = ALIGN(skb->len + 2 + tfclen, blksize);
+	plen = clen - skb->len - tfclen;
+
+	err = skb_cow_data(skb, tfclen + plen + alen, &trailer);
+	if (err < 0)
+		goto error;
+	nfrags = err;
+
+	assoclen = sizeof(*esph);
+	sglists = 1;
+	seqhilen = 0;
+
+	if (x->props.flags & XFRM_STATE_ESN) {
+		sglists += 2;
+		seqhilen += sizeof(__be32);
+		assoclen += seqhilen;
+	}
+
+	tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
+	if (!tmp) {
+		err = -ENOMEM;
+		goto error;
+	}
+
+	seqhi = esp_tmp_seqhi(tmp);
+	iv = esp_tmp_iv(aead, tmp, seqhilen);
+	req = esp_tmp_givreq(aead, iv);
+	asg = esp_givreq_sg(aead, req);
+	sg = asg + sglists;
+
+	/* Fill padding... */
+	tail = skb_tail_pointer(trailer);
+	if (tfclen) {
+		memset(tail, 0, tfclen);
+		tail += tfclen;
+	}
+	do {
+		int i;
+		for (i = 0; i < plen - 2; i++)
+			tail[i] = i + 1;
+	} while (0);
+	tail[plen - 2] = plen - 2;
+	tail[plen - 1] = *skb_mac_header(skb);
+	pskb_put(skb, trailer, clen - skb->len + alen);
+
+	skb_push(skb, -skb_network_offset(skb));
+	esph = ip_esp_hdr(skb);
+	*skb_mac_header(skb) = IPPROTO_ESP;
+
+	/* this is non-NULL only with UDP Encapsulation */
+	if (x->encap) {
+		struct xfrm_encap_tmpl *encap = x->encap;
+		struct udphdr *uh;
+		__be32 *udpdata32;
+		__be16 sport, dport;
+		int encap_type;
+
+		spin_lock_bh(&x->lock);
+		sport = encap->encap_sport;
+		dport = encap->encap_dport;
+		encap_type = encap->encap_type;
+		spin_unlock_bh(&x->lock);
+
+		uh = (struct udphdr *)esph;
+		uh->source = sport;
+		uh->dest = dport;
+		uh->len = htons(skb->len - skb_transport_offset(skb));
+		uh->check = 0;
+
+		switch (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.output.low);
+
+	sg_init_table(sg, nfrags);
+	skb_to_sgvec(skb, sg,
+		     esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
+		     clen + alen);
+
+	if ((x->props.flags & XFRM_STATE_ESN)) {
+		sg_init_table(asg, 3);
+		sg_set_buf(asg, &esph->spi, sizeof(__be32));
+		*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
+		sg_set_buf(asg + 1, seqhi, seqhilen);
+		sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
+	} else
+		sg_init_one(asg, esph, sizeof(*esph));
+
+	aead_givcrypt_set_callback(req, 0, esp_output_done, skb);
+	aead_givcrypt_set_crypt(req, sg, sg, clen, iv);
+	aead_givcrypt_set_assoc(req, asg, assoclen);
+	aead_givcrypt_set_giv(req, esph->enc_data,
+			      XFRM_SKB_CB(skb)->seq.output.low +
+			      ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32));
+
+	ESP_SKB_CB(skb)->tmp = tmp;
+	err = crypto_aead_givencrypt(req);
+	if (err == -EINPROGRESS)
+		goto error;
+
+	if (err == -EBUSY)
+		err = NET_XMIT_DROP;
+
+	kfree(tmp);
+
+error:
+	return err;
+}
+
+static int esp_input_done2(struct sk_buff *skb, int err)
+{
+	const struct iphdr *iph;
+	struct xfrm_state *x = xfrm_input_state(skb);
+	struct crypto_aead *aead = x->data;
+	int alen = crypto_aead_authsize(aead);
+	int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
+	int elen = skb->len - hlen;
+	int ihl;
+	u8 nexthdr[2];
+	int padlen;
+
+	kfree(ESP_SKB_CB(skb)->tmp);
+
+	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 + alen >= elen)
+		goto out;
+
+	/* ... check padding bits here. Silly. :-) */
+
+	iph = ip_hdr(skb);
+	ihl = iph->ihl * 4;
+
+	if (x->encap) {
+		struct xfrm_encap_tmpl *encap = x->encap;
+		struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
+
+		/*
+		 * 1) if the NAT-T peer's IP or port changed then
+		 *    advertize the change to the keying daemon.
+		 *    This is an inbound SA, so just compare
+		 *    SRC ports.
+		 */
+		if (iph->saddr != x->props.saddr.a4 ||
+		    uh->source != encap->encap_sport) {
+			xfrm_address_t ipaddr;
+
+			ipaddr.a4 = iph->saddr;
+			km_new_mapping(x, &ipaddr, uh->source);
+
+			/* XXX: perhaps add an extra
+			 * policy check here, to see
+			 * if we should allow or
+			 * reject a packet from a
+			 * different source
+			 * address/port.
+			 */
+		}
+
+		/*
+		 * 2) ignore UDP/TCP checksums in case
+		 *    of NAT-T in Transport Mode, or
+		 *    perform other post-processing fixes
+		 *    as per draft-ietf-ipsec-udp-encaps-06,
+		 *    section 3.1.2
+		 */
+		if (x->props.mode == XFRM_MODE_TRANSPORT)
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+	}
+
+	pskb_trim(skb, skb->len - alen - padlen - 2);
+	__skb_pull(skb, hlen);
+	if (x->props.mode == XFRM_MODE_TUNNEL)
+		skb_reset_transport_header(skb);
+	else
+		skb_set_transport_header(skb, -ihl);
+
+	err = nexthdr[1];
+
+	/* RFC4303: Drop dummy packets without any error */
+	if (err == IPPROTO_NONE)
+		err = -EINVAL;
+
+out:
+	return err;
+}
+
+static void esp_input_done(struct crypto_async_request *base, int err)
+{
+	struct sk_buff *skb = base->data;
+
+	xfrm_input_resume(skb, esp_input_done2(skb, 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 ip_esp_hdr *esph;
+	struct crypto_aead *aead = x->data;
+	struct aead_request *req;
+	struct sk_buff *trailer;
+	int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
+	int nfrags;
+	int assoclen;
+	int sglists;
+	int seqhilen;
+	__be32 *seqhi;
+	void *tmp;
+	u8 *iv;
+	struct scatterlist *sg;
+	struct scatterlist *asg;
+	int err = -EINVAL;
+
+	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
+		goto out;
+
+	if (elen <= 0)
+		goto out;
+
+	err = skb_cow_data(skb, 0, &trailer);
+	if (err < 0)
+		goto out;
+
+	nfrags = err;
+
+	assoclen = sizeof(*esph);
+	sglists = 1;
+	seqhilen = 0;
+
+	if (x->props.flags & XFRM_STATE_ESN) {
+		sglists += 2;
+		seqhilen += sizeof(__be32);
+		assoclen += seqhilen;
+	}
+
+	err = -ENOMEM;
+	tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
+	if (!tmp)
+		goto out;
+
+	ESP_SKB_CB(skb)->tmp = tmp;
+	seqhi = esp_tmp_seqhi(tmp);
+	iv = esp_tmp_iv(aead, tmp, seqhilen);
+	req = esp_tmp_req(aead, iv);
+	asg = esp_req_sg(aead, req);
+	sg = asg + sglists;
+
+	skb->ip_summed = CHECKSUM_NONE;
+
+	esph = (struct ip_esp_hdr *)skb->data;
+
+	/* Get ivec. This can be wrong, check against another impls. */
+	iv = esph->enc_data;
+
+	sg_init_table(sg, nfrags);
+	skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);
+
+	if ((x->props.flags & XFRM_STATE_ESN)) {
+		sg_init_table(asg, 3);
+		sg_set_buf(asg, &esph->spi, sizeof(__be32));
+		*seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
+		sg_set_buf(asg + 1, seqhi, seqhilen);
+		sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
+	} else
+		sg_init_one(asg, esph, sizeof(*esph));
+
+	aead_request_set_callback(req, 0, esp_input_done, skb);
+	aead_request_set_crypt(req, sg, sg, elen, iv);
+	aead_request_set_assoc(req, asg, assoclen);
+
+	err = crypto_aead_decrypt(req);
+	if (err == -EINPROGRESS)
+		goto out;
+
+	err = esp_input_done2(skb, err);
+
+out:
+	return err;
+}
+
+static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
+{
+	struct crypto_aead *aead = x->data;
+	u32 blksize = ALIGN(crypto_aead_blocksize(aead), 4);
+	unsigned int net_adj;
+
+	switch (x->props.mode) {
+	case XFRM_MODE_TRANSPORT:
+	case XFRM_MODE_BEET:
+		net_adj = sizeof(struct iphdr);
+		break;
+	case XFRM_MODE_TUNNEL:
+		net_adj = 0;
+		break;
+	default:
+		BUG();
+	}
+
+	return ((mtu - x->props.header_len - crypto_aead_authsize(aead) -
+		 net_adj) & ~(blksize - 1)) + net_adj - 2;
+}
+
+static int esp4_err(struct sk_buff *skb, u32 info)
+{
+	struct net *net = dev_net(skb->dev);
+	const struct iphdr *iph = (const struct iphdr *)skb->data;
+	struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
+	struct xfrm_state *x;
+
+	switch (icmp_hdr(skb)->type) {
+	case ICMP_DEST_UNREACH:
+		if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
+			return 0;
+	case ICMP_REDIRECT:
+		break;
+	default:
+		return 0;
+	}
+
+	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
+			      esph->spi, IPPROTO_ESP, AF_INET);
+	if (!x)
+		return 0;
+
+	if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
+		ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ESP, 0);
+	else
+		ipv4_redirect(skb, net, 0, 0, IPPROTO_ESP, 0);
+	xfrm_state_put(x);
+
+	return 0;
+}
+
+static void esp_destroy(struct xfrm_state *x)
+{
+	struct crypto_aead *aead = x->data;
+
+	if (!aead)
+		return;
+
+	crypto_free_aead(aead);
+}
+
+static int esp_init_aead(struct xfrm_state *x)
+{
+	struct crypto_aead *aead;
+	int err;
+
+	aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
+	err = PTR_ERR(aead);
+	if (IS_ERR(aead))
+		goto error;
+
+	x->data = aead;
+
+	err = crypto_aead_setkey(aead, x->aead->alg_key,
+				 (x->aead->alg_key_len + 7) / 8);
+	if (err)
+		goto error;
+
+	err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
+	if (err)
+		goto error;
+
+error:
+	return err;
+}
+
+static int esp_init_authenc(struct xfrm_state *x)
+{
+	struct crypto_aead *aead;
+	struct crypto_authenc_key_param *param;
+	struct rtattr *rta;
+	char *key;
+	char *p;
+	char authenc_name[CRYPTO_MAX_ALG_NAME];
+	unsigned int keylen;
+	int err;
+
+	err = -EINVAL;
+	if (!x->ealg)
+		goto error;
+
+	err = -ENAMETOOLONG;
+
+	if ((x->props.flags & XFRM_STATE_ESN)) {
+		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
+			     "authencesn(%s,%s)",
+			     x->aalg ? x->aalg->alg_name : "digest_null",
+			     x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
+			goto error;
+	} else {
+		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
+			     "authenc(%s,%s)",
+			     x->aalg ? x->aalg->alg_name : "digest_null",
+			     x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
+			goto error;
+	}
+
+	aead = crypto_alloc_aead(authenc_name, 0, 0);
+	err = PTR_ERR(aead);
+	if (IS_ERR(aead))
+		goto error;
+
+	x->data = aead;
+
+	keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
+		 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
+	err = -ENOMEM;
+	key = kmalloc(keylen, GFP_KERNEL);
+	if (!key)
+		goto error;
+
+	p = key;
+	rta = (void *)p;
+	rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
+	rta->rta_len = RTA_LENGTH(sizeof(*param));
+	param = RTA_DATA(rta);
+	p += RTA_SPACE(sizeof(*param));
+
+	if (x->aalg) {
+		struct xfrm_algo_desc *aalg_desc;
+
+		memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
+		p += (x->aalg->alg_key_len + 7) / 8;
+
+		aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
+		BUG_ON(!aalg_desc);
+
+		err = -EINVAL;
+		if (aalg_desc->uinfo.auth.icv_fullbits / 8 !=
+		    crypto_aead_authsize(aead)) {
+			pr_info("ESP: %s digestsize %u != %hu\n",
+				x->aalg->alg_name,
+				crypto_aead_authsize(aead),
+				aalg_desc->uinfo.auth.icv_fullbits / 8);
+			goto free_key;
+		}
+
+		err = crypto_aead_setauthsize(
+			aead, x->aalg->alg_trunc_len / 8);
+		if (err)
+			goto free_key;
+	}
+
+	param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
+	memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
+
+	err = crypto_aead_setkey(aead, key, keylen);
+
+free_key:
+	kfree(key);
+
+error:
+	return err;
+}
+
+static int esp_init_state(struct xfrm_state *x)
+{
+	struct crypto_aead *aead;
+	u32 align;
+	int err;
+
+	x->data = NULL;
+
+	if (x->aead)
+		err = esp_init_aead(x);
+	else
+		err = esp_init_authenc(x);
+
+	if (err)
+		goto error;
+
+	aead = x->data;
+
+	x->props.header_len = sizeof(struct ip_esp_hdr) +
+			      crypto_aead_ivsize(aead);
+	if (x->props.mode == XFRM_MODE_TUNNEL)
+		x->props.header_len += sizeof(struct iphdr);
+	else if (x->props.mode == XFRM_MODE_BEET && x->sel.family != AF_INET6)
+		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;
+		}
+	}
+
+	align = ALIGN(crypto_aead_blocksize(aead), 4);
+	x->props.trailer_len = align + 1 + crypto_aead_authsize(aead);
+
+error:
+	return err;
+}
+
+static int esp4_rcv_cb(struct sk_buff *skb, int err)
+{
+	return 0;
+}
+
+static const 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 xfrm4_protocol esp4_protocol = {
+	.handler	=	xfrm4_rcv,
+	.input_handler	=	xfrm_input,
+	.cb_handler	=	esp4_rcv_cb,
+	.err_handler	=	esp4_err,
+	.priority	=	0,
+};
+
+static int __init esp4_init(void)
+{
+	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
+		pr_info("%s: can't add xfrm type\n", __func__);
+		return -EAGAIN;
+	}
+	if (xfrm4_protocol_register(&esp4_protocol, IPPROTO_ESP) < 0) {
+		pr_info("%s: can't add protocol\n", __func__);
+		xfrm_unregister_type(&esp_type, AF_INET);
+		return -EAGAIN;
+	}
+	return 0;
+}
+
+static void __exit esp4_fini(void)
+{
+	if (xfrm4_protocol_deregister(&esp4_protocol, IPPROTO_ESP) < 0)
+		pr_info("%s: can't remove protocol\n", __func__);
+	if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
+		pr_info("%s: can't remove xfrm type\n", __func__);
+}
+
+module_init(esp4_init);
+module_exit(esp4_fini);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);