[IPSEC]: Use crypto_aead and authenc in ESP

This patch converts ESP to use the crypto_aead interface and in particular
the authenc algorithm.  This lays the foundations for future support of
combined mode algorithms.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/esp.h

 #ifndef _NET_ESP_H
 #define _NET_ESP_H
 
-#include <linux/crypto.h>
-#include <net/xfrm.h>
-#include <linux/scatterlist.h>
+#include <linux/skbuff.h>
 
-#define ESP_NUM_FAST_SG		4
+struct crypto_aead;
 
-struct esp_data
-{
-	struct scatterlist		sgbuf[ESP_NUM_FAST_SG];
-
-	/* Confidentiality */
-	struct {
-		int			padlen;		/* 0..255 */
-		/* ivlen is offset from enc_data, where encrypted data start.
-		 * It is logically different of crypto_tfm_alg_ivsize(tfm).
-		 * We assume that it is either zero (no ivec), or
-		 * >= crypto_tfm_alg_ivsize(tfm). */
-		int			ivlen;
-		int			ivinitted;
-		u8			*ivec;		/* ivec buffer */
-		struct crypto_blkcipher	*tfm;		/* crypto handle */
-	} conf;
-
-	/* Integrity. It is active when icv_full_len != 0 */
-	struct {
-		u8			*work_icv;
-		int			icv_full_len;
-		int			icv_trunc_len;
-		struct crypto_hash	*tfm;
-	} auth;
+struct esp_data {
+	/* 0..255 */
+	int padlen;
+
+	/* Confidentiality & Integrity */
+	struct crypto_aead *aead;
 };
 
 extern void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
 
-static inline int esp_mac_digest(struct esp_data *esp, struct sk_buff *skb,
-				 int offset, int len)
-{
-	struct hash_desc desc;
-	int err;
-
-	desc.tfm = esp->auth.tfm;
-	desc.flags = 0;
-
-	err = crypto_hash_init(&desc);
-	if (unlikely(err))
-		return err;
-	err = skb_icv_walk(skb, &desc, offset, len, crypto_hash_update);
-	if (unlikely(err))
-		return err;
-	return crypto_hash_final(&desc, esp->auth.work_icv);
-}
-
 struct ip_esp_hdr;
 
 static inline struct ip_esp_hdr *ip_esp_hdr(const struct sk_buff *skb)

net/ipv4/Kconfig

@@ -343,6 +343,7 @@ config INET_ESP
 	tristate "IP: ESP transformation"
 	select XFRM
 	select CRYPTO
+	select CRYPTO_AEAD
 	select CRYPTO_HMAC
 	select CRYPTO_MD5
 	select CRYPTO_CBC

net/ipv6/Kconfig

@@ -85,6 +85,7 @@ config INET6_ESP
 	depends on IPV6
 	select XFRM
 	select CRYPTO
+	select CRYPTO_AEAD
 	select CRYPTO_HMAC
 	select CRYPTO_MD5
 	select CRYPTO_CBC