[CRYPTO] api: Add aead crypto type

This patch adds crypto_aead which is the interface for AEAD
(Authenticated Encryption with Associated Data) algorithms.

AEAD algorithms perform authentication and encryption in one
step.  Traditionally users (such as IPsec) would use two
different crypto algorithms to perform these.  With AEAD
this comes down to one algorithm and one operation.

Of course if traditional algorithms were used we'd still
be doing two operations underneath.  However, real AEAD
algorithms may allow the underlying operations to be
optimised as well.

Signed-off-by: Herbert Xu <[email protected]>

crypto/Kconfig

@@ -28,6 +28,10 @@ config CRYPTO_ABLKCIPHER
 	tristate
 	select CRYPTO_BLKCIPHER
 
+config CRYPTO_AEAD
+	tristate
+	select CRYPTO_ALGAPI
+
 config CRYPTO_BLKCIPHER
 	tristate
 	select CRYPTO_ALGAPI

crypto/Makefile

@@ -9,6 +9,7 @@ crypto_algapi-objs := algapi.o $(crypto_algapi-y)
 obj-$(CONFIG_CRYPTO_ALGAPI) += crypto_algapi.o
 
 obj-$(CONFIG_CRYPTO_ABLKCIPHER) += ablkcipher.o
+obj-$(CONFIG_CRYPTO_AEAD) += aead.o
 obj-$(CONFIG_CRYPTO_BLKCIPHER) += blkcipher.o
 
 crypto_hash-objs := hash.o

crypto/aead.c

@@ -0,0 +1,101 @@
+/*
+ * AEAD: Authenticated Encryption with Associated Data
+ * 
+ * This file provides API support for AEAD algorithms.
+ *
+ * Copyright (c) 2007 Herbert Xu <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option) 
+ * any later version.
+ *
+ */
+
+#include <crypto/algapi.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+
+static int setkey_unaligned(struct crypto_aead *tfm, const u8 *key,
+			    unsigned int keylen)
+{
+	struct aead_alg *aead = crypto_aead_alg(tfm);
+	unsigned long alignmask = crypto_aead_alignmask(tfm);
+	int ret;
+	u8 *buffer, *alignbuffer;
+	unsigned long absize;
+
+	absize = keylen + alignmask;
+	buffer = kmalloc(absize, GFP_ATOMIC);
+	if (!buffer)
+		return -ENOMEM;
+
+	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
+	memcpy(alignbuffer, key, keylen);
+	ret = aead->setkey(tfm, alignbuffer, keylen);
+	memset(alignbuffer, 0, keylen);
+	kfree(buffer);
+	return ret;
+}
+
+static int setkey(struct crypto_aead *tfm, const u8 *key, unsigned int keylen)
+{
+	struct aead_alg *aead = crypto_aead_alg(tfm);
+	unsigned long alignmask = crypto_aead_alignmask(tfm);
+
+	if ((unsigned long)key & alignmask)
+		return setkey_unaligned(tfm, key, keylen);
+
+	return aead->setkey(tfm, key, keylen);
+}
+
+static unsigned int crypto_aead_ctxsize(struct crypto_alg *alg, u32 type,
+					u32 mask)
+{
+	return alg->cra_ctxsize;
+}
+
+static int crypto_init_aead_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
+{
+	struct aead_alg *alg = &tfm->__crt_alg->cra_aead;
+	struct aead_tfm *crt = &tfm->crt_aead;
+
+	if (max(alg->authsize, alg->ivsize) > PAGE_SIZE / 8)
+		return -EINVAL;
+
+	crt->setkey = setkey;
+	crt->encrypt = alg->encrypt;
+	crt->decrypt = alg->decrypt;
+	crt->ivsize = alg->ivsize;
+	crt->authsize = alg->authsize;
+
+	return 0;
+}
+
+static void crypto_aead_show(struct seq_file *m, struct crypto_alg *alg)
+	__attribute__ ((unused));
+static void crypto_aead_show(struct seq_file *m, struct crypto_alg *alg)
+{
+	struct aead_alg *aead = &alg->cra_aead;
+
+	seq_printf(m, "type         : aead\n");
+	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
+	seq_printf(m, "ivsize       : %u\n", aead->ivsize);
+	seq_printf(m, "authsize     : %u\n", aead->authsize);
+}
+
+const struct crypto_type crypto_aead_type = {
+	.ctxsize = crypto_aead_ctxsize,
+	.init = crypto_init_aead_ops,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_aead_show,
+#endif
+};
+EXPORT_SYMBOL_GPL(crypto_aead_type);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Authenticated Encryption with Associated Data (AEAD)");

include/crypto/algapi.h

@@ -94,6 +94,7 @@ struct blkcipher_walk {
 };
 
 extern const struct crypto_type crypto_ablkcipher_type;
+extern const struct crypto_type crypto_aead_type;
 extern const struct crypto_type crypto_blkcipher_type;
 extern const struct crypto_type crypto_hash_type;
 
@@ -165,6 +166,11 @@ static inline void *crypto_ablkcipher_ctx_aligned(struct crypto_ablkcipher *tfm)
 	return crypto_tfm_ctx_aligned(&tfm->base);
 }
 
+static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
+{
+	return &crypto_aead_tfm(tfm)->__crt_alg->cra_aead;
+}
+
 static inline struct crypto_blkcipher *crypto_spawn_blkcipher(
 	struct crypto_spawn *spawn)
 {