Re: [PATCH 0/8] crypto: Add lskcipher API type

[Herbert Xu <herbert@gondor.apana.org.au>]

On Thu, Sep 14, 2023 at 10:51:21AM +0200, Ard Biesheuvel wrote:
>
> So the intent is for lskcipher to ultimately supplant the current
> cipher entirely, right? And lskcipher can be used directly by clients
> of the crypto API, in which case kernel VAs may be used directly, but
> no async support is available, while skcipher API clients will gain
> access to lskciphers via a generic wrapper (if needed?)
> 
> That makes sense but it would help to spell this out.

Yes that's the idea.  It is pretty much exactly the same as how
shash and ahash are handled and used.

Because of the way I structured the ecb transition code (it will
take an old cipher and repackage it as an lskcipher), we need to
convert the templates first and then do the cipher => lskcipher
conversion.

> I'd be happy to help out here but I'll be off on vacation for ~3 weeks
> after this week so i won't get around to it before mid October. What I
> will do (if it helps) is rebase my recent RISC-V scalar AES cipher
> patches onto this, and implement ecb(aes) instead (which is the idea
> IIUC?)

That sounds good.  In fact let me attach the aes-generic proof-
of-concept conversion (it can only be applied after all templates
have been converted, so if you test it now everything but ecb/cbc
will be broken).

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
diff --git a/crypto/aes_generic.c b/crypto/aes_generic.c
index 666474b81c6a..afb74ee04193 100644
--- a/crypto/aes_generic.c
+++ b/crypto/aes_generic.c
@@ -47,14 +47,13 @@
  * ---------------------------------------------------------------------------
  */
 
-#include <crypto/aes.h>
-#include <crypto/algapi.h>
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/types.h>
-#include <linux/errno.h>
-#include <asm/byteorder.h>
 #include <asm/unaligned.h>
+#include <crypto/aes.h>
+#include <crypto/internal/skcipher.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
 
 static inline u8 byte(const u32 x, const unsigned n)
 {
@@ -1123,7 +1122,7 @@ EXPORT_SYMBOL_GPL(crypto_it_tab);
 
 /**
  * crypto_aes_set_key - Set the AES key.
- * @tfm:	The %crypto_tfm that is used in the context.
+ * @tfm:	The %crypto_lskcipher that is used in the context.
  * @in_key:	The input key.
  * @key_len:	The size of the key.
  *
@@ -1133,10 +1132,10 @@ EXPORT_SYMBOL_GPL(crypto_it_tab);
  *
  * Return: 0 on success; -EINVAL on failure (only happens for bad key lengths)
  */
-int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
-		unsigned int key_len)
+int crypto_aes_set_key(struct crypto_lskcipher *tfm, const u8 *in_key,
+		       unsigned int key_len)
 {
-	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct crypto_aes_ctx *ctx = crypto_lskcipher_ctx(tfm);
 
 	return aes_expandkey(ctx, in_key, key_len);
 }
@@ -1173,9 +1172,9 @@ EXPORT_SYMBOL_GPL(crypto_aes_set_key);
 	f_rl(bo, bi, 3, k);	\
 } while (0)
 
-static void crypto_aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+static void aes_encrypt_one(struct crypto_lskcipher *tfm, const u8 *in, u8 *out)
 {
-	const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
+	const struct crypto_aes_ctx *ctx = crypto_lskcipher_ctx(tfm);
 	u32 b0[4], b1[4];
 	const u32 *kp = ctx->key_enc + 4;
 	const int key_len = ctx->key_length;
@@ -1212,6 +1211,17 @@ static void crypto_aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 	put_unaligned_le32(b0[3], out + 12);
 }
 
+static int crypto_aes_encrypt(struct crypto_lskcipher *tfm, const u8 *src,
+			      u8 *dst, unsigned nbytes, u8 *iv, bool final)
+{
+	const unsigned int bsize = AES_BLOCK_SIZE;
+
+	for (; nbytes >= bsize; src += bsize, dst += bsize, nbytes -= bsize)
+		aes_encrypt_one(tfm, src, dst);
+
+	return nbytes && final ? -EINVAL : nbytes;
+}
+
 /* decrypt a block of text */
 
 #define i_rn(bo, bi, n, k)	do {				\
@@ -1243,9 +1253,9 @@ static void crypto_aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 	i_rl(bo, bi, 3, k);	\
 } while (0)
 
-static void crypto_aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+static void aes_decrypt_one(struct crypto_lskcipher *tfm, const u8 *in, u8 *out)
 {
-	const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
+	const struct crypto_aes_ctx *ctx = crypto_lskcipher_ctx(tfm);
 	u32 b0[4], b1[4];
 	const int key_len = ctx->key_length;
 	const u32 *kp = ctx->key_dec + 4;
@@ -1282,33 +1292,41 @@ static void crypto_aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 	put_unaligned_le32(b0[3], out + 12);
 }
 
-static struct crypto_alg aes_alg = {
-	.cra_name		=	"aes",
-	.cra_driver_name	=	"aes-generic",
-	.cra_priority		=	100,
-	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
-	.cra_blocksize		=	AES_BLOCK_SIZE,
-	.cra_ctxsize		=	sizeof(struct crypto_aes_ctx),
-	.cra_module		=	THIS_MODULE,
-	.cra_u			=	{
-		.cipher = {
-			.cia_min_keysize	=	AES_MIN_KEY_SIZE,
-			.cia_max_keysize	=	AES_MAX_KEY_SIZE,
-			.cia_setkey		=	crypto_aes_set_key,
-			.cia_encrypt		=	crypto_aes_encrypt,
-			.cia_decrypt		=	crypto_aes_decrypt
-		}
-	}
+static int crypto_aes_decrypt(struct crypto_lskcipher *tfm, const u8 *src,
+			      u8 *dst, unsigned nbytes, u8 *iv, bool final)
+{
+	const unsigned int bsize = AES_BLOCK_SIZE;
+
+	for (; nbytes >= bsize; src += bsize, dst += bsize, nbytes -= bsize)
+		aes_decrypt_one(tfm, src, dst);
+
+	return nbytes && final ? -EINVAL : nbytes;
+}
+
+static struct lskcipher_alg aes_alg = {
+	.co = {
+		.base.cra_name		=	"aes",
+		.base.cra_driver_name	=	"aes-generic",
+		.base.cra_priority	=	100,
+		.base.cra_blocksize	=	AES_BLOCK_SIZE,
+		.base.cra_ctxsize	=	sizeof(struct crypto_aes_ctx),
+		.base.cra_module	=	THIS_MODULE,
+		.min_keysize		=	AES_MIN_KEY_SIZE,
+		.max_keysize		=	AES_MAX_KEY_SIZE,
+	},
+	.setkey				=	crypto_aes_set_key,
+	.encrypt			=	crypto_aes_encrypt,
+	.decrypt			=	crypto_aes_decrypt,
 };
 
 static int __init aes_init(void)
 {
-	return crypto_register_alg(&aes_alg);
+	return crypto_register_lskcipher(&aes_alg);
 }
 
 static void __exit aes_fini(void)
 {
-	crypto_unregister_alg(&aes_alg);
+	crypto_unregister_lskcipher(&aes_alg);
 }
 
 subsys_initcall(aes_init);
diff --git a/include/crypto/aes.h b/include/crypto/aes.h
index 2090729701ab..947109e24360 100644
--- a/include/crypto/aes.h
+++ b/include/crypto/aes.h
@@ -6,8 +6,9 @@
 #ifndef _CRYPTO_AES_H
 #define _CRYPTO_AES_H
 
+#include <linux/cache.h>
+#include <linux/errno.h>
 #include <linux/types.h>
-#include <linux/crypto.h>
 
 #define AES_MIN_KEY_SIZE	16
 #define AES_MAX_KEY_SIZE	32
@@ -18,6 +19,8 @@
 #define AES_MAX_KEYLENGTH	(15 * 16)
 #define AES_MAX_KEYLENGTH_U32	(AES_MAX_KEYLENGTH / sizeof(u32))
 
+struct crypto_lskcipher;
+
 /*
  * Please ensure that the first two fields are 16-byte aligned
  * relative to the start of the structure, i.e., don't move them!
@@ -48,8 +51,8 @@ static inline int aes_check_keylen(unsigned int keylen)
 	return 0;
 }
 
-int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
-		unsigned int key_len);
+int crypto_aes_set_key(struct crypto_lskcipher *tfm, const u8 *in_key,
+		       unsigned int key_len);
 
 /**
  * aes_expandkey - Expands the AES key as described in FIPS-197