crypto: crc32c - Add ahash implementation

This patch reimplements crc32c using the ahash interface.  This
allows one tfm to be used by an unlimited number of users provided
that they all use the same key (which all current crc32c users do).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/Kconfig

@@ -213,7 +213,7 @@ comment "Digest"
 
 config CRYPTO_CRC32C
 	tristate "CRC32c CRC algorithm"
-	select CRYPTO_ALGAPI
+	select CRYPTO_HASH
 	select LIBCRC32C
 	help
 	  Castagnoli, et al Cyclic Redundancy-Check Algorithm.  Used

crypto/crc32c.c

@@ -5,20 +5,23 @@
  *
  * This module file is a wrapper to invoke the lib/crc32c routines.
  *
+ * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
+ *
  * 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/internal/hash.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/string.h>
-#include <linux/crypto.h>
 #include <linux/crc32c.h>
 #include <linux/kernel.h>
 
-#define CHKSUM_BLOCK_SIZE	32
+#define CHKSUM_BLOCK_SIZE	1
 #define CHKSUM_DIGEST_SIZE	4
 
 struct chksum_ctx {
@@ -71,7 +74,7 @@ static void chksum_final(struct crypto_tfm *tfm, u8 *out)
 	*(__le32 *)out = ~cpu_to_le32(mctx->crc);
 }
 
-static int crc32c_cra_init(struct crypto_tfm *tfm)
+static int crc32c_cra_init_old(struct crypto_tfm *tfm)
 {
 	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
 
@@ -79,14 +82,14 @@ static int crc32c_cra_init(struct crypto_tfm *tfm)
 	return 0;
 }
 
-static struct crypto_alg alg = {
+static struct crypto_alg old_alg = {
 	.cra_name	=	"crc32c",
 	.cra_flags	=	CRYPTO_ALG_TYPE_DIGEST,
 	.cra_blocksize	=	CHKSUM_BLOCK_SIZE,
 	.cra_ctxsize	=	sizeof(struct chksum_ctx),
 	.cra_module	=	THIS_MODULE,
-	.cra_list	=	LIST_HEAD_INIT(alg.cra_list),
-	.cra_init	=	crc32c_cra_init,
+	.cra_list	=	LIST_HEAD_INIT(old_alg.cra_list),
+	.cra_init	=	crc32c_cra_init_old,
 	.cra_u		=	{
 		.digest = {
 			 .dia_digestsize=	CHKSUM_DIGEST_SIZE,
@@ -98,14 +101,125 @@ static struct crypto_alg alg = {
 	}
 };
 
+/*
+ * Setting the seed allows arbitrary accumulators and flexible XOR policy
+ * If your algorithm starts with ~0, then XOR with ~0 before you set
+ * the seed.
+ */
+static int crc32c_setkey(struct crypto_ahash *hash, const u8 *key,
+			 unsigned int keylen)
+{
+	u32 *mctx = crypto_ahash_ctx(hash);
+
+	if (keylen != sizeof(u32)) {
+		crypto_ahash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
+		return -EINVAL;
+	}
+	*mctx = le32_to_cpup((__le32 *)key);
+	return 0;
+}
+
+static int crc32c_init(struct ahash_request *req)
+{
+	u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
+	u32 *crcp = ahash_request_ctx(req);
+
+	*crcp = *mctx;
+	return 0;
+}
+
+static int crc32c_update(struct ahash_request *req)
+{
+	struct crypto_hash_walk walk;
+	u32 *crcp = ahash_request_ctx(req);
+	u32 crc = *crcp;
+	int nbytes;
+
+	for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
+	     nbytes = crypto_hash_walk_done(&walk, 0))
+		crc = crc32c(crc, walk.data, nbytes);
+
+	*crcp = crc;
+	return 0;
+}
+
+static int crc32c_final(struct ahash_request *req)
+{
+	u32 *crcp = ahash_request_ctx(req);
+	
+	*(__le32 *)req->result = ~cpu_to_le32p(crcp);
+	return 0;
+}
+
+static int crc32c_digest(struct ahash_request *req)
+{
+	struct crypto_hash_walk walk;
+	u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
+	u32 crc = *mctx;
+	int nbytes;
+
+	for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
+	     nbytes = crypto_hash_walk_done(&walk, 0))
+		crc = crc32c(crc, walk.data, nbytes);
+
+	*(__le32 *)req->result = ~cpu_to_le32(crc);
+	return 0;
+}
+
+static int crc32c_cra_init(struct crypto_tfm *tfm)
+{
+	u32 *key = crypto_tfm_ctx(tfm);
+
+	*key = ~0;
+
+	tfm->crt_ahash.reqsize = sizeof(u32);
+
+	return 0;
+}
+
+static struct crypto_alg alg = {
+	.cra_name		=	"crc32c",
+	.cra_driver_name	=	"crc32c-generic",
+	.cra_priority		=	100,
+	.cra_flags		=	CRYPTO_ALG_TYPE_AHASH,
+	.cra_blocksize		=	CHKSUM_BLOCK_SIZE,
+	.cra_alignmask		=	3,
+	.cra_ctxsize		=	sizeof(u32),
+	.cra_module		=	THIS_MODULE,
+	.cra_list		=	LIST_HEAD_INIT(alg.cra_list),
+	.cra_init		=	crc32c_cra_init,
+	.cra_type		=	&crypto_ahash_type,
+	.cra_u			=	{
+		.ahash = {
+			 .digestsize	=	CHKSUM_DIGEST_SIZE,
+			 .setkey	=	crc32c_setkey,
+			 .init   	= 	crc32c_init,
+			 .update 	=	crc32c_update,
+			 .final  	=	crc32c_final,
+			 .digest  	=	crc32c_digest,
+		 }
+	}
+};
+
 static int __init crc32c_mod_init(void)
 {
-	return crypto_register_alg(&alg);
+	int err;
+
+	err = crypto_register_alg(&old_alg);
+	if (err)
+		return err;
+
+	err = crypto_register_alg(&alg);
+	if (err)
+		crypto_unregister_alg(&old_alg);
+
+	return err;
 }
 
 static void __exit crc32c_mod_fini(void)
 {
 	crypto_unregister_alg(&alg);
+	crypto_unregister_alg(&old_alg);
 }
 
 module_init(crc32c_mod_init);