crypto: crct10dif - Add fallback for broken initrds

Unfortunately, even with a softdep some distros fail to include
the necessary modules in the initrd.  Therefore this patch adds
a fallback path to restore existing behaviour where we cannot
load the new crypto crct10dif algorithm.

In order to do this, the underlying crct10dif has been split out
from the crypto implementation so that it can be used on the
fallback path.

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

4 files changed, 140 insertions, 100 deletions

diff --git a/crypto/Makefile b/crypto/Makefile
index 2d5ed08a239f..80019ba8da3a 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -83,7 +83,7 @@ obj-$(CONFIG_CRYPTO_ZLIB) += zlib.o
 obj-$(CONFIG_CRYPTO_MICHAEL_MIC) += michael_mic.o
 obj-$(CONFIG_CRYPTO_CRC32C) += crc32c.o
 obj-$(CONFIG_CRYPTO_CRC32) += crc32.o
-obj-$(CONFIG_CRYPTO_CRCT10DIF) += crct10dif.o
+obj-$(CONFIG_CRYPTO_CRCT10DIF) += crct10dif_common.o crct10dif_generic.o
 obj-$(CONFIG_CRYPTO_AUTHENC) += authenc.o authencesn.o
 obj-$(CONFIG_CRYPTO_LZO) += lzo.o
 obj-$(CONFIG_CRYPTO_LZ4) += lz4.o
diff --git a/crypto/crct10dif.c b/crypto/crct10dif_common.c
index 92aca96d6b98..b2fab366f518 100644
--- a/crypto/crct10dif.c
+++ b/crypto/crct10dif_common.c
@@ -24,18 +24,10 @@
  *
  */
 
-#include <linux/types.h>
-#include <linux/module.h>
 #include <linux/crc-t10dif.h>
-#include <crypto/internal/hash.h>
-#include <linux/init.h>
-#include <linux/string.h>
+#include <linux/module.h>
 #include <linux/kernel.h>
 
-struct chksum_desc_ctx {
-	__u16 crc;
-};
-
 /* Table generated using the following polynomium:
  * x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
  * gt: 0x8bb7
@@ -86,93 +78,5 @@ __u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer, size_t len)
 }
 EXPORT_SYMBOL(crc_t10dif_generic);
 
-/*
- * Steps through buffer one byte at at time, calculates reflected
- * crc using table.
- */
-
-static int chksum_init(struct shash_desc *desc)
-{
-	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
-
-	ctx->crc = 0;
-
-	return 0;
-}
-
-static int chksum_update(struct shash_desc *desc, const u8 *data,
-			 unsigned int length)
-{
-	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
-
-	ctx->crc = crc_t10dif_generic(ctx->crc, data, length);
-	return 0;
-}
-
-static int chksum_final(struct shash_desc *desc, u8 *out)
-{
-	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
-
-	*(__u16 *)out = ctx->crc;
-	return 0;
-}
-
-static int __chksum_finup(__u16 *crcp, const u8 *data, unsigned int len,
-			u8 *out)
-{
-	*(__u16 *)out = crc_t10dif_generic(*crcp, data, len);
-	return 0;
-}
-
-static int chksum_finup(struct shash_desc *desc, const u8 *data,
-			unsigned int len, u8 *out)
-{
-	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
-
-	return __chksum_finup(&ctx->crc, data, len, out);
-}
-
-static int chksum_digest(struct shash_desc *desc, const u8 *data,
-			 unsigned int length, u8 *out)
-{
-	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
-
-	return __chksum_finup(&ctx->crc, data, length, out);
-}
-
-static struct shash_alg alg = {
-	.digestsize		=	CRC_T10DIF_DIGEST_SIZE,
-	.init		=	chksum_init,
-	.update		=	chksum_update,
-	.final		=	chksum_final,
-	.finup		=	chksum_finup,
-	.digest		=	chksum_digest,
-	.descsize		=	sizeof(struct chksum_desc_ctx),
-	.base			=	{
-		.cra_name		=	"crct10dif",
-		.cra_driver_name	=	"crct10dif-generic",
-		.cra_priority		=	100,
-		.cra_blocksize		=	CRC_T10DIF_BLOCK_SIZE,
-		.cra_module		=	THIS_MODULE,
-	}
-};
-
-static int __init crct10dif_mod_init(void)
-{
-	int ret;
-
-	ret = crypto_register_shash(&alg);
-	return ret;
-}
-
-static void __exit crct10dif_mod_fini(void)
-{
-	crypto_unregister_shash(&alg);
-}
-
-module_init(crct10dif_mod_init);
-module_exit(crct10dif_mod_fini);
-
-MODULE_AUTHOR("Tim Chen <tim.c.chen@linux.intel.com>");
-MODULE_DESCRIPTION("T10 DIF CRC calculation.");
+MODULE_DESCRIPTION("T10 DIF CRC calculation common code");
 MODULE_LICENSE("GPL");
diff --git a/crypto/crct10dif_generic.c b/crypto/crct10dif_generic.c
new file mode 100644
index 000000000000..877e7114ec5c
--- /dev/null
+++ b/crypto/crct10dif_generic.c
@@ -0,0 +1,127 @@
+/*
+ * Cryptographic API.
+ *
+ * T10 Data Integrity Field CRC16 Crypto Transform
+ *
+ * Copyright (c) 2007 Oracle Corporation.  All rights reserved.
+ * Written by Martin K. Petersen <martin.petersen@oracle.com>
+ * Copyright (C) 2013 Intel Corporation
+ * Author: Tim Chen <tim.c.chen@linux.intel.com>
+ *
+ * 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.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/crc-t10dif.h>
+#include <crypto/internal/hash.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+
+struct chksum_desc_ctx {
+	__u16 crc;
+};
+
+/*
+ * Steps through buffer one byte at at time, calculates reflected
+ * crc using table.
+ */
+
+static int chksum_init(struct shash_desc *desc)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	ctx->crc = 0;
+
+	return 0;
+}
+
+static int chksum_update(struct shash_desc *desc, const u8 *data,
+			 unsigned int length)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	ctx->crc = crc_t10dif_generic(ctx->crc, data, length);
+	return 0;
+}
+
+static int chksum_final(struct shash_desc *desc, u8 *out)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	*(__u16 *)out = ctx->crc;
+	return 0;
+}
+
+static int __chksum_finup(__u16 *crcp, const u8 *data, unsigned int len,
+			u8 *out)
+{
+	*(__u16 *)out = crc_t10dif_generic(*crcp, data, len);
+	return 0;
+}
+
+static int chksum_finup(struct shash_desc *desc, const u8 *data,
+			unsigned int len, u8 *out)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	return __chksum_finup(&ctx->crc, data, len, out);
+}
+
+static int chksum_digest(struct shash_desc *desc, const u8 *data,
+			 unsigned int length, u8 *out)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	return __chksum_finup(&ctx->crc, data, length, out);
+}
+
+static struct shash_alg alg = {
+	.digestsize		=	CRC_T10DIF_DIGEST_SIZE,
+	.init		=	chksum_init,
+	.update		=	chksum_update,
+	.final		=	chksum_final,
+	.finup		=	chksum_finup,
+	.digest		=	chksum_digest,
+	.descsize		=	sizeof(struct chksum_desc_ctx),
+	.base			=	{
+		.cra_name		=	"crct10dif",
+		.cra_driver_name	=	"crct10dif-generic",
+		.cra_priority		=	100,
+		.cra_blocksize		=	CRC_T10DIF_BLOCK_SIZE,
+		.cra_module		=	THIS_MODULE,
+	}
+};
+
+static int __init crct10dif_mod_init(void)
+{
+	int ret;
+
+	ret = crypto_register_shash(&alg);
+	return ret;
+}
+
+static void __exit crct10dif_mod_fini(void)
+{
+	crypto_unregister_shash(&alg);
+}
+
+module_init(crct10dif_mod_init);
+module_exit(crct10dif_mod_fini);
+
+MODULE_AUTHOR("Tim Chen <tim.c.chen@linux.intel.com>");
+MODULE_DESCRIPTION("T10 DIF CRC calculation.");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("crct10dif");
diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
index 43bc5b071f96..dfe6ec17c0a5 100644
--- a/lib/crc-t10dif.c
+++ b/lib/crc-t10dif.c
@@ -14,8 +14,10 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <crypto/hash.h>
+#include <linux/static_key.h>
 
 static struct crypto_shash *crct10dif_tfm;
+static struct static_key crct10dif_fallback __read_mostly;
 
 __u16 crc_t10dif(const unsigned char *buffer, size_t len)
 {
@@ -25,6 +27,9 @@ __u16 crc_t10dif(const unsigned char *buffer, size_t len)
 	} desc;
 	int err;
 
+	if (static_key_false(&crct10dif_fallback))
+		return crc_t10dif_generic(0, buffer, len);
+
 	desc.shash.tfm = crct10dif_tfm;
 	desc.shash.flags = 0;
 	*(__u16 *)desc.ctx = 0;
@@ -39,7 +44,11 @@ EXPORT_SYMBOL(crc_t10dif);
 static int __init crc_t10dif_mod_init(void)
 {
 	crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
-	return PTR_RET(crct10dif_tfm);
+	if (IS_ERR(crct10dif_tfm)) {
+		static_key_slow_inc(&crct10dif_fallback);
+		crct10dif_tfm = NULL;
+	}
+	return 0;
 }
 
 static void __exit crc_t10dif_mod_fini(void)