[PATCH 1/2] crypto/crc32: Provide crc32-base alias to enable fuzz testing

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

crc32-generic is backed by the architecture's CRC-32 library, which may
offer a variety of implementations depending on the capabilities of the
platform. These are not covered by the crypto subsystem's fuzz testing
capabilities because crc32-generic is the reference driver that the
fuzzing logic uses as a source of truth.

Fix this by proving a crc32-base implementation which is always based on
the generic C implementation, and wire it up as the reference
implementation for the fuzz tester.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 crypto/crc32_generic.c | 73 ++++++++++++++------
 crypto/testmgr.c       |  1 +
 2 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/crypto/crc32_generic.c b/crypto/crc32_generic.c
index d1251663ed66..73948ce96ac7 100644
--- a/crypto/crc32_generic.c
+++ b/crypto/crc32_generic.c
@@ -63,6 +63,17 @@ static int crc32_update(struct shash_desc *desc, const u8 *data,
 	return 0;
 }
 
+#ifdef CONFIG_CRYPTO_MANAGER_EXTRA_TESTS
+static int crc32_update_base(struct shash_desc *desc, const u8 *data,
+			     unsigned int len)
+{
+	u32 *crcp = shash_desc_ctx(desc);
+
+	*crcp = crc32_le_base(*crcp, data, len);
+	return 0;
+}
+#endif
+
 /* No final XOR 0xFFFFFFFF, like crc32_le */
 static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len,
 			 u8 *out)
@@ -91,35 +102,53 @@ static int crc32_digest(struct shash_desc *desc, const u8 *data,
 	return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len,
 			     out);
 }
-static struct shash_alg alg = {
-	.setkey		= crc32_setkey,
-	.init		= crc32_init,
-	.update		= crc32_update,
-	.final		= crc32_final,
-	.finup		= crc32_finup,
-	.digest		= crc32_digest,
-	.descsize	= sizeof(u32),
-	.digestsize	= CHKSUM_DIGEST_SIZE,
-	.base		= {
-		.cra_name		= "crc32",
-		.cra_driver_name	= "crc32-generic",
-		.cra_priority		= 100,
-		.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
-		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
-		.cra_ctxsize		= sizeof(u32),
-		.cra_module		= THIS_MODULE,
-		.cra_init		= crc32_cra_init,
-	}
-};
+static struct shash_alg algs[] = {{
+	.setkey			= crc32_setkey,
+	.init			= crc32_init,
+	.update			= crc32_update,
+	.final			= crc32_final,
+	.finup			= crc32_finup,
+	.digest			= crc32_digest,
+	.descsize		= sizeof(u32),
+	.digestsize		= CHKSUM_DIGEST_SIZE,
+
+	.base.cra_name		= "crc32",
+	.base.cra_driver_name	= "crc32-generic",
+	.base.cra_priority	= 100,
+	.base.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
+	.base.cra_blocksize	= CHKSUM_BLOCK_SIZE,
+	.base.cra_ctxsize	= sizeof(u32),
+	.base.cra_module	= THIS_MODULE,
+	.base.cra_init		= crc32_cra_init,
+#ifdef CONFIG_CRYPTO_MANAGER_EXTRA_TESTS
+}, {
+	.setkey			= crc32_setkey,
+	.init			= crc32_init,
+	.update			= crc32_update_base,
+	.final			= crc32_final,
+	.digest			= crc32_digest,
+	.descsize		= sizeof(u32),
+	.digestsize		= CHKSUM_DIGEST_SIZE,
+
+	.base.cra_name		= "crc32",
+	.base.cra_driver_name	= "crc32-base",
+	.base.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
+	.base.cra_blocksize	= CHKSUM_BLOCK_SIZE,
+	.base.cra_ctxsize	= sizeof(u32),
+	.base.cra_module	= THIS_MODULE,
+	.base.cra_init		= crc32_cra_init,
+#endif
+}};
 
 static int __init crc32_mod_init(void)
 {
-	return crypto_register_shash(&alg);
+	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
 }
 
 static void __exit crc32_mod_fini(void)
 {
-	crypto_unregister_shash(&alg);
+	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
+
 }
 
 subsys_initcall(crc32_mod_init);
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index ee8da628e9da..e0d6bfcc13e6 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -4692,6 +4692,7 @@ static const struct alg_test_desc alg_test_descs[] = {
 		.test = alg_test_null,
 	}, {
 		.alg = "crc32",
+		.generic_driver = "crc32-base",
 		.test = alg_test_hash,
 		.fips_allowed = 1,
 		.suite = {
-- 
2.47.0.rc1.288.g06298d1525-goog