crypto: hash - annotate algorithms taking optional key

commit a208fa8f33031b9e0aba44c7d1b7e68eb0cbd29e upstream.

We need to consistently enforce that keyed hashes cannot be used without
setting the key.  To do this we need a reliable way to determine whether
a given hash algorithm is keyed or not.  AF_ALG currently does this by
checking for the presence of a ->setkey() method.  However, this is
actually slightly broken because the CRC-32 algorithms implement
->setkey() but can also be used without a key.  (The CRC-32 "key" is not
actually a cryptographic key but rather represents the initial state.
If not overridden, then a default initial state is used.)

Prepare to fix this by introducing a flag CRYPTO_ALG_OPTIONAL_KEY which
indicates that the algorithm has a ->setkey() method, but it is not
required to be called.  Then set it on all the CRC-32 algorithms.

The same also applies to the Adler-32 implementation in Lustre.

Also, the cryptd and mcryptd templates have to pass through the flag
from their underlying algorithm.

Change-Id: Ie0547047b828f276d967e8979cd9176e57c99ac8
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[bwh: Backported to 3.2:
 - Drop changes to nonexistent drivers
 - There's no CRYPTO_ALG_INTERNAL flag
 - Adjust filenames]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/arm64/crypto/crc32-arm64.c

@@ -232,6 +232,7 @@ static struct shash_alg crc32_alg = {
 		.cra_name		=	"crc32",
 		.cra_driver_name	=	"crc32-arm64-hw",
 		.cra_priority		=	300,
+		.cra_flags		=	CRYPTO_ALG_OPTIONAL_KEY,
 		.cra_blocksize		=	CHKSUM_BLOCK_SIZE,
 		.cra_alignmask		=	0,
 		.cra_ctxsize		=	sizeof(struct chksum_ctx),
@@ -253,6 +254,7 @@ static struct shash_alg crc32c_alg = {
 		.cra_name		=	"crc32c",
 		.cra_driver_name	=	"crc32c-arm64-hw",
 		.cra_priority		=	300,
+		.cra_flags		=	CRYPTO_ALG_OPTIONAL_KEY,
 		.cra_blocksize		=	CHKSUM_BLOCK_SIZE,
 		.cra_alignmask		=	0,
 		.cra_ctxsize		=	sizeof(struct chksum_ctx),

arch/sparc/crypto/crc32c_glue.c

@@ -133,6 +133,7 @@ static struct shash_alg alg = {
 		.cra_name		=	"crc32c",
 		.cra_driver_name	=	"crc32c-sparc64",
 		.cra_priority		=	SPARC_CR_OPCODE_PRIORITY,
+		.cra_flags		=	CRYPTO_ALG_OPTIONAL_KEY,
 		.cra_blocksize		=	CHKSUM_BLOCK_SIZE,
 		.cra_ctxsize		=	sizeof(u32),
 		.cra_alignmask		=	7,

arch/x86/crypto/crc32-pclmul_glue.c

@@ -162,6 +162,7 @@ static struct shash_alg alg = {
 			.cra_name		= "crc32",
 			.cra_driver_name	= "crc32-pclmul",
 			.cra_priority		= 200,
+			.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
 			.cra_blocksize		= CHKSUM_BLOCK_SIZE,
 			.cra_ctxsize		= sizeof(u32),
 			.cra_module		= THIS_MODULE,

arch/x86/crypto/crc32c-intel_glue.c

@@ -240,6 +240,7 @@ static struct shash_alg alg = {
 		.cra_name		=	"crc32c",
 		.cra_driver_name	=	"crc32c-intel",
 		.cra_priority		=	200,
+		.cra_flags		=	CRYPTO_ALG_OPTIONAL_KEY,
 		.cra_blocksize		=	CHKSUM_BLOCK_SIZE,
 		.cra_ctxsize		=	sizeof(u32),
 		.cra_module		=	THIS_MODULE,

crypto/crc32.c

@@ -133,6 +133,7 @@ static struct shash_alg alg = {
 		.cra_name		= "crc32",
 		.cra_driver_name	= "crc32-table",
 		.cra_priority		= 100,
+		.cra_flags              = CRYPTO_ALG_OPTIONAL_KEY,
 		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
 		.cra_ctxsize		= sizeof(u32),
 		.cra_module		= THIS_MODULE,

crypto/crc32c.c

@@ -146,6 +146,7 @@ static struct shash_alg alg = {
 		.cra_name		=	"crc32c",
 		.cra_driver_name	=	"crc32c-generic",
 		.cra_priority		=	100,
+		.cra_flags		=	CRYPTO_ALG_OPTIONAL_KEY,
 		.cra_blocksize		=	CHKSUM_BLOCK_SIZE,
 		.cra_alignmask		=	3,
 		.cra_ctxsize		=	sizeof(struct chksum_ctx),

crypto/cryptd.c

@@ -603,7 +603,8 @@ static int cryptd_create_hash(struct crypto_template *tmpl, struct rtattr **tb,
 	if (err)
 		goto out_free_inst;
 
-	inst->alg.halg.base.cra_flags = CRYPTO_ALG_ASYNC;
+	inst->alg.halg.base.cra_flags = CRYPTO_ALG_ASYNC |
+		(alg->cra_flags & CRYPTO_ALG_OPTIONAL_KEY);
 
 	inst->alg.halg.digestsize = salg->digestsize;
 	inst->alg.halg.statesize = salg->statesize;

drivers/crypto/bfin_crc.c

@@ -516,7 +516,8 @@ static struct ahash_alg algs = {
 		.cra_driver_name	= DRIVER_NAME,
 		.cra_priority		= 100,
 		.cra_flags		= CRYPTO_ALG_TYPE_AHASH |
-						CRYPTO_ALG_ASYNC,
+						CRYPTO_ALG_ASYNC |
+						CRYPTO_ALG_OPTIONAL_KEY,
 		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
 		.cra_ctxsize		= sizeof(struct bfin_crypto_crc_ctx),
 		.cra_alignmask		= 3,

include/linux/crypto.h

@@ -94,6 +94,12 @@
  */
 #define CRYPTO_ALG_KERN_DRIVER_ONLY	0x00001000
 
+/*
+ * Set if the algorithm has a ->setkey() method but can be used without
+ * calling it first, i.e. there is a default key.
+ */
+#define CRYPTO_ALG_OPTIONAL_KEY		0x00004000
+
 /*
  * Transform masks and values (for crt_flags).
  */