crypto: remove CRYPTO_TFM_RES_BAD_KEY_LEN

The CRYPTO_TFM_RES_BAD_KEY_LEN flag was apparently meant as a way to
make the ->setkey() functions provide more information about errors.

However, no one actually checks for this flag, which makes it pointless.

Also, many algorithms fail to set this flag when given a bad length key.
Reviewing just the generic implementations, this is the case for
aes-fixed-time, cbcmac, echainiv, nhpoly1305, pcrypt, rfc3686, rfc4309,
rfc7539, rfc7539esp, salsa20, seqiv, and xcbc.  But there are probably
many more in arch/*/crypto/ and drivers/crypto/.

Some algorithms can even set this flag when the key is the correct
length.  For example, authenc and authencesn set it when the key payload
is malformed in any way (not just a bad length), the atmel-sha and ccree
drivers can set it if a memory allocation fails, and the chelsio driver
sets it for bad auth tag lengths, not just bad key lengths.

So even if someone actually wanted to start checking this flag (which
seems unlikely, since it's been unused for a long time), there would be
a lot of work needed to get it working correctly.  But it would probably
be much better to go back to the drawing board and just define different
return values, like -EINVAL if the key is invalid for the algorithm vs.
-EKEYREJECTED if the key was rejected by a policy like "no weak keys".
That would be much simpler, less error-prone, and easier to test.

So just remove this flag.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 11 insertions, 33 deletions

diff --git a/drivers/crypto/caam/caamalg_qi.c b/drivers/crypto/caam/caamalg_qi.c
index 8e3449670d2f..4a29e0ef9d63 100644
--- a/drivers/crypto/caam/caamalg_qi.c
+++ b/drivers/crypto/caam/caamalg_qi.c
@@ -268,7 +268,6 @@ skip_split_key:
 	memzero_explicit(&keys, sizeof(keys));
 	return ret;
 badkey:
-	crypto_aead_set_flags(aead, CRYPTO_TFM_RES_BAD_KEY_LEN);
 	memzero_explicit(&keys, sizeof(keys));
 	return -EINVAL;
 }
@@ -356,10 +355,8 @@ static int gcm_setkey(struct crypto_aead *aead,
 	int ret;
 
 	ret = aes_check_keylen(keylen);
-	if (ret) {
-		crypto_aead_set_flags(aead, CRYPTO_TFM_RES_BAD_KEY_LEN);
+	if (ret)
 		return ret;
-	}
 
 	print_hex_dump_debug("key in @" __stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, key, keylen, 1);
@@ -462,10 +459,8 @@ static int rfc4106_setkey(struct crypto_aead *aead,
 	int ret;
 
 	ret = aes_check_keylen(keylen - 4);
-	if (ret) {
-		crypto_aead_set_flags(aead, CRYPTO_TFM_RES_BAD_KEY_LEN);
+	if (ret)
 		return ret;
-	}
 
 	print_hex_dump_debug("key in @" __stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, key, keylen, 1);
@@ -570,10 +565,8 @@ static int rfc4543_setkey(struct crypto_aead *aead,
 	int ret;
 
 	ret = aes_check_keylen(keylen - 4);
-	if (ret) {
-		crypto_aead_set_flags(aead, CRYPTO_TFM_RES_BAD_KEY_LEN);
+	if (ret)
 		return ret;
-	}
 
 	print_hex_dump_debug("key in @" __stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, key, keylen, 1);
@@ -644,7 +637,7 @@ static int skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 					  ctx->sh_desc_enc);
 		if (ret) {
 			dev_err(jrdev, "driver enc context update failed\n");
-			goto badkey;
+			return -EINVAL;
 		}
 	}
 
@@ -653,14 +646,11 @@ static int skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 					  ctx->sh_desc_dec);
 		if (ret) {
 			dev_err(jrdev, "driver dec context update failed\n");
-			goto badkey;
+			return -EINVAL;
 		}
 	}
 
 	return ret;
-badkey:
-	crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_RES_BAD_KEY_LEN);
-	return -EINVAL;
 }
 
 static int aes_skcipher_setkey(struct crypto_skcipher *skcipher,
@@ -669,11 +659,8 @@ static int aes_skcipher_setkey(struct crypto_skcipher *skcipher,
 	int err;
 
 	err = aes_check_keylen(keylen);
-	if (err) {
-		crypto_skcipher_set_flags(skcipher,
-					  CRYPTO_TFM_RES_BAD_KEY_LEN);
+	if (err)
 		return err;
-	}
 
 	return skcipher_setkey(skcipher, key, keylen, 0);
 }
@@ -693,11 +680,8 @@ static int rfc3686_skcipher_setkey(struct crypto_skcipher *skcipher,
 	keylen -= CTR_RFC3686_NONCE_SIZE;
 
 	err = aes_check_keylen(keylen);
-	if (err) {
-		crypto_skcipher_set_flags(skcipher,
-					  CRYPTO_TFM_RES_BAD_KEY_LEN);
+	if (err)
 		return err;
-	}
 
 	return skcipher_setkey(skcipher, key, keylen, ctx1_iv_off);
 }
@@ -716,11 +700,8 @@ static int ctr_skcipher_setkey(struct crypto_skcipher *skcipher,
 	ctx1_iv_off = 16;
 
 	err = aes_check_keylen(keylen);
-	if (err) {
-		crypto_skcipher_set_flags(skcipher,
-					  CRYPTO_TFM_RES_BAD_KEY_LEN);
+	if (err)
 		return err;
-	}
 
 	return skcipher_setkey(skcipher, key, keylen, ctx1_iv_off);
 }
@@ -748,7 +729,7 @@ static int xts_skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 
 	if (keylen != 2 * AES_MIN_KEY_SIZE  && keylen != 2 * AES_MAX_KEY_SIZE) {
 		dev_err(jrdev, "key size mismatch\n");
-		goto badkey;
+		return -EINVAL;
 	}
 
 	ctx->cdata.keylen = keylen;
@@ -765,7 +746,7 @@ static int xts_skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 					  ctx->sh_desc_enc);
 		if (ret) {
 			dev_err(jrdev, "driver enc context update failed\n");
-			goto badkey;
+			return -EINVAL;
 		}
 	}
 
@@ -774,14 +755,11 @@ static int xts_skcipher_setkey(struct crypto_skcipher *skcipher, const u8 *key,
 					  ctx->sh_desc_dec);
 		if (ret) {
 			dev_err(jrdev, "driver dec context update failed\n");
-			goto badkey;
+			return -EINVAL;
 		}
 	}
 
 	return ret;
-badkey:
-	crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_RES_BAD_KEY_LEN);
-	return -EINVAL;
 }
 
 /*