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>

3 files changed, 6 insertions, 23 deletions

diff --git a/drivers/crypto/ccree/cc_aead.c b/drivers/crypto/ccree/cc_aead.c
index b0085db7e211..d014c8e063a7 100644
--- a/drivers/crypto/ccree/cc_aead.c
+++ b/drivers/crypto/ccree/cc_aead.c
@@ -562,7 +562,7 @@ static int cc_aead_setkey(struct crypto_aead *tfm, const u8 *key,
 
 		rc = crypto_authenc_extractkeys(&keys, key, keylen);
 		if (rc)
-			goto badkey;
+			return rc;
 		enckey = keys.enckey;
 		authkey = keys.authkey;
 		ctx->enc_keylen = keys.enckeylen;
@@ -570,10 +570,9 @@ static int cc_aead_setkey(struct crypto_aead *tfm, const u8 *key,
 
 		if (ctx->cipher_mode == DRV_CIPHER_CTR) {
 			/* the nonce is stored in bytes at end of key */
-			rc = -EINVAL;
 			if (ctx->enc_keylen <
 			    (AES_MIN_KEY_SIZE + CTR_RFC3686_NONCE_SIZE))
-				goto badkey;
+				return -EINVAL;
 			/* Copy nonce from last 4 bytes in CTR key to
 			 *  first 4 bytes in CTR IV
 			 */
@@ -591,7 +590,7 @@ static int cc_aead_setkey(struct crypto_aead *tfm, const u8 *key,
 
 	rc = validate_keys_sizes(ctx);
 	if (rc)
-		goto badkey;
+		return rc;
 
 	/* STAT_PHASE_1: Copy key to ctx */
 
@@ -605,7 +604,7 @@ static int cc_aead_setkey(struct crypto_aead *tfm, const u8 *key,
 	} else if (ctx->auth_mode != DRV_HASH_NULL) { /* HMAC */
 		rc = cc_get_plain_hmac_key(tfm, authkey, ctx->auth_keylen);
 		if (rc)
-			goto badkey;
+			return rc;
 	}
 
 	/* STAT_PHASE_2: Create sequence */
@@ -622,8 +621,7 @@ static int cc_aead_setkey(struct crypto_aead *tfm, const u8 *key,
 		break; /* No auth. key setup */
 	default:
 		dev_err(dev, "Unsupported authenc (%d)\n", ctx->auth_mode);
-		rc = -ENOTSUPP;
-		goto badkey;
+		return -ENOTSUPP;
 	}
 
 	/* STAT_PHASE_3: Submit sequence to HW */
@@ -632,18 +630,12 @@ static int cc_aead_setkey(struct crypto_aead *tfm, const u8 *key,
 		rc = cc_send_sync_request(ctx->drvdata, &cc_req, desc, seq_len);
 		if (rc) {
 			dev_err(dev, "send_request() failed (rc=%d)\n", rc);
-			goto setkey_error;
+			return rc;
 		}
 	}
 
 	/* Update STAT_PHASE_3 */
 	return rc;
-
-badkey:
-	crypto_aead_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
-
-setkey_error:
-	return rc;
 }
 
 static int cc_des3_aead_setkey(struct crypto_aead *aead, const u8 *key,
diff --git a/drivers/crypto/ccree/cc_cipher.c b/drivers/crypto/ccree/cc_cipher.c
index 61b9dcaa0c05..7493a32f12b9 100644
--- a/drivers/crypto/ccree/cc_cipher.c
+++ b/drivers/crypto/ccree/cc_cipher.c
@@ -291,7 +291,6 @@ static int cc_cipher_sethkey(struct crypto_skcipher *sktfm, const u8 *key,
 	/* This check the size of the protected key token */
 	if (keylen != sizeof(hki)) {
 		dev_err(dev, "Unsupported protected key size %d.\n", keylen);
-		crypto_tfm_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
 		return -EINVAL;
 	}
 
@@ -304,7 +303,6 @@ static int cc_cipher_sethkey(struct crypto_skcipher *sktfm, const u8 *key,
 
 	if (validate_keys_sizes(ctx_p, keylen)) {
 		dev_err(dev, "Unsupported key size %d.\n", keylen);
-		crypto_tfm_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
 		return -EINVAL;
 	}
 
@@ -395,7 +393,6 @@ static int cc_cipher_setkey(struct crypto_skcipher *sktfm, const u8 *key,
 
 	if (validate_keys_sizes(ctx_p, keylen)) {
 		dev_err(dev, "Unsupported key size %d.\n", keylen);
-		crypto_tfm_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
 		return -EINVAL;
 	}
 
diff --git a/drivers/crypto/ccree/cc_hash.c b/drivers/crypto/ccree/cc_hash.c
index aee5db5f8538..912e5ce5079d 100644
--- a/drivers/crypto/ccree/cc_hash.c
+++ b/drivers/crypto/ccree/cc_hash.c
@@ -899,9 +899,6 @@ static int cc_hash_setkey(struct crypto_ahash *ahash, const u8 *key,
 	rc = cc_send_sync_request(ctx->drvdata, &cc_req, desc, idx);
 
 out:
-	if (rc)
-		crypto_ahash_set_flags(ahash, CRYPTO_TFM_RES_BAD_KEY_LEN);
-
 	if (ctx->key_params.key_dma_addr) {
 		dma_unmap_single(dev, ctx->key_params.key_dma_addr,
 				 ctx->key_params.keylen, DMA_TO_DEVICE);
@@ -990,9 +987,6 @@ static int cc_xcbc_setkey(struct crypto_ahash *ahash,
 
 	rc = cc_send_sync_request(ctx->drvdata, &cc_req, desc, idx);
 
-	if (rc)
-		crypto_ahash_set_flags(ahash, CRYPTO_TFM_RES_BAD_KEY_LEN);
-
 	dma_unmap_single(dev, ctx->key_params.key_dma_addr,
 			 ctx->key_params.keylen, DMA_TO_DEVICE);
 	dev_dbg(dev, "Unmapped key-buffer: key_dma_addr=%pad keylen=%u\n",