Commit 674f368a authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

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: default avatarEric Biggers <ebiggers@google.com>
Reviewed-by: default avatarHoria Geantă <horia.geanta@nxp.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 5c925e8b

arch/arm/crypto/aes-ce-glue.c

+2 −12
Original line number Diff line number Diff line
@@ -138,14 +138,8 @@ static int ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *in_key, 
			 unsigned int key_len)

{

	struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);

	int ret;



	ret = ce_aes_expandkey(ctx, in_key, key_len);

	if (!ret)

		return 0;



	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);

	return -EINVAL;

	return ce_aes_expandkey(ctx, in_key, key_len);

}



struct crypto_aes_xts_ctx {
@@ -167,11 +161,7 @@ static int xts_set_key(struct crypto_skcipher *tfm, const u8 *in_key, 
	if (!ret)

		ret = ce_aes_expandkey(&ctx->key2, &in_key[key_len / 2],

				       key_len / 2);

	if (!ret)

		return 0;



	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);

	return -EINVAL;

	return ret;

}



static int ecb_encrypt(struct skcipher_request *req)

arch/arm/crypto/crc32-ce-glue.c

+1 −3
Original line number Diff line number Diff line
@@ -54,10 +54,8 @@ static int crc32_setkey(struct crypto_shash *hash, const u8 *key, 
{

	u32 *mctx = crypto_shash_ctx(hash);



	if (keylen != sizeof(u32)) {

		crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);

	if (keylen != sizeof(u32))

		return -EINVAL;

	}

	*mctx = le32_to_cpup((__le32 *)key);

	return 0;

}

arch/arm/crypto/ghash-ce-glue.c

+1 −3
Original line number Diff line number Diff line
@@ -163,10 +163,8 @@ static int ghash_setkey(struct crypto_shash *tfm, 
	struct ghash_key *key = crypto_shash_ctx(tfm);

	be128 h;



	if (keylen != GHASH_BLOCK_SIZE) {

		crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);

	if (keylen != GHASH_BLOCK_SIZE)

		return -EINVAL;

	}



	/* needed for the fallback */

	memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);

arch/arm64/crypto/aes-ce-ccm-glue.c

+1 −7
Original line number Diff line number Diff line
@@ -47,14 +47,8 @@ static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key, 
		      unsigned int key_len)

{

	struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);

	int ret;



	ret = ce_aes_expandkey(ctx, in_key, key_len);

	if (!ret)

		return 0;



	tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;

	return -EINVAL;

	return ce_aes_expandkey(ctx, in_key, key_len);

}



static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)

arch/arm64/crypto/aes-ce-glue.c

+1 −7
Original line number Diff line number Diff line
@@ -143,14 +143,8 @@ int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key, 
		  unsigned int key_len)

{

	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);

	int ret;



	ret = ce_aes_expandkey(ctx, in_key, key_len);

	if (!ret)

		return 0;



	tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;

	return -EINVAL;

	return ce_aes_expandkey(ctx, in_key, key_len);

}

EXPORT_SYMBOL(ce_aes_setkey);