crypto: ecdsa - Adjust tests on length of key parameters

In preparation for support of NIST P521, adjust the basic tests on the
length of the provided key parameters to only ensure that the length of the
x plus y coordinates parameter array is not an odd number and that each
coordinate fits into an array of 'ndigits' digits. Mathematical tests on
the key's parameters are then done in ecc_is_pubkey_valid_full rejecting
invalid keys.

The change is necessary since NIST P521 keys do not have keys with
coordinates that each require 'full' digits (= all bits in u64 used).
NIST P521 only requires 2 bytes (9 bits) in the most significant digit
unlike NIST P192/256/384 that each require multiple 'full' digits.

Tested-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
index e819d0983bd39dbde7ac989e7a3dd53ecdb666f0..9462a4d640a7d6dda27b73aa041fded85993a2e7 100644 (file)
--- a/crypto/ecdsa.c
+++ b/crypto/ecdsa.c
@@ -230,7 +230,7 @@ static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsig
        if (ret < 0)
                return ret;
 
-       if (keylen < 1 || (((keylen - 1) >> 1) % sizeof(u64)) != 0)
+       if (keylen < 1 || ((keylen - 1) & 1) != 0)
                return -EINVAL;
        /* we only accept uncompressed format indicated by '4' */
        if (d[0] != 4)