From: Denis Kenzior denkenz@gmail.com
[ Upstream commit 10de7b54293995368c52d9aa153f3e7a359f04a1 ]
When support for ECDSA keys was added, constraints for data & signature sizes were never updated. This makes it impossible to use such keys via keyctl API from userspace.
Update constraint on max_data_size to 64 bytes in order to support SHA512-based signatures. Also update the signature length constraints per ECDSA signature encoding described in RFC 5480.
Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys") Signed-off-by: Denis Kenzior denkenz@gmail.com Reviewed-by: Stefan Berger stefanb@linux.ibm.com Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- crypto/asymmetric_keys/public_key.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index 2f8352e888602..eca5671ad3f22 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -186,8 +186,28 @@ static int software_key_query(const struct kernel_pkey_params *params,
len = crypto_akcipher_maxsize(tfm); info->key_size = len * 8; - info->max_data_size = len; - info->max_sig_size = len; + + if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) { + /* + * ECDSA key sizes are much smaller than RSA, and thus could + * operate on (hashed) inputs that are larger than key size. + * For example SHA384-hashed input used with secp256r1 + * based keys. Set max_data_size to be at least as large as + * the largest supported hash size (SHA512) + */ + info->max_data_size = 64; + + /* + * Verify takes ECDSA-Sig (described in RFC 5480) as input, + * which is actually 2 'key_size'-bit integers encoded in + * ASN.1. Account for the ASN.1 encoding overhead here. + */ + info->max_sig_size = 2 * (len + 3) + 2; + } else { + info->max_data_size = len; + info->max_sig_size = len; + } + info->max_enc_size = len; info->max_dec_size = len; info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |