KEYS: asymmetric: Fix ECDSA use via keyctl uapi
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: 299f561a66
("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>
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@ -186,8 +186,28 @@ static int software_key_query(const struct kernel_pkey_params *params,
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len = crypto_akcipher_maxsize(tfm);
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len = crypto_akcipher_maxsize(tfm);
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info->key_size = len * 8;
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info->key_size = len * 8;
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info->max_data_size = len;
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info->max_sig_size = len;
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if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {
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/*
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* ECDSA key sizes are much smaller than RSA, and thus could
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* operate on (hashed) inputs that are larger than key size.
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* For example SHA384-hashed input used with secp256r1
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* based keys. Set max_data_size to be at least as large as
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* the largest supported hash size (SHA512)
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*/
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info->max_data_size = 64;
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/*
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* Verify takes ECDSA-Sig (described in RFC 5480) as input,
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* which is actually 2 'key_size'-bit integers encoded in
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* ASN.1. Account for the ASN.1 encoding overhead here.
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*/
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info->max_sig_size = 2 * (len + 3) + 2;
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} else {
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info->max_data_size = len;
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info->max_sig_size = len;
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}
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info->max_enc_size = len;
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info->max_enc_size = len;
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info->max_dec_size = len;
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info->max_dec_size = len;
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info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
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info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
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