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authorDenis Kenzior <denkenz@gmail.com>2022-08-26 09:51:19 -0500
committerJarkko Sakkinen <jarkko@kernel.org>2023-02-13 10:11:20 +0200
commit10de7b54293995368c52d9aa153f3e7a359f04a1 (patch)
treeb93a672b3acc4afe73d3990378efe17a46ebe543 /crypto/asymmetric_keys/public_key.c
parentc95e8f6fd157b45ef0685c221931561e943e82da (diff)
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: 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>
Diffstat (limited to 'crypto/asymmetric_keys/public_key.c')
-rw-r--r--crypto/asymmetric_keys/public_key.c24
1 files changed, 22 insertions, 2 deletions
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 2f8352e88860..eca5671ad3f2 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 |