X.509: if signature is unsupported skip validation

When the hash algorithm for the signature is not available the digest size
is 0 and the signature in the certificate is marked as unsupported.

When validating a self-signed certificate, this needs to be checked,
because otherwise trying to validate the signature will fail with an
warning:

Loading compiled-in X.509 certificates
WARNING: CPU: 0 PID: 1 at crypto/rsa-pkcs1pad.c:537 \
pkcs1pad_verify+0x46/0x12c
...
Problem loading in-kernel X.509 certificate (-22)

Signed-off-by: Thore Sommer <public@thson.de>
Cc: stable@vger.kernel.org # v4.7+
Fixes: 6c2dc5ae4ab7 ("X.509: Extract signature digest and make self-signed cert checks earlier")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 6fdfc82e23a8afac7061f9947e194f5638a3096f..7c71db3ac23d487b36bc4b2c115d5dae4d15be6e 100644 (file)
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -130,6 +130,11 @@ int x509_check_for_self_signed(struct x509_certificate *cert)
                        goto out;
        }
 
+       if (cert->unsupported_sig) {
+               ret = 0;
+               goto out;
+       }
+
        ret = public_key_verify_signature(cert->pub, cert->sig);
        if (ret < 0) {
                if (ret == -ENOPKG) {