Re: [PATCH] X.509: if signature is unsupported skip validation

[Jarkko Sakkinen]

On Tue Aug 15, 2023 at 2:29 PM EEST, Thore Sommer wrote:
> 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@xxxxxxxx>
> ---
>  crypto/asymmetric_keys/x509_public_key.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
> index 6fdfc82e23a8..7c71db3ac23d 100644
> --- 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) {
> -- 
> 2.41.0

Should have:

Cc: stable@xxxxxxxxxxxxxxx # v4.7+
Fixes: 6c2dc5ae4ab7 ("X.509: Extract signature digest and make self-signed cert checks earlier")

BR, Jarkko