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

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Message-ID: <03cfdcc9-716f-4690-b400-c8da59ca1ef6@thson.de>
Date:   Mon, 21 Aug 2023 13:30:15 +0300
From:   Thore Sommer <public@...on.de>
To:     Jarkko Sakkinen <jarkko@...nel.org>, dhowells@...hat.com,
        herbert@...dor.apana.org.au, davem@...emloft.net
Cc:     keyrings@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] X.509: if signature is unsupported skip validation

On 16.08.23 23:54, Jarkko Sakkinen wrote:
> 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@...on.de>
>> ---
>>   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@...r.kernel.org # v4.7+
> Fixes: 6c2dc5ae4ab7 ("X.509: Extract signature digest and make self-signed cert checks earlier")
> 
> BR, Jarkko

Hi Jarkko,

should I resend it with the stable mailing list in CC or will it be 
added when a maintainer includes the change?

Best regards,
Thore