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

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Message-ID: <20230815112942.392572-1-public@thson.de>
Date:   Tue, 15 Aug 2023 14:29:42 +0300
From:   Thore Sommer <public@...on.de>
To:     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, Thore Sommer <public@...on.de>
Subject: [PATCH] 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@...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