[release-branch.go1.15] crypto/tls: test key type when casting
When casting the certificate public key in generateClientKeyExchange,
check the type is appropriate. This prevents a panic when a server
agrees to a RSA based key exchange, but then sends an ECDSA (or
other) certificate.
Updates #47143
Fixes #47144
Fixes CVE-2021-34558
Thanks to Imre Rad for reporting this issue.
Change-Id: Iabccacca6052769a605cccefa1216a9f7b7f6aea
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1116723
Reviewed-by: Filippo Valsorda <valsorda@google.com>
Reviewed-by: Katie Hockman <katiehockman@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/334030
Trust: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/src/crypto/tls/key_agreement.go b/src/crypto/tls/key_agreement.go
index 7e6534b..22f1b2e 100644
--- a/src/crypto/tls/key_agreement.go
+++ b/src/crypto/tls/key_agreement.go
@@ -67,7 +67,11 @@
return nil, nil, err
}
- encrypted, err := rsa.EncryptPKCS1v15(config.rand(), cert.PublicKey.(*rsa.PublicKey), preMasterSecret)
+ rsaKey, ok := cert.PublicKey.(*rsa.PublicKey)
+ if !ok {
+ return nil, nil, errors.New("tls: server certificate contains incorrect key type for selected ciphersuite")
+ }
+ encrypted, err := rsa.EncryptPKCS1v15(config.rand(), rsaKey, preMasterSecret)
if err != nil {
return nil, nil, err
}
