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Fix performance regression in SSL handshake #66077

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Merged
merged 2 commits into from
Mar 7, 2022
Merged

Fix performance regression in SSL handshake #66077

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bd62f07
Fix performance regression in SSL handshake
rzikm Mar 2, 2022
55db46b
Further optimizations
rzikm Mar 3, 2022
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10 changes: 5 additions & 5 deletions src/libraries/System.Net.Security/src/System/Net/CertificateValidationPal.Windows.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,12 +48,12 @@ internal static SslPolicyErrors VerifyCertificateProperties(
SafeFreeCertContext? remoteContext = null;
try
{
// SECPKG_ATTR_REMOTE_CERT_CHAIN can be used even before the TLS handshake completes, which is necessary
// in order to supply the certificate to the client cert selection callback. However, it is not available on
// windows 7, so use the SECPKG_ATTR_REMOTE_CERT_CONTEXT as a fallback option.
if (!SSPIWrapper.QueryContextAttributes_SECPKG_ATTR_REMOTE_CERT_CHAIN(GlobalSSPI.SSPISecureChannel, securityContext, out remoteContext))
if (!SSPIWrapper.QueryContextAttributes_SECPKG_ATTR_REMOTE_CERT_CONTEXT(GlobalSSPI.SSPISecureChannel, securityContext, out remoteContext))
{
SSPIWrapper.QueryContextAttributes_SECPKG_ATTR_REMOTE_CERT_CONTEXT(GlobalSSPI.SSPISecureChannel, securityContext, out remoteContext);
// The query can fail if TLS handshake has not completed yet. In that case we fallback to querying
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@stephentoub stephentoub Mar 2, 2022

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I assume we expect this to be rare?

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@rzikm rzikm Mar 3, 2022 •
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AFAIK the only case when we need the remote cert before handshake completes is during the second call of the LocalClientCertificateSelectionCallback, which provides acceptable issuers and the server certificate as arguments. So the conditions for that happening should be:

  • Server requires client certificate
  • Client uses LocalClientCertificateSelectionCallback which during the first call returns null or a cert which does not match trusted issuers required by server.

I don't know how common that usage is, but since not many people complained that until #65134 the server cert was always null on Windows then I suppose it is indeed rare.

// SECPKG_ATTR_REMOTE_CERT_CHAIN that is more expensive but works even during handshake.
// Note: On Windows versions which don't support querying CERT_CHAIN, we fail and always return null
SSPIWrapper.QueryContextAttributes_SECPKG_ATTR_REMOTE_CERT_CHAIN(GlobalSSPI.SSPISecureChannel, securityContext, out remoteContext);
}

if (remoteContext != null && !remoteContext.IsInvalid)
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