HttpSys: fail startup when Strict hardening cannot be applied

[DeagleGross]

Follow-up to #67436 addressing #67436 (comment).

When HttpAuthenticationHardeningLevel.Strict is configured, the caller is asking for a hard security guarantee (reject authenticated requests that lack a valid channel binding token). Silently degrading to the OS default hardening on a SetProperty failure is misleading, so throw and fail startup instead.

Legacy/Medium continue to log-and-continue via Log.SetUrlPropertyError, matching the previous behavior.

Change

UrlGroup.SetChannelBindingProperty now calls SetProperty(..., throwOnError: level == HttpAuthenticationHardeningLevel.Strict).

Notes

• The OS floor for HttpServerChannelBindProperty is Windows 7 / Server 2008 R2, so failure on a supported OS realistically only happens under kernel policy/ACL restrictions or test shims.
• No behavior change for the default Medium level.

[Copilot]

Pull request overview

This PR tightens HttpSys startup behavior when HttpAuthenticationHardeningLevel.Strict is configured by ensuring the server fails fast if the underlying HttpServerChannelBindProperty cannot be applied, avoiding a misleading “best effort” security configuration in a strict mode.

Changes:

• Make UrlGroup.SetChannelBindingProperty throw on HttpSetUrlGroupProperty failures when hardening level is Strict.
• Keep existing log-and-continue behavior for Legacy and Medium.
• Add inline rationale documenting why Strict is treated as a hard requirement.

Show a summary per file

File	Description
src/Servers/HttpSys/src/NativeInterop/UrlGroup.cs	Changes SetChannelBindingProperty to fail startup on property-apply failures when Strict is configured.

Copilot's findings

Comments suppressed due to low confidence (1)

src/Servers/HttpSys/src/NativeInterop/UrlGroup.cs:53

• The new comment says this path is "silently degrading" on failure, but SetProperty logs an error even when throwOnError is false. Consider rewording to avoid implying the failure is silent and to state explicitly that the OS default hardening remains in effect when the property can't be applied.

    internal unsafe void SetChannelBindingProperty(HttpAuthenticationHardeningLevel level)
    {
        var info = new HTTP_CHANNEL_BIND_INFO
        {

• Files reviewed: 1/1 changed files
• Comments generated: 0