phase1b: add Win32k disable mitigation constant#290
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Introduces a Windows-only constants/helper module exposing the PROCESS_CREATION_MITIGATION_POLICY_WIN32K_SYSTEM_CALL_DISABLE_ALWAYS_ON mitigation flag (1 << 28 from winnt.h), which is documented in the Windows SDK but is not generated into the `windows` crate metadata. If a future `windows` crate release adds it, this module becomes redundant and can be deleted. The companion attribute identifier PROC_THREAD_ATTRIBUTE_MITIGATION_POLICY is already available from windows::Win32::System::Threading and is used directly at call sites (cast to usize because UpdateProcThreadAttribute's dwAttribute parameter is DWORD_PTR). Provides a win32k_disable_value() helper and a unit test verifying the documented bit position. No callers yet; this prepares for AppContainer Phase 1 integration where UpdateProcThreadAttribute will apply the mitigation before the child's first user-mode instruction. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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shschaefer
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May 12, 2026
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📖 Description
Introduces a Windows-only constants/helper module exposing the
PROCESS_CREATION_MITIGATION_POLICY_WIN32K_SYSTEM_CALL_DISABLE_ALWAYS_ONmitigation flag (1 << 28fromwinnt.h), which is documented in the Windows SDK but is not generated into thewindowscrate metadata. If a futurewindowscrate release adds it, this module becomes redundant and can be deleted.The companion attribute identifier
PROC_THREAD_ATTRIBUTE_MITIGATION_POLICYis already available fromwindows::Win32::System::Threading(theWin32_System_Threadingfeature is enabled at the workspace level), so it is used directly at call sites — cast tousizebecauseUpdateProcThreadAttribute'sdwAttributeparameter isDWORD_PTR.Provides a
win32k_disable_value()helper and a unit test verifying the documented bit position.No callers yet — this prepares for AppContainer Phase 1 integration where
UpdateProcThreadAttributewill apply the mitigation before the child's first user-mode instruction.🔗 References
Next in the downlevel-fallback stack: phase1c (#291).
🔍 Validation
cargo test -p wxc_common --lib process_mitigationpassescargo build -p wxc_commoncleanWin25H2Safe-Tests.ps1in phase5 (held)