On 6/6/20 1:52 AM, Laszlo Ersek wrote:
When an image fails Secure Boot validation, LoadImage() returns
EFI_SECURITY_VIOLATION if the platform policy is
DEFER_EXECUTE_ON_SECURITY_VIOLATION.
If the platform policy is DENY_EXECUTE_ON_SECURITY_VIOLATION, then
LoadImage() returns EFI_ACCESS_DENIED (and the image does not remain
loaded).
(Before <https://bugzilla.tianocore.org/show_bug.cgi?id=2129>, this
difference would be masked, as DxeImageVerificationLib would incorrectly
return EFI_SECURITY_VIOLATION for DENY_EXECUTE_ON_SECURITY_VIOLATION as
well.)
In X86QemuLoadImageLib, proceed to the legacy Linux/x86 Boot Protocol upon
seeing EFI_ACCESS_DENIED too.
Cc: Ard Biesheuvel <ard.biesheu...@arm.com>
Cc: Jordan Justen <jordan.l.jus...@intel.com>
Cc: Philippe Mathieu-Daudé <phi...@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2785
Signed-off-by: Laszlo Ersek <ler...@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheu...@arm.com>
---
Notes:
Repo: https://pagure.io/lersek/edk2.git
Branch: x86_qlil_access_denied
OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c
b/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c
index ef753be7ea90..931553c0c1fb 100644
--- a/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c
+++ b/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c
@@ -319,13 +319,19 @@ QemuLoadKernelImage (
return EFI_NOT_FOUND;
case EFI_SECURITY_VIOLATION:
+ //
+ // Since the image has been loaded, we need to unload it before proceeding
+ // to the EFI_ACCESS_DENIED case below.
+ //
+ gBS->UnloadImage (KernelImageHandle);
+ //
+ // Fall through
+ //
+ case EFI_ACCESS_DENIED:
//
// We are running with UEFI secure boot enabled, and the image failed to
// authenticate. For compatibility reasons, we fall back to the legacy
- // loader in this case. Since the image has been loaded, we need to unload
- // it before proceeding
- //
- gBS->UnloadImage (KernelImageHandle);
+ // loader in this case.
//
// Fall through
//
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