From: Ard Biesheuvel <a...@kernel.org> Shim's PE loader uses the EFI memory attributes protocol in a way that results in an immediate crash when invoking the loaded image, unless the base and size of its executable segment are both aligned to 4k.
If this is not the case, it will strip the memory allocation of its executable permissions, but fail to add them back for the executable region, resulting in non-executable code. Unfortunately, the PE loader does not even bother invoking the protocol in this case (as it notices the misalignment), making it very hard for system firmware to work around this by attempting to infer the intent of the caller. So let's introduce a QEMU command line option to indicate that the protocol should not be exposed at all, and a PCD to set the default for this option when it is omitted. -fw_cfg opt/org.tianocore/UninstallMemAttrProtocol,string=y Cc: Laszlo Ersek <ler...@redhat.com> Cc: Gerd Hoffmann <kra...@redhat.com> Cc: Oliver Steffen <ostef...@redhat.com> Cc: Alexander Graf <g...@amazon.com> Cc: Oliver Smith-Denny <o...@linux.microsoft.com> Cc: Taylor Beebe <taylor.d.be...@gmail.com> Cc: Peter Jones <pjo...@redhat.com> Cc: Leif Lindholm <quic_llind...@quicinc.com> Link: https://gitlab.com/qemu-project/qemu/-/issues/1990 Signed-off-by: Ard Biesheuvel <a...@kernel.org> --- ArmVirtPkg/ArmVirtPkg.dec | 6 ++ ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf | 3 + ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBm.c | 62 ++++++++++++++++++++ 3 files changed, 71 insertions(+) diff --git a/ArmVirtPkg/ArmVirtPkg.dec b/ArmVirtPkg/ArmVirtPkg.dec index 0f2d7873279f..313aebda902a 100644 --- a/ArmVirtPkg/ArmVirtPkg.dec +++ b/ArmVirtPkg/ArmVirtPkg.dec @@ -68,3 +68,9 @@ [PcdsFixedAtBuild, PcdsPatchableInModule] # Cloud Hypervisor has no other way to pass Rsdp address to the guest except use a PCD. # gArmVirtTokenSpaceGuid.PcdCloudHvAcpiRsdpBaseAddress|0x0|UINT64|0x00000005 + + ## + # Whether the EFI memory attributes protocol should be uninstalled before + # invoking the OS loader. This may be needed to work around problematic + # builds of shim that use the protocol incorrectly. + gArmVirtTokenSpaceGuid.PcdUninstallMemAttrProtocol|FALSE|BOOLEAN|0x00000006 diff --git a/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf b/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf index 997eb1a4429f..70e4ebf94ad9 100644 --- a/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf +++ b/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf @@ -46,6 +46,7 @@ [LibraryClasses] PcdLib PlatformBmPrintScLib QemuBootOrderLib + QemuFwCfgSimpleParserLib QemuLoadImageLib ReportStatusCodeLib TpmPlatformHierarchyLib @@ -55,6 +56,7 @@ [LibraryClasses] UefiRuntimeServicesTableLib [FixedPcd] + gArmVirtTokenSpaceGuid.PcdUninstallMemAttrProtocol gEfiMdePkgTokenSpaceGuid.PcdUartDefaultBaudRate gEfiMdePkgTokenSpaceGuid.PcdUartDefaultDataBits gEfiMdePkgTokenSpaceGuid.PcdUartDefaultParity @@ -73,5 +75,6 @@ [Guids] [Protocols] gEfiFirmwareVolume2ProtocolGuid gEfiGraphicsOutputProtocolGuid + gEfiMemoryAttributeProtocolGuid gEfiPciRootBridgeIoProtocolGuid gVirtioDeviceProtocolGuid diff --git a/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBm.c b/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBm.c index 85c01351b09d..a1a2bca2af3d 100644 --- a/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBm.c +++ b/ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBm.c @@ -16,6 +16,7 @@ #include <Library/PcdLib.h> #include <Library/PlatformBmPrintScLib.h> #include <Library/QemuBootOrderLib.h> +#include <Library/QemuFwCfgSimpleParserLib.h> #include <Library/TpmPlatformHierarchyLib.h> #include <Library/UefiBootManagerLib.h> #include <Protocol/DevicePath.h> @@ -1111,6 +1112,49 @@ PlatformBootManagerBeforeConsole ( FilterAndProcess (&gEfiPciIoProtocolGuid, IsVirtioPciSerial, SetupVirtioSerial); } +/** + Uninstall the EFI memory attribute protocol if it exists. +**/ +STATIC +VOID +UninstallEfiMemoryAttributesProtocol ( + VOID + ) +{ + EFI_STATUS Status; + EFI_HANDLE Handle; + UINTN Size; + VOID *MemoryAttributeProtocol; + + Size = sizeof (Handle); + Status = gBS->LocateHandle ( + ByProtocol, + &gEfiMemoryAttributeProtocolGuid, + NULL, + &Size, + &Handle + ); + + if (EFI_ERROR (Status)) { + ASSERT (Status == EFI_NOT_FOUND); + return; + } + + Status = gBS->HandleProtocol ( + Handle, + &gEfiMemoryAttributeProtocolGuid, + &MemoryAttributeProtocol + ); + ASSERT_EFI_ERROR (Status); + + Status = gBS->UninstallProtocolInterface ( + Handle, + &gEfiMemoryAttributeProtocolGuid, + MemoryAttributeProtocol + ); + ASSERT_EFI_ERROR (Status); +} + /** Do the platform specific action after the console is ready Possible things that can be done in PlatformBootManagerAfterConsole: @@ -1129,12 +1173,30 @@ PlatformBootManagerAfterConsole ( ) { RETURN_STATUS Status; + BOOLEAN Uninstall; // // Show the splash screen. // BootLogoEnableLogo (); + // + // Work around shim's terminally broken use of the EFI memory attributes + // protocol, by uninstalling it if requested on the QEMU command line. + // + // E.g., + // -fw_cfg opt/org.tianocore/UninstallMemAttrProtocol,string=y + // + // This is only needed on the first boot, when fbaa64.efi is being invoked to + // set the boot order variables. Subsequent boots involving GRUB are not + // affected. + // + Uninstall = FixedPcdGetBool (PcdUninstallMemAttrProtocol); + QemuFwCfgParseBool ("opt/org.tianocore/UninstallMemAttrProtocol", &Uninstall); + if (Uninstall) { + UninstallEfiMemoryAttributesProtocol (); + } + // // Process QEMU's -kernel command line option. The kernel booted this way // will receive ACPI tables: in PlatformBootManagerBeforeConsole(), we -- 2.43.0.472.g3155946c3a-goog -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#112289): https://edk2.groups.io/g/devel/message/112289 Mute This Topic: https://groups.io/mt/103106391/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
