edk2/0019-ArmVirt-Allow-memory-attributes-protocol-to-be-disab.patch

From d93c63a8d3fe63f14b2c9e8dbf6792592fc9ea84 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Tue, 12 Dec 2023 09:36:00 +0100
Subject: [PATCH 19/19] ArmVirt: Allow memory attributes protocol to be
 disabled

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: Gerd Hoffmann <kraxel@redhat.com>
Cc: Oliver Steffen <osteffen@redhat.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Oliver Smith-Denny <osde@linux.microsoft.com>
Cc: Taylor Beebe <taylor.d.beebe@gmail.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Link: https://gitlab.com/qemu-project/qemu/-/issues/1990
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Message-ID: <20231212083600.1889189-1-ardb@google.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 ArmVirtPkg/ArmVirtPkg.dec                     |  6 ++
 .../PlatformBootManagerLib.inf                |  3 +
 .../PlatformBootManagerLib/PlatformBm.c       | 64 +++++++++++++++++++
 3 files changed, 73 insertions(+)

diff --git a/ArmVirtPkg/ArmVirtPkg.dec b/ArmVirtPkg/ArmVirtPkg.dec
index 0f2d7873279f..6fa7ca22b966 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..3a2822cda4b1 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..e9693a1cd9ac 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 +1173,32 @@ 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
+  //
+  Uninstall = FixedPcdGetBool (PcdUninstallMemAttrProtocol);
+  QemuFwCfgParseBool ("opt/org.tianocore/UninstallMemAttrProtocol", &Uninstall);
+  DEBUG ((
+    DEBUG_WARN,
+    "%a: %auninstalling EFI memory protocol\n",
+    __func__,
+    Uninstall ? "" : "not "
+    ));
+  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