On 20 July 2018 at 21:38, Sughosh Ganu <[email protected]> wrote:
> From: Achin Gupta <[email protected]>
>
> The Standalone MM drivers runs in S-EL0 in AArch64 on ARM Standard
> Platforms and is deployed during SEC phase. The memory allocated to
> the Standalone MM drivers should be marked as RO+X.
>
> During PE/COFF Image section parsing, this patch implements extra
> action "UpdatePeCoffPermissions" to request the privileged firmware in
> EL3 to update the permissions.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Sughosh Ganu <[email protected]>
Apologies for bringing this up only now, but I don't think I was ever
cc'ed on these patches.
We are relying on a debug hook in the PE/COFF loader to ensure that we
don't end up with memory that is both writable and executable in the
secure world. Do we really think that is a good idea?
(I know this code was derived from a proof of concept that I did years
ago, but that was just a PoC)
> ---
> ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.inf | 7
> +
> ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.c | 171
> +++++++++++++++++++-
> 2 files changed, 176 insertions(+), 2 deletions(-)
>
> diff --git
> a/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.inf
> b/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.inf
> index c1f717e5bda1..38bf3993ae99 100644
> --- a/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.inf
> +++ b/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.inf
> @@ -33,7 +33,14 @@ [Sources.common]
> DebugPeCoffExtraActionLib.c
>
> [Packages]
> + ArmPkg/ArmPkg.dec
> MdePkg/MdePkg.dec
> + StandaloneMmPkg/StandaloneMmPkg.dec
> +
> +[FeaturePcd]
> + gStandaloneMmPkgTokenSpaceGuid.PcdStandaloneMmEnable
>
> [LibraryClasses]
> + ArmMmuLib
> DebugLib
> + PcdLib
> diff --git
> a/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.c
> b/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.c
> index f298e58cdfca..8e621de4a87a 100644
> --- a/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.c
> +++ b/ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.c
> @@ -15,14 +15,165 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND,
> EITHER EXPRESS OR IMPLIED.
> **/
>
> #include <PiDxe.h>
> -#include <Library/PeCoffLib.h>
>
> +#include <Library/ArmMmuLib.h>
> #include <Library/BaseLib.h>
> -#include <Library/DebugLib.h>
> #include <Library/BaseMemoryLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/PcdLib.h>
> +#include <Library/PeCoffLib.h>
> #include <Library/PeCoffExtraActionLib.h>
> #include <Library/PrintLib.h>
>
> +typedef RETURN_STATUS (*REGION_PERMISSION_UPDATE_FUNC) (
> + IN EFI_PHYSICAL_ADDRESS BaseAddress,
> + IN UINT64 Length
> + );
> +
> +STATIC
> +RETURN_STATUS
> +UpdatePeCoffPermissions (
> + IN CONST PE_COFF_LOADER_IMAGE_CONTEXT *ImageContext,
> + IN REGION_PERMISSION_UPDATE_FUNC NoExecUpdater,
> + IN REGION_PERMISSION_UPDATE_FUNC ReadOnlyUpdater
> + )
> +{
> + RETURN_STATUS Status;
> + EFI_IMAGE_OPTIONAL_HEADER_PTR_UNION Hdr;
> + EFI_IMAGE_OPTIONAL_HEADER_UNION HdrData;
> + UINTN Size;
> + UINTN ReadSize;
> + UINT32 SectionHeaderOffset;
> + UINTN NumberOfSections;
> + UINTN Index;
> + EFI_IMAGE_SECTION_HEADER SectionHeader;
> + PE_COFF_LOADER_IMAGE_CONTEXT TmpContext;
> + EFI_PHYSICAL_ADDRESS Base;
> +
> + //
> + // We need to copy ImageContext since PeCoffLoaderGetImageInfo ()
> + // will mangle the ImageAddress field
> + //
> + CopyMem (&TmpContext, ImageContext, sizeof (TmpContext));
> +
> + if (TmpContext.PeCoffHeaderOffset == 0) {
> + Status = PeCoffLoaderGetImageInfo (&TmpContext);
> + if (RETURN_ERROR (Status)) {
> + DEBUG ((DEBUG_ERROR,
> + "%a: PeCoffLoaderGetImageInfo () failed (Status = %r)\n",
> + __FUNCTION__, Status));
> + return Status;
> + }
> + }
> +
> + if (TmpContext.IsTeImage &&
> + TmpContext.ImageAddress == ImageContext->ImageAddress) {
> + DEBUG ((DEBUG_INFO, "%a: ignoring XIP TE image at 0x%lx\n", __FUNCTION__,
> + ImageContext->ImageAddress));
> + return RETURN_SUCCESS;
> + }
> +
> + if (TmpContext.SectionAlignment < EFI_PAGE_SIZE) {
> + //
> + // The sections need to be at least 4 KB aligned, since that is the
> + // granularity at which we can tighten permissions. So just clear the
> + // noexec permissions on the entire region.
> + //
> + if (!TmpContext.IsTeImage) {
> + DEBUG ((DEBUG_WARN,
> + "%a: non-TE Image at 0x%lx has SectionAlignment < 4 KB (%lu)\n",
> + __FUNCTION__, ImageContext->ImageAddress,
> TmpContext.SectionAlignment));
> + }
> + Base = ImageContext->ImageAddress & ~(EFI_PAGE_SIZE - 1);
> + Size = ImageContext->ImageAddress - Base + ImageContext->ImageSize;
> + return NoExecUpdater (Base, ALIGN_VALUE (Size, EFI_PAGE_SIZE));
> + }
> +
> + //
> + // Read the PE/COFF Header. For PE32 (32-bit) this will read in too much
> + // data, but that should not hurt anything. Hdr.Pe32->OptionalHeader.Magic
> + // determines if this is a PE32 or PE32+ image. The magic is in the same
> + // location in both images.
> + //
> + Hdr.Union = &HdrData;
> + Size = sizeof (EFI_IMAGE_OPTIONAL_HEADER_UNION);
> + ReadSize = Size;
> + Status = TmpContext.ImageRead (TmpContext.Handle,
> + TmpContext.PeCoffHeaderOffset, &Size, Hdr.Pe32);
> + if (RETURN_ERROR (Status) || (Size != ReadSize)) {
> + DEBUG ((DEBUG_ERROR,
> + "%a: TmpContext.ImageRead () failed (Status = %r)\n",
> + __FUNCTION__, Status));
> + return Status;
> + }
> +
> + ASSERT (Hdr.Pe32->Signature == EFI_IMAGE_NT_SIGNATURE);
> +
> + SectionHeaderOffset = TmpContext.PeCoffHeaderOffset + sizeof (UINT32) +
> + sizeof (EFI_IMAGE_FILE_HEADER);
> + NumberOfSections = (UINTN)(Hdr.Pe32->FileHeader.NumberOfSections);
> +
> + switch (Hdr.Pe32->OptionalHeader.Magic) {
> + case EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC:
> + SectionHeaderOffset += Hdr.Pe32->FileHeader.SizeOfOptionalHeader;
> + break;
> + case EFI_IMAGE_NT_OPTIONAL_HDR64_MAGIC:
> + SectionHeaderOffset += Hdr.Pe32Plus->FileHeader.SizeOfOptionalHeader;
> + break;
> + default:
> + ASSERT (FALSE);
> + }
> +
> + //
> + // Iterate over the sections
> + //
> + for (Index = 0; Index < NumberOfSections; Index++) {
> + //
> + // Read section header from file
> + //
> + Size = sizeof (EFI_IMAGE_SECTION_HEADER);
> + ReadSize = Size;
> + Status = TmpContext.ImageRead (TmpContext.Handle, SectionHeaderOffset,
> + &Size, &SectionHeader);
> + if (RETURN_ERROR (Status) || (Size != ReadSize)) {
> + DEBUG ((DEBUG_ERROR,
> + "%a: TmpContext.ImageRead () failed (Status = %r)\n",
> + __FUNCTION__, Status));
> + return Status;
> + }
> +
> + Base = TmpContext.ImageAddress + SectionHeader.VirtualAddress;
> +
> + if ((SectionHeader.Characteristics & EFI_IMAGE_SCN_MEM_EXECUTE) == 0) {
> +
> + if ((SectionHeader.Characteristics & EFI_IMAGE_SCN_MEM_WRITE) == 0 &&
> + TmpContext.ImageType != EFI_IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER) {
> +
> + DEBUG ((DEBUG_INFO,
> + "%a: Mapping section %d of image at 0x%lx with RO-XN permissions
> and size 0x%x\n",
> + __FUNCTION__, Index, Base, SectionHeader.Misc.VirtualSize));
> + ReadOnlyUpdater (Base, SectionHeader.Misc.VirtualSize);
> + } else {
> + DEBUG ((DEBUG_WARN,
> + "%a: Mapping section %d of image at 0x%lx with RW-XN permissions
> and size 0x%x\n",
> + __FUNCTION__, Index, Base, SectionHeader.Misc.VirtualSize));
> + }
> + } else {
> + DEBUG ((DEBUG_INFO,
> + "%a: Mapping section %d of image at 0x%lx with RO-XN permissions
> and size 0x%x\n",
> + __FUNCTION__, Index, Base, SectionHeader.Misc.VirtualSize));
> + ReadOnlyUpdater (Base, SectionHeader.Misc.VirtualSize);
> +
> + DEBUG ((DEBUG_INFO,
> + "%a: Mapping section %d of image at 0x%lx with RO-X permissions
> and size 0x%x\n",
> + __FUNCTION__, Index, Base, SectionHeader.Misc.VirtualSize));
> + NoExecUpdater (Base, SectionHeader.Misc.VirtualSize);
> + }
> +
> + SectionHeaderOffset += sizeof (EFI_IMAGE_SECTION_HEADER);
> + }
> + return RETURN_SUCCESS;
> +}
>
> /**
> If the build is done on cygwin the paths are cygpaths.
> @@ -83,6 +234,14 @@ PeCoffLoaderRelocateImageExtraAction (
> CHAR8 Temp[512];
> #endif
>
> + if (PcdGetBool(PcdStandaloneMmEnable) == TRUE) {
> + UpdatePeCoffPermissions (
> + ImageContext,
> + ArmClearMemoryRegionNoExec,
> + ArmSetMemoryRegionReadOnly
> + );
> + }
> +
> if (ImageContext->PdbPointer) {
> #ifdef __CC_ARM
> #if (__ARMCC_VERSION < 500000)
> @@ -125,6 +284,14 @@ PeCoffLoaderUnloadImageExtraAction (
> CHAR8 Temp[512];
> #endif
>
> + if (PcdGetBool(PcdStandaloneMmEnable) == TRUE) {
> + UpdatePeCoffPermissions (
> + ImageContext,
> + ArmSetMemoryRegionNoExec,
> + ArmClearMemoryRegionReadOnly
> + );
> + }
> +
> if (ImageContext->PdbPointer) {
> #ifdef __CC_ARM
> // Print out the command for the RVD debugger to load symbols for this
> image
> --
> 2.7.4
>
> _______________________________________________
> edk2-devel mailing list
> [email protected]
> https://lists.01.org/mailman/listinfo/edk2-devel
_______________________________________________
edk2-devel mailing list
[email protected]
https://lists.01.org/mailman/listinfo/edk2-devel
