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author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2017-02-28 13:45:47 +0000 |
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committer | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2017-03-01 11:43:24 +0000 |
commit | 413edd470932d8e542325fa205b1e4f5e163a85c (patch) | |
tree | 4220acbc9385a9e46fa91cfa58ddb0d4820c1536 /ArmVirtPkg/HighMemDxe | |
parent | e9429e7997b8e668126d71b8030cc3a96c36a652 (diff) | |
download | edk2-413edd470932d8e542325fa205b1e4f5e163a85c.tar.gz edk2-413edd470932d8e542325fa205b1e4f5e163a85c.tar.bz2 edk2-413edd470932d8e542325fa205b1e4f5e163a85c.zip |
ArmVirtPkg/HighMemDxe: preserve non-exec permissions on newly added regions
Using DxeServices::SetMemorySpaceAttributes to set cacheability
attributes has the side effect of stripping permission attributes,
given that those are bits in the same bitfield, and so setting the
Attributes argument to EFI_MEMORY_WB implies not setting EFI_MEMORY_XP
or EFI_MEMORY_RO attributes.
In fact, the situation is even worse, given that the descriptor returned
by DxeServices::GetMemorySpaceDescriptor does not reflect the permission
attributes that may have been set by the preceding call to
DxeServices::AddMemorySpace if PcdDxeNxMemoryProtectionPolicy has been
configured to map EfiConventionalMemory with non-executable permissions.
Note that this applies equally to the non-executable stack and to PE/COFF
sections that may have been mapped with R-X or RW- permissions. This is
due to the ambiguity in the meaning of the EFI_MEMORY_RO/EFI_MEMORY_XP
attributes when used in the GCD memory map, i.e., between signifying
that an underlying RAM region has the controls to be configured as
read-only or non-executable, and signifying that the contents of a
certain UEFI memory region allow them to be mapped with certain
restricted permissions.
So let's check the policy in PcdDxeNxMemoryProtectionPolicy directly,
and set the EFI_MEMORY_XP attribute if appropriate for
EfiConventionalMemory regions.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Diffstat (limited to 'ArmVirtPkg/HighMemDxe')
-rw-r--r-- | ArmVirtPkg/HighMemDxe/HighMemDxe.c | 18 | ||||
-rw-r--r-- | ArmVirtPkg/HighMemDxe/HighMemDxe.inf | 1 |
2 files changed, 17 insertions, 2 deletions
diff --git a/ArmVirtPkg/HighMemDxe/HighMemDxe.c b/ArmVirtPkg/HighMemDxe/HighMemDxe.c index 22f738279b..f70978f641 100644 --- a/ArmVirtPkg/HighMemDxe/HighMemDxe.c +++ b/ArmVirtPkg/HighMemDxe/HighMemDxe.c @@ -37,6 +37,7 @@ InitializeHighMemDxe ( UINTN AddressCells, SizeCells;
UINT64 CurBase;
UINT64 CurSize;
+ UINT64 Attributes;
Status = gBS->LocateProtocol (&gFdtClientProtocolGuid, NULL,
(VOID **)&FdtClient);
@@ -77,8 +78,21 @@ InitializeHighMemDxe ( continue;
}
- Status = gDS->SetMemorySpaceAttributes (CurBase, CurSize,
- EFI_MEMORY_WB);
+ //
+ // Take care not to strip any permission attributes that will have been
+ // set by DxeCore on the region we just added if a strict permission
+ // policy is in effect for EfiConventionalMemory regions.
+ // Unfortunately, we cannot interrogate the GCD memory space map for
+ // those permissions, since they are not recorded there (for historical
+ // reasons), so check the policy directly.
+ //
+ Attributes = EFI_MEMORY_WB;
+ if ((PcdGet64 (PcdDxeNxMemoryProtectionPolicy) &
+ (1U << (UINT32)EfiConventionalMemory)) != 0) {
+ Attributes |= EFI_MEMORY_XP;
+ }
+
+ Status = gDS->SetMemorySpaceAttributes (CurBase, CurSize, Attributes);
if (EFI_ERROR (Status)) {
DEBUG ((EFI_D_ERROR,
diff --git a/ArmVirtPkg/HighMemDxe/HighMemDxe.inf b/ArmVirtPkg/HighMemDxe/HighMemDxe.inf index 3661cfd8c8..89c743ebe0 100644 --- a/ArmVirtPkg/HighMemDxe/HighMemDxe.inf +++ b/ArmVirtPkg/HighMemDxe/HighMemDxe.inf @@ -45,6 +45,7 @@ [Pcd]
gArmTokenSpaceGuid.PcdSystemMemoryBase
+ gEfiMdeModulePkgTokenSpaceGuid.PcdDxeNxMemoryProtectionPolicy
[Depex]
gEfiCpuArchProtocolGuid AND gFdtClientProtocolGuid
|