@@ -191,6 +191,7 @@ [Pcd]
gEfiMdeModulePkgTokenSpaceGuid.PcdMemoryProfileDriverPath ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdPropertiesTableEnable ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdImageProtectionPolicy ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdDxeMemoryProtectionPolicy ## CONSUMES
# [Hob]
# RESOURCE_DESCRIPTOR ## CONSUMES
@@ -1305,6 +1305,101 @@ Done:
}
/**
+ Return the EFI memory permission attribute associated with memory type 'Type'
+ under the configured DXE memory protection policy.
+**/
+STATIC
+UINT64
+EFIAPI
+GetPermissionAttributeForMemoryType (
+ IN EFI_MEMORY_TYPE Type
+ )
+{
+ switch (Type) {
+ case EfiBootServicesCode:
+ case EfiRuntimeServicesCode:
+ case EfiLoaderCode:
+ break;
+
+ default:
+ if ((PcdGet32 (PcdDxeMemoryProtectionPolicy) & BIT0) != 0) {
+ return EFI_MEMORY_XP;
+ }
+ break;
+ case EfiReservedMemoryType:
+ if ((PcdGet32 (PcdDxeMemoryProtectionPolicy) & BIT1) != 0) {
+ return EFI_MEMORY_XP;
+ }
+ break;
+ case EfiACPIMemoryNVS:
+ if ((PcdGet32 (PcdDxeMemoryProtectionPolicy) & BIT2) != 0) {
+ return EFI_MEMORY_XP;
+ }
+ break;
+ }
+ return 0;
+}
+
+/**
+ Manage memory permission attributes on a memory range, according to the
+ configured DXE memory protection policy.
+
+ @param OldType The old memory type of the range
+ @param NewType The new memory type of the range
+ @param Memory The base address of the range
+ @param Length The size of the range (in bytes)
+
+ @return EFI_SUCCESS If the the CPU arch protocol is not installed yet
+ @return EFI_SUCCESS If no DXE memory protection policy has been configured
+ @return EFI_SUCCESS If OldType and NewType use the same permission attributes
+ @return other Return value of gCpu->SetMemoryAttributes()
+
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+ApplyMemoryProtection (
+ IN EFI_MEMORY_TYPE OldType,
+ IN EFI_MEMORY_TYPE NewType,
+ IN EFI_PHYSICAL_ADDRESS Memory,
+ IN UINT64 Length
+ )
+{
+ UINT64 OldAttributes;
+ UINT64 NewAttributes;
+
+ //
+ // If the CPU arch protocol is not installed yet, we cannot manage memory
+ // permission attributes, and it is the job of the driver that installs this
+ // protocol to set the permissions on existing allocations.
+ //
+ if (gCpu == NULL) {
+ return EFI_SUCCESS;
+ }
+
+ //
+ // Check if a DXE memory protection policy has been configured
+ //
+ if (PcdGet32 (PcdDxeMemoryProtectionPolicy) == 0) {
+ return EFI_SUCCESS;
+ }
+
+ //
+ // Update the executable permissions according to the DXE memory
+ // protection policy, but only if the policy is different between
+ // the old and the new type.
+ //
+ OldAttributes = GetPermissionAttributeForMemoryType (OldType);
+ NewAttributes = GetPermissionAttributeForMemoryType (NewType);
+
+ if (OldAttributes == NewAttributes) {
+ return EFI_SUCCESS;
+ }
+
+ return gCpu->SetMemoryAttributes (gCpu, Memory, Length, NewAttributes);
+}
+
+/**
Allocates pages from the memory map.
@param Type The type of allocation to perform
@@ -1344,6 +1439,8 @@ CoreAllocatePages (
NULL
);
InstallMemoryAttributesTableOnMemoryAllocation (MemoryType);
+ ApplyMemoryProtection (EfiConventionalMemory, MemoryType, *Memory,
+ EFI_PAGES_TO_SIZE (NumberOfPages));
}
return Status;
}
@@ -1460,6 +1557,8 @@ CoreFreePages (
NULL
);
InstallMemoryAttributesTableOnMemoryAllocation (MemoryType);
+ ApplyMemoryProtection (MemoryType, EfiConventionalMemory, Memory,
+ EFI_PAGES_TO_SIZE (NumberOfPages));
}
return Status;
}
@@ -1856,6 +1955,9 @@ CoreAllocatePoolPages (
DEBUG ((DEBUG_ERROR | DEBUG_PAGE, "AllocatePoolPages: failed to allocate %d pages\n", (UINT32)NumberOfPages));
} else {
CoreConvertPages (Start, NumberOfPages, PoolType);
+
+ ApplyMemoryProtection (EfiConventionalMemory, PoolType, Start,
+ EFI_PAGES_TO_SIZE (NumberOfPages));
}
return (VOID *)(UINTN) Start;
@@ -1877,6 +1979,9 @@ CoreFreePoolPages (
)
{
CoreConvertPages (Memory, NumberOfPages, EfiConventionalMemory);
+
+ ApplyMemoryProtection (PoolType, EfiConventionalMemory, Memory,
+ EFI_PAGES_TO_SIZE (NumberOfPages));
}
@@ -639,6 +639,97 @@ UnprotectUefiImage (
}
/**
+ Remove exec permissions from all regions whose type is identified by
+ PcdDxeMemoryProtectionPolicy
+**/
+STATIC
+VOID
+ApplyDxeMemoryProtectionPolicy (
+ VOID
+ )
+{
+ UINTN MemoryMapSize;
+ UINTN MapKey;
+ UINTN DescriptorSize;
+ UINT32 DescriptorVersion;
+ EFI_MEMORY_DESCRIPTOR *MemoryMap;
+ EFI_MEMORY_DESCRIPTOR *MemoryMapEntry;
+ EFI_MEMORY_DESCRIPTOR *MemoryMapEnd;
+ EFI_STATUS Status;
+
+ //
+ // Get the EFI memory map.
+ //
+ MemoryMapSize = 0;
+ MemoryMap = NULL;
+
+ Status = gBS->GetMemoryMap (
+ &MemoryMapSize,
+ MemoryMap,
+ &MapKey,
+ &DescriptorSize,
+ &DescriptorVersion
+ );
+ ASSERT (Status == EFI_BUFFER_TOO_SMALL);
+ do {
+ MemoryMap = (EFI_MEMORY_DESCRIPTOR *) AllocatePool (MemoryMapSize);
+ ASSERT (MemoryMap != NULL);
+ Status = gBS->GetMemoryMap (
+ &MemoryMapSize,
+ MemoryMap,
+ &MapKey,
+ &DescriptorSize,
+ &DescriptorVersion
+ );
+ if (EFI_ERROR (Status)) {
+ FreePool (MemoryMap);
+ }
+ } while (Status == EFI_BUFFER_TOO_SMALL);
+ ASSERT_EFI_ERROR (Status);
+
+ DEBUG((DEBUG_ERROR, "%a: removing exec permissions from memory regions\n",
+ __FUNCTION__));
+
+ for (MemoryMapEntry = MemoryMap,
+ MemoryMapEnd = (EFI_MEMORY_DESCRIPTOR *) ((UINT8 *) MemoryMap + MemoryMapSize);
+ (UINTN) MemoryMapEntry < (UINTN) MemoryMapEnd;
+ MemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize)) {
+
+ switch (MemoryMapEntry->Type) {
+ case EfiBootServicesCode:
+ case EfiRuntimeServicesCode:
+ case EfiLoaderCode:
+ continue;
+
+ default:
+ if ((PcdGet32 (PcdDxeMemoryProtectionPolicy) & BIT0) == 0) {
+ continue;
+ }
+ break;
+
+ case EfiReservedMemoryType:
+ if ((PcdGet32 (PcdDxeMemoryProtectionPolicy) & BIT1) == 0) {
+ continue;
+ }
+ break;
+
+ case EfiACPIMemoryNVS:
+ if ((PcdGet32 (PcdDxeMemoryProtectionPolicy) & BIT2) == 0) {
+ continue;
+ }
+ break;
+ }
+
+ SetUefiImageMemoryAttributes (
+ MemoryMapEntry->PhysicalStart,
+ EFI_PAGES_TO_SIZE (MemoryMapEntry->NumberOfPages),
+ EFI_MEMORY_XP);
+ }
+ FreePool (MemoryMap);
+}
+
+
+/**
A notification for CPU_ARCH protocol.
@param[in] Event Event whose notification function is being invoked.
@@ -666,6 +757,17 @@ MemoryProtectionCpuArchProtocolNotify (
return;
}
+ //
+ // Apply the memory protection policy on non-BScode/RTcode regions.
+ //
+ if (PcdGet32 (PcdDxeMemoryProtectionPolicy) != 0) {
+ ApplyDxeMemoryProtectionPolicy ();
+ }
+
+ if (mImageProtectionPolicy == 0) {
+ return;
+ }
+
Status = gBS->LocateHandleBuffer (
ByProtocol,
&gEfiLoadedImageProtocolGuid,
@@ -745,7 +847,7 @@ CoreInitializeMemoryProtection (
mImageProtectionPolicy = PcdGet32(PcdImageProtectionPolicy);
- if (mImageProtectionPolicy != 0) {
+ if (mImageProtectionPolicy != 0 || PcdGet32 (PcdDxeMemoryProtectionPolicy) != 0) {
Status = CoreCreateEvent (
EVT_NOTIFY_SIGNAL,
TPL_CALLBACK,
This implements a DXE memory protection policy that ensure that regions that don't require executable permissions are mapped with the non-exec attribute set. First of all, it iterates over all entries in the UEFI memory map, and removes executable permissions according to the configured DXE memory protection policy, as recorded in PcdDxeMemoryProtectionPolicy. Secondly, it sets or clears the non-executable attribute when allocating or freeing pages, both for page based or pool based allocations. Note that this complements the image protection facility, which applies strict permissions to BootServicesCode/RuntimeServicesCode regions when the section alignment allows it. The memory protection configured by this patch operates on non-code regions only. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- MdeModulePkg/Core/Dxe/DxeMain.inf | 1 + MdeModulePkg/Core/Dxe/Mem/Page.c | 105 ++++++++++++++++++++ MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c | 104 ++++++++++++++++++- 3 files changed, 209 insertions(+), 1 deletion(-) -- 2.7.4 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel