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MdeModulePkg/DxeCore: implement memory protection policy

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This implements a DXE memory protection policy that ensures 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 PcdDxeNxMemoryProtectionPolicy.

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>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
This commit is contained in:
Ard Biesheuvel
2017-02-24 14:51:33 +00:00
parent 973e388af2
commit 7eb927db3e
5 changed files with 409 additions and 1 deletions
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24
MdeModulePkg/Core/Dxe/DxeMain.h
View File

@ -2949,4 +2949,28 @@ MemoryProtectionExitBootServicesCallback (
VOID
);
/**
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()
**/
EFI_STATUS
EFIAPI
ApplyMemoryProtectionPolicy (
IN EFI_MEMORY_TYPE OldType,
IN EFI_MEMORY_TYPE NewType,
IN EFI_PHYSICAL_ADDRESS Memory,
IN UINT64 Length
);
#endif

1
MdeModulePkg/Core/Dxe/DxeMain.inf
View File

@ -191,6 +191,7 @@
gEfiMdeModulePkgTokenSpaceGuid.PcdMemoryProfileDriverPath ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdPropertiesTableEnable ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdImageProtectionPolicy ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdDxeNxMemoryProtectionPolicy ## CONSUMES
# [Hob]
# RESOURCE_DESCRIPTOR ## CONSUMES

7
MdeModulePkg/Core/Dxe/Mem/Page.c
View File

@ -553,6 +553,9 @@ CoreAddMemoryDescriptor (
CoreFreeMemoryMapStack ();
CoreReleaseMemoryLock ();
ApplyMemoryProtectionPolicy (EfiMaxMemoryType, Type, Start,
EFI_PAGES_TO_SIZE (NumberOfPages));
//
// If Loading Module At Fixed Address feature is enabled. try to allocate memory with Runtime code & Boot time code type
//
@ -1344,6 +1347,8 @@ CoreAllocatePages (
NULL
);
InstallMemoryAttributesTableOnMemoryAllocation (MemoryType);
ApplyMemoryProtectionPolicy (EfiConventionalMemory, MemoryType, *Memory,
EFI_PAGES_TO_SIZE (NumberOfPages));
}
return Status;
}
@ -1460,6 +1465,8 @@ CoreFreePages (
NULL
);
InstallMemoryAttributesTableOnMemoryAllocation (MemoryType);
ApplyMemoryProtectionPolicy (MemoryType, EfiConventionalMemory, Memory,
EFI_PAGES_TO_SIZE (NumberOfPages));
}
return Status;
}

7
MdeModulePkg/Core/Dxe/Mem/Pool.c
View File

@ -310,6 +310,10 @@ CoreAllocatePoolPagesI (
Buffer = CoreAllocatePoolPages (PoolType, NoPages, Granularity);
CoreReleaseMemoryLock ();
if (Buffer != NULL) {
ApplyMemoryProtectionPolicy (EfiConventionalMemory, PoolType,
(EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (NoPages));
}
return Buffer;
}
@ -560,6 +564,9 @@ CoreFreePoolPagesI (
CoreAcquireMemoryLock ();
CoreFreePoolPages (Memory, NoPages);
CoreReleaseMemoryLock ();
ApplyMemoryProtectionPolicy (PoolType, EfiConventionalMemory,
(EFI_PHYSICAL_ADDRESS)(UINTN)Memory, EFI_PAGES_TO_SIZE (NoPages));
}
/**

371
MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
View File

@ -64,8 +64,16 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#define DO_NOT_PROTECT 0x00000000
#define PROTECT_IF_ALIGNED_ELSE_ALLOW 0x00000001
#define MEMORY_TYPE_OS_RESERVED_MIN 0x80000000
#define MEMORY_TYPE_OEM_RESERVED_MIN 0x70000000
#define PREVIOUS_MEMORY_DESCRIPTOR(MemoryDescriptor, Size) \
((EFI_MEMORY_DESCRIPTOR *)((UINT8 *)(MemoryDescriptor) - (Size)))
UINT32 mImageProtectionPolicy;
extern LIST_ENTRY mGcdMemorySpaceMap;
/**
Sort code section in image record, based upon CodeSegmentBase from low to high.
@ -646,6 +654,251 @@ UnprotectUefiImage (
}
}
/**
Return the EFI memory permission attribute associated with memory
type 'MemoryType' under the configured DXE memory protection policy.
**/
STATIC
UINT64
GetPermissionAttributeForMemoryType (
IN EFI_MEMORY_TYPE MemoryType
)
{
UINT64 TestBit;
if ((UINT32)MemoryType >= MEMORY_TYPE_OS_RESERVED_MIN) {
TestBit = BIT63;
} else if ((UINT32)MemoryType >= MEMORY_TYPE_OEM_RESERVED_MIN) {
TestBit = BIT62;
} else {
TestBit = LShiftU64 (1, MemoryType);
}
if ((PcdGet64 (PcdDxeNxMemoryProtectionPolicy) & TestBit) != 0) {
return EFI_MEMORY_XP;
} else {
return 0;
}
}
/**
Sort memory map entries based upon PhysicalStart, from low to high.
@param MemoryMap A pointer to the buffer in which firmware places
the current memory map.
@param MemoryMapSize Size, in bytes, of the MemoryMap buffer.
@param DescriptorSize Size, in bytes, of an individual EFI_MEMORY_DESCRIPTOR.
**/
STATIC
VOID
SortMemoryMap (
IN OUT EFI_MEMORY_DESCRIPTOR *MemoryMap,
IN UINTN MemoryMapSize,
IN UINTN DescriptorSize
)
{
EFI_MEMORY_DESCRIPTOR *MemoryMapEntry;
EFI_MEMORY_DESCRIPTOR *NextMemoryMapEntry;
EFI_MEMORY_DESCRIPTOR *MemoryMapEnd;
EFI_MEMORY_DESCRIPTOR TempMemoryMap;
MemoryMapEntry = MemoryMap;
NextMemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize);
MemoryMapEnd = (EFI_MEMORY_DESCRIPTOR *) ((UINT8 *) MemoryMap + MemoryMapSize);
while (MemoryMapEntry < MemoryMapEnd) {
while (NextMemoryMapEntry < MemoryMapEnd) {
if (MemoryMapEntry->PhysicalStart > NextMemoryMapEntry->PhysicalStart) {
CopyMem (&TempMemoryMap, MemoryMapEntry, sizeof(EFI_MEMORY_DESCRIPTOR));
CopyMem (MemoryMapEntry, NextMemoryMapEntry, sizeof(EFI_MEMORY_DESCRIPTOR));
CopyMem (NextMemoryMapEntry, &TempMemoryMap, sizeof(EFI_MEMORY_DESCRIPTOR));
}
NextMemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (NextMemoryMapEntry, DescriptorSize);
}
MemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize);
NextMemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize);
}
}
/**
Merge adjacent memory map entries if they use the same memory protection policy
@param[in, out] MemoryMap A pointer to the buffer in which firmware places
the current memory map.
@param[in, out] MemoryMapSize A pointer to the size, in bytes, of the
MemoryMap buffer. On input, this is the size of
the current memory map. On output,
it is the size of new memory map after merge.
@param[in] DescriptorSize Size, in bytes, of an individual EFI_MEMORY_DESCRIPTOR.
**/
STATIC
VOID
MergeMemoryMapForProtectionPolicy (
IN OUT EFI_MEMORY_DESCRIPTOR *MemoryMap,
IN OUT UINTN *MemoryMapSize,
IN UINTN DescriptorSize
)
{
EFI_MEMORY_DESCRIPTOR *MemoryMapEntry;
EFI_MEMORY_DESCRIPTOR *MemoryMapEnd;
UINT64 MemoryBlockLength;
EFI_MEMORY_DESCRIPTOR *NewMemoryMapEntry;
EFI_MEMORY_DESCRIPTOR *NextMemoryMapEntry;
UINT64 Attributes;
SortMemoryMap (MemoryMap, *MemoryMapSize, DescriptorSize);
MemoryMapEntry = MemoryMap;
NewMemoryMapEntry = MemoryMap;
MemoryMapEnd = (EFI_MEMORY_DESCRIPTOR *) ((UINT8 *) MemoryMap + *MemoryMapSize);
while ((UINTN)MemoryMapEntry < (UINTN)MemoryMapEnd) {
CopyMem (NewMemoryMapEntry, MemoryMapEntry, sizeof(EFI_MEMORY_DESCRIPTOR));
NextMemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize);
do {
MemoryBlockLength = (UINT64) (EFI_PAGES_TO_SIZE((UINTN)MemoryMapEntry->NumberOfPages));
Attributes = GetPermissionAttributeForMemoryType (MemoryMapEntry->Type);
if (((UINTN)NextMemoryMapEntry < (UINTN)MemoryMapEnd) &&
Attributes == GetPermissionAttributeForMemoryType (NextMemoryMapEntry->Type) &&
((MemoryMapEntry->PhysicalStart + MemoryBlockLength) == NextMemoryMapEntry->PhysicalStart)) {
MemoryMapEntry->NumberOfPages += NextMemoryMapEntry->NumberOfPages;
if (NewMemoryMapEntry != MemoryMapEntry) {
NewMemoryMapEntry->NumberOfPages += NextMemoryMapEntry->NumberOfPages;
}
NextMemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (NextMemoryMapEntry, DescriptorSize);
continue;
} else {
MemoryMapEntry = PREVIOUS_MEMORY_DESCRIPTOR (NextMemoryMapEntry, DescriptorSize);
break;
}
} while (TRUE);
MemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize);
NewMemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (NewMemoryMapEntry, DescriptorSize);
}
*MemoryMapSize = (UINTN)NewMemoryMapEntry - (UINTN)MemoryMap;
return ;
}
/**
Remove exec permissions from all regions whose type is identified by
PcdDxeNxMemoryProtectionPolicy
**/
STATIC
VOID
InitializeDxeNxMemoryProtectionPolicy (
VOID
)
{
UINTN MemoryMapSize;
UINTN MapKey;
UINTN DescriptorSize;
UINT32 DescriptorVersion;
EFI_MEMORY_DESCRIPTOR *MemoryMap;
EFI_MEMORY_DESCRIPTOR *MemoryMapEntry;
EFI_MEMORY_DESCRIPTOR *MemoryMapEnd;
EFI_STATUS Status;
UINT64 Attributes;
LIST_ENTRY *Link;
EFI_GCD_MAP_ENTRY *Entry;
//
// 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: applying strict permissions to active memory regions\n",
__FUNCTION__));
MergeMemoryMapForProtectionPolicy (MemoryMap, &MemoryMapSize, DescriptorSize);
MemoryMapEntry = MemoryMap;
MemoryMapEnd = (EFI_MEMORY_DESCRIPTOR *) ((UINT8 *) MemoryMap + MemoryMapSize);
while ((UINTN) MemoryMapEntry < (UINTN) MemoryMapEnd) {
Attributes = GetPermissionAttributeForMemoryType (MemoryMapEntry->Type);
if (Attributes != 0) {
SetUefiImageMemoryAttributes (
MemoryMapEntry->PhysicalStart,
EFI_PAGES_TO_SIZE (MemoryMapEntry->NumberOfPages),
Attributes);
}
MemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize);
}
FreePool (MemoryMap);
//
// Apply the policy for RAM regions that we know are present and
// accessible, but have not been added to the UEFI memory map (yet).
//
if (GetPermissionAttributeForMemoryType (EfiConventionalMemory) != 0) {
DEBUG((DEBUG_ERROR,
"%a: applying strict permissions to inactive memory regions\n",
__FUNCTION__));
CoreAcquireGcdMemoryLock ();
Link = mGcdMemorySpaceMap.ForwardLink;
while (Link != &mGcdMemorySpaceMap) {
Entry = CR (Link, EFI_GCD_MAP_ENTRY, Link, EFI_GCD_MAP_SIGNATURE);
if (Entry->GcdMemoryType == EfiGcdMemoryTypeReserved &&
Entry->EndAddress < MAX_ADDRESS &&
(Entry->Capabilities & (EFI_MEMORY_PRESENT | EFI_MEMORY_INITIALIZED | EFI_MEMORY_TESTED)) ==
(EFI_MEMORY_PRESENT | EFI_MEMORY_INITIALIZED)) {
Attributes = GetPermissionAttributeForMemoryType (EfiConventionalMemory) |
(Entry->Attributes & CACHE_ATTRIBUTE_MASK);
DEBUG ((DEBUG_INFO,
"Untested GCD memory space region: - 0x%016lx - 0x%016lx (0x%016lx)\n",
Entry->BaseAddress, Entry->EndAddress - Entry->BaseAddress + 1,
Attributes));
ASSERT(gCpu != NULL);
gCpu->SetMemoryAttributes (gCpu, Entry->BaseAddress,
Entry->EndAddress - Entry->BaseAddress + 1, Attributes);
}
Link = Link->ForwardLink;
}
CoreReleaseGcdMemoryLock ();
}
}
/**
A notification for CPU_ARCH protocol.
@ -674,6 +927,17 @@ MemoryProtectionCpuArchProtocolNotify (
return;
}
//
// Apply the memory protection policy on non-BScode/RTcode regions.
//
if (PcdGet64 (PcdDxeNxMemoryProtectionPolicy) != 0) {
InitializeDxeNxMemoryProtectionPolicy ();
}
if (mImageProtectionPolicy == 0) {
return;
}
Status = gBS->LocateHandleBuffer (
ByProtocol,
&gEfiLoadedImageProtocolGuid,
@ -753,7 +1017,19 @@ CoreInitializeMemoryProtection (
mImageProtectionPolicy = PcdGet32(PcdImageProtectionPolicy);
if (mImageProtectionPolicy != 0) {
//
// Sanity check the PcdDxeNxMemoryProtectionPolicy setting:
// - code regions should have no EFI_MEMORY_XP attribute
// - EfiConventionalMemory and EfiBootServicesData should use the
// same attribute
//
ASSERT ((GetPermissionAttributeForMemoryType (EfiBootServicesCode) & EFI_MEMORY_XP) == 0);
ASSERT ((GetPermissionAttributeForMemoryType (EfiRuntimeServicesCode) & EFI_MEMORY_XP) == 0);
ASSERT ((GetPermissionAttributeForMemoryType (EfiLoaderCode) & EFI_MEMORY_XP) == 0);
ASSERT (GetPermissionAttributeForMemoryType (EfiBootServicesData) ==
GetPermissionAttributeForMemoryType (EfiConventionalMemory));
if (mImageProtectionPolicy != 0 || PcdGet64 (PcdDxeNxMemoryProtectionPolicy) != 0) {
Status = CoreCreateEvent (
EVT_NOTIFY_SIGNAL,
TPL_CALLBACK,
@ -775,3 +1051,96 @@ CoreInitializeMemoryProtection (
}
return ;
}
/**
Returns whether we are currently executing in SMM mode
**/
STATIC
BOOLEAN
IsInSmm (
VOID
)
{
BOOLEAN InSmm;
InSmm = FALSE;
if (gSmmBase2 != NULL) {
gSmmBase2->InSmm (gSmmBase2, &InSmm);
}
return InSmm;
}
/**
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 we are executing in SMM mode. No permission attributes
are updated in this case
@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()
**/
EFI_STATUS
EFIAPI
ApplyMemoryProtectionPolicy (
IN EFI_MEMORY_TYPE OldType,
IN EFI_MEMORY_TYPE NewType,
IN EFI_PHYSICAL_ADDRESS Memory,
IN UINT64 Length
)
{
UINT64 OldAttributes;
UINT64 NewAttributes;
//
// The policy configured in PcdDxeNxMemoryProtectionPolicy
// does not apply to allocations performed in SMM mode.
//
if (IsInSmm ()) {
return EFI_SUCCESS;
}
//
// 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 (PcdGet64 (PcdDxeNxMemoryProtectionPolicy) == 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, or
// - this is a newly added region (OldType == EfiMaxMemoryType)
//
NewAttributes = GetPermissionAttributeForMemoryType (NewType);
if (OldType != EfiMaxMemoryType) {
OldAttributes = GetPermissionAttributeForMemoryType (OldType);
if (OldAttributes == NewAttributes) {
// policy is the same between OldType and NewType
return EFI_SUCCESS;
}
} else if (NewAttributes == 0) {
// newly added region of a type that does not require protection
return EFI_SUCCESS;
}
return gCpu->SetMemoryAttributes (gCpu, Memory, Length, NewAttributes);
}