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ArmVirtPkg/HighMemDxe: use CPU arch protocol to apply memprotect policy

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Instead of invoking gDS->SetMemorySpaceAttributes to set the EFI_MEMORY_XP
attribute on newly added regions, which is guaranteed to fail if the same
attribute was not declared as a capability of the region when it as added,
invoke the CPU arch protocol directly to set the EFI_MEMORY_XP attribute
if our memory protection policy demands it.

Reported-by: Michael Zimmermann <sigmaepsilon92@gmail.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Ard Biesheuvel 2017-03-21 08:47:23 +00:00
parent 09da110819
commit 60bd1e1269
2 changed files with 25 additions and 7 deletions
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31
ArmVirtPkg/HighMemDxe/HighMemDxe.c
View File

@ -20,6 +20,7 @@
#include <Library/PcdLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Protocol/Cpu.h>
#include <Protocol/FdtClient.h>
EFI_STATUS
@ -30,6 +31,7 @@ InitializeHighMemDxe (
)
{
FDT_CLIENT_PROTOCOL *FdtClient;
EFI_CPU_ARCH_PROTOCOL *Cpu;
EFI_STATUS Status, FindNodeStatus;
INT32 Node;
CONST UINT32 *Reg;
@ -43,6 +45,10 @@ InitializeHighMemDxe (
(VOID **)&FdtClient);
ASSERT_EFI_ERROR (Status);
Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL,
(VOID **)&Cpu);
ASSERT_EFI_ERROR (Status);
//
// Check for memory node and add the memory spaces except the lowest one
//
@ -78,13 +84,24 @@ InitializeHighMemDxe (
continue;
}
Status = gDS->SetMemorySpaceAttributes (CurBase, CurSize,
EFI_MEMORY_WB);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_WARN,
"%a: gDS->SetMemorySpaceAttributes() failed on region 0x%lx - 0x%lx (%r)\n",
__FUNCTION__, CurBase, CurBase + CurSize - 1, Status));
}
//
// 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.
// Due to the ambiguous nature of the RO/XP GCD memory space attributes,
// it is impossible to add a memory space with the XP attribute in a way
// that does not result in the XP attribute being set on *all* UEFI
// memory map entries that are carved from it, including code regions
// that require executable permissions.
//
// So instead, we never set the RO/XP attributes in the GCD memory space
// capabilities or attribute fields, and apply any protections directly
// on the page table mappings by going through the cpu arch protocol.
//
Attributes = EFI_MEMORY_WB;
if ((PcdGet64 (PcdDxeNxMemoryProtectionPolicy) &
@ -92,7 +109,7 @@ InitializeHighMemDxe (
Attributes |= EFI_MEMORY_XP;
}
Status = gDS->SetMemorySpaceAttributes (CurBase, CurSize, Attributes);
Status = Cpu->SetMemoryAttributes (Cpu, CurBase, CurSize, Attributes);
if (EFI_ERROR (Status)) {
DEBUG ((EFI_D_ERROR,

1
ArmVirtPkg/HighMemDxe/HighMemDxe.inf
View File

@ -41,6 +41,7 @@
UefiDriverEntryPoint
[Protocols]
gEfiCpuArchProtocolGuid ## CONSUMES
gFdtClientProtocolGuid ## CONSUMES
[Pcd]