mirror of https://github.com/acidanthera/audk.git
ArmVirtPkg/HighMemDxe: use CPU arch protocol to apply memprotect policy
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>
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@ -20,6 +20,7 @@
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#include <Library/PcdLib.h>
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#include <Library/UefiBootServicesTableLib.h>
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#include <Protocol/Cpu.h>
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#include <Protocol/FdtClient.h>
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EFI_STATUS
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@ -30,6 +31,7 @@ InitializeHighMemDxe (
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)
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{
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FDT_CLIENT_PROTOCOL *FdtClient;
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EFI_CPU_ARCH_PROTOCOL *Cpu;
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EFI_STATUS Status, FindNodeStatus;
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INT32 Node;
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CONST UINT32 *Reg;
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@ -43,6 +45,10 @@ InitializeHighMemDxe (
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(VOID **)&FdtClient);
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ASSERT_EFI_ERROR (Status);
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Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL,
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(VOID **)&Cpu);
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ASSERT_EFI_ERROR (Status);
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//
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// Check for memory node and add the memory spaces except the lowest one
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//
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@ -78,13 +84,24 @@ InitializeHighMemDxe (
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continue;
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}
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Status = gDS->SetMemorySpaceAttributes (CurBase, CurSize,
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EFI_MEMORY_WB);
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if (EFI_ERROR (Status)) {
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DEBUG ((DEBUG_WARN,
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"%a: gDS->SetMemorySpaceAttributes() failed on region 0x%lx - 0x%lx (%r)\n",
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__FUNCTION__, CurBase, CurBase + CurSize - 1, Status));
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}
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//
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// Take care not to strip any permission attributes that will have been
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// set by DxeCore on the region we just added if a strict permission
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// policy is in effect for EfiConventionalMemory regions.
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// Unfortunately, we cannot interrogate the GCD memory space map for
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// those permissions, since they are not recorded there (for historical
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// reasons), so check the policy directly.
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// Due to the ambiguous nature of the RO/XP GCD memory space attributes,
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// it is impossible to add a memory space with the XP attribute in a way
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// that does not result in the XP attribute being set on *all* UEFI
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// memory map entries that are carved from it, including code regions
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// that require executable permissions.
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//
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// So instead, we never set the RO/XP attributes in the GCD memory space
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// capabilities or attribute fields, and apply any protections directly
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// on the page table mappings by going through the cpu arch protocol.
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//
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Attributes = EFI_MEMORY_WB;
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if ((PcdGet64 (PcdDxeNxMemoryProtectionPolicy) &
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@ -92,7 +109,7 @@ InitializeHighMemDxe (
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Attributes |= EFI_MEMORY_XP;
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}
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Status = gDS->SetMemorySpaceAttributes (CurBase, CurSize, Attributes);
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Status = Cpu->SetMemoryAttributes (Cpu, CurBase, CurSize, Attributes);
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if (EFI_ERROR (Status)) {
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DEBUG ((EFI_D_ERROR,
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@ -41,6 +41,7 @@
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UefiDriverEntryPoint
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[Protocols]
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gEfiCpuArchProtocolGuid ## CONSUMES
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gFdtClientProtocolGuid ## CONSUMES
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[Pcd]
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