From 60bd1e1269ff93390a90014144a835ad71fe2fa0 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 21 Mar 2017 08:47:23 +0000 Subject: [PATCH] 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 Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel Reviewed-by: Laszlo Ersek --- ArmVirtPkg/HighMemDxe/HighMemDxe.c | 31 +++++++++++++++++++++------- ArmVirtPkg/HighMemDxe/HighMemDxe.inf | 1 + 2 files changed, 25 insertions(+), 7 deletions(-) diff --git a/ArmVirtPkg/HighMemDxe/HighMemDxe.c b/ArmVirtPkg/HighMemDxe/HighMemDxe.c index f70978f641..4e41120def 100644 --- a/ArmVirtPkg/HighMemDxe/HighMemDxe.c +++ b/ArmVirtPkg/HighMemDxe/HighMemDxe.c @@ -20,6 +20,7 @@ #include #include +#include #include 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)); + } + + // + // 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. // - // 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. + // 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, diff --git a/ArmVirtPkg/HighMemDxe/HighMemDxe.inf b/ArmVirtPkg/HighMemDxe/HighMemDxe.inf index 89c743ebe0..ac1761974f 100644 --- a/ArmVirtPkg/HighMemDxe/HighMemDxe.inf +++ b/ArmVirtPkg/HighMemDxe/HighMemDxe.inf @@ -41,6 +41,7 @@ UefiDriverEntryPoint [Protocols] + gEfiCpuArchProtocolGuid ## CONSUMES gFdtClientProtocolGuid ## CONSUMES [Pcd] -- 2.39.2