Re: [PATCH 2/2] MdeModulePkg/Core: Fix feature conflict between NX and Stack guard

["Yao, Jiewen" <jiewen.yao@intel.com>]

Agree.

With this update, reviewed-by: Jiewen.yao@intel.com


> -----Original Message-----
> From: Zeng, Star
> Sent: Tuesday, March 6, 2018 8:16 PM
> To: Wu, Hao A <hao.a.wu@intel.com>; edk2-devel@lists.01.org
> Cc: Wang, Jian J <jian.j.wang@intel.com>; Dong, Eric <eric.dong@intel.com>;
> Yao, Jiewen <jiewen.yao@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>; Zeng, Star
> <star.zeng@intel.com>
> Subject: RE: [PATCH 2/2] MdeModulePkg/Core: Fix feature conflict between NX
> and Stack guard
> 
> A quick minor comment.
> GetHobList() could be used instead of EfiGetSystemConfigurationTable
> (&gEfiHobListGuid, &HobList).
> 
> Thanks,
> Star
> -----Original Message-----
> From: Wu, Hao A
> Sent: Tuesday, March 6, 2018 8:11 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A <hao.a.wu@intel.com>; Wang, Jian J <jian.j.wang@intel.com>;
> Zeng, Star <star.zeng@intel.com>; Dong, Eric <eric.dong@intel.com>; Yao,
> Jiewen <jiewen.yao@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>
> Subject: [PATCH 2/2] MdeModulePkg/Core: Fix feature conflict between NX and
> Stack guard
> 
> If enabled, NX memory protection feature will mark some types of active
> memory as NX (non-executable), which includes the first page of the stack.
> This will overwrite the attributes of the first page of the stack if the stack guard
> feature is also enabled.
> 
> The solution is to override the attributes setting to the first page of the stack by
> adding back the 'EFI_MEMORY_RP' attribute when the stack guard feature is
> enabled.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> ---
>  MdeModulePkg/Core/Dxe/DxeMain.inf             |  4 +-
>  MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c | 61
> +++++++++++++++++++++++++++
>  2 files changed, 64 insertions(+), 1 deletion(-)
> 
> diff --git a/MdeModulePkg/Core/Dxe/DxeMain.inf
> b/MdeModulePkg/Core/Dxe/DxeMain.inf
> index 7334780326..d2e7360ed4 100644
> --- a/MdeModulePkg/Core/Dxe/DxeMain.inf
> +++ b/MdeModulePkg/Core/Dxe/DxeMain.inf
> @@ -3,7 +3,7 @@
>  #
>  #  It provides an implementation of DXE Core that is compliant with DXE CIS.
>  #
> -#  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
> +#  Copyright (c) 2006 - 2018, Intel Corporation. All rights
> +reserved.<BR>
>  #  This program and the accompanying materials  #  are licensed and made
> available under the terms and conditions of the BSD License  #  which
> accompanies this distribution.  The full text of the license may be found at @@
> -130,6 +130,7 @@
>    gEfiPropertiesTableGuid                       ##
> SOMETIMES_PRODUCES   ## SystemTable
>    gEfiMemoryAttributesTableGuid                 ##
> SOMETIMES_PRODUCES   ## SystemTable
>    gEfiEndOfDxeEventGroupGuid                    ##
> SOMETIMES_CONSUMES   ## Event
> +  gEfiHobMemoryAllocStackGuid                   ##
> SOMETIMES_CONSUMES   ## SystemTable
> 
>  [Ppis]
>    gEfiVectorHandoffInfoPpiGuid                  ## UNDEFINED # HOB
> @@ -198,6 +199,7 @@
>    gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPageType
> ## CONSUMES
>    gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPoolType
> ## CONSUMES
>    gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPropertyMask
> ## CONSUMES
> +  gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard
> ## CONSUMES
> 
>  # [Hob]
>  # RESOURCE_DESCRIPTOR   ## CONSUMES
> diff --git a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> index a2ea445eef..a6de22d3af 100644
> --- a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> +++ b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> @@ -801,6 +801,11 @@ InitializeDxeNxMemoryProtectionPolicy (
>    UINT64                            Attributes;
>    LIST_ENTRY                        *Link;
>    EFI_GCD_MAP_ENTRY                 *Entry;
> +  VOID                              *HobList;
> +  EFI_PEI_HOB_POINTERS              Hob;
> +  EFI_HOB_MEMORY_ALLOCATION         *MemoryHob;
> +  EFI_PHYSICAL_ADDRESS              StackBase;
> +  BOOLEAN                           StackBaseFound;
> 
>    //
>    // Get the EFI memory map.
> @@ -832,6 +837,45 @@ InitializeDxeNxMemoryProtectionPolicy (
>    } while (Status == EFI_BUFFER_TOO_SMALL);
>    ASSERT_EFI_ERROR (Status);
> 
> +  StackBase = 0;
> +  StackBaseFound = FALSE;
> +  if (PcdGetBool (PcdCpuStackGuard)) {
> +    //
> +    // Get the base of stack from Hob.
> +    //
> +    Status = EfiGetSystemConfigurationTable (&gEfiHobListGuid, &HobList);
> +    if (!EFI_ERROR (Status)) {
> +      for (Hob.Raw = HobList; !END_OF_HOB_LIST (Hob); Hob.Raw =
> GET_NEXT_HOB (Hob)) {
> +        if (GET_HOB_TYPE(Hob) == EFI_HOB_TYPE_MEMORY_ALLOCATION)
> {
> +          MemoryHob = Hob.MemoryAllocation;
> +          if (CompareGuid(&gEfiHobMemoryAllocStackGuid,
> &MemoryHob->AllocDescriptor.Name)) {
> +            DEBUG ((
> +              DEBUG_INFO,
> +              "%a: StackBase = 0x%016lx  StackSize = 0x%016lx\n",
> +              __FUNCTION__,
> +              MemoryHob->AllocDescriptor.MemoryBaseAddress,
> +              MemoryHob->AllocDescriptor.MemoryLength
> +              ));
> +
> +            StackBase = MemoryHob->AllocDescriptor.MemoryBaseAddress;
> +            //
> +            // Ensure the base of the stack is page-size aligned.
> +            //
> +            ASSERT ((StackBase & EFI_PAGE_MASK) == 0);
> +            StackBaseFound = TRUE;
> +            break;
> +          }
> +        }
> +      }
> +    }
> +
> +    //
> +    // Ensure the base of stack can be found from Hob when stack guard is
> +    // enabled.
> +    //
> +    ASSERT (StackBaseFound);
> +  }
> +
>    DEBUG ((
>      DEBUG_INFO,
>      "%a: applying strict permissions to active memory regions\n", @@ -864,6
> +908,23 @@ InitializeDxeNxMemoryProtectionPolicy (
>            EFI_PAGES_TO_SIZE (1),
>            EFI_MEMORY_RP | Attributes);
>        }
> +
> +      if (StackBaseFound &&
> +          (StackBase >= MemoryMapEntry->PhysicalStart &&
> +           StackBase <  MemoryMapEntry->PhysicalStart +
> +                        LShiftU64 (MemoryMapEntry->NumberOfPages,
> EFI_PAGE_SHIFT)) &&
> +          PcdGetBool (PcdCpuStackGuard)) {
> +
> +        //
> +        // Add EFI_MEMORY_RP attribute for the first page of the stack if
> stack
> +        // guard is enabled.
> +        //
> +        SetUefiImageMemoryAttributes (
> +          StackBase,
> +          EFI_PAGES_TO_SIZE (1),
> +          EFI_MEMORY_RP | Attributes);
> +      }
> +
>      }
>      MemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry,
> DescriptorSize);
>    }
> --
> 2.12.0.windows.1