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[92.90.16.188]) by smtp.gmail.com with ESMTPSA id k139sm16841848wmg.11.2017.03.21.02.24.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 21 Mar 2017 02:24:38 -0700 (PDT) From: Ard Biesheuvel To: edk2-devel@lists.01.org, lersek@redhat.com Cc: sigmaepsilon92@gmail.com, Ard Biesheuvel Date: Tue, 21 Mar 2017 09:23:28 +0000 Message-Id: <1490088209-8564-2-git-send-email-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1490088209-8564-1-git-send-email-ard.biesheuvel@linaro.org> References: <1490088209-8564-1-git-send-email-ard.biesheuvel@linaro.org> Subject: [PATCH 1/2] ArmVirtPkg/HighMemDxe: use CPU arch protocol to apply memprotect policy X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Mar 2017 09:24:40 -0000 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 --- 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 f70978f6414f..4e41120deff3 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 89c743ebe058..ac1761974f52 100644 --- a/ArmVirtPkg/HighMemDxe/HighMemDxe.inf +++ b/ArmVirtPkg/HighMemDxe/HighMemDxe.inf @@ -41,6 +41,7 @@ [LibraryClasses] UefiDriverEntryPoint [Protocols] + gEfiCpuArchProtocolGuid ## CONSUMES gFdtClientProtocolGuid ## CONSUMES [Pcd] -- 2.7.4