MdeModulePkg: Variable: Re-prioritize TCG/TCG2 protocol

[mirror_edk2.git] / MdeModulePkg / Universal / Variable / RuntimeDxe / TcgMorLockSmm.c

diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
index faeaabb224afc6fa9214fdc34191e94fce2ee864..28aa2893c6f864bfbeffa162422ef2bba3ae1b65 100644 (file)
--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
@@ -4,7 +4,7 @@
   This module initilizes MemoryOverwriteRequestControlLock variable.\r
   This module adds Variable Hook and check MemoryOverwriteRequestControlLock.\r
 \r
-Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>\r
+Copyright (c) 2016 - 2018, Intel Corporation. All rights reserved.<BR>\r
 This program and the accompanying materials\r
 are licensed and made available under the terms and conditions of the BSD License\r
 which accompanies this distribution.  The full text of the license may be found at\r
@@ -21,6 +21,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include <Library/DebugLib.h>\r
 #include <Library/BaseLib.h>\r
 #include <Library/BaseMemoryLib.h>\r
+#include <Library/UefiBootServicesTableLib.h>\r
 #include "Variable.h"\r
 \r
 typedef struct {\r
@@ -33,6 +34,8 @@ VARIABLE_TYPE  mMorVariableType[] = {
   {MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME,  &gEfiMemoryOverwriteRequestControlLockGuid},\r
 };\r
 \r
+BOOLEAN         mMorPassThru = FALSE;\r
+\r
 #define MOR_LOCK_DATA_UNLOCKED           0x0\r
 #define MOR_LOCK_DATA_LOCKED_WITHOUT_KEY 0x1\r
 #define MOR_LOCK_DATA_LOCKED_WITH_KEY    0x2\r
@@ -113,7 +116,7 @@ IsMorLockVariable (
   @retval  EFI_DEVICE_ERROR       The variable could not be saved due to a hardware failure.\r
   @retval  EFI_WRITE_PROTECTED    The variable in question is read-only.\r
   @retval  EFI_WRITE_PROTECTED    The variable in question cannot be deleted.\r
-  @retval  EFI_SECURITY_VIOLATION The variable could not be written due to EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\r
+  @retval  EFI_SECURITY_VIOLATION The variable could not be written due to EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\r
                                   set but the AuthInfo does NOT pass the validation check carried\r
                                   out by the firmware.\r
   @retval  EFI_NOT_FOUND          The variable trying to be updated or deleted was not found.\r
@@ -362,6 +365,13 @@ SetVariableCheckHandlerMor (
   // Mor Variable\r
   //\r
 \r
+  //\r
+  // Permit deletion for passthru request.\r
+  //\r
+  if (((Attributes == 0) || (DataSize == 0)) && mMorPassThru) {\r
+    return EFI_SUCCESS;\r
+  }\r
+\r
   //\r
   // Basic Check\r
   //\r
@@ -409,6 +419,8 @@ MorLockInitAtEndOfDxe (
 {\r
   UINTN      MorSize;\r
   EFI_STATUS MorStatus;\r
+  EFI_STATUS TcgStatus;\r
+  VOID       *TcgInterface;\r
 \r
   if (!mMorLockInitializationRequired) {\r
     //\r
@@ -437,17 +449,72 @@ MorLockInitAtEndOfDxe (
 \r
   if (MorStatus == EFI_BUFFER_TOO_SMALL) {\r
     //\r
-    // The MOR variable exists; set the MOR Control Lock variable to report the\r
-    // capability to the OS.\r
+    // The MOR variable exists.\r
     //\r
-    SetMorLockVariable (0);\r
-    return;\r
+    // Some OSes don't follow the TCG's Platform Reset Attack Mitigation spec\r
+    // in that the OS should never create the MOR variable, only read and write\r
+    // it -- these OSes (unintentionally) create MOR if the platform firmware\r
+    // does not produce it. Whether this is the case (from the last OS boot)\r
+    // can be deduced from the absence of the TCG / TCG2 protocols, as edk2's\r
+    // MOR implementation depends on (one of) those protocols.\r
+    //\r
+    TcgStatus = gBS->LocateProtocol (\r
+                       &gEfiTcg2ProtocolGuid,\r
+                       NULL,                     // Registration\r
+                       &TcgInterface\r
+                       );\r
+    if (EFI_ERROR (TcgStatus)) {\r
+      TcgStatus = gBS->LocateProtocol (\r
+                         &gEfiTcgProtocolGuid,\r
+                         NULL,                   // Registration\r
+                         &TcgInterface\r
+                         );\r
+    }\r
+\r
+    if (!EFI_ERROR (TcgStatus)) {\r
+      //\r
+      // The MOR variable originates from the platform firmware; set the MOR\r
+      // Control Lock variable to report the locking capability to the OS.\r
+      //\r
+      SetMorLockVariable (0);\r
+      return;\r
+    }\r
+\r
+    //\r
+    // The MOR variable's origin is inexplicable; delete it.\r
+    //\r
+    DEBUG ((\r
+      DEBUG_WARN,\r
+      "%a: deleting unexpected / unsupported variable %g:%s\n",\r
+      __FUNCTION__,\r
+      &gEfiMemoryOverwriteControlDataGuid,\r
+      MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME\r
+      ));\r
+\r
+    mMorPassThru = TRUE;\r
+    VariableServiceSetVariable (\r
+      MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,\r
+      &gEfiMemoryOverwriteControlDataGuid,\r
+      0,                                      // Attributes\r
+      0,                                      // DataSize\r
+      NULL                                    // Data\r
+      );\r
+    mMorPassThru = FALSE;\r
   }\r
 \r
   //\r
-  // The platform does not support the MOR variable. Delete the MOR Control\r
-  // Lock variable (should it exists for some reason) and prevent other modules\r
-  // from creating it.\r
+  // The MOR variable is absent; the platform firmware does not support it.\r
+  // Lock the variable so that no other module may create it.\r
+  //\r
+  VariableLockRequestToLock (\r
+    NULL,                                   // This\r
+    MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,\r
+    &gEfiMemoryOverwriteControlDataGuid\r
+    );\r
+\r
+  //\r
+  // Delete the MOR Control Lock variable too (should it exists for some\r
+  // reason) and prevent other modules from creating it.\r
   //\r
   mMorLockPassThru = TRUE;\r
   VariableServiceSetVariable (\r