SecurityPkg Variable: Allow the delete operation of common auth variable at user physical presence.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17042 6f19259b-4bc3-4df7-8a09-765794883524

SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.c

@@ -19,7 +19,7 @@
   They will do basic validation for authentication data structure, then call crypto library
   to verify the signature.
 
-Copyright (c) 2009 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2009 - 2015, 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
@@ -129,36 +129,6 @@ InCustomMode (
   return FALSE;
 }
 
-
-/**
-  Internal function to delete a Variable given its name and GUID, no authentication
-  required.
-
-  @param[in]      VariableName            Name of the Variable.
-  @param[in]      VendorGuid              GUID of the Variable.
-
-  @retval EFI_SUCCESS              Variable deleted successfully.
-  @retval Others                   The driver failded to start the device.
-
-**/
-EFI_STATUS
-DeleteVariable (
-  IN  CHAR16                    *VariableName,
-  IN  EFI_GUID                  *VendorGuid
-  )
-{
-  EFI_STATUS              Status;
-  VARIABLE_POINTER_TRACK  Variable;
-
-  Status = FindVariable (VariableName, VendorGuid, &Variable, &mVariableModuleGlobal->VariableGlobal, FALSE);
-  if (EFI_ERROR (Status)) {
-    return EFI_SUCCESS;
-  }
-
-  ASSERT (Variable.CurrPtr != NULL);
-  return UpdateVariable (VariableName, VendorGuid, NULL, 0, 0, 0, 0, &Variable, NULL);
-}
-
 /**
   Initializes for authenticated varibale service.
 
@@ -1281,6 +1251,59 @@ ProcessVarWithKek (
   return Status;
 }
 
+/**
+  Check if it is to delete auth variable.
+
+  @param[in] Data               Data pointer.
+  @param[in] DataSize           Size of Data.
+  @param[in] Variable           The variable information which is used to keep track of variable usage.
+  @param[in] Attributes         Attribute value of the variable.
+
+  @retval TRUE                  It is to delete auth variable.
+  @retval FALSE                 It is not to delete auth variable.
+
+**/
+BOOLEAN
+IsDeleteAuthVariable (
+  IN  VOID                      *Data,
+  IN  UINTN                     DataSize,
+  IN  VARIABLE_POINTER_TRACK    *Variable,
+  IN  UINT32                    Attributes
+  )
+{
+  BOOLEAN                       Del;
+  UINT8                         *Payload;
+  UINTN                         PayloadSize;
+
+  Del = FALSE;
+
+  //
+  // To delete a variable created with the EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS
+  // or the EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS attribute,
+  // SetVariable must be used with attributes matching the existing variable
+  // and the DataSize set to the size of the AuthInfo descriptor.
+  //
+  if ((Variable->CurrPtr != NULL) &&
+      (Attributes == Variable->CurrPtr->Attributes) &&
+      ((Attributes & (EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS | EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) != 0)) {
+    if ((Attributes & EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) != 0) {
+      Payload = (UINT8 *) Data + AUTHINFO2_SIZE (Data);
+      PayloadSize = DataSize - AUTHINFO2_SIZE (Data);
+      if (PayloadSize == 0) {
+        Del = TRUE;
+      }
+    } else {
+      Payload = (UINT8 *) Data + AUTHINFO_SIZE;
+      PayloadSize = DataSize - AUTHINFO_SIZE;
+      if (PayloadSize == 0) {
+        Del = TRUE;
+      }
+    }
+  }
+
+  return Del;
+}
+
 /**
   Process variable with EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS/EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS set
 
@@ -1295,8 +1318,7 @@ ProcessVarWithKek (
   @param[in]  VendorGuid                  Variable vendor GUID.
 
   @param[in]  Data                        Data pointer.
-  @param[in]  DataSize                    Size of Data found. If size is less than the
+  @param[in]  DataSize                    Size of Data.
-                                          data, this value contains the required size.
   @param[in]  Variable                    The variable information which is used to keep track of variable usage.
   @param[in]  Attributes                  Attribute value of the variable.
 
@@ -1336,11 +1358,36 @@ ProcessVariable (
   PubKey      = NULL;
   IsDeletion  = FALSE;
 
-  if (NeedPhysicallyPresent(VariableName, VendorGuid) && !UserPhysicalPresent()) {
+  if (UserPhysicalPresent()) {
     //
-    // This variable is protected, only physical present user could modify its value.
+    // Allow the delete operation of common authenticated variable at user physical presence.
     //
-    return EFI_SECURITY_VIOLATION;
+    if (IsDeleteAuthVariable (Data, DataSize, Variable, Attributes)) {
+      if ((Attributes & EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) != 0) {
+        Status = DeleteCertsFromDb (VariableName, VendorGuid);
+      }
+      if (!EFI_ERROR (Status)) {
+        Status = UpdateVariable (
+                   VariableName,
+                   VendorGuid,
+                   NULL,
+                   0,
+                   0,
+                   0,
+                   0,
+                   Variable,
+                   NULL
+                   );
+      }
+      return Status;
+    }
+  } else {
+    if (NeedPhysicallyPresent(VariableName, VendorGuid)) {
+      //
+      // This variable is protected, only physical present user could modify its value.
+      //
+      return EFI_SECURITY_VIOLATION;
+    }
   }
 
   //

SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.h

@@ -12,7 +12,7 @@
   may not be modified without authorization. If platform fails to protect these resources, 
   the authentication service provided in this driver will be broken, and the behavior is undefined.
 
-Copyright (c) 2009 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2009 - 2015, 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
@@ -289,6 +289,24 @@ CompareTimeStamp (
   IN EFI_TIME               *SecondTime
   );
 
+/**
+  Delete matching signer's certificates when deleting common authenticated
+  variable by corresponding VariableName and VendorGuid from "certdb".
+
+  @param[in]  VariableName   Name of authenticated Variable.
+  @param[in]  VendorGuid     Vendor GUID of authenticated Variable.
+
+  @retval  EFI_INVALID_PARAMETER Any input parameter is invalid.
+  @retval  EFI_NOT_FOUND         Fail to find "certdb" or matching certs.
+  @retval  EFI_OUT_OF_RESOURCES  The operation is failed due to lack of resources.
+  @retval  EFI_SUCCESS           The operation is completed successfully.
+
+**/
+EFI_STATUS
+DeleteCertsFromDb (
+  IN     CHAR16           *VariableName,
+  IN     EFI_GUID         *VendorGuid
+  );
 
 /**
   Process variable with EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS set

SecurityPkg/VariableAuthenticated/RuntimeDxe/VarCheck.c

@@ -13,6 +13,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 **/
 
 #include "Variable.h"
+#include "AuthService.h"
 #include <Library/DevicePathLib.h>
 
 extern LIST_ENTRY mLockedVariableList;
@@ -668,7 +669,7 @@ VARIABLE_DRIVER_VARIABLE_ENTRY mVariableDriverVariableList[] = {
     EFI_VENDOR_KEYS_NV_VARIABLE_NAME,
     {
       VAR_CHECK_VARIABLE_PROPERTY_REVISION,
-      0,
+      VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY,
       VARIABLE_ATTRIBUTE_NV_BS_RT_AT,
       sizeof (UINT8),
       sizeof (UINT8)
@@ -676,10 +677,10 @@ VARIABLE_DRIVER_VARIABLE_ENTRY mVariableDriverVariableList[] = {
   },
   {
     &gEfiAuthenticatedVariableGuid,
-    L"AuthVarKeyDatabase",
+    AUTHVAR_KEYDB_NAME,
     {
       VAR_CHECK_VARIABLE_PROPERTY_REVISION,
-      0,
+      VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY,
       VARIABLE_ATTRIBUTE_NV_BS_RT_AW,
       sizeof (UINT8),
       MAX_UINTN
@@ -687,10 +688,10 @@ VARIABLE_DRIVER_VARIABLE_ENTRY mVariableDriverVariableList[] = {
   },
   {
     &gEfiCertDbGuid,
-    L"certdb",
+    EFI_CERT_DB_NAME,
     {
       VAR_CHECK_VARIABLE_PROPERTY_REVISION,
-      0,
+      VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY,
       VARIABLE_ATTRIBUTE_NV_BS_RT_AT,
       sizeof (UINT32),
       MAX_UINTN