Add comments to clarify mPubKeyStore buffer MemCopy. There is no memory overflow issue.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chao, Zhang <chao.b.zhang@intel.com>
Reviewed-by: Yao, Jiewen <jiewen.yao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16227 6f19259b-4bc3-4df7-8a09-765794883524

4 files changed, 30 insertions, 0 deletions

diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.c b/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.c
index 49d7648f6..566c5e29a 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.c
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.c
@@ -7,6 +7,10 @@
   This external input must be validated carefully to avoid security issue like

   buffer overflow, integer overflow.

   Variable attribute should also be checked to avoid authentication bypass.

+     The whole SMM authentication variable design relies on the integrity of flash part and SMM.

+  which is assumed to be protected by platform.  All variable code and metadata in flash/SMM Memory

+  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.

 

   ProcessVarWithPk(), ProcessVarWithKek() and ProcessVariable() are the function to do

   variable authentication.

@@ -251,6 +255,10 @@ AutenticatedVariableServiceInitialize (
     DataSize  = DataSizeOfVariable (Variable.CurrPtr);

     Data      = GetVariableDataPtr (Variable.CurrPtr);

     ASSERT ((DataSize != 0) && (Data != NULL));

+    //

+    // "AuthVarKeyDatabase" is an internal variable. Its DataSize is always ensured not to exceed mPubKeyStore buffer size(See definition before) 

+    //  Therefore, there is no memory overflow in underlying CopyMem.

+    //

     CopyMem (mPubKeyStore, (UINT8 *) Data, DataSize);

     mPubKeyNumber = (UINT32) (DataSize / EFI_CERT_TYPE_RSA2048_SIZE);

   }

@@ -564,6 +572,10 @@ AddPubKeyInStore (
       DataSize  = DataSizeOfVariable (Variable.CurrPtr);

       Data      = GetVariableDataPtr (Variable.CurrPtr);

       ASSERT ((DataSize != 0) && (Data != NULL));

+      //

+      // "AuthVarKeyDatabase" is an internal used variable. Its DataSize is always ensured not to exceed mPubKeyStore buffer size(See definition before) 

+      //  Therefore, there is no memory overflow in underlying CopyMem.

+      //

       CopyMem (mPubKeyStore, (UINT8 *) Data, DataSize);

       mPubKeyNumber = (UINT32) (DataSize / EFI_CERT_TYPE_RSA2048_SIZE);

 

diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.h b/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.h
index 6ebc77707..0e57c5b5e 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.h
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/AuthService.h
@@ -2,6 +2,16 @@
   The internal header file includes the common header files, defines

   internal structure and functions used by AuthService module.

 

+  Caution: This module requires additional review when modified.

+  This driver will have external input - variable data. It may be input in SMM mode.

+  This external input must be validated carefully to avoid security issue like

+  buffer overflow, integer overflow.

+  Variable attribute should also be checked to avoid authentication bypass.

+     The whole SMM authentication variable design relies on the integrity of flash part and SMM.

+  which is assumed to be protected by platform.  All variable code and metadata in flash/SMM Memory

+  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>

 This program and the accompanying materials

 are licensed and made available under the terms and conditions of the BSD License

diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.inf b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.inf
index 279a9248e..1987764d8 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.inf
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.inf
@@ -13,6 +13,10 @@
 #  This driver will have external input - variable data and communicate buffer in SMM mode.

 #  This external input must be validated carefully to avoid security issues such as 

 #  buffer overflow or integer overflow.

+#    The whole SMM authentication variable design relies on the integrity of flash part and SMM.

+#  which is assumed to be protected by platform.  All variable code and metadata in flash/SMM Memory

+#  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) 2010 - 2014, Intel Corporation. All rights reserved.<BR>

 # This program and the accompanying materials

diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmmRuntimeDxe.inf b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmmRuntimeDxe.inf
index f0dfa8981..ca6027433 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmmRuntimeDxe.inf
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmmRuntimeDxe.inf
@@ -8,6 +8,10 @@
 #  This driver will have external input - variable data.

 #  This external input must be validated carefully to avoid security issues such as 

 #  buffer overflow or integer overflow.

+#    The whole SMM authentication variable design relies on the integrity of flash part and SMM.

+#  which is assumed to be protected by platform.  All variable code and metadata in flash/SMM Memory

+#  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) 2010 - 2014, Intel Corporation. All rights reserved.<BR>

 # This program and the accompanying materials