SecurityPkg: DxeTpm2MeasureBootLib: SECURITY PATCH 4118 - CVE 2022-36764

This commit contains the patch files and tests for DxeTpm2MeasureBootLib
CVE 2022-36764.

Cc: Jiewen Yao <[email protected]>

Signed-off-by: Doug Flick [MSFT] <[email protected]>
Reviewed-by: Jiewen Yao <[email protected]>

Author: Douglas Flick [MSFT]

SecurityPkg/Library/DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLib.c

@@ -378,7 +378,6 @@ Tcg2MeasureGptTable (
   @retval EFI_OUT_OF_RESOURCES   No enough resource to measure image.
   @retval EFI_UNSUPPORTED        ImageType is unsupported or PE image is mal-format.
   @retval other error value
-
 **/
 EFI_STATUS
 EFIAPI
@@ -405,6 +404,7 @@ Tcg2MeasurePeImage (
   Status    = EFI_UNSUPPORTED;
   ImageLoad = NULL;
   EventPtr  = NULL;
+  Tcg2Event = NULL;
 
   Tcg2Protocol = MeasureBootProtocols->Tcg2Protocol;
   CcProtocol   = MeasureBootProtocols->CcProtocol;
@@ -420,18 +420,22 @@ Tcg2MeasurePeImage (
   }
 
   FilePathSize = (UINT32)GetDevicePathSize (FilePath);
+  Status       = SanitizePeImageEventSize (FilePathSize, &EventSize);
+  if (EFI_ERROR (Status)) {
+    return EFI_UNSUPPORTED;
+  }
 
   //
   // Determine destination PCR by BootPolicy
   //
-  EventSize = sizeof (*ImageLoad) - sizeof (ImageLoad->DevicePath) + FilePathSize;
-  EventPtr  = AllocateZeroPool (EventSize + sizeof (EFI_TCG2_EVENT) - sizeof (Tcg2Event->Event));
+  // from a malicious GPT disk partition
+  EventPtr = AllocateZeroPool (EventSize);
   if (EventPtr == NULL) {
     return EFI_OUT_OF_RESOURCES;
   }
 
   Tcg2Event                       = (EFI_TCG2_EVENT *)EventPtr;
-  Tcg2Event->Size                 = EventSize + sizeof (EFI_TCG2_EVENT) - sizeof (Tcg2Event->Event);
+  Tcg2Event->Size                 = EventSize;
   Tcg2Event->Header.HeaderSize    = sizeof (EFI_TCG2_EVENT_HEADER);
   Tcg2Event->Header.HeaderVersion = EFI_TCG2_EVENT_HEADER_VERSION;
   ImageLoad                       = (EFI_IMAGE_LOAD_EVENT *)Tcg2Event->Event;

SecurityPkg/Library/DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLibSanitization.c

@@ -151,7 +151,7 @@ SanitizeEfiPartitionTableHeader (
 }
 
 /**
-  This function will validate that the allocation size from the primary header is sane
+ This function will validate that the allocation size from the primary header is sane
   It will check the following:
     - AllocationSize does not overflow
 
@@ -273,3 +273,47 @@ SanitizePrimaryHeaderGptEventSize (
 
   return EFI_SUCCESS;
 }
+
+/**
+  This function will validate that the PeImage Event Size from the loaded image is sane
+  It will check the following:
+    - EventSize does not overflow
+
+  @param[in] FilePathSize - Size of the file path.
+  @param[out] EventSize - Pointer to the event size.
+
+  @retval EFI_SUCCESS
+    The event size is valid.
+
+  @retval EFI_OUT_OF_RESOURCES
+    Overflow would have occurred.
+
+  @retval EFI_INVALID_PARAMETER
+    One of the passed parameters was invalid.
+**/
+EFI_STATUS
+SanitizePeImageEventSize (
+  IN  UINT32  FilePathSize,
+  OUT UINT32  *EventSize
+  )
+{
+  EFI_STATUS  Status;
+
+  // Replacing logic:
+  // sizeof (*ImageLoad) - sizeof (ImageLoad->DevicePath) + FilePathSize;
+  Status = SafeUint32Add (OFFSET_OF (EFI_IMAGE_LOAD_EVENT, DevicePath), FilePathSize, EventSize);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "EventSize would overflow!\n"));
+    return EFI_BAD_BUFFER_SIZE;
+  }
+
+  // Replacing logic:
+  // EventSize + sizeof (EFI_TCG2_EVENT) - sizeof (Tcg2Event->Event)
+  Status = SafeUint32Add (*EventSize, OFFSET_OF (EFI_TCG2_EVENT, Event), EventSize);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "EventSize would overflow!\n"));
+    return EFI_BAD_BUFFER_SIZE;
+  }
+
+  return EFI_SUCCESS;
+}

SecurityPkg/Library/DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLibSanitization.h

@@ -9,6 +9,9 @@
   Tcg2MeasureGptTable() function will receive untrusted GPT partition table, and parse
   partition data carefully.
 
+  Tcg2MeasurePeImage() function will accept untrusted PE/COFF image and validate its
+  data structure within this image buffer before use.
+
   Copyright (c) Microsoft Corporation.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -110,4 +113,27 @@ SanitizePrimaryHeaderGptEventSize (
   OUT UINT32                            *EventSize
   );
 
-#endif // DXE_TPM2_MEASURE_BOOT_LIB_SANITATION_
+/**
+  This function will validate that the PeImage Event Size from the loaded image is sane
+  It will check the following:
+    - EventSize does not overflow
+
+  @param[in] FilePathSize - Size of the file path.
+  @param[out] EventSize - Pointer to the event size.
+
+  @retval EFI_SUCCESS
+    The event size is valid.
+
+  @retval EFI_OUT_OF_RESOURCES
+    Overflow would have occurred.
+
+  @retval EFI_INVALID_PARAMETER
+    One of the passed parameters was invalid.
+**/
+EFI_STATUS
+SanitizePeImageEventSize (
+  IN  UINT32  FilePathSize,
+  OUT UINT32  *EventSize
+  );
+
+#endif // DXE_TPM2_MEASURE_BOOT_LIB_VALIDATION_

SecurityPkg/Library/DxeTpm2MeasureBootLib/InternalUnitTest/DxeTpm2MeasureBootLibSanitizationTest.c

@@ -72,10 +72,10 @@ TestSanitizeEfiPartitionTableHeader (
   PrimaryHeader.Header.Revision          = DEFAULT_PRIMARY_TABLE_HEADER_REVISION;
   PrimaryHeader.Header.HeaderSize        = sizeof (EFI_PARTITION_TABLE_HEADER);
   PrimaryHeader.MyLBA                    = 1;
-  PrimaryHeader.AlternateLBA             = 2;
-  PrimaryHeader.FirstUsableLBA           = 3;
-  PrimaryHeader.LastUsableLBA            = 4;
-  PrimaryHeader.PartitionEntryLBA        = 5;
+  PrimaryHeader.PartitionEntryLBA        = 2;
+  PrimaryHeader.AlternateLBA             = 3;
+  PrimaryHeader.FirstUsableLBA           = 4;
+  PrimaryHeader.LastUsableLBA            = 5;
   PrimaryHeader.NumberOfPartitionEntries = DEFAULT_PRIMARY_TABLE_HEADER_NUMBER_OF_PARTITION_ENTRIES;
   PrimaryHeader.SizeOfPartitionEntry     = DEFAULT_PRIMARY_TABLE_HEADER_SIZE_OF_PARTITION_ENTRY;
   PrimaryHeader.PartitionEntryArrayCRC32 = 0; // Purposely invalid
@@ -187,11 +187,6 @@ TestSanitizePrimaryHeaderGptEventSize (
   EFI_STATUS                  Status;
   EFI_PARTITION_TABLE_HEADER  PrimaryHeader;
   UINTN                       NumberOfPartition;
-  EFI_GPT_DATA                *GptData;
-  EFI_TCG2_EVENT              *Tcg2Event;
-
-  Tcg2Event = NULL;
-  GptData   = NULL;
 
   // Test that a normal PrimaryHeader passes validation
   PrimaryHeader.NumberOfPartitionEntries = 5;
@@ -225,6 +220,52 @@ TestSanitizePrimaryHeaderGptEventSize (
   return UNIT_TEST_PASSED;
 }
 
+/**
+  This function tests the SanitizePeImageEventSize function.
+  It's intent is to test that the untrusted input from a file path when generating a
+  EFI_IMAGE_LOAD_EVENT structure will not cause an overflow when calculating
+  the event size when allocating space
+
+  @param[in] Context  The unit test context.
+
+  @retval UNIT_TEST_PASSED  The test passed.
+  @retval UNIT_TEST_ERROR_TEST_FAILED  The test failed.
+**/
+UNIT_TEST_STATUS
+EFIAPI
+TestSanitizePeImageEventSize (
+  IN UNIT_TEST_CONTEXT  Context
+  )
+{
+  UINT32      EventSize;
+  UINTN       ExistingLogicEventSize;
+  UINT32      FilePathSize;
+  EFI_STATUS  Status;
+
+  FilePathSize = 255;
+
+  // Test that a normal PE image passes validation
+  Status = SanitizePeImageEventSize (FilePathSize, &EventSize);
+  UT_ASSERT_EQUAL (Status, EFI_SUCCESS);
+
+  // Test that the event size is correct compared to the existing logic
+  ExistingLogicEventSize  = OFFSET_OF (EFI_IMAGE_LOAD_EVENT, DevicePath) + FilePathSize;
+  ExistingLogicEventSize += OFFSET_OF (EFI_TCG2_EVENT, Event);
+
+  if (EventSize != ExistingLogicEventSize) {
+    UT_LOG_ERROR ("SanitizePeImageEventSize returned an incorrect event size. Expected %u, got %u\n", ExistingLogicEventSize, EventSize);
+    return UNIT_TEST_ERROR_TEST_FAILED;
+  }
+
+  // Test that the event size may not overflow
+  Status = SanitizePeImageEventSize (MAX_UINT32, &EventSize);
+  UT_ASSERT_EQUAL (Status, EFI_BAD_BUFFER_SIZE);
+
+  DEBUG ((DEBUG_INFO, "%a: Test passed\n", __func__));
+
+  return UNIT_TEST_PASSED;
+}
+
 // *--------------------------------------------------------------------*
 // *  Unit Test Code Main Function
 // *--------------------------------------------------------------------*
@@ -267,6 +308,7 @@ UefiTestMain (
   AddTestCase (Tcg2MeasureBootLibValidationTestSuite, "Tests Validating EFI Partition Table", "Common.Tcg2MeasureBootLibValidation", TestSanitizeEfiPartitionTableHeader, NULL, NULL, NULL);
   AddTestCase (Tcg2MeasureBootLibValidationTestSuite, "Tests Primary header gpt event checks for overflow", "Common.Tcg2MeasureBootLibValidation", TestSanitizePrimaryHeaderAllocationSize, NULL, NULL, NULL);
   AddTestCase (Tcg2MeasureBootLibValidationTestSuite, "Tests Primary header allocation size checks for overflow", "Common.Tcg2MeasureBootLibValidation", TestSanitizePrimaryHeaderGptEventSize, NULL, NULL, NULL);
+  AddTestCase (Tcg2MeasureBootLibValidationTestSuite, "Tests PE Image and FileSize checks for overflow", "Common.Tcg2MeasureBootLibValidation", TestSanitizePeImageEventSize, NULL, NULL, NULL);
 
   Status = RunAllTestSuites (Framework);