StandaloneMmPkg/Core: permit encapsulated firmware volumes

Standalone MM requires 4 KB section alignment for all images, so that
strict permissions can be applied. Unfortunately, this results in a
lot of wasted space, which is usually costly in the secure world
environment that standalone MM is expected to operate in.

So let's permit the standalone MM drivers (but not the core) to be
delivered in a compressed firmware volume.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: "Yao, Jiewen" <jiewen.yao@intel.com>
Reviewed-by: Achin Gupta <achin.gupta@arm.com>

StandaloneMmPkg/Core/FwVol.c

@@ -14,6 +14,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 #include "StandaloneMmCore.h"
 #include <Library/FvLib.h>
+#include <Library/ExtractGuidedSectionLib.h>
 
 //
 // List of file types supported by dispatcher
@@ -74,6 +75,16 @@ Returns:
   VOID                                    *Depex;
   UINTN                                   DepexSize;
   UINTN                                   Index;
+  EFI_COMMON_SECTION_HEADER               *Section;
+  VOID                                    *SectionData;
+  UINTN                                   SectionDataSize;
+  UINT32                                  DstBufferSize;
+  VOID                                    *ScratchBuffer;
+  UINT32                                  ScratchBufferSize;
+  VOID                                    *DstBuffer;
+  UINT16                                  SectionAttribute;
+  UINT32                                  AuthenticationStatus;
+  EFI_FIRMWARE_VOLUME_HEADER              *InnerFvHeader;
 
   DEBUG ((DEBUG_INFO, "MmCoreFfsFindMmDriver - 0x%x\n", FwVolHeader));
 
@@ -83,6 +94,71 @@ Returns:
 
   FvIsBeingProcesssed (FwVolHeader);
 
+  //
+  // First check for encapsulated compressed firmware volumes
+  //
+  FileHeader = NULL;
+  do {
+    Status = FfsFindNextFile (EFI_FV_FILETYPE_FIRMWARE_VOLUME_IMAGE,
+               FwVolHeader, &FileHeader);
+    if (EFI_ERROR (Status)) {
+      break;
+    }
+    Status = FfsFindSectionData (EFI_SECTION_GUID_DEFINED, FileHeader,
+               &SectionData, &SectionDataSize);
+    if (EFI_ERROR (Status)) {
+      break;
+    }
+    Section = (EFI_COMMON_SECTION_HEADER *)(FileHeader + 1);
+    Status = ExtractGuidedSectionGetInfo (Section, &DstBufferSize,
+               &ScratchBufferSize, &SectionAttribute);
+    if (EFI_ERROR (Status)) {
+      break;
+    }
+
+    //
+    // Allocate scratch buffer
+    //
+    ScratchBuffer = (VOID *)(UINTN)AllocatePages (EFI_SIZE_TO_PAGES (ScratchBufferSize));
+    if (ScratchBuffer == NULL) {
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    //
+    // Allocate destination buffer, extra one page for adjustment
+    //
+    DstBuffer = (VOID *)(UINTN)AllocatePages (EFI_SIZE_TO_PAGES (DstBufferSize));
+    if (DstBuffer == NULL) {
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    //
+    // Call decompress function
+    //
+    Status = ExtractGuidedSectionDecode (Section, &DstBuffer, ScratchBuffer,
+                &AuthenticationStatus);
+    FreePages (ScratchBuffer, EFI_SIZE_TO_PAGES (ScratchBufferSize));
+    if (EFI_ERROR (Status)) {
+      goto FreeDstBuffer;
+    }
+
+    DEBUG ((DEBUG_INFO,
+      "Processing compressed firmware volume (AuthenticationStatus == %x)\n",
+      AuthenticationStatus));
+
+    Status = FindFfsSectionInSections (DstBuffer, DstBufferSize,
+               EFI_SECTION_FIRMWARE_VOLUME_IMAGE, &Section);
+    if (EFI_ERROR (Status)) {
+      goto FreeDstBuffer;
+    }
+
+    InnerFvHeader = (VOID *)(Section + 1);
+    Status = MmCoreFfsFindMmDriver (InnerFvHeader);
+    if (EFI_ERROR (Status)) {
+      goto FreeDstBuffer;
+    }
+  } while (TRUE);
+
   for (Index = 0; Index < sizeof (mMmFileTypes) / sizeof (mMmFileTypes[0]); Index++) {
     DEBUG ((DEBUG_INFO, "Check MmFileTypes - 0x%x\n", mMmFileTypes[Index]));
     FileType = mMmFileTypes[Index];
@@ -100,5 +176,10 @@ Returns:
     } while (!EFI_ERROR (Status));
   }
 
+  return EFI_SUCCESS;
+
+FreeDstBuffer:
+  FreePages (DstBuffer, EFI_SIZE_TO_PAGES (DstBufferSize));
+
   return Status;
 }

StandaloneMmPkg/Core/StandaloneMmCore.inf

@@ -49,6 +49,7 @@
   BaseMemoryLib
   CacheMaintenanceLib
   DebugLib
+  ExtractGuidedSectionLib
   FvLib
   HobLib
   MemoryAllocationLib