[PATCH 07/11] SecurityPkg/DxeImageVerificationHandler: unnest AddImageExeInfo() call

["Laszlo Ersek" <lersek@redhat.com>]

Before the "Done" label at the end of DxeImageVerificationHandler(), we
now have a single access to "Status": we set "Status" to EFI_ACCESS_DENIED
at the top of the function. Therefore, the (Status != EFI_SUCCESS)
condition is always true under the "Done" label.

Accordingly, unnest the AddImageExeInfo() call dependent on that
condition, remove the condition, and also rename the "Done" label to
"Failed".

Functionally, this patch is a no-op. It's easier to review with:

  git show -b -W

Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2129
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c | 34 +++++++++-----------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c b/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
index 6ccce1f35843..b98404ab465b 100644
--- a/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
+++ b/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
@@ -1555,348 +1555,346 @@ EFIAPI
 DxeImageVerificationHandler (
   IN  UINT32                           AuthenticationStatus,
   IN  CONST EFI_DEVICE_PATH_PROTOCOL   *File,
   IN  VOID                             *FileBuffer,
   IN  UINTN                            FileSize,
   IN  BOOLEAN                          BootPolicy
   )
 {
   EFI_STATUS                           Status;
   EFI_IMAGE_DOS_HEADER                 *DosHdr;
   BOOLEAN                              IsVerified;
   EFI_SIGNATURE_LIST                   *SignatureList;
   UINTN                                SignatureListSize;
   EFI_SIGNATURE_DATA                   *Signature;
   EFI_IMAGE_EXECUTION_ACTION           Action;
   WIN_CERTIFICATE                      *WinCertificate;
   UINT32                               Policy;
   UINT8                                *SecureBoot;
   PE_COFF_LOADER_IMAGE_CONTEXT         ImageContext;
   UINT32                               NumberOfRvaAndSizes;
   WIN_CERTIFICATE_EFI_PKCS             *PkcsCertData;
   WIN_CERTIFICATE_UEFI_GUID            *WinCertUefiGuid;
   UINT8                                *AuthData;
   UINTN                                AuthDataSize;
   EFI_IMAGE_DATA_DIRECTORY             *SecDataDir;
   UINT32                               OffSet;
   CHAR16                               *NameStr;
   RETURN_STATUS                        PeCoffStatus;
   EFI_STATUS                           HashStatus;
 
   SignatureList     = NULL;
   SignatureListSize = 0;
   WinCertificate    = NULL;
   SecDataDir        = NULL;
   PkcsCertData      = NULL;
   Action            = EFI_IMAGE_EXECUTION_AUTH_UNTESTED;
   Status            = EFI_ACCESS_DENIED;
   IsVerified        = FALSE;
 
 
   //
   // Check the image type and get policy setting.
   //
   switch (GetImageType (File)) {
 
   case IMAGE_FROM_FV:
     Policy = ALWAYS_EXECUTE;
     break;
 
   case IMAGE_FROM_OPTION_ROM:
     Policy = PcdGet32 (PcdOptionRomImageVerificationPolicy);
     break;
 
   case IMAGE_FROM_REMOVABLE_MEDIA:
     Policy = PcdGet32 (PcdRemovableMediaImageVerificationPolicy);
     break;
 
   case IMAGE_FROM_FIXED_MEDIA:
     Policy = PcdGet32 (PcdFixedMediaImageVerificationPolicy);
     break;
 
   default:
     Policy = DENY_EXECUTE_ON_SECURITY_VIOLATION;
     break;
   }
   //
   // If policy is always/never execute, return directly.
   //
   if (Policy == ALWAYS_EXECUTE) {
     return EFI_SUCCESS;
   }
   if (Policy == NEVER_EXECUTE) {
     return EFI_ACCESS_DENIED;
   }
 
   //
   // The policy QUERY_USER_ON_SECURITY_VIOLATION and ALLOW_EXECUTE_ON_SECURITY_VIOLATION
   // violates the UEFI spec and has been removed.
   //
   ASSERT (Policy != QUERY_USER_ON_SECURITY_VIOLATION && Policy != ALLOW_EXECUTE_ON_SECURITY_VIOLATION);
   if (Policy == QUERY_USER_ON_SECURITY_VIOLATION || Policy == ALLOW_EXECUTE_ON_SECURITY_VIOLATION) {
     CpuDeadLoop ();
   }
 
   GetEfiGlobalVariable2 (EFI_SECURE_BOOT_MODE_NAME, (VOID**)&SecureBoot, NULL);
   //
   // Skip verification if SecureBoot variable doesn't exist.
   //
   if (SecureBoot == NULL) {
     return EFI_SUCCESS;
   }
 
   //
   // Skip verification if SecureBoot is disabled but not AuditMode
   //
   if (*SecureBoot == SECURE_BOOT_MODE_DISABLE) {
     FreePool (SecureBoot);
     return EFI_SUCCESS;
   }
   FreePool (SecureBoot);
 
   //
   // Read the Dos header.
   //
   if (FileBuffer == NULL) {
     return EFI_INVALID_PARAMETER;
   }
 
   mImageBase  = (UINT8 *) FileBuffer;
   mImageSize  = FileSize;
 
   ZeroMem (&ImageContext, sizeof (ImageContext));
   ImageContext.Handle    = (VOID *) FileBuffer;
   ImageContext.ImageRead = (PE_COFF_LOADER_READ_FILE) DxeImageVerificationLibImageRead;
 
   //
   // Get information about the image being loaded
   //
   PeCoffStatus = PeCoffLoaderGetImageInfo (&ImageContext);
   if (RETURN_ERROR (PeCoffStatus)) {
     //
     // The information can't be got from the invalid PeImage
     //
     DEBUG ((DEBUG_INFO, "DxeImageVerificationLib: PeImage invalid. Cannot retrieve image information.\n"));
-    goto Done;
+    goto Failed;
   }
 
   DosHdr = (EFI_IMAGE_DOS_HEADER *) mImageBase;
   if (DosHdr->e_magic == EFI_IMAGE_DOS_SIGNATURE) {
     //
     // DOS image header is present,
     // so read the PE header after the DOS image header.
     //
     mPeCoffHeaderOffset = DosHdr->e_lfanew;
   } else {
     mPeCoffHeaderOffset = 0;
   }
   //
   // Check PE/COFF image.
   //
   mNtHeader.Pe32 = (EFI_IMAGE_NT_HEADERS32 *) (mImageBase + mPeCoffHeaderOffset);
   if (mNtHeader.Pe32->Signature != EFI_IMAGE_NT_SIGNATURE) {
     //
     // It is not a valid Pe/Coff file.
     //
     DEBUG ((DEBUG_INFO, "DxeImageVerificationLib: Not a valid PE/COFF image.\n"));
-    goto Done;
+    goto Failed;
   }
 
   if (mNtHeader.Pe32->OptionalHeader.Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
     //
     // Use PE32 offset.
     //
     NumberOfRvaAndSizes = mNtHeader.Pe32->OptionalHeader.NumberOfRvaAndSizes;
     if (NumberOfRvaAndSizes > EFI_IMAGE_DIRECTORY_ENTRY_SECURITY) {
       SecDataDir = (EFI_IMAGE_DATA_DIRECTORY *) &mNtHeader.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY];
     }
   } else {
     //
     // Use PE32+ offset.
     //
     NumberOfRvaAndSizes = mNtHeader.Pe32Plus->OptionalHeader.NumberOfRvaAndSizes;
     if (NumberOfRvaAndSizes > EFI_IMAGE_DIRECTORY_ENTRY_SECURITY) {
       SecDataDir = (EFI_IMAGE_DATA_DIRECTORY *) &mNtHeader.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY];
     }
   }
 
   //
   // Start Image Validation.
   //
   if (SecDataDir == NULL || SecDataDir->Size == 0) {
     //
     // This image is not signed. The SHA256 hash value of the image must match a record in the security database "db",
     // and not be reflected in the security data base "dbx".
     //
     if (!HashPeImage (HASHALG_SHA256)) {
       DEBUG ((DEBUG_INFO, "DxeImageVerificationLib: Failed to hash this image using %s.\n", mHashTypeStr));
-      goto Done;
+      goto Failed;
     }
 
     if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE1, mImageDigest, &mCertType, mImageDigestSize)) {
       //
       // Image Hash is in forbidden database (DBX).
       //
       DEBUG ((DEBUG_INFO, "DxeImageVerificationLib: Image is not signed and %s hash of image is forbidden by DBX.\n", mHashTypeStr));
-      goto Done;
+      goto Failed;
     }
 
     if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE, mImageDigest, &mCertType, mImageDigestSize)) {
       //
       // Image Hash is in allowed database (DB).
       //
       return EFI_SUCCESS;
     }
 
     //
     // Image Hash is not found in both forbidden and allowed database.
     //
     DEBUG ((DEBUG_INFO, "DxeImageVerificationLib: Image is not signed and %s hash of image is not found in DB/DBX.\n", mHashTypeStr));
-    goto Done;
+    goto Failed;
   }
 
   //
   // Verify the signature of the image, multiple signatures are allowed as per PE/COFF Section 4.7
   // "Attribute Certificate Table".
   // The first certificate starts at offset (SecDataDir->VirtualAddress) from the start of the file.
   //
   for (OffSet = SecDataDir->VirtualAddress;
        OffSet < (SecDataDir->VirtualAddress + SecDataDir->Size);
        OffSet += (WinCertificate->dwLength + ALIGN_SIZE (WinCertificate->dwLength))) {
     WinCertificate = (WIN_CERTIFICATE *) (mImageBase + OffSet);
     if ((SecDataDir->VirtualAddress + SecDataDir->Size - OffSet) <= sizeof (WIN_CERTIFICATE) ||
         (SecDataDir->VirtualAddress + SecDataDir->Size - OffSet) < WinCertificate->dwLength) {
       break;
     }
 
     //
     // Verify the image's Authenticode signature, only DER-encoded PKCS#7 signed data is supported.
     //
     if (WinCertificate->wCertificateType == WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
       //
       // The certificate is formatted as WIN_CERTIFICATE_EFI_PKCS which is described in the
       // Authenticode specification.
       //
       PkcsCertData = (WIN_CERTIFICATE_EFI_PKCS *) WinCertificate;
       if (PkcsCertData->Hdr.dwLength <= sizeof (PkcsCertData->Hdr)) {
         break;
       }
       AuthData   = PkcsCertData->CertData;
       AuthDataSize = PkcsCertData->Hdr.dwLength - sizeof(PkcsCertData->Hdr);
     } else if (WinCertificate->wCertificateType == WIN_CERT_TYPE_EFI_GUID) {
       //
       // The certificate is formatted as WIN_CERTIFICATE_UEFI_GUID which is described in UEFI Spec.
       //
       WinCertUefiGuid = (WIN_CERTIFICATE_UEFI_GUID *) WinCertificate;
       if (WinCertUefiGuid->Hdr.dwLength <= OFFSET_OF(WIN_CERTIFICATE_UEFI_GUID, CertData)) {
         break;
       }
       if (!CompareGuid (&WinCertUefiGuid->CertType, &gEfiCertPkcs7Guid)) {
         continue;
       }
       AuthData = WinCertUefiGuid->CertData;
       AuthDataSize = WinCertUefiGuid->Hdr.dwLength - OFFSET_OF(WIN_CERTIFICATE_UEFI_GUID, CertData);
     } else {
       if (WinCertificate->dwLength < sizeof (WIN_CERTIFICATE)) {
         break;
       }
       continue;
     }
 
     HashStatus = HashPeImageByType (AuthData, AuthDataSize);
     if (EFI_ERROR (HashStatus)) {
       continue;
     }
 
     //
     // Check the digital signature against the revoked certificate in forbidden database (dbx).
     //
     if (IsForbiddenByDbx (AuthData, AuthDataSize)) {
       Action = EFI_IMAGE_EXECUTION_AUTH_SIG_FAILED;
       IsVerified = FALSE;
       break;
     }
 
     //
     // Check the digital signature against the valid certificate in allowed database (db).
     //
     if (!IsVerified) {
       if (IsAllowedByDb (AuthData, AuthDataSize)) {
         IsVerified = TRUE;
       }
     }
 
     //
     // Check the image's hash value.
     //
     if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE1, mImageDigest, &mCertType, mImageDigestSize)) {
       Action = EFI_IMAGE_EXECUTION_AUTH_SIG_FOUND;
       DEBUG ((DEBUG_INFO, "DxeImageVerificationLib: Image is signed but %s hash of image is found in DBX.\n", mHashTypeStr));
       IsVerified = FALSE;
       break;
     }
     if (!IsVerified) {
       if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE, mImageDigest, &mCertType, mImageDigestSize)) {
         IsVerified = TRUE;
       } else {
         DEBUG ((DEBUG_INFO, "DxeImageVerificationLib: Image is signed but signature is not allowed by DB and %s hash of image is not found in DB/DBX.\n", mHashTypeStr));
       }
     }
   }
 
   if (OffSet != (SecDataDir->VirtualAddress + SecDataDir->Size)) {
     //
     // The Size in Certificate Table or the attribute certificate table is corrupted.
     //
     IsVerified = FALSE;
   }
 
   if (IsVerified) {
     return EFI_SUCCESS;
   }
   if (Action == EFI_IMAGE_EXECUTION_AUTH_SIG_FAILED || Action == EFI_IMAGE_EXECUTION_AUTH_SIG_FOUND) {
     //
     // Get image hash value as signature of executable.
     //
     SignatureListSize = sizeof (EFI_SIGNATURE_LIST) + sizeof (EFI_SIGNATURE_DATA) - 1 + mImageDigestSize;
     SignatureList     = (EFI_SIGNATURE_LIST *) AllocateZeroPool (SignatureListSize);
     if (SignatureList == NULL) {
-      goto Done;
+      goto Failed;
     }
     SignatureList->SignatureHeaderSize  = 0;
     SignatureList->SignatureListSize    = (UINT32) SignatureListSize;
     SignatureList->SignatureSize        = (UINT32) (sizeof (EFI_SIGNATURE_DATA) - 1 + mImageDigestSize);
     CopyMem (&SignatureList->SignatureType, &mCertType, sizeof (EFI_GUID));
     Signature = (EFI_SIGNATURE_DATA *) ((UINT8 *) SignatureList + sizeof (EFI_SIGNATURE_LIST));
     CopyMem (Signature->SignatureData, mImageDigest, mImageDigestSize);
   }
 
-Done:
-  if (Status != EFI_SUCCESS) {
-    //
-    // Policy decides to defer or reject the image; add its information in image executable information table.
-    //
-    NameStr = ConvertDevicePathToText (File, FALSE, TRUE);
-    AddImageExeInfo (Action, NameStr, File, SignatureList, SignatureListSize);
-    if (NameStr != NULL) {
-      DEBUG((EFI_D_INFO, "The image doesn't pass verification: %s\n", NameStr));
-      FreePool(NameStr);
-    }
-    Status = EFI_SECURITY_VIOLATION;
+Failed:
+  //
+  // Policy decides to defer or reject the image; add its information in image executable information table.
+  //
+  NameStr = ConvertDevicePathToText (File, FALSE, TRUE);
+  AddImageExeInfo (Action, NameStr, File, SignatureList, SignatureListSize);
+  if (NameStr != NULL) {
+    DEBUG((EFI_D_INFO, "The image doesn't pass verification: %s\n", NameStr));
+    FreePool(NameStr);
   }
+  Status = EFI_SECURITY_VIOLATION;
 
   if (SignatureList != NULL) {
     FreePool (SignatureList);
   }
 
   return Status;
 }
 
 /**
   On Ready To Boot Services Event notification handler.
 
   Add the image execution information table if it is not in system configuration table.
 
   @param[in]  Event     Event whose notification function is being invoked
   @param[in]  Context   Pointer to the notification function's context
 
 **/
-- 
2.19.1.3.g30247aa5d201