OvmfPkg/VirtioFsDxe: handle the volume label in EFI_FILE_PROTOCOL.SetInfo

The least complicated third of EFI_FILE_PROTOCOL.SetInfo() is to handle
the EFI_FILE_SYSTEM_INFO and EFI_FILE_SYSTEM_VOLUME_LABEL setting
requests. Both of those can only change the volume label -- which the
Virtio Filesystem device does not support.

Verify the input for well-formedness, and report success only if the
volume label is being set to its current value.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20201216211125.19496-41-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

1 files changed, 225 insertions, 1 deletions

diff --git a/OvmfPkg/VirtioFsDxe/SimpleFsSetInfo.c b/OvmfPkg/VirtioFsDxe/SimpleFsSetInfo.c
index 200b7a1bcd..895b5c029a 100644
--- a/OvmfPkg/VirtioFsDxe/SimpleFsSetInfo.c
+++ b/OvmfPkg/VirtioFsDxe/SimpleFsSetInfo.c
@@ -6,8 +6,220 @@
   SPDX-License-Identifier: BSD-2-Clause-Patent

 **/

 

+#include <Guid/FileSystemInfo.h>            // gEfiFileSystemInfoGuid

+#include <Guid/FileSystemVolumeLabelInfo.h> // gEfiFileSystemVolumeLabelInfo...

+#include <Library/BaseLib.h>                // StrCmp()

+#include <Library/BaseMemoryLib.h>          // CompareGuid()

+

 #include "VirtioFsDxe.h"

 

+/**

+  Validate a buffer that the EFI_FILE_PROTOCOL.SetInfo() caller passes in for a

+  particular InformationType GUID.

+

+  The structure to be validated is supposed to end with a variable-length,

+  NUL-terminated CHAR16 Name string.

+

+  @param[in] SizeByProtocolCaller  The BufferSize parameter as provided by the

+                                   EFI_FILE_PROTOCOL.SetInfo() caller.

+

+  @param[in] MinimumStructSize     The minimum structure size that is required

+                                   for the given InformationType GUID,

+                                   including a single CHAR16 element from the

+                                   trailing Name field.

+

+  @param[in] IsSizeByInfoPresent   TRUE if and only if the expected structure

+                                   starts with a UINT64 Size field that reports

+                                   the actual structure size.

+

+  @param[in] Buffer                The Buffer parameter as provided by the

+                                   EFI_FILE_PROTOCOL.SetInfo() caller.

+

+  @retval EFI_SUCCESS            Validation successful, Buffer is well-formed.

+

+  @retval EFI_BAD_BUFFER_SIZE    The EFI_FILE_PROTOCOL.SetInfo()

+                                 caller provided a BufferSize that is smaller

+                                 than the minimum structure size required for

+                                 the given InformationType GUID.

+

+  @retval EFI_INVALID_PARAMETER  IsSizeByInfoPresent is TRUE, and the leading

+                                 UINT64 Size field does not match the

+                                 EFI_FILE_PROTOCOL.SetInfo() caller-provided

+                                 BufferSize.

+

+  @retval EFI_INVALID_PARAMETER  The trailing Name field does not consist of a

+                                 whole multiple of CHAR16 elements.

+

+  @retval EFI_INVALID_PARAMETER  The trailing Name field is not NUL-terminated.

+**/

+STATIC

+EFI_STATUS

+ValidateInfoStructure (

+  IN UINTN   SizeByProtocolCaller,

+  IN UINTN   MinimumStructSize,

+  IN BOOLEAN IsSizeByInfoPresent,

+  IN VOID    *Buffer

+  )

+{

+  UINTN  NameFieldByteOffset;

+  UINTN  NameFieldBytes;

+  UINTN  NameFieldChar16s;

+  CHAR16 *NameField;

+

+  //

+  // Make sure the internal function asking for validation passes in sane

+  // values.

+  //

+  ASSERT (MinimumStructSize >= sizeof (CHAR16));

+  NameFieldByteOffset = MinimumStructSize - sizeof (CHAR16);

+

+  if (IsSizeByInfoPresent) {

+    ASSERT (MinimumStructSize >= sizeof (UINT64) + sizeof (CHAR16));

+    ASSERT (NameFieldByteOffset >= sizeof (UINT64));

+  }

+

+  //

+  // Check whether the protocol caller provided enough bytes for the minimum

+  // size of this info structure.

+  //

+  if (SizeByProtocolCaller < MinimumStructSize) {

+    return EFI_BAD_BUFFER_SIZE;

+  }

+

+  //

+  // If the info structure starts with a UINT64 Size field, check if that

+  // agrees with the protocol caller-provided size.

+  //

+  if (IsSizeByInfoPresent) {

+    UINT64 *SizeByInfo;

+

+    SizeByInfo = Buffer;

+    if (*SizeByInfo != SizeByProtocolCaller) {

+      return EFI_INVALID_PARAMETER;

+    }

+  }

+

+  //

+  // The CHAR16 Name field at the end of the structure must have an even number

+  // of bytes.

+  //

+  // The subtraction below cannot underflow, and yields at least

+  // sizeof(CHAR16).

+  //

+  ASSERT (SizeByProtocolCaller >= NameFieldByteOffset);

+  NameFieldBytes = SizeByProtocolCaller - NameFieldByteOffset;

+  ASSERT (NameFieldBytes >= sizeof (CHAR16));

+  if (NameFieldBytes % sizeof (CHAR16) != 0) {

+    return EFI_INVALID_PARAMETER;

+  }

+

+  //

+  // The CHAR16 Name field at the end of the structure must be NUL-terminated.

+  //

+  NameFieldChar16s = NameFieldBytes / sizeof (CHAR16);

+  ASSERT (NameFieldChar16s >= 1);

+

+  NameField = (CHAR16 *)((UINT8 *)Buffer + NameFieldByteOffset);

+  if (NameField[NameFieldChar16s - 1] != L'\0') {

+    return EFI_INVALID_PARAMETER;

+  }

+

+  return EFI_SUCCESS;

+}

+

+/**

+  Process an EFI_FILE_SYSTEM_INFO setting request.

+**/

+STATIC

+EFI_STATUS

+SetFileSystemInfo (

+  IN EFI_FILE_PROTOCOL *This,

+  IN UINTN             BufferSize,

+  IN VOID              *Buffer

+  )

+{

+  VIRTIO_FS_FILE       *VirtioFsFile;

+  VIRTIO_FS            *VirtioFs;

+  EFI_STATUS           Status;

+  EFI_FILE_SYSTEM_INFO *FileSystemInfo;

+

+  VirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (This);

+  VirtioFs     = VirtioFsFile->OwnerFs;

+

+  //

+  // Validate if Buffer passes as EFI_FILE_SYSTEM_INFO.

+  //

+  Status = ValidateInfoStructure (

+             BufferSize,                       // SizeByProtocolCaller

+             OFFSET_OF (EFI_FILE_SYSTEM_INFO,

+               VolumeLabel) + sizeof (CHAR16), // MinimumStructSize

+             TRUE,                             // IsSizeByInfoPresent

+             Buffer

+             );

+  if (EFI_ERROR (Status)) {

+    return Status;

+  }

+  FileSystemInfo = Buffer;

+

+  //

+  // EFI_FILE_SYSTEM_INFO fields other than VolumeLabel cannot be changed, per

+  // spec.

+  //

+  // If the label is being changed to its current value, report success;

+  // otherwise, reject the request, as the Virtio Filesystem device does not

+  // support changing the label.

+  //

+  if (StrCmp (FileSystemInfo->VolumeLabel, VirtioFs->Label) == 0) {

+    return EFI_SUCCESS;

+  }

+  return EFI_WRITE_PROTECTED;

+}

+

+/**

+  Process an EFI_FILE_SYSTEM_VOLUME_LABEL setting request.

+**/

+STATIC

+EFI_STATUS

+SetFileSystemVolumeLabelInfo (

+  IN EFI_FILE_PROTOCOL *This,

+  IN UINTN             BufferSize,

+  IN VOID              *Buffer

+  )

+{

+  VIRTIO_FS_FILE               *VirtioFsFile;

+  VIRTIO_FS                    *VirtioFs;

+  EFI_STATUS                   Status;

+  EFI_FILE_SYSTEM_VOLUME_LABEL *FileSystemVolumeLabel;

+

+  VirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (This);

+  VirtioFs     = VirtioFsFile->OwnerFs;

+

+  //

+  // Validate if Buffer passes as EFI_FILE_SYSTEM_VOLUME_LABEL.

+  //

+  Status = ValidateInfoStructure (

+             BufferSize,                              // SizeByProtocolCaller

+             OFFSET_OF (EFI_FILE_SYSTEM_VOLUME_LABEL,

+               VolumeLabel) + sizeof (CHAR16),        // MinimumStructSize

+             FALSE,                                   // IsSizeByInfoPresent

+             Buffer

+             );

+  if (EFI_ERROR (Status)) {

+    return Status;

+  }

+  FileSystemVolumeLabel = Buffer;

+

+  //

+  // If the label is being changed to its current value, report success;

+  // otherwise, reject the request, as the Virtio Filesystem device does not

+  // support changing the label.

+  //

+  if (StrCmp (FileSystemVolumeLabel->VolumeLabel, VirtioFs->Label) == 0) {

+    return EFI_SUCCESS;

+  }

+  return EFI_WRITE_PROTECTED;

+}

+

 EFI_STATUS

 EFIAPI

 VirtioFsSimpleFileSetInfo (

@@ -17,5 +229,17 @@ VirtioFsSimpleFileSetInfo (
   IN VOID              *Buffer

   )

 {

-  return EFI_NO_MEDIA;

+  if (CompareGuid (InformationType, &gEfiFileInfoGuid)) {

+    return EFI_UNSUPPORTED;

+  }

+

+  if (CompareGuid (InformationType, &gEfiFileSystemInfoGuid)) {

+    return SetFileSystemInfo (This, BufferSize, Buffer);

+  }

+

+  if (CompareGuid (InformationType, &gEfiFileSystemVolumeLabelInfoIdGuid)) {

+    return SetFileSystemVolumeLabelInfo (This, BufferSize, Buffer);

+  }

+

+  return EFI_UNSUPPORTED;

 }