OvmfPkg/VirtioFsDxe: call IsTimeValid() before EfiTimeToEpoch()

EmbeddedPkg/TimeBaseLib provides a verification function called
IsTimeValid(), for enforcing the UEFI spec requirements on an EFI_TIME
object.

When EFI_FILE_PROTOCOL.SetInfo() is called in order to update the
timestamps on the file, let's invoke IsTimeValid() first, before passing
the new EFI_FILE_INFO.{CreateTime,LastAccessTime,ModificationTime} values
to EfiTimeToEpoch().

This patch is not expected to make a practical difference, but it's better
to ascertain the preconditions of EfiTimeToEpoch() on the
EFI_FILE_PROTOCOL.SetInfo() caller. The FAT driver (EnhancedFatDxe) has a
similar check, namely in FatSetFileInfo() -> FatIsValidTime().

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20210107095051.22715-1-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

1 files changed, 16 insertions, 6 deletions

diff --git a/OvmfPkg/VirtioFsDxe/Helpers.c b/OvmfPkg/VirtioFsDxe/Helpers.c
index 443bbdc616..b81c04e0a4 100644
--- a/OvmfPkg/VirtioFsDxe/Helpers.c
+++ b/OvmfPkg/VirtioFsDxe/Helpers.c
@@ -2244,12 +2244,19 @@ VirtioFsGetFuseSizeUpdate (
                            since the Epoch). Otherwise, Mtime is not written

                            to.

 

-  @retval EFI_SUCCESS        Output parameters have been set successfully.

-

-  @retval EFI_ACCESS_DENIED  NewInfo requests changing both CreateTime and

-                             ModificationTime, but to values that differ from

-                             each other. The Virtio Filesystem device does not

-                             support this.

+  @retval EFI_SUCCESS            Output parameters have been set successfully.

+

+  @retval EFI_INVALID_PARAMETER  At least one of the CreateTime, LastAccessTime

+                                 and ModificationTime fields in NewInfo

+                                 represents an actual update relative to the

+                                 current state of the file (expressed in Info),

+                                 but does not satisfy the UEFI spec

+                                 requirements on EFI_TIME.

+

+  @retval EFI_ACCESS_DENIED      NewInfo requests changing both CreateTime and

+                                 ModificationTime, but to values that differ

+                                 from each other. The Virtio Filesystem device

+                                 does not support this.

 **/

 EFI_STATUS

 VirtioFsGetFuseTimeUpdates (

@@ -2285,6 +2292,9 @@ VirtioFsGetFuseTimeUpdates (
         CompareMem (NewTime[Idx], Time[Idx], sizeof (EFI_TIME)) == 0) {

       Change[Idx] = FALSE;

     } else {

+      if (!IsTimeValid (NewTime[Idx])) {

+        return EFI_INVALID_PARAMETER;

+      }

       Change[Idx] = TRUE;

       Seconds[Idx] = EfiTimeToEpoch (NewTime[Idx]);

     }