Re: [PATCH v2] SecurityPkg: Fix assert when setting key from eMMC/SD/USB

[Laszlo Ersek <lersek@redhat.com>]

On 07/11/18 17:44, Roman Bacik wrote:
> Hi Laszlo,
> 
> Thank you very much for your review and help. I would prefer the option 2b.

Great, thanks! Let's wait for the SecurityPkg maintainers then, to give
their R-b's for your patch. Chao Zhang, Jiewen, can you please comment?

>From my side, dependent on the pending commit message and patch
whitespace corrections (which I'm willing to implement myself, at push):

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thanks!
Laszlo


> Thanks,
> 
> Roman
> 
> On Wed, Jul 11, 2018 at 5:05 AM, Laszlo Ersek <lersek@redhat.com> wrote:
> 
>> Hi Roman,
>>
>> On 07/11/18 00:51, rbacik@gmail.com wrote:
>>> From: Roman Bacik <roman.bacik@broadcom.com>
>>>
>>> When secure boot is enabled, if one loads keys from a FAT formatted
>>> eMMC/SD/USB when trying to provision PK/KEK/DB keys via the menu,
>>> an assert in StrLen() occurs.
>>> This is because the filename starts on odd address, which is not a uint16
>>> aligned boundary: https://bugzilla.tianocore.org/show_bug.cgi?id=1003
>>>
>>> Cc: Chao Zhang <chao.b.zhang@intel.com>
>>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>>> Cc: Laszlo Ersek <lersek@redhat.com>
>>> Cc: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>> Signed-off-by: Roman Bacik <roman.bacik@broadcom.com>
>>> ---
>>>  SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigFileExplorer.c
>> | 13 +++++++++++--
>>>  1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> Thank you for sending a well-formed patch.
>>
>> I notice that you sent this email from <rbacik@gmail.com>, which is not
>> the same as the Signed-off-by line. I realize you posted from
>> <rbacik@gmail.com> for technical reasons, and it should be no problem.
>>
>> However, I *think* in such cases we usually request the following:
>>
>> - Using your broadcom.com email address, please respond to this patch
>> (not my present email, but your original git posting), keeping full
>> context, and just repeat your Signed-off-by line (referencing the
>> broadcom address).
>>
>> I'm CC'ing Jordan and Ard for confirmation -- I believe this is what
>> we've done in the past, in cases when submitters had to post their work
>> from private addresses due to company email issues.
>>
>> Technical comments below:
>>
>>> diff --git a/SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigFileExplorer.c
>> b/SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/
>> SecureBootConfigFileExplorer.c
>>> index 1b6f88804275..19b13a5569a6 100644
>>> --- a/SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/
>> SecureBootConfigFileExplorer.c
>>> +++ b/SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/
>> SecureBootConfigFileExplorer.c
>>> @@ -123,6 +123,8 @@ OpenFileByDevicePath(
>>>    EFI_FILE_PROTOCOL               *Handle1;
>>>    EFI_FILE_PROTOCOL               *Handle2;
>>>    EFI_HANDLE                      DeviceHandle;
>>> +  CHAR16                          *PathName;
>>> +  UINTN                           PathLength;
>>>
>>>    if ((FilePath == NULL || FileHandle == NULL)) {
>>>      return EFI_INVALID_PARAMETER;
>>> @@ -173,6 +175,11 @@ OpenFileByDevicePath(
>>>      //
>>>      Handle2  = Handle1;
>>>      Handle1 = NULL;
>>> +    PathLength = DevicePathNodeLength(*FilePath) -
>> sizeof(EFI_DEVICE_PATH_PROTOCOL);
>>> +    PathName = AllocateCopyPool(PathLength, ((FILEPATH_DEVICE_PATH*)*
>> FilePath)->PathName);
>>
>> (1) On both lines above, space characters are missing after:
>> DevicePathNodeLength, sizeof, and AllocateCopyPool. (Edk2 coding style.)
>> I think we can fix this up for you when we push the patch. (I'm willing
>> to help with that, but we need SecurityPkg maintainer review first.)
>>
>>
>>> +    if (PathName == NULL) {
>>> +      return EFI_OUT_OF_RESOURCES;
>>> +    }
>>
>> (2) I have now reviewed the original state of the function more
>> carefully, and, while the above "return" branch introduces a leak
>> *path*, it does not introduce a leak that doesn't already exist!
>>
>> In fact, the original function has multiple issues:
>>
>> - If the OpenVolume() call fails, "FileHandle" is set to NULL. That's
>> useless; the intent is obviously to set (*FileHandle) to NULL.
>>
>> - At the top of the "while" loop body, "Handle1" stands for an open
>> EFI_FILE_PROTOCOL. If the device path type check at the top of the loop
>> body returns EFI_INVALID_PARAMETER, then it (a) performs the same
>> useless assignment to "FileHandle" as described above, and (b) fails to
>> close "Handle1". This is why I say that the above EFI_OUT_OF_RESOURCES
>> branch introduces no new leak, just a new path to the existent leak.
>>
>> - The OpenFileByDevicePath() function is duplicated in the following
>> modules: "NetworkPkg/TlsAuthConfigDxe/TlsAuthConfigImpl.c", and
>> "MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskFileExplorer.c". With the
>> implication that the alignment issue you found affects all three drivers!
>>
>>
>> Roman, I realize this could be more than what you signed up for; so
>> please pick one:
>>
>> (2a) you could submit a patch series:
>>
>> * Write a patch that sets (*FilePath) to NULL right after the
>> (FileHandle==NULL) check, in preparation for failure, and removes all
>> the bogus FileHandle=NULL assignments.
>>
>> * Write another patch that plugs the leak when the device path type
>> check fails -- introduce a "CloseHandle1" label at the end of the
>> function, and jump to it when the devpath type check fails, so that we
>> close "Handle1". This patch should also invert the meanings of Handle2
>> and Handle1 -- the reassignment to Handle1 should only occur *after* we
>> successfully open Handle2. "Handle1" should *always* remain suitable for
>> closing through the "CloseHandle1" error path.
>>
>> * Include your current patch, for fixing the alignment issue.
>>
>> * Write another patch that moves the OpenFileByDevicePath() function to
>> UefiLib in MdePkg -- under the name EfiOpenFileByDevicePath() -- from
>> SecureBootConfigDxe.
>>
>> * write two more patches, namely for TlsAuthConfigDxe and RamDiskDxe, in
>> order to consume EfiOpenFileByDevicePath() from UefiLib. Both of those
>> modules already depend on UefiLib.
>>
>> (2b) Alternatively:
>>
>> * we can report a new TianoCore BZ about the issues I list above,
>>
>> * we can commit this patch of yours as-is, just additionally reference
>> the *new* BZ in the commit message, as "further known issues",
>>
>> * I can work on the rest of the issues.
>>
>>
>> If you pick (2b), then I can
>> - file the new BZ,
>> - update the commit message for you,
>> - update the patch for you, as described in (1),
>> - ACK this patch (as updated above),
>> - push the patch (if SecurityPkg maintainers agree),
>> - take on the new BZ as well.
>>
>> Thanks!
>> Laszlo
>>
>>>
>>>      //
>>>      // Try to test opening an existing file
>>> @@ -180,7 +187,7 @@ OpenFileByDevicePath(
>>>      Status = Handle2->Open (
>>>                            Handle2,
>>>                            &Handle1,
>>> -                          ((FILEPATH_DEVICE_PATH*)*FilePath)->PathName,
>>> +                          PathName,
>>>                            OpenMode &~EFI_FILE_MODE_CREATE,
>>>                            0
>>>                           );
>>> @@ -192,7 +199,7 @@ OpenFileByDevicePath(
>>>        Status = Handle2->Open (
>>>                              Handle2,
>>>                              &Handle1,
>>> -                            ((FILEPATH_DEVICE_PATH*)*
>> FilePath)->PathName,
>>> +                            PathName,
>>>                              OpenMode,
>>>                              Attributes
>>>                             );
>>> @@ -202,6 +209,8 @@ OpenFileByDevicePath(
>>>      //
>>>      Handle2->Close (Handle2);
>>>
>>> +    FreePool (PathName);
>>> +
>>>      if (EFI_ERROR(Status)) {
>>>        return (Status);
>>>      }
>>>
>>
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>