Re: [PATCH] Pkcs7VerifyDxe: Don't allow Pkcs7Verify to install protocols twice.

["Kinney, Michael D" <michael.d.kinney@intel.com>]

Hi Peter,

If the protocol is already installed, you want to return an error
so the PE/COFF image for the driver will be unloaded.  Following the
example from Section 7.8 of UEFI Driver Writer's Guide an error code 
of EFI_ABORTED can be used for this case.

  Status = gBS->LocateProtocol (&gEfiPkcs7VerifyProtocolGuid, NULL, (VOID **)&Useless);
  if (!EFI_ERROR (Status)) {
    return EFI_ABORTED;
  }

Best regards,

Mike

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Peter Jones
> Sent: Thursday, September 29, 2016 8:59 AM
> To: edk2-devel@ml01.01.org
> Cc: Peter Jones <pjones@redhat.com>
> Subject: [edk2] [PATCH] Pkcs7VerifyDxe: Don't allow Pkcs7Verify to install protocols
> twice.
> 
> This patch makes Pkcs7VerifyDxe check that it has not already been
> installed before installing its protocols.  This prevents the case where
> loading it as an external driver (either manually, through Driver####
> variables, etc.) will refuse to add a second provider of the API.
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Peter Jones <pjones@redhat.com>
> ---
>  SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c
> b/SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c
> index 07fdf55..3389af4 100644
> --- a/SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c
> +++ b/SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c
> @@ -1030,8 +1030,16 @@ Pkcs7VerifyDriverEntry (
>    IN EFI_SYSTEM_TABLE    *SystemTable
>    )
>  {
> -  EFI_STATUS    Status;
> -  EFI_HANDLE    Handle;
> +  EFI_STATUS                Status;
> +  EFI_HANDLE                Handle;
> +  EFI_PKCS7_VERIFY_PROTOCOL Useless;
> +
> +  //
> +  // Avoid loading a second copy if this is built as an external module.
> +  //
> +  Status = gBS->LocateProtocol (&gEfiPkcs7VerifyProtocolGuid, NULL, (VOID **)
> &Useless);
> +  if (Status != EFI_NOT_FOUND)
> +	  return EFI_SUCCESS;> 
>    //
>    // Install UEFI Pkcs7 Verification Protocol
> --
> 2.10.0
> 
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