On 4/27/19 2:53 AM, Laszlo Ersek wrote:
> The entry point function of EnrollDefaultKeys finishes with a sanity
> check, verifying the values of the Secure Boot-related "control"
> variables. Add a diagram to explain why we expect the values we do.
>
> While at it, write comments on the rest of the entry point function.
>
> Cc: Anthony Perard <anthony.per...@citrix.com>
> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
> Cc: Jordan Justen <jordan.l.jus...@intel.com>
> Cc: Julien Grall <julien.gr...@arm.com>
> Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1747
> Signed-off-by: Laszlo Ersek <ler...@redhat.com>
> ---
> OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c | 54 ++++++++++++++++++++
> 1 file changed, 54 insertions(+)
>
> diff --git a/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c
> b/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c
> index 07297c631f38..9c4a0f06fb4d 100644
> --- a/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c
> +++ b/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c
> @@ -356,92 +356,146 @@ EFIAPI
> ShellAppMain (
> IN UINTN Argc,
> IN CHAR16 **Argv
> )
> {
> EFI_STATUS Status;
> SETTINGS Settings;
>
> + //
> + // If we're not in Setup Mode, we can't do anything.
> + //
> Status = GetSettings (&Settings);
> if (EFI_ERROR (Status)) {
> return 1;
> }
> PrintSettings (&Settings);
>
> if (Settings.SetupMode != 1) {
> AsciiPrint ("error: already in User Mode\n");
> return 1;
> }
>
> + //
> + // Enter Custom Mode so we can enroll PK, KEK, db, and dbx without
> signature
> + // checks on those variable writes.
> + //
> if (Settings.CustomMode != CUSTOM_SECURE_BOOT_MODE) {
> Settings.CustomMode = CUSTOM_SECURE_BOOT_MODE;
> Status = gRT->SetVariable (EFI_CUSTOM_MODE_NAME,
> &gEfiCustomModeEnableGuid,
> (EFI_VARIABLE_NON_VOLATILE |
> EFI_VARIABLE_BOOTSERVICE_ACCESS),
> sizeof Settings.CustomMode, &Settings.CustomMode);
> if (EFI_ERROR (Status)) {
> AsciiPrint ("error: SetVariable(\"%s\", %g): %r\n",
> EFI_CUSTOM_MODE_NAME,
> &gEfiCustomModeEnableGuid, Status);
> return 1;
> }
> }
>
> + //
> + // Enroll db.
> + //
> Status = EnrollListOfCerts (
> EFI_IMAGE_SECURITY_DATABASE,
> &gEfiImageSecurityDatabaseGuid,
> &gEfiCertX509Guid,
> mMicrosoftPca, mSizeOfMicrosoftPca, &gMicrosoftVendorGuid,
> mMicrosoftUefiCa, mSizeOfMicrosoftUefiCa, &gMicrosoftVendorGuid,
> NULL);
> if (EFI_ERROR (Status)) {
> return 1;
> }
>
> + //
> + // Enroll dbx.
> + //
> Status = EnrollListOfCerts (
> EFI_IMAGE_SECURITY_DATABASE1,
> &gEfiImageSecurityDatabaseGuid,
> &gEfiCertSha256Guid,
> mSha256OfDevNull, mSizeOfSha256OfDevNull, &gEfiCallerIdGuid,
> NULL);
> if (EFI_ERROR (Status)) {
> return 1;
> }
>
> + //
> + // Enroll KEK.
> + //
> Status = EnrollListOfCerts (
> EFI_KEY_EXCHANGE_KEY_NAME,
> &gEfiGlobalVariableGuid,
> &gEfiCertX509Guid,
> mRedHatPkKek1, mSizeOfRedHatPkKek1, &gEfiCallerIdGuid,
> mMicrosoftKek, mSizeOfMicrosoftKek, &gMicrosoftVendorGuid,
> NULL);
> if (EFI_ERROR (Status)) {
> return 1;
> }
>
> + //
> + // Enroll PK, leaving Setup Mode (entering User Mode) at once.
> + //
> Status = EnrollListOfCerts (
> EFI_PLATFORM_KEY_NAME,
> &gEfiGlobalVariableGuid,
> &gEfiCertX509Guid,
> mRedHatPkKek1, mSizeOfRedHatPkKek1, &gEfiGlobalVariableGuid,
> NULL);
> if (EFI_ERROR (Status)) {
> return 1;
> }
>
> + //
> + // Leave Custom Mode, so that updates to PK, KEK, db, and dbx require valid
> + // signatures.
> + //
> Settings.CustomMode = STANDARD_SECURE_BOOT_MODE;
> Status = gRT->SetVariable (EFI_CUSTOM_MODE_NAME, &gEfiCustomModeEnableGuid,
> EFI_VARIABLE_NON_VOLATILE |
> EFI_VARIABLE_BOOTSERVICE_ACCESS,
> sizeof Settings.CustomMode, &Settings.CustomMode);
> if (EFI_ERROR (Status)) {
> AsciiPrint ("error: SetVariable(\"%s\", %g): %r\n", EFI_CUSTOM_MODE_NAME,
> &gEfiCustomModeEnableGuid, Status);
> return 1;
> }
>
> + //
> + // Final sanity check:
> + //
> + // [SetupMode]
> + // (read-only, standardized by UEFI)
> + // / \_
> + // 0 1, default
> + // / \_
> + // PK enrolled no PK enrolled yet,
> + // (this is called "User Mode") PK enrollment
> possible
> + // |
> + // |
> + // [SecureBootEnable]
> + // (read-write, edk2-specific, boot service only)
> + // / \_
> + // 0 1, default
> + // / \_
> + // [SecureBoot]=0 [SecureBoot]=1
> + // (read-only, standardized by UEFI) (read-only, standardized by UEFI)
> + // images are not verified images are verified, platform is
> + // operating in Secure Boot mode
> + // |
> + // |
> + // [CustomMode]
> + // (read-write, edk2-specific, boot service only)
> + // / \_
> + // 0, default 1
> + // / \_
> + // PK, KEK, db, dbx PK, KEK, db, dbx
> + // updates are verified updates are not
> verified
> + //
Very helpful.
Reviewed-by: Philippe Mathieu-Daude <phi...@redhat.com>
> Status = GetSettings (&Settings);
> if (EFI_ERROR (Status)) {
> return 1;
> }
> PrintSettings (&Settings);
>
> if (Settings.SetupMode != 0 || Settings.SecureBoot != 1 ||
> Settings.SecureBootEnable != 1 || Settings.CustomMode != 0 ||
>
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