SecurityPkg/SecureBootConfigDxe: require reset on all SB changes #137
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miczyg1
approved these changes
Jun 6, 2024
Enrolling or removing any signature should require a reset to avoid booting a system with some weird value of PCR-7. The PCR is extended on writes into SecureBoot-related variables (see SecureBootHook() in SecurityPkg/DxeImageVerificationLib) and then right before booting (in TcgDxe or Tcg2Dxe in OnReadyToBoot() handler), meaning that editing SecureBoot configuration and continuing boot process without a reset results in an unexpected value of PCR-7 even if the end result of changes is the same as it would be without any changes. Now reset is required in the following cases as well: * enrolling/deletion of a KEK signature * enrolling/deletion of a DB signature * enrolling/deletion of a DBX signature (one or all of them) * enrolling/deletion of a DBT signature Addition cases are handled in VFR while deletion options are checkboxes generated in C and that's where the flags get set (number of updated places is fewer than number of handled cases because functions are shared by menus). Signed-off-by: Sergii Dmytruk <[email protected]>
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Enrolling or removing any signature should require a reset to avoid booting a system with some weird value of PCR-7. The PCR is extended on writes into SecureBoot-related variables (see SecureBootHook() in SecurityPkg/DxeImageVerificationLib) and then right before booting (in TcgDxe or Tcg2Dxe in OnReadyToBoot() handler), meaning that editing SecureBoot configuration and continuing boot process without a reset results in an unexpected value of PCR-7 even if the end result of changes is the same as it would be without any changes.
Now reset is required in the following cases as well:
Addition cases are handled in VFR while deletion options are checkboxes generated in C and that's where the flags get set (number of updated places is fewer than number of handled cases because functions are shared by menus).