The driver exposes EFI runtime services to user-space through an IOCTL interface, calling the EFI services function pointers directly without using the efivar API. Disallow access to the /dev/efi_test character device when the kernel is locked down to prevent arbitrary user-space to call EFI runtime services. Also require CAP_SYS_ADMIN to open the chardev to prevent unprivileged users to call the EFI runtime services, instead of just relying on the chardev file mode bits for this. The main user of this driver is the fwts [0] tool that already checks if the effective user ID is 0 and fails otherwise. So this change shouldn't cause any regression to this tool. [0]: https://wiki.ubuntu.com/FirmwareTestSuite/Reference/uefivarinfo
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| @@ -105,6 +105,7 @@ enum lockdown_reason { · 104 unmodified lines | ||
| 105 | 105 | LOCKDOWN_NONE, |
| 106 | 106 | LOCKDOWN_MODULE_SIGNATURE, |
| 107 | 107 | LOCKDOWN_DEV_MEM, |
| 108 | + LOCKDOWN_EFI_TEST, | |
| 108 | 109 | LOCKDOWN_KEXEC, |
| 109 | 110 | LOCKDOWN_HIBERNATION, |
| 110 | 111 | LOCKDOWN_PCI_ACCESS, |