[PATCH 5.2 52/85] x86/ima: check EFI SetupMode too

Greg Kroah-Hartman
2019-09-18T06:29:29Z

From: Mimi Zohar <zohar@linux.ibm.com>

commit 980ef4d22a95a3cd84a9b8ffaa7b81b391d173c6 upstream.

Checking "SecureBoot" mode is not sufficient, also check "SetupMode".

Fixes: 399574c64eaf ("x86/ima: retry detecting secure boot mode")
Reported-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/ima_arch.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/ima_arch.c
+++ b/arch/x86/kernel/ima_arch.c
@@ -11,10 +11,11 @@ extern struct boot_params boot_params;
static enum efi_secureboot_mode get_sb_mode(void)
{
efi_char16_t efi_SecureBoot_name[] = L"SecureBoot";
+ efi_char16_t efi_SetupMode_name[] = L"SecureBoot";
efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
efi_status_t status;
unsigned long size;
- u8 secboot;
+ u8 secboot, setupmode;

size = sizeof(secboot);

@@ -36,7 +37,14 @@ static enum efi_secureboot_mode get_sb_m
return efi_secureboot_mode_unknown;
}

- if (secboot == 0) {
+ size = sizeof(setupmode);
+ status = efi.get_variable(efi_SetupMode_name, &efi_variable_guid,
+ NULL, &size, &setupmode);
+
+ if (status != EFI_SUCCESS) /* ignore unknown SetupMode */
+ setupmode = 0;
+
+ if (secboot == 0 || setupmode == 1) {
pr_info("ima: secureboot mode disabled\n");
return efi_secureboot_mode_disabled;
}