x86/ima: use correct identifier for SetupMode variable

commit ff5ac61ee83c13f516544d29847d28be093a40ee upstream.

The IMA arch code attempts to inspect the "SetupMode" EFI variable
by populating a variable called efi_SetupMode_name with the string
"SecureBoot" and passing that to the EFI GetVariable service, which
obviously does not yield the expected result.

Given that the string is only referenced a single time, let's get
rid of the intermediate variable, and pass the correct string as
an immediate argument. While at it, do the same for "SecureBoot".

Fixes: 399574c64eaf ("x86/ima: retry detecting secure boot mode")
Fixes: 980ef4d22a95 ("x86/ima: check EFI SetupMode too")
Cc: Matthew Garrett <mjg59@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: stable@vger.kernel.org # v5.3
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/ima_arch.c b/arch/x86/kernel/ima_arch.c
index 4d4f5d9..2305490 100644 (file)
--- a/arch/x86/kernel/ima_arch.c
+++ b/arch/x86/kernel/ima_arch.c
@@ -10,8 +10,6 @@ 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;
@@ -25,7 +23,7 @@ static enum efi_secureboot_mode get_sb_mode(void)
        }
 
        /* Get variable contents into buffer */
-       status = efi.get_variable(efi_SecureBoot_name, &efi_variable_guid,
+       status = efi.get_variable(L"SecureBoot", &efi_variable_guid,
                                  NULL, &size, &secboot);
        if (status == EFI_NOT_FOUND) {
                pr_info("ima: secureboot mode disabled\n");
@@ -38,7 +36,7 @@ static enum efi_secureboot_mode get_sb_mode(void)
        }
 
        size = sizeof(setupmode);
-       status = efi.get_variable(efi_SetupMode_name, &efi_variable_guid,
+       status = efi.get_variable(L"SetupMode", &efi_variable_guid,
                                  NULL, &size, &setupmode);
 
        if (status != EFI_SUCCESS)      /* ignore unknown SetupMode */