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x86/ima: retry detecting secure boot mode

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The secure boot mode may not be detected on boot for some reason (eg.
buggy firmware).  This patch attempts one more time to detect the
secure boot mode.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Mimi Zohar 2018-11-18 04:08:12 -05:00
parent 4264f27a08
commit 399574c64e
3 changed files with 47 additions and 3 deletions
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2
arch/x86/kernel/Makefile
View File

@ -151,4 +151,6 @@ ifeq ($(CONFIG_X86_64),y)
obj-y += vsmp_64.o
endif
ifdef CONFIG_EFI
obj-$(CONFIG_IMA) += ima_arch.o
endif

46
arch/x86/kernel/ima_arch.c
View File

@ -7,10 +7,52 @@
extern struct boot_params boot_params;
static enum efi_secureboot_mode get_sb_mode(void)
{
efi_char16_t efi_SecureBoot_name[] = L"SecureBoot";
efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
efi_status_t status;
unsigned long size;
u8 secboot;
size = sizeof(secboot);
/* Get variable contents into buffer */
status = efi.get_variable(efi_SecureBoot_name, &efi_variable_guid,
NULL, &size, &secboot);
if (status == EFI_NOT_FOUND) {
pr_info("ima: secureboot mode disabled\n");
return efi_secureboot_mode_disabled;
}
if (status != EFI_SUCCESS) {
pr_info("ima: secureboot mode unknown\n");
return efi_secureboot_mode_unknown;
}
if (secboot == 0) {
pr_info("ima: secureboot mode disabled\n");
return efi_secureboot_mode_disabled;
}
pr_info("ima: secureboot mode enabled\n");
return efi_secureboot_mode_enabled;
}
bool arch_ima_get_secureboot(void)
{
if (efi_enabled(EFI_BOOT) &&
(boot_params.secure_boot == efi_secureboot_mode_enabled))
static enum efi_secureboot_mode sb_mode;
static bool initialized;
if (!initialized && efi_enabled(EFI_BOOT)) {
sb_mode = boot_params.secure_boot;
if (sb_mode == efi_secureboot_mode_unset)
sb_mode = get_sb_mode();
initialized = true;
}
if (sb_mode == efi_secureboot_mode_enabled)
return true;
else
return false;

2
include/linux/ima.h
View File

@ -30,7 +30,7 @@ extern void ima_post_path_mknod(struct dentry *dentry);
extern void ima_add_kexec_buffer(struct kimage *image);
#endif
#ifdef CONFIG_X86
#if defined(CONFIG_X86) && defined(CONFIG_EFI)
extern bool arch_ima_get_secureboot(void);
extern const char * const *arch_get_ima_policy(void);
#else