linux/arch/x86/kernel/ima_arch.c
Ingo Molnar e9765680a3 EFI updates for v5.7:
This time, the set of changes for the EFI subsystem is much larger than
 usual. The main reasons are:
 - Get things cleaned up before EFI support for RISC-V arrives, which will
   increase the size of the validation matrix, and therefore the threshold to
   making drastic changes,
 - After years of defunct maintainership, the GRUB project has finally started
   to consider changes from the distros regarding UEFI boot, some of which are
   highly specific to the way x86 does UEFI secure boot and measured boot,
   based on knowledge of both shim internals and the layout of bootparams and
   the x86 setup header. Having this maintenance burden on other architectures
   (which don't need shim in the first place) is hard to justify, so instead,
   we are introducing a generic Linux/UEFI boot protocol.
 
 Summary of changes:
 - Boot time GDT handling changes (Arvind)
 - Simplify handling of EFI properties table on arm64
 - Generic EFI stub cleanups, to improve command line handling, file I/O,
   memory allocation, etc.
 - Introduce a generic initrd loading method based on calling back into
   the firmware, instead of relying on the x86 EFI handover protocol or
   device tree.
 - Introduce a mixed mode boot method that does not rely on the x86 EFI
   handover protocol either, and could potentially be adopted by other
   architectures (if another one ever surfaces where one execution mode
   is a superset of another)
 - Clean up the contents of struct efi, and move out everything that
   doesn't need to be stored there.
 - Incorporate support for UEFI spec v2.8A changes that permit firmware
   implementations to return EFI_UNSUPPORTED from UEFI runtime services at
   OS runtime, and expose a mask of which ones are supported or unsupported
   via a configuration table.
 - Various documentation updates and minor code cleanups (Heinrich)
 - Partial fix for the lack of by-VA cache maintenance in the decompressor
   on 32-bit ARM. Note that these patches were deliberately put at the
   beginning so they can be used as a stable branch that will be shared with
   a PR containing the complete fix, which I will send to the ARM tree.
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Merge tag 'efi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi into efi/core

Pull EFI updates for v5.7 from Ard Biesheuvel:

This time, the set of changes for the EFI subsystem is much larger than
usual. The main reasons are:

 - Get things cleaned up before EFI support for RISC-V arrives, which will
   increase the size of the validation matrix, and therefore the threshold to
   making drastic changes,

 - After years of defunct maintainership, the GRUB project has finally started
   to consider changes from the distros regarding UEFI boot, some of which are
   highly specific to the way x86 does UEFI secure boot and measured boot,
   based on knowledge of both shim internals and the layout of bootparams and
   the x86 setup header. Having this maintenance burden on other architectures
   (which don't need shim in the first place) is hard to justify, so instead,
   we are introducing a generic Linux/UEFI boot protocol.

Summary of changes:

 - Boot time GDT handling changes (Arvind)

 - Simplify handling of EFI properties table on arm64

 - Generic EFI stub cleanups, to improve command line handling, file I/O,
   memory allocation, etc.

 - Introduce a generic initrd loading method based on calling back into
   the firmware, instead of relying on the x86 EFI handover protocol or
   device tree.

 - Introduce a mixed mode boot method that does not rely on the x86 EFI
   handover protocol either, and could potentially be adopted by other
   architectures (if another one ever surfaces where one execution mode
   is a superset of another)

 - Clean up the contents of struct efi, and move out everything that
   doesn't need to be stored there.

 - Incorporate support for UEFI spec v2.8A changes that permit firmware
   implementations to return EFI_UNSUPPORTED from UEFI runtime services at
   OS runtime, and expose a mask of which ones are supported or unsupported
   via a configuration table.

 - Various documentation updates and minor code cleanups (Heinrich)

 - Partial fix for the lack of by-VA cache maintenance in the decompressor
   on 32-bit ARM. Note that these patches were deliberately put at the
   beginning so they can be used as a stable branch that will be shared with
   a PR containing the complete fix, which I will send to the ARM tree.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-02-26 15:21:22 +01:00

95 lines
2.3 KiB
C

/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Copyright (C) 2018 IBM Corporation
*/
#include <linux/efi.h>
#include <linux/module.h>
#include <linux/ima.h>
extern struct boot_params boot_params;
static enum efi_secureboot_mode get_sb_mode(void)
{
efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
efi_status_t status;
unsigned long size;
u8 secboot, setupmode;
size = sizeof(secboot);
if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) {
pr_info("ima: secureboot mode unknown, no efi\n");
return efi_secureboot_mode_unknown;
}
/* Get variable contents into buffer */
status = efi.get_variable(L"SecureBoot", &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;
}
size = sizeof(setupmode);
status = efi.get_variable(L"SetupMode", &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;
}
pr_info("ima: secureboot mode enabled\n");
return efi_secureboot_mode_enabled;
}
bool arch_ima_get_secureboot(void)
{
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;
}
/* secureboot arch rules */
static const char * const sb_arch_rules[] = {
#if !IS_ENABLED(CONFIG_KEXEC_SIG)
"appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig",
#endif /* CONFIG_KEXEC_SIG */
"measure func=KEXEC_KERNEL_CHECK",
#if !IS_ENABLED(CONFIG_MODULE_SIG)
"appraise func=MODULE_CHECK appraise_type=imasig",
#endif
"measure func=MODULE_CHECK",
NULL
};
const char * const *arch_get_ima_policy(void)
{
if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot()) {
if (IS_ENABLED(CONFIG_MODULE_SIG))
set_module_sig_enforced();
return sb_arch_rules;
}
return NULL;
}