84 lines
2.4 KiB
C
84 lines
2.4 KiB
C
/*
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* Secure boot handling.
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*
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* Copyright (C) 2013,2014 Linaro Limited
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* Roy Franz <roy.franz@linaro.org
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* Copyright (C) 2013 Red Hat, Inc.
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* Mark Salter <msalter@redhat.com>
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*
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* This file is part of the Linux kernel, and is made available under the
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* terms of the GNU General Public License version 2.
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*/
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#include <linux/efi.h>
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#include <asm/efi.h>
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#include "efistub.h"
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/* BIOS variables */
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static const efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
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static const efi_char16_t efi_SecureBoot_name[] = L"SecureBoot";
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static const efi_char16_t efi_SetupMode_name[] = L"SetupMode";
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/* SHIM variables */
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static const efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
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static const efi_char16_t shim_MokSBState_name[] = L"MokSBState";
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#define get_efi_var(name, vendor, ...) \
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efi_call_runtime(get_variable, \
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(efi_char16_t *)(name), (efi_guid_t *)(vendor), \
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__VA_ARGS__);
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/*
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* Determine whether we're in secure boot mode.
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*
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* Please keep the logic in sync with
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* arch/x86/xen/efi.c:xen_efi_get_secureboot().
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*/
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enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table_arg)
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{
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u32 attr;
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u8 secboot, setupmode, moksbstate;
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unsigned long size;
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efi_status_t status;
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size = sizeof(secboot);
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status = get_efi_var(efi_SecureBoot_name, &efi_variable_guid,
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NULL, &size, &secboot);
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if (status == EFI_NOT_FOUND)
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return efi_secureboot_mode_disabled;
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if (status != EFI_SUCCESS)
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goto out_efi_err;
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size = sizeof(setupmode);
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status = get_efi_var(efi_SetupMode_name, &efi_variable_guid,
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NULL, &size, &setupmode);
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if (status != EFI_SUCCESS)
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goto out_efi_err;
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if (secboot == 0 || setupmode == 1)
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return efi_secureboot_mode_disabled;
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/*
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* See if a user has put the shim into insecure mode. If so, and if the
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* variable doesn't have the runtime attribute set, we might as well
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* honor that.
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*/
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size = sizeof(moksbstate);
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status = get_efi_var(shim_MokSBState_name, &shim_guid,
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&attr, &size, &moksbstate);
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/* If it fails, we don't care why. Default to secure */
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if (status != EFI_SUCCESS)
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goto secure_boot_enabled;
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if (!(attr & EFI_VARIABLE_RUNTIME_ACCESS) && moksbstate == 1)
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return efi_secureboot_mode_disabled;
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secure_boot_enabled:
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pr_efi(sys_table_arg, "UEFI Secure Boot is enabled.\n");
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return efi_secureboot_mode_enabled;
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out_efi_err:
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pr_efi_err(sys_table_arg, "Could not determine UEFI Secure Boot status.\n");
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return efi_secureboot_mode_unknown;
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}
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