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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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ff5ac61ee8
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:399574c64e("x86/ima: retry detecting secure boot mode") Fixes:980ef4d22a("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>
94 lines
2.2 KiB
C
94 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Copyright (C) 2018 IBM Corporation
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*/
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#include <linux/efi.h>
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#include <linux/module.h>
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#include <linux/ima.h>
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extern struct boot_params boot_params;
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static enum efi_secureboot_mode get_sb_mode(void)
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{
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efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
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efi_status_t status;
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unsigned long size;
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u8 secboot, setupmode;
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size = sizeof(secboot);
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if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
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pr_info("ima: secureboot mode unknown, no efi\n");
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return efi_secureboot_mode_unknown;
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}
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/* Get variable contents into buffer */
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status = efi.get_variable(L"SecureBoot", &efi_variable_guid,
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NULL, &size, &secboot);
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if (status == EFI_NOT_FOUND) {
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pr_info("ima: secureboot mode disabled\n");
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return efi_secureboot_mode_disabled;
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}
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if (status != EFI_SUCCESS) {
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pr_info("ima: secureboot mode unknown\n");
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return efi_secureboot_mode_unknown;
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}
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size = sizeof(setupmode);
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status = efi.get_variable(L"SetupMode", &efi_variable_guid,
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NULL, &size, &setupmode);
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if (status != EFI_SUCCESS) /* ignore unknown SetupMode */
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setupmode = 0;
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if (secboot == 0 || setupmode == 1) {
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pr_info("ima: secureboot mode disabled\n");
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return efi_secureboot_mode_disabled;
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}
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pr_info("ima: secureboot mode enabled\n");
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return efi_secureboot_mode_enabled;
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}
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bool arch_ima_get_secureboot(void)
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{
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static enum efi_secureboot_mode sb_mode;
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static bool initialized;
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if (!initialized && efi_enabled(EFI_BOOT)) {
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sb_mode = boot_params.secure_boot;
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if (sb_mode == efi_secureboot_mode_unset)
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sb_mode = get_sb_mode();
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initialized = true;
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}
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if (sb_mode == efi_secureboot_mode_enabled)
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return true;
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else
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return false;
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}
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/* secureboot arch rules */
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static const char * const sb_arch_rules[] = {
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#if !IS_ENABLED(CONFIG_KEXEC_SIG)
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"appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig",
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#endif /* CONFIG_KEXEC_SIG */
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"measure func=KEXEC_KERNEL_CHECK",
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#if !IS_ENABLED(CONFIG_MODULE_SIG)
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"appraise func=MODULE_CHECK appraise_type=imasig",
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#endif
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"measure func=MODULE_CHECK",
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NULL
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};
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const char * const *arch_get_ima_policy(void)
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{
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if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot()) {
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if (IS_ENABLED(CONFIG_MODULE_SIG))
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set_module_sig_enforced();
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return sb_arch_rules;
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}
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return NULL;
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}
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