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56dc986a6b
With commit 099f26f22f ("integrity: machine keyring CA
configuration"), users are able to add custom IMA CA keys via
MOK. This allows users to sign their own IMA polices without
recompiling the kernel. For the sake of security, mandate signed IMA
policy when UEFI secure boot is enabled.
Note this change may affect existing users/tests i.e users won't be able
to load an unsigned IMA policy when the IMA architecture specific policy
is configured and UEFI secure boot is enabled.
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
78 lines
2 KiB
C
78 lines
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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#include <asm/efi.h>
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#ifndef arch_ima_efi_boot_mode
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#define arch_ima_efi_boot_mode efi_secureboot_mode_unset
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#endif
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static enum efi_secureboot_mode get_sb_mode(void)
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{
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enum efi_secureboot_mode mode;
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if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) {
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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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mode = efi_get_secureboot_mode(efi.get_variable);
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if (mode == efi_secureboot_mode_disabled)
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pr_info("ima: secureboot mode disabled\n");
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else if (mode == efi_secureboot_mode_unknown)
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pr_info("ima: secureboot mode unknown\n");
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else
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pr_info("ima: secureboot mode enabled\n");
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return mode;
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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 = arch_ima_efi_boot_mode;
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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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#if IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING) && IS_ENABLED(CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY)
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"appraise func=POLICY_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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if (IS_ENABLED(CONFIG_KEXEC_SIG))
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set_kexec_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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