projects / mirror_ubuntu-bionic-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 49b04f8a DH |
1 | /* Lock down the kernel |
| 2 | * | |
| 3 | * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved. | |
| 4 | * Written by David Howells (dhowells@redhat.com) | |
| 5 | * | |
| 6 | * This program is free software; you can redistribute it and/or | |
| 7 | * modify it under the terms of the GNU General Public Licence | |
| 8 | * as published by the Free Software Foundation; either version | |
| 9 | * 2 of the Licence, or (at your option) any later version. | |
| 10 | */ | |
| 11 | ||
| 12 | #include <linux/security.h> | |
| 13 | #include <linux/export.h> | |
| 531c25a3 | 14 | #include <linux/sysrq.h> |
| f80de0c3 | 15 | #include <linux/efi.h> |
| 531c25a3 | 16 | #include <asm/setup.h> |
| 49b04f8a | 17 | |
| 531c25a3 KM |
18 | #ifdef CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ |
| 19 | static __read_mostly bool kernel_locked_down; | |
| 20 | #else | |
| 49b04f8a | 21 | static __ro_after_init bool kernel_locked_down; |
| 531c25a3 | 22 | #endif |
| 49b04f8a DH |
23 | |
| 24 | /* | |
| 25 | * Put the kernel into lock-down mode. | |
| 26 | */ | |
| 27 | static void __init lock_kernel_down(const char *where) | |
| 28 | { | |
| 29 | if (!kernel_locked_down) { | |
| 30 | kernel_locked_down = true; | |
| 31 | pr_notice("Kernel is locked down from %s; see man kernel_lockdown.7\n", | |
| 32 | where); | |
| 33 | } | |
| 34 | } | |
| 35 | ||
| 36 | static int __init lockdown_param(char *ignored) | |
| 37 | { | |
| 38 | lock_kernel_down("command line"); | |
| 39 | return 0; | |
| 40 | } | |
| 41 | ||
| 42 | early_param("lockdown", lockdown_param); | |
| 43 | ||
| 44 | /* | |
| 45 | * Lock the kernel down from very early in the arch setup. This must happen | |
| 46 | * prior to things like ACPI being initialised. | |
| 47 | */ | |
| 48 | void __init init_lockdown(void) | |
| 49 | { | |
| 50 | #ifdef CONFIG_LOCK_DOWN_IN_EFI_SECURE_BOOT | |
| 51 | if (efi_enabled(EFI_SECURE_BOOT)) | |
| 52 | lock_kernel_down("EFI secure boot"); | |
| 53 | #endif | |
| 54 | } | |
| 55 | ||
| 56 | /** | |
| 57 | * kernel_is_locked_down - Find out if the kernel is locked down | |
| 58 | * @what: Tag to use in notice generated if lockdown is in effect | |
| 59 | */ | |
| 60 | bool __kernel_is_locked_down(const char *what, bool first) | |
| 61 | { | |
| 62 | if (what && first && kernel_locked_down) | |
| 63 | pr_notice("Lockdown: %s is restricted; see man kernel_lockdown.7\n", | |
| 64 | what); | |
| 65 | return kernel_locked_down; | |
| 66 | } | |
| 67 | EXPORT_SYMBOL(__kernel_is_locked_down); | |
| 531c25a3 KM |
68 | |
| 69 | #ifdef CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ | |
| 70 | ||
| 71 | /* | |
| 72 | * Take the kernel out of lockdown mode. | |
| 73 | */ | |
| 74 | static void lift_kernel_lockdown(void) | |
| 75 | { | |
| 76 | pr_notice("Lifting lockdown\n"); | |
| 77 | kernel_locked_down = false; | |
| 78 | } | |
| 79 | ||
| 80 | /* | |
| 81 | * Allow lockdown to be lifted by pressing something like SysRq+x (and not by | |
| 82 | * echoing the appropriate letter into the sysrq-trigger file). | |
| 83 | */ | |
| 84 | static void sysrq_handle_lockdown_lift(int key) | |
| 85 | { | |
| 86 | if (kernel_locked_down) | |
| 87 | lift_kernel_lockdown(); | |
| 88 | } | |
| 89 | ||
| 90 | static struct sysrq_key_op lockdown_lift_sysrq_op = { | |
| 91 | .handler = sysrq_handle_lockdown_lift, | |
| 92 | .help_msg = "unSB(x)", | |
| 93 | .action_msg = "Disabling Secure Boot restrictions", | |
| 94 | .enable_mask = SYSRQ_DISABLE_USERSPACE, | |
| 95 | }; | |
| 96 | ||
| 97 | static int __init lockdown_lift_sysrq(void) | |
| 98 | { | |
| 99 | if (kernel_locked_down) { | |
| 100 | lockdown_lift_sysrq_op.help_msg[5] = LOCKDOWN_LIFT_KEY; | |
| 101 | register_sysrq_key(LOCKDOWN_LIFT_KEY, &lockdown_lift_sysrq_op); | |
| 102 | } | |
| 103 | return 0; | |
| 104 | } | |
| 105 | ||
| 106 | late_initcall(lockdown_lift_sysrq); | |
| 107 | ||
| 108 | #endif /* CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ */ |