From 5df4c5562f191b434edf57e8c92b176baad37cba Mon Sep 17 00:00:00 2001 From: Jeremy Cline Date: Wed, 2 Oct 2019 20:11:04 +0000 Subject: Rebase the lockdown sysrq patch to work with upstream Upstream finally merged the lockdown patches, adjust the SysRq patch to work with the upstreamed version. Signed-off-by: Jeremy Cline --- efi-lockdown.patch | 286 --------------------------------------------- kernel.spec | 14 +-- lift-lockdown-sysrq.patch | 287 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 294 insertions(+), 293 deletions(-) delete mode 100644 efi-lockdown.patch create mode 100644 lift-lockdown-sysrq.patch diff --git a/efi-lockdown.patch b/efi-lockdown.patch deleted file mode 100644 index be4f35e07..000000000 --- a/efi-lockdown.patch +++ /dev/null @@ -1,286 +0,0 @@ -From 4a84d19a10c31a363aa7d1f325bd212012263a98 Mon Sep 17 00:00:00 2001 -From: Kyle McMartin -Date: Mon, 9 Apr 2018 09:52:45 +0100 -Subject: [PATCH 28/29] Add a SysRq option to lift kernel lockdown - -Make an option to provide a sysrq key that will lift the kernel lockdown, -thereby allowing the running kernel image to be accessed and modified. - -On x86 this is triggered with SysRq+x, but this key may not be available on -all arches, so it is set by setting LOCKDOWN_LIFT_KEY in asm/setup.h. -Since this macro must be defined in an arch to be able to use this facility -for that arch, the Kconfig option is restricted to arches that support it. - -Signed-off-by: Kyle McMartin -Signed-off-by: David Howells -cc: x86@kernel.org ---- - arch/x86/include/asm/setup.h | 2 ++ - drivers/input/misc/uinput.c | 1 + - drivers/tty/sysrq.c | 19 ++++++++++----- - include/linux/input.h | 5 ++++ - include/linux/sysrq.h | 8 +++++- - kernel/debug/kdb/kdb_main.c | 2 +- - security/Kconfig | 10 ++++++++ - security/lock_down.c | 47 ++++++++++++++++++++++++++++++++++++ - 8 files changed, 86 insertions(+), 8 deletions(-) - -diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h -index ed8ec011a9fd..8daf633a5347 100644 ---- a/arch/x86/include/asm/setup.h -+++ b/arch/x86/include/asm/setup.h -@@ -9,6 +9,8 @@ - #include - #include - -+#define LOCKDOWN_LIFT_KEY 'x' -+ - #ifdef __i386__ - - #include -diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c -index 84051f20b18a..583ab2bc1916 100644 ---- a/drivers/input/misc/uinput.c -+++ b/drivers/input/misc/uinput.c -@@ -353,6 +353,7 @@ static int uinput_create_device(struct uinput_device *udev) - dev->flush = uinput_dev_flush; - } - -+ dev->flags |= INPUTDEV_FLAGS_SYNTHETIC; - dev->event = uinput_dev_event; - - input_set_drvdata(udev->dev, udev); -diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c -index 573b2055173c..7cc95a8bdf8d 100644 ---- a/drivers/tty/sysrq.c -+++ b/drivers/tty/sysrq.c -@@ -480,6 +480,7 @@ static struct sysrq_key_op *sysrq_key_table[36] = { - /* x: May be registered on mips for TLB dump */ - /* x: May be registered on ppc/powerpc for xmon */ - /* x: May be registered on sparc64 for global PMU dump */ -+ /* x: May be registered on x86_64 for disabling secure boot */ - NULL, /* x */ - /* y: May be registered on sparc64 for global register dump */ - NULL, /* y */ -@@ -523,7 +524,7 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) - sysrq_key_table[i] = op_p; - } - --void __handle_sysrq(int key, bool check_mask) -+void __handle_sysrq(int key, unsigned int from) - { - struct sysrq_key_op *op_p; - int orig_log_level; -@@ -546,11 +547,15 @@ void __handle_sysrq(int key, bool check_mask) - - op_p = __sysrq_get_key_op(key); - if (op_p) { -+ /* Ban synthetic events from some sysrq functionality */ -+ if ((from == SYSRQ_FROM_PROC || from == SYSRQ_FROM_SYNTHETIC) && -+ op_p->enable_mask & SYSRQ_DISABLE_USERSPACE) -+ printk("This sysrq operation is disabled from userspace.\n"); - /* - * Should we check for enabled operations (/proc/sysrq-trigger - * should not) and is the invoked operation enabled? - */ -- if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { -+ if (from == SYSRQ_FROM_KERNEL || sysrq_on_mask(op_p->enable_mask)) { - pr_info("%s\n", op_p->action_msg); - console_loglevel = orig_log_level; - op_p->handler(key); -@@ -585,7 +590,7 @@ void __handle_sysrq(int key, bool check_mask) - void handle_sysrq(int key) - { - if (sysrq_on()) -- __handle_sysrq(key, true); -+ __handle_sysrq(key, SYSRQ_FROM_KERNEL); - } - EXPORT_SYMBOL(handle_sysrq); - -@@ -665,7 +670,7 @@ static void sysrq_do_reset(struct timer_list *t) - static void sysrq_handle_reset_request(struct sysrq_state *state) - { - if (state->reset_requested) -- __handle_sysrq(sysrq_xlate[KEY_B], false); -+ __handle_sysrq(sysrq_xlate[KEY_B], SYSRQ_FROM_KERNEL); - - if (sysrq_reset_downtime_ms) - mod_timer(&state->keyreset_timer, -@@ -818,8 +823,10 @@ static bool sysrq_handle_keypress(struct sysrq_state *sysrq, - - default: - if (sysrq->active && value && value != 2) { -+ int from = sysrq->handle.dev->flags & INPUTDEV_FLAGS_SYNTHETIC ? -+ SYSRQ_FROM_SYNTHETIC : 0; - sysrq->need_reinject = false; -- __handle_sysrq(sysrq_xlate[code], true); -+ __handle_sysrq(sysrq_xlate[code], from); - } - break; - } -@@ -1102,7 +1109,7 @@ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, - - if (get_user(c, buf)) - return -EFAULT; -- __handle_sysrq(c, false); -+ __handle_sysrq(c, SYSRQ_FROM_PROC); - } - - return count; -diff --git a/include/linux/input.h b/include/linux/input.h -index 510e78558c10..7e7065b2f58a 100644 ---- a/include/linux/input.h -+++ b/include/linux/input.h -@@ -39,6 +39,7 @@ struct input_value { - * @phys: physical path to the device in the system hierarchy - * @uniq: unique identification code for the device (if device has it) - * @id: id of the device (struct input_id) -+ * @flags: input device flags (SYNTHETIC, etc.) - * @propbit: bitmap of device properties and quirks - * @evbit: bitmap of types of events supported by the device (EV_KEY, - * EV_REL, etc.) -@@ -121,6 +122,8 @@ struct input_dev { - const char *uniq; - struct input_id id; - -+ unsigned int flags; -+ - unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)]; - - unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; -@@ -187,6 +190,8 @@ struct input_dev { - }; - #define to_input_dev(d) container_of(d, struct input_dev, dev) - -+#define INPUTDEV_FLAGS_SYNTHETIC 0x000000001 -+ - /* - * Verify that we are in sync with input_device_id mod_devicetable.h #defines - */ -diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h -index 8c71874e8485..7de1f08b60a9 100644 ---- a/include/linux/sysrq.h -+++ b/include/linux/sysrq.h -@@ -29,6 +29,8 @@ - #define SYSRQ_ENABLE_BOOT 0x0080 - #define SYSRQ_ENABLE_RTNICE 0x0100 - -+#define SYSRQ_DISABLE_USERSPACE 0x00010000 -+ - struct sysrq_key_op { - void (*handler)(int); - char *help_msg; -@@ -43,8 +45,12 @@ struct sysrq_key_op { - * are available -- else NULL's). - */ - -+#define SYSRQ_FROM_KERNEL 0x0001 -+#define SYSRQ_FROM_PROC 0x0002 -+#define SYSRQ_FROM_SYNTHETIC 0x0004 -+ - void handle_sysrq(int key); --void __handle_sysrq(int key, bool check_mask); -+void __handle_sysrq(int key, unsigned int from); - int register_sysrq_key(int key, struct sysrq_key_op *op); - int unregister_sysrq_key(int key, struct sysrq_key_op *op); - struct sysrq_key_op *__sysrq_get_key_op(int key); -diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c -index 9ecfa37c7fbf..902b7785d7dc 100644 ---- a/kernel/debug/kdb/kdb_main.c -+++ b/kernel/debug/kdb/kdb_main.c -@@ -1981,7 +1981,7 @@ static int kdb_sr(int argc, const char **argv) - return KDB_ARGCOUNT; - - kdb_trap_printk++; -- __handle_sysrq(*argv[1], check_mask); -+ __handle_sysrq(*argv[1], check_mask ? SYSRQ_FROM_KERNEL : 0); - kdb_trap_printk--; - - return 0; -diff --git a/security/Kconfig b/security/Kconfig -index 720cf9dee2b4..fe08b674bfce 100644 ---- a/security/Kconfig -+++ b/security/Kconfig -@@ -245,6 +245,16 @@ config LOCK_DOWN_KERNEL_FORCE - help - Enable the kernel lock down functionality automatically at boot. - -+config ALLOW_LOCKDOWN_LIFT_BY_SYSRQ -+ bool "Allow the kernel lockdown to be lifted by SysRq" -+ depends on LOCK_DOWN_KERNEL -+ depends on !LOCK_DOWN_KERNEL_FORCE -+ depends on MAGIC_SYSRQ -+ depends on X86 -+ help -+ Allow the lockdown on a kernel to be lifted, by pressing a SysRq key -+ combination on a wired keyboard. On x86, this is SysRq+x. -+ - source "security/selinux/Kconfig" - source "security/smack/Kconfig" - source "security/tomoyo/Kconfig" -diff --git a/security/lock_down.c b/security/lock_down.c -index ee00ca2677e7..d68dff872ced 100644 ---- a/security/lock_down.c -+++ b/security/lock_down.c -@@ -12,8 +12,14 @@ - - #include - #include -+#include -+#include - -+#ifdef CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ -+static __read_mostly bool kernel_locked_down; -+#else - static __ro_after_init bool kernel_locked_down; -+#endif - - /* - * Put the kernel into lock-down mode. -@@ -58,3 +64,44 @@ bool __kernel_is_locked_down(const char *what, bool first) - return kernel_locked_down; - } - EXPORT_SYMBOL(__kernel_is_locked_down); -+ -+#ifdef CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ -+ -+/* -+ * Take the kernel out of lockdown mode. -+ */ -+static void lift_kernel_lockdown(void) -+{ -+ pr_notice("Lifting lockdown\n"); -+ kernel_locked_down = false; -+} -+ -+/* -+ * Allow lockdown to be lifted by pressing something like SysRq+x (and not by -+ * echoing the appropriate letter into the sysrq-trigger file). -+ */ -+static void sysrq_handle_lockdown_lift(int key) -+{ -+ if (kernel_locked_down) -+ lift_kernel_lockdown(); -+} -+ -+static struct sysrq_key_op lockdown_lift_sysrq_op = { -+ .handler = sysrq_handle_lockdown_lift, -+ .help_msg = "unSB(x)", -+ .action_msg = "Disabling Secure Boot restrictions", -+ .enable_mask = SYSRQ_DISABLE_USERSPACE, -+}; -+ -+static int __init lockdown_lift_sysrq(void) -+{ -+ if (kernel_locked_down) { -+ lockdown_lift_sysrq_op.help_msg[5] = LOCKDOWN_LIFT_KEY; -+ register_sysrq_key(LOCKDOWN_LIFT_KEY, &lockdown_lift_sysrq_op); -+ } -+ return 0; -+} -+ -+late_initcall(lockdown_lift_sysrq); -+ -+#endif /* CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ */ --- -2.21.0 diff --git a/kernel.spec b/kernel.spec index 32b6f8985..81fb25d8e 100644 --- a/kernel.spec +++ b/kernel.spec @@ -499,16 +499,16 @@ Patch122: Input-synaptics-pin-3-touches-when-the-firmware-repo.patch # 200 - x86 / secureboot -# Patch201: efi-lockdown.patch - # bz 1497559 - Make kernel MODSIGN code not error on missing variables -Patch207: 0001-Make-get_cert_list-not-complain-about-cert-lists-tha.patch -Patch208: 0002-Add-efi_status_to_str-and-rework-efi_status_to_err.patch -Patch209: 0003-Make-get_cert_list-use-efi_status_to_str-to-print-er.patch +Patch200: 0001-Make-get_cert_list-not-complain-about-cert-lists-tha.patch +Patch201: 0002-Add-efi_status_to_str-and-rework-efi_status_to_err.patch +Patch202: 0003-Make-get_cert_list-use-efi_status_to_str-to-print-er.patch + +Patch203: disable-i8042-check-on-apple-mac.patch -Patch210: disable-i8042-check-on-apple-mac.patch +Patch204: efi-secureboot.patch -Patch212: efi-secureboot.patch +Patch205: lift-lockdown-sysrq.patch # 300 - ARM patches Patch300: arm64-Add-option-of-13-for-FORCE_MAX_ZONEORDER.patch diff --git a/lift-lockdown-sysrq.patch b/lift-lockdown-sysrq.patch new file mode 100644 index 000000000..b465143fb --- /dev/null +++ b/lift-lockdown-sysrq.patch @@ -0,0 +1,287 @@ +From c2eb371cede78df9a47bf3a125aa9a45dd833da7 Mon Sep 17 00:00:00 2001 +From: Kyle McMartin +Date: Mon, 9 Apr 2018 09:52:45 +0100 +Subject: [PATCH] Add a SysRq option to lift kernel lockdown + +Make an option to provide a sysrq key that will lift the kernel lockdown, +thereby allowing the running kernel image to be accessed and modified. + +On x86 this is triggered with SysRq+x, but this key may not be available on +all arches, so it is set by setting LOCKDOWN_LIFT_KEY in asm/setup.h. +Since this macro must be defined in an arch to be able to use this facility +for that arch, the Kconfig option is restricted to arches that support it. + +Signed-off-by: Kyle McMartin +Signed-off-by: David Howells +cc: x86@kernel.org +Signed-off-by: Jeremy Cline +--- + arch/x86/include/asm/setup.h | 2 ++ + drivers/input/misc/uinput.c | 1 + + drivers/tty/sysrq.c | 27 +++++++++++++--------- + include/linux/input.h | 5 +++++ + include/linux/sysrq.h | 8 ++++++- + kernel/debug/kdb/kdb_main.c | 2 +- + security/lockdown/Kconfig | 11 +++++++++ + security/lockdown/lockdown.c | 43 ++++++++++++++++++++++++++++++++++++ + 8 files changed, 87 insertions(+), 12 deletions(-) + +diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h +index ed8ec011a9fd..8daf633a5347 100644 +--- a/arch/x86/include/asm/setup.h ++++ b/arch/x86/include/asm/setup.h +@@ -9,6 +9,8 @@ + #include + #include + ++#define LOCKDOWN_LIFT_KEY 'x' ++ + #ifdef __i386__ + + #include +diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c +index 84051f20b18a..583ab2bc1916 100644 +--- a/drivers/input/misc/uinput.c ++++ b/drivers/input/misc/uinput.c +@@ -353,6 +353,7 @@ static int uinput_create_device(struct uinput_device *udev) + dev->flush = uinput_dev_flush; + } + ++ dev->flags |= INPUTDEV_FLAGS_SYNTHETIC; + dev->event = uinput_dev_event; + + input_set_drvdata(udev->dev, udev); +diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c +index 573b2055173c..99082faafc44 100644 +--- a/drivers/tty/sysrq.c ++++ b/drivers/tty/sysrq.c +@@ -480,6 +480,7 @@ static struct sysrq_key_op *sysrq_key_table[36] = { + /* x: May be registered on mips for TLB dump */ + /* x: May be registered on ppc/powerpc for xmon */ + /* x: May be registered on sparc64 for global PMU dump */ ++ /* x: May be registered on x86_64 for disabling secure boot */ + NULL, /* x */ + /* y: May be registered on sparc64 for global register dump */ + NULL, /* y */ +@@ -523,7 +524,7 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) + sysrq_key_table[i] = op_p; + } + +-void __handle_sysrq(int key, bool check_mask) ++void __handle_sysrq(int key, unsigned int from) + { + struct sysrq_key_op *op_p; + int orig_log_level; +@@ -546,11 +547,15 @@ void __handle_sysrq(int key, bool check_mask) + + op_p = __sysrq_get_key_op(key); + if (op_p) { +- /* +- * Should we check for enabled operations (/proc/sysrq-trigger +- * should not) and is the invoked operation enabled? +- */ +- if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { ++ /* Ban synthetic events from some sysrq functionality */ ++ if ((from == SYSRQ_FROM_PROC || from == SYSRQ_FROM_SYNTHETIC) && ++ op_p->enable_mask & SYSRQ_DISABLE_USERSPACE) { ++ printk("This sysrq operation is disabled from userspace.\n"); ++ } else if (from == SYSRQ_FROM_KERNEL || sysrq_on_mask(op_p->enable_mask)) { ++ /* ++ * Should we check for enabled operations (/proc/sysrq-trigger ++ * should not) and is the invoked operation enabled? ++ */ + pr_info("%s\n", op_p->action_msg); + console_loglevel = orig_log_level; + op_p->handler(key); +@@ -585,7 +590,7 @@ void __handle_sysrq(int key, bool check_mask) + void handle_sysrq(int key) + { + if (sysrq_on()) +- __handle_sysrq(key, true); ++ __handle_sysrq(key, SYSRQ_FROM_KERNEL); + } + EXPORT_SYMBOL(handle_sysrq); + +@@ -665,7 +670,7 @@ static void sysrq_do_reset(struct timer_list *t) + static void sysrq_handle_reset_request(struct sysrq_state *state) + { + if (state->reset_requested) +- __handle_sysrq(sysrq_xlate[KEY_B], false); ++ __handle_sysrq(sysrq_xlate[KEY_B], SYSRQ_FROM_KERNEL); + + if (sysrq_reset_downtime_ms) + mod_timer(&state->keyreset_timer, +@@ -818,8 +823,10 @@ static bool sysrq_handle_keypress(struct sysrq_state *sysrq, + + default: + if (sysrq->active && value && value != 2) { ++ int from = sysrq->handle.dev->flags & INPUTDEV_FLAGS_SYNTHETIC ? ++ SYSRQ_FROM_SYNTHETIC : 0; + sysrq->need_reinject = false; +- __handle_sysrq(sysrq_xlate[code], true); ++ __handle_sysrq(sysrq_xlate[code], from); + } + break; + } +@@ -1102,7 +1109,7 @@ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, + + if (get_user(c, buf)) + return -EFAULT; +- __handle_sysrq(c, false); ++ __handle_sysrq(c, SYSRQ_FROM_PROC); + } + + return count; +diff --git a/include/linux/input.h b/include/linux/input.h +index 94f277cd806a..8539afa2c001 100644 +--- a/include/linux/input.h ++++ b/include/linux/input.h +@@ -48,6 +48,7 @@ enum input_clock_type { + * @phys: physical path to the device in the system hierarchy + * @uniq: unique identification code for the device (if device has it) + * @id: id of the device (struct input_id) ++ * @flags: input device flags (SYNTHETIC, etc.) + * @propbit: bitmap of device properties and quirks + * @evbit: bitmap of types of events supported by the device (EV_KEY, + * EV_REL, etc.) +@@ -134,6 +135,8 @@ struct input_dev { + const char *uniq; + struct input_id id; + ++ unsigned int flags; ++ + unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)]; + + unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; +@@ -204,6 +207,8 @@ struct input_dev { + }; + #define to_input_dev(d) container_of(d, struct input_dev, dev) + ++#define INPUTDEV_FLAGS_SYNTHETIC 0x000000001 ++ + /* + * Verify that we are in sync with input_device_id mod_devicetable.h #defines + */ +diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h +index 8c71874e8485..7de1f08b60a9 100644 +--- a/include/linux/sysrq.h ++++ b/include/linux/sysrq.h +@@ -29,6 +29,8 @@ + #define SYSRQ_ENABLE_BOOT 0x0080 + #define SYSRQ_ENABLE_RTNICE 0x0100 + ++#define SYSRQ_DISABLE_USERSPACE 0x00010000 ++ + struct sysrq_key_op { + void (*handler)(int); + char *help_msg; +@@ -43,8 +45,12 @@ struct sysrq_key_op { + * are available -- else NULL's). + */ + ++#define SYSRQ_FROM_KERNEL 0x0001 ++#define SYSRQ_FROM_PROC 0x0002 ++#define SYSRQ_FROM_SYNTHETIC 0x0004 ++ + void handle_sysrq(int key); +-void __handle_sysrq(int key, bool check_mask); ++void __handle_sysrq(int key, unsigned int from); + int register_sysrq_key(int key, struct sysrq_key_op *op); + int unregister_sysrq_key(int key, struct sysrq_key_op *op); + struct sysrq_key_op *__sysrq_get_key_op(int key); +diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c +index 4567fe998c30..d05142ef44c4 100644 +--- a/kernel/debug/kdb/kdb_main.c ++++ b/kernel/debug/kdb/kdb_main.c +@@ -1981,7 +1981,7 @@ static int kdb_sr(int argc, const char **argv) + return KDB_ARGCOUNT; + + kdb_trap_printk++; +- __handle_sysrq(*argv[1], check_mask); ++ __handle_sysrq(*argv[1], check_mask ? SYSRQ_FROM_KERNEL : 0); + kdb_trap_printk--; + + return 0; +diff --git a/security/lockdown/Kconfig b/security/lockdown/Kconfig +index e84ddf484010..20e979178e1c 100644 +--- a/security/lockdown/Kconfig ++++ b/security/lockdown/Kconfig +@@ -45,3 +45,14 @@ config LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY + disabled. + + endchoice ++ ++config ALLOW_LOCKDOWN_LIFT_BY_SYSRQ ++ bool "Allow the kernel lockdown to be lifted by SysRq" ++ depends on SECURITY_LOCKDOWN_LSM ++ depends on !LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY ++ depends on !LOCK_DOWN_KERNEL_FORCE_INTEGRITY ++ depends on MAGIC_SYSRQ ++ depends on X86 ++ help ++ Allow setting the lockdown mode to "none" by pressing a SysRq key ++ combination on a wired keyboard. On x86, this is SysRq+x +diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c +index 8a10b43daf74..df4662257309 100644 +--- a/security/lockdown/lockdown.c ++++ b/security/lockdown/lockdown.c +@@ -13,6 +13,8 @@ + #include + #include + #include ++#include ++#include + + static enum lockdown_reason kernel_locked_down; + +@@ -179,6 +181,47 @@ static int __init lockdown_secfs_init(void) + return PTR_ERR_OR_ZERO(dentry); + } + ++#ifdef CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ ++ ++/* ++ * Take the kernel out of lockdown mode. ++ */ ++static void lift_kernel_lockdown(void) ++{ ++ pr_notice("Lifting lockdown\n"); ++ kernel_locked_down = LOCKDOWN_NONE; ++} ++ ++/* ++ * Allow lockdown to be lifted by pressing something like SysRq+x (and not by ++ * echoing the appropriate letter into the sysrq-trigger file). ++ */ ++static void sysrq_handle_lockdown_lift(int key) ++{ ++ if (kernel_locked_down) ++ lift_kernel_lockdown(); ++} ++ ++static struct sysrq_key_op lockdown_lift_sysrq_op = { ++ .handler = sysrq_handle_lockdown_lift, ++ .help_msg = "unSB(x)", ++ .action_msg = "Disabling Secure Boot restrictions", ++ .enable_mask = SYSRQ_DISABLE_USERSPACE, ++}; ++ ++static int __init lockdown_lift_sysrq(void) ++{ ++ if (kernel_locked_down) { ++ lockdown_lift_sysrq_op.help_msg[5] = LOCKDOWN_LIFT_KEY; ++ register_sysrq_key(LOCKDOWN_LIFT_KEY, &lockdown_lift_sysrq_op); ++ } ++ return 0; ++} ++ ++late_initcall(lockdown_lift_sysrq); ++ ++#endif /* CONFIG_ALLOW_LOCKDOWN_LIFT_BY_SYSRQ */ ++ + core_initcall(lockdown_secfs_init); + + #ifdef CONFIG_SECURITY_LOCKDOWN_LSM_EARLY +-- +2.21.0 + -- cgit