Remove sysrq support to lift lockdown (rhbz 1800859)

1 files changed, 0 insertions, 287 deletions

diff --git a/lift-lockdown-sysrq.patch b/lift-lockdown-sysrq.patch
deleted file mode 100644
index b465143fb..000000000
--- a/lift-lockdown-sysrq.patch
+++ /dev/null
@@ -1,287 +0,0 @@
-From c2eb371cede78df9a47bf3a125aa9a45dd833da7 Mon Sep 17 00:00:00 2001
-From: Kyle McMartin <kyle@redhat.com>
-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 <kyle@redhat.com>
-Signed-off-by: David Howells <dhowells@redhat.com>
-cc: x86@kernel.org
-Signed-off-by: Jeremy Cline <jcline@redhat.com>
----
- 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 <linux/linkage.h>
- #include <asm/page_types.h>
- 
-+#define LOCKDOWN_LIFT_KEY 'x'
-+
- #ifdef __i386__
- 
- #include <linux/pfn.h>
-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 <linux/security.h>
- #include <linux/export.h>
- #include <linux/lsm_hooks.h>
-+#include <linux/sysrq.h>
-+#include <asm/setup.h>
- 
- 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
-