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 <jcline@redhat.com>

1 files changed, 287 insertions, 0 deletions

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 <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
+