Commit 500de3dd authored by Thomas Renninger's avatar Thomas Renninger Committed by Matthew Garrett
Browse files

acpi ec_sys: Be more cautious about ec write access 



- Set Kconfig option default n
- Only allow root to read/write io file (sever bug!)
- Introduce write support module param -> default off
- Properly clean up if any debugfs files cannot be created

Signed-off-by: default avatarThomas Renninger <trenn@suse.de>
CC: mjg59@srcf.ucam.org
CC: platform-driver-x86@vger.kernel.org
CC: linux-acpi@vger.kernel.org
CC: astarikovskiy@suse.de
Signed-off-by: default avatarMatthew Garrett <mjg@redhat.com>
parent de4f1046

drivers/acpi/Kconfig

+8 −3
Original line number Diff line number Diff line
@@ -106,14 +106,19 @@ config ACPI_SYSFS_POWER 


config ACPI_EC_DEBUGFS

	tristate "EC read/write access through /sys/kernel/debug/ec"

	default y

	default n

	help

	  Say N to disable Embedded Controller /sys/kernel/debug interface



	  Be aware that using this interface can confuse your Embedded

	  Controller in a way that a normal reboot is not enough. You then

	  have to power of your system, and remove the laptop battery for

	  some seconds.

	  An Embedded Controller typically is available on laptops and reads

	  sensor values like battery state and temperature.

	  The kernel access the EC through ACPI parsed code provided by BIOS

	  tables.

	  The kernel accesses the EC through ACPI parsed code provided by BIOS

	  tables. This option allows to access the EC directly without ACPI

	  code being involved.

	  Thus this option is a debug option that helps to write ACPI drivers

	  and can be used to identify ACPI code or EC firmware bugs.

drivers/acpi/ec_sys.c

+24 −7
Original line number Diff line number Diff line
@@ -17,6 +17,11 @@ MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>"); 
MODULE_DESCRIPTION("ACPI EC sysfs access driver");

MODULE_LICENSE("GPL");



static bool write_support;

module_param(write_support, bool, 0644);

MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "

		 "be needed.");



#define EC_SPACE_SIZE 256



struct sysdev_class acpi_ec_sysdev_class = {
@@ -102,6 +107,8 @@ int acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count) 
{

	struct dentry *dev_dir;

	char name[64];

	mode_t mode = 0400;



	if (ec_device_count == 0) {

		acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);

		if (!acpi_ec_debugfs_dir)
@@ -111,17 +118,27 @@ int acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count) 
	sprintf(name, "ec%u", ec_device_count);

	dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir);

	if (!dev_dir) {

		if (ec_device_count == 0)

			debugfs_remove_recursive(acpi_ec_debugfs_dir);

		/* TBD: Proper cleanup for multiple ECs */

		if (ec_device_count != 0)

			goto error;

		return -ENOMEM;

	}



	debugfs_create_x32("gpe", 0444, dev_dir, (u32 *)&first_ec->gpe);

	debugfs_create_bool("use_global_lock", 0444, dev_dir,

			    (u32 *)&first_ec->global_lock);

	debugfs_create_file("io", 0666, dev_dir, ec, &acpi_ec_io_ops);

	if (!debugfs_create_x32("gpe", 0444, dev_dir, (u32 *)&first_ec->gpe))

		goto error;

	if (!debugfs_create_bool("use_global_lock", 0444, dev_dir,

				 (u32 *)&first_ec->global_lock))

		goto error;



	if (write_support)

		mode = 0600;

	if (!debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops))

		goto error;



	return 0;



error:

	debugfs_remove_recursive(acpi_ec_debugfs_dir);

	return -ENOMEM;

}



static int __init acpi_ec_sys_init(void)

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