ACPI: Split out custom_method functionality into an own driver
With /sys/kernel/debug/acpi/custom_method root can write
to arbitrary memory and increase his priveleges, even if
these are restricted.
-> Make this an own debug .config option and warn about the
security issue in the config description.
-> Still keep acpi/debugfs.c which now only creates an empty
/sys/kernel/debug/acpi directory. There might be other
users of it later.
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: rui.zhang@intel.com
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/debugfs.c b/drivers/acpi/debugfs.c
index e7abc6e..182a9fc 100644
--- a/drivers/acpi/debugfs.c
+++ b/drivers/acpi/debugfs.c
@@ -3,9 +3,6 @@
*/
#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <acpi/acpi_drivers.h>
@@ -13,84 +10,9 @@
ACPI_MODULE_NAME("debugfs");
struct dentry *acpi_debugfs_dir;
-static struct dentry *cm_dentry;
-
-/* /sys/kernel/debug/acpi/custom_method */
-
-static ssize_t cm_write(struct file *file, const char __user * user_buf,
- size_t count, loff_t *ppos)
-{
- static char *buf;
- static u32 max_size;
- static u32 uncopied_bytes;
-
- struct acpi_table_header table;
- acpi_status status;
-
- if (!(*ppos)) {
- /* parse the table header to get the table length */
- if (count <= sizeof(struct acpi_table_header))
- return -EINVAL;
- if (copy_from_user(&table, user_buf,
- sizeof(struct acpi_table_header)))
- return -EFAULT;
- uncopied_bytes = max_size = table.length;
- buf = kzalloc(max_size, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
- }
-
- if (buf == NULL)
- return -EINVAL;
-
- if ((*ppos > max_size) ||
- (*ppos + count > max_size) ||
- (*ppos + count < count) ||
- (count > uncopied_bytes))
- return -EINVAL;
-
- if (copy_from_user(buf + (*ppos), user_buf, count)) {
- kfree(buf);
- buf = NULL;
- return -EFAULT;
- }
-
- uncopied_bytes -= count;
- *ppos += count;
-
- if (!uncopied_bytes) {
- status = acpi_install_method(buf);
- kfree(buf);
- buf = NULL;
- if (ACPI_FAILURE(status))
- return -EINVAL;
- add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
- }
-
- return count;
-}
-
-static const struct file_operations cm_fops = {
- .write = cm_write,
- .llseek = default_llseek,
-};
-
-static int __init acpi_custom_method_init(void)
-{
- if (!acpi_debugfs_dir)
- return -ENOENT;
-
- cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
- acpi_debugfs_dir, NULL, &cm_fops);
- if (!cm_dentry)
- return -ENODEV;
-
- return 0;
-}
+EXPORT_SYMBOL_GPL(acpi_debugfs_dir);
void __init acpi_debugfs_init(void)
{
acpi_debugfs_dir = debugfs_create_dir("acpi", NULL);
-
- acpi_custom_method_init();
}