sysfs: Only accept read/write permissions for file attributes

For sysfs file attributes, only read and write permissions make sense. Mask provided attribute permissions accordingly and send a warning to the console if invalid permission bits are set. This patch is originally from Guenter [1] and includes the fixup explained in the thread, that is printing permissions in octal format and limiting the scope of attributes to SYSFS_PREALLOC | 0664. [1] https://lkml.org/lkml/2015/1/19/599 Signed-off-by: Vivien Didelot <[email protected]> Reviewed-by: Guenter Roeck <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
niw · Mar 25, 2015 · d8bf8c9 · d8bf8c9
1 parent da4759c
commit d8bf8c9
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
@@ -55,6 +55,12 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
 				if (!mode)
 					continue;
 			}
+
+			WARN(mode & ~(SYSFS_PREALLOC | 0664),
+			     "Attribute %s: Invalid permissions 0%o\n",
+			     (*attr)->name, mode);
+
+			mode &= SYSFS_PREALLOC | 0664;
 			error = sysfs_add_file_mode_ns(parent, *attr, false,
 						       mode, NULL);
 			if (unlikely(error))