configfs: move CONFIGFS_MAGIC definition to magic.h

IMA shouldn't measure or appraise configfs, but currently does because
it's missing from the default exclusion policies. Move CONFIGFS_MAGIC to
magic.h to expose the file system's magic to IMA, as well as other userland
applications.

Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
Acked-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

fs/configfs/mount.c

@@ -9,6 +9,7 @@
  */
 
 #include <linux/fs.h>
+#include <linux/magic.h>
 #include <linux/module.h>
 #include <linux/mount.h>
 #include <linux/fs_context.h>
@@ -19,9 +20,6 @@
 #include <linux/configfs.h>
 #include "configfs_internal.h"
 
-/* Random magic number */
-#define CONFIGFS_MAGIC 0x62656570
-
 static struct vfsmount *configfs_mount = NULL;
 struct kmem_cache *configfs_dir_cachep;
 static int configfs_mnt_count = 0;

include/uapi/linux/magic.h

@@ -8,6 +8,7 @@
 #define AUTOFS_SUPER_MAGIC	0x0187
 #define CEPH_SUPER_MAGIC	0x00c36400
 #define CODA_SUPER_MAGIC	0x73757245
+#define CONFIGFS_MAGIC		0x62656570	/* some random number */
 #define CRAMFS_MAGIC		0x28cd3d45	/* some random number */
 #define CRAMFS_MAGIC_WEND	0x453dcd28	/* magic number with the wrong endianess */
 #define DEBUGFS_MAGIC          0x64626720