selinux: enable genfscon labeling for tracefs

In kernel version 4.1, tracefs was separated from debugfs into its
own filesystem. Prior to this split, files in
/sys/kernel/debug/tracing could be labeled during filesystem
creation using genfscon or later from userspace using setxattr. This
change re-enables support for genfscon labeling.
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -813,6 +813,7 @@ static int selinux_set_mnt_opts(struct super_block *sb,
 		sbsec->flags |= SE_SBPROC | SE_SBGENFS;
 
 	if (!strcmp(sb->s_type->name, "debugfs") ||
+	    !strcmp(sb->s_type->name, "tracefs") ||
 	    !strcmp(sb->s_type->name, "sysfs") ||
 	    !strcmp(sb->s_type->name, "pstore"))
 		sbsec->flags |= SE_SBGENFS;