selinux: allow per-file labeling for cgroupfs

This patch allows genfscon per-file labeling for cgroupfs. For instance,
this allows to label the "release_agent" file within each
cgroup mount and limit writes to it.
Signed-off-by: Antonio Murdaca <amurdaca@redhat.com>
[PM: subject line and merge tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -815,7 +815,9 @@ static int selinux_set_mnt_opts(struct super_block *sb,
 	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"))
+	    !strcmp(sb->s_type->name, "pstore") ||
+	    !strcmp(sb->s_type->name, "cgroup") ||
+	    !strcmp(sb->s_type->name, "cgroup2"))
 		sbsec->flags |= SE_SBGENFS;
 
 	if (!sbsec->behavior) {