properly handle multiple messages in selinux_netlink_send()

static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)

{

	int err = 0;

	u32 perm;

	int rc = 0;

	unsigned int msg_len;

	unsigned int data_len = skb->len;

	unsigned char *data = skb->data;

	struct nlmsghdr *nlh;

	struct sk_security_struct *sksec = sk->sk_security;

	u16 sclass = sksec->sclass;

	u32 perm;

	if (skb->len < NLMSG_HDRLEN) {

		err = -EINVAL;

		goto out;

	}

	nlh = nlmsg_hdr(skb);

	while (data_len >= nlmsg_total_size(0)) {

		nlh = (struct nlmsghdr *)data;

	err = selinux_nlmsg_lookup(sksec->sclass, nlh->nlmsg_type, &perm);

	if (err) {

		if (err == -EINVAL) {

		/* NOTE: the nlmsg_len field isn't reliably set by some netlink

		 *       users which means we can't reject skb's with bogus

		 *       length fields; our solution is to follow what

		 *       netlink_rcv_skb() does and simply skip processing at

		 *       messages with length fields that are clearly junk

		 */

		if (nlh->nlmsg_len < NLMSG_HDRLEN || nlh->nlmsg_len > data_len)

			return 0;

		rc = selinux_nlmsg_lookup(sclass, nlh->nlmsg_type, &perm);

		if (rc == 0) {

			rc = sock_has_perm(sk, perm);

			if (rc)

				return rc;

		} else if (rc == -EINVAL) {

			/* -EINVAL is a missing msg/perm mapping */

			pr_warn_ratelimited("SELinux: unrecognized netlink"

				" message: protocol=%hu nlmsg_type=%hu sclass=%s"

			       " pig=%d comm=%s\n",

				" pid=%d comm=%s\n",

				sk->sk_protocol, nlh->nlmsg_type,

			       secclass_map[sksec->sclass - 1].name,

				secclass_map[sclass - 1].name,

				task_pid_nr(current), current->comm);

			if (!enforcing_enabled(&selinux_state) ||

			    security_get_allow_unknown(&selinux_state))

				err = 0;

			if (enforcing_enabled(&selinux_state) &&

			    !security_get_allow_unknown(&selinux_state))

				return rc;

			rc = 0;

		} else if (rc == -ENOENT) {

			/* -ENOENT is a missing socket/class mapping, ignore */

			rc = 0;

		} else {

			return rc;

		}

		/* Ignore */

		if (err == -ENOENT)

			err = 0;

		goto out;

		/* move to the next message after applying netlink padding */

		msg_len = NLMSG_ALIGN(nlh->nlmsg_len);

		if (msg_len >= data_len)

			return 0;

		data_len -= msg_len;

		data += msg_len;

	}

	err = sock_has_perm(sk, perm);

out:

	return err;

	return rc;

}

#ifdef CONFIG_NETFILTER