v4.19.13 snapshot.
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
new file mode 100644
index 0000000..35f6f86
--- /dev/null
+++ b/net/l2tp/l2tp_ip.c
@@ -0,0 +1,686 @@
+/*
+ * L2TPv3 IP encapsulation support
+ *
+ * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <asm/ioctls.h>
+#include <linux/icmp.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/random.h>
+#include <linux/socket.h>
+#include <linux/l2tp.h>
+#include <linux/in.h>
+#include <net/sock.h>
+#include <net/ip.h>
+#include <net/icmp.h>
+#include <net/udp.h>
+#include <net/inet_common.h>
+#include <net/inet_hashtables.h>
+#include <net/tcp_states.h>
+#include <net/protocol.h>
+#include <net/xfrm.h>
+
+#include "l2tp_core.h"
+
+struct l2tp_ip_sock {
+ /* inet_sock has to be the first member of l2tp_ip_sock */
+ struct inet_sock inet;
+
+ u32 conn_id;
+ u32 peer_conn_id;
+};
+
+static DEFINE_RWLOCK(l2tp_ip_lock);
+static struct hlist_head l2tp_ip_table;
+static struct hlist_head l2tp_ip_bind_table;
+
+static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
+{
+ return (struct l2tp_ip_sock *)sk;
+}
+
+static struct sock *__l2tp_ip_bind_lookup(const struct net *net, __be32 laddr,
+ __be32 raddr, int dif, u32 tunnel_id)
+{
+ struct sock *sk;
+
+ sk_for_each_bound(sk, &l2tp_ip_bind_table) {
+ const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
+ const struct inet_sock *inet = inet_sk(sk);
+
+ if (!net_eq(sock_net(sk), net))
+ continue;
+
+ if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
+ continue;
+
+ if (inet->inet_rcv_saddr && laddr &&
+ inet->inet_rcv_saddr != laddr)
+ continue;
+
+ if (inet->inet_daddr && raddr && inet->inet_daddr != raddr)
+ continue;
+
+ if (l2tp->conn_id != tunnel_id)
+ continue;
+
+ goto found;
+ }
+
+ sk = NULL;
+found:
+ return sk;
+}
+
+/* When processing receive frames, there are two cases to
+ * consider. Data frames consist of a non-zero session-id and an
+ * optional cookie. Control frames consist of a regular L2TP header
+ * preceded by 32-bits of zeros.
+ *
+ * L2TPv3 Session Header Over IP
+ *
+ * 0 1 2 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Session ID |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Cookie (optional, maximum 64 bits)...
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * L2TPv3 Control Message Header Over IP
+ *
+ * 0 1 2 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | (32 bits of zeros) |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Control Connection ID |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Ns | Nr |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * All control frames are passed to userspace.
+ */
+static int l2tp_ip_recv(struct sk_buff *skb)
+{
+ struct net *net = dev_net(skb->dev);
+ struct sock *sk;
+ u32 session_id;
+ u32 tunnel_id;
+ unsigned char *ptr, *optr;
+ struct l2tp_session *session;
+ struct l2tp_tunnel *tunnel = NULL;
+ struct iphdr *iph;
+ int length;
+
+ if (!pskb_may_pull(skb, 4))
+ goto discard;
+
+ /* Point to L2TP header */
+ optr = ptr = skb->data;
+ session_id = ntohl(*((__be32 *) ptr));
+ ptr += 4;
+
+ /* RFC3931: L2TP/IP packets have the first 4 bytes containing
+ * the session_id. If it is 0, the packet is a L2TP control
+ * frame and the session_id value can be discarded.
+ */
+ if (session_id == 0) {
+ __skb_pull(skb, 4);
+ goto pass_up;
+ }
+
+ /* Ok, this is a data packet. Lookup the session. */
+ session = l2tp_session_get(net, session_id);
+ if (!session)
+ goto discard;
+
+ tunnel = session->tunnel;
+ if (!tunnel)
+ goto discard_sess;
+
+ /* Trace packet contents, if enabled */
+ if (tunnel->debug & L2TP_MSG_DATA) {
+ length = min(32u, skb->len);
+ if (!pskb_may_pull(skb, length))
+ goto discard_sess;
+
+ /* Point to L2TP header */
+ optr = ptr = skb->data;
+ ptr += 4;
+ pr_debug("%s: ip recv\n", tunnel->name);
+ print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
+ }
+
+ l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
+ l2tp_session_dec_refcount(session);
+
+ return 0;
+
+pass_up:
+ /* Get the tunnel_id from the L2TP header */
+ if (!pskb_may_pull(skb, 12))
+ goto discard;
+
+ if ((skb->data[0] & 0xc0) != 0xc0)
+ goto discard;
+
+ tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
+ iph = (struct iphdr *)skb_network_header(skb);
+
+ read_lock_bh(&l2tp_ip_lock);
+ sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb),
+ tunnel_id);
+ if (!sk) {
+ read_unlock_bh(&l2tp_ip_lock);
+ goto discard;
+ }
+ sock_hold(sk);
+ read_unlock_bh(&l2tp_ip_lock);
+
+ if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
+ goto discard_put;
+
+ nf_reset(skb);
+
+ return sk_receive_skb(sk, skb, 1);
+
+discard_sess:
+ l2tp_session_dec_refcount(session);
+ goto discard;
+
+discard_put:
+ sock_put(sk);
+
+discard:
+ kfree_skb(skb);
+ return 0;
+}
+
+static int l2tp_ip_open(struct sock *sk)
+{
+ /* Prevent autobind. We don't have ports. */
+ inet_sk(sk)->inet_num = IPPROTO_L2TP;
+
+ write_lock_bh(&l2tp_ip_lock);
+ sk_add_node(sk, &l2tp_ip_table);
+ write_unlock_bh(&l2tp_ip_lock);
+
+ return 0;
+}
+
+static void l2tp_ip_close(struct sock *sk, long timeout)
+{
+ write_lock_bh(&l2tp_ip_lock);
+ hlist_del_init(&sk->sk_bind_node);
+ sk_del_node_init(sk);
+ write_unlock_bh(&l2tp_ip_lock);
+ sk_common_release(sk);
+}
+
+static void l2tp_ip_destroy_sock(struct sock *sk)
+{
+ struct sk_buff *skb;
+ struct l2tp_tunnel *tunnel = sk->sk_user_data;
+
+ while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
+ kfree_skb(skb);
+
+ if (tunnel)
+ l2tp_tunnel_delete(tunnel);
+}
+
+static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+{
+ struct inet_sock *inet = inet_sk(sk);
+ struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
+ struct net *net = sock_net(sk);
+ int ret;
+ int chk_addr_ret;
+
+ if (addr_len < sizeof(struct sockaddr_l2tpip))
+ return -EINVAL;
+ if (addr->l2tp_family != AF_INET)
+ return -EINVAL;
+
+ lock_sock(sk);
+
+ ret = -EINVAL;
+ if (!sock_flag(sk, SOCK_ZAPPED))
+ goto out;
+
+ if (sk->sk_state != TCP_CLOSE)
+ goto out;
+
+ chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
+ ret = -EADDRNOTAVAIL;
+ if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
+ chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
+ goto out;
+
+ if (addr->l2tp_addr.s_addr)
+ inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
+ if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
+ inet->inet_saddr = 0; /* Use device */
+
+ write_lock_bh(&l2tp_ip_lock);
+ if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr, 0,
+ sk->sk_bound_dev_if, addr->l2tp_conn_id)) {
+ write_unlock_bh(&l2tp_ip_lock);
+ ret = -EADDRINUSE;
+ goto out;
+ }
+
+ sk_dst_reset(sk);
+ l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
+
+ sk_add_bind_node(sk, &l2tp_ip_bind_table);
+ sk_del_node_init(sk);
+ write_unlock_bh(&l2tp_ip_lock);
+
+ ret = 0;
+ sock_reset_flag(sk, SOCK_ZAPPED);
+
+out:
+ release_sock(sk);
+
+ return ret;
+}
+
+static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+{
+ struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
+ int rc;
+
+ if (addr_len < sizeof(*lsa))
+ return -EINVAL;
+
+ if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
+ return -EINVAL;
+
+ lock_sock(sk);
+
+ /* Must bind first - autobinding does not work */
+ if (sock_flag(sk, SOCK_ZAPPED)) {
+ rc = -EINVAL;
+ goto out_sk;
+ }
+
+ rc = __ip4_datagram_connect(sk, uaddr, addr_len);
+ if (rc < 0)
+ goto out_sk;
+
+ l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
+
+ write_lock_bh(&l2tp_ip_lock);
+ hlist_del_init(&sk->sk_bind_node);
+ sk_add_bind_node(sk, &l2tp_ip_bind_table);
+ write_unlock_bh(&l2tp_ip_lock);
+
+out_sk:
+ release_sock(sk);
+
+ return rc;
+}
+
+static int l2tp_ip_disconnect(struct sock *sk, int flags)
+{
+ if (sock_flag(sk, SOCK_ZAPPED))
+ return 0;
+
+ return __udp_disconnect(sk, flags);
+}
+
+static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
+ int peer)
+{
+ struct sock *sk = sock->sk;
+ struct inet_sock *inet = inet_sk(sk);
+ struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
+ struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
+
+ memset(lsa, 0, sizeof(*lsa));
+ lsa->l2tp_family = AF_INET;
+ if (peer) {
+ if (!inet->inet_dport)
+ return -ENOTCONN;
+ lsa->l2tp_conn_id = lsk->peer_conn_id;
+ lsa->l2tp_addr.s_addr = inet->inet_daddr;
+ } else {
+ __be32 addr = inet->inet_rcv_saddr;
+ if (!addr)
+ addr = inet->inet_saddr;
+ lsa->l2tp_conn_id = lsk->conn_id;
+ lsa->l2tp_addr.s_addr = addr;
+ }
+ return sizeof(*lsa);
+}
+
+static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
+{
+ int rc;
+
+ /* Charge it to the socket, dropping if the queue is full. */
+ rc = sock_queue_rcv_skb(sk, skb);
+ if (rc < 0)
+ goto drop;
+
+ return 0;
+
+drop:
+ IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
+ kfree_skb(skb);
+ return 0;
+}
+
+/* Userspace will call sendmsg() on the tunnel socket to send L2TP
+ * control frames.
+ */
+static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
+{
+ struct sk_buff *skb;
+ int rc;
+ struct inet_sock *inet = inet_sk(sk);
+ struct rtable *rt = NULL;
+ struct flowi4 *fl4;
+ int connected = 0;
+ __be32 daddr;
+
+ lock_sock(sk);
+
+ rc = -ENOTCONN;
+ if (sock_flag(sk, SOCK_DEAD))
+ goto out;
+
+ /* Get and verify the address. */
+ if (msg->msg_name) {
+ DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
+ rc = -EINVAL;
+ if (msg->msg_namelen < sizeof(*lip))
+ goto out;
+
+ if (lip->l2tp_family != AF_INET) {
+ rc = -EAFNOSUPPORT;
+ if (lip->l2tp_family != AF_UNSPEC)
+ goto out;
+ }
+
+ daddr = lip->l2tp_addr.s_addr;
+ } else {
+ rc = -EDESTADDRREQ;
+ if (sk->sk_state != TCP_ESTABLISHED)
+ goto out;
+
+ daddr = inet->inet_daddr;
+ connected = 1;
+ }
+
+ /* Allocate a socket buffer */
+ rc = -ENOMEM;
+ skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
+ 4 + len, 0, GFP_KERNEL);
+ if (!skb)
+ goto error;
+
+ /* Reserve space for headers, putting IP header on 4-byte boundary. */
+ skb_reserve(skb, 2 + NET_SKB_PAD);
+ skb_reset_network_header(skb);
+ skb_reserve(skb, sizeof(struct iphdr));
+ skb_reset_transport_header(skb);
+
+ /* Insert 0 session_id */
+ *((__be32 *) skb_put(skb, 4)) = 0;
+
+ /* Copy user data into skb */
+ rc = memcpy_from_msg(skb_put(skb, len), msg, len);
+ if (rc < 0) {
+ kfree_skb(skb);
+ goto error;
+ }
+
+ fl4 = &inet->cork.fl.u.ip4;
+ if (connected)
+ rt = (struct rtable *) __sk_dst_check(sk, 0);
+
+ rcu_read_lock();
+ if (rt == NULL) {
+ const struct ip_options_rcu *inet_opt;
+
+ inet_opt = rcu_dereference(inet->inet_opt);
+
+ /* Use correct destination address if we have options. */
+ if (inet_opt && inet_opt->opt.srr)
+ daddr = inet_opt->opt.faddr;
+
+ /* If this fails, retransmit mechanism of transport layer will
+ * keep trying until route appears or the connection times
+ * itself out.
+ */
+ rt = ip_route_output_ports(sock_net(sk), fl4, sk,
+ daddr, inet->inet_saddr,
+ inet->inet_dport, inet->inet_sport,
+ sk->sk_protocol, RT_CONN_FLAGS(sk),
+ sk->sk_bound_dev_if);
+ if (IS_ERR(rt))
+ goto no_route;
+ if (connected) {
+ sk_setup_caps(sk, &rt->dst);
+ } else {
+ skb_dst_set(skb, &rt->dst);
+ goto xmit;
+ }
+ }
+
+ /* We dont need to clone dst here, it is guaranteed to not disappear.
+ * __dev_xmit_skb() might force a refcount if needed.
+ */
+ skb_dst_set_noref(skb, &rt->dst);
+
+xmit:
+ /* Queue the packet to IP for output */
+ rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
+ rcu_read_unlock();
+
+error:
+ if (rc >= 0)
+ rc = len;
+
+out:
+ release_sock(sk);
+ return rc;
+
+no_route:
+ rcu_read_unlock();
+ IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
+ kfree_skb(skb);
+ rc = -EHOSTUNREACH;
+ goto out;
+}
+
+static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t len, int noblock, int flags, int *addr_len)
+{
+ struct inet_sock *inet = inet_sk(sk);
+ size_t copied = 0;
+ int err = -EOPNOTSUPP;
+ DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
+ struct sk_buff *skb;
+
+ if (flags & MSG_OOB)
+ goto out;
+
+ skb = skb_recv_datagram(sk, flags, noblock, &err);
+ if (!skb)
+ goto out;
+
+ copied = skb->len;
+ if (len < copied) {
+ msg->msg_flags |= MSG_TRUNC;
+ copied = len;
+ }
+
+ err = skb_copy_datagram_msg(skb, 0, msg, copied);
+ if (err)
+ goto done;
+
+ sock_recv_timestamp(msg, sk, skb);
+
+ /* Copy the address. */
+ if (sin) {
+ sin->sin_family = AF_INET;
+ sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
+ sin->sin_port = 0;
+ memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
+ *addr_len = sizeof(*sin);
+ }
+ if (inet->cmsg_flags)
+ ip_cmsg_recv(msg, skb);
+ if (flags & MSG_TRUNC)
+ copied = skb->len;
+done:
+ skb_free_datagram(sk, skb);
+out:
+ return err ? err : copied;
+}
+
+int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg)
+{
+ struct sk_buff *skb;
+ int amount;
+
+ switch (cmd) {
+ case SIOCOUTQ:
+ amount = sk_wmem_alloc_get(sk);
+ break;
+ case SIOCINQ:
+ spin_lock_bh(&sk->sk_receive_queue.lock);
+ skb = skb_peek(&sk->sk_receive_queue);
+ amount = skb ? skb->len : 0;
+ spin_unlock_bh(&sk->sk_receive_queue.lock);
+ break;
+
+ default:
+ return -ENOIOCTLCMD;
+ }
+
+ return put_user(amount, (int __user *)arg);
+}
+EXPORT_SYMBOL(l2tp_ioctl);
+
+static struct proto l2tp_ip_prot = {
+ .name = "L2TP/IP",
+ .owner = THIS_MODULE,
+ .init = l2tp_ip_open,
+ .close = l2tp_ip_close,
+ .bind = l2tp_ip_bind,
+ .connect = l2tp_ip_connect,
+ .disconnect = l2tp_ip_disconnect,
+ .ioctl = l2tp_ioctl,
+ .destroy = l2tp_ip_destroy_sock,
+ .setsockopt = ip_setsockopt,
+ .getsockopt = ip_getsockopt,
+ .sendmsg = l2tp_ip_sendmsg,
+ .recvmsg = l2tp_ip_recvmsg,
+ .backlog_rcv = l2tp_ip_backlog_recv,
+ .hash = inet_hash,
+ .unhash = inet_unhash,
+ .obj_size = sizeof(struct l2tp_ip_sock),
+#ifdef CONFIG_COMPAT
+ .compat_setsockopt = compat_ip_setsockopt,
+ .compat_getsockopt = compat_ip_getsockopt,
+#endif
+};
+
+static const struct proto_ops l2tp_ip_ops = {
+ .family = PF_INET,
+ .owner = THIS_MODULE,
+ .release = inet_release,
+ .bind = inet_bind,
+ .connect = inet_dgram_connect,
+ .socketpair = sock_no_socketpair,
+ .accept = sock_no_accept,
+ .getname = l2tp_ip_getname,
+ .poll = datagram_poll,
+ .ioctl = inet_ioctl,
+ .listen = sock_no_listen,
+ .shutdown = inet_shutdown,
+ .setsockopt = sock_common_setsockopt,
+ .getsockopt = sock_common_getsockopt,
+ .sendmsg = inet_sendmsg,
+ .recvmsg = sock_common_recvmsg,
+ .mmap = sock_no_mmap,
+ .sendpage = sock_no_sendpage,
+#ifdef CONFIG_COMPAT
+ .compat_setsockopt = compat_sock_common_setsockopt,
+ .compat_getsockopt = compat_sock_common_getsockopt,
+#endif
+};
+
+static struct inet_protosw l2tp_ip_protosw = {
+ .type = SOCK_DGRAM,
+ .protocol = IPPROTO_L2TP,
+ .prot = &l2tp_ip_prot,
+ .ops = &l2tp_ip_ops,
+};
+
+static struct net_protocol l2tp_ip_protocol __read_mostly = {
+ .handler = l2tp_ip_recv,
+ .netns_ok = 1,
+};
+
+static int __init l2tp_ip_init(void)
+{
+ int err;
+
+ pr_info("L2TP IP encapsulation support (L2TPv3)\n");
+
+ err = proto_register(&l2tp_ip_prot, 1);
+ if (err != 0)
+ goto out;
+
+ err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
+ if (err)
+ goto out1;
+
+ inet_register_protosw(&l2tp_ip_protosw);
+ return 0;
+
+out1:
+ proto_unregister(&l2tp_ip_prot);
+out:
+ return err;
+}
+
+static void __exit l2tp_ip_exit(void)
+{
+ inet_unregister_protosw(&l2tp_ip_protosw);
+ inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
+ proto_unregister(&l2tp_ip_prot);
+}
+
+module_init(l2tp_ip_init);
+module_exit(l2tp_ip_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("L2TP over IP");
+MODULE_VERSION("1.0");
+
+/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
+ * enums
+ */
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
+MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_L2TP);