/*
 * L2TPv3 IP encapsulation support for IPv6
 *
 * Copyright (c) 2012 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 <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 <linux/in6.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/inet6_hashtables.h>
#include <net/tcp_states.h>
#include <net/protocol.h>
#include <net/xfrm.h>

#include <net/transp_v6.h>
#include <net/addrconf.h>
#include <net/ip6_route.h>

#include "l2tp_core.h"

struct l2tp_ip6_sock {
        /* inet_sock has to be the first member of l2tp_ip6_sock */
        struct inet_sock        inet;

        u32                     conn_id;
        u32                     peer_conn_id;

        /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
           inet6_sk_generic */
        struct ipv6_pinfo       inet6;
};

static DEFINE_RWLOCK(l2tp_ip6_lock);
static struct hlist_head l2tp_ip6_table;
static struct hlist_head l2tp_ip6_bind_table;

static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
{
        return (struct l2tp_ip6_sock *)sk;
}

static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
                                           const struct in6_addr *laddr,
                                           const struct in6_addr *raddr,
                                           int dif, u32 tunnel_id)
{
        struct sock *sk;

        sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
                const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
                const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
                const struct l2tp_ip6_sock *l2tp = l2tp_ip6_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 (sk_laddr && !ipv6_addr_any(sk_laddr) &&
                    !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
                        continue;

                if (!ipv6_addr_any(sk_raddr) && raddr &&
                    !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, 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_ip6_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 ipv6hdr *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, NULL, 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);
        }

        if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
                goto discard_sess;

        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 = ipv6_hdr(skb);

        read_lock_bh(&l2tp_ip6_lock);
        sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
                                    inet6_iif(skb), tunnel_id);
        if (!sk) {
                read_unlock_bh(&l2tp_ip6_lock);
                goto discard;
        }
        sock_hold(sk);
        read_unlock_bh(&l2tp_ip6_lock);

        if (!xfrm6_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_ip6_open(struct sock *sk)
{
        /* Prevent autobind. We don't have ports. */
        inet_sk(sk)->inet_num = IPPROTO_L2TP;

        write_lock_bh(&l2tp_ip6_lock);
        sk_add_node(sk, &l2tp_ip6_table);
        write_unlock_bh(&l2tp_ip6_lock);

        return 0;
}

static void l2tp_ip6_close(struct sock *sk, long timeout)
{
        write_lock_bh(&l2tp_ip6_lock);
        hlist_del_init(&sk->sk_bind_node);
        sk_del_node_init(sk);
        write_unlock_bh(&l2tp_ip6_lock);

        sk_common_release(sk);
}

static void l2tp_ip6_destroy_sock(struct sock *sk)
{
        struct l2tp_tunnel *tunnel = sk->sk_user_data;

        lock_sock(sk);
        ip6_flush_pending_frames(sk);
        release_sock(sk);

        if (tunnel)
                l2tp_tunnel_delete(tunnel);

        inet6_destroy_sock(sk);
}

static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
        struct net *net = sock_net(sk);
        __be32 v4addr = 0;
        int bound_dev_if;
        int addr_type;
        int err;

        if (addr->l2tp_family != AF_INET6)
                return -EINVAL;
        if (addr_len < sizeof(*addr))
                return -EINVAL;

        addr_type = ipv6_addr_type(&addr->l2tp_addr);

        /* l2tp_ip6 sockets are IPv6 only */
        if (addr_type == IPV6_ADDR_MAPPED)
                return -EADDRNOTAVAIL;

        /* L2TP is point-point, not multicast */
        if (addr_type & IPV6_ADDR_MULTICAST)
                return -EADDRNOTAVAIL;

        lock_sock(sk);

        err = -EINVAL;
        if (!sock_flag(sk, SOCK_ZAPPED))
                goto out_unlock;

        if (sk->sk_state != TCP_CLOSE)
                goto out_unlock;

        bound_dev_if = sk->sk_bound_dev_if;

        /* Check if the address belongs to the host. */
        rcu_read_lock();
        if (addr_type != IPV6_ADDR_ANY) {
                struct net_device *dev = NULL;

                if (addr_type & IPV6_ADDR_LINKLOCAL) {
                        if (addr->l2tp_scope_id)
                                bound_dev_if = addr->l2tp_scope_id;

                        /* Binding to link-local address requires an
                         * interface.
                         */
                        if (!bound_dev_if)
                                goto out_unlock_rcu;

                        err = -ENODEV;
                        dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
                        if (!dev)
                                goto out_unlock_rcu;
                }

                /* ipv4 addr of the socket is invalid.  Only the
                 * unspecified and mapped address have a v4 equivalent.
                 */
                v4addr = LOOPBACK4_IPV6;
                err = -EADDRNOTAVAIL;
                if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
                        goto out_unlock_rcu;
        }
        rcu_read_unlock();

        write_lock_bh(&l2tp_ip6_lock);
        if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
                                   addr->l2tp_conn_id)) {
                write_unlock_bh(&l2tp_ip6_lock);
                err = -EADDRINUSE;
                goto out_unlock;
        }

        inet->inet_saddr = v4addr;
        inet->inet_rcv_saddr = v4addr;
        sk->sk_bound_dev_if = bound_dev_if;
        sk->sk_v6_rcv_saddr = addr->l2tp_addr;
        np->saddr = addr->l2tp_addr;

        l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;

        sk_add_bind_node(sk, &l2tp_ip6_bind_table);
        sk_del_node_init(sk);
        write_unlock_bh(&l2tp_ip6_lock);

        sock_reset_flag(sk, SOCK_ZAPPED);
        release_sock(sk);
        return 0;

out_unlock_rcu:
        rcu_read_unlock();
out_unlock:
        release_sock(sk);

        return err;
}

static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
                            int addr_len)
{
        struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
        struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
        struct in6_addr *daddr;
        int     addr_type;
        int rc;

        if (addr_len < sizeof(*lsa))
                return -EINVAL;

        if (usin->sin6_family != AF_INET6)
                return -EINVAL;

        addr_type = ipv6_addr_type(&usin->sin6_addr);
        if (addr_type & IPV6_ADDR_MULTICAST)
                return -EINVAL;

        if (addr_type & IPV6_ADDR_MAPPED) {
                daddr = &usin->sin6_addr;
                if (ipv4_is_multicast(daddr->s6_addr32[3]))
                        return -EINVAL;
        }

        lock_sock(sk);

         /* Must bind first - autobinding does not work */
        if (sock_flag(sk, SOCK_ZAPPED)) {
                rc = -EINVAL;
                goto out_sk;
        }

        rc = __ip6_datagram_connect(sk, uaddr, addr_len);
        if (rc < 0)
                goto out_sk;

        l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;

        write_lock_bh(&l2tp_ip6_lock);
        hlist_del_init(&sk->sk_bind_node);
        sk_add_bind_node(sk, &l2tp_ip6_bind_table);
        write_unlock_bh(&l2tp_ip6_lock);

out_sk:
        release_sock(sk);

        return rc;
}

static int l2tp_ip6_disconnect(struct sock *sk, int flags)
{
        if (sock_flag(sk, SOCK_ZAPPED))
                return 0;

        return __udp_disconnect(sk, flags);
}

static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
                            int peer)
{
        struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
        struct sock *sk = sock->sk;
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);

        lsa->l2tp_family = AF_INET6;
        lsa->l2tp_flowinfo = 0;
        lsa->l2tp_scope_id = 0;
        lsa->l2tp_unused = 0;
        if (peer) {
                if (!lsk->peer_conn_id)
                        return -ENOTCONN;
                lsa->l2tp_conn_id = lsk->peer_conn_id;
                lsa->l2tp_addr = sk->sk_v6_daddr;
                if (np->sndflow)
                        lsa->l2tp_flowinfo = np->flow_label;
        } else {
                if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
                        lsa->l2tp_addr = np->saddr;
                else
                        lsa->l2tp_addr = sk->sk_v6_rcv_saddr;

                lsa->l2tp_conn_id = lsk->conn_id;
        }
        if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
                lsa->l2tp_scope_id = sk->sk_bound_dev_if;
        return sizeof(*lsa);
}

static int l2tp_ip6_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 -1;
}

static int l2tp_ip6_push_pending_frames(struct sock *sk)
{
        struct sk_buff *skb;
        __be32 *transhdr = NULL;
        int err = 0;

        skb = skb_peek(&sk->sk_write_queue);
        if (skb == NULL)
                goto out;

        transhdr = (__be32 *)skb_transport_header(skb);
        *transhdr = 0;

        err = ip6_push_pending_frames(sk);

out:
        return err;
}

/* Userspace will call sendmsg() on the tunnel socket to send L2TP
 * control frames.
 */
static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
        struct ipv6_txoptions opt_space;
        DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
        struct in6_addr *daddr, *final_p, final;
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct ipv6_txoptions *opt_to_free = NULL;
        struct ipv6_txoptions *opt = NULL;
        struct ip6_flowlabel *flowlabel = NULL;
        struct dst_entry *dst = NULL;
        struct flowi6 fl6;
        struct sockcm_cookie sockc_unused = {0};
        struct ipcm6_cookie ipc6;
        int addr_len = msg->msg_namelen;
        int transhdrlen = 4; /* zero session-id */
        int ulen = len + transhdrlen;
        int err;

        /* Rough check on arithmetic overflow,
           better check is made in ip6_append_data().
         */
        if (len > INT_MAX)
                return -EMSGSIZE;

        /* Mirror BSD error message compatibility */
        if (msg->msg_flags & MSG_OOB)
                return -EOPNOTSUPP;

        /*
         *      Get and verify the address.
         */
        memset(&fl6, 0, sizeof(fl6));

        fl6.flowi6_mark = sk->sk_mark;
        fl6.flowi6_uid = sk->sk_uid;

        ipc6.hlimit = -1;
        ipc6.tclass = -1;
        ipc6.dontfrag = -1;

        if (lsa) {
                if (addr_len < SIN6_LEN_RFC2133)
                        return -EINVAL;

                if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
                        return -EAFNOSUPPORT;

                daddr = &lsa->l2tp_addr;
                if (np->sndflow) {
                        fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
                        if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
                                flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
                                if (flowlabel == NULL)
                                        return -EINVAL;
                        }
                }

                /*
                 * Otherwise it will be difficult to maintain
                 * sk->sk_dst_cache.
                 */
                if (sk->sk_state == TCP_ESTABLISHED &&
                    ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
                        daddr = &sk->sk_v6_daddr;

                if (addr_len >= sizeof(struct sockaddr_in6) &&
                    lsa->l2tp_scope_id &&
                    ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
                        fl6.flowi6_oif = lsa->l2tp_scope_id;
        } else {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;

                daddr = &sk->sk_v6_daddr;
                fl6.flowlabel = np->flow_label;
        }

        if (fl6.flowi6_oif == 0)
                fl6.flowi6_oif = sk->sk_bound_dev_if;

        if (msg->msg_controllen) {
                opt = &opt_space;
                memset(opt, 0, sizeof(struct ipv6_txoptions));
                opt->tot_len = sizeof(struct ipv6_txoptions);
                ipc6.opt = opt;

                err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
                                            &sockc_unused);
                if (err < 0) {
                        fl6_sock_release(flowlabel);
                        return err;
                }
                if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
                        flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
                        if (flowlabel == NULL)
                                return -EINVAL;
                }
                if (!(opt->opt_nflen|opt->opt_flen))
                        opt = NULL;
        }

        if (!opt) {
                opt = txopt_get(np);
                opt_to_free = opt;
        }
        if (flowlabel)
                opt = fl6_merge_options(&opt_space, flowlabel, opt);
        opt = ipv6_fixup_options(&opt_space, opt);
        ipc6.opt = opt;

        fl6.flowi6_proto = sk->sk_protocol;
        if (!ipv6_addr_any(daddr))
                fl6.daddr = *daddr;
        else
                fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
        if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
                fl6.saddr = np->saddr;

        final_p = fl6_update_dst(&fl6, opt, &final);

        if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
                fl6.flowi6_oif = np->mcast_oif;
        else if (!fl6.flowi6_oif)
                fl6.flowi6_oif = np->ucast_oif;

        security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));

        if (ipc6.tclass < 0)
                ipc6.tclass = np->tclass;

        fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);

        dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
        if (IS_ERR(dst)) {
                err = PTR_ERR(dst);
                goto out;
        }

        if (ipc6.hlimit < 0)
                ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);

        if (ipc6.dontfrag < 0)
                ipc6.dontfrag = np->dontfrag;

        if (msg->msg_flags & MSG_CONFIRM)
                goto do_confirm;

back_from_confirm:
        lock_sock(sk);
        err = ip6_append_data(sk, ip_generic_getfrag, msg,
                              ulen, transhdrlen, &ipc6,
                              &fl6, (struct rt6_info *)dst,
                              msg->msg_flags, &sockc_unused);
        if (err)
                ip6_flush_pending_frames(sk);
        else if (!(msg->msg_flags & MSG_MORE))
                err = l2tp_ip6_push_pending_frames(sk);
        release_sock(sk);
done:
        dst_release(dst);
out:
        fl6_sock_release(flowlabel);
        txopt_put(opt_to_free);

        return err < 0 ? err : len;

do_confirm:
        if (msg->msg_flags & MSG_PROBE)
                dst_confirm_neigh(dst, &fl6.daddr);
        if (!(msg->msg_flags & MSG_PROBE) || len)
                goto back_from_confirm;
        err = 0;
        goto done;
}

static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
                            int noblock, int flags, int *addr_len)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
        size_t copied = 0;
        int err = -EOPNOTSUPP;
        struct sk_buff *skb;

        if (flags & MSG_OOB)
                goto out;

        if (flags & MSG_ERRQUEUE)
                return ipv6_recv_error(sk, msg, len, addr_len);

        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 (lsa) {
                lsa->l2tp_family = AF_INET6;
                lsa->l2tp_unused = 0;
                lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
                lsa->l2tp_flowinfo = 0;
                lsa->l2tp_scope_id = 0;
                lsa->l2tp_conn_id = 0;
                if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
                        lsa->l2tp_scope_id = inet6_iif(skb);
                *addr_len = sizeof(*lsa);
        }

        if (np->rxopt.all)
                ip6_datagram_recv_ctl(sk, msg, skb);

        if (flags & MSG_TRUNC)
                copied = skb->len;
done:
        skb_free_datagram(sk, skb);
out:
        return err ? err : copied;
}

static struct proto l2tp_ip6_prot = {
        .name              = "L2TP/IPv6",
        .owner             = THIS_MODULE,
        .init              = l2tp_ip6_open,
        .close             = l2tp_ip6_close,
        .bind              = l2tp_ip6_bind,
        .connect           = l2tp_ip6_connect,
        .disconnect        = l2tp_ip6_disconnect,
        .ioctl             = l2tp_ioctl,
        .destroy           = l2tp_ip6_destroy_sock,
        .setsockopt        = ipv6_setsockopt,
        .getsockopt        = ipv6_getsockopt,
        .sendmsg           = l2tp_ip6_sendmsg,
        .recvmsg           = l2tp_ip6_recvmsg,
        .backlog_rcv       = l2tp_ip6_backlog_recv,
        .hash              = inet6_hash,
        .unhash            = inet_unhash,
        .obj_size          = sizeof(struct l2tp_ip6_sock),
#ifdef CONFIG_COMPAT
        .compat_setsockopt = compat_ipv6_setsockopt,
        .compat_getsockopt = compat_ipv6_getsockopt,
#endif
};

static const struct proto_ops l2tp_ip6_ops = {
        .family            = PF_INET6,
        .owner             = THIS_MODULE,
        .release           = inet6_release,
        .bind              = inet6_bind,
        .connect           = inet_dgram_connect,
        .socketpair        = sock_no_socketpair,
        .accept            = sock_no_accept,
        .getname           = l2tp_ip6_getname,
        .poll              = datagram_poll,
        .ioctl             = inet6_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_ip6_protosw = {
        .type           = SOCK_DGRAM,
        .protocol       = IPPROTO_L2TP,
        .prot           = &l2tp_ip6_prot,
        .ops            = &l2tp_ip6_ops,
};

static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
        .handler        = l2tp_ip6_recv,
};

static int __init l2tp_ip6_init(void)
{
        int err;

        pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");

        err = proto_register(&l2tp_ip6_prot, 1);
        if (err != 0)
                goto out;

        err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
        if (err)
                goto out1;

        inet6_register_protosw(&l2tp_ip6_protosw);
        return 0;

out1:
        proto_unregister(&l2tp_ip6_prot);
out:
        return err;
}

static void __exit l2tp_ip6_exit(void)
{
        inet6_unregister_protosw(&l2tp_ip6_protosw);
        inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
        proto_unregister(&l2tp_ip6_prot);
}

module_init(l2tp_ip6_init);
module_exit(l2tp_ip6_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
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_INET6, 2, IPPROTO_L2TP);
MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);