/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2009-2010 Ana Kukec <anchie@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/priv.h>
#include <sys/protosw.h>
#include <sys/sdt.h>
#include <sys/systm.h>
#include <sys/socket.h>
#include <sys/sockbuf.h>
#include <sys/socketvar.h>
#include <sys/types.h>

#include <net/route.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_kdtrace.h>
#include <netinet/ip_var.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>

#include <netinet6/in6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/scope6_var.h>
#include <netinet6/send.h>

static MALLOC_DEFINE(M_SEND, "send", "Secure Neighbour Discovery");

/*
 * The socket used to communicate with the SeND daemon.
 */
VNET_DEFINE_STATIC(struct socket *, send_so);
#define V_send_so       VNET(send_so)

u_long  send_sendspace  = 8 * (1024 + sizeof(struct sockaddr_send));
u_long  send_recvspace  = 9216;

struct mtx      send_mtx;
#define SEND_LOCK_INIT()        mtx_init(&send_mtx, "send_mtx", NULL, MTX_DEF)
#define SEND_LOCK()             mtx_lock(&send_mtx)
#define SEND_UNLOCK()           mtx_unlock(&send_mtx)
#define SEND_LOCK_DESTROY()     mtx_destroy(&send_mtx)

static int
send_attach(struct socket *so, int proto, struct thread *td)
{
        int error;

        SEND_LOCK();
        if (V_send_so != NULL) {
                SEND_UNLOCK();
                return (EEXIST);
        }

        error = priv_check(td, PRIV_NETINET_RAW);
        if (error) {
                SEND_UNLOCK();
                return(error);
        }

        if (proto != IPPROTO_SEND) {
                SEND_UNLOCK();
                return (EPROTONOSUPPORT);
        }
        error = soreserve(so, send_sendspace, send_recvspace);
        if (error) {
                SEND_UNLOCK();
                return(error);
        }

        V_send_so = so;
        SEND_UNLOCK();

        return (0);
}

static int
send_output(struct mbuf *m, struct ifnet *ifp, int direction)
{
        struct ip6_hdr *ip6;
        struct sockaddr_in6 dst;
        struct icmp6_hdr *icmp6;
        struct epoch_tracker et;
        int icmp6len;
        int error;

        /*
         * Receive incoming (SeND-protected) or outgoing traffic
         * (SeND-validated) from the SeND user space application.
         */

        switch (direction) {
        case SND_IN:
                if (m->m_len < (sizeof(struct ip6_hdr) +
                    sizeof(struct icmp6_hdr))) {
                        m = m_pullup(m, sizeof(struct ip6_hdr) +
                            sizeof(struct icmp6_hdr));
                        if (!m)
                                return (ENOBUFS);
                }

                /* Before passing off the mbuf record the proper interface. */
                m->m_pkthdr.rcvif = ifp;

                if (m->m_flags & M_PKTHDR)
                        icmp6len = m->m_pkthdr.len - sizeof(struct ip6_hdr);
                else
                        panic("Doh! not the first mbuf.");

                ip6 = mtod(m, struct ip6_hdr *);
                icmp6 = (struct icmp6_hdr *)(ip6 + 1);
                error = 0;

                /*
                 * Output the packet as icmp6.c:icpm6_input() would do.
                 * The mbuf is always consumed, so we do not have to
                 * care about that.
                 */
                NET_EPOCH_ENTER(et);
                switch (icmp6->icmp6_type) {
                case ND_NEIGHBOR_SOLICIT:
                        nd6_ns_input(m, sizeof(struct ip6_hdr), icmp6len);
                        break;
                case ND_NEIGHBOR_ADVERT:
                        nd6_na_input(m, sizeof(struct ip6_hdr), icmp6len);
                        break;
                case ND_REDIRECT:
                        icmp6_redirect_input(m, sizeof(struct ip6_hdr));
                        break;
                case ND_ROUTER_SOLICIT:
                        nd6_rs_input(m, sizeof(struct ip6_hdr), icmp6len);
                        break;
                case ND_ROUTER_ADVERT:
                        nd6_ra_input(m, sizeof(struct ip6_hdr), icmp6len);
                        break;
                default:
                        m_freem(m);
                        error = ENOSYS;
                }
                NET_EPOCH_EXIT(et);

                return (error);

        case SND_OUT:
                if (m->m_len < sizeof(struct ip6_hdr)) {
                        m = m_pullup(m, sizeof(struct ip6_hdr));
                        if (!m)
                                return (ENOBUFS);
                }
                ip6 = mtod(m, struct ip6_hdr *);
                if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst))
                        m->m_flags |= M_MCAST;

                bzero(&dst, sizeof(dst));
                dst.sin6_family = AF_INET6;
                dst.sin6_len = sizeof(dst);
                dst.sin6_addr = ip6->ip6_dst;

                m_clrprotoflags(m);     /* Avoid confusing lower layers. */

                IP_PROBE(send, NULL, NULL, ip6, ifp, NULL, ip6);

                /*
                 * Output the packet as nd6.c:nd6_output_lle() would do.
                 * The mbuf is always consumed, so we do not have to care
                 * about that.
                 * XXX-BZ as we added data, what about fragmenting,
                 * if now needed?
                 */
                error = ((*ifp->if_output)(ifp, m, (struct sockaddr *)&dst,
                    NULL));
                if (error)
                        error = ENOENT;
                return (error);

        default:
                panic("%s: direction %d neither SND_IN nor SND_OUT.",
                     __func__, direction);
        }
}

/*
 * Receive a SeND message from user space to be either send out by the kernel
 * or, with SeND ICMPv6 options removed, to be further processed by the icmp6
 * input path.
 */
static int
send_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
    struct mbuf *control, struct thread *td)
{
        struct sockaddr_send *sendsrc;
        struct ifnet *ifp;
        int error;

        KASSERT(V_send_so == so, ("%s: socket %p not send socket %p",
                __func__, so, V_send_so));

        sendsrc = (struct sockaddr_send *)nam;
        if (sendsrc->send_family != AF_INET6) {
                error = EAFNOSUPPORT;
                goto err;
        }
        if (sendsrc->send_len != sizeof(*sendsrc)) {
                error = EINVAL;
                goto err;
        }
        ifp = ifnet_byindex_ref(sendsrc->send_ifidx);
        if (ifp == NULL) {
                error = ENETUNREACH;
                goto err;
        }

        error = send_output(m, ifp, sendsrc->send_direction);
        if_rele(ifp);
        m = NULL;

err:
        if (control != NULL)
                m_freem(control);
        if (m != NULL)
                m_freem(m);

        return (error);
}

static void
send_close(struct socket *so)
{

        SEND_LOCK();
        if (V_send_so)
                V_send_so = NULL;
        SEND_UNLOCK();
}

/*
 * Send a SeND message to user space, that was either received and has to be
 * validated or was about to be send out and has to be handled by the SEND
 * daemon adding SeND ICMPv6 options.
 */
static int
send_input(struct mbuf *m, struct ifnet *ifp, int direction, int msglen __unused)
{
        struct ip6_hdr *ip6;
        struct sockaddr_send sendsrc;

        SEND_LOCK();
        if (V_send_so == NULL) {
                SEND_UNLOCK();
                return (-1);
        }

        /*
         * Make sure to clear any possible internally embedded scope before
         * passing the packet to user space for SeND cryptographic signature
         * validation to succeed.
         */
        ip6 = mtod(m, struct ip6_hdr *);
        in6_clearscope(&ip6->ip6_src);
        in6_clearscope(&ip6->ip6_dst);

        bzero(&sendsrc, sizeof(sendsrc));
        sendsrc.send_len = sizeof(sendsrc);
        sendsrc.send_family = AF_INET6;
        sendsrc.send_direction = direction;
        sendsrc.send_ifidx = ifp->if_index;

        /*
         * Send incoming or outgoing traffic to user space either to be
         * protected (outgoing) or validated (incoming) according to rfc3971.
         */
        SOCKBUF_LOCK(&V_send_so->so_rcv);
        if (sbappendaddr_locked(&V_send_so->so_rcv,
            (struct sockaddr *)&sendsrc, m, NULL) == 0) {
                soroverflow_locked(V_send_so);
                /* XXX stats. */
                m_freem(m);
        } else {
                sorwakeup_locked(V_send_so);
        }

        SEND_UNLOCK();
        return (0);
}

static struct protosw send_protosw = {
        .pr_type =              SOCK_RAW,
        .pr_flags =             PR_ATOMIC|PR_ADDR,
        .pr_protocol =          IPPROTO_SEND,
        .pr_attach =            send_attach,
        .pr_send =              send_send,
        .pr_detach =            send_close
};

static int
send_modevent(module_t mod, int type, void *unused)
{
#ifdef __notyet__
        VNET_ITERATOR_DECL(vnet_iter);
#endif
        int error;

        switch (type) {
        case MOD_LOAD:
                SEND_LOCK_INIT();

                error = protosw_register(&inet6domain, &send_protosw);
                if (error != 0) {
                        printf("%s:%d: MOD_LOAD pf_proto_register(): %d\n",
                           __func__, __LINE__, error);
                        SEND_LOCK_DESTROY();
                        break;
                }
                send_sendso_input_hook = send_input;
                break;
        case MOD_UNLOAD:
                /* Do not allow unloading w/o locking. */
                return (EBUSY);
#ifdef __notyet__
                VNET_LIST_RLOCK_NOSLEEP();
                SEND_LOCK();
                VNET_FOREACH(vnet_iter) {
                        CURVNET_SET(vnet_iter);
                        if (V_send_so != NULL) {
                                CURVNET_RESTORE();
                                SEND_UNLOCK();
                                VNET_LIST_RUNLOCK_NOSLEEP();
                                return (EBUSY);
                        }
                        CURVNET_RESTORE();
                }
                SEND_UNLOCK();
                VNET_LIST_RUNLOCK_NOSLEEP();
                error = protosw_unregister(&send_protosw);
                if (error == 0)
                        SEND_LOCK_DESTROY();
                send_sendso_input_hook = NULL;
                break;
#endif
        default:
                error = 0;
                break;
        }

        return (error);
}

static moduledata_t sendmod = {
        "send",
        send_modevent,
        0
};

DECLARE_MODULE(send, sendmod, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY);