/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * Copyright (c) 2010-2011 Juniper Networks, Inc.
 * Copyright (c) 2014 Kevin Lo
 * All rights reserved.
 *
 * Portions of this software were developed by Robert N. M. Watson under
 * contract to Juniper Networks, Inc.
 *
 * 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.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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.
 *
 *      $KAME: udp6_usrreq.c,v 1.27 2001/05/21 05:45:10 jinmei Exp $
 *      $KAME: udp6_output.c,v 1.31 2001/05/21 16:39:15 jinmei Exp $
 */

/*-
 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
 *      The Regents of the University of California.
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 "opt_inet.h"
#include "opt_inet6.h"
#include "opt_ipsec.h"
#include "opt_rss.h"

#include <sys/param.h>
#include <sys/domain.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mbuf.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/sdt.h>
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/systm.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/rss_config.h>

#include <netinet/in.h>
#include <netinet/in_kdtrace.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/udplite.h>

#include <netinet6/ip6_var.h>
#include <netinet6/in6_fib.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/in6_rss.h>
#include <netinet6/udp6_var.h>
#include <netinet6/scope6_var.h>

#include <netipsec/ipsec_support.h>

#include <security/mac/mac_framework.h>

VNET_DEFINE(int, zero_checksum_port) = 0;
#define V_zero_checksum_port    VNET(zero_checksum_port)
SYSCTL_INT(_net_inet6_udp6, OID_AUTO, rfc6935_port, CTLFLAG_VNET | CTLFLAG_RW,
    &VNET_NAME(zero_checksum_port), 0,
    "Zero UDP checksum allowed for traffic to/from this port.");

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */

static void             udp6_detach(struct socket *so);

static int
udp6_append(struct inpcb *inp, struct mbuf *n, int off,
    struct sockaddr_in6 *fromsa)
{
        struct socket *so;
        struct mbuf *opts = NULL, *tmp_opts;
        struct udpcb *up;

        INP_LOCK_ASSERT(inp);

        /*
         * Engage the tunneling protocol.
         */
        up = intoudpcb(inp);
        if (up->u_tun_func != NULL) {
                bool filtered;

                in_pcbref(inp);
                INP_RUNLOCK(inp);
                filtered = (*up->u_tun_func)(n, off, inp,
                    (struct sockaddr *)&fromsa[0], up->u_tun_ctx);
                INP_RLOCK(inp);
                if (in_pcbrele_rlocked(inp))
                        return (1);
                if (filtered) {
                        INP_RUNLOCK(inp);
                        return (1);
                }
        }

        off += sizeof(struct udphdr);

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
        /* Check AH/ESP integrity. */
        if (IPSEC_ENABLED(ipv6)) {
                if (IPSEC_CHECK_POLICY(ipv6, n, inp) != 0) {
                        m_freem(n);
                        return (0);
                }

                /* IPSec UDP encaps. */
                if ((up->u_flags & UF_ESPINUDP) != 0 &&
                    UDPENCAP_INPUT(ipv6, n, off, AF_INET6) != 0) {
                        return (0); /* Consumed. */
                }
        }
#endif /* IPSEC */
#ifdef MAC
        if (mac_inpcb_check_deliver(inp, n) != 0) {
                m_freem(n);
                return (0);
        }
#endif
        opts = NULL;
        if (inp->inp_flags & INP_CONTROLOPTS ||
            inp->inp_socket->so_options & SO_TIMESTAMP)
                ip6_savecontrol(inp, n, &opts);
        if ((inp->inp_vflag & INP_IPV6) && (inp->inp_flags2 & INP_ORIGDSTADDR)) {
                tmp_opts = sbcreatecontrol(&fromsa[1],
                    sizeof(struct sockaddr_in6), IPV6_ORIGDSTADDR,
                    IPPROTO_IPV6, M_NOWAIT);
                if (tmp_opts) {
                        if (opts) {
                                tmp_opts->m_next = opts;
                                opts = tmp_opts;
                        } else
                                opts = tmp_opts;
                }
        }
        m_adj(n, off);

        so = inp->inp_socket;
        SOCKBUF_LOCK(&so->so_rcv);
        if (sbappendaddr_locked(&so->so_rcv, (struct sockaddr *)&fromsa[0], n,
            opts) == 0) {
                soroverflow_locked(so);
                m_freem(n);
                if (opts)
                        m_freem(opts);
                UDPSTAT_INC(udps_fullsock);
        } else
                sorwakeup_locked(so);
        return (0);
}

struct udp6_multi_match_ctx {
        struct ip6_hdr *ip6;
        struct udphdr *uh;
};

static bool
udp6_multi_match(const struct inpcb *inp, void *v)
{
        struct udp6_multi_match_ctx *ctx = v;

        if ((inp->inp_vflag & INP_IPV6) == 0)
                return(false);
        if (inp->inp_lport != ctx->uh->uh_dport)
                return(false);
        if (inp->inp_fport != 0 && inp->inp_fport != ctx->uh->uh_sport)
                return(false);
        if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) &&
            !IN6_ARE_ADDR_EQUAL(&inp->in6p_laddr, &ctx->ip6->ip6_dst))
                return (false);
        if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
            (!IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &ctx->ip6->ip6_src) ||
            inp->inp_fport != ctx->uh->uh_sport))
                return (false);

        return (true);
}

static int
udp6_multi_input(struct mbuf *m, int off, int proto,
    struct sockaddr_in6 *fromsa)
{
        struct udp6_multi_match_ctx ctx;
        struct inpcb_iterator inpi = INP_ITERATOR(udp_get_inpcbinfo(proto),
            INPLOOKUP_RLOCKPCB, udp6_multi_match, &ctx);
        struct inpcb *inp;
        struct ip6_moptions *imo;
        struct mbuf *n;
        int appends = 0;

        /*
         * In the event that laddr should be set to the link-local
         * address (this happens in RIPng), the multicast address
         * specified in the received packet will not match laddr.  To
         * handle this situation, matching is relaxed if the
         * receiving interface is the same as one specified in the
         * socket and if the destination multicast address matches
         * one of the multicast groups specified in the socket.
         */

        /*
         * KAME note: traditionally we dropped udpiphdr from mbuf
         * here.  We need udphdr for IPsec processing so we do that
         * later.
         */
        ctx.ip6 = mtod(m, struct ip6_hdr *);
        ctx.uh = (struct udphdr *)((char *)ctx.ip6 + off);
        while ((inp = inp_next(&inpi)) != NULL) {
                INP_RLOCK_ASSERT(inp);
                /*
                 * XXXRW: Because we weren't holding either the inpcb
                 * or the hash lock when we checked for a match
                 * before, we should probably recheck now that the
                 * inpcb lock is (supposed to be) held.
                 */
                /*
                 * Handle socket delivery policy for any-source
                 * and source-specific multicast. [RFC3678]
                 */
                if ((imo = inp->in6p_moptions) != NULL) {
                        struct sockaddr_in6      mcaddr;
                        int                      blocked;

                        bzero(&mcaddr, sizeof(struct sockaddr_in6));
                        mcaddr.sin6_len = sizeof(struct sockaddr_in6);
                        mcaddr.sin6_family = AF_INET6;
                        mcaddr.sin6_addr = ctx.ip6->ip6_dst;

                        blocked = im6o_mc_filter(imo, m->m_pkthdr.rcvif,
                                (struct sockaddr *)&mcaddr,
                                (struct sockaddr *)&fromsa[0]);
                        if (blocked != MCAST_PASS) {
                                if (blocked == MCAST_NOTGMEMBER)
                                        IP6STAT_INC(ip6s_notmember);
                                if (blocked == MCAST_NOTSMEMBER ||
                                    blocked == MCAST_MUTED)
                                        UDPSTAT_INC(udps_filtermcast);
                                continue;
                        }
                }
                if ((n = m_copym(m, 0, M_COPYALL, M_NOWAIT)) != NULL) {
                        if (proto == IPPROTO_UDPLITE)
                                UDPLITE_PROBE(receive, NULL, inp, ctx.ip6,
                                    inp, ctx.uh);
                        else
                                UDP_PROBE(receive, NULL, inp, ctx.ip6, inp,
                                    ctx.uh);
                        if (udp6_append(inp, n, off, fromsa)) {
                                break;
                        } else
                                appends++;
                }
                /*
                 * Don't look for additional matches if this one does
                 * not have either the SO_REUSEPORT or SO_REUSEADDR
                 * socket options set.  This heuristic avoids
                 * searching through all pcbs in the common case of a
                 * non-shared port.  It assumes that an application
                 * will never clear these options after setting them.
                 */
                if ((inp->inp_socket->so_options &
                     (SO_REUSEPORT|SO_REUSEPORT_LB|SO_REUSEADDR)) == 0) {
                        INP_RUNLOCK(inp);
                        break;
                }
        }
        m_freem(m);

        if (appends == 0) {
                /*
                 * No matching pcb found; discard datagram.  (No need
                 * to send an ICMP Port Unreachable for a broadcast
                 * or multicast datagram.)
                 */
                UDPSTAT_INC(udps_noport);
                UDPSTAT_INC(udps_noportmcast);
        }

        return (IPPROTO_DONE);
}

int
udp6_input(struct mbuf **mp, int *offp, int proto)
{
        struct mbuf *m = *mp;
        struct ip6_hdr *ip6;
        struct udphdr *uh;
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;
        struct udpcb *up;
        int off = *offp;
        int cscov_partial;
        int plen, ulen;
        int lookupflags;
        struct sockaddr_in6 fromsa[2];
        struct m_tag *fwd_tag;
        uint16_t uh_sum;
        uint8_t nxt;

        NET_EPOCH_ASSERT();

        if (m->m_len < off + sizeof(struct udphdr)) {
                m = m_pullup(m, off + sizeof(struct udphdr));
                if (m == NULL) {
                        IP6STAT_INC(ip6s_exthdrtoolong);
                        *mp = NULL;
                        return (IPPROTO_DONE);
                }
        }
        ip6 = mtod(m, struct ip6_hdr *);
        uh = (struct udphdr *)((caddr_t)ip6 + off);

        UDPSTAT_INC(udps_ipackets);

        /*
         * Destination port of 0 is illegal, based on RFC768.
         */
        if (uh->uh_dport == 0)
                goto badunlocked;

        plen = ntohs(ip6->ip6_plen) - off + sizeof(*ip6);
        ulen = ntohs((u_short)uh->uh_ulen);

        nxt = proto;
        cscov_partial = (nxt == IPPROTO_UDPLITE) ? 1 : 0;
        if (nxt == IPPROTO_UDPLITE) {
                /* Zero means checksum over the complete packet. */
                if (ulen == 0)
                        ulen = plen;
                if (ulen == plen)
                        cscov_partial = 0;
                if ((ulen < sizeof(struct udphdr)) || (ulen > plen)) {
                        /* XXX: What is the right UDPLite MIB counter? */
                        goto badunlocked;
                }
                if (uh->uh_sum == 0) {
                        /* XXX: What is the right UDPLite MIB counter? */
                        goto badunlocked;
                }
        } else {
                if ((ulen < sizeof(struct udphdr)) || (plen != ulen)) {
                        UDPSTAT_INC(udps_badlen);
                        goto badunlocked;
                }
                if (uh->uh_sum == 0) {
                        UDPSTAT_INC(udps_nosum);
                        /*
                         * dport 0 was rejected earlier so this is OK even if
                         * zero_checksum_port is 0 (which is its default value).
                         */
                        if (ntohs(uh->uh_dport) == V_zero_checksum_port)
                                goto skip_checksum;
                        else
                                goto badunlocked;
                }
        }

        if ((m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) &&
            !cscov_partial) {
                if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
                        uh_sum = m->m_pkthdr.csum_data;
                else
                        uh_sum = in6_cksum_pseudo(ip6, ulen, nxt,
                            m->m_pkthdr.csum_data);
                uh_sum ^= 0xffff;
        } else if (m->m_pkthdr.csum_flags & CSUM_IP6_UDP) {
                /*
                 * Packet from local host (maybe from a VM).
                 * Checksum not required.
                 */
                uh_sum = 0;
        } else
                uh_sum = in6_cksum_partial(m, nxt, off, plen, ulen);

        if (uh_sum != 0) {
                UDPSTAT_INC(udps_badsum);
                goto badunlocked;
        }

skip_checksum:
        /*
         * Construct sockaddr format source address.
         */
        init_sin6(&fromsa[0], m, 0);
        fromsa[0].sin6_port = uh->uh_sport;
        init_sin6(&fromsa[1], m, 1);
        fromsa[1].sin6_port = uh->uh_dport;

        pcbinfo = udp_get_inpcbinfo(nxt);
        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst))  {
                *mp = NULL;
                return (udp6_multi_input(m, off, proto, fromsa));
        }

        /*
         * Locate pcb for datagram.
         */
        lookupflags = INPLOOKUP_RLOCKPCB |
            (V_udp_bind_all_fibs ? 0 : INPLOOKUP_FIB);

        /*
         * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain.
         */
        if ((m->m_flags & M_IP6_NEXTHOP) &&
            (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
                struct sockaddr_in6 *next_hop6;

                next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1);

                /*
                 * Transparently forwarded. Pretend to be the destination.
                 * Already got one like this?
                 */
                inp = in6_pcblookup_mbuf(pcbinfo, &ip6->ip6_src,
                    uh->uh_sport, &ip6->ip6_dst, uh->uh_dport,
                    lookupflags, m->m_pkthdr.rcvif, m);
                if (!inp) {
                        /*
                         * It's new.  Try to find the ambushing socket.
                         * Because we've rewritten the destination address,
                         * any hardware-generated hash is ignored.
                         */
                        inp = in6_pcblookup(pcbinfo, &ip6->ip6_src,
                            uh->uh_sport, &next_hop6->sin6_addr,
                            next_hop6->sin6_port ? htons(next_hop6->sin6_port) :
                            uh->uh_dport, INPLOOKUP_WILDCARD | lookupflags,
                            m->m_pkthdr.rcvif);
                }
                /* Remove the tag from the packet. We don't need it anymore. */
                m_tag_delete(m, fwd_tag);
                m->m_flags &= ~M_IP6_NEXTHOP;
        } else
                inp = in6_pcblookup_mbuf(pcbinfo, &ip6->ip6_src,
                    uh->uh_sport, &ip6->ip6_dst, uh->uh_dport,
                    INPLOOKUP_WILDCARD | lookupflags,
                    m->m_pkthdr.rcvif, m);
        if (inp == NULL) {
                if (V_udp_log_in_vain) {
                        char ip6bufs[INET6_ADDRSTRLEN];
                        char ip6bufd[INET6_ADDRSTRLEN];

                        log(LOG_INFO,
                            "Connection attempt to UDP [%s]:%d from [%s]:%d\n",
                            ip6_sprintf(ip6bufd, &ip6->ip6_dst),
                            ntohs(uh->uh_dport),
                            ip6_sprintf(ip6bufs, &ip6->ip6_src),
                            ntohs(uh->uh_sport));
                }
                if (nxt == IPPROTO_UDPLITE)
                        UDPLITE_PROBE(receive, NULL, NULL, ip6, NULL, uh);
                else
                        UDP_PROBE(receive, NULL, NULL, ip6, NULL, uh);
                UDPSTAT_INC(udps_noport);
                if (m->m_flags & M_MCAST) {
                        printf("UDP6: M_MCAST is set in a unicast packet.\n");
                        UDPSTAT_INC(udps_noportmcast);
                        goto badunlocked;
                }
                if (V_udp_blackhole && (V_udp_blackhole_local ||
                    !in6_localip(&ip6->ip6_src)))
                        goto badunlocked;
                icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOPORT, 0);
                *mp = NULL;
                return (IPPROTO_DONE);
        }
        INP_RLOCK_ASSERT(inp);
        up = intoudpcb(inp);
        if (cscov_partial) {
                if (up->u_rxcslen == 0 || up->u_rxcslen > ulen) {
                        INP_RUNLOCK(inp);
                        m_freem(m);
                        *mp = NULL;
                        return (IPPROTO_DONE);
                }
        }
        if (nxt == IPPROTO_UDPLITE)
                UDPLITE_PROBE(receive, NULL, inp, ip6, inp, uh);
        else
                UDP_PROBE(receive, NULL, inp, ip6, inp, uh);
        if (udp6_append(inp, m, off, fromsa) == 0)
                INP_RUNLOCK(inp);
        *mp = NULL;
        return (IPPROTO_DONE);

badunlocked:
        m_freem(m);
        *mp = NULL;
        return (IPPROTO_DONE);
}

static void
udp6_common_ctlinput(struct ip6ctlparam *ip6cp, struct inpcbinfo *pcbinfo)
{
        struct udphdr uh;
        struct ip6_hdr *ip6;
        struct mbuf *m;
        struct inpcb *inp;
        int errno, off = 0;
        struct udp_portonly {
                u_int16_t uh_sport;
                u_int16_t uh_dport;
        } *uhp;

        if ((errno = icmp6_errmap(ip6cp->ip6c_icmp6)) == 0)
                return;

        m = ip6cp->ip6c_m;
        ip6 = ip6cp->ip6c_ip6;
        off = ip6cp->ip6c_off;

        /* Check if we can safely examine src and dst ports. */
        if (m->m_pkthdr.len < off + sizeof(*uhp))
                return;

        bzero(&uh, sizeof(uh));
        m_copydata(m, off, sizeof(*uhp), (caddr_t)&uh);

        /* Check to see if its tunneled */
        inp = in6_pcblookup_mbuf(pcbinfo, &ip6->ip6_dst, uh.uh_dport,
            &ip6->ip6_src, uh.uh_sport, INPLOOKUP_WILDCARD | INPLOOKUP_RLOCKPCB,
            m->m_pkthdr.rcvif, m);
        if (inp != NULL) {
                struct udpcb *up;
                udp_tun_icmp_t *func;

                up = intoudpcb(inp);
                func = up->u_icmp_func;
                INP_RUNLOCK(inp);
                if (func != NULL)
                        func(ip6cp);
        }
        in6_pcbnotify(pcbinfo, ip6cp->ip6c_finaldst, uh.uh_dport,
            ip6cp->ip6c_src, uh.uh_sport, errno, ip6cp->ip6c_cmdarg,
            udp_notify);
}

static void
udp6_ctlinput(struct ip6ctlparam *ctl)
{

        return (udp6_common_ctlinput(ctl, &V_udbinfo));
}

static void
udplite6_ctlinput(struct ip6ctlparam *ctl)
{

        return (udp6_common_ctlinput(ctl, &V_ulitecbinfo));
}

static int
udp6_getcred(SYSCTL_HANDLER_ARGS)
{
        struct xucred xuc;
        struct sockaddr_in6 addrs[2];
        struct epoch_tracker et;
        struct inpcb *inp;
        int error;

        if (req->newptr == NULL)
                return (EINVAL);
        error = priv_check(req->td, PRIV_NETINET_GETCRED);
        if (error)
                return (error);

        if (req->newlen != sizeof(addrs))
                return (EINVAL);
        if (req->oldlen != sizeof(struct xucred))
                return (EINVAL);
        error = SYSCTL_IN(req, addrs, sizeof(addrs));
        if (error)
                return (error);
        if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 ||
            (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) {
                return (error);
        }
        NET_EPOCH_ENTER(et);
        inp = in6_pcblookup(&V_udbinfo, &addrs[1].sin6_addr,
            addrs[1].sin6_port, &addrs[0].sin6_addr, addrs[0].sin6_port,
            INPLOOKUP_WILDCARD | INPLOOKUP_RLOCKPCB, NULL);
        NET_EPOCH_EXIT(et);
        if (inp != NULL) {
                INP_RLOCK_ASSERT(inp);
                if (inp->inp_socket == NULL)
                        error = ENOENT;
                if (error == 0)
                        error = cr_canseesocket(req->td->td_ucred,
                            inp->inp_socket);
                if (error == 0)
                        cru2x(inp->inp_cred, &xuc);
                INP_RUNLOCK(inp);
        } else
                error = ENOENT;
        if (error == 0)
                error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
        return (error);
}

SYSCTL_PROC(_net_inet6_udp6, OID_AUTO, getcred,
    CTLTYPE_OPAQUE | CTLFLAG_RW | CTLFLAG_MPSAFE,
    0, 0, udp6_getcred, "S,xucred",
    "Get the xucred of a UDP6 connection");

static int
udp6_send(struct socket *so, int flags_arg, struct mbuf *m,
    struct sockaddr *addr6, struct mbuf *control, struct thread *td)
{
        struct inpcb *inp;
        struct ip6_hdr *ip6;
        struct udphdr *udp6;
        struct in6_addr *laddr, *faddr, in6a;
        struct ip6_pktopts *optp, opt;
        struct sockaddr_in6 *sin6, tmp;
        struct epoch_tracker et;
        int cscov_partial, error, flags, hlen, scope_ambiguous;
        u_int32_t ulen, plen;
        uint16_t cscov;
        u_short fport;
        uint8_t nxt;

        if (addr6) {
                error = 0;
                if (addr6->sa_family != AF_INET6)
                        error = EAFNOSUPPORT;
                else if (addr6->sa_len != sizeof(struct sockaddr_in6))
                        error = EINVAL;
                if (__predict_false(error != 0)) {
                        m_freem(control);
                        m_freem(m);
                        return (error);
                }
        }

        sin6 = (struct sockaddr_in6 *)addr6;

        scope_ambiguous = 0;
        if (sin6) {
                /* Protect *addr6 from overwrites. */
                tmp = *sin6;
                sin6 = &tmp;

                /*
                 * Application should provide a proper zone ID or the use of
                 * default zone IDs should be enabled.  Unfortunately, some
                 * applications do not behave as it should, so we need a
                 * workaround.  Even if an appropriate ID is not determined,
                 * we'll see if we can determine the outgoing interface.  If we
                 * can, determine the zone ID based on the interface below.
                 */
                if (sin6->sin6_scope_id == 0 && !V_ip6_use_defzone)
                        scope_ambiguous = 1;
                if ((error = sa6_embedscope(sin6, V_ip6_use_defzone)) != 0) {
                        if (control)
                                m_freem(control);
                        m_freem(m);
                        return (error);
                }
        }

        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
        /*
         * In the following cases we want a write lock on the inp for either
         * local operations or for possible route cache updates in the IPv6
         * output path:
         * - on connected sockets (sin6 is NULL) for route cache updates,
         * - when we are not bound to an address and source port (it is
         *   in6_pcbsetport() which will require the write lock).
         *
         * We check the inp fields before actually locking the inp, so
         * here exists a race, and we may WLOCK the inp and end with already
         * bound one by other thread. This is fine.
         */
        if (sin6 == NULL || (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) &&
            inp->inp_lport == 0))
                INP_WLOCK(inp);
        else
                INP_RLOCK(inp);

        nxt = (inp->inp_socket->so_proto->pr_protocol == IPPROTO_UDP) ?
            IPPROTO_UDP : IPPROTO_UDPLITE;

#ifdef INET
        if ((inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
                int hasv4addr;

                if (sin6 == NULL)
                        hasv4addr = (inp->inp_vflag & INP_IPV4);
                else
                        hasv4addr = IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)
                            ? 1 : 0;
                if (hasv4addr) {
                        /*
                         * XXXRW: We release UDP-layer locks before calling
                         * udp_send() in order to avoid recursion.  However,
                         * this does mean there is a short window where inp's
                         * fields are unstable.  Could this lead to a
                         * potential race in which the factors causing us to
                         * select the UDPv4 output routine are invalidated?
                         */
                        INP_UNLOCK(inp);
                        if (sin6)
                                in6_sin6_2_sin_in_sock((struct sockaddr *)sin6);
                        /* addr will just be freed in sendit(). */
                        return (udp_send(so, flags_arg | PRUS_IPV6, m,
                            (struct sockaddr *)sin6, control, td));
                }
        } else
#endif
        if (sin6 && IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
                /*
                 * Given this is either an IPv6-only socket or no INET is
                 * supported we will fail the send if the given destination
                 * address is a v4mapped address.
                 */
                INP_UNLOCK(inp);
                m_freem(m);
                m_freem(control);
                return (EINVAL);
        }

        NET_EPOCH_ENTER(et);
        if (control) {
                if ((error = ip6_setpktopts(control, &opt,
                    inp->in6p_outputopts, td->td_ucred, nxt)) != 0) {
                        goto release;
                }
                optp = &opt;
        } else
                optp = inp->in6p_outputopts;

        if (sin6) {
                /*
                 * Since we saw no essential reason for calling in_pcbconnect,
                 * we get rid of such kind of logic, and call in6_selectsrc
                 * and in6_pcbsetport in order to fill in the local address
                 * and the local port.
                 */
                if (sin6->sin6_port == 0) {
                        error = EADDRNOTAVAIL;
                        goto release;
                }

                if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                        /* how about ::ffff:0.0.0.0 case? */
                        error = EISCONN;
                        goto release;
                }

                /*
                 * Given we handle the v4mapped case in the INET block above
                 * assert here that it must not happen anymore.
                 */
                KASSERT(!IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr),
                    ("%s: sin6(%p)->sin6_addr is v4mapped which we "
                    "should have handled.", __func__, sin6));

                /* This only requires read-locking. */
                error = in6_selectsrc_socket(sin6, optp, inp,
                    td->td_ucred, scope_ambiguous, &in6a, NULL);
                if (error)
                        goto release;
                laddr = &in6a;

                if (inp->inp_lport == 0) {
                        struct inpcbinfo *pcbinfo;

                        INP_WLOCK_ASSERT(inp);

                        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
                        INP_HASH_WLOCK(pcbinfo);
                        error = in6_pcbsetport(laddr, inp, td->td_ucred);
                        INP_HASH_WUNLOCK(pcbinfo);
                        if (error != 0) {
                                /* Undo an address bind that may have occurred. */
                                inp->in6p_laddr = in6addr_any;
                                goto release;
                        }
                }
                faddr = &sin6->sin6_addr;
                fport = sin6->sin6_port; /* allow 0 port */

        } else {
                if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                        error = ENOTCONN;
                        goto release;
                }
                laddr = &inp->in6p_laddr;
                faddr = &inp->in6p_faddr;
                fport = inp->inp_fport;
        }


        /*
         * We do not support IPv6 Jumbograms (RFC2675), so validate the payload
         * length fits in a normal gram.
         */
        ulen = m->m_pkthdr.len;
        plen = sizeof(struct udphdr) + ulen;
        hlen = sizeof(struct ip6_hdr);

        if (plen > IPV6_MAXPAYLOAD) {
                m_freem(control);
                m_freem(m);
                return (EMSGSIZE);
        }

        /*
         * Calculate data length and get a mbuf for UDP, IP6, and possible
         * link-layer headers.  Immediate slide the data pointer back forward
         * since we won't use that space at this layer.
         */
        M_PREPEND(m, hlen + sizeof(struct udphdr) + max_linkhdr, M_NOWAIT);
        if (m == NULL) {
                error = ENOBUFS;
                goto release;
        }
        m->m_data += max_linkhdr;
        m->m_len -= max_linkhdr;
        m->m_pkthdr.len -= max_linkhdr;

        /*
         * Stuff checksum and output datagram.
         */
        cscov = cscov_partial = 0;
        udp6 = (struct udphdr *)(mtod(m, caddr_t) + hlen);
        udp6->uh_sport = inp->inp_lport; /* lport is always set in the PCB */
        udp6->uh_dport = fport;
        if (nxt == IPPROTO_UDPLITE) {
                struct udpcb *up;

                up = intoudpcb(inp);
                cscov = up->u_txcslen;
                if (cscov >= plen)
                        cscov = 0;
                udp6->uh_ulen = htons(cscov);
                /*
                 * For UDP-Lite, checksum coverage length of zero means
                 * the entire UDPLite packet is covered by the checksum.
                 */
                cscov_partial = (cscov == 0) ? 0 : 1;
        } else {
                MPASS(plen <= IPV6_MAXPAYLOAD);
                udp6->uh_ulen = htons((u_short)plen);
        }
        udp6->uh_sum = 0;

        ip6 = mtod(m, struct ip6_hdr *);
        ip6->ip6_flow   = inp->inp_flow & IPV6_FLOWINFO_MASK;
        ip6->ip6_vfc    &= ~IPV6_VERSION_MASK;
        ip6->ip6_vfc    |= IPV6_VERSION;
        ip6->ip6_plen   = htons((u_short)plen);
        ip6->ip6_nxt    = nxt;
        ip6->ip6_hlim   = in6_selecthlim(inp, NULL);
        ip6->ip6_src    = *laddr;
        ip6->ip6_dst    = *faddr;

#ifdef MAC
        mac_inpcb_create_mbuf(inp, m);
#endif

        if (cscov_partial) {
                if ((udp6->uh_sum = in6_cksum_partial(m, nxt,
                    sizeof(struct ip6_hdr), plen, cscov)) == 0)
                        udp6->uh_sum = 0xffff;
        } else {
                udp6->uh_sum = in6_cksum_pseudo(ip6, plen, nxt, 0);
                m->m_pkthdr.csum_flags = CSUM_UDP_IPV6;
                m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
        }

        flags = 0;
        if (CALC_FLOWID_OUTBOUND_SENDTO) {
                uint32_t hash_type, hash_val;
                uint8_t pr;

                pr = inp->inp_socket->so_proto->pr_protocol;

                hash_val = fib6_calc_packet_hash(laddr, faddr,
                    inp->inp_lport, fport, pr, &hash_type);
                m->m_pkthdr.flowid = hash_val;
                M_HASHTYPE_SET(m, hash_type);
        }
        /* do not use inp flowid */
        flags |= IP_NODEFAULTFLOWID;

        UDPSTAT_INC(udps_opackets);
        if (nxt == IPPROTO_UDPLITE)
                UDPLITE_PROBE(send, NULL, inp, ip6, inp, udp6);
        else
                UDP_PROBE(send, NULL, inp, ip6, inp, udp6);
        error = ip6_output(m, optp,
            INP_WLOCKED(inp) ? &inp->inp_route6 : NULL, flags,
            inp->in6p_moptions, NULL, inp);
        INP_UNLOCK(inp);
        NET_EPOCH_EXIT(et);

        if (control) {
                ip6_clearpktopts(&opt, -1);
                m_freem(control);
        }
        return (error);

release:
        INP_UNLOCK(inp);
        NET_EPOCH_EXIT(et);
        if (control) {
                ip6_clearpktopts(&opt, -1);
                m_freem(control);
        }
        m_freem(m);

        return (error);
}

static void
udp6_abort(struct socket *so)
{
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp6_abort: inp == NULL"));

        INP_WLOCK(inp);
#ifdef INET
        if (inp->inp_vflag & INP_IPV4) {
                INP_WUNLOCK(inp);
                udp_abort(so);
                return;
        }
#endif

        if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                INP_HASH_WLOCK(pcbinfo);
                in6_pcbdisconnect(inp);
                INP_HASH_WUNLOCK(pcbinfo);
                soisdisconnected(so);
        }
        INP_WUNLOCK(inp);
}

static int
udp6_attach(struct socket *so, int proto, struct thread *td)
{
        struct inpcbinfo *pcbinfo;
        struct inpcb *inp;
        struct udpcb *up;
        int error;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp == NULL, ("udp6_attach: inp != NULL"));

        if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
                error = soreserve(so, udp_sendspace, udp_recvspace);
                if (error)
                        return (error);
        }
        error = in_pcballoc(so, pcbinfo);
        if (error)
                return (error);
        inp = (struct inpcb *)so->so_pcb;
        inp->in6p_cksum = -1;   /* just to be sure */
        /*
         * XXX: ugly!!
         * IPv4 TTL initialization is necessary for an IPv6 socket as well,
         * because the socket may be bound to an IPv6 wildcard address,
         * which may match an IPv4-mapped IPv6 address.
         */
        inp->inp_ip_ttl = V_ip_defttl;
        up = intoudpcb(inp);
        bzero(&up->u_start_zero, u_zero_size);
        INP_WUNLOCK(inp);
        return (0);
}

static int
udp6_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
{
        struct sockaddr_in6 *sin6_p;
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;
        int error;
        u_char vflagsav;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp6_bind: inp == NULL"));

        if (nam->sa_family != AF_INET6)
                return (EAFNOSUPPORT);
        if (nam->sa_len != sizeof(struct sockaddr_in6))
                return (EINVAL);

        sin6_p = (struct sockaddr_in6 *)nam;

        INP_WLOCK(inp);
        INP_HASH_WLOCK(pcbinfo);
        vflagsav = inp->inp_vflag;
        inp->inp_vflag &= ~INP_IPV4;
        inp->inp_vflag |= INP_IPV6;
        if ((inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
                if (IN6_IS_ADDR_UNSPECIFIED(&sin6_p->sin6_addr))
                        inp->inp_vflag |= INP_IPV4;
#ifdef INET
                else if (IN6_IS_ADDR_V4MAPPED(&sin6_p->sin6_addr)) {
                        struct sockaddr_in sin;

                        in6_sin6_2_sin(&sin, sin6_p);
                        inp->inp_vflag |= INP_IPV4;
                        inp->inp_vflag &= ~INP_IPV6;
                        error = in_pcbbind(inp, &sin,
                            V_udp_bind_all_fibs ? 0 : INPBIND_FIB,
                            td->td_ucred);
                        goto out;
                }
#endif
        }

        error = in6_pcbbind(inp, sin6_p, V_udp_bind_all_fibs ? 0 : INPBIND_FIB,
            td->td_ucred);
#ifdef INET
out:
#endif
        if (error != 0)
                inp->inp_vflag = vflagsav;
        INP_HASH_WUNLOCK(pcbinfo);
        INP_WUNLOCK(inp);
        return (error);
}

static void
udp6_close(struct socket *so)
{
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp6_close: inp == NULL"));

        INP_WLOCK(inp);
#ifdef INET
        if (inp->inp_vflag & INP_IPV4) {
                INP_WUNLOCK(inp);
                (void)udp_disconnect(so);
                return;
        }
#endif
        if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                INP_HASH_WLOCK(pcbinfo);
                in6_pcbdisconnect(inp);
                INP_HASH_WUNLOCK(pcbinfo);
                soisdisconnected(so);
        }
        INP_WUNLOCK(inp);
}

static int
udp6_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
{
        struct epoch_tracker et;
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;
        struct sockaddr_in6 *sin6;
        int error;
        u_char vflagsav;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp6_connect: inp == NULL"));

        sin6 = (struct sockaddr_in6 *)nam;
        if (sin6->sin6_family != AF_INET6)
                return (EAFNOSUPPORT);
        if (sin6->sin6_len != sizeof(*sin6))
                return (EINVAL);

        /*
         * XXXRW: Need to clarify locking of v4/v6 flags.
         */
        INP_WLOCK(inp);
#ifdef INET
        if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
                struct sockaddr_in sin;

                if ((inp->inp_flags & IN6P_IPV6_V6ONLY) != 0) {
                        error = EINVAL;
                        goto out;
                }
                if ((inp->inp_vflag & INP_IPV4) == 0) {
                        error = EAFNOSUPPORT;
                        goto out;
                }
                if (inp->inp_faddr.s_addr != INADDR_ANY) {
                        error = EISCONN;
                        goto out;
                }
                in6_sin6_2_sin(&sin, sin6);
                error = prison_remote_ip4(td->td_ucred, &sin.sin_addr);
                if (error != 0)
                        goto out;
                vflagsav = inp->inp_vflag;
                inp->inp_vflag |= INP_IPV4;
                inp->inp_vflag &= ~INP_IPV6;
                NET_EPOCH_ENTER(et);
                INP_HASH_WLOCK(pcbinfo);
                error = in_pcbconnect(inp, &sin, td->td_ucred);
                INP_HASH_WUNLOCK(pcbinfo);
                NET_EPOCH_EXIT(et);
                /*
                 * If connect succeeds, mark socket as connected. If
                 * connect fails and socket is unbound, reset inp_vflag
                 * field.
                 */
                if (error == 0)
                        soisconnected(so);
                else if (inp->inp_laddr.s_addr == INADDR_ANY &&
                    inp->inp_lport == 0)
                        inp->inp_vflag = vflagsav;
                goto out;
        } else {
                if ((inp->inp_vflag & INP_IPV6) == 0) {
                        error = EAFNOSUPPORT;
                        goto out;
                }
        }
#endif
        if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                error = EISCONN;
                goto out;
        }
        error = prison_remote_ip6(td->td_ucred, &sin6->sin6_addr);
        if (error != 0)
                goto out;
        vflagsav = inp->inp_vflag;
        inp->inp_vflag &= ~INP_IPV4;
        inp->inp_vflag |= INP_IPV6;
        NET_EPOCH_ENTER(et);
        INP_HASH_WLOCK(pcbinfo);
        error = in6_pcbconnect(inp, sin6, td->td_ucred, true);
        INP_HASH_WUNLOCK(pcbinfo);
        NET_EPOCH_EXIT(et);
        /*
         * If connect succeeds, mark socket as connected. If
         * connect fails and socket is unbound, reset inp_vflag
         * field.
         */
        if (error == 0)
                soisconnected(so);
        else if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) &&
            inp->inp_lport == 0)
                inp->inp_vflag = vflagsav;
out:
        INP_WUNLOCK(inp);
        return (error);
}

static void
udp6_detach(struct socket *so)
{
        struct inpcb *inp;

        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp6_detach: inp == NULL"));

        INP_WLOCK(inp);
        in_pcbfree(inp);
}

static int
udp6_disconnect(struct socket *so)
{
        struct inpcb *inp;
        struct inpcbinfo *pcbinfo;

        pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
        inp = sotoinpcb(so);
        KASSERT(inp != NULL, ("udp6_disconnect: inp == NULL"));

        INP_WLOCK(inp);
#ifdef INET
        if (inp->inp_vflag & INP_IPV4) {
                INP_WUNLOCK(inp);
                (void)udp_disconnect(so);
                return (0);
        }
#endif

        if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                INP_WUNLOCK(inp);
                return (ENOTCONN);
        }

        INP_HASH_WLOCK(pcbinfo);
        in6_pcbdisconnect(inp);
        INP_HASH_WUNLOCK(pcbinfo);
        SOCK_LOCK(so);
        so->so_state &= ~SS_ISCONNECTED;                /* XXX */
        SOCK_UNLOCK(so);
        INP_WUNLOCK(inp);
        return (0);
}

#define UDP6_PROTOSW                                                    \
        .pr_type =              SOCK_DGRAM,                             \
        .pr_flags =             PR_ATOMIC|PR_ADDR|PR_CAPATTACH,         \
        .pr_ctloutput =         udp_ctloutput,                          \
        .pr_abort =             udp6_abort,                             \
        .pr_attach =            udp6_attach,                            \
        .pr_bind =              udp6_bind,                              \
        .pr_connect =           udp6_connect,                           \
        .pr_control =           in6_control,                            \
        .pr_detach =            udp6_detach,                            \
        .pr_disconnect =        udp6_disconnect,                        \
        .pr_peeraddr =          in6_mapped_peeraddr,                    \
        .pr_send =              udp6_send,                              \
        .pr_shutdown =          udp_shutdown,                           \
        .pr_sockaddr =          in6_mapped_sockaddr,                    \
        .pr_soreceive =         soreceive_dgram,                        \
        .pr_sosend =            sosend_dgram,                           \
        .pr_sosetlabel =        in_pcbsosetlabel,                       \
        .pr_close =             udp6_close

struct protosw udp6_protosw = {
        .pr_protocol =          IPPROTO_UDP,
        UDP6_PROTOSW
};

struct protosw udplite6_protosw = {
        .pr_protocol =          IPPROTO_UDPLITE,
        UDP6_PROTOSW
};

static void
udp6_init(void *arg __unused)
{

        IP6PROTO_REGISTER(IPPROTO_UDP, udp6_input, udp6_ctlinput);
        IP6PROTO_REGISTER(IPPROTO_UDPLITE, udp6_input, udplite6_ctlinput);
}
SYSINIT(udp6_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, udp6_init, NULL);