/*      $OpenBSD: portmap.c,v 1.51 2023/03/08 04:43:14 guenther Exp $   */

/*-
 * Copyright (c) 1996, 1997 Theo de Raadt (OpenBSD). All rights reserved.
 * Copyright (c) 1990 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.
 */
/*
 * Copyright (c) 2010, Oracle America, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the "Oracle America, Inc." 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 COPYRIGHT HOLDERS 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
 *   COPYRIGHT HOLDER 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.
 */

/*
 * portmap.c, Implements the program,version to port number mapping for
 * rpc.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/resource.h>

#include <rpcsvc/nfs_prot.h>
#include <arpa/inet.h>
#include <rpc/rpc.h>
#include <rpc/pmap_prot.h>

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <netdb.h>
#include <pwd.h>
#include <errno.h>
#include <err.h>

void reg_service(struct svc_req *, SVCXPRT *);
void reap(int);
void callit(struct svc_req *, SVCXPRT *);
int check_callit(struct sockaddr_in *, u_long, u_long);
struct pmaplist *find_service(u_long, u_long, u_long);

struct pmaplist *pmaplist;
int debugging;

SVCXPRT *ludpxprt, *ltcpxprt;

int
main(int argc, char *argv[])
{
        int sock, lsock, c, on = 1;
        socklen_t len = sizeof(struct sockaddr_in);
        struct sockaddr_in addr, laddr;
        struct pmaplist *pml;
        struct passwd *pw;
        SVCXPRT *xprt;

        while ((c = getopt(argc, argv, "d")) != -1) {
                switch (c) {
                case 'd':
                        debugging = 1;
                        break;
                default:
                        (void)fprintf(stderr, "usage: %s [-d]\n", argv[0]);
                        exit(1);
                }
        }

        if (!debugging && daemon(0, 0)) {
                (void)fprintf(stderr, "portmap: fork: %s", strerror(errno));
                exit(1);
        }

        openlog("portmap", LOG_NDELAY | (debugging ? LOG_PID | LOG_PERROR :
            LOG_PID), LOG_DAEMON);

        bzero(&addr, sizeof addr);
        addr.sin_addr.s_addr = 0;
        addr.sin_family = AF_INET;
        addr.sin_addr.s_addr = htonl(INADDR_ANY);
        addr.sin_port = htons(PMAPPORT);

        bzero(&laddr, sizeof laddr);
        laddr.sin_addr.s_addr = 0;
        laddr.sin_family = AF_INET;
        laddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
        laddr.sin_port = htons(PMAPPORT);

        if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
                syslog(LOG_ERR, "cannot create udp socket: %m");
                exit(1);
        }
        setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
        if (bind(sock, (struct sockaddr *)&addr, len) == -1) {
                syslog(LOG_ERR, "cannot bind udp: %m");
                exit(1);
        }

        if ((xprt = svcudp_create(sock)) == NULL) {
                syslog(LOG_ERR, "couldn't do udp_create");
                exit(1);
        }

        if ((lsock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
                syslog(LOG_ERR, "cannot create udp socket: %m");
                exit(1);
        }
        setsockopt(lsock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
        if (bind(lsock, (struct sockaddr *)&laddr, len) == -1) {
                syslog(LOG_ERR, "cannot bind local udp: %m");
                exit(1);
        }

        if ((ludpxprt = svcudp_create(lsock)) == NULL) {
                syslog(LOG_ERR, "couldn't do udp_create");
                exit(1);
        }

        /* make an entry for ourself */
        pml = malloc(sizeof(struct pmaplist));
        if (pml == NULL) {
                syslog(LOG_ERR, "out of memory");
                exit(1);
        }
        pml->pml_next = 0;
        pml->pml_map.pm_prog = PMAPPROG;
        pml->pml_map.pm_vers = PMAPVERS;
        pml->pml_map.pm_prot = IPPROTO_UDP;
        pml->pml_map.pm_port = PMAPPORT;
        pmaplist = pml;

        if ((sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1) {
                syslog(LOG_ERR, "cannot create tcp socket: %m");
                exit(1);
        }
        setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
        if (bind(sock, (struct sockaddr *)&addr, len) == -1) {
                syslog(LOG_ERR, "cannot bind tcp: %m");
                exit(1);
        }
        if ((xprt = svctcp_create(sock, RPCSMALLMSGSIZE, RPCSMALLMSGSIZE)) ==
            NULL) {
                syslog(LOG_ERR, "couldn't do tcp_create");
                exit(1);
        }

        if ((lsock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1) {
                syslog(LOG_ERR, "cannot create tcp socket: %m");
                exit(1);
        }
        setsockopt(lsock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
        if (bind(lsock, (struct sockaddr *)&laddr, len) == -1) {
                syslog(LOG_ERR, "cannot bind tcp: %m");
                exit(1);
        }
        if ((ltcpxprt = svctcp_create(lsock, RPCSMALLMSGSIZE,
            RPCSMALLMSGSIZE)) == NULL) {
                syslog(LOG_ERR, "couldn't do tcp_create");
                exit(1);
        }

        /* make an entry for ourself */
        pml = malloc(sizeof(struct pmaplist));
        if (pml == NULL) {
                syslog(LOG_ERR, "out of memory");
                exit(1);
        }
        pml->pml_map.pm_prog = PMAPPROG;
        pml->pml_map.pm_vers = PMAPVERS;
        pml->pml_map.pm_prot = IPPROTO_TCP;
        pml->pml_map.pm_port = PMAPPORT;
        pml->pml_next = pmaplist;
        pmaplist = pml;

        if ((pw = getpwnam("_portmap")) == NULL) {
                syslog(LOG_ERR, "no such user _portmap");
                exit(1);
        }
        if (chroot("/var/empty") == -1) {
                syslog(LOG_ERR, "cannot chroot to /var/empty.");
                exit(1);
        }
        if (chdir("/") == -1) {
                syslog(LOG_ERR, "cannot chdir to new /.");
                exit(1);
        }

        if (pw) {
                if (setgroups(1, &pw->pw_gid) == -1 ||
                    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1 ||
                    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1) {
                        syslog(LOG_ERR, "revoke privs: %s", strerror(errno));
                        exit(1);
                }
        }
        endpwent();

        if (pledge("stdio inet proc", NULL) == -1)
                err(1, "pledge");

        if (svc_register(xprt, PMAPPROG, PMAPVERS, reg_service, FALSE) == 0) {
                syslog(LOG_ERR, "svc_register failed.");
                exit(1);
        }

        (void)signal(SIGCHLD, reap);
        svc_run();
        syslog(LOG_ERR, "svc_run returned unexpectedly");
        abort();
}

struct pmaplist *
find_service(u_long prog, u_long vers, u_long prot)
{
        struct pmaplist *hit = NULL;
        struct pmaplist *pml;

        for (pml = pmaplist; pml != NULL; pml = pml->pml_next) {
                if ((pml->pml_map.pm_prog != prog) ||
                    (pml->pml_map.pm_prot != prot))
                        continue;
                hit = pml;
                if (pml->pml_map.pm_vers == vers)
                        break;
        }
        return (hit);
}

/*
 * 1 OK, 0 not
 */
void
reg_service(struct svc_req *rqstp, SVCXPRT *xprt)
{
        struct pmap reg;
        struct pmaplist *pml, *prevpml, *fnd;
        struct sockaddr_in *fromsin;
        long ans = 0, port;
        void *t;

        fromsin = svc_getcaller(xprt);

        if (debugging)
                (void)fprintf(stderr, "server: about to do a switch\n");
        switch (rqstp->rq_proc) {
        case PMAPPROC_NULL:
                /*
                 * Null proc call
                 */
                if (!svc_sendreply(xprt, xdr_void, NULL) && debugging) {
                        abort();
                }
                break;
        case PMAPPROC_SET:
                /*
                 * Set a program,version to port mapping
                 */
                if (xprt != ltcpxprt && xprt != ludpxprt) {
                        syslog(LOG_WARNING,
                            "non-local set attempt (might be from %s)",
                            inet_ntoa(fromsin->sin_addr));
                        svcerr_noproc(xprt);
                        return;
                }
                if (!svc_getargs(xprt, xdr_pmap, (caddr_t)&reg)) {
                        svcerr_decode(xprt);
                        break;
                }

                /*
                 * check to see if already used
                 * find_service returns a hit even if
                 * the versions don't match, so check for it
                 */
                fnd = find_service(reg.pm_prog, reg.pm_vers, reg.pm_prot);
                if (fnd && fnd->pml_map.pm_vers == reg.pm_vers) {
                        if (fnd->pml_map.pm_port == reg.pm_port)
                                ans = 1;
                        goto done;
                }

                if (debugging)
                        printf("set: prog %lu vers %lu port %lu\n",
                            reg.pm_prog, reg.pm_vers, reg.pm_port);

                if (reg.pm_port & ~0xffff)
                        goto done;

                /*
                 * only permit localhost root to create
                 * mappings pointing at sensitive ports
                 */
                if ((reg.pm_port < IPPORT_RESERVED ||
                    reg.pm_port == NFS_PORT) &&
                    htons(fromsin->sin_port) >= IPPORT_RESERVED) {
                        syslog(LOG_WARNING,
                            "resvport set attempt by non-root");
                        goto done;
                }

                /*
                 * add to END of list
                 */
                pml = malloc(sizeof(struct pmaplist));
                if (pml == NULL) {
                        syslog(LOG_ERR, "out of memory");
                        svcerr_systemerr(xprt);
                        return;
                }

                pml->pml_map = reg;
                pml->pml_next = 0;
                if (pmaplist == NULL) {
                        pmaplist = pml;
                } else {
                        for (fnd = pmaplist; fnd->pml_next != 0;
                            fnd = fnd->pml_next)
                                ;
                        fnd->pml_next = pml;
                }
                ans = 1;
done:
                if ((!svc_sendreply(xprt, xdr_long, (caddr_t)&ans)) &&
                    debugging) {
                        (void)fprintf(stderr, "svc_sendreply\n");
                        abort();
                }
                break;
        case PMAPPROC_UNSET:
                /*
                 * Remove a program,version to port mapping.
                 */
                if (xprt != ltcpxprt && xprt != ludpxprt) {
                        syslog(LOG_WARNING,
                            "non-local unset attempt (might be from %s)",
                            inet_ntoa(fromsin->sin_addr));
                        svcerr_noproc(xprt);
                        return;
                }
                if (!svc_getargs(xprt, xdr_pmap, (caddr_t)&reg)) {
                        svcerr_decode(xprt);
                        break;
                }
                for (prevpml = NULL, pml = pmaplist; pml != NULL; ) {
                        if ((pml->pml_map.pm_prog != reg.pm_prog) ||
                            (pml->pml_map.pm_vers != reg.pm_vers)) {
                                /* both pml & prevpml move forwards */
                                prevpml = pml;
                                pml = pml->pml_next;
                                continue;
                        }
                        if ((pml->pml_map.pm_port < IPPORT_RESERVED ||
                            pml->pml_map.pm_port == NFS_PORT) &&
                            htons(fromsin->sin_port) >= IPPORT_RESERVED) {
                                syslog(LOG_WARNING,
                                    "resvport unset attempt by non-root");
                                break;
                        }

                        /* found it; pml moves forward, prevpml stays */
                        ans = 1;
                        t = pml;
                        pml = pml->pml_next;
                        if (prevpml == NULL)
                                pmaplist = pml;
                        else
                                prevpml->pml_next = pml;
                        free(t);
                }
                if ((!svc_sendreply(xprt, xdr_long, (caddr_t)&ans)) &&
                    debugging) {
                        fprintf(stderr, "svc_sendreply\n");
                        abort();
                }
                break;
        case PMAPPROC_GETPORT:
                /*
                 * Lookup the mapping for a program,version and return its port
                 */
                if (!svc_getargs(xprt, xdr_pmap, (caddr_t)&reg)) {
                        svcerr_decode(xprt);
                        break;
                }
                fnd = find_service(reg.pm_prog, reg.pm_vers, reg.pm_prot);
                if (fnd)
                        port = fnd->pml_map.pm_port;
                else
                        port = 0;
                if ((!svc_sendreply(xprt, xdr_long, (caddr_t)&port)) &&
                    debugging) {
                        fprintf(stderr, "svc_sendreply\n");
                        abort();
                }
                break;
        case PMAPPROC_DUMP:
                /*
                 * Return the current set of mapped program,version
                 */
                if (!svc_getargs(xprt, xdr_void, NULL)) {
                        svcerr_decode(xprt);
                        break;
                }
                if (!svc_sendreply(xprt, xdr_pmaplist, (caddr_t)&pmaplist) &&
                    debugging) {
                        fprintf(stderr, "svc_sendreply\n");
                        abort();
                }
                break;
        case PMAPPROC_CALLIT:
                /*
                 * Calls a procedure on the local machine.  If the requested
                 * procedure is not registered this procedure does not return
                 * error information!!
                 * This procedure is only supported on rpc/udp and calls via
                 * rpc/udp.  It passes null authentication parameters.
                 */
                callit(rqstp, xprt);
                break;
        default:
                svcerr_noproc(xprt);
                break;
        }
}


/*
 * Stuff for the rmtcall service
 */
#define ARGSIZE 9000

struct encap_parms {
        u_int arglen;
        char *args;
};

static bool_t
xdr_encap_parms(XDR *xdrs, struct encap_parms *epp)
{

        return (xdr_bytes(xdrs, &(epp->args), &(epp->arglen), ARGSIZE));
}

struct rmtcallargs {
        u_long  rmt_prog;
        u_long  rmt_vers;
        u_long  rmt_port;
        u_long  rmt_proc;
        struct encap_parms rmt_args;
};

/*
 * Version of xdr_rmtcall_args() that supports both directions
 */
static bool_t
portmap_xdr_rmtcall_args(XDR *xdrs, struct rmtcallargs *cap)
{

        /* does not get a port number */
        if (xdr_u_long(xdrs, &(cap->rmt_prog)) &&
            xdr_u_long(xdrs, &(cap->rmt_vers)) &&
            xdr_u_long(xdrs, &(cap->rmt_proc))) {
                return (xdr_encap_parms(xdrs, &(cap->rmt_args)));
        }
        return (FALSE);
}

/*
 * Version of xdr_rmtcallres() that supports both directions
 */
static bool_t
portmap_xdr_rmtcallres(XDR *xdrs, struct rmtcallargs *cap)
{
        if (xdr_u_long(xdrs, &(cap->rmt_port)))
                return (xdr_encap_parms(xdrs, &(cap->rmt_args)));
        return (FALSE);
}

/*
 * only worries about the struct encap_parms part of struct rmtcallargs.
 * The arglen must already be set!!
 */
static bool_t
xdr_opaque_parms(XDR *xdrs, struct rmtcallargs *cap)
{

        return (xdr_opaque(xdrs, cap->rmt_args.args, cap->rmt_args.arglen));
}

/*
 * This routine finds and sets the length of incoming opaque paraters
 * and then calls xdr_opaque_parms.
 */
static bool_t
xdr_len_opaque_parms(XDR *xdrs, struct rmtcallargs *cap)
{
        u_int beginpos, lowpos, highpos, currpos, pos;

        beginpos = lowpos = pos = xdr_getpos(xdrs);
        highpos = lowpos + ARGSIZE;
        while (highpos >= lowpos) {
                currpos = (lowpos + highpos) / 2;
                if (xdr_setpos(xdrs, currpos)) {
                        pos = currpos;
                        lowpos = currpos + 1;
                } else {
                        highpos = currpos - 1;
                }
        }
        xdr_setpos(xdrs, beginpos);
        cap->rmt_args.arglen = pos - beginpos;
        return (xdr_opaque_parms(xdrs, cap));
}

/*
 * Call a remote procedure service
 * This procedure is very quiet when things go wrong.
 * The proc is written to support broadcast rpc.  In the broadcast case,
 * a machine should shut-up instead of complain, less the requestor be
 * overrun with complaints at the expense of not hearing a valid reply ...
 *
 * This now forks so that the program & process that it calls can call
 * back to the portmapper.
 */
void
callit(struct svc_req *rqstp, SVCXPRT *xprt)
{
        struct rmtcallargs a;
        struct pmaplist *pml;
        u_short port;
        struct sockaddr_in me;
        pid_t pid;
        int so = -1;
        CLIENT *client;
        struct authunix_parms *au = (struct authunix_parms *)rqstp->rq_clntcred;
        struct timeval timeout;
        char buf[ARGSIZE];

        timeout.tv_sec = 5;
        timeout.tv_usec = 0;
        a.rmt_args.args = buf;
        if (!svc_getargs(xprt, portmap_xdr_rmtcall_args, (caddr_t)&a))
                return;
        if (!check_callit(svc_getcaller(xprt), a.rmt_prog, a.rmt_proc))
                return;
        if ((pml = find_service(a.rmt_prog, a.rmt_vers,
            (u_long)IPPROTO_UDP)) == NULL)
                return;

        /*
         * fork a child to do the work.  Parent immediately returns.
         * Child exits upon completion.
         */
        if ((pid = fork()) != 0) {
                if (pid == -1)
                        syslog(LOG_ERR, "CALLIT (prog %lu): fork: %m",
                            a.rmt_prog);
                return;
        }

        if (pledge("stdio inet", NULL) == -1)
                err(1, "pledge");

        port = pml->pml_map.pm_port;
        get_myaddress(&me);
        me.sin_port = htons(port);

        /* Avoid implicit binding to reserved port by clntudp_create() */
        so = socket(AF_INET, SOCK_DGRAM | SOCK_NONBLOCK, IPPROTO_UDP);
        if (so == -1)
                exit(1);

        client = clntudp_create(&me, a.rmt_prog, a.rmt_vers, timeout, &so);
        if (client != NULL) {
                if (rqstp->rq_cred.oa_flavor == AUTH_UNIX)
                        client->cl_auth = authunix_create(au->aup_machname,
                            au->aup_uid, au->aup_gid, au->aup_len, au->aup_gids);
                a.rmt_port = (u_long)port;
                if (clnt_call(client, a.rmt_proc, xdr_opaque_parms, &a,
                    xdr_len_opaque_parms, &a, timeout) == RPC_SUCCESS)
                        svc_sendreply(xprt, portmap_xdr_rmtcallres, (caddr_t)&a);
                AUTH_DESTROY(client->cl_auth);
                clnt_destroy(client);
        }
        (void)close(so);
        exit(0);
}

void
reap(int signo)
{
        int save_errno = errno;

        while (wait3(NULL, WNOHANG, NULL) > 0)
                ;
        errno = save_errno;
}

#define NFSPROG                 ((u_long) 100003)
#define MOUNTPROG               ((u_long) 100005)
#define YPXPROG                 ((u_long) 100069)
#define YPPROG                  ((u_long) 100004)
#define YPPROC_DOMAIN_NONACK    ((u_long) 2)
#define MOUNTPROC_MNT           ((u_long) 1)
#define XXXPROC_NOP             ((u_long) 0)

int
check_callit(struct sockaddr_in *addr, u_long prog, u_long aproc)
{
        if ((prog == PMAPPROG && aproc != XXXPROC_NOP) ||
            (prog == NFSPROG && aproc != XXXPROC_NOP) ||
            (prog == YPXPROG && aproc != XXXPROC_NOP) ||
            (prog == MOUNTPROG && aproc == MOUNTPROC_MNT) ||
            (prog == YPPROG && aproc != YPPROC_DOMAIN_NONACK)) {
                syslog(LOG_WARNING,
                    "callit prog %ld aproc %ld (might be from %s)",
                    prog, aproc, inet_ntoa(addr->sin_addr));
                return (FALSE);
        }
        return (TRUE);
}