xref: /openbsd-src/usr.sbin/portmap/portmap.c (revision 43003dfe3ad45d1698bed8a37f2b0f5b14f20d4f)
1 /*	$OpenBSD: portmap.c,v 1.37 2009/05/20 20:37:43 thib Exp $	*/
2 
3 /*-
4  * Copyright (c) 1996, 1997 Theo de Raadt (OpenBSD). All rights reserved.
5  * Copyright (c) 1990 The Regents of the University of California.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 char copyright[] =
35 "@(#) Copyright (c) 1990 The Regents of the University of California.\n\
36  All rights reserved.\n";
37 #endif /* not lint */
38 
39 #ifndef lint
40 #if 0
41 static char sccsid[] = "from: @(#)portmap.c	5.4 (Berkeley) 4/19/91";
42 #else
43 static char rcsid[] = "$OpenBSD: portmap.c,v 1.37 2009/05/20 20:37:43 thib Exp $";
44 #endif
45 #endif /* not lint */
46 
47 /*
48 @(#)portmap.c	2.3 88/08/11 4.0 RPCSRC
49 static char sccsid[] = "@(#)portmap.c 1.32 87/08/06 Copyr 1984 Sun Micro";
50 */
51 
52 /*
53  * portmap.c, Implements the program,version to port number mapping for
54  * rpc.
55  */
56 
57 /*
58  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
59  * unrestricted use provided that this legend is included on all tape
60  * media and as a part of the software program in whole or part.  Users
61  * may copy or modify Sun RPC without charge, but are not authorized
62  * to license or distribute it to anyone else except as part of a product or
63  * program developed by the user.
64  *
65  * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
66  * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
67  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
68  *
69  * Sun RPC is provided with no support and without any obligation on the
70  * part of Sun Microsystems, Inc. to assist in its use, correction,
71  * modification or enhancement.
72  *
73  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
74  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
75  * OR ANY PART THEREOF.
76  *
77  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
78  * or profits or other special, indirect and consequential damages, even if
79  * Sun has been advised of the possibility of such damages.
80  *
81  * Sun Microsystems, Inc.
82  * 2550 Garcia Avenue
83  * Mountain View, California  94043
84  */
85 
86 #include <sys/types.h>
87 #include <sys/socket.h>
88 #include <sys/ioctl.h>
89 #include <sys/wait.h>
90 #include <sys/resource.h>
91 
92 #include <rpcsvc/nfs_prot.h>
93 #include <arpa/inet.h>
94 #include <rpc/rpc.h>
95 #include <rpc/pmap_prot.h>
96 
97 #include <signal.h>
98 #include <stdio.h>
99 #include <stdlib.h>
100 #include <string.h>
101 #include <syslog.h>
102 #include <unistd.h>
103 #include <netdb.h>
104 #include <pwd.h>
105 #include <errno.h>
106 
107 void reg_service(struct svc_req *, SVCXPRT *);
108 void reap(int);
109 void callit(struct svc_req *, SVCXPRT *);
110 int check_callit(struct sockaddr_in *, u_long, u_long);
111 struct pmaplist *find_service(u_long, u_long, u_long);
112 
113 struct pmaplist *pmaplist;
114 int debugging = 0;
115 
116 SVCXPRT *ludpxprt, *ltcpxprt;
117 
118 int
119 main(int argc, char *argv[])
120 {
121 	int sock, lsock, c, on = 1, len = sizeof(struct sockaddr_in);
122 	struct sockaddr_in addr, laddr;
123 	struct pmaplist *pml;
124 	struct passwd *pw;
125 	SVCXPRT *xprt;
126 
127 	while ((c = getopt(argc, argv, "d")) != -1) {
128 		switch (c) {
129 
130 		case 'd':
131 			debugging = 1;
132 			break;
133 
134 		default:
135 			(void) fprintf(stderr, "usage: %s [-d]\n", argv[0]);
136 			exit(1);
137 		}
138 	}
139 
140 	if (!debugging && daemon(0, 0)) {
141 		(void) fprintf(stderr, "portmap: fork: %s", strerror(errno));
142 		exit(1);
143 	}
144 
145 	openlog("portmap", LOG_NDELAY | (debugging ? LOG_PID | LOG_PERROR : LOG_PID),
146 	    LOG_DAEMON);
147 
148 	bzero((char *)&addr, sizeof addr);
149 	addr.sin_addr.s_addr = 0;
150 	addr.sin_family = AF_INET;
151 	addr.sin_addr.s_addr = htonl(INADDR_ANY);
152 	addr.sin_port = htons(PMAPPORT);
153 
154 	bzero((char *)&laddr, sizeof laddr);
155 	laddr.sin_addr.s_addr = 0;
156 	laddr.sin_family = AF_INET;
157 	laddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
158 	laddr.sin_port = htons(PMAPPORT);
159 
160 	if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
161 		syslog(LOG_ERR, "cannot create udp socket: %m");
162 		exit(1);
163 	}
164 	setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
165 	if (bind(sock, (struct sockaddr *)&addr, len) != 0) {
166 		syslog(LOG_ERR, "cannot bind udp: %m");
167 		exit(1);
168 	}
169 
170 	if ((xprt = svcudp_create(sock)) == (SVCXPRT *)NULL) {
171 		syslog(LOG_ERR, "couldn't do udp_create");
172 		exit(1);
173 	}
174 
175 	if ((lsock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
176 		syslog(LOG_ERR, "cannot create udp socket: %m");
177 		exit(1);
178 	}
179 	setsockopt(lsock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
180 	if (bind(lsock, (struct sockaddr *)&laddr, len) != 0) {
181 		syslog(LOG_ERR, "cannot bind local udp: %m");
182 		exit(1);
183 	}
184 
185 	if ((ludpxprt = svcudp_create(lsock)) == (SVCXPRT *)NULL) {
186 		syslog(LOG_ERR, "couldn't do udp_create");
187 		exit(1);
188 	}
189 
190 	/* make an entry for ourself */
191 	pml = (struct pmaplist *)malloc((u_int)sizeof(struct pmaplist));
192 	if (pml == NULL) {
193 		syslog(LOG_ERR, "out of memory");
194 		exit(1);
195 	}
196 	pml->pml_next = 0;
197 	pml->pml_map.pm_prog = PMAPPROG;
198 	pml->pml_map.pm_vers = PMAPVERS;
199 	pml->pml_map.pm_prot = IPPROTO_UDP;
200 	pml->pml_map.pm_port = PMAPPORT;
201 	pmaplist = pml;
202 
203 	if ((sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
204 		syslog(LOG_ERR, "cannot create tcp socket: %m");
205 		exit(1);
206 	}
207 	setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
208 	if (bind(sock, (struct sockaddr *)&addr, len) != 0) {
209 		syslog(LOG_ERR, "cannot bind tcp: %m");
210 		exit(1);
211 	}
212 	if ((xprt = svctcp_create(sock, RPCSMALLMSGSIZE, RPCSMALLMSGSIZE))
213 	    == (SVCXPRT *)NULL) {
214 		syslog(LOG_ERR, "couldn't do tcp_create");
215 		exit(1);
216 	}
217 
218 	if ((lsock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
219 		syslog(LOG_ERR, "cannot create tcp socket: %m");
220 		exit(1);
221 	}
222 	setsockopt(lsock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on);
223 	if (bind(lsock, (struct sockaddr *)&laddr, len) != 0) {
224 		syslog(LOG_ERR, "cannot bind tcp: %m");
225 		exit(1);
226 	}
227 	if ((ltcpxprt = svctcp_create(lsock, RPCSMALLMSGSIZE,
228 	    RPCSMALLMSGSIZE)) == (SVCXPRT *)NULL) {
229 		syslog(LOG_ERR, "couldn't do tcp_create");
230 		exit(1);
231 	}
232 
233 	/* make an entry for ourself */
234 	pml = (struct pmaplist *)malloc((u_int)sizeof(struct pmaplist));
235 	if (pml == NULL) {
236 		syslog(LOG_ERR, "out of memory");
237 		exit(1);
238 	}
239 	pml->pml_map.pm_prog = PMAPPROG;
240 	pml->pml_map.pm_vers = PMAPVERS;
241 	pml->pml_map.pm_prot = IPPROTO_TCP;
242 	pml->pml_map.pm_port = PMAPPORT;
243 	pml->pml_next = pmaplist;
244 	pmaplist = pml;
245 
246 
247 	if ((pw = getpwnam("_portmap")) == NULL) {
248 		syslog(LOG_ERR, "no such user _portmap");
249 		exit(1);
250 	}
251 	if (chroot("/var/empty") == -1) {
252 		syslog(LOG_ERR, "cannot chdir to /var/empty.");
253 		exit(1);
254 	}
255 
256 	chdir("/");
257 	if (pw) {
258 		if (setgroups(1, &pw->pw_gid) == -1 ||
259 		    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1 ||
260 		    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1) {
261 			syslog(LOG_ERR, "revoke privs: %s", strerror(errno));
262 			exit(1);
263 		}
264 	}
265 	endpwent();
266 
267 	if (svc_register(xprt, PMAPPROG, PMAPVERS, reg_service, FALSE) == 0) {
268 		syslog(LOG_ERR, "svc_register failed.");
269 		exit(1);
270 	}
271 
272 	(void)signal(SIGCHLD, reap);
273 	svc_run();
274 	syslog(LOG_ERR, "svc_run returned unexpectedly");
275 	abort();
276 }
277 
278 #ifndef lint
279 /* need to override perror calls in rpc library */
280 void
281 perror(const char *what)
282 {
283 
284 	syslog(LOG_ERR, "%s: %m", what);
285 }
286 #endif
287 
288 struct pmaplist *
289 find_service(u_long prog, u_long vers, u_long prot)
290 {
291 	struct pmaplist *hit = NULL;
292 	struct pmaplist *pml;
293 
294 	for (pml = pmaplist; pml != NULL; pml = pml->pml_next) {
295 		if ((pml->pml_map.pm_prog != prog) ||
296 		    (pml->pml_map.pm_prot != prot))
297 			continue;
298 		hit = pml;
299 		if (pml->pml_map.pm_vers == vers)
300 			break;
301 	}
302 	return (hit);
303 }
304 
305 /*
306  * 1 OK, 0 not
307  */
308 void
309 reg_service(struct svc_req *rqstp, SVCXPRT *xprt)
310 {
311 	struct pmap reg;
312 	struct pmaplist *pml, *prevpml, *fnd;
313 	struct sockaddr_in *fromsin;
314 	long ans = 0, port;
315 	caddr_t t;
316 
317 	fromsin = svc_getcaller(xprt);
318 
319 	if (debugging)
320 		(void) fprintf(stderr, "server: about to do a switch\n");
321 	switch (rqstp->rq_proc) {
322 
323 	case PMAPPROC_NULL:
324 		/*
325 		 * Null proc call
326 		 */
327 		if (!svc_sendreply(xprt, xdr_void, (caddr_t)0) && debugging) {
328 			abort();
329 		}
330 		break;
331 
332 	case PMAPPROC_SET:
333 		/*
334 		 * Set a program,version to port mapping
335 		 */
336 		if (xprt != ltcpxprt && xprt != ludpxprt) {
337 			syslog(LOG_WARNING,
338 			    "non-local set attempt (might be from %s)",
339 			    inet_ntoa(fromsin->sin_addr));
340 			svcerr_noproc(xprt);
341 			return;
342 		}
343 		if (!svc_getargs(xprt, xdr_pmap, (caddr_t)&reg)) {
344 			svcerr_decode(xprt);
345 			break;
346 		}
347 
348 		/*
349 		 * check to see if already used
350 		 * find_service returns a hit even if
351 		 * the versions don't match, so check for it
352 		 */
353 		fnd = find_service(reg.pm_prog, reg.pm_vers, reg.pm_prot);
354 		if (fnd && fnd->pml_map.pm_vers == reg.pm_vers) {
355 			if (fnd->pml_map.pm_port == reg.pm_port)
356 				ans = 1;
357 			goto done;
358 		}
359 
360 		if (debugging)
361 			printf("set: prog %lu vers %lu port %lu\n",
362 			    reg.pm_prog, reg.pm_vers, reg.pm_port);
363 
364 		if (reg.pm_port & ~0xffff)
365 			goto done;
366 
367 		/*
368 		 * only permit localhost root to create
369 		 * mappings pointing at sensitive ports
370 		 */
371 		if ((reg.pm_port < IPPORT_RESERVED ||
372 		    reg.pm_port == NFS_PORT) &&
373 		    htons(fromsin->sin_port) >= IPPORT_RESERVED) {
374 			syslog(LOG_WARNING,
375 			    "resvport set attempt by non-root");
376 			goto done;
377 		}
378 
379 		/*
380 		 * add to END of list
381 		 */
382 		pml = (struct pmaplist *)malloc(sizeof(struct pmaplist));
383 		if (pml == NULL) {
384 			syslog(LOG_ERR, "out of memory");
385 			svcerr_systemerr(xprt);
386 			return;
387 		}
388 
389 		pml->pml_map = reg;
390 		pml->pml_next = 0;
391 		if (pmaplist == 0) {
392 			pmaplist = pml;
393 		} else {
394 			for (fnd = pmaplist; fnd->pml_next != 0;
395 			    fnd = fnd->pml_next);
396 			fnd->pml_next = pml;
397 		}
398 		ans = 1;
399 	done:
400 		if ((!svc_sendreply(xprt, xdr_long, (caddr_t)&ans)) &&
401 		    debugging) {
402 			(void) fprintf(stderr, "svc_sendreply\n");
403 			abort();
404 		}
405 		break;
406 
407 	case PMAPPROC_UNSET:
408 		/*
409 		 * Remove a program,version to port mapping.
410 		 */
411 		if (xprt != ltcpxprt && xprt != ludpxprt) {
412 			syslog(LOG_WARNING,
413 			    "non-local unset attempt (might be from %s)",
414 			    inet_ntoa(fromsin->sin_addr));
415 			svcerr_noproc(xprt);
416 			return;
417 		}
418 		if (!svc_getargs(xprt, xdr_pmap, (caddr_t)&reg)) {
419 			svcerr_decode(xprt);
420 			break;
421 		}
422 		for (prevpml = NULL, pml = pmaplist; pml != NULL; ) {
423 			if ((pml->pml_map.pm_prog != reg.pm_prog) ||
424 			    (pml->pml_map.pm_vers != reg.pm_vers)) {
425 				/* both pml & prevpml move forwards */
426 				prevpml = pml;
427 				pml = pml->pml_next;
428 				continue;
429 			}
430 			if ((pml->pml_map.pm_port < IPPORT_RESERVED ||
431 			    pml->pml_map.pm_port == NFS_PORT) &&
432 			    htons(fromsin->sin_port) >= IPPORT_RESERVED) {
433 				syslog(LOG_WARNING,
434 				    "resvport unset attempt by non-root");
435 				break;
436 			}
437 
438 			/* found it; pml moves forward, prevpml stays */
439 			ans = 1;
440 			t = (caddr_t)pml;
441 			pml = pml->pml_next;
442 			if (prevpml == NULL)
443 				pmaplist = pml;
444 			else
445 				prevpml->pml_next = pml;
446 			free(t);
447 		}
448 		if ((!svc_sendreply(xprt, xdr_long, (caddr_t)&ans)) &&
449 		    debugging) {
450 			fprintf(stderr, "svc_sendreply\n");
451 			abort();
452 		}
453 		break;
454 
455 	case PMAPPROC_GETPORT:
456 		/*
457 		 * Lookup the mapping for a program,version and return its port
458 		 */
459 		if (!svc_getargs(xprt, xdr_pmap, (caddr_t)&reg)) {
460 			svcerr_decode(xprt);
461 			break;
462 		}
463 		fnd = find_service(reg.pm_prog, reg.pm_vers, reg.pm_prot);
464 		if (fnd)
465 			port = fnd->pml_map.pm_port;
466 		else
467 			port = 0;
468 		if ((!svc_sendreply(xprt, xdr_long, (caddr_t)&port)) &&
469 		    debugging) {
470 			fprintf(stderr, "svc_sendreply\n");
471 			abort();
472 		}
473 		break;
474 
475 	case PMAPPROC_DUMP:
476 		/*
477 		 * Return the current set of mapped program,version
478 		 */
479 		if (!svc_getargs(xprt, xdr_void, NULL)) {
480 			svcerr_decode(xprt);
481 			break;
482 		}
483 		if (!svc_sendreply(xprt, xdr_pmaplist, (caddr_t)&pmaplist) &&
484 		    debugging) {
485 			fprintf(stderr, "svc_sendreply\n");
486 			abort();
487 		}
488 		break;
489 
490 	case PMAPPROC_CALLIT:
491 		/*
492 		 * Calls a procedure on the local machine.  If the requested
493 		 * procedure is not registered this procedure does not return
494 		 * error information!!
495 		 * This procedure is only supported on rpc/udp and calls via
496 		 * rpc/udp.  It passes null authentication parameters.
497 		 */
498 		callit(rqstp, xprt);
499 		break;
500 
501 	default:
502 		svcerr_noproc(xprt);
503 		break;
504 	}
505 }
506 
507 
508 /*
509  * Stuff for the rmtcall service
510  */
511 #define ARGSIZE 9000
512 
513 struct encap_parms {
514 	u_int arglen;
515 	char *args;
516 };
517 
518 static bool_t
519 xdr_encap_parms(XDR *xdrs, struct encap_parms *epp)
520 {
521 
522 	return (xdr_bytes(xdrs, &(epp->args), &(epp->arglen), ARGSIZE));
523 }
524 
525 struct rmtcallargs {
526 	u_long	rmt_prog;
527 	u_long	rmt_vers;
528 	u_long	rmt_port;
529 	u_long	rmt_proc;
530 	struct encap_parms rmt_args;
531 };
532 
533 static bool_t
534 xdr_rmtcall_args(XDR *xdrs, struct rmtcallargs *cap)
535 {
536 
537 	/* does not get a port number */
538 	if (xdr_u_long(xdrs, &(cap->rmt_prog)) &&
539 	    xdr_u_long(xdrs, &(cap->rmt_vers)) &&
540 	    xdr_u_long(xdrs, &(cap->rmt_proc))) {
541 		return (xdr_encap_parms(xdrs, &(cap->rmt_args)));
542 	}
543 	return (FALSE);
544 }
545 
546 static bool_t
547 xdr_rmtcall_result(XDR *xdrs, struct rmtcallargs *cap)
548 {
549 	if (xdr_u_long(xdrs, &(cap->rmt_port)))
550 		return (xdr_encap_parms(xdrs, &(cap->rmt_args)));
551 	return (FALSE);
552 }
553 
554 /*
555  * only worries about the struct encap_parms part of struct rmtcallargs.
556  * The arglen must already be set!!
557  */
558 static bool_t
559 xdr_opaque_parms(XDR *xdrs, struct rmtcallargs *cap)
560 {
561 
562 	return (xdr_opaque(xdrs, cap->rmt_args.args, cap->rmt_args.arglen));
563 }
564 
565 /*
566  * This routine finds and sets the length of incoming opaque paraters
567  * and then calls xdr_opaque_parms.
568  */
569 static bool_t
570 xdr_len_opaque_parms(XDR *xdrs, struct rmtcallargs *cap)
571 {
572 	u_int beginpos, lowpos, highpos, currpos, pos;
573 
574 	beginpos = lowpos = pos = xdr_getpos(xdrs);
575 	highpos = lowpos + ARGSIZE;
576 	while ((int)(highpos - lowpos) >= 0) {
577 		currpos = (lowpos + highpos) / 2;
578 		if (xdr_setpos(xdrs, currpos)) {
579 			pos = currpos;
580 			lowpos = currpos + 1;
581 		} else {
582 			highpos = currpos - 1;
583 		}
584 	}
585 	xdr_setpos(xdrs, beginpos);
586 	cap->rmt_args.arglen = pos - beginpos;
587 	return (xdr_opaque_parms(xdrs, cap));
588 }
589 
590 /*
591  * Call a remote procedure service
592  * This procedure is very quiet when things go wrong.
593  * The proc is written to support broadcast rpc.  In the broadcast case,
594  * a machine should shut-up instead of complain, less the requestor be
595  * overrun with complaints at the expense of not hearing a valid reply ...
596  *
597  * This now forks so that the program & process that it calls can call
598  * back to the portmapper.
599  */
600 void
601 callit(struct svc_req *rqstp, SVCXPRT *xprt)
602 {
603 	struct rmtcallargs a;
604 	struct pmaplist *pml;
605 	u_short port;
606 	struct sockaddr_in me;
607 	pid_t pid;
608 	int so = -1, dontblock = 1;
609 	CLIENT *client;
610 	struct authunix_parms *au = (struct authunix_parms *)rqstp->rq_clntcred;
611 	struct timeval timeout;
612 	char buf[ARGSIZE];
613 
614 	timeout.tv_sec = 5;
615 	timeout.tv_usec = 0;
616 	a.rmt_args.args = buf;
617 	if (!svc_getargs(xprt, xdr_rmtcall_args, (caddr_t)&a))
618 		return;
619 	if (!check_callit(svc_getcaller(xprt), a.rmt_prog, a.rmt_proc))
620 		return;
621 	if ((pml = find_service(a.rmt_prog, a.rmt_vers,
622 	    (u_long)IPPROTO_UDP)) == NULL)
623 		return;
624 
625 	/*
626 	 * fork a child to do the work.  Parent immediately returns.
627 	 * Child exits upon completion.
628 	 */
629 	if ((pid = fork()) != 0) {
630 		if (pid == -1)
631 			syslog(LOG_ERR, "CALLIT (prog %lu): fork: %m",
632 			    a.rmt_prog);
633 		return;
634 	}
635 	port = pml->pml_map.pm_port;
636 	get_myaddress(&me);
637 	me.sin_port = htons(port);
638 
639 	/* Avoid implicit binding to reserved port by clntudp_create() */
640 	so = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
641 	if (so == -1)
642 		exit(1);
643 	if (ioctl(so, FIONBIO, &dontblock) == -1)
644 		exit(1);
645 
646 	client = clntudp_create(&me, a.rmt_prog, a.rmt_vers, timeout, &so);
647 	if (client != (CLIENT *)NULL) {
648 		if (rqstp->rq_cred.oa_flavor == AUTH_UNIX)
649 			client->cl_auth = authunix_create(au->aup_machname,
650 			    au->aup_uid, au->aup_gid, au->aup_len, au->aup_gids);
651 		a.rmt_port = (u_long)port;
652 		if (clnt_call(client, a.rmt_proc, xdr_opaque_parms, &a,
653 		    xdr_len_opaque_parms, &a, timeout) == RPC_SUCCESS)
654 			svc_sendreply(xprt, xdr_rmtcall_result, (caddr_t)&a);
655 		AUTH_DESTROY(client->cl_auth);
656 		clnt_destroy(client);
657 	}
658 	(void)close(so);
659 	exit(0);
660 }
661 
662 /* ARGSUSED */
663 void
664 reap(int signo)
665 {
666 	int save_errno = errno;
667 
668 	while (wait3(NULL, WNOHANG, NULL) > 0)
669 		;
670 	errno = save_errno;
671 }
672 
673 #define	NFSPROG			((u_long) 100003)
674 #define	MOUNTPROG		((u_long) 100005)
675 #define	YPXPROG			((u_long) 100069)
676 #define	YPPROG			((u_long) 100004)
677 #define	YPPROC_DOMAIN_NONACK	((u_long) 2)
678 #define	MOUNTPROC_MNT		((u_long) 1)
679 #define XXXPROC_NOP		((u_long) 0)
680 
681 int
682 check_callit(struct sockaddr_in *addr, u_long prog, u_long aproc)
683 {
684 	if ((prog == PMAPPROG && aproc != XXXPROC_NOP) ||
685 	    (prog == NFSPROG && aproc != XXXPROC_NOP) ||
686 	    (prog == YPXPROG && aproc != XXXPROC_NOP) ||
687 	    (prog == MOUNTPROG && aproc == MOUNTPROC_MNT) ||
688 	    (prog == YPPROG && aproc != YPPROC_DOMAIN_NONACK)) {
689 		syslog(LOG_WARNING,
690 		    "callit prog %d aproc %d (might be from %s)",
691 		    (int)prog, (int)aproc, inet_ntoa(addr->sin_addr));
692 		return (FALSE);
693 	}
694 	return (TRUE);
695 }
696