xref: /freebsd/crypto/openssh/misc.c (revision 2e3f49888ec8851bafb22011533217487764fdb0)
1 /* $OpenBSD: misc.c,v 1.189 2023/10/12 03:36:32 djm Exp $ */
2 /*
3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
4  * Copyright (c) 2005-2020 Damien Miller.  All rights reserved.
5  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
6  *
7  * Permission to use, copy, modify, and distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 
21 #include "includes.h"
22 
23 #include <sys/types.h>
24 #include <sys/ioctl.h>
25 #include <sys/mman.h>
26 #include <sys/socket.h>
27 #include <sys/stat.h>
28 #include <sys/time.h>
29 #include <sys/wait.h>
30 #include <sys/un.h>
31 
32 #include <limits.h>
33 #ifdef HAVE_LIBGEN_H
34 # include <libgen.h>
35 #endif
36 #ifdef HAVE_POLL_H
37 #include <poll.h>
38 #endif
39 #ifdef HAVE_NLIST_H
40 #include <nlist.h>
41 #endif
42 #include <signal.h>
43 #include <stdarg.h>
44 #include <stdio.h>
45 #ifdef HAVE_STDINT_H
46 # include <stdint.h>
47 #endif
48 #include <stdlib.h>
49 #include <string.h>
50 #include <time.h>
51 #include <unistd.h>
52 
53 #include <netinet/in.h>
54 #include <netinet/in_systm.h>
55 #include <netinet/ip.h>
56 #include <netinet/tcp.h>
57 #include <arpa/inet.h>
58 
59 #include <ctype.h>
60 #include <errno.h>
61 #include <fcntl.h>
62 #include <netdb.h>
63 #ifdef HAVE_PATHS_H
64 # include <paths.h>
65 #include <pwd.h>
66 #include <grp.h>
67 #endif
68 #ifdef SSH_TUN_OPENBSD
69 #include <net/if.h>
70 #endif
71 
72 #include "xmalloc.h"
73 #include "misc.h"
74 #include "log.h"
75 #include "ssh.h"
76 #include "sshbuf.h"
77 #include "ssherr.h"
78 #include "platform.h"
79 
80 /* remove newline at end of string */
81 char *
82 chop(char *s)
83 {
84 	char *t = s;
85 	while (*t) {
86 		if (*t == '\n' || *t == '\r') {
87 			*t = '\0';
88 			return s;
89 		}
90 		t++;
91 	}
92 	return s;
93 
94 }
95 
96 /* remove whitespace from end of string */
97 void
98 rtrim(char *s)
99 {
100 	size_t i;
101 
102 	if ((i = strlen(s)) == 0)
103 		return;
104 	for (i--; i > 0; i--) {
105 		if (isspace((unsigned char)s[i]))
106 			s[i] = '\0';
107 	}
108 }
109 
110 /* set/unset filedescriptor to non-blocking */
111 int
112 set_nonblock(int fd)
113 {
114 	int val;
115 
116 	val = fcntl(fd, F_GETFL);
117 	if (val == -1) {
118 		error("fcntl(%d, F_GETFL): %s", fd, strerror(errno));
119 		return (-1);
120 	}
121 	if (val & O_NONBLOCK) {
122 		debug3("fd %d is O_NONBLOCK", fd);
123 		return (0);
124 	}
125 	debug2("fd %d setting O_NONBLOCK", fd);
126 	val |= O_NONBLOCK;
127 	if (fcntl(fd, F_SETFL, val) == -1) {
128 		debug("fcntl(%d, F_SETFL, O_NONBLOCK): %s", fd,
129 		    strerror(errno));
130 		return (-1);
131 	}
132 	return (0);
133 }
134 
135 int
136 unset_nonblock(int fd)
137 {
138 	int val;
139 
140 	val = fcntl(fd, F_GETFL);
141 	if (val == -1) {
142 		error("fcntl(%d, F_GETFL): %s", fd, strerror(errno));
143 		return (-1);
144 	}
145 	if (!(val & O_NONBLOCK)) {
146 		debug3("fd %d is not O_NONBLOCK", fd);
147 		return (0);
148 	}
149 	debug("fd %d clearing O_NONBLOCK", fd);
150 	val &= ~O_NONBLOCK;
151 	if (fcntl(fd, F_SETFL, val) == -1) {
152 		debug("fcntl(%d, F_SETFL, ~O_NONBLOCK): %s",
153 		    fd, strerror(errno));
154 		return (-1);
155 	}
156 	return (0);
157 }
158 
159 const char *
160 ssh_gai_strerror(int gaierr)
161 {
162 	if (gaierr == EAI_SYSTEM && errno != 0)
163 		return strerror(errno);
164 	return gai_strerror(gaierr);
165 }
166 
167 /* disable nagle on socket */
168 void
169 set_nodelay(int fd)
170 {
171 	int opt;
172 	socklen_t optlen;
173 
174 	optlen = sizeof opt;
175 	if (getsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, &optlen) == -1) {
176 		debug("getsockopt TCP_NODELAY: %.100s", strerror(errno));
177 		return;
178 	}
179 	if (opt == 1) {
180 		debug2("fd %d is TCP_NODELAY", fd);
181 		return;
182 	}
183 	opt = 1;
184 	debug2("fd %d setting TCP_NODELAY", fd);
185 	if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof opt) == -1)
186 		error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
187 }
188 
189 /* Allow local port reuse in TIME_WAIT */
190 int
191 set_reuseaddr(int fd)
192 {
193 	int on = 1;
194 
195 	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) {
196 		error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
197 		return -1;
198 	}
199 	return 0;
200 }
201 
202 /* Get/set routing domain */
203 char *
204 get_rdomain(int fd)
205 {
206 #if defined(HAVE_SYS_GET_RDOMAIN)
207 	return sys_get_rdomain(fd);
208 #elif defined(__OpenBSD__)
209 	int rtable;
210 	char *ret;
211 	socklen_t len = sizeof(rtable);
212 
213 	if (getsockopt(fd, SOL_SOCKET, SO_RTABLE, &rtable, &len) == -1) {
214 		error("Failed to get routing domain for fd %d: %s",
215 		    fd, strerror(errno));
216 		return NULL;
217 	}
218 	xasprintf(&ret, "%d", rtable);
219 	return ret;
220 #else /* defined(__OpenBSD__) */
221 	return NULL;
222 #endif
223 }
224 
225 int
226 set_rdomain(int fd, const char *name)
227 {
228 #if defined(HAVE_SYS_SET_RDOMAIN)
229 	return sys_set_rdomain(fd, name);
230 #elif defined(__OpenBSD__)
231 	int rtable;
232 	const char *errstr;
233 
234 	if (name == NULL)
235 		return 0; /* default table */
236 
237 	rtable = (int)strtonum(name, 0, 255, &errstr);
238 	if (errstr != NULL) {
239 		/* Shouldn't happen */
240 		error("Invalid routing domain \"%s\": %s", name, errstr);
241 		return -1;
242 	}
243 	if (setsockopt(fd, SOL_SOCKET, SO_RTABLE,
244 	    &rtable, sizeof(rtable)) == -1) {
245 		error("Failed to set routing domain %d on fd %d: %s",
246 		    rtable, fd, strerror(errno));
247 		return -1;
248 	}
249 	return 0;
250 #else /* defined(__OpenBSD__) */
251 	error("Setting routing domain is not supported on this platform");
252 	return -1;
253 #endif
254 }
255 
256 int
257 get_sock_af(int fd)
258 {
259 	struct sockaddr_storage to;
260 	socklen_t tolen = sizeof(to);
261 
262 	memset(&to, 0, sizeof(to));
263 	if (getsockname(fd, (struct sockaddr *)&to, &tolen) == -1)
264 		return -1;
265 #ifdef IPV4_IN_IPV6
266 	if (to.ss_family == AF_INET6 &&
267 	    IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
268 		return AF_INET;
269 #endif
270 	return to.ss_family;
271 }
272 
273 void
274 set_sock_tos(int fd, int tos)
275 {
276 #ifndef IP_TOS_IS_BROKEN
277 	int af;
278 
279 	switch ((af = get_sock_af(fd))) {
280 	case -1:
281 		/* assume not a socket */
282 		break;
283 	case AF_INET:
284 # ifdef IP_TOS
285 		debug3_f("set socket %d IP_TOS 0x%02x", fd, tos);
286 		if (setsockopt(fd, IPPROTO_IP, IP_TOS,
287 		    &tos, sizeof(tos)) == -1) {
288 			error("setsockopt socket %d IP_TOS %d: %s",
289 			    fd, tos, strerror(errno));
290 		}
291 # endif /* IP_TOS */
292 		break;
293 	case AF_INET6:
294 # ifdef IPV6_TCLASS
295 		debug3_f("set socket %d IPV6_TCLASS 0x%02x", fd, tos);
296 		if (setsockopt(fd, IPPROTO_IPV6, IPV6_TCLASS,
297 		    &tos, sizeof(tos)) == -1) {
298 			error("setsockopt socket %d IPV6_TCLASS %d: %s",
299 			    fd, tos, strerror(errno));
300 		}
301 # endif /* IPV6_TCLASS */
302 		break;
303 	default:
304 		debug2_f("unsupported socket family %d", af);
305 		break;
306 	}
307 #endif /* IP_TOS_IS_BROKEN */
308 }
309 
310 /*
311  * Wait up to *timeoutp milliseconds for events on fd. Updates
312  * *timeoutp with time remaining.
313  * Returns 0 if fd ready or -1 on timeout or error (see errno).
314  */
315 static int
316 waitfd(int fd, int *timeoutp, short events, volatile sig_atomic_t *stop)
317 {
318 	struct pollfd pfd;
319 	struct timespec timeout;
320 	int oerrno, r;
321 	sigset_t nsigset, osigset;
322 
323 	if (timeoutp && *timeoutp == -1)
324 		timeoutp = NULL;
325 	pfd.fd = fd;
326 	pfd.events = events;
327 	ptimeout_init(&timeout);
328 	if (timeoutp != NULL)
329 		ptimeout_deadline_ms(&timeout, *timeoutp);
330 	if (stop != NULL)
331 		sigfillset(&nsigset);
332 	for (; timeoutp == NULL || *timeoutp >= 0;) {
333 		if (stop != NULL) {
334 			sigprocmask(SIG_BLOCK, &nsigset, &osigset);
335 			if (*stop) {
336 				sigprocmask(SIG_SETMASK, &osigset, NULL);
337 				errno = EINTR;
338 				return -1;
339 			}
340 		}
341 		r = ppoll(&pfd, 1, ptimeout_get_tsp(&timeout),
342 		    stop != NULL ? &osigset : NULL);
343 		oerrno = errno;
344 		if (stop != NULL)
345 			sigprocmask(SIG_SETMASK, &osigset, NULL);
346 		if (timeoutp)
347 			*timeoutp = ptimeout_get_ms(&timeout);
348 		errno = oerrno;
349 		if (r > 0)
350 			return 0;
351 		else if (r == -1 && errno != EAGAIN && errno != EINTR)
352 			return -1;
353 		else if (r == 0)
354 			break;
355 	}
356 	/* timeout */
357 	errno = ETIMEDOUT;
358 	return -1;
359 }
360 
361 /*
362  * Wait up to *timeoutp milliseconds for fd to be readable. Updates
363  * *timeoutp with time remaining.
364  * Returns 0 if fd ready or -1 on timeout or error (see errno).
365  */
366 int
367 waitrfd(int fd, int *timeoutp, volatile sig_atomic_t *stop) {
368 	return waitfd(fd, timeoutp, POLLIN, stop);
369 }
370 
371 /*
372  * Attempt a non-blocking connect(2) to the specified address, waiting up to
373  * *timeoutp milliseconds for the connection to complete. If the timeout is
374  * <=0, then wait indefinitely.
375  *
376  * Returns 0 on success or -1 on failure.
377  */
378 int
379 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
380     socklen_t addrlen, int *timeoutp)
381 {
382 	int optval = 0;
383 	socklen_t optlen = sizeof(optval);
384 
385 	/* No timeout: just do a blocking connect() */
386 	if (timeoutp == NULL || *timeoutp <= 0)
387 		return connect(sockfd, serv_addr, addrlen);
388 
389 	set_nonblock(sockfd);
390 	for (;;) {
391 		if (connect(sockfd, serv_addr, addrlen) == 0) {
392 			/* Succeeded already? */
393 			unset_nonblock(sockfd);
394 			return 0;
395 		} else if (errno == EINTR)
396 			continue;
397 		else if (errno != EINPROGRESS)
398 			return -1;
399 		break;
400 	}
401 
402 	if (waitfd(sockfd, timeoutp, POLLIN | POLLOUT, NULL) == -1)
403 		return -1;
404 
405 	/* Completed or failed */
406 	if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
407 		debug("getsockopt: %s", strerror(errno));
408 		return -1;
409 	}
410 	if (optval != 0) {
411 		errno = optval;
412 		return -1;
413 	}
414 	unset_nonblock(sockfd);
415 	return 0;
416 }
417 
418 /* Characters considered whitespace in strsep calls. */
419 #define WHITESPACE " \t\r\n"
420 #define QUOTE	"\""
421 
422 /* return next token in configuration line */
423 static char *
424 strdelim_internal(char **s, int split_equals)
425 {
426 	char *old;
427 	int wspace = 0;
428 
429 	if (*s == NULL)
430 		return NULL;
431 
432 	old = *s;
433 
434 	*s = strpbrk(*s,
435 	    split_equals ? WHITESPACE QUOTE "=" : WHITESPACE QUOTE);
436 	if (*s == NULL)
437 		return (old);
438 
439 	if (*s[0] == '\"') {
440 		memmove(*s, *s + 1, strlen(*s)); /* move nul too */
441 		/* Find matching quote */
442 		if ((*s = strpbrk(*s, QUOTE)) == NULL) {
443 			return (NULL);		/* no matching quote */
444 		} else {
445 			*s[0] = '\0';
446 			*s += strspn(*s + 1, WHITESPACE) + 1;
447 			return (old);
448 		}
449 	}
450 
451 	/* Allow only one '=' to be skipped */
452 	if (split_equals && *s[0] == '=')
453 		wspace = 1;
454 	*s[0] = '\0';
455 
456 	/* Skip any extra whitespace after first token */
457 	*s += strspn(*s + 1, WHITESPACE) + 1;
458 	if (split_equals && *s[0] == '=' && !wspace)
459 		*s += strspn(*s + 1, WHITESPACE) + 1;
460 
461 	return (old);
462 }
463 
464 /*
465  * Return next token in configuration line; splts on whitespace or a
466  * single '=' character.
467  */
468 char *
469 strdelim(char **s)
470 {
471 	return strdelim_internal(s, 1);
472 }
473 
474 /*
475  * Return next token in configuration line; splts on whitespace only.
476  */
477 char *
478 strdelimw(char **s)
479 {
480 	return strdelim_internal(s, 0);
481 }
482 
483 struct passwd *
484 pwcopy(struct passwd *pw)
485 {
486 	struct passwd *copy = xcalloc(1, sizeof(*copy));
487 
488 	copy->pw_name = xstrdup(pw->pw_name);
489 	copy->pw_passwd = xstrdup(pw->pw_passwd == NULL ? "*" : pw->pw_passwd);
490 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
491 	copy->pw_gecos = xstrdup(pw->pw_gecos);
492 #endif
493 	copy->pw_uid = pw->pw_uid;
494 	copy->pw_gid = pw->pw_gid;
495 #ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
496 	copy->pw_expire = pw->pw_expire;
497 #endif
498 #ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
499 	copy->pw_change = pw->pw_change;
500 #endif
501 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
502 	copy->pw_class = xstrdup(pw->pw_class);
503 #endif
504 	copy->pw_dir = xstrdup(pw->pw_dir);
505 	copy->pw_shell = xstrdup(pw->pw_shell);
506 	return copy;
507 }
508 
509 /*
510  * Convert ASCII string to TCP/IP port number.
511  * Port must be >=0 and <=65535.
512  * Return -1 if invalid.
513  */
514 int
515 a2port(const char *s)
516 {
517 	struct servent *se;
518 	long long port;
519 	const char *errstr;
520 
521 	port = strtonum(s, 0, 65535, &errstr);
522 	if (errstr == NULL)
523 		return (int)port;
524 	if ((se = getservbyname(s, "tcp")) != NULL)
525 		return ntohs(se->s_port);
526 	return -1;
527 }
528 
529 int
530 a2tun(const char *s, int *remote)
531 {
532 	const char *errstr = NULL;
533 	char *sp, *ep;
534 	int tun;
535 
536 	if (remote != NULL) {
537 		*remote = SSH_TUNID_ANY;
538 		sp = xstrdup(s);
539 		if ((ep = strchr(sp, ':')) == NULL) {
540 			free(sp);
541 			return (a2tun(s, NULL));
542 		}
543 		ep[0] = '\0'; ep++;
544 		*remote = a2tun(ep, NULL);
545 		tun = a2tun(sp, NULL);
546 		free(sp);
547 		return (*remote == SSH_TUNID_ERR ? *remote : tun);
548 	}
549 
550 	if (strcasecmp(s, "any") == 0)
551 		return (SSH_TUNID_ANY);
552 
553 	tun = strtonum(s, 0, SSH_TUNID_MAX, &errstr);
554 	if (errstr != NULL)
555 		return (SSH_TUNID_ERR);
556 
557 	return (tun);
558 }
559 
560 #define SECONDS		1
561 #define MINUTES		(SECONDS * 60)
562 #define HOURS		(MINUTES * 60)
563 #define DAYS		(HOURS * 24)
564 #define WEEKS		(DAYS * 7)
565 
566 /*
567  * Convert a time string into seconds; format is
568  * a sequence of:
569  *      time[qualifier]
570  *
571  * Valid time qualifiers are:
572  *      <none>  seconds
573  *      s|S     seconds
574  *      m|M     minutes
575  *      h|H     hours
576  *      d|D     days
577  *      w|W     weeks
578  *
579  * Examples:
580  *      90m     90 minutes
581  *      1h30m   90 minutes
582  *      2d      2 days
583  *      1w      1 week
584  *
585  * Return -1 if time string is invalid.
586  */
587 int
588 convtime(const char *s)
589 {
590 	long total, secs, multiplier;
591 	const char *p;
592 	char *endp;
593 
594 	errno = 0;
595 	total = 0;
596 	p = s;
597 
598 	if (p == NULL || *p == '\0')
599 		return -1;
600 
601 	while (*p) {
602 		secs = strtol(p, &endp, 10);
603 		if (p == endp ||
604 		    (errno == ERANGE && (secs == INT_MIN || secs == INT_MAX)) ||
605 		    secs < 0)
606 			return -1;
607 
608 		multiplier = 1;
609 		switch (*endp++) {
610 		case '\0':
611 			endp--;
612 			break;
613 		case 's':
614 		case 'S':
615 			break;
616 		case 'm':
617 		case 'M':
618 			multiplier = MINUTES;
619 			break;
620 		case 'h':
621 		case 'H':
622 			multiplier = HOURS;
623 			break;
624 		case 'd':
625 		case 'D':
626 			multiplier = DAYS;
627 			break;
628 		case 'w':
629 		case 'W':
630 			multiplier = WEEKS;
631 			break;
632 		default:
633 			return -1;
634 		}
635 		if (secs > INT_MAX / multiplier)
636 			return -1;
637 		secs *= multiplier;
638 		if  (total > INT_MAX - secs)
639 			return -1;
640 		total += secs;
641 		if (total < 0)
642 			return -1;
643 		p = endp;
644 	}
645 
646 	return total;
647 }
648 
649 #define TF_BUFS	8
650 #define TF_LEN	9
651 
652 const char *
653 fmt_timeframe(time_t t)
654 {
655 	char		*buf;
656 	static char	 tfbuf[TF_BUFS][TF_LEN];	/* ring buffer */
657 	static int	 idx = 0;
658 	unsigned int	 sec, min, hrs, day;
659 	unsigned long long	week;
660 
661 	buf = tfbuf[idx++];
662 	if (idx == TF_BUFS)
663 		idx = 0;
664 
665 	week = t;
666 
667 	sec = week % 60;
668 	week /= 60;
669 	min = week % 60;
670 	week /= 60;
671 	hrs = week % 24;
672 	week /= 24;
673 	day = week % 7;
674 	week /= 7;
675 
676 	if (week > 0)
677 		snprintf(buf, TF_LEN, "%02lluw%01ud%02uh", week, day, hrs);
678 	else if (day > 0)
679 		snprintf(buf, TF_LEN, "%01ud%02uh%02um", day, hrs, min);
680 	else
681 		snprintf(buf, TF_LEN, "%02u:%02u:%02u", hrs, min, sec);
682 
683 	return (buf);
684 }
685 
686 /*
687  * Returns a standardized host+port identifier string.
688  * Caller must free returned string.
689  */
690 char *
691 put_host_port(const char *host, u_short port)
692 {
693 	char *hoststr;
694 
695 	if (port == 0 || port == SSH_DEFAULT_PORT)
696 		return(xstrdup(host));
697 	if (asprintf(&hoststr, "[%s]:%d", host, (int)port) == -1)
698 		fatal("put_host_port: asprintf: %s", strerror(errno));
699 	debug3("put_host_port: %s", hoststr);
700 	return hoststr;
701 }
702 
703 /*
704  * Search for next delimiter between hostnames/addresses and ports.
705  * Argument may be modified (for termination).
706  * Returns *cp if parsing succeeds.
707  * *cp is set to the start of the next field, if one was found.
708  * The delimiter char, if present, is stored in delim.
709  * If this is the last field, *cp is set to NULL.
710  */
711 char *
712 hpdelim2(char **cp, char *delim)
713 {
714 	char *s, *old;
715 
716 	if (cp == NULL || *cp == NULL)
717 		return NULL;
718 
719 	old = s = *cp;
720 	if (*s == '[') {
721 		if ((s = strchr(s, ']')) == NULL)
722 			return NULL;
723 		else
724 			s++;
725 	} else if ((s = strpbrk(s, ":/")) == NULL)
726 		s = *cp + strlen(*cp); /* skip to end (see first case below) */
727 
728 	switch (*s) {
729 	case '\0':
730 		*cp = NULL;	/* no more fields*/
731 		break;
732 
733 	case ':':
734 	case '/':
735 		if (delim != NULL)
736 			*delim = *s;
737 		*s = '\0';	/* terminate */
738 		*cp = s + 1;
739 		break;
740 
741 	default:
742 		return NULL;
743 	}
744 
745 	return old;
746 }
747 
748 /* The common case: only accept colon as delimiter. */
749 char *
750 hpdelim(char **cp)
751 {
752 	char *r, delim = '\0';
753 
754 	r =  hpdelim2(cp, &delim);
755 	if (delim == '/')
756 		return NULL;
757 	return r;
758 }
759 
760 char *
761 cleanhostname(char *host)
762 {
763 	if (*host == '[' && host[strlen(host) - 1] == ']') {
764 		host[strlen(host) - 1] = '\0';
765 		return (host + 1);
766 	} else
767 		return host;
768 }
769 
770 char *
771 colon(char *cp)
772 {
773 	int flag = 0;
774 
775 	if (*cp == ':')		/* Leading colon is part of file name. */
776 		return NULL;
777 	if (*cp == '[')
778 		flag = 1;
779 
780 	for (; *cp; ++cp) {
781 		if (*cp == '@' && *(cp+1) == '[')
782 			flag = 1;
783 		if (*cp == ']' && *(cp+1) == ':' && flag)
784 			return (cp+1);
785 		if (*cp == ':' && !flag)
786 			return (cp);
787 		if (*cp == '/')
788 			return NULL;
789 	}
790 	return NULL;
791 }
792 
793 /*
794  * Parse a [user@]host:[path] string.
795  * Caller must free returned user, host and path.
796  * Any of the pointer return arguments may be NULL (useful for syntax checking).
797  * If user was not specified then *userp will be set to NULL.
798  * If host was not specified then *hostp will be set to NULL.
799  * If path was not specified then *pathp will be set to ".".
800  * Returns 0 on success, -1 on failure.
801  */
802 int
803 parse_user_host_path(const char *s, char **userp, char **hostp, char **pathp)
804 {
805 	char *user = NULL, *host = NULL, *path = NULL;
806 	char *sdup, *tmp;
807 	int ret = -1;
808 
809 	if (userp != NULL)
810 		*userp = NULL;
811 	if (hostp != NULL)
812 		*hostp = NULL;
813 	if (pathp != NULL)
814 		*pathp = NULL;
815 
816 	sdup = xstrdup(s);
817 
818 	/* Check for remote syntax: [user@]host:[path] */
819 	if ((tmp = colon(sdup)) == NULL)
820 		goto out;
821 
822 	/* Extract optional path */
823 	*tmp++ = '\0';
824 	if (*tmp == '\0')
825 		tmp = ".";
826 	path = xstrdup(tmp);
827 
828 	/* Extract optional user and mandatory host */
829 	tmp = strrchr(sdup, '@');
830 	if (tmp != NULL) {
831 		*tmp++ = '\0';
832 		host = xstrdup(cleanhostname(tmp));
833 		if (*sdup != '\0')
834 			user = xstrdup(sdup);
835 	} else {
836 		host = xstrdup(cleanhostname(sdup));
837 		user = NULL;
838 	}
839 
840 	/* Success */
841 	if (userp != NULL) {
842 		*userp = user;
843 		user = NULL;
844 	}
845 	if (hostp != NULL) {
846 		*hostp = host;
847 		host = NULL;
848 	}
849 	if (pathp != NULL) {
850 		*pathp = path;
851 		path = NULL;
852 	}
853 	ret = 0;
854 out:
855 	free(sdup);
856 	free(user);
857 	free(host);
858 	free(path);
859 	return ret;
860 }
861 
862 /*
863  * Parse a [user@]host[:port] string.
864  * Caller must free returned user and host.
865  * Any of the pointer return arguments may be NULL (useful for syntax checking).
866  * If user was not specified then *userp will be set to NULL.
867  * If port was not specified then *portp will be -1.
868  * Returns 0 on success, -1 on failure.
869  */
870 int
871 parse_user_host_port(const char *s, char **userp, char **hostp, int *portp)
872 {
873 	char *sdup, *cp, *tmp;
874 	char *user = NULL, *host = NULL;
875 	int port = -1, ret = -1;
876 
877 	if (userp != NULL)
878 		*userp = NULL;
879 	if (hostp != NULL)
880 		*hostp = NULL;
881 	if (portp != NULL)
882 		*portp = -1;
883 
884 	if ((sdup = tmp = strdup(s)) == NULL)
885 		return -1;
886 	/* Extract optional username */
887 	if ((cp = strrchr(tmp, '@')) != NULL) {
888 		*cp = '\0';
889 		if (*tmp == '\0')
890 			goto out;
891 		if ((user = strdup(tmp)) == NULL)
892 			goto out;
893 		tmp = cp + 1;
894 	}
895 	/* Extract mandatory hostname */
896 	if ((cp = hpdelim(&tmp)) == NULL || *cp == '\0')
897 		goto out;
898 	host = xstrdup(cleanhostname(cp));
899 	/* Convert and verify optional port */
900 	if (tmp != NULL && *tmp != '\0') {
901 		if ((port = a2port(tmp)) <= 0)
902 			goto out;
903 	}
904 	/* Success */
905 	if (userp != NULL) {
906 		*userp = user;
907 		user = NULL;
908 	}
909 	if (hostp != NULL) {
910 		*hostp = host;
911 		host = NULL;
912 	}
913 	if (portp != NULL)
914 		*portp = port;
915 	ret = 0;
916  out:
917 	free(sdup);
918 	free(user);
919 	free(host);
920 	return ret;
921 }
922 
923 /*
924  * Converts a two-byte hex string to decimal.
925  * Returns the decimal value or -1 for invalid input.
926  */
927 static int
928 hexchar(const char *s)
929 {
930 	unsigned char result[2];
931 	int i;
932 
933 	for (i = 0; i < 2; i++) {
934 		if (s[i] >= '0' && s[i] <= '9')
935 			result[i] = (unsigned char)(s[i] - '0');
936 		else if (s[i] >= 'a' && s[i] <= 'f')
937 			result[i] = (unsigned char)(s[i] - 'a') + 10;
938 		else if (s[i] >= 'A' && s[i] <= 'F')
939 			result[i] = (unsigned char)(s[i] - 'A') + 10;
940 		else
941 			return -1;
942 	}
943 	return (result[0] << 4) | result[1];
944 }
945 
946 /*
947  * Decode an url-encoded string.
948  * Returns a newly allocated string on success or NULL on failure.
949  */
950 static char *
951 urldecode(const char *src)
952 {
953 	char *ret, *dst;
954 	int ch;
955 	size_t srclen;
956 
957 	if ((srclen = strlen(src)) >= SIZE_MAX)
958 		fatal_f("input too large");
959 	ret = xmalloc(srclen + 1);
960 	for (dst = ret; *src != '\0'; src++) {
961 		switch (*src) {
962 		case '+':
963 			*dst++ = ' ';
964 			break;
965 		case '%':
966 			if (!isxdigit((unsigned char)src[1]) ||
967 			    !isxdigit((unsigned char)src[2]) ||
968 			    (ch = hexchar(src + 1)) == -1) {
969 				free(ret);
970 				return NULL;
971 			}
972 			*dst++ = ch;
973 			src += 2;
974 			break;
975 		default:
976 			*dst++ = *src;
977 			break;
978 		}
979 	}
980 	*dst = '\0';
981 
982 	return ret;
983 }
984 
985 /*
986  * Parse an (scp|ssh|sftp)://[user@]host[:port][/path] URI.
987  * See https://tools.ietf.org/html/draft-ietf-secsh-scp-sftp-ssh-uri-04
988  * Either user or path may be url-encoded (but not host or port).
989  * Caller must free returned user, host and path.
990  * Any of the pointer return arguments may be NULL (useful for syntax checking)
991  * but the scheme must always be specified.
992  * If user was not specified then *userp will be set to NULL.
993  * If port was not specified then *portp will be -1.
994  * If path was not specified then *pathp will be set to NULL.
995  * Returns 0 on success, 1 if non-uri/wrong scheme, -1 on error/invalid uri.
996  */
997 int
998 parse_uri(const char *scheme, const char *uri, char **userp, char **hostp,
999     int *portp, char **pathp)
1000 {
1001 	char *uridup, *cp, *tmp, ch;
1002 	char *user = NULL, *host = NULL, *path = NULL;
1003 	int port = -1, ret = -1;
1004 	size_t len;
1005 
1006 	len = strlen(scheme);
1007 	if (strncmp(uri, scheme, len) != 0 || strncmp(uri + len, "://", 3) != 0)
1008 		return 1;
1009 	uri += len + 3;
1010 
1011 	if (userp != NULL)
1012 		*userp = NULL;
1013 	if (hostp != NULL)
1014 		*hostp = NULL;
1015 	if (portp != NULL)
1016 		*portp = -1;
1017 	if (pathp != NULL)
1018 		*pathp = NULL;
1019 
1020 	uridup = tmp = xstrdup(uri);
1021 
1022 	/* Extract optional ssh-info (username + connection params) */
1023 	if ((cp = strchr(tmp, '@')) != NULL) {
1024 		char *delim;
1025 
1026 		*cp = '\0';
1027 		/* Extract username and connection params */
1028 		if ((delim = strchr(tmp, ';')) != NULL) {
1029 			/* Just ignore connection params for now */
1030 			*delim = '\0';
1031 		}
1032 		if (*tmp == '\0') {
1033 			/* Empty username */
1034 			goto out;
1035 		}
1036 		if ((user = urldecode(tmp)) == NULL)
1037 			goto out;
1038 		tmp = cp + 1;
1039 	}
1040 
1041 	/* Extract mandatory hostname */
1042 	if ((cp = hpdelim2(&tmp, &ch)) == NULL || *cp == '\0')
1043 		goto out;
1044 	host = xstrdup(cleanhostname(cp));
1045 	if (!valid_domain(host, 0, NULL))
1046 		goto out;
1047 
1048 	if (tmp != NULL && *tmp != '\0') {
1049 		if (ch == ':') {
1050 			/* Convert and verify port. */
1051 			if ((cp = strchr(tmp, '/')) != NULL)
1052 				*cp = '\0';
1053 			if ((port = a2port(tmp)) <= 0)
1054 				goto out;
1055 			tmp = cp ? cp + 1 : NULL;
1056 		}
1057 		if (tmp != NULL && *tmp != '\0') {
1058 			/* Extract optional path */
1059 			if ((path = urldecode(tmp)) == NULL)
1060 				goto out;
1061 		}
1062 	}
1063 
1064 	/* Success */
1065 	if (userp != NULL) {
1066 		*userp = user;
1067 		user = NULL;
1068 	}
1069 	if (hostp != NULL) {
1070 		*hostp = host;
1071 		host = NULL;
1072 	}
1073 	if (portp != NULL)
1074 		*portp = port;
1075 	if (pathp != NULL) {
1076 		*pathp = path;
1077 		path = NULL;
1078 	}
1079 	ret = 0;
1080  out:
1081 	free(uridup);
1082 	free(user);
1083 	free(host);
1084 	free(path);
1085 	return ret;
1086 }
1087 
1088 /* function to assist building execv() arguments */
1089 void
1090 addargs(arglist *args, char *fmt, ...)
1091 {
1092 	va_list ap;
1093 	char *cp;
1094 	u_int nalloc;
1095 	int r;
1096 
1097 	va_start(ap, fmt);
1098 	r = vasprintf(&cp, fmt, ap);
1099 	va_end(ap);
1100 	if (r == -1)
1101 		fatal_f("argument too long");
1102 
1103 	nalloc = args->nalloc;
1104 	if (args->list == NULL) {
1105 		nalloc = 32;
1106 		args->num = 0;
1107 	} else if (args->num > (256 * 1024))
1108 		fatal_f("too many arguments");
1109 	else if (args->num >= args->nalloc)
1110 		fatal_f("arglist corrupt");
1111 	else if (args->num+2 >= nalloc)
1112 		nalloc *= 2;
1113 
1114 	args->list = xrecallocarray(args->list, args->nalloc,
1115 	    nalloc, sizeof(char *));
1116 	args->nalloc = nalloc;
1117 	args->list[args->num++] = cp;
1118 	args->list[args->num] = NULL;
1119 }
1120 
1121 void
1122 replacearg(arglist *args, u_int which, char *fmt, ...)
1123 {
1124 	va_list ap;
1125 	char *cp;
1126 	int r;
1127 
1128 	va_start(ap, fmt);
1129 	r = vasprintf(&cp, fmt, ap);
1130 	va_end(ap);
1131 	if (r == -1)
1132 		fatal_f("argument too long");
1133 	if (args->list == NULL || args->num >= args->nalloc)
1134 		fatal_f("arglist corrupt");
1135 
1136 	if (which >= args->num)
1137 		fatal_f("tried to replace invalid arg %d >= %d",
1138 		    which, args->num);
1139 	free(args->list[which]);
1140 	args->list[which] = cp;
1141 }
1142 
1143 void
1144 freeargs(arglist *args)
1145 {
1146 	u_int i;
1147 
1148 	if (args == NULL)
1149 		return;
1150 	if (args->list != NULL && args->num < args->nalloc) {
1151 		for (i = 0; i < args->num; i++)
1152 			free(args->list[i]);
1153 		free(args->list);
1154 	}
1155 	args->nalloc = args->num = 0;
1156 	args->list = NULL;
1157 }
1158 
1159 /*
1160  * Expands tildes in the file name.  Returns data allocated by xmalloc.
1161  * Warning: this calls getpw*.
1162  */
1163 int
1164 tilde_expand(const char *filename, uid_t uid, char **retp)
1165 {
1166 	char *ocopy = NULL, *copy, *s = NULL;
1167 	const char *path = NULL, *user = NULL;
1168 	struct passwd *pw;
1169 	size_t len;
1170 	int ret = -1, r, slash;
1171 
1172 	*retp = NULL;
1173 	if (*filename != '~') {
1174 		*retp = xstrdup(filename);
1175 		return 0;
1176 	}
1177 	ocopy = copy = xstrdup(filename + 1);
1178 
1179 	if (*copy == '\0')				/* ~ */
1180 		path = NULL;
1181 	else if (*copy == '/') {
1182 		copy += strspn(copy, "/");
1183 		if (*copy == '\0')
1184 			path = NULL;			/* ~/ */
1185 		else
1186 			path = copy;			/* ~/path */
1187 	} else {
1188 		user = copy;
1189 		if ((path = strchr(copy, '/')) != NULL) {
1190 			copy[path - copy] = '\0';
1191 			path++;
1192 			path += strspn(path, "/");
1193 			if (*path == '\0')		/* ~user/ */
1194 				path = NULL;
1195 			/* else				 ~user/path */
1196 		}
1197 		/* else					~user */
1198 	}
1199 	if (user != NULL) {
1200 		if ((pw = getpwnam(user)) == NULL) {
1201 			error_f("No such user %s", user);
1202 			goto out;
1203 		}
1204 	} else if ((pw = getpwuid(uid)) == NULL) {
1205 		error_f("No such uid %ld", (long)uid);
1206 		goto out;
1207 	}
1208 
1209 	/* Make sure directory has a trailing '/' */
1210 	slash = (len = strlen(pw->pw_dir)) == 0 || pw->pw_dir[len - 1] != '/';
1211 
1212 	if ((r = xasprintf(&s, "%s%s%s", pw->pw_dir,
1213 	    slash ? "/" : "", path != NULL ? path : "")) <= 0) {
1214 		error_f("xasprintf failed");
1215 		goto out;
1216 	}
1217 	if (r >= PATH_MAX) {
1218 		error_f("Path too long");
1219 		goto out;
1220 	}
1221 	/* success */
1222 	ret = 0;
1223 	*retp = s;
1224 	s = NULL;
1225  out:
1226 	free(s);
1227 	free(ocopy);
1228 	return ret;
1229 }
1230 
1231 char *
1232 tilde_expand_filename(const char *filename, uid_t uid)
1233 {
1234 	char *ret;
1235 
1236 	if (tilde_expand(filename, uid, &ret) != 0)
1237 		cleanup_exit(255);
1238 	return ret;
1239 }
1240 
1241 /*
1242  * Expand a string with a set of %[char] escapes and/or ${ENVIRONMENT}
1243  * substitutions.  A number of escapes may be specified as
1244  * (char *escape_chars, char *replacement) pairs. The list must be terminated
1245  * by a NULL escape_char. Returns replaced string in memory allocated by
1246  * xmalloc which the caller must free.
1247  */
1248 static char *
1249 vdollar_percent_expand(int *parseerror, int dollar, int percent,
1250     const char *string, va_list ap)
1251 {
1252 #define EXPAND_MAX_KEYS	64
1253 	u_int num_keys = 0, i;
1254 	struct {
1255 		const char *key;
1256 		const char *repl;
1257 	} keys[EXPAND_MAX_KEYS];
1258 	struct sshbuf *buf;
1259 	int r, missingvar = 0;
1260 	char *ret = NULL, *var, *varend, *val;
1261 	size_t len;
1262 
1263 	if ((buf = sshbuf_new()) == NULL)
1264 		fatal_f("sshbuf_new failed");
1265 	if (parseerror == NULL)
1266 		fatal_f("null parseerror arg");
1267 	*parseerror = 1;
1268 
1269 	/* Gather keys if we're doing percent expansion. */
1270 	if (percent) {
1271 		for (num_keys = 0; num_keys < EXPAND_MAX_KEYS; num_keys++) {
1272 			keys[num_keys].key = va_arg(ap, char *);
1273 			if (keys[num_keys].key == NULL)
1274 				break;
1275 			keys[num_keys].repl = va_arg(ap, char *);
1276 			if (keys[num_keys].repl == NULL) {
1277 				fatal_f("NULL replacement for token %s",
1278 				    keys[num_keys].key);
1279 			}
1280 		}
1281 		if (num_keys == EXPAND_MAX_KEYS && va_arg(ap, char *) != NULL)
1282 			fatal_f("too many keys");
1283 		if (num_keys == 0)
1284 			fatal_f("percent expansion without token list");
1285 	}
1286 
1287 	/* Expand string */
1288 	for (i = 0; *string != '\0'; string++) {
1289 		/* Optionally process ${ENVIRONMENT} expansions. */
1290 		if (dollar && string[0] == '$' && string[1] == '{') {
1291 			string += 2;  /* skip over '${' */
1292 			if ((varend = strchr(string, '}')) == NULL) {
1293 				error_f("environment variable '%s' missing "
1294 				    "closing '}'", string);
1295 				goto out;
1296 			}
1297 			len = varend - string;
1298 			if (len == 0) {
1299 				error_f("zero-length environment variable");
1300 				goto out;
1301 			}
1302 			var = xmalloc(len + 1);
1303 			(void)strlcpy(var, string, len + 1);
1304 			if ((val = getenv(var)) == NULL) {
1305 				error_f("env var ${%s} has no value", var);
1306 				missingvar = 1;
1307 			} else {
1308 				debug3_f("expand ${%s} -> '%s'", var, val);
1309 				if ((r = sshbuf_put(buf, val, strlen(val))) !=0)
1310 					fatal_fr(r, "sshbuf_put ${}");
1311 			}
1312 			free(var);
1313 			string += len;
1314 			continue;
1315 		}
1316 
1317 		/*
1318 		 * Process percent expansions if we have a list of TOKENs.
1319 		 * If we're not doing percent expansion everything just gets
1320 		 * appended here.
1321 		 */
1322 		if (*string != '%' || !percent) {
1323  append:
1324 			if ((r = sshbuf_put_u8(buf, *string)) != 0)
1325 				fatal_fr(r, "sshbuf_put_u8 %%");
1326 			continue;
1327 		}
1328 		string++;
1329 		/* %% case */
1330 		if (*string == '%')
1331 			goto append;
1332 		if (*string == '\0') {
1333 			error_f("invalid format");
1334 			goto out;
1335 		}
1336 		for (i = 0; i < num_keys; i++) {
1337 			if (strchr(keys[i].key, *string) != NULL) {
1338 				if ((r = sshbuf_put(buf, keys[i].repl,
1339 				    strlen(keys[i].repl))) != 0)
1340 					fatal_fr(r, "sshbuf_put %%-repl");
1341 				break;
1342 			}
1343 		}
1344 		if (i >= num_keys) {
1345 			error_f("unknown key %%%c", *string);
1346 			goto out;
1347 		}
1348 	}
1349 	if (!missingvar && (ret = sshbuf_dup_string(buf)) == NULL)
1350 		fatal_f("sshbuf_dup_string failed");
1351 	*parseerror = 0;
1352  out:
1353 	sshbuf_free(buf);
1354 	return *parseerror ? NULL : ret;
1355 #undef EXPAND_MAX_KEYS
1356 }
1357 
1358 /*
1359  * Expand only environment variables.
1360  * Note that although this function is variadic like the other similar
1361  * functions, any such arguments will be unused.
1362  */
1363 
1364 char *
1365 dollar_expand(int *parseerr, const char *string, ...)
1366 {
1367 	char *ret;
1368 	int err;
1369 	va_list ap;
1370 
1371 	va_start(ap, string);
1372 	ret = vdollar_percent_expand(&err, 1, 0, string, ap);
1373 	va_end(ap);
1374 	if (parseerr != NULL)
1375 		*parseerr = err;
1376 	return ret;
1377 }
1378 
1379 /*
1380  * Returns expanded string or NULL if a specified environment variable is
1381  * not defined, or calls fatal if the string is invalid.
1382  */
1383 char *
1384 percent_expand(const char *string, ...)
1385 {
1386 	char *ret;
1387 	int err;
1388 	va_list ap;
1389 
1390 	va_start(ap, string);
1391 	ret = vdollar_percent_expand(&err, 0, 1, string, ap);
1392 	va_end(ap);
1393 	if (err)
1394 		fatal_f("failed");
1395 	return ret;
1396 }
1397 
1398 /*
1399  * Returns expanded string or NULL if a specified environment variable is
1400  * not defined, or calls fatal if the string is invalid.
1401  */
1402 char *
1403 percent_dollar_expand(const char *string, ...)
1404 {
1405 	char *ret;
1406 	int err;
1407 	va_list ap;
1408 
1409 	va_start(ap, string);
1410 	ret = vdollar_percent_expand(&err, 1, 1, string, ap);
1411 	va_end(ap);
1412 	if (err)
1413 		fatal_f("failed");
1414 	return ret;
1415 }
1416 
1417 int
1418 tun_open(int tun, int mode, char **ifname)
1419 {
1420 #if defined(CUSTOM_SYS_TUN_OPEN)
1421 	return (sys_tun_open(tun, mode, ifname));
1422 #elif defined(SSH_TUN_OPENBSD)
1423 	struct ifreq ifr;
1424 	char name[100];
1425 	int fd = -1, sock;
1426 	const char *tunbase = "tun";
1427 
1428 	if (ifname != NULL)
1429 		*ifname = NULL;
1430 
1431 	if (mode == SSH_TUNMODE_ETHERNET)
1432 		tunbase = "tap";
1433 
1434 	/* Open the tunnel device */
1435 	if (tun <= SSH_TUNID_MAX) {
1436 		snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
1437 		fd = open(name, O_RDWR);
1438 	} else if (tun == SSH_TUNID_ANY) {
1439 		for (tun = 100; tun >= 0; tun--) {
1440 			snprintf(name, sizeof(name), "/dev/%s%d",
1441 			    tunbase, tun);
1442 			if ((fd = open(name, O_RDWR)) >= 0)
1443 				break;
1444 		}
1445 	} else {
1446 		debug_f("invalid tunnel %u", tun);
1447 		return -1;
1448 	}
1449 
1450 	if (fd == -1) {
1451 		debug_f("%s open: %s", name, strerror(errno));
1452 		return -1;
1453 	}
1454 
1455 	debug_f("%s mode %d fd %d", name, mode, fd);
1456 
1457 	/* Bring interface up if it is not already */
1458 	snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
1459 	if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
1460 		goto failed;
1461 
1462 	if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1) {
1463 		debug_f("get interface %s flags: %s", ifr.ifr_name,
1464 		    strerror(errno));
1465 		goto failed;
1466 	}
1467 
1468 	if (!(ifr.ifr_flags & IFF_UP)) {
1469 		ifr.ifr_flags |= IFF_UP;
1470 		if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1) {
1471 			debug_f("activate interface %s: %s", ifr.ifr_name,
1472 			    strerror(errno));
1473 			goto failed;
1474 		}
1475 	}
1476 
1477 	if (ifname != NULL)
1478 		*ifname = xstrdup(ifr.ifr_name);
1479 
1480 	close(sock);
1481 	return fd;
1482 
1483  failed:
1484 	if (fd >= 0)
1485 		close(fd);
1486 	if (sock >= 0)
1487 		close(sock);
1488 	return -1;
1489 #else
1490 	error("Tunnel interfaces are not supported on this platform");
1491 	return (-1);
1492 #endif
1493 }
1494 
1495 void
1496 sanitise_stdfd(void)
1497 {
1498 	int nullfd, dupfd;
1499 
1500 	if ((nullfd = dupfd = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1501 		fprintf(stderr, "Couldn't open /dev/null: %s\n",
1502 		    strerror(errno));
1503 		exit(1);
1504 	}
1505 	while (++dupfd <= STDERR_FILENO) {
1506 		/* Only populate closed fds. */
1507 		if (fcntl(dupfd, F_GETFL) == -1 && errno == EBADF) {
1508 			if (dup2(nullfd, dupfd) == -1) {
1509 				fprintf(stderr, "dup2: %s\n", strerror(errno));
1510 				exit(1);
1511 			}
1512 		}
1513 	}
1514 	if (nullfd > STDERR_FILENO)
1515 		close(nullfd);
1516 }
1517 
1518 char *
1519 tohex(const void *vp, size_t l)
1520 {
1521 	const u_char *p = (const u_char *)vp;
1522 	char b[3], *r;
1523 	size_t i, hl;
1524 
1525 	if (l > 65536)
1526 		return xstrdup("tohex: length > 65536");
1527 
1528 	hl = l * 2 + 1;
1529 	r = xcalloc(1, hl);
1530 	for (i = 0; i < l; i++) {
1531 		snprintf(b, sizeof(b), "%02x", p[i]);
1532 		strlcat(r, b, hl);
1533 	}
1534 	return (r);
1535 }
1536 
1537 /*
1538  * Extend string *sp by the specified format. If *sp is not NULL (or empty),
1539  * then the separator 'sep' will be prepended before the formatted arguments.
1540  * Extended strings are heap allocated.
1541  */
1542 void
1543 xextendf(char **sp, const char *sep, const char *fmt, ...)
1544 {
1545 	va_list ap;
1546 	char *tmp1, *tmp2;
1547 
1548 	va_start(ap, fmt);
1549 	xvasprintf(&tmp1, fmt, ap);
1550 	va_end(ap);
1551 
1552 	if (*sp == NULL || **sp == '\0') {
1553 		free(*sp);
1554 		*sp = tmp1;
1555 		return;
1556 	}
1557 	xasprintf(&tmp2, "%s%s%s", *sp, sep == NULL ? "" : sep, tmp1);
1558 	free(tmp1);
1559 	free(*sp);
1560 	*sp = tmp2;
1561 }
1562 
1563 
1564 u_int64_t
1565 get_u64(const void *vp)
1566 {
1567 	const u_char *p = (const u_char *)vp;
1568 	u_int64_t v;
1569 
1570 	v  = (u_int64_t)p[0] << 56;
1571 	v |= (u_int64_t)p[1] << 48;
1572 	v |= (u_int64_t)p[2] << 40;
1573 	v |= (u_int64_t)p[3] << 32;
1574 	v |= (u_int64_t)p[4] << 24;
1575 	v |= (u_int64_t)p[5] << 16;
1576 	v |= (u_int64_t)p[6] << 8;
1577 	v |= (u_int64_t)p[7];
1578 
1579 	return (v);
1580 }
1581 
1582 u_int32_t
1583 get_u32(const void *vp)
1584 {
1585 	const u_char *p = (const u_char *)vp;
1586 	u_int32_t v;
1587 
1588 	v  = (u_int32_t)p[0] << 24;
1589 	v |= (u_int32_t)p[1] << 16;
1590 	v |= (u_int32_t)p[2] << 8;
1591 	v |= (u_int32_t)p[3];
1592 
1593 	return (v);
1594 }
1595 
1596 u_int32_t
1597 get_u32_le(const void *vp)
1598 {
1599 	const u_char *p = (const u_char *)vp;
1600 	u_int32_t v;
1601 
1602 	v  = (u_int32_t)p[0];
1603 	v |= (u_int32_t)p[1] << 8;
1604 	v |= (u_int32_t)p[2] << 16;
1605 	v |= (u_int32_t)p[3] << 24;
1606 
1607 	return (v);
1608 }
1609 
1610 u_int16_t
1611 get_u16(const void *vp)
1612 {
1613 	const u_char *p = (const u_char *)vp;
1614 	u_int16_t v;
1615 
1616 	v  = (u_int16_t)p[0] << 8;
1617 	v |= (u_int16_t)p[1];
1618 
1619 	return (v);
1620 }
1621 
1622 void
1623 put_u64(void *vp, u_int64_t v)
1624 {
1625 	u_char *p = (u_char *)vp;
1626 
1627 	p[0] = (u_char)(v >> 56) & 0xff;
1628 	p[1] = (u_char)(v >> 48) & 0xff;
1629 	p[2] = (u_char)(v >> 40) & 0xff;
1630 	p[3] = (u_char)(v >> 32) & 0xff;
1631 	p[4] = (u_char)(v >> 24) & 0xff;
1632 	p[5] = (u_char)(v >> 16) & 0xff;
1633 	p[6] = (u_char)(v >> 8) & 0xff;
1634 	p[7] = (u_char)v & 0xff;
1635 }
1636 
1637 void
1638 put_u32(void *vp, u_int32_t v)
1639 {
1640 	u_char *p = (u_char *)vp;
1641 
1642 	p[0] = (u_char)(v >> 24) & 0xff;
1643 	p[1] = (u_char)(v >> 16) & 0xff;
1644 	p[2] = (u_char)(v >> 8) & 0xff;
1645 	p[3] = (u_char)v & 0xff;
1646 }
1647 
1648 void
1649 put_u32_le(void *vp, u_int32_t v)
1650 {
1651 	u_char *p = (u_char *)vp;
1652 
1653 	p[0] = (u_char)v & 0xff;
1654 	p[1] = (u_char)(v >> 8) & 0xff;
1655 	p[2] = (u_char)(v >> 16) & 0xff;
1656 	p[3] = (u_char)(v >> 24) & 0xff;
1657 }
1658 
1659 void
1660 put_u16(void *vp, u_int16_t v)
1661 {
1662 	u_char *p = (u_char *)vp;
1663 
1664 	p[0] = (u_char)(v >> 8) & 0xff;
1665 	p[1] = (u_char)v & 0xff;
1666 }
1667 
1668 void
1669 ms_subtract_diff(struct timeval *start, int *ms)
1670 {
1671 	struct timeval diff, finish;
1672 
1673 	monotime_tv(&finish);
1674 	timersub(&finish, start, &diff);
1675 	*ms -= (diff.tv_sec * 1000) + (diff.tv_usec / 1000);
1676 }
1677 
1678 void
1679 ms_to_timespec(struct timespec *ts, int ms)
1680 {
1681 	if (ms < 0)
1682 		ms = 0;
1683 	ts->tv_sec = ms / 1000;
1684 	ts->tv_nsec = (ms % 1000) * 1000 * 1000;
1685 }
1686 
1687 void
1688 monotime_ts(struct timespec *ts)
1689 {
1690 	struct timeval tv;
1691 #if defined(HAVE_CLOCK_GETTIME) && (defined(CLOCK_BOOTTIME) || \
1692     defined(CLOCK_MONOTONIC) || defined(CLOCK_REALTIME))
1693 	static int gettime_failed = 0;
1694 
1695 	if (!gettime_failed) {
1696 # ifdef CLOCK_BOOTTIME
1697 		if (clock_gettime(CLOCK_BOOTTIME, ts) == 0)
1698 			return;
1699 # endif /* CLOCK_BOOTTIME */
1700 # ifdef CLOCK_MONOTONIC
1701 		if (clock_gettime(CLOCK_MONOTONIC, ts) == 0)
1702 			return;
1703 # endif /* CLOCK_MONOTONIC */
1704 # ifdef CLOCK_REALTIME
1705 		/* Not monotonic, but we're almost out of options here. */
1706 		if (clock_gettime(CLOCK_REALTIME, ts) == 0)
1707 			return;
1708 # endif /* CLOCK_REALTIME */
1709 		debug3("clock_gettime: %s", strerror(errno));
1710 		gettime_failed = 1;
1711 	}
1712 #endif /* HAVE_CLOCK_GETTIME && (BOOTTIME || MONOTONIC || REALTIME) */
1713 	gettimeofday(&tv, NULL);
1714 	ts->tv_sec = tv.tv_sec;
1715 	ts->tv_nsec = (long)tv.tv_usec * 1000;
1716 }
1717 
1718 void
1719 monotime_tv(struct timeval *tv)
1720 {
1721 	struct timespec ts;
1722 
1723 	monotime_ts(&ts);
1724 	tv->tv_sec = ts.tv_sec;
1725 	tv->tv_usec = ts.tv_nsec / 1000;
1726 }
1727 
1728 time_t
1729 monotime(void)
1730 {
1731 	struct timespec ts;
1732 
1733 	monotime_ts(&ts);
1734 	return ts.tv_sec;
1735 }
1736 
1737 double
1738 monotime_double(void)
1739 {
1740 	struct timespec ts;
1741 
1742 	monotime_ts(&ts);
1743 	return ts.tv_sec + ((double)ts.tv_nsec / 1000000000);
1744 }
1745 
1746 void
1747 bandwidth_limit_init(struct bwlimit *bw, u_int64_t kbps, size_t buflen)
1748 {
1749 	bw->buflen = buflen;
1750 	bw->rate = kbps;
1751 	bw->thresh = buflen;
1752 	bw->lamt = 0;
1753 	timerclear(&bw->bwstart);
1754 	timerclear(&bw->bwend);
1755 }
1756 
1757 /* Callback from read/write loop to insert bandwidth-limiting delays */
1758 void
1759 bandwidth_limit(struct bwlimit *bw, size_t read_len)
1760 {
1761 	u_int64_t waitlen;
1762 	struct timespec ts, rm;
1763 
1764 	bw->lamt += read_len;
1765 	if (!timerisset(&bw->bwstart)) {
1766 		monotime_tv(&bw->bwstart);
1767 		return;
1768 	}
1769 	if (bw->lamt < bw->thresh)
1770 		return;
1771 
1772 	monotime_tv(&bw->bwend);
1773 	timersub(&bw->bwend, &bw->bwstart, &bw->bwend);
1774 	if (!timerisset(&bw->bwend))
1775 		return;
1776 
1777 	bw->lamt *= 8;
1778 	waitlen = (double)1000000L * bw->lamt / bw->rate;
1779 
1780 	bw->bwstart.tv_sec = waitlen / 1000000L;
1781 	bw->bwstart.tv_usec = waitlen % 1000000L;
1782 
1783 	if (timercmp(&bw->bwstart, &bw->bwend, >)) {
1784 		timersub(&bw->bwstart, &bw->bwend, &bw->bwend);
1785 
1786 		/* Adjust the wait time */
1787 		if (bw->bwend.tv_sec) {
1788 			bw->thresh /= 2;
1789 			if (bw->thresh < bw->buflen / 4)
1790 				bw->thresh = bw->buflen / 4;
1791 		} else if (bw->bwend.tv_usec < 10000) {
1792 			bw->thresh *= 2;
1793 			if (bw->thresh > bw->buflen * 8)
1794 				bw->thresh = bw->buflen * 8;
1795 		}
1796 
1797 		TIMEVAL_TO_TIMESPEC(&bw->bwend, &ts);
1798 		while (nanosleep(&ts, &rm) == -1) {
1799 			if (errno != EINTR)
1800 				break;
1801 			ts = rm;
1802 		}
1803 	}
1804 
1805 	bw->lamt = 0;
1806 	monotime_tv(&bw->bwstart);
1807 }
1808 
1809 /* Make a template filename for mk[sd]temp() */
1810 void
1811 mktemp_proto(char *s, size_t len)
1812 {
1813 	const char *tmpdir;
1814 	int r;
1815 
1816 	if ((tmpdir = getenv("TMPDIR")) != NULL) {
1817 		r = snprintf(s, len, "%s/ssh-XXXXXXXXXXXX", tmpdir);
1818 		if (r > 0 && (size_t)r < len)
1819 			return;
1820 	}
1821 	r = snprintf(s, len, "/tmp/ssh-XXXXXXXXXXXX");
1822 	if (r < 0 || (size_t)r >= len)
1823 		fatal_f("template string too short");
1824 }
1825 
1826 static const struct {
1827 	const char *name;
1828 	int value;
1829 } ipqos[] = {
1830 	{ "none", INT_MAX },		/* can't use 0 here; that's CS0 */
1831 	{ "af11", IPTOS_DSCP_AF11 },
1832 	{ "af12", IPTOS_DSCP_AF12 },
1833 	{ "af13", IPTOS_DSCP_AF13 },
1834 	{ "af21", IPTOS_DSCP_AF21 },
1835 	{ "af22", IPTOS_DSCP_AF22 },
1836 	{ "af23", IPTOS_DSCP_AF23 },
1837 	{ "af31", IPTOS_DSCP_AF31 },
1838 	{ "af32", IPTOS_DSCP_AF32 },
1839 	{ "af33", IPTOS_DSCP_AF33 },
1840 	{ "af41", IPTOS_DSCP_AF41 },
1841 	{ "af42", IPTOS_DSCP_AF42 },
1842 	{ "af43", IPTOS_DSCP_AF43 },
1843 	{ "cs0", IPTOS_DSCP_CS0 },
1844 	{ "cs1", IPTOS_DSCP_CS1 },
1845 	{ "cs2", IPTOS_DSCP_CS2 },
1846 	{ "cs3", IPTOS_DSCP_CS3 },
1847 	{ "cs4", IPTOS_DSCP_CS4 },
1848 	{ "cs5", IPTOS_DSCP_CS5 },
1849 	{ "cs6", IPTOS_DSCP_CS6 },
1850 	{ "cs7", IPTOS_DSCP_CS7 },
1851 	{ "ef", IPTOS_DSCP_EF },
1852 	{ "le", IPTOS_DSCP_LE },
1853 	{ "lowdelay", IPTOS_LOWDELAY },
1854 	{ "throughput", IPTOS_THROUGHPUT },
1855 	{ "reliability", IPTOS_RELIABILITY },
1856 	{ NULL, -1 }
1857 };
1858 
1859 int
1860 parse_ipqos(const char *cp)
1861 {
1862 	u_int i;
1863 	char *ep;
1864 	long val;
1865 
1866 	if (cp == NULL)
1867 		return -1;
1868 	for (i = 0; ipqos[i].name != NULL; i++) {
1869 		if (strcasecmp(cp, ipqos[i].name) == 0)
1870 			return ipqos[i].value;
1871 	}
1872 	/* Try parsing as an integer */
1873 	val = strtol(cp, &ep, 0);
1874 	if (*cp == '\0' || *ep != '\0' || val < 0 || val > 255)
1875 		return -1;
1876 	return val;
1877 }
1878 
1879 const char *
1880 iptos2str(int iptos)
1881 {
1882 	int i;
1883 	static char iptos_str[sizeof "0xff"];
1884 
1885 	for (i = 0; ipqos[i].name != NULL; i++) {
1886 		if (ipqos[i].value == iptos)
1887 			return ipqos[i].name;
1888 	}
1889 	snprintf(iptos_str, sizeof iptos_str, "0x%02x", iptos);
1890 	return iptos_str;
1891 }
1892 
1893 void
1894 lowercase(char *s)
1895 {
1896 	for (; *s; s++)
1897 		*s = tolower((u_char)*s);
1898 }
1899 
1900 int
1901 unix_listener(const char *path, int backlog, int unlink_first)
1902 {
1903 	struct sockaddr_un sunaddr;
1904 	int saved_errno, sock;
1905 
1906 	memset(&sunaddr, 0, sizeof(sunaddr));
1907 	sunaddr.sun_family = AF_UNIX;
1908 	if (strlcpy(sunaddr.sun_path, path,
1909 	    sizeof(sunaddr.sun_path)) >= sizeof(sunaddr.sun_path)) {
1910 		error_f("path \"%s\" too long for Unix domain socket", path);
1911 		errno = ENAMETOOLONG;
1912 		return -1;
1913 	}
1914 
1915 	sock = socket(PF_UNIX, SOCK_STREAM, 0);
1916 	if (sock == -1) {
1917 		saved_errno = errno;
1918 		error_f("socket: %.100s", strerror(errno));
1919 		errno = saved_errno;
1920 		return -1;
1921 	}
1922 	if (unlink_first == 1) {
1923 		if (unlink(path) != 0 && errno != ENOENT)
1924 			error("unlink(%s): %.100s", path, strerror(errno));
1925 	}
1926 	if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1) {
1927 		saved_errno = errno;
1928 		error_f("cannot bind to path %s: %s", path, strerror(errno));
1929 		close(sock);
1930 		errno = saved_errno;
1931 		return -1;
1932 	}
1933 	if (listen(sock, backlog) == -1) {
1934 		saved_errno = errno;
1935 		error_f("cannot listen on path %s: %s", path, strerror(errno));
1936 		close(sock);
1937 		unlink(path);
1938 		errno = saved_errno;
1939 		return -1;
1940 	}
1941 	return sock;
1942 }
1943 
1944 void
1945 sock_set_v6only(int s)
1946 {
1947 #if defined(IPV6_V6ONLY) && !defined(__OpenBSD__)
1948 	int on = 1;
1949 
1950 	debug3("%s: set socket %d IPV6_V6ONLY", __func__, s);
1951 	if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) == -1)
1952 		error("setsockopt IPV6_V6ONLY: %s", strerror(errno));
1953 #endif
1954 }
1955 
1956 /*
1957  * Compares two strings that maybe be NULL. Returns non-zero if strings
1958  * are both NULL or are identical, returns zero otherwise.
1959  */
1960 static int
1961 strcmp_maybe_null(const char *a, const char *b)
1962 {
1963 	if ((a == NULL && b != NULL) || (a != NULL && b == NULL))
1964 		return 0;
1965 	if (a != NULL && strcmp(a, b) != 0)
1966 		return 0;
1967 	return 1;
1968 }
1969 
1970 /*
1971  * Compare two forwards, returning non-zero if they are identical or
1972  * zero otherwise.
1973  */
1974 int
1975 forward_equals(const struct Forward *a, const struct Forward *b)
1976 {
1977 	if (strcmp_maybe_null(a->listen_host, b->listen_host) == 0)
1978 		return 0;
1979 	if (a->listen_port != b->listen_port)
1980 		return 0;
1981 	if (strcmp_maybe_null(a->listen_path, b->listen_path) == 0)
1982 		return 0;
1983 	if (strcmp_maybe_null(a->connect_host, b->connect_host) == 0)
1984 		return 0;
1985 	if (a->connect_port != b->connect_port)
1986 		return 0;
1987 	if (strcmp_maybe_null(a->connect_path, b->connect_path) == 0)
1988 		return 0;
1989 	/* allocated_port and handle are not checked */
1990 	return 1;
1991 }
1992 
1993 /* returns 1 if process is already daemonized, 0 otherwise */
1994 int
1995 daemonized(void)
1996 {
1997 	int fd;
1998 
1999 	if ((fd = open(_PATH_TTY, O_RDONLY | O_NOCTTY)) >= 0) {
2000 		close(fd);
2001 		return 0;	/* have controlling terminal */
2002 	}
2003 	if (getppid() != 1)
2004 		return 0;	/* parent is not init */
2005 	if (getsid(0) != getpid())
2006 		return 0;	/* not session leader */
2007 	debug3("already daemonized");
2008 	return 1;
2009 }
2010 
2011 /*
2012  * Splits 's' into an argument vector. Handles quoted string and basic
2013  * escape characters (\\, \", \'). Caller must free the argument vector
2014  * and its members.
2015  */
2016 int
2017 argv_split(const char *s, int *argcp, char ***argvp, int terminate_on_comment)
2018 {
2019 	int r = SSH_ERR_INTERNAL_ERROR;
2020 	int argc = 0, quote, i, j;
2021 	char *arg, **argv = xcalloc(1, sizeof(*argv));
2022 
2023 	*argvp = NULL;
2024 	*argcp = 0;
2025 
2026 	for (i = 0; s[i] != '\0'; i++) {
2027 		/* Skip leading whitespace */
2028 		if (s[i] == ' ' || s[i] == '\t')
2029 			continue;
2030 		if (terminate_on_comment && s[i] == '#')
2031 			break;
2032 		/* Start of a token */
2033 		quote = 0;
2034 
2035 		argv = xreallocarray(argv, (argc + 2), sizeof(*argv));
2036 		arg = argv[argc++] = xcalloc(1, strlen(s + i) + 1);
2037 		argv[argc] = NULL;
2038 
2039 		/* Copy the token in, removing escapes */
2040 		for (j = 0; s[i] != '\0'; i++) {
2041 			if (s[i] == '\\') {
2042 				if (s[i + 1] == '\'' ||
2043 				    s[i + 1] == '\"' ||
2044 				    s[i + 1] == '\\' ||
2045 				    (quote == 0 && s[i + 1] == ' ')) {
2046 					i++; /* Skip '\' */
2047 					arg[j++] = s[i];
2048 				} else {
2049 					/* Unrecognised escape */
2050 					arg[j++] = s[i];
2051 				}
2052 			} else if (quote == 0 && (s[i] == ' ' || s[i] == '\t'))
2053 				break; /* done */
2054 			else if (quote == 0 && (s[i] == '\"' || s[i] == '\''))
2055 				quote = s[i]; /* quote start */
2056 			else if (quote != 0 && s[i] == quote)
2057 				quote = 0; /* quote end */
2058 			else
2059 				arg[j++] = s[i];
2060 		}
2061 		if (s[i] == '\0') {
2062 			if (quote != 0) {
2063 				/* Ran out of string looking for close quote */
2064 				r = SSH_ERR_INVALID_FORMAT;
2065 				goto out;
2066 			}
2067 			break;
2068 		}
2069 	}
2070 	/* Success */
2071 	*argcp = argc;
2072 	*argvp = argv;
2073 	argc = 0;
2074 	argv = NULL;
2075 	r = 0;
2076  out:
2077 	if (argc != 0 && argv != NULL) {
2078 		for (i = 0; i < argc; i++)
2079 			free(argv[i]);
2080 		free(argv);
2081 	}
2082 	return r;
2083 }
2084 
2085 /*
2086  * Reassemble an argument vector into a string, quoting and escaping as
2087  * necessary. Caller must free returned string.
2088  */
2089 char *
2090 argv_assemble(int argc, char **argv)
2091 {
2092 	int i, j, ws, r;
2093 	char c, *ret;
2094 	struct sshbuf *buf, *arg;
2095 
2096 	if ((buf = sshbuf_new()) == NULL || (arg = sshbuf_new()) == NULL)
2097 		fatal_f("sshbuf_new failed");
2098 
2099 	for (i = 0; i < argc; i++) {
2100 		ws = 0;
2101 		sshbuf_reset(arg);
2102 		for (j = 0; argv[i][j] != '\0'; j++) {
2103 			r = 0;
2104 			c = argv[i][j];
2105 			switch (c) {
2106 			case ' ':
2107 			case '\t':
2108 				ws = 1;
2109 				r = sshbuf_put_u8(arg, c);
2110 				break;
2111 			case '\\':
2112 			case '\'':
2113 			case '"':
2114 				if ((r = sshbuf_put_u8(arg, '\\')) != 0)
2115 					break;
2116 				/* FALLTHROUGH */
2117 			default:
2118 				r = sshbuf_put_u8(arg, c);
2119 				break;
2120 			}
2121 			if (r != 0)
2122 				fatal_fr(r, "sshbuf_put_u8");
2123 		}
2124 		if ((i != 0 && (r = sshbuf_put_u8(buf, ' ')) != 0) ||
2125 		    (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0) ||
2126 		    (r = sshbuf_putb(buf, arg)) != 0 ||
2127 		    (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0))
2128 			fatal_fr(r, "assemble");
2129 	}
2130 	if ((ret = malloc(sshbuf_len(buf) + 1)) == NULL)
2131 		fatal_f("malloc failed");
2132 	memcpy(ret, sshbuf_ptr(buf), sshbuf_len(buf));
2133 	ret[sshbuf_len(buf)] = '\0';
2134 	sshbuf_free(buf);
2135 	sshbuf_free(arg);
2136 	return ret;
2137 }
2138 
2139 char *
2140 argv_next(int *argcp, char ***argvp)
2141 {
2142 	char *ret = (*argvp)[0];
2143 
2144 	if (*argcp > 0 && ret != NULL) {
2145 		(*argcp)--;
2146 		(*argvp)++;
2147 	}
2148 	return ret;
2149 }
2150 
2151 void
2152 argv_consume(int *argcp)
2153 {
2154 	*argcp = 0;
2155 }
2156 
2157 void
2158 argv_free(char **av, int ac)
2159 {
2160 	int i;
2161 
2162 	if (av == NULL)
2163 		return;
2164 	for (i = 0; i < ac; i++)
2165 		free(av[i]);
2166 	free(av);
2167 }
2168 
2169 /* Returns 0 if pid exited cleanly, non-zero otherwise */
2170 int
2171 exited_cleanly(pid_t pid, const char *tag, const char *cmd, int quiet)
2172 {
2173 	int status;
2174 
2175 	while (waitpid(pid, &status, 0) == -1) {
2176 		if (errno != EINTR) {
2177 			error("%s waitpid: %s", tag, strerror(errno));
2178 			return -1;
2179 		}
2180 	}
2181 	if (WIFSIGNALED(status)) {
2182 		error("%s %s exited on signal %d", tag, cmd, WTERMSIG(status));
2183 		return -1;
2184 	} else if (WEXITSTATUS(status) != 0) {
2185 		do_log2(quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_INFO,
2186 		    "%s %s failed, status %d", tag, cmd, WEXITSTATUS(status));
2187 		return -1;
2188 	}
2189 	return 0;
2190 }
2191 
2192 /*
2193  * Check a given path for security. This is defined as all components
2194  * of the path to the file must be owned by either the owner of
2195  * of the file or root and no directories must be group or world writable.
2196  *
2197  * XXX Should any specific check be done for sym links ?
2198  *
2199  * Takes a file name, its stat information (preferably from fstat() to
2200  * avoid races), the uid of the expected owner, their home directory and an
2201  * error buffer plus max size as arguments.
2202  *
2203  * Returns 0 on success and -1 on failure
2204  */
2205 int
2206 safe_path(const char *name, struct stat *stp, const char *pw_dir,
2207     uid_t uid, char *err, size_t errlen)
2208 {
2209 	char buf[PATH_MAX], homedir[PATH_MAX];
2210 	char *cp;
2211 	int comparehome = 0;
2212 	struct stat st;
2213 
2214 	if (realpath(name, buf) == NULL) {
2215 		snprintf(err, errlen, "realpath %s failed: %s", name,
2216 		    strerror(errno));
2217 		return -1;
2218 	}
2219 	if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
2220 		comparehome = 1;
2221 
2222 	if (!S_ISREG(stp->st_mode)) {
2223 		snprintf(err, errlen, "%s is not a regular file", buf);
2224 		return -1;
2225 	}
2226 	if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
2227 	    (stp->st_mode & 022) != 0) {
2228 		snprintf(err, errlen, "bad ownership or modes for file %s",
2229 		    buf);
2230 		return -1;
2231 	}
2232 
2233 	/* for each component of the canonical path, walking upwards */
2234 	for (;;) {
2235 		if ((cp = dirname(buf)) == NULL) {
2236 			snprintf(err, errlen, "dirname() failed");
2237 			return -1;
2238 		}
2239 		strlcpy(buf, cp, sizeof(buf));
2240 
2241 		if (stat(buf, &st) == -1 ||
2242 		    (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
2243 		    (st.st_mode & 022) != 0) {
2244 			snprintf(err, errlen,
2245 			    "bad ownership or modes for directory %s", buf);
2246 			return -1;
2247 		}
2248 
2249 		/* If are past the homedir then we can stop */
2250 		if (comparehome && strcmp(homedir, buf) == 0)
2251 			break;
2252 
2253 		/*
2254 		 * dirname should always complete with a "/" path,
2255 		 * but we can be paranoid and check for "." too
2256 		 */
2257 		if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
2258 			break;
2259 	}
2260 	return 0;
2261 }
2262 
2263 /*
2264  * Version of safe_path() that accepts an open file descriptor to
2265  * avoid races.
2266  *
2267  * Returns 0 on success and -1 on failure
2268  */
2269 int
2270 safe_path_fd(int fd, const char *file, struct passwd *pw,
2271     char *err, size_t errlen)
2272 {
2273 	struct stat st;
2274 
2275 	/* check the open file to avoid races */
2276 	if (fstat(fd, &st) == -1) {
2277 		snprintf(err, errlen, "cannot stat file %s: %s",
2278 		    file, strerror(errno));
2279 		return -1;
2280 	}
2281 	return safe_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
2282 }
2283 
2284 /*
2285  * Sets the value of the given variable in the environment.  If the variable
2286  * already exists, its value is overridden.
2287  */
2288 void
2289 child_set_env(char ***envp, u_int *envsizep, const char *name,
2290 	const char *value)
2291 {
2292 	char **env;
2293 	u_int envsize;
2294 	u_int i, namelen;
2295 
2296 	if (strchr(name, '=') != NULL) {
2297 		error("Invalid environment variable \"%.100s\"", name);
2298 		return;
2299 	}
2300 
2301 	/*
2302 	 * If we're passed an uninitialized list, allocate a single null
2303 	 * entry before continuing.
2304 	 */
2305 	if ((*envp == NULL) != (*envsizep == 0))
2306 		fatal_f("environment size mismatch");
2307 	if (*envp == NULL && *envsizep == 0) {
2308 		*envp = xmalloc(sizeof(char *));
2309 		*envp[0] = NULL;
2310 		*envsizep = 1;
2311 	}
2312 
2313 	/*
2314 	 * Find the slot where the value should be stored.  If the variable
2315 	 * already exists, we reuse the slot; otherwise we append a new slot
2316 	 * at the end of the array, expanding if necessary.
2317 	 */
2318 	env = *envp;
2319 	namelen = strlen(name);
2320 	for (i = 0; env[i]; i++)
2321 		if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
2322 			break;
2323 	if (env[i]) {
2324 		/* Reuse the slot. */
2325 		free(env[i]);
2326 	} else {
2327 		/* New variable.  Expand if necessary. */
2328 		envsize = *envsizep;
2329 		if (i >= envsize - 1) {
2330 			if (envsize >= 1000)
2331 				fatal("child_set_env: too many env vars");
2332 			envsize += 50;
2333 			env = (*envp) = xreallocarray(env, envsize, sizeof(char *));
2334 			*envsizep = envsize;
2335 		}
2336 		/* Need to set the NULL pointer at end of array beyond the new slot. */
2337 		env[i + 1] = NULL;
2338 	}
2339 
2340 	/* Allocate space and format the variable in the appropriate slot. */
2341 	/* XXX xasprintf */
2342 	env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
2343 	snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
2344 }
2345 
2346 /*
2347  * Check and optionally lowercase a domain name, also removes trailing '.'
2348  * Returns 1 on success and 0 on failure, storing an error message in errstr.
2349  */
2350 int
2351 valid_domain(char *name, int makelower, const char **errstr)
2352 {
2353 	size_t i, l = strlen(name);
2354 	u_char c, last = '\0';
2355 	static char errbuf[256];
2356 
2357 	if (l == 0) {
2358 		strlcpy(errbuf, "empty domain name", sizeof(errbuf));
2359 		goto bad;
2360 	}
2361 	if (!isalpha((u_char)name[0]) && !isdigit((u_char)name[0])) {
2362 		snprintf(errbuf, sizeof(errbuf), "domain name \"%.100s\" "
2363 		    "starts with invalid character", name);
2364 		goto bad;
2365 	}
2366 	for (i = 0; i < l; i++) {
2367 		c = tolower((u_char)name[i]);
2368 		if (makelower)
2369 			name[i] = (char)c;
2370 		if (last == '.' && c == '.') {
2371 			snprintf(errbuf, sizeof(errbuf), "domain name "
2372 			    "\"%.100s\" contains consecutive separators", name);
2373 			goto bad;
2374 		}
2375 		if (c != '.' && c != '-' && !isalnum(c) &&
2376 		    c != '_') /* technically invalid, but common */ {
2377 			snprintf(errbuf, sizeof(errbuf), "domain name "
2378 			    "\"%.100s\" contains invalid characters", name);
2379 			goto bad;
2380 		}
2381 		last = c;
2382 	}
2383 	if (name[l - 1] == '.')
2384 		name[l - 1] = '\0';
2385 	if (errstr != NULL)
2386 		*errstr = NULL;
2387 	return 1;
2388 bad:
2389 	if (errstr != NULL)
2390 		*errstr = errbuf;
2391 	return 0;
2392 }
2393 
2394 /*
2395  * Verify that a environment variable name (not including initial '$') is
2396  * valid; consisting of one or more alphanumeric or underscore characters only.
2397  * Returns 1 on valid, 0 otherwise.
2398  */
2399 int
2400 valid_env_name(const char *name)
2401 {
2402 	const char *cp;
2403 
2404 	if (name[0] == '\0')
2405 		return 0;
2406 	for (cp = name; *cp != '\0'; cp++) {
2407 		if (!isalnum((u_char)*cp) && *cp != '_')
2408 			return 0;
2409 	}
2410 	return 1;
2411 }
2412 
2413 const char *
2414 atoi_err(const char *nptr, int *val)
2415 {
2416 	const char *errstr = NULL;
2417 	long long num;
2418 
2419 	if (nptr == NULL || *nptr == '\0')
2420 		return "missing";
2421 	num = strtonum(nptr, 0, INT_MAX, &errstr);
2422 	if (errstr == NULL)
2423 		*val = (int)num;
2424 	return errstr;
2425 }
2426 
2427 int
2428 parse_absolute_time(const char *s, uint64_t *tp)
2429 {
2430 	struct tm tm;
2431 	time_t tt;
2432 	char buf[32], *fmt;
2433 	const char *cp;
2434 	size_t l;
2435 	int is_utc = 0;
2436 
2437 	*tp = 0;
2438 
2439 	l = strlen(s);
2440 	if (l > 1 && strcasecmp(s + l - 1, "Z") == 0) {
2441 		is_utc = 1;
2442 		l--;
2443 	} else if (l > 3 && strcasecmp(s + l - 3, "UTC") == 0) {
2444 		is_utc = 1;
2445 		l -= 3;
2446 	}
2447 	/*
2448 	 * POSIX strptime says "The application shall ensure that there
2449 	 * is white-space or other non-alphanumeric characters between
2450 	 * any two conversion specifications" so arrange things this way.
2451 	 */
2452 	switch (l) {
2453 	case 8: /* YYYYMMDD */
2454 		fmt = "%Y-%m-%d";
2455 		snprintf(buf, sizeof(buf), "%.4s-%.2s-%.2s", s, s + 4, s + 6);
2456 		break;
2457 	case 12: /* YYYYMMDDHHMM */
2458 		fmt = "%Y-%m-%dT%H:%M";
2459 		snprintf(buf, sizeof(buf), "%.4s-%.2s-%.2sT%.2s:%.2s",
2460 		    s, s + 4, s + 6, s + 8, s + 10);
2461 		break;
2462 	case 14: /* YYYYMMDDHHMMSS */
2463 		fmt = "%Y-%m-%dT%H:%M:%S";
2464 		snprintf(buf, sizeof(buf), "%.4s-%.2s-%.2sT%.2s:%.2s:%.2s",
2465 		    s, s + 4, s + 6, s + 8, s + 10, s + 12);
2466 		break;
2467 	default:
2468 		return SSH_ERR_INVALID_FORMAT;
2469 	}
2470 
2471 	memset(&tm, 0, sizeof(tm));
2472 	if ((cp = strptime(buf, fmt, &tm)) == NULL || *cp != '\0')
2473 		return SSH_ERR_INVALID_FORMAT;
2474 	if (is_utc) {
2475 		if ((tt = timegm(&tm)) < 0)
2476 			return SSH_ERR_INVALID_FORMAT;
2477 	} else {
2478 		if ((tt = mktime(&tm)) < 0)
2479 			return SSH_ERR_INVALID_FORMAT;
2480 	}
2481 	/* success */
2482 	*tp = (uint64_t)tt;
2483 	return 0;
2484 }
2485 
2486 void
2487 format_absolute_time(uint64_t t, char *buf, size_t len)
2488 {
2489 	time_t tt = t > SSH_TIME_T_MAX ? SSH_TIME_T_MAX : t;
2490 	struct tm tm;
2491 
2492 	localtime_r(&tt, &tm);
2493 	strftime(buf, len, "%Y-%m-%dT%H:%M:%S", &tm);
2494 }
2495 
2496 /*
2497  * Parse a "pattern=interval" clause (e.g. a ChannelTimeout).
2498  * Returns 0 on success or non-zero on failure.
2499  * Caller must free *typep.
2500  */
2501 int
2502 parse_pattern_interval(const char *s, char **typep, int *secsp)
2503 {
2504 	char *cp, *sdup;
2505 	int secs;
2506 
2507 	if (typep != NULL)
2508 		*typep = NULL;
2509 	if (secsp != NULL)
2510 		*secsp = 0;
2511 	if (s == NULL)
2512 		return -1;
2513 	sdup = xstrdup(s);
2514 
2515 	if ((cp = strchr(sdup, '=')) == NULL || cp == sdup) {
2516 		free(sdup);
2517 		return -1;
2518 	}
2519 	*cp++ = '\0';
2520 	if ((secs = convtime(cp)) < 0) {
2521 		free(sdup);
2522 		return -1;
2523 	}
2524 	/* success */
2525 	if (typep != NULL)
2526 		*typep = xstrdup(sdup);
2527 	if (secsp != NULL)
2528 		*secsp = secs;
2529 	free(sdup);
2530 	return 0;
2531 }
2532 
2533 /* check if path is absolute */
2534 int
2535 path_absolute(const char *path)
2536 {
2537 	return (*path == '/') ? 1 : 0;
2538 }
2539 
2540 void
2541 skip_space(char **cpp)
2542 {
2543 	char *cp;
2544 
2545 	for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
2546 		;
2547 	*cpp = cp;
2548 }
2549 
2550 /* authorized_key-style options parsing helpers */
2551 
2552 /*
2553  * Match flag 'opt' in *optsp, and if allow_negate is set then also match
2554  * 'no-opt'. Returns -1 if option not matched, 1 if option matches or 0
2555  * if negated option matches.
2556  * If the option or negated option matches, then *optsp is updated to
2557  * point to the first character after the option.
2558  */
2559 int
2560 opt_flag(const char *opt, int allow_negate, const char **optsp)
2561 {
2562 	size_t opt_len = strlen(opt);
2563 	const char *opts = *optsp;
2564 	int negate = 0;
2565 
2566 	if (allow_negate && strncasecmp(opts, "no-", 3) == 0) {
2567 		opts += 3;
2568 		negate = 1;
2569 	}
2570 	if (strncasecmp(opts, opt, opt_len) == 0) {
2571 		*optsp = opts + opt_len;
2572 		return negate ? 0 : 1;
2573 	}
2574 	return -1;
2575 }
2576 
2577 char *
2578 opt_dequote(const char **sp, const char **errstrp)
2579 {
2580 	const char *s = *sp;
2581 	char *ret;
2582 	size_t i;
2583 
2584 	*errstrp = NULL;
2585 	if (*s != '"') {
2586 		*errstrp = "missing start quote";
2587 		return NULL;
2588 	}
2589 	s++;
2590 	if ((ret = malloc(strlen((s)) + 1)) == NULL) {
2591 		*errstrp = "memory allocation failed";
2592 		return NULL;
2593 	}
2594 	for (i = 0; *s != '\0' && *s != '"';) {
2595 		if (s[0] == '\\' && s[1] == '"')
2596 			s++;
2597 		ret[i++] = *s++;
2598 	}
2599 	if (*s == '\0') {
2600 		*errstrp = "missing end quote";
2601 		free(ret);
2602 		return NULL;
2603 	}
2604 	ret[i] = '\0';
2605 	s++;
2606 	*sp = s;
2607 	return ret;
2608 }
2609 
2610 int
2611 opt_match(const char **opts, const char *term)
2612 {
2613 	if (strncasecmp((*opts), term, strlen(term)) == 0 &&
2614 	    (*opts)[strlen(term)] == '=') {
2615 		*opts += strlen(term) + 1;
2616 		return 1;
2617 	}
2618 	return 0;
2619 }
2620 
2621 void
2622 opt_array_append2(const char *file, const int line, const char *directive,
2623     char ***array, int **iarray, u_int *lp, const char *s, int i)
2624 {
2625 
2626 	if (*lp >= INT_MAX)
2627 		fatal("%s line %d: Too many %s entries", file, line, directive);
2628 
2629 	if (iarray != NULL) {
2630 		*iarray = xrecallocarray(*iarray, *lp, *lp + 1,
2631 		    sizeof(**iarray));
2632 		(*iarray)[*lp] = i;
2633 	}
2634 
2635 	*array = xrecallocarray(*array, *lp, *lp + 1, sizeof(**array));
2636 	(*array)[*lp] = xstrdup(s);
2637 	(*lp)++;
2638 }
2639 
2640 void
2641 opt_array_append(const char *file, const int line, const char *directive,
2642     char ***array, u_int *lp, const char *s)
2643 {
2644 	opt_array_append2(file, line, directive, array, NULL, lp, s, 0);
2645 }
2646 
2647 sshsig_t
2648 ssh_signal(int signum, sshsig_t handler)
2649 {
2650 	struct sigaction sa, osa;
2651 
2652 	/* mask all other signals while in handler */
2653 	memset(&sa, 0, sizeof(sa));
2654 	sa.sa_handler = handler;
2655 	sigfillset(&sa.sa_mask);
2656 #if defined(SA_RESTART) && !defined(NO_SA_RESTART)
2657 	if (signum != SIGALRM)
2658 		sa.sa_flags = SA_RESTART;
2659 #endif
2660 	if (sigaction(signum, &sa, &osa) == -1) {
2661 		debug3("sigaction(%s): %s", strsignal(signum), strerror(errno));
2662 		return SIG_ERR;
2663 	}
2664 	return osa.sa_handler;
2665 }
2666 
2667 int
2668 stdfd_devnull(int do_stdin, int do_stdout, int do_stderr)
2669 {
2670 	int devnull, ret = 0;
2671 
2672 	if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
2673 		error_f("open %s: %s", _PATH_DEVNULL,
2674 		    strerror(errno));
2675 		return -1;
2676 	}
2677 	if ((do_stdin && dup2(devnull, STDIN_FILENO) == -1) ||
2678 	    (do_stdout && dup2(devnull, STDOUT_FILENO) == -1) ||
2679 	    (do_stderr && dup2(devnull, STDERR_FILENO) == -1)) {
2680 		error_f("dup2: %s", strerror(errno));
2681 		ret = -1;
2682 	}
2683 	if (devnull > STDERR_FILENO)
2684 		close(devnull);
2685 	return ret;
2686 }
2687 
2688 /*
2689  * Runs command in a subprocess with a minimal environment.
2690  * Returns pid on success, 0 on failure.
2691  * The child stdout and stderr maybe captured, left attached or sent to
2692  * /dev/null depending on the contents of flags.
2693  * "tag" is prepended to log messages.
2694  * NB. "command" is only used for logging; the actual command executed is
2695  * av[0].
2696  */
2697 pid_t
2698 subprocess(const char *tag, const char *command,
2699     int ac, char **av, FILE **child, u_int flags,
2700     struct passwd *pw, privdrop_fn *drop_privs, privrestore_fn *restore_privs)
2701 {
2702 	FILE *f = NULL;
2703 	struct stat st;
2704 	int fd, devnull, p[2], i;
2705 	pid_t pid;
2706 	char *cp, errmsg[512];
2707 	u_int nenv = 0;
2708 	char **env = NULL;
2709 
2710 	/* If dropping privs, then must specify user and restore function */
2711 	if (drop_privs != NULL && (pw == NULL || restore_privs == NULL)) {
2712 		error("%s: inconsistent arguments", tag); /* XXX fatal? */
2713 		return 0;
2714 	}
2715 	if (pw == NULL && (pw = getpwuid(getuid())) == NULL) {
2716 		error("%s: no user for current uid", tag);
2717 		return 0;
2718 	}
2719 	if (child != NULL)
2720 		*child = NULL;
2721 
2722 	debug3_f("%s command \"%s\" running as %s (flags 0x%x)",
2723 	    tag, command, pw->pw_name, flags);
2724 
2725 	/* Check consistency */
2726 	if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
2727 	    (flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) {
2728 		error_f("inconsistent flags");
2729 		return 0;
2730 	}
2731 	if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) {
2732 		error_f("inconsistent flags/output");
2733 		return 0;
2734 	}
2735 
2736 	/*
2737 	 * If executing an explicit binary, then verify the it exists
2738 	 * and appears safe-ish to execute
2739 	 */
2740 	if (!path_absolute(av[0])) {
2741 		error("%s path is not absolute", tag);
2742 		return 0;
2743 	}
2744 	if (drop_privs != NULL)
2745 		drop_privs(pw);
2746 	if (stat(av[0], &st) == -1) {
2747 		error("Could not stat %s \"%s\": %s", tag,
2748 		    av[0], strerror(errno));
2749 		goto restore_return;
2750 	}
2751 	if ((flags & SSH_SUBPROCESS_UNSAFE_PATH) == 0 &&
2752 	    safe_path(av[0], &st, NULL, 0, errmsg, sizeof(errmsg)) != 0) {
2753 		error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
2754 		goto restore_return;
2755 	}
2756 	/* Prepare to keep the child's stdout if requested */
2757 	if (pipe(p) == -1) {
2758 		error("%s: pipe: %s", tag, strerror(errno));
2759  restore_return:
2760 		if (restore_privs != NULL)
2761 			restore_privs();
2762 		return 0;
2763 	}
2764 	if (restore_privs != NULL)
2765 		restore_privs();
2766 
2767 	switch ((pid = fork())) {
2768 	case -1: /* error */
2769 		error("%s: fork: %s", tag, strerror(errno));
2770 		close(p[0]);
2771 		close(p[1]);
2772 		return 0;
2773 	case 0: /* child */
2774 		/* Prepare a minimal environment for the child. */
2775 		if ((flags & SSH_SUBPROCESS_PRESERVE_ENV) == 0) {
2776 			nenv = 5;
2777 			env = xcalloc(sizeof(*env), nenv);
2778 			child_set_env(&env, &nenv, "PATH", _PATH_STDPATH);
2779 			child_set_env(&env, &nenv, "USER", pw->pw_name);
2780 			child_set_env(&env, &nenv, "LOGNAME", pw->pw_name);
2781 			child_set_env(&env, &nenv, "HOME", pw->pw_dir);
2782 			if ((cp = getenv("LANG")) != NULL)
2783 				child_set_env(&env, &nenv, "LANG", cp);
2784 		}
2785 
2786 		for (i = 1; i < NSIG; i++)
2787 			ssh_signal(i, SIG_DFL);
2788 
2789 		if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
2790 			error("%s: open %s: %s", tag, _PATH_DEVNULL,
2791 			    strerror(errno));
2792 			_exit(1);
2793 		}
2794 		if (dup2(devnull, STDIN_FILENO) == -1) {
2795 			error("%s: dup2: %s", tag, strerror(errno));
2796 			_exit(1);
2797 		}
2798 
2799 		/* Set up stdout as requested; leave stderr in place for now. */
2800 		fd = -1;
2801 		if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0)
2802 			fd = p[1];
2803 		else if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0)
2804 			fd = devnull;
2805 		if (fd != -1 && dup2(fd, STDOUT_FILENO) == -1) {
2806 			error("%s: dup2: %s", tag, strerror(errno));
2807 			_exit(1);
2808 		}
2809 		closefrom(STDERR_FILENO + 1);
2810 
2811 		if (geteuid() == 0 &&
2812 		    initgroups(pw->pw_name, pw->pw_gid) == -1) {
2813 			error("%s: initgroups(%s, %u): %s", tag,
2814 			    pw->pw_name, (u_int)pw->pw_gid, strerror(errno));
2815 			_exit(1);
2816 		}
2817 		if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1) {
2818 			error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
2819 			    strerror(errno));
2820 			_exit(1);
2821 		}
2822 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1) {
2823 			error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
2824 			    strerror(errno));
2825 			_exit(1);
2826 		}
2827 		/* stdin is pointed to /dev/null at this point */
2828 		if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
2829 		    dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
2830 			error("%s: dup2: %s", tag, strerror(errno));
2831 			_exit(1);
2832 		}
2833 		if (env != NULL)
2834 			execve(av[0], av, env);
2835 		else
2836 			execv(av[0], av);
2837 		error("%s %s \"%s\": %s", tag, env == NULL ? "execv" : "execve",
2838 		    command, strerror(errno));
2839 		_exit(127);
2840 	default: /* parent */
2841 		break;
2842 	}
2843 
2844 	close(p[1]);
2845 	if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0)
2846 		close(p[0]);
2847 	else if ((f = fdopen(p[0], "r")) == NULL) {
2848 		error("%s: fdopen: %s", tag, strerror(errno));
2849 		close(p[0]);
2850 		/* Don't leave zombie child */
2851 		kill(pid, SIGTERM);
2852 		while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
2853 			;
2854 		return 0;
2855 	}
2856 	/* Success */
2857 	debug3_f("%s pid %ld", tag, (long)pid);
2858 	if (child != NULL)
2859 		*child = f;
2860 	return pid;
2861 }
2862 
2863 const char *
2864 lookup_env_in_list(const char *env, char * const *envs, size_t nenvs)
2865 {
2866 	size_t i, envlen;
2867 
2868 	envlen = strlen(env);
2869 	for (i = 0; i < nenvs; i++) {
2870 		if (strncmp(envs[i], env, envlen) == 0 &&
2871 		    envs[i][envlen] == '=') {
2872 			return envs[i] + envlen + 1;
2873 		}
2874 	}
2875 	return NULL;
2876 }
2877 
2878 const char *
2879 lookup_setenv_in_list(const char *env, char * const *envs, size_t nenvs)
2880 {
2881 	char *name, *cp;
2882 	const char *ret;
2883 
2884 	name = xstrdup(env);
2885 	if ((cp = strchr(name, '=')) == NULL) {
2886 		free(name);
2887 		return NULL; /* not env=val */
2888 	}
2889 	*cp = '\0';
2890 	ret = lookup_env_in_list(name, envs, nenvs);
2891 	free(name);
2892 	return ret;
2893 }
2894 
2895 /*
2896  * Helpers for managing poll(2)/ppoll(2) timeouts
2897  * Will remember the earliest deadline and return it for use in poll/ppoll.
2898  */
2899 
2900 /* Initialise a poll/ppoll timeout with an indefinite deadline */
2901 void
2902 ptimeout_init(struct timespec *pt)
2903 {
2904 	/*
2905 	 * Deliberately invalid for ppoll(2).
2906 	 * Will be converted to NULL in ptimeout_get_tspec() later.
2907 	 */
2908 	pt->tv_sec = -1;
2909 	pt->tv_nsec = 0;
2910 }
2911 
2912 /* Specify a poll/ppoll deadline of at most 'sec' seconds */
2913 void
2914 ptimeout_deadline_sec(struct timespec *pt, long sec)
2915 {
2916 	if (pt->tv_sec == -1 || pt->tv_sec >= sec) {
2917 		pt->tv_sec = sec;
2918 		pt->tv_nsec = 0;
2919 	}
2920 }
2921 
2922 /* Specify a poll/ppoll deadline of at most 'p' (timespec) */
2923 static void
2924 ptimeout_deadline_tsp(struct timespec *pt, struct timespec *p)
2925 {
2926 	if (pt->tv_sec == -1 || timespeccmp(pt, p, >=))
2927 		*pt = *p;
2928 }
2929 
2930 /* Specify a poll/ppoll deadline of at most 'ms' milliseconds */
2931 void
2932 ptimeout_deadline_ms(struct timespec *pt, long ms)
2933 {
2934 	struct timespec p;
2935 
2936 	p.tv_sec = ms / 1000;
2937 	p.tv_nsec = (ms % 1000) * 1000000;
2938 	ptimeout_deadline_tsp(pt, &p);
2939 }
2940 
2941 /* Specify a poll/ppoll deadline at wall clock monotime 'when' (timespec) */
2942 void
2943 ptimeout_deadline_monotime_tsp(struct timespec *pt, struct timespec *when)
2944 {
2945 	struct timespec now, t;
2946 
2947 	monotime_ts(&now);
2948 
2949 	if (timespeccmp(&now, when, >=)) {
2950 		/* 'when' is now or in the past. Timeout ASAP */
2951 		pt->tv_sec = 0;
2952 		pt->tv_nsec = 0;
2953 	} else {
2954 		timespecsub(when, &now, &t);
2955 		ptimeout_deadline_tsp(pt, &t);
2956 	}
2957 }
2958 
2959 /* Specify a poll/ppoll deadline at wall clock monotime 'when' */
2960 void
2961 ptimeout_deadline_monotime(struct timespec *pt, time_t when)
2962 {
2963 	struct timespec t;
2964 
2965 	t.tv_sec = when;
2966 	t.tv_nsec = 0;
2967 	ptimeout_deadline_monotime_tsp(pt, &t);
2968 }
2969 
2970 /* Get a poll(2) timeout value in milliseconds */
2971 int
2972 ptimeout_get_ms(struct timespec *pt)
2973 {
2974 	if (pt->tv_sec == -1)
2975 		return -1;
2976 	if (pt->tv_sec >= (INT_MAX - (pt->tv_nsec / 1000000)) / 1000)
2977 		return INT_MAX;
2978 	return (pt->tv_sec * 1000) + (pt->tv_nsec / 1000000);
2979 }
2980 
2981 /* Get a ppoll(2) timeout value as a timespec pointer */
2982 struct timespec *
2983 ptimeout_get_tsp(struct timespec *pt)
2984 {
2985 	return pt->tv_sec == -1 ? NULL : pt;
2986 }
2987 
2988 /* Returns non-zero if a timeout has been set (i.e. is not indefinite) */
2989 int
2990 ptimeout_isset(struct timespec *pt)
2991 {
2992 	return pt->tv_sec != -1;
2993 }
2994 
2995 /*
2996  * Returns zero if the library at 'path' contains symbol 's', nonzero
2997  * otherwise.
2998  */
2999 int
3000 lib_contains_symbol(const char *path, const char *s)
3001 {
3002 #ifdef HAVE_NLIST_H
3003 	struct nlist nl[2];
3004 	int ret = -1, r;
3005 
3006 	memset(nl, 0, sizeof(nl));
3007 	nl[0].n_name = xstrdup(s);
3008 	nl[1].n_name = NULL;
3009 	if ((r = nlist(path, nl)) == -1) {
3010 		error_f("nlist failed for %s", path);
3011 		goto out;
3012 	}
3013 	if (r != 0 || nl[0].n_value == 0 || nl[0].n_type == 0) {
3014 		error_f("library %s does not contain symbol %s", path, s);
3015 		goto out;
3016 	}
3017 	/* success */
3018 	ret = 0;
3019  out:
3020 	free(nl[0].n_name);
3021 	return ret;
3022 #else /* HAVE_NLIST_H */
3023 	int fd, ret = -1;
3024 	struct stat st;
3025 	void *m = NULL;
3026 	size_t sz = 0;
3027 
3028 	memset(&st, 0, sizeof(st));
3029 	if ((fd = open(path, O_RDONLY)) < 0) {
3030 		error_f("open %s: %s", path, strerror(errno));
3031 		return -1;
3032 	}
3033 	if (fstat(fd, &st) != 0) {
3034 		error_f("fstat %s: %s", path, strerror(errno));
3035 		goto out;
3036 	}
3037 	if (!S_ISREG(st.st_mode)) {
3038 		error_f("%s is not a regular file", path);
3039 		goto out;
3040 	}
3041 	if (st.st_size < 0 ||
3042 	    (size_t)st.st_size < strlen(s) ||
3043 	    st.st_size >= INT_MAX/2) {
3044 		error_f("%s bad size %lld", path, (long long)st.st_size);
3045 		goto out;
3046 	}
3047 	sz = (size_t)st.st_size;
3048 	if ((m = mmap(NULL, sz, PROT_READ, MAP_PRIVATE, fd, 0)) == MAP_FAILED ||
3049 	    m == NULL) {
3050 		error_f("mmap %s: %s", path, strerror(errno));
3051 		goto out;
3052 	}
3053 	if (memmem(m, sz, s, strlen(s)) == NULL) {
3054 		error_f("%s does not contain expected string %s", path, s);
3055 		goto out;
3056 	}
3057 	/* success */
3058 	ret = 0;
3059  out:
3060 	if (m != NULL && m != MAP_FAILED)
3061 		munmap(m, sz);
3062 	close(fd);
3063 	return ret;
3064 #endif /* HAVE_NLIST_H */
3065 }
3066