xref: /freebsd/libexec/tftpd/tftpd.c (revision 5138a20765c76cdc8f245d3d7caeffe9a9011bb2)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1983, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 /*
33  * Trivial file transfer protocol server.
34  *
35  * This version includes many modifications by Jim Guyton
36  * <guyton@rand-unix>.
37  */
38 
39 #include <sys/param.h>
40 #include <sys/ioctl.h>
41 #include <sys/socket.h>
42 #include <sys/stat.h>
43 #include <sys/time.h>
44 
45 #include <netinet/in.h>
46 #include <arpa/tftp.h>
47 
48 #include <ctype.h>
49 #include <errno.h>
50 #include <fcntl.h>
51 #include <netdb.h>
52 #include <pwd.h>
53 #include <stdint.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <syslog.h>
58 #include <time.h>
59 #include <unistd.h>
60 
61 #include "tftp-file.h"
62 #include "tftp-io.h"
63 #include "tftp-utils.h"
64 #include "tftp-transfer.h"
65 #include "tftp-options.h"
66 
67 #ifdef	LIBWRAP
68 #include <tcpd.h>
69 #endif
70 
71 static void	tftp_wrq(int peer, char *, size_t);
72 static void	tftp_rrq(int peer, char *, size_t);
73 
74 /*
75  * Null-terminated directory prefix list for absolute pathname requests and
76  * search list for relative pathname requests.
77  *
78  * MAXDIRS should be at least as large as the number of arguments that
79  * inetd allows (currently 20).
80  */
81 #define MAXDIRS	20
82 static struct dirlist {
83 	const char	*name;
84 	size_t		len;
85 } dirs[MAXDIRS+1];
86 static int	suppress_naks;
87 static int	logging;
88 static int	ipchroot;
89 static int	check_woth = 1;
90 static int	create_new = 0;
91 static const char *newfile_format = "%Y%m%d";
92 static int	increase_name = 0;
93 static mode_t	mask = S_IWGRP | S_IWOTH;
94 
95 struct formats;
96 static void	tftp_recvfile(int peer, const char *mode);
97 static void	tftp_xmitfile(int peer, const char *mode);
98 static int	validate_access(int peer, char **, int);
99 static char	peername[NI_MAXHOST];
100 
101 static FILE *file;
102 
103 static struct formats {
104 	const char	*f_mode;
105 	int	f_convert;
106 } formats[] = {
107 	{ "netascii",	1 },
108 	{ "octet",	0 },
109 	{ NULL,		0 }
110 };
111 
112 int
main(int argc,char * argv[])113 main(int argc, char *argv[])
114 {
115 	struct tftphdr *tp;
116 	int		peer;
117 	socklen_t	peerlen, len;
118 	ssize_t		n;
119 	int		ch;
120 	char		*chroot_dir = NULL;
121 	struct passwd	*nobody;
122 	const char	*chuser = "nobody";
123 	char		recvbuffer[MAXPKTSIZE];
124 	int		allow_ro = 1, allow_wo = 1, block = 0, on = 1;
125 	pid_t		pid;
126 
127 	tzset();			/* syslog in localtime */
128 	acting_as_client = 0;
129 
130 	tftp_openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
131 	while ((ch = getopt(argc, argv, "bcCd::F:lnoOp:s:Su:U:wW")) != -1) {
132 		switch (ch) {
133 		case 'b':
134 			block = 1;
135 			break;
136 		case 'c':
137 			ipchroot = 1;
138 			break;
139 		case 'C':
140 			ipchroot = 2;
141 			break;
142 		case 'd':
143 			if (optarg == NULL)
144 				debug++;
145 			else if (atoi(optarg) != 0)
146 				debug += atoi(optarg);
147 			else
148 				debug |= debug_finds(optarg);
149 			break;
150 		case 'F':
151 			newfile_format = optarg;
152 			break;
153 		case 'l':
154 			logging = 1;
155 			break;
156 		case 'n':
157 			suppress_naks = 1;
158 			break;
159 		case 'o':
160 			options_rfc_enabled = 0;
161 			break;
162 		case 'O':
163 			options_extra_enabled = 0;
164 			break;
165 		case 'p':
166 			packetdroppercentage = (unsigned int)atoi(optarg);
167 			tftp_log(LOG_INFO,
168 			    "Randomly dropping %d out of 100 packets",
169 			    packetdroppercentage);
170 			break;
171 		case 's':
172 			chroot_dir = optarg;
173 			break;
174 		case 'S':
175 			check_woth = -1;
176 			break;
177 		case 'u':
178 			chuser = optarg;
179 			break;
180 		case 'U':
181 			mask = strtol(optarg, NULL, 0);
182 			break;
183 		case 'w':
184 			create_new = 1;
185 			break;
186 		case 'W':
187 			create_new = 1;
188 			increase_name = 1;
189 			break;
190 		default:
191 			tftp_log(LOG_WARNING,
192 				"ignoring unknown option -%c", ch);
193 		}
194 	}
195 	if (optind < argc) {
196 		struct dirlist *dirp;
197 
198 		/* Get list of directory prefixes. Skip relative pathnames. */
199 		for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
200 		     optind++) {
201 			if (argv[optind][0] == '/') {
202 				dirp->name = argv[optind];
203 				dirp->len  = strlen(dirp->name);
204 				dirp++;
205 			}
206 		}
207 	}
208 	else if (chroot_dir) {
209 		dirs->name = "/";
210 		dirs->len = 1;
211 	}
212 	if (ipchroot > 0 && chroot_dir == NULL) {
213 		tftp_log(LOG_ERR, "-c requires -s");
214 		exit(1);
215 	}
216 
217 	umask(mask);
218 
219 	/* Find out who we are talking to and what we are going to do */
220 	peerlen = sizeof(peer_sock);
221 	n = recvfrom(0, recvbuffer, MAXPKTSIZE, block ? 0 : MSG_DONTWAIT,
222 	    (struct sockaddr *)&peer_sock, &peerlen);
223 	if (n < 0) {
224 		tftp_log(LOG_ERR, "recvfrom: %s", strerror(errno));
225 		exit(1);
226 	}
227 	getnameinfo((struct sockaddr *)&peer_sock, peer_sock.ss_len,
228 	    peername, sizeof(peername), NULL, 0, NI_NUMERICHOST);
229 	if ((size_t)n < 4 /* tftphdr */) {
230 		tftp_log(LOG_ERR, "Rejecting %zd-byte request from %s",
231 		    n, peername);
232 		exit(1);
233 	}
234 
235 	if (ioctl(0, FIONBIO, &on) < 0) {
236 		tftp_log(LOG_ERR, "ioctl(FIONBIO): %s", strerror(errno));
237 		exit(1);
238 	}
239 
240 	/*
241 	 * Now that we have read the message out of the UDP
242 	 * socket, we fork and exit.  Thus, inetd will go back
243 	 * to listening to the tftp port, and the next request
244 	 * to come in will start up a new instance of tftpd.
245 	 *
246 	 * We do this so that inetd can run tftpd in "wait" mode.
247 	 * The problem with tftpd running in "nowait" mode is that
248 	 * inetd may get one or more successful "selects" on the
249 	 * tftp port before we do our receive, so more than one
250 	 * instance of tftpd may be started up.  Worse, if tftpd
251 	 * break before doing the above "recvfrom", inetd would
252 	 * spawn endless instances, clogging the system.
253 	 */
254 	pid = fork();
255 	if (pid < 0) {
256 		tftp_log(LOG_ERR, "fork: %s", strerror(errno));
257 		exit(1);
258 	} else if (pid != 0) {
259 		exit(0);
260 	}
261 	/* child */
262 
263 #ifdef	LIBWRAP
264 	/*
265 	 * See if the client is allowed to talk to me.
266 	 * (This needs to be done before the chroot())
267 	 */
268 	{
269 		struct request_info req;
270 
271 		request_init(&req, RQ_CLIENT_ADDR, peername, 0);
272 		request_set(&req, RQ_DAEMON, "tftpd", 0);
273 
274 		if (hosts_access(&req) == 0) {
275 			if (debug & DEBUG_ACCESS)
276 				tftp_log(LOG_WARNING,
277 				    "Access denied by 'tftpd' entry "
278 				    "in /etc/hosts.allow");
279 
280 			/*
281 			 * Full access might be disabled, but maybe the
282 			 * client is allowed to do read-only access.
283 			 */
284 			request_set(&req, RQ_DAEMON, "tftpd-ro", 0);
285 			allow_ro = hosts_access(&req);
286 
287 			request_set(&req, RQ_DAEMON, "tftpd-wo", 0);
288 			allow_wo = hosts_access(&req);
289 
290 			if (allow_ro == 0 && allow_wo == 0) {
291 				tftp_log(LOG_WARNING,
292 				    "Unauthorized access from %s", peername);
293 				exit(1);
294 			}
295 
296 			if (debug & DEBUG_ACCESS) {
297 				if (allow_ro)
298 					tftp_log(LOG_WARNING,
299 					    "But allowed readonly access "
300 					    "via 'tftpd-ro' entry");
301 				if (allow_wo)
302 					tftp_log(LOG_WARNING,
303 					    "But allowed writeonly access "
304 					    "via 'tftpd-wo' entry");
305 			}
306 		} else
307 			if (debug & DEBUG_ACCESS)
308 				tftp_log(LOG_WARNING,
309 				    "Full access allowed"
310 				    "in /etc/hosts.allow");
311 	}
312 #endif
313 
314 	/*
315 	 * Since we exit here, we should do that only after the above
316 	 * recvfrom to keep inetd from constantly forking should there
317 	 * be a problem.  See the above comment about system clogging.
318 	 */
319 	if (chroot_dir) {
320 		if (ipchroot > 0) {
321 			char *tempchroot;
322 			struct stat sb;
323 			int statret;
324 			struct sockaddr_storage ss;
325 			char hbuf[NI_MAXHOST];
326 
327 			statret = -1;
328 			memcpy(&ss, &peer_sock, peer_sock.ss_len);
329 			unmappedaddr((struct sockaddr_in6 *)&ss);
330 			getnameinfo((struct sockaddr *)&ss, ss.ss_len,
331 				    hbuf, sizeof(hbuf), NULL, 0,
332 				    NI_NUMERICHOST);
333 			asprintf(&tempchroot, "%s/%s", chroot_dir, hbuf);
334 			if (ipchroot == 2)
335 				statret = stat(tempchroot, &sb);
336 			if (ipchroot == 1 ||
337 			    (statret == 0 && (sb.st_mode & S_IFDIR)))
338 				chroot_dir = tempchroot;
339 		}
340 		/* Must get this before chroot because /etc might go away */
341 		if ((nobody = getpwnam(chuser)) == NULL) {
342 			tftp_log(LOG_ERR, "%s: no such user", chuser);
343 			exit(1);
344 		}
345 		if (chroot(chroot_dir)) {
346 			tftp_log(LOG_ERR, "chroot: %s: %s",
347 			    chroot_dir, strerror(errno));
348 			exit(1);
349 		}
350 		if (chdir("/") != 0) {
351 			tftp_log(LOG_ERR, "chdir: %s", strerror(errno));
352 			exit(1);
353 		}
354 		if (setgroups(0, NULL) != 0) {
355 			tftp_log(LOG_ERR, "setgroups failed");
356 			exit(1);
357 		}
358 		if (setgid(nobody->pw_gid) != 0) {
359 			tftp_log(LOG_ERR, "setgid failed");
360 			exit(1);
361 		}
362 		if (setuid(nobody->pw_uid) != 0) {
363 			tftp_log(LOG_ERR, "setuid failed");
364 			exit(1);
365 		}
366 		if (check_woth == -1)
367 			check_woth = 0;
368 	}
369 	if (check_woth == -1)
370 		check_woth = 1;
371 
372 	len = sizeof(me_sock);
373 	if (getsockname(0, (struct sockaddr *)&me_sock, &len) == 0) {
374 		switch (me_sock.ss_family) {
375 		case AF_INET:
376 			((struct sockaddr_in *)&me_sock)->sin_port = 0;
377 			break;
378 		case AF_INET6:
379 			((struct sockaddr_in6 *)&me_sock)->sin6_port = 0;
380 			break;
381 		default:
382 			/* unsupported */
383 			break;
384 		}
385 	} else {
386 		memset(&me_sock, 0, sizeof(me_sock));
387 		me_sock.ss_family = peer_sock.ss_family;
388 		me_sock.ss_len = peer_sock.ss_len;
389 	}
390 	close(STDIN_FILENO);
391 	close(STDOUT_FILENO);
392 	close(STDERR_FILENO);
393 	peer = socket(peer_sock.ss_family, SOCK_DGRAM, 0);
394 	if (peer < 0) {
395 		tftp_log(LOG_ERR, "socket: %s", strerror(errno));
396 		exit(1);
397 	}
398 	if (bind(peer, (struct sockaddr *)&me_sock, me_sock.ss_len) < 0) {
399 		tftp_log(LOG_ERR, "bind: %s", strerror(errno));
400 		exit(1);
401 	}
402 
403 	tp = (struct tftphdr *)recvbuffer;
404 	tp->th_opcode = ntohs(tp->th_opcode);
405 	if (tp->th_opcode == RRQ) {
406 		if (allow_ro)
407 			tftp_rrq(peer, tp->th_stuff, (size_t)n - 1);
408 		else {
409 			tftp_log(LOG_WARNING,
410 			    "%s read access denied", peername);
411 			exit(1);
412 		}
413 	} else if (tp->th_opcode == WRQ) {
414 		if (allow_wo)
415 			tftp_wrq(peer, tp->th_stuff, (size_t)n - 1);
416 		else {
417 			tftp_log(LOG_WARNING,
418 			    "%s write access denied", peername);
419 			exit(1);
420 		}
421 	} else
422 		send_error(peer, EBADOP);
423 	exit(1);
424 }
425 
426 static void
reduce_path(char * fn)427 reduce_path(char *fn)
428 {
429 	char *slash, *ptr;
430 
431 	/* Reduce all "/+./" to "/" (just in case we've got "/./../" later */
432 	while ((slash = strstr(fn, "/./")) != NULL) {
433 		for (ptr = slash; ptr > fn && ptr[-1] == '/'; ptr--)
434 			;
435 		slash += 2;
436 		while (*slash)
437 			*++ptr = *++slash;
438 	}
439 
440 	/* Now reduce all "/something/+../" to "/" */
441 	while ((slash = strstr(fn, "/../")) != NULL) {
442 		if (slash == fn)
443 			break;
444 		for (ptr = slash; ptr > fn && ptr[-1] == '/'; ptr--)
445 			;
446 		for (ptr--; ptr >= fn; ptr--)
447 			if (*ptr == '/')
448 				break;
449 		if (ptr < fn)
450 			break;
451 		slash += 3;
452 		while (*slash)
453 			*++ptr = *++slash;
454 	}
455 }
456 
457 static char *
parse_header(int peer,char * recvbuffer,size_t size,char ** filename,char ** mode)458 parse_header(int peer, char *recvbuffer, size_t size,
459 	char **filename, char **mode)
460 {
461 	struct formats *pf;
462 	char	*cp;
463 	size_t	i;
464 
465 	*mode = NULL;
466 	cp = recvbuffer;
467 
468 	i = get_field(peer, recvbuffer, size);
469 	if (i >= PATH_MAX) {
470 		tftp_log(LOG_ERR, "Bad option - filename too long");
471 		send_error(peer, EBADOP);
472 		exit(1);
473 	}
474 	*filename = recvbuffer;
475 	tftp_log(LOG_INFO, "Filename: '%s'", *filename);
476 	cp += i;
477 
478 	i = get_field(peer, cp, size);
479 	*mode = cp;
480 
481 	/* Find the file transfer mode */
482 	for (; *cp; cp++)
483 		if (isupper((unsigned char)*cp))
484 			*cp = tolower((unsigned char)*cp);
485 	for (pf = formats; pf->f_mode; pf++)
486 		if (strcmp(pf->f_mode, *mode) == 0)
487 			break;
488 	if (pf->f_mode == NULL) {
489 		tftp_log(LOG_ERR,
490 		    "Bad option - Unknown transfer mode (%s)", *mode);
491 		send_error(peer, EBADOP);
492 		exit(1);
493 	}
494 	tftp_log(LOG_INFO, "Mode: '%s'", *mode);
495 
496 	return (cp + 1);
497 }
498 
499 /*
500  * WRQ - receive a file from the client
501  */
502 void
tftp_wrq(int peer,char * recvbuffer,size_t size)503 tftp_wrq(int peer, char *recvbuffer, size_t size)
504 {
505 	char *cp;
506 	int has_options = 0, ecode;
507 	char *filename, *mode;
508 	char fnbuf[PATH_MAX];
509 
510 	cp = parse_header(peer, recvbuffer, size, &filename, &mode);
511 	size -= (cp - recvbuffer) + 1;
512 
513 	strlcpy(fnbuf, filename, sizeof(fnbuf));
514 	reduce_path(fnbuf);
515 	filename = fnbuf;
516 
517 	if (size > 0) {
518 		if (options_rfc_enabled)
519 			has_options = !parse_options(peer, cp, size);
520 		else
521 			tftp_log(LOG_INFO, "Options found but not enabled");
522 	}
523 
524 	ecode = validate_access(peer, &filename, WRQ);
525 	if (ecode == 0) {
526 		if (has_options)
527 			send_oack(peer);
528 		else
529 			send_ack(peer, 0);
530 	}
531 	if (logging) {
532 		tftp_log(LOG_INFO, "%s: write request for %s: %s", peername,
533 			    filename, errtomsg(ecode));
534 	}
535 
536 	if (ecode) {
537 		send_error(peer, ecode);
538 		exit(1);
539 	}
540 	tftp_recvfile(peer, mode);
541 	exit(0);
542 }
543 
544 /*
545  * RRQ - send a file to the client
546  */
547 void
tftp_rrq(int peer,char * recvbuffer,size_t size)548 tftp_rrq(int peer, char *recvbuffer, size_t size)
549 {
550 	char *cp;
551 	int has_options = 0, ecode;
552 	char *filename, *mode;
553 	char	fnbuf[PATH_MAX];
554 
555 	cp = parse_header(peer, recvbuffer, size, &filename, &mode);
556 	size -= (cp - recvbuffer) + 1;
557 
558 	strlcpy(fnbuf, filename, sizeof(fnbuf));
559 	reduce_path(fnbuf);
560 	filename = fnbuf;
561 
562 	if (size > 0) {
563 		if (options_rfc_enabled)
564 			has_options = !parse_options(peer, cp, size);
565 		else
566 			tftp_log(LOG_INFO, "Options found but not enabled");
567 	}
568 
569 	ecode = validate_access(peer, &filename, RRQ);
570 	if (ecode == 0) {
571 		if (has_options) {
572 			int n;
573 			char lrecvbuffer[MAXPKTSIZE];
574 			struct tftphdr *rp = (struct tftphdr *)lrecvbuffer;
575 
576 			send_oack(peer);
577 			n = receive_packet(peer, lrecvbuffer, MAXPKTSIZE,
578 				NULL, timeoutpacket);
579 			if (n < 0) {
580 				if (debug & DEBUG_SIMPLE)
581 					tftp_log(LOG_DEBUG, "Aborting: %s",
582 					    rp_strerror(n));
583 				return;
584 			}
585 			if (rp->th_opcode != ACK) {
586 				if (debug & DEBUG_SIMPLE)
587 					tftp_log(LOG_DEBUG,
588 					    "Expected ACK, got %s on OACK",
589 					    packettype(rp->th_opcode));
590 				return;
591 			}
592 		}
593 	}
594 
595 	if (logging)
596 		tftp_log(LOG_INFO, "%s: read request for %s: %s", peername,
597 			    filename, errtomsg(ecode));
598 
599 	if (ecode) {
600 		/*
601 		 * Avoid storms of naks to a RRQ broadcast for a relative
602 		 * bootfile pathname from a diskless Sun.
603 		 */
604 		if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
605 			exit(0);
606 		send_error(peer, ecode);
607 		exit(1);
608 	}
609 	tftp_xmitfile(peer, mode);
610 }
611 
612 /*
613  * Find the next value for YYYYMMDD.nn when the file to be written should
614  * be unique. Due to the limitations of nn, we will fail if nn reaches 100.
615  * Besides, that is four updates per hour on a file, which is kind of
616  * execessive anyway.
617  */
618 static int
find_next_name(char * filename,int * fd)619 find_next_name(char *filename, int *fd)
620 {
621 	/*
622 	 * GCC "knows" that we might write all of yyyymmdd plus the static
623 	 * elemenents in the format into into newname and thus complains
624 	 * unless we reduce the size.  This array is still too big, but since
625 	 * the format is user supplied, it's not clear what a better limit
626 	 * value would be and this is sufficent to silence the warnings.
627 	 */
628 	static const int suffix_len = strlen("..00");
629 	char yyyymmdd[MAXPATHLEN - suffix_len];
630 	char newname[MAXPATHLEN];
631 	int i, ret;
632 	time_t tval;
633 	size_t len, namelen;
634 	struct tm lt;
635 
636 	/* Create the YYYYMMDD part of the filename */
637 	time(&tval);
638 	lt = *localtime(&tval);
639 	len = strftime(yyyymmdd, sizeof(yyyymmdd), newfile_format, &lt);
640 	if (len == 0) {
641 		syslog(LOG_WARNING,
642 			"Filename suffix too long (%zu characters maximum)",
643 			sizeof(yyyymmdd) - 1);
644 		return (EACCESS);
645 	}
646 
647 	/* Make sure the new filename is not too long */
648 	namelen = strlen(filename);
649 	if (namelen >= sizeof(newname) - len - suffix_len) {
650 		syslog(LOG_WARNING,
651 			"Filename too long (%zu characters, %zu maximum)",
652 			namelen,
653 			sizeof(newname) - len - suffix_len - 1);
654 		return (EACCESS);
655 	}
656 
657 	/* Find the first file which doesn't exist */
658 	for (i = 0; i < 100; i++) {
659 		ret = snprintf(newname, sizeof(newname), "%s.%s.%02d",
660 		    filename, yyyymmdd, i);
661 		/*
662 		 * Size checked above so this can't happen, we'd use a
663 		 * (void) cast, but gcc intentionally ignores that if
664 		 * snprintf has __attribute__((warn_unused_result)).
665 		 */
666 		if (ret < 0 || (size_t)ret >= sizeof(newname))
667 			__unreachable();
668 		*fd = open(newname, O_WRONLY | O_CREAT | O_EXCL, 0666);
669 		if (*fd > 0)
670 			return 0;
671 	}
672 
673 	return (EEXIST);
674 }
675 
676 /*
677  * Validate file access.  Since we
678  * have no uid or gid, for now require
679  * file to exist and be publicly
680  * readable/writable.
681  * If we were invoked with arguments
682  * from inetd then the file must also be
683  * in one of the given directory prefixes.
684  * Note also, full path name must be
685  * given as we have no login directory.
686  */
687 int
validate_access(int peer,char ** filep,int mode)688 validate_access(int peer, char **filep, int mode)
689 {
690 	static char pathname[MAXPATHLEN];
691 	struct stat sb;
692 	struct dirlist *dirp;
693 	char *filename = *filep;
694 	int	err, fd;
695 
696 	/*
697 	 * Prevent tricksters from getting around the directory restrictions
698 	 */
699 	if (strncmp(filename, "../", 3) == 0 ||
700 	    strstr(filename, "/../") != NULL)
701 		return (EACCESS);
702 
703 	if (*filename == '/') {
704 		/*
705 		 * Absolute file name: allow the request if it's in one of the
706 		 * approved locations.
707 		 */
708 		for (dirp = dirs; dirp->name != NULL; dirp++) {
709 			if (dirp->len == 1)
710 				/* Only "/" can have len 1 */
711 				break;
712 			if (strncmp(filename, dirp->name, dirp->len) == 0 &&
713 			    filename[dirp->len] == '/')
714 				break;
715 		}
716 		/* If directory list is empty, allow access to any file */
717 		if (dirp->name == NULL && dirp != dirs)
718 			return (EACCESS);
719 		if (stat(filename, &sb) != 0)
720 			return (errno == ENOENT ? ENOTFOUND : EACCESS);
721 		if (!S_ISREG(sb.st_mode))
722 			return (ENOTFOUND);
723 		if (mode == RRQ) {
724 			if ((sb.st_mode & S_IROTH) == 0)
725 				return (EACCESS);
726 		} else {
727 			if (check_woth && (sb.st_mode & S_IWOTH) == 0)
728 				return (EACCESS);
729 		}
730 	} else {
731 		/*
732 		 * Relative file name: search the approved locations for it.
733 		 * If the file exists in one of the directories and isn't
734 		 * readable, continue looking. However, change the error code
735 		 * to give an indication that the file exists.
736 		 */
737 		err = ENOTFOUND;
738 		for (dirp = dirs; dirp->name != NULL; dirp++) {
739 			snprintf(pathname, sizeof(pathname), "%s/%s",
740 			    dirp->name, filename);
741 			if (stat(pathname, &sb) != 0)
742 				continue;
743 			if (!S_ISREG(sb.st_mode))
744 				continue;
745 			err = EACCESS;
746 			if (mode == RRQ) {
747 				if ((sb.st_mode & S_IROTH) == 0)
748 					continue;
749 			} else {
750 				if (check_woth && (sb.st_mode & S_IWOTH) == 0)
751 					continue;
752 			}
753 			break;
754 		}
755 		if (dirp->name != NULL)
756 			*filep = filename = pathname;
757 		else if (mode == RRQ)
758 			return (err);
759 		else if (err != ENOTFOUND || !create_new)
760 			return (err);
761 	}
762 
763 	/*
764 	 * This option is handled here because it (might) require(s) the
765 	 * size of the file.
766 	 */
767 	option_tsize(peer, NULL, mode, &sb);
768 
769 	if (mode == RRQ) {
770 		fd = open(filename, O_RDONLY);
771 	} else if (create_new) {
772 		if (increase_name) {
773 			err = find_next_name(filename, &fd);
774 			if (err > 0)
775 				return (err + 100);
776 		} else {
777 			fd = open(filename,
778 			    O_WRONLY | O_TRUNC | O_CREAT,
779 			    S_IRUSR | S_IWUSR | S_IRGRP |
780 			    S_IWGRP | S_IROTH | S_IWOTH );
781 		}
782 	} else {
783 		fd = open(filename, O_WRONLY | O_TRUNC);
784 	}
785 	if (fd < 0)
786 		return (errno + 100);
787 	file = fdopen(fd, mode == RRQ ? "r" : "w");
788 	if (file == NULL) {
789 		close(fd);
790 		return (errno + 100);
791 	}
792 	return (0);
793 }
794 
795 static void
tftp_xmitfile(int peer,const char * mode)796 tftp_xmitfile(int peer, const char *mode)
797 {
798 	uint16_t block;
799 	time_t now;
800 	struct tftp_stats ts;
801 
802 	memset(&ts, 0, sizeof(ts));
803 	now = time(NULL);
804 	if (debug & DEBUG_SIMPLE)
805 		tftp_log(LOG_DEBUG, "Transmitting file");
806 
807 	read_init(0, file, mode);
808 	block = 1;
809 	tftp_send(peer, &block, &ts);
810 	read_close();
811 	if (debug & DEBUG_SIMPLE)
812 		tftp_log(LOG_INFO, "Sent %jd bytes in %jd seconds",
813 		    (intmax_t)ts.amount, (intmax_t)time(NULL) - now);
814 }
815 
816 static void
tftp_recvfile(int peer,const char * mode)817 tftp_recvfile(int peer, const char *mode)
818 {
819 	uint16_t block;
820 	struct timeval now1, now2;
821 	struct tftp_stats ts;
822 
823 	gettimeofday(&now1, NULL);
824 	if (debug & DEBUG_SIMPLE)
825 		tftp_log(LOG_DEBUG, "Receiving file");
826 
827 	write_init(0, file, mode);
828 
829 	block = 0;
830 	tftp_receive(peer, &block, &ts, NULL, 0);
831 
832 	gettimeofday(&now2, NULL);
833 
834 	if (debug & DEBUG_SIMPLE) {
835 		double f;
836 		if (now1.tv_usec > now2.tv_usec) {
837 			now2.tv_usec += 1000000;
838 			now2.tv_sec--;
839 		}
840 
841 		f = now2.tv_sec - now1.tv_sec +
842 		    (now2.tv_usec - now1.tv_usec) / 100000.0;
843 		tftp_log(LOG_INFO,
844 		    "Download of %jd bytes in %d blocks completed after %0.1f seconds\n",
845 		    (intmax_t)ts.amount, block, f);
846 	}
847 
848 	return;
849 }
850