2 * Copyright (c) 1983, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 static const char copyright[] =
36 "@(#) Copyright (c) 1983, 1993\n\
37 The Regents of the University of California. All rights reserved.\n";
42 static char sccsid[] = "@(#)tftpd.c 8.1 (Berkeley) 6/4/93";
44 static const char rcsid[] =
49 * Trivial file transfer protocol server.
51 * This version includes many modifications by Jim Guyton
55 #include <sys/param.h>
56 #include <sys/ioctl.h>
58 #include <sys/socket.h>
59 #include <sys/types.h>
61 #include <netinet/in.h>
62 #include <arpa/tftp.h>
63 #include <arpa/inet.h>
82 #define MAX_TIMEOUTS 5
85 int rexmtval = TIMEOUT;
86 int max_rexmtval = 2*TIMEOUT;
88 #define PKTSIZE SEGSIZE+4
91 struct sockaddr_in from;
94 void tftp __P((struct tftphdr *, int));
97 * Null-terminated directory prefix list for absolute pathname requests and
98 * search list for relative pathname requests.
100 * MAXDIRS should be at least as large as the number of arguments that
101 * inetd allows (currently 20).
104 static struct dirlist {
108 static int suppress_naks;
112 static char *errtomsg __P((int));
113 static void nak __P((int));
114 static void oack __P(());
121 register struct tftphdr *tp;
124 struct sockaddr_in sin;
125 char *chroot_dir = NULL;
126 struct passwd *nobody;
127 char *chuser = "nobody";
129 openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
130 while ((ch = getopt(argc, argv, "cClns:u:")) != -1) {
151 syslog(LOG_WARNING, "ignoring unknown option -%c", ch);
155 struct dirlist *dirp;
157 /* Get list of directory prefixes. Skip relative pathnames. */
158 for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
160 if (argv[optind][0] == '/') {
161 dirp->name = argv[optind];
162 dirp->len = strlen(dirp->name);
167 else if (chroot_dir) {
171 if (ipchroot && chroot_dir == NULL) {
172 syslog(LOG_ERR, "-c requires -s");
177 if (ioctl(0, FIONBIO, &on) < 0) {
178 syslog(LOG_ERR, "ioctl(FIONBIO): %m");
181 fromlen = sizeof (from);
182 n = recvfrom(0, buf, sizeof (buf), 0,
183 (struct sockaddr *)&from, &fromlen);
185 syslog(LOG_ERR, "recvfrom: %m");
189 * Now that we have read the message out of the UDP
190 * socket, we fork and exit. Thus, inetd will go back
191 * to listening to the tftp port, and the next request
192 * to come in will start up a new instance of tftpd.
194 * We do this so that inetd can run tftpd in "wait" mode.
195 * The problem with tftpd running in "nowait" mode is that
196 * inetd may get one or more successful "selects" on the
197 * tftp port before we do our receive, so more than one
198 * instance of tftpd may be started up. Worse, if tftpd
199 * break before doing the above "recvfrom", inetd would
200 * spawn endless instances, clogging the system.
206 for (i = 1; i < 20; i++) {
211 * flush out to most recently sent request.
213 * This may drop some request, but those
214 * will be resent by the clients when
215 * they timeout. The positive effect of
216 * this flush is to (try to) prevent more
217 * than one tftpd being started up to service
218 * a single request from a single client.
221 i = recvfrom(0, buf, sizeof (buf), 0,
222 (struct sockaddr *)&from, &j);
232 syslog(LOG_ERR, "fork: %m");
234 } else if (pid != 0) {
240 * Since we exit here, we should do that only after the above
241 * recvfrom to keep inetd from constantly forking should there
242 * be a problem. See the above comment about system clogging.
250 tempchroot = inet_ntoa(from.sin_addr);
251 asprintf(&tempchroot, "%s/%s", chroot_dir, tempchroot);
252 statret = stat(tempchroot, &sb);
253 if ((sb.st_mode & S_IFDIR) &&
254 (statret == 0 || (statret == -1 && ipchroot == 1)))
255 chroot_dir = tempchroot;
257 /* Must get this before chroot because /etc might go away */
258 if ((nobody = getpwnam(chuser)) == NULL) {
259 syslog(LOG_ERR, "%s: no such user", chuser);
262 if (chroot(chroot_dir)) {
263 syslog(LOG_ERR, "chroot: %s: %m", chroot_dir);
267 setuid(nobody->pw_uid);
268 setgroups(1, &nobody->pw_gid);
271 from.sin_family = AF_INET;
275 peer = socket(AF_INET, SOCK_DGRAM, 0);
277 syslog(LOG_ERR, "socket: %m");
280 memset(&sin, 0, sizeof(sin));
281 sin.sin_family = AF_INET;
282 if (bind(peer, (struct sockaddr *)&sin, sizeof (sin)) < 0) {
283 syslog(LOG_ERR, "bind: %m");
286 if (connect(peer, (struct sockaddr *)&from, sizeof(from)) < 0) {
287 syslog(LOG_ERR, "connect: %m");
290 tp = (struct tftphdr *)buf;
291 tp->th_opcode = ntohs(tp->th_opcode);
292 if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
298 int validate_access __P((char **, int));
299 void xmitfile __P((struct formats *));
300 void recvfile __P((struct formats *));
304 int (*f_validate) __P((char **, int));
305 void (*f_send) __P((struct formats *));
306 void (*f_recv) __P((struct formats *));
309 { "netascii", validate_access, xmitfile, recvfile, 1 },
310 { "octet", validate_access, xmitfile, recvfile, 0 },
312 { "mail", validate_user, sendmail, recvmail, 1 },
320 int o_reply; /* turn into union if need be */
322 { "tsize" }, /* OPT_TSIZE */
323 { "timeout" }, /* OPT_TIMEOUT */
333 * Handle initial connection protocol.
341 int i, first = 1, has_options = 0, ecode;
342 register struct formats *pf;
343 char *filename, *mode, *option, *ccp;
345 filename = cp = tp->th_stuff;
347 while (cp < buf + size) {
361 for (cp = mode; *cp; cp++)
364 for (pf = formats; pf->f_mode; pf++)
365 if (strcmp(pf->f_mode, mode) == 0)
367 if (pf->f_mode == 0) {
371 while (++cp < buf + size) {
372 for (i = 2, ccp = cp; i > 0; ccp++) {
373 if (ccp >= buf + size) {
375 * Don't reject the request, just stop trying
376 * to parse the option and get on with it.
377 * Some Apple OpenFirmware versions have
378 * trailing garbage on the end of otherwise
382 } else if (*ccp == '\0')
385 for (option = cp; *cp; cp++)
388 for (i = 0; options[i].o_type != NULL; i++)
389 if (strcmp(option, options[i].o_type) == 0) {
390 options[i].o_request = ++cp;
397 if (options[OPT_TIMEOUT].o_request) {
398 int to = atoi(options[OPT_TIMEOUT].o_request);
399 if (to < 1 || to > 255) {
403 else if (to <= max_rexmtval)
404 options[OPT_TIMEOUT].o_reply = rexmtval = to;
406 options[OPT_TIMEOUT].o_request = NULL;
409 ecode = (*pf->f_validate)(&filename, tp->th_opcode);
413 char host[MAXHOSTNAMELEN];
415 realhostname(host, sizeof(host) - 1, &from.sin_addr);
416 host[sizeof(host) - 1] = '\0';
417 syslog(LOG_INFO, "%s: %s request for %s: %s", host,
418 tp->th_opcode == WRQ ? "write" : "read",
419 filename, errtomsg(ecode));
423 * Avoid storms of naks to a RRQ broadcast for a relative
424 * bootfile pathname from a diskless Sun.
426 if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
431 if (tp->th_opcode == WRQ)
442 * Validate file access. Since we
443 * have no uid or gid, for now require
444 * file to exist and be publicly
446 * If we were invoked with arguments
447 * from inetd then the file must also be
448 * in one of the given directory prefixes.
449 * Note also, full path name must be
450 * given as we have no login directory.
453 validate_access(filep, mode)
459 struct dirlist *dirp;
460 static char pathname[MAXPATHLEN];
461 char *filename = *filep;
464 * Prevent tricksters from getting around the directory restrictions
466 if (strstr(filename, "/../"))
469 if (*filename == '/') {
471 * Allow the request if it's in one of the approved locations.
472 * Special case: check the null prefix ("/") by looking
473 * for length = 1 and relying on the arg. processing that
476 for (dirp = dirs; dirp->name != NULL; dirp++) {
477 if (dirp->len == 1 ||
478 (!strncmp(filename, dirp->name, dirp->len) &&
479 filename[dirp->len] == '/'))
482 /* If directory list is empty, allow access to any file */
483 if (dirp->name == NULL && dirp != dirs)
485 if (stat(filename, &stbuf) < 0)
486 return (errno == ENOENT ? ENOTFOUND : EACCESS);
487 if ((stbuf.st_mode & S_IFMT) != S_IFREG)
490 if ((stbuf.st_mode & S_IROTH) == 0)
493 if ((stbuf.st_mode & S_IWOTH) == 0)
500 * Relative file name: search the approved locations for it.
501 * Don't allow write requests that avoid directory
505 if (!strncmp(filename, "../", 3))
509 * If the file exists in one of the directories and isn't
510 * readable, continue looking. However, change the error code
511 * to give an indication that the file exists.
514 for (dirp = dirs; dirp->name != NULL; dirp++) {
515 snprintf(pathname, sizeof(pathname), "%s/%s",
516 dirp->name, filename);
517 if (stat(pathname, &stbuf) == 0 &&
518 (stbuf.st_mode & S_IFMT) == S_IFREG) {
519 if ((stbuf.st_mode & S_IROTH) != 0) {
525 if (dirp->name == NULL)
527 *filep = filename = pathname;
529 if (options[OPT_TSIZE].o_request) {
531 options[OPT_TSIZE].o_reply = stbuf.st_size;
533 /* XXX Allows writes of all sizes. */
534 options[OPT_TSIZE].o_reply =
535 atoi(options[OPT_TSIZE].o_request);
537 fd = open(filename, mode == RRQ ? O_RDONLY : O_WRONLY|O_TRUNC);
539 return (errno + 100);
540 file = fdopen(fd, (mode == RRQ)? "r":"w");
553 if (++timeouts > MAX_TIMEOUTS)
555 longjmp(timeoutbuf, 1);
559 * Send the requested file.
565 struct tftphdr *dp, *r_init();
566 register struct tftphdr *ap; /* ack packet */
567 register int size, n;
568 volatile unsigned short block;
570 signal(SIGALRM, timer);
572 ap = (struct tftphdr *)ackbuf;
575 size = readit(file, &dp, pf->f_convert);
580 dp->th_opcode = htons((u_short)DATA);
581 dp->th_block = htons((u_short)block);
583 (void)setjmp(timeoutbuf);
586 if (send(peer, dp, size + 4, 0) != size + 4) {
587 syslog(LOG_ERR, "write: %m");
590 read_ahead(file, pf->f_convert);
592 alarm(rexmtval); /* read the ack */
593 n = recv(peer, ackbuf, sizeof (ackbuf), 0);
596 syslog(LOG_ERR, "read: %m");
599 ap->th_opcode = ntohs((u_short)ap->th_opcode);
600 ap->th_block = ntohs((u_short)ap->th_block);
602 if (ap->th_opcode == ERROR)
605 if (ap->th_opcode == ACK) {
606 if (ap->th_block == block)
608 /* Re-synchronize with the other side */
609 (void) synchnet(peer);
610 if (ap->th_block == (block -1))
616 } while (size == SEGSIZE);
635 struct tftphdr *dp, *w_init();
636 register struct tftphdr *ap; /* ack buffer */
637 register int n, size;
638 volatile unsigned short block;
640 signal(SIGALRM, timer);
642 ap = (struct tftphdr *)ackbuf;
646 ap->th_opcode = htons((u_short)ACK);
647 ap->th_block = htons((u_short)block);
649 (void) setjmp(timeoutbuf);
651 if (send(peer, ackbuf, 4, 0) != 4) {
652 syslog(LOG_ERR, "write: %m");
655 write_behind(file, pf->f_convert);
658 n = recv(peer, dp, PKTSIZE, 0);
660 if (n < 0) { /* really? */
661 syslog(LOG_ERR, "read: %m");
664 dp->th_opcode = ntohs((u_short)dp->th_opcode);
665 dp->th_block = ntohs((u_short)dp->th_block);
666 if (dp->th_opcode == ERROR)
668 if (dp->th_opcode == DATA) {
669 if (dp->th_block == block) {
672 /* Re-synchronize with the other side */
673 (void) synchnet(peer);
674 if (dp->th_block == (block-1))
675 goto send_ack; /* rexmit */
678 /* size = write(file, dp->th_data, n - 4); */
679 size = writeit(file, &dp, n - 4, pf->f_convert);
680 if (size != (n-4)) { /* ahem */
681 if (size < 0) nak(errno + 100);
685 } while (size == SEGSIZE);
686 write_behind(file, pf->f_convert);
687 (void) fclose(file); /* close data file */
689 ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */
690 ap->th_block = htons((u_short)(block));
691 (void) send(peer, ackbuf, 4, 0);
693 signal(SIGALRM, justquit); /* just quit on timeout */
695 n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
697 if (n >= 4 && /* if read some data */
698 dp->th_opcode == DATA && /* and got a data block */
699 block == dp->th_block) { /* then my last ack was lost */
700 (void) send(peer, ackbuf, 4, 0); /* resend final ack */
710 { EUNDEF, "Undefined error code" },
711 { ENOTFOUND, "File not found" },
712 { EACCESS, "Access violation" },
713 { ENOSPACE, "Disk full or allocation exceeded" },
714 { EBADOP, "Illegal TFTP operation" },
715 { EBADID, "Unknown transfer ID" },
716 { EEXISTS, "File already exists" },
717 { ENOUSER, "No such user" },
718 { EOPTNEG, "Option negotiation" },
727 register struct errmsg *pe;
730 for (pe = errmsgs; pe->e_code >= 0; pe++)
731 if (pe->e_code == error)
733 snprintf(buf, sizeof(buf), "error %d", error);
738 * Send a nak packet (error message).
739 * Error code passed in is one of the
740 * standard TFTP codes, or a UNIX errno
747 register struct tftphdr *tp;
749 register struct errmsg *pe;
751 tp = (struct tftphdr *)buf;
752 tp->th_opcode = htons((u_short)ERROR);
753 tp->th_code = htons((u_short)error);
754 for (pe = errmsgs; pe->e_code >= 0; pe++)
755 if (pe->e_code == error)
757 if (pe->e_code < 0) {
758 pe->e_msg = strerror(error - 100);
759 tp->th_code = EUNDEF; /* set 'undef' errorcode */
761 strcpy(tp->th_msg, pe->e_msg);
762 length = strlen(pe->e_msg);
763 tp->th_msg[length] = '\0';
765 if (send(peer, buf, length, 0) != length)
766 syslog(LOG_ERR, "nak: %m");
770 * Send an oack packet (option acknowledgement).
775 struct tftphdr *tp, *ap;
779 tp = (struct tftphdr *)buf;
781 size = sizeof(buf) - 2;
782 tp->th_opcode = htons((u_short)OACK);
783 for (i = 0; options[i].o_type != NULL; i++) {
784 if (options[i].o_request) {
785 n = snprintf(bp, size, "%s%c%d", options[i].o_type,
786 0, options[i].o_reply);
790 syslog(LOG_ERR, "oack: buffer overflow");
796 ap = (struct tftphdr *)ackbuf;
797 signal(SIGALRM, timer);
800 (void)setjmp(timeoutbuf);
801 if (send(peer, buf, size, 0) != size) {
802 syslog(LOG_INFO, "oack: %m");
808 n = recv(peer, ackbuf, sizeof (ackbuf), 0);
811 syslog(LOG_ERR, "recv: %m");
814 ap->th_opcode = ntohs((u_short)ap->th_opcode);
815 ap->th_block = ntohs((u_short)ap->th_block);
816 if (ap->th_opcode == ERROR)
818 if (ap->th_opcode == ACK && ap->th_block == 0)