1 /* dnsmasq is Copyright (c) 2000-2011 Simon Kelley
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License as published by
5 the Free Software Foundation; version 2 dated June, 1991, or
6 (at your option) version 3 dated 29 June, 2007.
8 This program is distributed in the hope that it will be useful,
9 but WITHOUT ANY WARRANTY; without even the implied warranty of
10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 GNU General Public License for more details.
13 You should have received a copy of the GNU General Public License
14 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 static struct tftp_file *check_tftp_fileperm(ssize_t *len, char *prefix, int special);
22 static void free_transfer(struct tftp_transfer *transfer);
23 static ssize_t tftp_err(int err, char *packet, char *mess, char *file);
24 static ssize_t tftp_err_oops(char *packet, char *file);
25 static ssize_t get_block(char *packet, struct tftp_transfer *transfer);
26 static char *next(char **p, char *end);
41 void tftp_request(struct listener *listen, time_t now)
44 char *packet = daemon->packet;
45 char *filename, *mode, *p, *end, *opt;
46 union mysockaddr addr, peer;
50 int is_err = 1, if_index = 0, mtu = 0, special = 0;
54 struct tftp_transfer *transfer;
55 int port = daemon->start_tftp_port; /* may be zero to use ephemeral port */
56 #if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
57 int mtuflag = IP_PMTUDISC_DONT;
59 char namebuff[IF_NAMESIZE];
60 char pretty_addr[ADDRSTRLEN];
62 char *prefix = daemon->tftp_prefix;
63 struct tftp_prefix *pref;
64 struct interface_list *ir;
67 struct cmsghdr align; /* this ensures alignment */
69 char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
71 #if defined(HAVE_LINUX_NETWORK)
72 char control[CMSG_SPACE(sizeof(struct in_pktinfo))];
73 #elif defined(HAVE_SOLARIS_NETWORK)
74 char control[CMSG_SPACE(sizeof(unsigned int))];
75 #elif defined(IP_RECVDSTADDR) && defined(IP_RECVIF)
76 char control[CMSG_SPACE(sizeof(struct sockaddr_dl))];
80 msg.msg_controllen = sizeof(control_u);
81 msg.msg_control = control_u.control;
84 msg.msg_namelen = sizeof(peer);
88 iov.iov_base = packet;
89 iov.iov_len = daemon->packet_buff_sz;
91 /* we overwrote the buffer... */
92 daemon->srv_save = NULL;
94 if ((len = recvmsg(listen->tftpfd, &msg, 0)) < 2)
97 if (option_bool(OPT_NOWILD))
99 addr = listen->iface->addr;
100 mtu = listen->iface->mtu;
101 name = listen->iface->name;
105 struct cmsghdr *cmptr;
107 struct interface_list *ir;
109 if (msg.msg_controllen < sizeof(struct cmsghdr))
112 addr.sa.sa_family = listen->family;
114 #if defined(HAVE_LINUX_NETWORK)
115 if (listen->family == AF_INET)
116 for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
117 if (cmptr->cmsg_level == SOL_IP && cmptr->cmsg_type == IP_PKTINFO)
121 struct in_pktinfo *p;
123 p.c = CMSG_DATA(cmptr);
124 addr.in.sin_addr = p.p->ipi_spec_dst;
125 if_index = p.p->ipi_ifindex;
128 #elif defined(HAVE_SOLARIS_NETWORK)
129 if (listen->family == AF_INET)
130 for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
137 p.c = CMSG_DATA(cmptr);
138 if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVDSTADDR)
139 addr.in.sin_addr = *(p.a);
140 else if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVIF)
144 #elif defined(IP_RECVDSTADDR) && defined(IP_RECVIF)
145 if (listen->family == AF_INET)
146 for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
151 struct sockaddr_dl *s;
153 p.c = CMSG_DATA(cmptr);
154 if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVDSTADDR)
155 addr.in.sin_addr = *(p.a);
156 else if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVIF)
157 if_index = p.s->sdl_index;
163 if (listen->family == AF_INET6)
165 for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
166 if (cmptr->cmsg_level == IPV6_LEVEL && cmptr->cmsg_type == daemon->v6pktinfo)
170 struct in6_pktinfo *p;
172 p.c = CMSG_DATA(cmptr);
174 addr.in6.sin6_addr = p.p->ipi6_addr;
175 if_index = p.p->ipi6_ifindex;
180 if (!indextoname(listen->tftpfd, if_index, namebuff))
186 if (listen->family == AF_INET6)
187 check = iface_check(AF_INET6, (struct all_addr *)&addr.in6.sin6_addr, name, &if_index);
190 check = iface_check(AF_INET, (struct all_addr *)&addr.in.sin_addr, name, &if_index);
192 /* wierd TFTP service override */
193 for (ir = daemon->tftp_interfaces; ir; ir = ir->next)
194 if (strcmp(ir->interface, name) == 0)
199 if (!daemon->tftp_unlimited || !check)
203 /* allowed interfaces are the same as for DHCP */
204 for (tmp = daemon->dhcp_except; tmp; tmp = tmp->next)
205 if (tmp->name && (strcmp(tmp->name, name) == 0))
210 strncpy(ifr.ifr_name, name, IF_NAMESIZE);
211 if (ioctl(listen->tftpfd, SIOCGIFMTU, &ifr) != -1)
215 /* check for per-interface prefix */
216 for (pref = daemon->if_prefix; pref; pref = pref->next)
217 if (strcmp(pref->interface, name) == 0)
218 prefix = pref->prefix;
220 /* wierd TFTP interfaces disable special options. */
221 for (ir = daemon->tftp_interfaces; ir; ir = ir->next)
222 if (strcmp(ir->interface, name) == 0)
225 #ifdef HAVE_SOCKADDR_SA_LEN
226 addr.sa.sa_len = sa_len(&addr);
229 if (listen->family == AF_INET)
230 addr.in.sin_port = htons(port);
234 addr.in6.sin6_port = htons(port);
235 addr.in6.sin6_flowinfo = 0;
239 if (!(transfer = whine_malloc(sizeof(struct tftp_transfer))))
242 if ((transfer->sockfd = socket(listen->family, SOCK_DGRAM, 0)) == -1)
248 transfer->peer = peer;
249 transfer->timeout = now + 2;
250 transfer->backoff = 1;
252 transfer->blocksize = 512;
253 transfer->offset = 0;
254 transfer->file = NULL;
255 transfer->opt_blocksize = transfer->opt_transize = 0;
256 transfer->netascii = transfer->carrylf = 0;
258 prettyprint_addr(&peer, pretty_addr);
260 /* if we have a nailed-down range, iterate until we find a free one. */
263 if (bind(transfer->sockfd, &addr.sa, sizeof(addr)) == -1 ||
264 #if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
265 setsockopt(transfer->sockfd, SOL_IP, IP_MTU_DISCOVER, &mtuflag, sizeof(mtuflag)) == -1 ||
267 !fix_fd(transfer->sockfd))
269 if (errno == EADDRINUSE && daemon->start_tftp_port != 0)
271 if (++port <= daemon->end_tftp_port)
273 if (listen->family == AF_INET)
274 addr.in.sin_port = htons(port);
277 addr.in6.sin6_port = htons(port);
281 my_syslog(MS_TFTP | LOG_ERR, _("unable to get free port for TFTP"));
283 free_transfer(transfer);
292 if (ntohs(*((unsigned short *)packet)) != OP_RRQ ||
293 !(filename = next(&p, end)) ||
294 !(mode = next(&p, end)) ||
295 (strcasecmp(mode, "octet") != 0 && strcasecmp(mode, "netascii") != 0))
296 len = tftp_err(ERR_ILL, packet, _("unsupported request from %s"), pretty_addr);
299 if (strcasecmp(mode, "netascii") == 0)
300 transfer->netascii = 1;
302 while ((opt = next(&p, end)))
304 if (strcasecmp(opt, "blksize") == 0)
306 if ((opt = next(&p, end)) &&
307 (special || !option_bool(OPT_TFTP_NOBLOCK)))
309 transfer->blocksize = atoi(opt);
310 if (transfer->blocksize < 1)
311 transfer->blocksize = 1;
312 if (transfer->blocksize > (unsigned)daemon->packet_buff_sz - 4)
313 transfer->blocksize = (unsigned)daemon->packet_buff_sz - 4;
314 /* 32 bytes for IP, UDP and TFTP headers */
315 if (mtu != 0 && transfer->blocksize > (unsigned)mtu - 32)
316 transfer->blocksize = (unsigned)mtu - 32;
317 transfer->opt_blocksize = 1;
321 else if (strcasecmp(opt, "tsize") == 0 && next(&p, end) && !transfer->netascii)
323 transfer->opt_transize = 1;
328 /* cope with backslashes from windows boxen. */
329 while ((p = strchr(filename, '\\')))
332 strcpy(daemon->namebuff, "/");
335 if (prefix[0] == '/')
336 daemon->namebuff[0] = 0;
337 strncat(daemon->namebuff, prefix, (MAXDNAME-1) - strlen(daemon->namebuff));
338 if (prefix[strlen(prefix)-1] != '/')
339 strncat(daemon->namebuff, "/", (MAXDNAME-1) - strlen(daemon->namebuff));
341 if (!special && option_bool(OPT_TFTP_APREF))
343 size_t oldlen = strlen(daemon->namebuff);
346 strncat(daemon->namebuff, pretty_addr, (MAXDNAME-1) - strlen(daemon->namebuff));
347 strncat(daemon->namebuff, "/", (MAXDNAME-1) - strlen(daemon->namebuff));
349 /* remove unique-directory if it doesn't exist */
350 if (stat(daemon->namebuff, &statbuf) == -1 || !S_ISDIR(statbuf.st_mode))
351 daemon->namebuff[oldlen] = 0;
354 /* Absolute pathnames OK if they match prefix */
355 if (filename[0] == '/')
357 if (strstr(filename, daemon->namebuff) == filename)
358 daemon->namebuff[0] = 0;
363 else if (filename[0] == '/')
364 daemon->namebuff[0] = 0;
365 strncat(daemon->namebuff, filename, (MAXDNAME-1) - strlen(daemon->namebuff));
367 /* check permissions and open file */
368 if ((transfer->file = check_tftp_fileperm(&len, prefix, special)))
370 if ((len = get_block(packet, transfer)) == -1)
371 len = tftp_err_oops(packet, daemon->namebuff);
377 while (sendto(transfer->sockfd, packet, len, 0,
378 (struct sockaddr *)&peer, sizeof(peer)) == -1 && errno == EINTR);
381 free_transfer(transfer);
384 transfer->next = daemon->tftp_trans;
385 daemon->tftp_trans = transfer;
389 static struct tftp_file *check_tftp_fileperm(ssize_t *len, char *prefix, int special)
391 char *packet = daemon->packet, *namebuff = daemon->namebuff;
392 struct tftp_file *file;
393 struct tftp_transfer *t;
394 uid_t uid = geteuid();
398 /* trick to ban moving out of the subtree */
399 if (prefix && strstr(namebuff, "/../"))
402 if ((fd = open(namebuff, O_RDONLY)) == -1)
406 *len = tftp_err(ERR_FNF, packet, _("file %s not found"), namebuff);
409 else if (errno == EACCES)
415 /* stat the file descriptor to avoid stat->open races */
416 if (fstat(fd, &statbuf) == -1)
419 /* running as root, must be world-readable */
422 if (!(statbuf.st_mode & S_IROTH))
425 /* in secure mode, must be owned by user running dnsmasq */
426 else if (!special && option_bool(OPT_TFTP_SECURE) && uid != statbuf.st_uid)
429 /* If we're doing many tranfers from the same file, only
430 open it once this saves lots of file descriptors
431 when mass-booting a big cluster, for instance.
432 Be conservative and only share when inode and name match
433 this keeps error messages sane. */
434 for (t = daemon->tftp_trans; t; t = t->next)
435 if (t->file->dev == statbuf.st_dev &&
436 t->file->inode == statbuf.st_ino &&
437 strcmp(t->file->filename, namebuff) == 0)
444 if (!(file = whine_malloc(sizeof(struct tftp_file) + strlen(namebuff) + 1)))
451 file->size = statbuf.st_size;
452 file->dev = statbuf.st_dev;
453 file->inode = statbuf.st_ino;
455 strcpy(file->filename, namebuff);
460 *len = tftp_err(ERR_PERM, packet, _("cannot access %s: %s"), namebuff);
466 *len = tftp_err_oops(packet, namebuff);
472 void check_tftp_listeners(fd_set *rset, time_t now)
474 struct tftp_transfer *transfer, *tmp, **up;
476 char pretty_addr[ADDRSTRLEN];
479 unsigned short op, block;
480 } *mess = (struct ack *)daemon->packet;
482 /* Check for activity on any existing transfers */
483 for (transfer = daemon->tftp_trans, up = &daemon->tftp_trans; transfer; transfer = tmp)
485 tmp = transfer->next;
487 if (FD_ISSET(transfer->sockfd, rset))
489 /* we overwrote the buffer... */
490 daemon->srv_save = NULL;
492 prettyprint_addr(&transfer->peer, pretty_addr);
494 if ((len = recv(transfer->sockfd, daemon->packet, daemon->packet_buff_sz, 0)) >= (ssize_t)sizeof(struct ack))
496 if (ntohs(mess->op) == OP_ACK && ntohs(mess->block) == (unsigned short)transfer->block)
498 /* Got ack, ensure we take the (re)transmit path */
499 transfer->timeout = now;
500 transfer->backoff = 0;
501 if (transfer->block++ != 0)
502 transfer->offset += transfer->blocksize - transfer->expansion;
504 else if (ntohs(mess->op) == OP_ERR)
506 char *p = daemon->packet + sizeof(struct ack);
507 char *end = daemon->packet + len;
508 char *err = next(&p, end);
510 /* Sanitise error message */
515 unsigned char *q, *r;
516 for (q = r = (unsigned char *)err; *r; r++)
522 my_syslog(MS_TFTP | LOG_ERR, _("error %d %s received from %s"),
523 (int)ntohs(mess->block), err,
526 /* Got err, ensure we take abort */
527 transfer->timeout = now;
528 transfer->backoff = 100;
533 if (difftime(now, transfer->timeout) >= 0.0)
537 /* timeout, retransmit */
538 transfer->timeout += 1 + (1<<transfer->backoff);
540 /* we overwrote the buffer... */
541 daemon->srv_save = NULL;
543 if ((len = get_block(daemon->packet, transfer)) == -1)
545 len = tftp_err_oops(daemon->packet, transfer->file->filename);
548 else if (++transfer->backoff > 5)
550 /* don't complain about timeout when we're awaiting the last
551 ACK, some clients never send it */
554 my_syslog(MS_TFTP | LOG_ERR, _("failed sending %s to %s"),
555 transfer->file->filename, pretty_addr);
562 while(sendto(transfer->sockfd, daemon->packet, len, 0,
563 (struct sockaddr *)&transfer->peer, sizeof(transfer->peer)) == -1 && errno == EINTR);
565 if (endcon || len == 0)
568 my_syslog(MS_TFTP | LOG_INFO, _("sent %s to %s"), transfer->file->filename, pretty_addr);
571 free_transfer(transfer);
576 up = &transfer->next;
580 static void free_transfer(struct tftp_transfer *transfer)
582 close(transfer->sockfd);
583 if (transfer->file && (--transfer->file->refcount) == 0)
585 close(transfer->file->fd);
586 free(transfer->file);
591 static char *next(char **p, char *end)
598 (len = strlen(ret)) == 0)
605 static ssize_t tftp_err(int err, char *packet, char *message, char *file)
608 unsigned short op, err;
610 } *mess = (struct errmess *)packet;
612 char *errstr = strerror(errno);
614 mess->op = htons(OP_ERR);
615 mess->err = htons(err);
616 ret += (snprintf(mess->message, 500, message, file, errstr) + 1);
617 my_syslog(MS_TFTP | LOG_ERR, "%s", mess->message);
622 static ssize_t tftp_err_oops(char *packet, char *file)
624 return tftp_err(ERR_NOTDEF, packet, _("cannot read %s: %s"), file);
627 /* return -1 for error, zero for done. */
628 static ssize_t get_block(char *packet, struct tftp_transfer *transfer)
630 if (transfer->block == 0)
637 } *mess = (struct oackmess *)packet;
640 mess->op = htons(OP_OACK);
641 if (transfer->opt_blocksize)
643 p += (sprintf(p, "blksize") + 1);
644 p += (sprintf(p, "%d", transfer->blocksize) + 1);
646 if (transfer->opt_transize)
648 p += (sprintf(p,"tsize") + 1);
649 p += (sprintf(p, "%u", (unsigned int)transfer->file->size) + 1);
656 /* send data packet */
658 unsigned short op, block;
659 unsigned char data[];
660 } *mess = (struct datamess *)packet;
662 size_t size = transfer->file->size - transfer->offset;
664 if (transfer->offset > transfer->file->size)
665 return 0; /* finished */
667 if (size > transfer->blocksize)
668 size = transfer->blocksize;
670 mess->op = htons(OP_DATA);
671 mess->block = htons((unsigned short)(transfer->block));
673 if (lseek(transfer->file->fd, transfer->offset, SEEK_SET) == (off_t)-1 ||
674 !read_write(transfer->file->fd, mess->data, size, 1))
677 transfer->expansion = 0;
679 /* Map '\n' to CR-LF in netascii mode */
680 if (transfer->netascii)
685 for (i = 0, newcarrylf = 0; i < size; i++)
686 if (mess->data[i] == '\n' && ( i != 0 || !transfer->carrylf))
688 if (size == transfer->blocksize)
690 transfer->expansion++;
692 newcarrylf = 1; /* don't expand LF again if it moves to the next block */
695 size++; /* room in this block */
697 /* make space and insert CR */
698 memmove(&mess->data[i+1], &mess->data[i], size - (i + 1));
699 mess->data[i] = '\r';
703 transfer->carrylf = newcarrylf;