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freebsd-skq/libexec/tftpd/tftpd.c
ume c9e55ed3c8 Correct indent.
2002-04-26 12:27:55 +00:00

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/*
* Copyright (c) 1983, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1983, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)tftpd.c 8.1 (Berkeley) 6/4/93";
#endif
static const char rcsid[] =
"$FreeBSD$";
#endif /* not lint */
/*
* Trivial file transfer protocol server.
*
* This version includes many modifications by Jim Guyton
* <guyton@rand-unix>.
*/
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/tftp.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <netdb.h>
#include <pwd.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "tftpsubs.h"
#define TIMEOUT 5
#define MAX_TIMEOUTS 5
int peer;
int rexmtval = TIMEOUT;
int max_rexmtval = 2*TIMEOUT;
#define PKTSIZE SEGSIZE+4
char buf[PKTSIZE];
char ackbuf[PKTSIZE];
struct sockaddr_storage from;
int fromlen;
void tftp(struct tftphdr *, int);
static void unmappedaddr(struct sockaddr_in6 *);
/*
* Null-terminated directory prefix list for absolute pathname requests and
* search list for relative pathname requests.
*
* MAXDIRS should be at least as large as the number of arguments that
* inetd allows (currently 20).
*/
#define MAXDIRS 20
static struct dirlist {
char *name;
int len;
} dirs[MAXDIRS+1];
static int suppress_naks;
static int logging;
static int ipchroot;
static char *errtomsg(int);
static void nak(int);
static void oack();
int
main(int argc, char *argv[])
{
struct tftphdr *tp;
int n;
int ch, on;
struct sockaddr_storage me;
int len;
char *chroot_dir = NULL;
struct passwd *nobody;
char *chuser = "nobody";
openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
while ((ch = getopt(argc, argv, "cClns:u:")) != -1) {
switch (ch) {
case 'c':
ipchroot = 1;
break;
case 'C':
ipchroot = 2;
break;
case 'l':
logging = 1;
break;
case 'n':
suppress_naks = 1;
break;
case 's':
chroot_dir = optarg;
break;
case 'u':
chuser = optarg;
break;
default:
syslog(LOG_WARNING, "ignoring unknown option -%c", ch);
}
}
if (optind < argc) {
struct dirlist *dirp;
/* Get list of directory prefixes. Skip relative pathnames. */
for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
optind++) {
if (argv[optind][0] == '/') {
dirp->name = argv[optind];
dirp->len = strlen(dirp->name);
dirp++;
}
}
}
else if (chroot_dir) {
dirs->name = "/";
dirs->len = 1;
}
if (ipchroot && chroot_dir == NULL) {
syslog(LOG_ERR, "-c requires -s");
exit(1);
}
on = 1;
if (ioctl(0, FIONBIO, &on) < 0) {
syslog(LOG_ERR, "ioctl(FIONBIO): %m");
exit(1);
}
fromlen = sizeof (from);
n = recvfrom(0, buf, sizeof (buf), 0,
(struct sockaddr *)&from, &fromlen);
if (n < 0) {
syslog(LOG_ERR, "recvfrom: %m");
exit(1);
}
/*
* Now that we have read the message out of the UDP
* socket, we fork and exit. Thus, inetd will go back
* to listening to the tftp port, and the next request
* to come in will start up a new instance of tftpd.
*
* We do this so that inetd can run tftpd in "wait" mode.
* The problem with tftpd running in "nowait" mode is that
* inetd may get one or more successful "selects" on the
* tftp port before we do our receive, so more than one
* instance of tftpd may be started up. Worse, if tftpd
* break before doing the above "recvfrom", inetd would
* spawn endless instances, clogging the system.
*/
{
int pid;
int i, j;
for (i = 1; i < 20; i++) {
pid = fork();
if (pid < 0) {
sleep(i);
/*
* flush out to most recently sent request.
*
* This may drop some request, but those
* will be resent by the clients when
* they timeout. The positive effect of
* this flush is to (try to) prevent more
* than one tftpd being started up to service
* a single request from a single client.
*/
j = sizeof from;
i = recvfrom(0, buf, sizeof (buf), 0,
(struct sockaddr *)&from, &j);
if (i > 0) {
n = i;
fromlen = j;
}
} else {
break;
}
}
if (pid < 0) {
syslog(LOG_ERR, "fork: %m");
exit(1);
} else if (pid != 0) {
exit(0);
}
}
/*
* Since we exit here, we should do that only after the above
* recvfrom to keep inetd from constantly forking should there
* be a problem. See the above comment about system clogging.
*/
if (chroot_dir) {
if (ipchroot) {
char *tempchroot;
struct stat sb;
int statret;
struct sockaddr_storage ss;
char hbuf[NI_MAXHOST];
memcpy(&ss, &from, from.ss_len);
unmappedaddr((struct sockaddr_in6 *)&ss);
getnameinfo((struct sockaddr *)&ss, ss.ss_len,
hbuf, sizeof(hbuf), NULL, 0,
NI_NUMERICHOST | NI_WITHSCOPEID);
asprintf(&tempchroot, "%s/%s", chroot_dir, hbuf);
statret = stat(tempchroot, &sb);
if ((sb.st_mode & S_IFDIR) &&
(statret == 0 || (statret == -1 && ipchroot == 1)))
chroot_dir = tempchroot;
}
/* Must get this before chroot because /etc might go away */
if ((nobody = getpwnam(chuser)) == NULL) {
syslog(LOG_ERR, "%s: no such user", chuser);
exit(1);
}
if (chroot(chroot_dir)) {
syslog(LOG_ERR, "chroot: %s: %m", chroot_dir);
exit(1);
}
chdir( "/" );
setuid(nobody->pw_uid);
setgroups(1, &nobody->pw_gid);
}
len = sizeof(me);
if (getsockname(0, (struct sockaddr *)&me, &len) == 0) {
switch (me.ss_family) {
case AF_INET:
((struct sockaddr_in *)&me)->sin_port = 0;
break;
case AF_INET6:
((struct sockaddr_in6 *)&me)->sin6_port = 0;
break;
default:
/* unsupported */
break;
}
} else {
memset(&me, 0, sizeof(me));
me.ss_family = from.ss_family;
me.ss_len = from.ss_len;
}
alarm(0);
close(0);
close(1);
peer = socket(from.ss_family, SOCK_DGRAM, 0);
if (peer < 0) {
syslog(LOG_ERR, "socket: %m");
exit(1);
}
if (bind(peer, (struct sockaddr *)&me, me.ss_len) < 0) {
syslog(LOG_ERR, "bind: %m");
exit(1);
}
if (connect(peer, (struct sockaddr *)&from, from.ss_len) < 0) {
syslog(LOG_ERR, "connect: %m");
exit(1);
}
tp = (struct tftphdr *)buf;
tp->th_opcode = ntohs(tp->th_opcode);
if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
tftp(tp, n);
exit(1);
}
struct formats;
int validate_access(char **, int);
void xmitfile(struct formats *);
void recvfile(struct formats *);
struct formats {
char *f_mode;
int (*f_validate)(char **, int);
void (*f_send)(struct formats *);
void (*f_recv)(struct formats *);
int f_convert;
} formats[] = {
{ "netascii", validate_access, xmitfile, recvfile, 1 },
{ "octet", validate_access, xmitfile, recvfile, 0 },
#ifdef notdef
{ "mail", validate_user, sendmail, recvmail, 1 },
#endif
{ 0 }
};
struct options {
char *o_type;
char *o_request;
int o_reply; /* turn into union if need be */
} options[] = {
{ "tsize" }, /* OPT_TSIZE */
{ "timeout" }, /* OPT_TIMEOUT */
{ NULL }
};
enum opt_enum {
OPT_TSIZE = 0,
OPT_TIMEOUT,
};
/*
* Handle initial connection protocol.
*/
void
tftp(struct tftphdr *tp, int size)
{
char *cp;
int i, first = 1, has_options = 0, ecode;
struct formats *pf;
char *filename, *mode, *option, *ccp;
filename = cp = tp->th_stuff;
again:
while (cp < buf + size) {
if (*cp == '\0')
break;
cp++;
}
if (*cp != '\0') {
nak(EBADOP);
exit(1);
}
if (first) {
mode = ++cp;
first = 0;
goto again;
}
for (cp = mode; *cp; cp++)
if (isupper(*cp))
*cp = tolower(*cp);
for (pf = formats; pf->f_mode; pf++)
if (strcmp(pf->f_mode, mode) == 0)
break;
if (pf->f_mode == 0) {
nak(EBADOP);
exit(1);
}
while (++cp < buf + size) {
for (i = 2, ccp = cp; i > 0; ccp++) {
if (ccp >= buf + size) {
/*
* Don't reject the request, just stop trying
* to parse the option and get on with it.
* Some Apple OpenFirmware versions have
* trailing garbage on the end of otherwise
* valid requests.
*/
goto option_fail;
} else if (*ccp == '\0')
i--;
}
for (option = cp; *cp; cp++)
if (isupper(*cp))
*cp = tolower(*cp);
for (i = 0; options[i].o_type != NULL; i++)
if (strcmp(option, options[i].o_type) == 0) {
options[i].o_request = ++cp;
has_options = 1;
}
cp = ccp-1;
}
option_fail:
if (options[OPT_TIMEOUT].o_request) {
int to = atoi(options[OPT_TIMEOUT].o_request);
if (to < 1 || to > 255) {
nak(EBADOP);
exit(1);
}
else if (to <= max_rexmtval)
options[OPT_TIMEOUT].o_reply = rexmtval = to;
else
options[OPT_TIMEOUT].o_request = NULL;
}
ecode = (*pf->f_validate)(&filename, tp->th_opcode);
if (has_options)
oack();
if (logging) {
char hbuf[NI_MAXHOST];
getnameinfo((struct sockaddr *)&from, from.ss_len,
hbuf, sizeof(hbuf), NULL, 0,
NI_WITHSCOPEID);
syslog(LOG_INFO, "%s: %s request for %s: %s", hbuf,
tp->th_opcode == WRQ ? "write" : "read",
filename, errtomsg(ecode));
}
if (ecode) {
/*
* Avoid storms of naks to a RRQ broadcast for a relative
* bootfile pathname from a diskless Sun.
*/
if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
exit(0);
nak(ecode);
exit(1);
}
if (tp->th_opcode == WRQ)
(*pf->f_recv)(pf);
else
(*pf->f_send)(pf);
exit(0);
}
FILE *file;
/*
* Validate file access. Since we
* have no uid or gid, for now require
* file to exist and be publicly
* readable/writable.
* If we were invoked with arguments
* from inetd then the file must also be
* in one of the given directory prefixes.
* Note also, full path name must be
* given as we have no login directory.
*/
int
validate_access(char **filep, int mode)
{
struct stat stbuf;
int fd;
struct dirlist *dirp;
static char pathname[MAXPATHLEN];
char *filename = *filep;
/*
* Prevent tricksters from getting around the directory restrictions
*/
if (strstr(filename, "/../"))
return (EACCESS);
if (*filename == '/') {
/*
* Allow the request if it's in one of the approved locations.
* Special case: check the null prefix ("/") by looking
* for length = 1 and relying on the arg. processing that
* it's a /.
*/
for (dirp = dirs; dirp->name != NULL; dirp++) {
if (dirp->len == 1 ||
(!strncmp(filename, dirp->name, dirp->len) &&
filename[dirp->len] == '/'))
break;
}
/* If directory list is empty, allow access to any file */
if (dirp->name == NULL && dirp != dirs)
return (EACCESS);
if (stat(filename, &stbuf) < 0)
return (errno == ENOENT ? ENOTFOUND : EACCESS);
if ((stbuf.st_mode & S_IFMT) != S_IFREG)
return (ENOTFOUND);
if (mode == RRQ) {
if ((stbuf.st_mode & S_IROTH) == 0)
return (EACCESS);
} else {
if ((stbuf.st_mode & S_IWOTH) == 0)
return (EACCESS);
}
} else {
int err;
/*
* Relative file name: search the approved locations for it.
* Don't allow write requests that avoid directory
* restrictions.
*/
if (!strncmp(filename, "../", 3))
return (EACCESS);
/*
* If the file exists in one of the directories and isn't
* readable, continue looking. However, change the error code
* to give an indication that the file exists.
*/
err = ENOTFOUND;
for (dirp = dirs; dirp->name != NULL; dirp++) {
snprintf(pathname, sizeof(pathname), "%s/%s",
dirp->name, filename);
if (stat(pathname, &stbuf) == 0 &&
(stbuf.st_mode & S_IFMT) == S_IFREG) {
if ((stbuf.st_mode & S_IROTH) != 0) {
break;
}
err = EACCESS;
}
}
if (dirp->name == NULL)
return (err);
*filep = filename = pathname;
}
if (options[OPT_TSIZE].o_request) {
if (mode == RRQ)
options[OPT_TSIZE].o_reply = stbuf.st_size;
else
/* XXX Allows writes of all sizes. */
options[OPT_TSIZE].o_reply =
atoi(options[OPT_TSIZE].o_request);
}
fd = open(filename, mode == RRQ ? O_RDONLY : O_WRONLY|O_TRUNC);
if (fd < 0)
return (errno + 100);
file = fdopen(fd, (mode == RRQ)? "r":"w");
if (file == NULL) {
return errno+100;
}
return (0);
}
int timeouts;
jmp_buf timeoutbuf;
void
timer(int sig __unused)
{
if (++timeouts > MAX_TIMEOUTS)
exit(1);
longjmp(timeoutbuf, 1);
}
/*
* Send the requested file.
*/
void
xmitfile(struct formats *pf)
{
struct tftphdr *dp, *r_init();
struct tftphdr *ap; /* ack packet */
int size, n;
volatile unsigned short block;
signal(SIGALRM, timer);
dp = r_init();
ap = (struct tftphdr *)ackbuf;
block = 1;
do {
size = readit(file, &dp, pf->f_convert);
if (size < 0) {
nak(errno + 100);
goto abort;
}
dp->th_opcode = htons((u_short)DATA);
dp->th_block = htons((u_short)block);
timeouts = 0;
(void)setjmp(timeoutbuf);
send_data:
{
int i, t = 1;
for (i = 0; ; i++){
if (send(peer, dp, size + 4, 0) != size + 4) {
sleep(t);
t = (t < 32) ? t<< 1 : t;
if (i >= 12) {
syslog(LOG_ERR, "write: %m");
goto abort;
}
}
break;
}
}
read_ahead(file, pf->f_convert);
for ( ; ; ) {
alarm(rexmtval); /* read the ack */
n = recv(peer, ackbuf, sizeof (ackbuf), 0);
alarm(0);
if (n < 0) {
syslog(LOG_ERR, "read: %m");
goto abort;
}
ap->th_opcode = ntohs((u_short)ap->th_opcode);
ap->th_block = ntohs((u_short)ap->th_block);
if (ap->th_opcode == ERROR)
goto abort;
if (ap->th_opcode == ACK) {
if (ap->th_block == block)
break;
/* Re-synchronize with the other side */
(void) synchnet(peer);
if (ap->th_block == (block -1))
goto send_data;
}
}
block++;
} while (size == SEGSIZE);
abort:
(void) fclose(file);
}
void
justquit(int sig __unused)
{
exit(0);
}
/*
* Receive a file.
*/
void
recvfile(struct formats *pf)
{
struct tftphdr *dp, *w_init();
struct tftphdr *ap; /* ack buffer */
int n, size;
volatile unsigned short block;
signal(SIGALRM, timer);
dp = w_init();
ap = (struct tftphdr *)ackbuf;
block = 0;
do {
timeouts = 0;
ap->th_opcode = htons((u_short)ACK);
ap->th_block = htons((u_short)block);
block++;
(void) setjmp(timeoutbuf);
send_ack:
if (send(peer, ackbuf, 4, 0) != 4) {
syslog(LOG_ERR, "write: %m");
goto abort;
}
write_behind(file, pf->f_convert);
for ( ; ; ) {
alarm(rexmtval);
n = recv(peer, dp, PKTSIZE, 0);
alarm(0);
if (n < 0) { /* really? */
syslog(LOG_ERR, "read: %m");
goto abort;
}
dp->th_opcode = ntohs((u_short)dp->th_opcode);
dp->th_block = ntohs((u_short)dp->th_block);
if (dp->th_opcode == ERROR)
goto abort;
if (dp->th_opcode == DATA) {
if (dp->th_block == block) {
break; /* normal */
}
/* Re-synchronize with the other side */
(void) synchnet(peer);
if (dp->th_block == (block-1))
goto send_ack; /* rexmit */
}
}
/* size = write(file, dp->th_data, n - 4); */
size = writeit(file, &dp, n - 4, pf->f_convert);
if (size != (n-4)) { /* ahem */
if (size < 0) nak(errno + 100);
else nak(ENOSPACE);
goto abort;
}
} while (size == SEGSIZE);
write_behind(file, pf->f_convert);
(void) fclose(file); /* close data file */
ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */
ap->th_block = htons((u_short)(block));
(void) send(peer, ackbuf, 4, 0);
signal(SIGALRM, justquit); /* just quit on timeout */
alarm(rexmtval);
n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
alarm(0);
if (n >= 4 && /* if read some data */
dp->th_opcode == DATA && /* and got a data block */
block == dp->th_block) { /* then my last ack was lost */
(void) send(peer, ackbuf, 4, 0); /* resend final ack */
}
abort:
return;
}
struct errmsg {
int e_code;
char *e_msg;
} errmsgs[] = {
{ EUNDEF, "Undefined error code" },
{ ENOTFOUND, "File not found" },
{ EACCESS, "Access violation" },
{ ENOSPACE, "Disk full or allocation exceeded" },
{ EBADOP, "Illegal TFTP operation" },
{ EBADID, "Unknown transfer ID" },
{ EEXISTS, "File already exists" },
{ ENOUSER, "No such user" },
{ EOPTNEG, "Option negotiation" },
{ -1, 0 }
};
static char *
errtomsg(int error)
{
static char buf[20];
struct errmsg *pe;
if (error == 0)
return "success";
for (pe = errmsgs; pe->e_code >= 0; pe++)
if (pe->e_code == error)
return pe->e_msg;
snprintf(buf, sizeof(buf), "error %d", error);
return buf;
}
/*
* Send a nak packet (error message).
* Error code passed in is one of the
* standard TFTP codes, or a UNIX errno
* offset by 100.
*/
static void
nak(int error)
{
struct tftphdr *tp;
int length;
struct errmsg *pe;
tp = (struct tftphdr *)buf;
tp->th_opcode = htons((u_short)ERROR);
tp->th_code = htons((u_short)error);
for (pe = errmsgs; pe->e_code >= 0; pe++)
if (pe->e_code == error)
break;
if (pe->e_code < 0) {
pe->e_msg = strerror(error - 100);
tp->th_code = EUNDEF; /* set 'undef' errorcode */
}
strcpy(tp->th_msg, pe->e_msg);
length = strlen(pe->e_msg);
tp->th_msg[length] = '\0';
length += 5;
if (send(peer, buf, length, 0) != length)
syslog(LOG_ERR, "nak: %m");
}
/* translate IPv4 mapped IPv6 address to IPv4 address */
static void
unmappedaddr(struct sockaddr_in6 *sin6)
{
struct sockaddr_in *sin4;
u_int32_t addr;
int port;
if (sin6->sin6_family != AF_INET6 ||
!IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
return;
sin4 = (struct sockaddr_in *)sin6;
addr = *(u_int32_t *)&sin6->sin6_addr.s6_addr[12];
port = sin6->sin6_port;
memset(sin4, 0, sizeof(struct sockaddr_in));
sin4->sin_addr.s_addr = addr;
sin4->sin_port = port;
sin4->sin_family = AF_INET;
sin4->sin_len = sizeof(struct sockaddr_in);
}
/*
* Send an oack packet (option acknowledgement).
*/
static void
oack(void)
{
struct tftphdr *tp, *ap;
int size, i, n;
char *bp;
tp = (struct tftphdr *)buf;
bp = buf + 2;
size = sizeof(buf) - 2;
tp->th_opcode = htons((u_short)OACK);
for (i = 0; options[i].o_type != NULL; i++) {
if (options[i].o_request) {
n = snprintf(bp, size, "%s%c%d", options[i].o_type,
0, options[i].o_reply);
bp += n+1;
size -= n+1;
if (size < 0) {
syslog(LOG_ERR, "oack: buffer overflow");
exit(1);
}
}
}
size = bp - buf;
ap = (struct tftphdr *)ackbuf;
signal(SIGALRM, timer);
timeouts = 0;
(void)setjmp(timeoutbuf);
if (send(peer, buf, size, 0) != size) {
syslog(LOG_INFO, "oack: %m");
exit(1);
}
for (;;) {
alarm(rexmtval);
n = recv(peer, ackbuf, sizeof (ackbuf), 0);
alarm(0);
if (n < 0) {
syslog(LOG_ERR, "recv: %m");
exit(1);
}
ap->th_opcode = ntohs((u_short)ap->th_opcode);
ap->th_block = ntohs((u_short)ap->th_block);
if (ap->th_opcode == ERROR)
exit(1);
if (ap->th_opcode == ACK && ap->th_block == 0)
break;
}
}
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