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/*-
* Copyright (c) 1988, 1989, 1992, 1993, 1994
* 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.
*/
/*
* remote shell server:
* [port]\0
* remuser\0
* locuser\0
* command\0
* data
*/
#include "bsd_locl.h"
RCSID("$Id: rshd.c,v 1.51 1997/05/13 09:42:39 bg Exp $");
extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */
extern int __check_rhosts_file;
static int keepalive = 1;
static int log_success; /* If TRUE, log all successful accesses */
static int new_pag = 1; /* Put process in new PAG by default */
static int no_inetd = 0;
static int sent_null;
static void doit (struct sockaddr_in *);
static void error (const char *, ...)
#ifdef __GNUC__
__attribute__ ((format (printf, 1, 2)))
#endif
;
static void usage (void);
#define VERSION_SIZE 9
#define SECURE_MESSAGE "This rsh session is using DES encryption for all transmissions.\r\n"
#define OPTIONS "alnkvxLp:Pi"
AUTH_DAT authbuf;
KTEXT_ST tickbuf;
int doencrypt, use_kerberos, vacuous;
Key_schedule schedule;
int
main(int argc, char *argv[])
{
struct linger linger;
int ch, on = 1, fromlen;
struct sockaddr_in from;
int portnum = 0;
set_progname(argv[0]);
openlog("rshd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
opterr = 0;
while ((ch = getopt(argc, argv, OPTIONS)) != EOF)
switch (ch) {
case 'a':
break;
case 'l':
__check_rhosts_file = 0;
break;
case 'n':
keepalive = 0;
break;
case 'k':
use_kerberos = 1;
break;
case 'v':
vacuous = 1;
break;
case 'x':
doencrypt = 1;
break;
case 'L':
log_success = 1;
break;
case 'p':
portnum = htons(atoi(optarg));
break;
case 'P':
new_pag = 0;
break;
case 'i':
no_inetd = 1;
break;
case '?':
default:
usage();
break;
}
argc -= optind;
argv += optind;
if (use_kerberos && vacuous) {
syslog(LOG_ERR, "only one of -k and -v allowed");
exit(2);
}
if (doencrypt && !use_kerberos) {
syslog(LOG_ERR, "-k is required for -x");
exit(2);
}
if (no_inetd) {
if(portnum == 0)
portnum = get_shell_port (use_kerberos, doencrypt);
mini_inetd (portnum);
}
fromlen = sizeof (from);
if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
syslog(LOG_ERR, "getpeername: %m");
_exit(1);
}
#ifdef HAVE_SETSOCKOPT
#ifdef SO_KEEPALIVE
if (keepalive &&
setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
sizeof(on)) < 0)
syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
#endif
#ifdef SO_LINGER
linger.l_onoff = 1;
linger.l_linger = 60; /* XXX */
if (setsockopt(0, SOL_SOCKET, SO_LINGER, (void *)&linger,
sizeof (linger)) < 0)
syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m");
#endif
#endif /* HAVE_SETSOCKOPT */
doit(&from);
/* NOTREACHED */
return 0;
}
char username[20] = "USER=";
char homedir[64] = "HOME=";
char shell[64] = "SHELL=";
char path[100] = "PATH=";
char *envinit[] =
{homedir, shell, path, username, 0};
static void
xgetstr(char *buf, int cnt, char *err)
{
char c;
do {
if (read(STDIN_FILENO, &c, 1) != 1)
exit(1);
*buf++ = c;
if (--cnt == 0) {
error("%s too long\n", err);
exit(1);
}
} while (c != 0);
}
static void
doit(struct sockaddr_in *fromp)
{
struct passwd *pwd;
u_short port;
fd_set ready, readfrom;
int cc, nfd, pv[2], pid, s;
int one = 1;
const char *errorhost = "";
char *errorstr;
char *cp, sig, buf[BUFSIZ];
char cmdbuf[NCARGS+1], locuser[16], remuser[16];
char remotehost[2 * MaxHostNameLen + 1];
AUTH_DAT *kdata;
KTEXT ticket;
char instance[INST_SZ], version[VERSION_SIZE];
struct sockaddr_in fromaddr;
int rc;
long authopts;
int pv1[2], pv2[2];
fd_set wready, writeto;
fromaddr = *fromp;
signal(SIGINT, SIG_DFL);
signal(SIGQUIT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
#ifdef DEBUG
{ int t = open(_PATH_TTY, 2);
if (t >= 0) {
ioctl(t, TIOCNOTTY, (char *)0);
close(t);
}
}
#endif
fromp->sin_port = ntohs((u_short)fromp->sin_port);
if (fromp->sin_family != AF_INET) {
syslog(LOG_ERR, "malformed \"from\" address (af %d)\n",
fromp->sin_family);
exit(1);
}
if (!use_kerberos) {
ip_options_and_die (0, fromp);
if (fromp->sin_port >= IPPORT_RESERVED ||
fromp->sin_port < IPPORT_RESERVED/2) {
syslog(LOG_NOTICE|LOG_AUTH,
"Connection from %s on illegal port %u",
inet_ntoa(fromp->sin_addr),
fromp->sin_port);
exit(1);
}
}
alarm(60);
port = 0;
for (;;) {
char c;
if ((cc = read(STDIN_FILENO, &c, 1)) != 1) {
if (cc < 0)
syslog(LOG_NOTICE, "read: %m");
shutdown(0, 1+1);
exit(1);
}
if (c== 0)
break;
port = port * 10 + c - '0';
}
alarm(0);
if (port != 0) {
int lport = IPPORT_RESERVED - 1;
s = rresvport(&lport);
if (s < 0) {
syslog(LOG_ERR, "can't get stderr port: %m");
exit(1);
}
if (!use_kerberos)
if (port >= IPPORT_RESERVED) {
syslog(LOG_ERR, "2nd port not reserved\n");
exit(1);
}
fromp->sin_port = htons(port);
if (connect(s, (struct sockaddr *)fromp, sizeof (*fromp)) < 0) {
syslog(LOG_INFO, "connect second port %d: %m", port);
exit(1);
}
}
if (vacuous) {
error("rshd: remote host requires Kerberos authentication\n");
exit(1);
}
errorstr = NULL;
inaddr2str (fromp->sin_addr, remotehost, sizeof(remotehost));
if (use_kerberos) {
kdata = &authbuf;
ticket = &tickbuf;
authopts = 0L;
k_getsockinst(0, instance, sizeof(instance));
version[VERSION_SIZE - 1] = '\0';
if (doencrypt) {
struct sockaddr_in local_addr;
rc = sizeof(local_addr);
if (getsockname(0, (struct sockaddr *)&local_addr,
&rc) < 0) {
syslog(LOG_ERR, "getsockname: %m");
error("rlogind: getsockname: %m");
exit(1);
}
authopts = KOPT_DO_MUTUAL;
rc = krb_recvauth(authopts, 0, ticket,
"rcmd", instance, &fromaddr,
&local_addr, kdata, "", schedule,
version);
#ifndef NOENCRYPTION
des_set_key(&kdata->session, schedule);
#else
memset(schedule, 0, sizeof(schedule));
#endif
} else
rc = krb_recvauth(authopts, 0, ticket, "rcmd",
instance, &fromaddr,
(struct sockaddr_in *) 0,
kdata, "", 0, version);
if (rc != KSUCCESS) {
error("Kerberos authentication failure: %s\n",
krb_get_err_text(rc));
exit(1);
}
} else
xgetstr(remuser, sizeof(remuser), "remuser");
xgetstr(locuser, sizeof(locuser), "locuser");
xgetstr(cmdbuf, sizeof(cmdbuf), "command");
setpwent();
pwd = k_getpwnam(locuser);
if (pwd == NULL) {
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: unknown login. cmd='%.80s'",
remuser, remotehost, locuser, cmdbuf);
if (errorstr == NULL)
errorstr = "Login incorrect.\n";
goto fail;
}
if (pwd->pw_uid == 0 && strcmp("root", locuser) != 0)
{
syslog(LOG_ALERT, "NIS attack, user %s has uid 0", locuser);
if (errorstr == NULL)
errorstr = "Login incorrect.\n";
goto fail;
}
if (chdir(pwd->pw_dir) < 0) {
chdir("/");
#ifdef notdef
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: no home directory. cmd='%.80s'",
remuser, remotehost, locuser, cmdbuf);
error("No remote directory.\n");
exit(1);
#endif
}
if (use_kerberos) {
if (pwd->pw_passwd != 0 && *pwd->pw_passwd != '\0') {
if (kuserok(kdata, locuser) != 0) {
syslog(LOG_INFO|LOG_AUTH,
"Kerberos rsh denied to %s",
krb_unparse_name_long(kdata->pname,
kdata->pinst,
kdata->prealm));
error("Permission denied.\n");
exit(1);
}
}
} else
if (errorstr ||
pwd->pw_passwd != 0 && *pwd->pw_passwd != '\0' &&
iruserok(fromp->sin_addr.s_addr, pwd->pw_uid == 0,
remuser, locuser) < 0) {
if (__rcmd_errstr)
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: permission denied (%s). cmd='%.80s'",
remuser, remotehost, locuser,
__rcmd_errstr, cmdbuf);
else
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: permission denied. cmd='%.80s'",
remuser, remotehost, locuser, cmdbuf);
fail:
if (errorstr == NULL)
errorstr = "Permission denied.\n";
error(errorstr, errorhost);
exit(1);
}
if (pwd->pw_uid && !access(_PATH_NOLOGIN, F_OK)) {
error("Logins currently disabled.\n");
exit(1);
}
write(STDERR_FILENO, "\0", 1);
sent_null = 1;
if (port) {
if (pipe(pv) < 0) {
error("Can't make pipe.\n");
exit(1);
}
if (doencrypt) {
if (pipe(pv1) < 0) {
error("Can't make 2nd pipe.\n");
exit(1);
}
if (pipe(pv2) < 0) {
error("Can't make 3rd pipe.\n");
exit(1);
}
}
pid = fork();
if (pid == -1) {
error("Can't fork; try again.\n");
exit(1);
}
if (pid) {
if (doencrypt) {
static char msg[] = SECURE_MESSAGE;
close(pv1[1]);
close(pv2[0]);
#ifndef NOENCRYPTION
des_enc_write(s, msg, sizeof(msg) - 1, schedule, &kdata->session);
#else
write(s, msg, sizeof(msg) - 1);
#endif
} else {
close(0);
close(1);
}
close(2);
close(pv[1]);
FD_ZERO(&readfrom);
FD_SET(s, &readfrom);
FD_SET(pv[0], &readfrom);
if (pv[0] > s)
nfd = pv[0];
else
nfd = s;
if (doencrypt) {
FD_ZERO(&writeto);
FD_SET(pv2[1], &writeto);
FD_SET(pv1[0], &readfrom);
FD_SET(STDIN_FILENO, &readfrom);
nfd = max(nfd, pv2[1]);
nfd = max(nfd, pv1[0]);
} else
ioctl(pv[0], FIONBIO, (char *)&one);
/* should set s nbio! */
nfd++;
do {
ready = readfrom;
if (doencrypt) {
wready = writeto;
if (select(nfd, &ready,
&wready, 0,
(struct timeval *) 0) < 0)
break;
} else
if (select(nfd, &ready, 0,
0, (struct timeval *)0) < 0)
break;
if (FD_ISSET(s, &ready)) {
int ret;
if (doencrypt)
#ifndef NOENCRYPTION
ret = des_enc_read(s, &sig, 1, schedule, &kdata->session);
#else
ret = read(s, &sig, 1);
#endif
else
ret = read(s, &sig, 1);
if (ret <= 0)
FD_CLR(s, &readfrom);
else
kill(-pid, sig);
}
if (FD_ISSET(pv[0], &ready)) {
errno = 0;
cc = read(pv[0], buf, sizeof(buf));
if (cc <= 0) {
shutdown(s, 1+1);
FD_CLR(pv[0], &readfrom);
} else {
if (doencrypt)
#ifndef NOENCRYPTION
des_enc_write(s, buf, cc, schedule, &kdata->session);
#else
write(s, buf, cc);
#endif
else
(void)
write(s, buf, cc);
}
}
if (doencrypt && FD_ISSET(pv1[0], &ready)) {
errno = 0;
cc = read(pv1[0], buf, sizeof(buf));
if (cc <= 0) {
shutdown(pv1[0], 1+1);
FD_CLR(pv1[0], &readfrom);
} else
#ifndef NOENCRYPTION
des_enc_write(STDOUT_FILENO, buf, cc, schedule, &kdata->session);
#else
write(STDOUT_FILENO, buf, cc);
#endif
}
if (doencrypt
&& FD_ISSET(STDIN_FILENO, &ready)
&& FD_ISSET(pv2[1], &wready)) {
errno = 0;
#ifndef NOENCRYPTION
cc = des_enc_read(STDIN_FILENO, buf, sizeof(buf), schedule, &kdata->session);
#else
cc = read(STDIN_FILENO, buf, sizeof(buf));
#endif
if (cc <= 0) {
shutdown(STDIN_FILENO, 0);
FD_CLR(STDIN_FILENO, &readfrom);
close(pv2[1]);
FD_CLR(pv2[1], &writeto);
} else
write(pv2[1], buf, cc);
}
} while (FD_ISSET(s, &readfrom) ||
(doencrypt && FD_ISSET(pv1[0], &readfrom)) ||
FD_ISSET(pv[0], &readfrom));
exit(0);
}
setsid();
close(s);
close(pv[0]);
if (doencrypt) {
close(pv1[0]);
close(pv2[1]);
dup2(pv1[1], 1);
dup2(pv2[0], 0);
close(pv1[1]);
close(pv2[0]);
}
dup2(pv[1], 2);
close(pv[1]);
}
if (*pwd->pw_shell == '\0')
pwd->pw_shell = _PATH_BSHELL;
#ifdef HAVE_SETLOGIN
if (setlogin(pwd->pw_name) < 0)
syslog(LOG_ERR, "setlogin() failed: %m");
#endif
#ifdef HAVE_SETPCRED
if (setpcred (pwd->pw_name, NULL) == -1)
syslog(LOG_ERR, "setpcred() failure: %m");
#endif /* HAVE_SETPCRED */
setgid((gid_t)pwd->pw_gid);
initgroups(pwd->pw_name, pwd->pw_gid);
setuid((uid_t)pwd->pw_uid);
strncat(homedir, pwd->pw_dir, sizeof(homedir)-6);
/* Need to extend path to find rcp */
strncat(path, BINDIR, sizeof(path)-1);
strncat(path, ":", sizeof(path)-1);
strncat(path, _PATH_DEFPATH, sizeof(path)-1);
path[sizeof(path)-1] = '\0';
strncat(shell, pwd->pw_shell, sizeof(shell)-7);
strncat(username, pwd->pw_name, sizeof(username)-6);
cp = strrchr(pwd->pw_shell, '/');
if (cp)
cp++;
else
cp = pwd->pw_shell;
endpwent();
if (log_success || pwd->pw_uid == 0) {
if (use_kerberos)
syslog(LOG_INFO|LOG_AUTH,
"Kerberos shell from %s on %s as %s, cmd='%.80s'",
krb_unparse_name_long(kdata->pname,
kdata->pinst,
kdata->prealm),
remotehost, locuser, cmdbuf);
else
syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'",
remuser, remotehost, locuser, cmdbuf);
}
if (k_hasafs()) {
if (new_pag)
k_setpag(); /* Put users process in an new pag */
k_afsklog(0, 0);
}
execle(pwd->pw_shell, cp, "-c", cmdbuf, 0, envinit);
err(1, pwd->pw_shell);
}
/*
* Report error to client. Note: can't be used until second socket has
* connected to client, or older clients will hang waiting for that
* connection first.
*/
static void
error(const char *fmt, ...)
{
va_list ap;
int len;
char *bp, buf[BUFSIZ];
va_start(ap, fmt);
bp = buf;
if (sent_null == 0) {
*bp++ = 1;
len = 1;
} else
len = 0;
len = vsnprintf (bp, sizeof(buf) - len, fmt, ap);
write (STDERR_FILENO, buf, len);
va_end(ap);
}
static void
usage()
{
syslog(LOG_ERR,
"usage: rshd [-alnkvxLPi] [-p port]");
exit(2);
}
|