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freebsd-skq/libexec/rshd/rshd.c
Peter Wemm 7f3dea244c $Id$ -> $FreeBSD$
1999-08-28 00:22:10 +00:00

818 lines
18 KiB
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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.
*/
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1988, 1989, 1992, 1993, 1994\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static const char sccsid[] = "@(#)rshd.c 8.2 (Berkeley) 4/6/94";
#endif
static const char rcsid[] =
"$FreeBSD$";
#endif /* not lint */
/*
* remote shell server:
* [port]\0
* remuser\0
* locuser\0
* command\0
* data
*/
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#ifdef LOGIN_CAP
#include <login_cap.h>
#endif
int keepalive = 1;
int log_success; /* If TRUE, log all successful accesses */
int sent_null;
int no_delay;
void doit __P((struct sockaddr_in *));
void error __P((const char *, ...));
void getstr __P((char *, int, char *));
int local_domain __P((char *));
char *topdomain __P((char *));
void usage __P((void));
#ifdef KERBEROS
#include <des.h>
#include <krb.h>
#define VERSION_SIZE 9
#define SECURE_MESSAGE "This rsh session is using DES encryption for all transmissions.\r\n"
#define OPTIONS "alnkvxDL"
char authbuf[sizeof(AUTH_DAT)];
char tickbuf[sizeof(KTEXT_ST)];
int doencrypt, use_kerberos, vacuous;
Key_schedule schedule;
#else
#define OPTIONS "alnDL"
#endif
int
main(argc, argv)
int argc;
char *argv[];
{
extern int __check_rhosts_file;
struct linger linger;
int ch, on = 1, fromlen;
struct sockaddr_in from;
openlog("rshd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
opterr = 0;
while ((ch = getopt(argc, argv, OPTIONS)) != -1)
switch (ch) {
case 'a':
/* ignored for compatability */
break;
case 'l':
__check_rhosts_file = 0;
break;
case 'n':
keepalive = 0;
break;
#ifdef KERBEROS
case 'k':
use_kerberos = 1;
break;
case 'v':
vacuous = 1;
break;
#ifdef CRYPT
case 'x':
doencrypt = 1;
break;
#endif
#endif
case 'D':
no_delay = 1;
break;
case 'L':
log_success = 1;
break;
case '?':
default:
usage();
break;
}
argc -= optind;
argv += optind;
#ifdef KERBEROS
if (use_kerberos && vacuous) {
syslog(LOG_ERR, "only one of -k and -v allowed");
exit(2);
}
#ifdef CRYPT
if (doencrypt && !use_kerberos) {
syslog(LOG_ERR, "-k is required for -x");
exit(2);
}
#endif
#endif
fromlen = sizeof (from);
if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
syslog(LOG_ERR, "getpeername: %m");
exit(1);
}
if (keepalive &&
setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, (char *)&on,
sizeof(on)) < 0)
syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
linger.l_onoff = 1;
linger.l_linger = 60; /* XXX */
if (setsockopt(0, SOL_SOCKET, SO_LINGER, (char *)&linger,
sizeof (linger)) < 0)
syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m");
if (no_delay &&
setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
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};
char **environ;
void
doit(fromp)
struct sockaddr_in *fromp;
{
extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */
struct passwd *pwd;
u_short port;
fd_set ready, readfrom;
int cc, nfd, pv[2], pid, s;
int one = 1;
char *errorstr;
char *cp, sig, buf[BUFSIZ];
char cmdbuf[NCARGS+1], locuser[16], remuser[16];
char fromhost[MAXHOSTNAMELEN];
#ifdef LOGIN_CAP
login_cap_t *lc;
#endif
#ifdef KERBEROS
AUTH_DAT *kdata = (AUTH_DAT *) NULL;
KTEXT ticket = (KTEXT) NULL;
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;
#endif
(void) signal(SIGINT, SIG_DFL);
(void) signal(SIGQUIT, SIG_DFL);
(void) signal(SIGTERM, SIG_DFL);
#ifdef DEBUG
{ int t = open(_PATH_TTY, 2);
if (t >= 0) {
ioctl(t, TIOCNOTTY, (char *)0);
(void) 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)",
fromp->sin_family);
exit(1);
}
#ifdef IP_OPTIONS
{
u_char optbuf[BUFSIZ/3];
int optsize = sizeof(optbuf), ipproto, i;
struct protoent *ip;
if ((ip = getprotobyname("ip")) != NULL)
ipproto = ip->p_proto;
else
ipproto = IPPROTO_IP;
if (!getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf, &optsize) &&
optsize != 0) {
for (i = 0; i < optsize; ) {
u_char c = optbuf[i];
if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
syslog(LOG_NOTICE,
"connection refused from %s with IP option %s",
inet_ntoa(fromp->sin_addr),
c == IPOPT_LSRR ? "LSRR" : "SSRR");
exit(1);
}
if (c == IPOPT_EOL)
break;
i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
}
}
}
#endif
#ifdef KERBEROS
if (!use_kerberos)
#endif
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);
}
(void) alarm(60);
port = 0;
s = 0; /* not set or used if 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';
}
(void) 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);
}
#ifdef KERBEROS
if (!use_kerberos)
#endif
if (port >= IPPORT_RESERVED ||
port < IPPORT_RESERVED/2) {
syslog(LOG_NOTICE|LOG_AUTH,
"2nd socket from %s on unreserved port %u",
inet_ntoa(fromp->sin_addr),
port);
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);
}
}
#ifdef KERBEROS
if (vacuous) {
error("rshd: remote host requires Kerberos authentication\n");
exit(1);
}
#endif
#ifdef notdef
/* from inetd, socket is already on 0, 1, 2 */
dup2(f, 0);
dup2(f, 1);
dup2(f, 2);
#endif
errorstr = NULL;
realhostname(fromhost, sizeof(fromhost) - 1, &fromp->sin_addr);
fromhost[sizeof(fromhost) - 1] = '\0';
#ifdef KERBEROS
if (use_kerberos) {
kdata = (AUTH_DAT *) authbuf;
ticket = (KTEXT) tickbuf;
authopts = 0L;
strcpy(instance, "*");
version[VERSION_SIZE - 1] = '\0';
#ifdef CRYPT
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);
des_set_key(&kdata->session, schedule);
} else
#endif
rc = krb_recvauth(authopts, 0, ticket, "rcmd",
instance, &fromaddr,
(struct sockaddr_in *) 0,
kdata, "", NULL, version);
if (rc != KSUCCESS) {
error("Kerberos authentication failure: %s\n",
krb_err_txt[rc]);
exit(1);
}
} else
#endif
getstr(remuser, sizeof(remuser), "remuser");
getstr(locuser, sizeof(locuser), "locuser");
getstr(cmdbuf, sizeof(cmdbuf), "command");
setpwent();
pwd = getpwnam(locuser);
if (pwd == NULL) {
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: unknown login. cmd='%.80s'",
remuser, fromhost, locuser, cmdbuf);
if (errorstr == NULL)
errorstr = "Login incorrect.\n";
goto fail;
}
#ifdef LOGIN_CAP
lc = login_getpwclass(pwd);
#endif
if (chdir(pwd->pw_dir) < 0) {
#ifdef LOGIN_CAP
if (chdir("/") < 0 ||
login_getcapbool(lc, "requirehome", !!pwd->pw_uid)) {
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: no home directory. cmd='%.80s'",
remuser, fromhost, locuser, cmdbuf);
error("No remote home directory.\n");
exit(0);
}
#else
(void) chdir("/");
#ifdef notdef
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: no home directory. cmd='%.80s'",
remuser, fromhost, locuser, cmdbuf);
error("No remote directory.\n");
exit(1);
#endif
#endif
pwd->pw_dir = "/";
}
#ifdef KERBEROS
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.%s@%s",
kdata->pname, kdata->pinst, kdata->prealm);
error("Login incorrect.\n");
exit(1);
}
}
} else
#endif
if (errorstr ||
(pwd->pw_expire && time(NULL) >= pwd->pw_expire) ||
(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, fromhost, locuser, __rcmd_errstr,
cmdbuf);
else
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: permission denied. cmd='%.80s'",
remuser, fromhost, locuser, cmdbuf);
fail:
if (errorstr == NULL)
errorstr = "Login incorrect.\n";
error(errorstr, fromhost);
exit(1);
}
if (pwd->pw_uid && !access(_PATH_NOLOGIN, F_OK)) {
error("Logins currently disabled.\n");
exit(1);
}
#ifdef LOGIN_CAP
if (lc != NULL) {
char remote_ip[MAXHOSTNAMELEN];
strncpy(remote_ip, inet_ntoa(fromp->sin_addr),
sizeof(remote_ip) - 1);
remote_ip[sizeof(remote_ip) - 1] = 0;
if (!auth_hostok(lc, fromhost, remote_ip)) {
syslog(LOG_INFO|LOG_AUTH,
"%s@%s as %s: permission denied (%s). cmd='%.80s'",
remuser, fromhost, locuser, __rcmd_errstr,
cmdbuf);
error("Login incorrect.\n");
exit(1);
}
if (!auth_timeok(lc, time(NULL))) {
error("Logins not available right now\n");
exit(1);
}
}
#endif /* !LOGIN_CAP */
#if BSD > 43
/* before fork, while we're session leader */
if (setlogin(pwd->pw_name) < 0)
syslog(LOG_ERR, "setlogin() failed: %m");
#endif
(void) write(STDERR_FILENO, "\0", 1);
sent_null = 1;
if (port) {
if (pipe(pv) < 0) {
error("Can't make pipe.\n");
exit(1);
}
#ifdef CRYPT
#ifdef KERBEROS
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);
}
}
#endif
#endif
pid = fork();
if (pid == -1) {
error("Can't fork; try again.\n");
exit(1);
}
if (pid) {
#ifdef CRYPT
#ifdef KERBEROS
if (doencrypt) {
static char msg[] = SECURE_MESSAGE;
(void) close(pv1[1]);
(void) close(pv2[1]);
des_enc_write(s, msg, sizeof(msg) - 1,
schedule, &kdata->session);
} else
#endif
#endif
{
(void) close(0);
(void) close(1);
}
(void) close(2);
(void) 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;
#ifdef CRYPT
#ifdef KERBEROS
if (doencrypt) {
FD_ZERO(&writeto);
FD_SET(pv2[0], &writeto);
FD_SET(pv1[0], &readfrom);
nfd = MAX(nfd, pv2[0]);
nfd = MAX(nfd, pv1[0]);
} else
#endif
#endif
ioctl(pv[0], FIONBIO, (char *)&one);
/* should set s nbio! */
nfd++;
do {
ready = readfrom;
#ifdef CRYPT
#ifdef KERBEROS
if (doencrypt) {
wready = writeto;
if (select(nfd, &ready,
&wready, (fd_set *) 0,
(struct timeval *) 0) < 0)
break;
} else
#endif
#endif
if (select(nfd, &ready, (fd_set *)0,
(fd_set *)0, (struct timeval *)0) < 0)
break;
if (FD_ISSET(s, &ready)) {
int ret;
#ifdef CRYPT
#ifdef KERBEROS
if (doencrypt)
ret = des_enc_read(s, &sig, 1,
schedule, &kdata->session);
else
#endif
#endif
ret = read(s, &sig, 1);
if (ret <= 0)
FD_CLR(s, &readfrom);
else
killpg(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 {
#ifdef CRYPT
#ifdef KERBEROS
if (doencrypt)
(void)
des_enc_write(s, buf, cc,
schedule, &kdata->session);
else
#endif
#endif
(void)
write(s, buf, cc);
}
}
#ifdef CRYPT
#ifdef KERBEROS
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
(void) des_enc_write(STDOUT_FILENO,
buf, cc,
schedule, &kdata->session);
}
if (doencrypt && FD_ISSET(pv2[0], &wready)) {
errno = 0;
cc = des_enc_read(STDIN_FILENO,
buf, sizeof(buf),
schedule, &kdata->session);
if (cc <= 0) {
shutdown(pv2[0], 1+1);
FD_CLR(pv2[0], &writeto);
} else
(void) write(pv2[0], buf, cc);
}
#endif
#endif
} while (FD_ISSET(s, &readfrom) ||
#ifdef CRYPT
#ifdef KERBEROS
(doencrypt && FD_ISSET(pv1[0], &readfrom)) ||
#endif
#endif
FD_ISSET(pv[0], &readfrom));
exit(0);
}
setpgrp(0, getpid());
(void) close(s);
(void) close(pv[0]);
#ifdef CRYPT
#ifdef KERBEROS
if (doencrypt) {
close(pv1[0]); close(pv2[0]);
dup2(pv1[1], 1);
dup2(pv2[1], 0);
close(pv1[1]);
close(pv2[1]);
}
#endif
#endif
dup2(pv[1], 2);
close(pv[1]);
}
if (*pwd->pw_shell == '\0')
pwd->pw_shell = _PATH_BSHELL;
environ = envinit;
strncat(homedir, pwd->pw_dir, sizeof(homedir)-6);
strcat(path, _PATH_DEFPATH);
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;
#ifdef LOGIN_CAP
if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETALL) != 0) {
syslog(LOG_ERR, "setusercontext: %m");
exit(1);
}
login_close(lc);
#else
(void) setgid((gid_t)pwd->pw_gid);
initgroups(pwd->pw_name, pwd->pw_gid);
(void) setuid((uid_t)pwd->pw_uid);
#endif
endpwent();
if (log_success || pwd->pw_uid == 0) {
#ifdef KERBEROS
if (use_kerberos)
syslog(LOG_INFO|LOG_AUTH,
"Kerberos shell from %s.%s@%s on %s as %s, cmd='%.80s'",
kdata->pname, kdata->pinst, kdata->prealm,
fromhost, locuser, cmdbuf);
else
#endif
syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'",
remuser, fromhost, locuser, cmdbuf);
}
execl(pwd->pw_shell, cp, "-c", cmdbuf, 0);
perror(pwd->pw_shell);
exit(1);
}
/*
* 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.
*/
#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
void
#if __STDC__
error(const char *fmt, ...)
#else
error(fmt, va_alist)
char *fmt;
va_dcl
#endif
{
va_list ap;
int len;
char *bp, buf[BUFSIZ];
#if __STDC__
va_start(ap, fmt);
#else
va_start(ap);
#endif
bp = buf;
if (sent_null == 0) {
*bp++ = 1;
len = 1;
} else
len = 0;
(void)vsnprintf(bp, sizeof(buf) - 1, fmt, ap);
(void)write(STDERR_FILENO, buf, len + strlen(bp));
}
void
getstr(buf, cnt, err)
char *buf, *err;
int cnt;
{
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);
}
/*
* Check whether host h is in our local domain,
* defined as sharing the last two components of the domain part,
* or the entire domain part if the local domain has only one component.
* If either name is unqualified (contains no '.'),
* assume that the host is local, as it will be
* interpreted as such.
*/
int
local_domain(h)
char *h;
{
char localhost[MAXHOSTNAMELEN];
char *p1, *p2;
localhost[0] = 0;
(void) gethostname(localhost, sizeof(localhost) - 1);
localhost[sizeof(localhost) - 1] = '\0';
p1 = topdomain(localhost);
p2 = topdomain(h);
if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2))
return (1);
return (0);
}
char *
topdomain(h)
char *h;
{
char *p, *maybe = NULL;
int dots = 0;
for (p = h + strlen(h); p >= h; p--) {
if (*p == '.') {
if (++dots == 2)
return (p);
maybe = p;
}
}
return (maybe);
}
void
usage()
{
syslog(LOG_ERR, "usage: rshd [-%s]", OPTIONS);
exit(2);
}
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