FreeBSD-5.3/libexec/rexecd/rexecd.c
/*
* 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[] = "@(#)rexecd.c 8.1 (Berkeley) 6/4/93";
#endif
static const char rcsid[] =
"$FreeBSD: src/libexec/rexecd/rexecd.c,v 1.31 2004/05/24 13:21:24 stefanf Exp $";
#endif /* not lint */
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <err.h>
#include <errno.h>
#include <libutil.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <security/pam_appl.h>
#include <security/openpam.h>
static pam_handle_t *pamh;
static struct pam_conv pamc = {
openpam_nullconv,
NULL
};
static int pam_flags = PAM_SILENT|PAM_DISALLOW_NULL_AUTHTOK;
static int pam_err;
#define pam_ok(err) ((pam_err = (err)) == PAM_SUCCESS)
char **environ;
char remote[MAXHOSTNAMELEN];
struct sockaddr_storage asin;
static void doit(struct sockaddr *);
static void getstr(char *, int, char *);
static void error(const char *fmt, ...);
int no_uid_0 = 1;
/*
* remote execute server:
* username\0
* password\0
* command\0
* data
*/
/*ARGSUSED*/
int
main(int argc, char *argv[])
{
struct sockaddr_storage from;
int fromlen;
int ch;
openlog("rexecd", LOG_PID, LOG_AUTH);
while ((ch = getopt(argc, argv, "i")) != -1)
switch (ch) {
case 'i':
no_uid_0 = 0;
break;
default:
syslog(LOG_ERR, "usage: rexecd [-i]");
exit(1);
}
argc -= optind;
argv += optind;
fromlen = sizeof (from);
if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0)
err(1, "getpeername");
realhostname_sa(remote, sizeof(remote) - 1,
(struct sockaddr *)&from, fromlen);
doit((struct sockaddr *)&from);
return(0);
}
static void
doit(struct sockaddr *fromp)
{
char cmdbuf[NCARGS+1], *cp;
const char *namep;
char user[16], pass[16];
struct passwd *pwd;
int fd, r, sd;
u_short port;
int pv[2], pid, cc, nfds;
fd_set rfds, fds;
char buf[BUFSIZ], sig;
int one = 1;
char **envlist, **env;
(void) signal(SIGINT, SIG_DFL);
(void) signal(SIGQUIT, SIG_DFL);
(void) signal(SIGTERM, SIG_DFL);
dup2(STDIN_FILENO, STDOUT_FILENO);
dup2(STDIN_FILENO, STDOUT_FILENO);
(void) alarm(60);
port = 0;
for (;;) {
char c;
if (read(STDIN_FILENO, &c, 1) != 1)
exit(1);
if (c == 0)
break;
port = port * 10 + c - '0';
}
if (port != 0) {
sd = socket(fromp->sa_family, SOCK_STREAM, 0);
if (sd < 0)
exit(1);
bzero(&asin, sizeof(asin));
asin.ss_family = fromp->sa_family;
asin.ss_len = fromp->sa_len;
if (bind(sd, (struct sockaddr *)&asin, asin.ss_len) < 0)
exit(1);
switch (fromp->sa_family) {
case AF_INET:
((struct sockaddr_in *)fromp)->sin_port = htons(port);
break;
case AF_INET6:
((struct sockaddr_in6 *)fromp)->sin6_port = htons(port);
break;
default:
exit(1);
}
if (connect(sd, fromp, fromp->sa_len) < 0)
exit(1);
}
getstr(user, sizeof(user), "username");
getstr(pass, sizeof(pass), "password");
getstr(cmdbuf, sizeof(cmdbuf), "command");
(void) alarm(0);
if ((pwd = getpwnam(user)) == NULL || (pwd->pw_uid = 0 && no_uid_0) ||
!pam_ok(pam_start("rexecd", user, &pamc, &pamh)) ||
!pam_ok(pam_set_item(pamh, PAM_RHOST, remote)) ||
!pam_ok(pam_set_item(pamh, PAM_AUTHTOK, pass)) ||
!pam_ok(pam_authenticate(pamh, pam_flags)) ||
!pam_ok(pam_acct_mgmt(pamh, pam_flags))) {
syslog(LOG_ERR, "%s LOGIN REFUSED from %s", user, remote);
error("Login incorrect.\n");
exit(1);
}
syslog(LOG_INFO, "login from %s as %s", remote, user);
(void) write(STDERR_FILENO, "\0", 1);
if (port != 0) {
(void) pipe(pv);
pid = fork();
if (pid == -1) {
error("Try again.\n");
exit(1);
}
if (pid) {
/* parent */
(void) pam_end(pamh, pam_err);
(void) close(STDIN_FILENO);
(void) close(STDOUT_FILENO);
(void) close(STDERR_FILENO);
(void) close(pv[1]);
ioctl(pv[0], FIONBIO, (char *)&one);
/* should set sd nbio! */
FD_ZERO(&fds);
FD_SET(sd, &fds);
nfds = sd + 1;
FD_SET(pv[0], &fds);
if (pv[0] >= nfds)
nfds = pv[0] + 1;
do {
rfds = fds;
for (;;) {
r = select(nfds, &rfds, NULL, NULL, NULL);
if (r > 0)
break;
if (r < 0 && errno != EINTR)
exit(0);
}
if (FD_ISSET(sd, &rfds)) {
if (read(sd, &sig, 1) <= 0)
FD_CLR(sd, &fds);
else
killpg(pid, sig);
}
if (FD_ISSET(pv[0], &fds)) {
cc = read(pv[0], buf, sizeof (buf));
if (cc <= 0) {
shutdown(sd, SHUT_RDWR);
FD_CLR(pv[0], &fds);
} else {
(void) write(sd, buf, cc);
}
}
} while (FD_ISSET(sd, &fds) || FD_ISSET(pv[0], &fds));
exit(0);
}
/* child */
(void) close(sd);
(void) close(pv[0]);
dup2(pv[1], 2);
}
for (fd = getdtablesize(); fd > 2; fd--)
(void) close(fd);
if (*pwd->pw_shell == '\0')
pwd->pw_shell = _PATH_BSHELL;
if (setsid() == -1)
syslog(LOG_ERR, "setsid() failed: %m");
if (setlogin(pwd->pw_name) < 0)
syslog(LOG_ERR, "setlogin() failed: %m");
(void) setgid((gid_t)pwd->pw_gid);
initgroups(pwd->pw_name, pwd->pw_gid);
if (!pam_ok(pam_setcred(pamh, PAM_ESTABLISH_CRED)))
syslog(LOG_ERR, "pam_setcred() failed: %s",
pam_strerror(pamh, pam_err));
(void) pam_setenv(pamh, "HOME", pwd->pw_dir, 1);
(void) pam_setenv(pamh, "SHELL", pwd->pw_shell, 1);
(void) pam_setenv(pamh, "USER", pwd->pw_name, 1);
(void) pam_setenv(pamh, "PATH", _PATH_DEFPATH, 1);
environ = pam_getenvlist(pamh);
(void) pam_end(pamh, pam_err);
(void) setuid((uid_t)pwd->pw_uid);
cp = strrchr(pwd->pw_shell, '/');
if (cp)
cp++;
else
cp = pwd->pw_shell;
if (chdir(pwd->pw_dir) < 0) {
error("No remote directory.\n");
exit(1);
}
execl(pwd->pw_shell, cp, "-c", cmdbuf, (char *)0);
err(1, "%s", pwd->pw_shell);
}
static void
error(const char *fmt, ...)
{
char buf[BUFSIZ];
va_list ap;
va_start(ap, fmt);
buf[0] = 1;
(void)vsnprintf(buf + 1, sizeof(buf) - 1, fmt, ap);
(void)write(STDERR_FILENO, buf, strlen(buf));
va_end(ap);
}
static void
getstr(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);
}