OpenBSD-4.6/usr.sbin/sliplogin/sliplogin.c
/*-
* Copyright (c) 1990 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. 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
char copyright[] =
"@(#) Copyright (c) 1990 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */
#ifndef lint
/*static char sccsid[] = "from: @(#)sliplogin.c 5.6 (Berkeley) 3/2/91";*/
static char rcsid[] = "$Id: sliplogin.c,v 1.28 2007/09/14 14:29:20 chl Exp $";
#endif /* not lint */
/*
* sliplogin.c
* [MUST BE RUN SUID, SLOPEN DOES A SUSER()!]
*
* This program initializes its own tty port to be an async TCP/IP interface.
* It sets the line discipline to slip, invokes a shell script to initialize
* the network interface, then pauses forever waiting for hangup.
*
* It is a remote descendant of several similar programs with incestuous ties:
* - Kirk Smith's slipconf, modified by Richard Johnsson @ DEC WRL.
* - slattach, probably by Rick Adams but touched by countless hordes.
* - the original sliplogin for 4.2bsd, Doug Kingston the mover behind it.
*
* There are two forms of usage:
*
* "sliplogin"
* Invoked simply as "sliplogin", the program looks up the username
* in the file /etc/slip.hosts.
* If an entry is found, the line on fd0 is configured for SLIP operation
* as specified in the file.
*
* "sliplogin IPhostlogin </dev/ttyb"
* Invoked by root with a username, the name is looked up in the
* /etc/slip.hosts file and if found fd0 is configured as in case 1.
*/
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/syslog.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <signal.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <ttyent.h>
#include <net/slip.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "pathnames.h"
extern char **environ;
static char *restricted_environ[] = {
"PATH=" _PATH_STDPATH,
NULL
};
int unit;
int speed;
uid_t uid;
char loginargs[BUFSIZ];
char loginfile[MAXPATHLEN];
char loginname[BUFSIZ];
void
findid(char *name)
{
FILE *fp;
static char slopt[5][16];
static char laddr[16];
static char raddr[16];
static char mask[16];
char user[MAXLOGNAME];
int n;
strlcpy(loginname, name, sizeof loginname);
if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) {
syslog(LOG_ERR, "%s: %m", _PATH_ACCESS);
err(1, "%s", _PATH_ACCESS);
}
while (fgets(loginargs, sizeof(loginargs), fp)) {
if (ferror(fp))
break;
loginargs[strcspn(loginargs, "#")] = '\0';
loginargs[strcspn(loginargs, "\n")] = '\0';
n = sscanf(loginargs, "%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s\n",
user, laddr, raddr, mask, slopt[0], slopt[1],
slopt[2], slopt[3], slopt[4]);
if (strcmp(user, name) != 0)
continue;
/*
* we've found the guy we're looking for -- see if
* there's a login file we can use. First check for
* one specific to this host. If none found, try for
* a generic one.
*/
(void)snprintf(loginfile, sizeof loginfile, "%s.%s",
_PATH_LOGIN, name);
if (access(loginfile, R_OK|X_OK) != 0) {
(void)strlcpy(loginfile, _PATH_LOGIN, sizeof(loginfile));
if (access(loginfile, R_OK|X_OK)) {
fputs("access denied - no login file\n",
stderr);
syslog(LOG_ERR,
"access denied for %s - no %s",
name, _PATH_LOGIN);
exit(5);
}
}
(void) fclose(fp);
return;
}
syslog(LOG_ERR, "SLIP access denied for %s", name);
errx(1, "SLIP access denied for %s", name);
/* NOTREACHED */
}
const char *
sigstr(int s)
{
if (s > 0 && s < NSIG)
return(sys_signame[s]);
else {
static char buf[32];
(void)snprintf(buf, sizeof buf, "sig %d", s);
return(buf);
}
}
volatile sig_atomic_t die;
/* ARGSUSED */
void
hup_handler(int signo)
{
die = 1;
}
int
main(int argc, char *argv[])
{
int fd, s, ldisc, odisc;
char *name;
struct termios tios, otios;
char logoutfile[MAXPATHLEN], logincmd[2*BUFSIZ+32];
sigset_t emptyset;
environ = restricted_environ; /* minimal protection for system() */
if ((name = strrchr(argv[0], '/')) == NULL)
name = argv[0];
else
name++;
closefrom(3);
if (argc > 1 && strlen(argv[1]) > MAXLOGNAME)
errx(1, "login %s too long", argv[1]);
openlog(name, LOG_PID, LOG_DAEMON);
uid = getuid();
if (argc > 1) {
findid(argv[1]);
/*
* Disassociate from current controlling terminal, if any,
* and ensure that the slip line is our controlling terminal.
*/
switch (fork()) {
case -1:
perror("fork");
exit(1);
case 0:
break;
default:
exit(0);
}
if (setsid() == -1)
perror("setsid");
if (argc > 2) {
if ((fd = open(argv[2], O_RDWR)) == -1) {
perror(argv[2]);
exit(2);
}
(void) dup2(fd, 0);
if (fd > 2)
close(fd);
}
#ifdef TIOCSCTTY
if (ioctl(STDIN_FILENO, TIOCSCTTY, (caddr_t)0) != 0)
perror("ioctl (TIOCSCTTY)");
#endif
} else {
if ((name = getlogin()) == NULL) {
syslog(LOG_ERR,
"access denied - getlogin returned 0");
errx(1, "access denied - no username");
}
findid(name);
}
if (!isatty(STDIN_FILENO)) {
syslog(LOG_ERR, "stdin not a tty");
errx(1, "stdin not a tty");
}
(void) fchmod(STDIN_FILENO, 0600);
warnx("starting slip login for %s", loginname);
/* set up the line parameters */
if (tcgetattr(STDIN_FILENO, &tios) < 0) {
syslog(LOG_ERR, "tcgetattr: %m");
exit(1);
}
otios = tios;
cfmakeraw(&tios);
tios.c_iflag &= ~IMAXBEL;
if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &tios) < 0) {
syslog(LOG_ERR, "tcsetattr: %m");
exit(1);
}
speed = cfgetispeed(&tios);
/* find out what ldisc we started with */
if (ioctl(STDIN_FILENO, TIOCGETD, (caddr_t)&odisc) < 0) {
syslog(LOG_ERR, "ioctl(TIOCGETD) (1): %m");
exit(1);
}
ldisc = SLIPDISC;
if (ioctl(STDIN_FILENO, TIOCSETD, (caddr_t)&ldisc) < 0) {
syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
exit(1);
}
/* find out what unit number we were assigned */
if (ioctl(STDIN_FILENO, SLIOCGUNIT, (caddr_t)&unit) < 0) {
syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m");
exit(1);
}
(void) signal(SIGHUP, hup_handler);
(void) signal(SIGTERM, hup_handler);
syslog(LOG_INFO, "attaching slip unit %d for %s", unit, loginname);
(void)snprintf(logincmd, sizeof(loginargs), "%s %d %d %s", loginfile,
unit, speed, loginargs);
/*
* aim stdout and errout at /dev/null so logincmd output won't
* babble into the slip tty line.
*/
(void) close(1);
if ((fd = open(_PATH_DEVNULL, O_WRONLY)) != 1) {
if (fd < 0) {
syslog(LOG_ERR, "open /dev/null: %m");
exit(1);
}
(void) dup2(fd, 1);
(void) close(fd);
}
(void) dup2(1, 2);
/*
* Run login and logout scripts as root (real and effective);
* current route(8) is setuid root, and checks the real uid
* to see whether changes are allowed (or just "route get").
*/
(void) setuid(0);
if ((s = system(logincmd))) {
syslog(LOG_ERR, "%s login failed: exit status %d from %s",
loginname, s, loginfile);
(void) ioctl(STDIN_FILENO, TIOCSETD, (caddr_t)&odisc);
(void) tcsetattr(STDIN_FILENO, TCSAFLUSH, &otios);
exit(6);
}
/* twiddle thumbs until we get a signal; allow user to kill */
seteuid(uid);
sigemptyset(&emptyset);
while (die == 0)
sigsuspend(&emptyset);
seteuid(0);
(void)snprintf(logoutfile, sizeof logoutfile, "%s.%s",
_PATH_LOGOUT, loginname);
if (access(logoutfile, R_OK|X_OK) != 0)
(void)strlcpy(logoutfile, _PATH_LOGOUT,
sizeof(logoutfile));
if (access(logoutfile, R_OK|X_OK) == 0) {
char logincmd[2*MAXPATHLEN+32];
(void) snprintf(logincmd, sizeof logincmd, "%s %d %d %s",
logoutfile, unit, speed, loginargs);
(void) system(logincmd);
}
close(0);
syslog(LOG_INFO, "closed %s slip unit %d (%s)",
loginname, unit, sigstr(s));
exit(1);
}