FreeBSD-5.3/usr.sbin/sliplogin/sliplogin.c
/*-
* Copyright (c) 1990, 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.
* 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 char copyright[] =
"@(#) Copyright (c) 1990, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)sliplogin.c 8.2 (Berkeley) 2/1/94";
static char rscid[] = "@(#)$FreeBSD: src/usr.sbin/sliplogin/sliplogin.c,v 1.15 2004/08/07 04:28:55 imp 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 <syslog.h>
#include <netdb.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <net/slip.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <paths.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include "pathnames.h"
extern char **environ;
static char *restricted_environ[] = {
"PATH=" _PATH_STDPATH,
NULL
};
int unit;
int slip_mode;
speed_t speed;
int uid;
int keepal;
int outfill;
int slunit;
char loginargs[BUFSIZ];
char loginfile[MAXPATHLEN];
char loginname[BUFSIZ];
static char raddr[32]; /* remote address */
char ifname[IFNAMSIZ]; /* interface name */
static char pidfilename[MAXPATHLEN]; /* name of pid file */
static char iffilename[MAXPATHLEN]; /* name of if file */
static pid_t pid; /* our pid */
char *
make_ipaddr(void)
{
static char address[20] ="";
struct hostent *he;
unsigned long ipaddr;
address[0] = '\0';
if ((he = gethostbyname(raddr)) != NULL) {
ipaddr = ntohl(*(long *)he->h_addr_list[0]);
sprintf(address, "%lu.%lu.%lu.%lu",
ipaddr >> 24,
(ipaddr & 0x00ff0000) >> 16,
(ipaddr & 0x0000ff00) >> 8,
(ipaddr & 0x000000ff));
}
return address;
}
struct slip_modes {
char *sm_name;
int sm_or_flag;
int sm_and_flag;
} modes[] = {
"normal", 0 , 0 ,
"compress", IFF_LINK0, IFF_LINK2,
"noicmp", IFF_LINK1, 0 ,
"autocomp", IFF_LINK2, IFF_LINK0,
};
void
findid(name)
char *name;
{
FILE *fp;
static char slopt[5][16];
static char laddr[16];
static char mask[16];
char slparmsfile[MAXPATHLEN];
char user[16];
char buf[128];
int i, j, n;
environ = restricted_environ; /* minimal protection for system() */
(void)strncpy(loginname, name, sizeof(loginname)-1);
loginname[sizeof(loginname)-1] = '\0';
if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) {
accfile_err:
syslog(LOG_ERR, "%s: %m\n", _PATH_ACCESS);
exit(1);
}
while (fgets(loginargs, sizeof(loginargs) - 1, fp)) {
if (ferror(fp))
goto accfile_err;
if (loginargs[0] == '#' || isspace(loginargs[0]))
continue;
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 (n < 4) {
syslog(LOG_ERR, "%s: wrong format\n", _PATH_ACCESS);
exit(1);
}
if (strcmp(user, name) != 0)
continue;
(void) fclose(fp);
slip_mode = 0;
for (i = 0; i < n - 4; i++) {
for (j = 0; j < sizeof(modes)/sizeof(struct slip_modes);
j++) {
if (strcmp(modes[j].sm_name, slopt[i]) == 0) {
slip_mode |= (modes[j].sm_or_flag);
slip_mode &= ~(modes[j].sm_and_flag);
break;
}
}
}
/*
* 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_SLIP_LOGIN, name);
if (access(loginfile, R_OK|X_OK) != 0) {
(void)strncpy(loginfile, _PATH_SLIP_LOGIN,
sizeof(loginfile) - 1);
loginfile[sizeof(loginfile) - 1] = '\0';
if (access(loginfile, R_OK|X_OK)) {
syslog(LOG_ERR,
"access denied for %s - no %s\n",
name, _PATH_SLIP_LOGIN);
exit(5);
}
}
(void)snprintf(slparmsfile, sizeof(slparmsfile), "%s.%s", _PATH_SLPARMS, name);
if (access(slparmsfile, R_OK|X_OK) != 0) {
(void)strncpy(slparmsfile, _PATH_SLPARMS, sizeof(slparmsfile)-1);
slparmsfile[sizeof(slparmsfile)-1] = '\0';
if (access(slparmsfile, R_OK|X_OK))
*slparmsfile = '\0';
}
keepal = outfill = 0;
slunit = -1;
if (*slparmsfile) {
if ((fp = fopen(slparmsfile, "r")) == NULL) {
slfile_err:
syslog(LOG_ERR, "%s: %m\n", slparmsfile);
exit(1);
}
n = 0;
while (fgets(buf, sizeof(buf) - 1, fp) != NULL) {
if (ferror(fp))
goto slfile_err;
if (buf[0] == '#' || isspace(buf[0]))
continue;
n = sscanf(buf, "%d %d %d", &keepal, &outfill, &slunit);
if (n < 1) {
slwrong_fmt:
syslog(LOG_ERR, "%s: wrong format\n", slparmsfile);
exit(1);
}
(void) fclose(fp);
break;
}
if (n == 0)
goto slwrong_fmt;
}
return;
}
syslog(LOG_ERR, "SLIP access denied for %s\n", name);
exit(4);
/* NOTREACHED */
}
char *
sigstr(s)
int s;
{
static char buf[32];
switch (s) {
case SIGHUP: return("HUP");
case SIGINT: return("INT");
case SIGQUIT: return("QUIT");
case SIGILL: return("ILL");
case SIGTRAP: return("TRAP");
case SIGIOT: return("IOT");
case SIGEMT: return("EMT");
case SIGFPE: return("FPE");
case SIGKILL: return("KILL");
case SIGBUS: return("BUS");
case SIGSEGV: return("SEGV");
case SIGSYS: return("SYS");
case SIGPIPE: return("PIPE");
case SIGALRM: return("ALRM");
case SIGTERM: return("TERM");
case SIGURG: return("URG");
case SIGSTOP: return("STOP");
case SIGTSTP: return("TSTP");
case SIGCONT: return("CONT");
case SIGCHLD: return("CHLD");
case SIGTTIN: return("TTIN");
case SIGTTOU: return("TTOU");
case SIGIO: return("IO");
case SIGXCPU: return("XCPU");
case SIGXFSZ: return("XFSZ");
case SIGVTALRM: return("VTALRM");
case SIGPROF: return("PROF");
case SIGWINCH: return("WINCH");
#ifdef SIGLOST
case SIGLOST: return("LOST");
#endif
case SIGUSR1: return("USR1");
case SIGUSR2: return("USR2");
}
(void)snprintf(buf, sizeof(buf), "sig %d", s);
return(buf);
}
void
hup_handler(s)
int s;
{
char logoutfile[MAXPATHLEN];
(void) close(0);
seteuid(0);
(void)snprintf(logoutfile, sizeof(logoutfile), "%s.%s",
_PATH_SLIP_LOGOUT, loginname);
if (access(logoutfile, R_OK|X_OK) != 0) {
(void)strncpy(logoutfile, _PATH_SLIP_LOGOUT,
sizeof(logoutfile) - 1);
logoutfile[sizeof(logoutfile) - 1] = '\0';
}
if (access(logoutfile, R_OK|X_OK) == 0) {
char logincmd[2*MAXPATHLEN+32];
(void) snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", logoutfile, unit, speed, loginargs);
(void) system(logincmd);
}
syslog(LOG_INFO, "closed %s slip unit %d (%s)\n", loginname, unit,
sigstr(s));
if (unlink(pidfilename) < 0 && errno != ENOENT)
syslog(LOG_WARNING, "unable to delete pid file: %m");
if (unlink(iffilename) < 0 && errno != ENOENT)
syslog(LOG_WARNING, "unable to delete if file: %m");
exit(1);
/* NOTREACHED */
}
/* Modify the slip line mode and add any compression or no-icmp flags. */
void line_flags(unit)
int unit;
{
struct ifreq ifr;
int s;
/* open a socket as the handle to the interface */
s = socket(AF_INET, SOCK_DGRAM, 0);
if (s < 0) {
syslog(LOG_ERR, "socket: %m");
exit(1);
}
sprintf(ifr.ifr_name, "sl%d", unit);
/* get the flags for the interface */
if (ioctl(s, SIOCGIFFLAGS, (caddr_t)&ifr) < 0) {
syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m");
exit(1);
}
/* Assert any compression or no-icmp flags. */
#define SLMASK (~(IFF_LINK0 | IFF_LINK1 | IFF_LINK2))
ifr.ifr_flags &= SLMASK;
ifr.ifr_flags |= slip_mode;
if (ioctl(s, SIOCSIFFLAGS, (caddr_t)&ifr) < 0) {
syslog(LOG_ERR, "ioctl (SIOCSIFFLAGS): %m");
exit(1);
}
close(s);
}
int
main(argc, argv)
int argc;
char *argv[];
{
int fd, s, ldisc;
char *name;
struct termios tios, otios;
char logincmd[2*BUFSIZ+32];
extern uid_t getuid();
FILE *pidfile; /* pid file */
FILE *iffile; /* interfaces file */
char *p;
int n;
char devnam[MAXPATHLEN] = _PATH_TTY; /* Device name */
if ((name = strrchr(argv[0], '/')) == NULL)
name = argv[0];
s = getdtablesize();
for (fd = 3 ; fd < s ; fd++)
(void) close(fd);
openlog(name, LOG_PID|LOG_PERROR, 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.
*/
if (daemon(1, 1)) {
syslog(LOG_ERR, "daemon(1, 1): %m");
exit(1);
}
if (argc > 2) {
if ((fd = open(argv[2], O_RDWR)) == -1) {
syslog(LOG_ERR, "open %s: %m", argv[2]);
exit(2);
}
(void) dup2(fd, 0);
if (fd > 2)
close(fd);
}
if (ioctl(0, TIOCSCTTY, 0) == -1) {
syslog(LOG_ERR, "ioctl (TIOCSCTTY): %m");
exit(1);
}
if (tcsetpgrp(0, getpid()) < 0) {
syslog(LOG_ERR, "tcsetpgrp failed: %m");
exit(1);
}
} else {
if ((name = getlogin()) == NULL) {
syslog(LOG_ERR, "access denied - login name not found\n");
exit(1);
}
findid(name);
}
(void) fchmod(0, 0600);
(void) fprintf(stderr, "starting slip login for %s\n", loginname);
(void) fprintf(stderr, "your address is %s\n\n", make_ipaddr());
(void) fflush(stderr);
sleep(1);
/* set up the line parameters */
if (tcgetattr(0, &tios) < 0) {
syslog(LOG_ERR, "tcgetattr: %m");
exit(1);
}
otios = tios;
cfmakeraw(&tios);
if (tcsetattr(0, TCSAFLUSH, &tios) < 0) {
syslog(LOG_ERR, "tcsetattr: %m");
exit(1);
}
speed = cfgetispeed(&tios);
ldisc = SLIPDISC;
if (ioctl(0, TIOCSETD, &ldisc) < 0) {
syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
exit(1);
}
if (slunit >= 0 && ioctl(0, SLIOCSUNIT, &slunit) < 0) {
syslog(LOG_ERR, "ioctl (SLIOCSUNIT): %m");
exit(1);
}
/* find out what unit number we were assigned */
if (ioctl(0, SLIOCGUNIT, &unit) < 0) {
syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m");
exit(1);
}
(void) signal(SIGHUP, hup_handler);
(void) signal(SIGTERM, hup_handler);
if (keepal > 0) {
(void) signal(SIGURG, hup_handler);
if (ioctl(0, SLIOCSKEEPAL, &keepal) < 0) {
syslog(LOG_ERR, "ioctl(SLIOCSKEEPAL): %m");
exit(1);
}
}
if (outfill > 0 && ioctl(0, SLIOCSOUTFILL, &outfill) < 0) {
syslog(LOG_ERR, "ioctl(SLIOCSOUTFILL): %m");
exit(1);
}
/* write pid to file */
pid = getpid();
(void) sprintf(ifname, "sl%d", unit);
(void) sprintf(pidfilename, "%s%s.pid", _PATH_VARRUN, ifname);
if ((pidfile = fopen(pidfilename, "w")) != NULL) {
fprintf(pidfile, "%d\n", pid);
(void) fclose(pidfile);
} else {
syslog(LOG_ERR, "Failed to create pid file %s: %m",
pidfilename);
pidfilename[0] = 0;
}
/* write interface unit number to file */
p = ttyname(0);
if (p)
strcpy(devnam, p);
for (n = strlen(devnam); n > 0; n--)
if (devnam[n] == '/') {
n++;
break;
}
(void) sprintf(iffilename, "%s%s.if", _PATH_VARRUN, &devnam[n]);
if ((iffile = fopen(iffilename, "w")) != NULL) {
fprintf(iffile, "sl%d\n", unit);
(void) fclose(iffile);
} else {
syslog(LOG_ERR, "Failed to create if file %s: %m", iffilename);
iffilename[0] = 0;
}
syslog(LOG_INFO, "attaching slip unit %d for %s\n", unit, loginname);
(void)snprintf(logincmd, sizeof(logincmd), "%s %d %ld %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 %s: %m", _PATH_DEVNULL);
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);
exit(6);
}
/* Handle any compression or no-icmp flags. */
line_flags(unit);
/* reset uid to users' to allow the user to give a signal. */
seteuid(uid);
/* twiddle thumbs until we get a signal */
while (1)
sigpause(0);
/* NOTREACHED */
}