Minix1.5/commands/login.c
/* login - log into the system Author: Patric van Kleef */
/* Original version by Patrick van Kleef. History of modifications:
*
* Peter S. Housel Jan. 1988
* - Set up $USER, $HOME and $TERM.
* - Set signals to SIG_DFL.
*
* Terrence W. Holm June 1988
* - Allow a username as an optional argument.
* - Time out if a password is not typed within 30 seconds.
* - Perform a dummy delay after a bad username is entered.
* - Don't allow a login if "/etc/nologin" exists.
* - Cause a failure on bad "pw_shell" fields.
* - Record the login in "/usr/adm/wtmp".
*
* Peter S. Housel Dec. 1988
* - Record the login in "/etc/utmp" also.
*
* F. van Kempen June 1989
* - various patches for Minix V1.4a.
*
* F. van Kempen September 1989
* - added login-failure administration (new utmp.h needed!).
* - support arguments in pw_shell field
* - adapted source text to MINIX Style Sheet
*
* F. van Kempen October 1989
* - adapted to new utmp database.
* F. van Kempen, December 1989
* - fixed 'slot' assumption in wtmp()
* - fixed all MSS-stuff
* - adapted to POSIX (MINIX 1.5)
* F. van Kempen, January 1990
* - made all 'bad login accounting' optional by "#ifdef BADLOG".
* F. van Kempen, Februari 1990
* - fixed 'first argument' bug and added some casts.
*
* Andy Tanenbaum April 1990
* - if /bin/sh cannot be located, try /usr/bin/sh
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sgtty.h>
#include <signal.h>
#include <string.h>
#include <pwd.h>
#include <unistd.h>
#include <utmp.h>
#include <stdio.h>
#define DIGIT 3
#define MOTD "/etc/motd"
#define TTY "tty?"
#define CONS "tty0"
static char *Version = "@(#) LOGIN 1.13 (02/10/90)";
int time_out;
char user[32];
char logname[35];
char home[64];
char shell[64];
char *env[] = {
user,
logname,
home,
shell,
"TERM=minix",
NULL
};
extern char *crypt();
extern struct passwd *getpwnam();
extern long time();
extern long lseek();
void Time_out();
void wtmp(line, user)
char *line; /* tty device name */
char *user; /* user name */
{
/* Make entries in /usr/adm/wtmp and /etc/utmp. */
struct utmp entry, oldent;
char *blank = " ";
register int fd;
register char *sp;
int lineno;
extern long time();
/* Strip off the /dev part of the TTY name. */
sp = strrchr(line, '/');
if (sp == NULL)
sp = line;
else
sp++;
/* First, read the current UTMP entry. we need some of its
* parameters! (like PID, ID etc...). */
if ((fd = open(UTMP, O_RDONLY)) < 0) return;
lineno = 0;
while (read(fd, (char *) &oldent, sizeof(struct utmp))
== sizeof(struct utmp)) {
if (oldent.ut_pid == getpid()) break;
lineno++;
}
lineno *= sizeof(struct utmp);
if (lseek(fd, (long) lineno, SEEK_SET) >= 0) {
read(fd, (char *) &oldent, sizeof(struct utmp));
}
close(fd);
/* Clear out the new string fields. */
strncpy(entry.ut_user, blank, sizeof(entry.ut_user));
strncpy(entry.ut_id, blank, sizeof(entry.ut_id));
strncpy(entry.ut_line, blank, sizeof(entry.ut_line));
/* Enter new string fields. */
strncpy(entry.ut_user, user, sizeof(entry.ut_user));
strncpy(entry.ut_id, oldent.ut_id, sizeof(entry.ut_id));
strncpy(entry.ut_line, sp, sizeof(entry.ut_line));
/* Copy old numeric fields. */
entry.ut_pid = oldent.ut_pid;
/* Change new numeric fields. */
entry.ut_type = USER_PROCESS; /* we are past login... */
time(&(entry.ut_time));
/* Write a WTMP record. */
if ((fd = open(WTMP, O_WRONLY)) > 0) {
if (lseek(fd, 0L, SEEK_END) >= 0L) {
write(fd, (char *) &entry, sizeof(struct utmp));
}
close(fd);
}
/* Rewrite the UTMP entry. */
if ((fd = open(UTMP, O_WRONLY)) > 0) {
if (lseek(fd, (long) lineno, SEEK_SET) >= 0) {
write(fd, (char *) &entry, sizeof(struct utmp));
}
close(fd);
}
}
#ifdef BADLOG
void addlog(nam, pwd, tty)
char *nam; /* name of attempting user */
char *pwd; /* attempted password */
char *tty; /* name of terminal line */
{
/* Register a failed login if the logfile exists. */
struct utmp entry;
int fd;
strncpy(entry.ut_name, nam, sizeof(entry.ut_name));
strncpy(entry.ut_line, tty, sizeof(entry.ut_line));
entry.ut_time = time((time_t *)0);
if ((fd = open(BTMP, O_WRONLY)) < 0) return;
if (lseek(fd, 0L, SEEK_END) >= 0L) {
/* Append the entry to the btmp file. */
write(fd, (char *) &entry, sizeof(struct utmp));
}
close(fd);
}
#endif /* BADLOG */
void show_file(nam)
char *nam;
{
/* Read a textfile and show it on the desired terminal. */
register int fd, len;
char buf[80];
if ((fd = open(nam, O_RDONLY)) > 0) {
len = 1;
while (len > 0) {
len = read(fd, buf, 80);
write(1, buf, len);
}
close(fd);
}
}
int main(argc, argv)
int argc;
char *argv[];
{
char name[30];
char password[30];
char ttyname[16];
int bad, n, ttynr, ap;
struct sgttyb args;
struct passwd *pwd;
struct stat statbuf;
char *bp, *argx[8]; /* pw_shell arguments */
char *sh = "/bin/sh"; /* sh/pw_shell field value */
char *sh2= "/usr/bin/sh"; /* other possibility */
/* Reset some of the line parameters in case they have been mashed. */
if (ioctl(0, TIOCGETP, &args) < 0) exit(1);
#ifdef NOGETTY
args.sg_kill = '\030'; /* CTRL-X */
args.sg_erase = '\b';
args.sg_flags |= (XTABS | CRMOD | ECHO);
ioctl(0, TIOCSETP, &args);
#endif /* NOGETTY */
/* Look up /dev/tty number. */
fstat(0, &statbuf);
ttynr = statbuf.st_rdev & 0377;
if (ttynr == 0)
strcpy(ttyname, CONS); /* system console */
else {
strcpy(ttyname, TTY);
ttyname[DIGIT] = '0' + ttynr;
}
/* Get login name and passwd. */
for (;;) {
bad = 0;
if (argc > 1) {
strcpy(name, argv[1]);
argc = 1;
} else {
do {
write(1, "login: ", 7);
n = read(0, name, 30);
} while (n < 2);
name[n - 1] = 0;
}
/* Look up login/passwd. */
if ((pwd = getpwnam(name)) == (struct passwd *) NULL) bad++;
/* If login name wrong or password exists, ask for pw. */
if (bad || strlen(pwd->pw_passwd) != 0) {
args.sg_flags &= ~ECHO;
ioctl(0, TIOCSETP, &args);
write(1, "Password: ", 10);
time_out = 0;
signal(SIGALRM, Time_out);
alarm(30);
n = read(0, password, 30);
alarm(0);
if (time_out) {
n = 1;
bad++;
}
password[n - 1] = 0;
write(1, "\n", 1);
args.sg_flags |= ECHO;
ioctl(0, TIOCSETP, &args);
if (bad && crypt(password, "aaaa") ||
strcmp(pwd->pw_passwd, crypt(password, pwd->pw_passwd))) {
#ifdef BADLOG
addlog(name, password, ttyname);
#endif /* BADLOG */
write(1, "Login incorrect\n", 16);
continue;
}
}
/* Check if the system is going down */
if (access("/etc/nologin", 0) == 0 && strcmp(name, "root") != 0) {
write(1, "System going down\n\n", 19);
continue;
}
/* Write login record to /usr/adm/wtmp and /etc/utmp */
wtmp(ttyname, name);
/* Create the argv[] array from the pw_shell field. */
ap = 0;
argx[ap++] = "-"; /* most shells need it for their .profile */
if (pwd->pw_shell[0]) {
sh = pwd->pw_shell;
bp = sh;
while (*bp) {
while (*bp && *bp != ' ' && *bp != '\t') bp++;
if (*bp == ' ' || *bp == '\t') {
*bp++ = '\0'; /* mark end of string */
argx[ap++] = bp;
}
}
} else
argx[ap] = (char *) NULL;
/* Set the environment */
strcpy(user, "USER=");
strcat(user, name);
strcpy(logname, "LOGNAME=");
strcat(logname, name);
strcpy(home, "HOME=");
strcat(home, pwd->pw_dir);
strcpy(shell, "SHELL=");
strcat(shell, sh);
chdir(pwd->pw_dir);
/* Reset signals to default values. */
for (n = 1; n <= _NSIG; ++n) signal(n, SIG_DFL);
/* Show the message-of-the-day. */
show_file(MOTD);
/* Assign the terminal to this user. */
strcpy(name, "/dev/");
strcat(name, ttyname);
chown(name, pwd->pw_uid, pwd->pw_gid);
setgid(pwd->pw_gid);
setuid(pwd->pw_uid);
execve(sh, argx, env);
execve(sh2, argx, env); /* if /bin/sh absent, try /usr/bin/sh*/
write(1, "exec failure\n", 13);
exit(1);
}
}
void Time_out()
{
time_out = 1;
}