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/* login.c - Start a session on the system.
*
* Copyright 2012 Elie De Brauwer <eliedebrauwer@gmail.com>
*
* No support for PAM/securetty/selinux/login script/issue/utmp
* Relies on libcrypt for hash calculation.
*
* TODO: this command predates "pending" but needs cleanup. It #defines
* random stuff, calls exit() form a signal handler... yeah.
USE_LOGIN(NEWTOY(login, ">1f:ph:", TOYFLAG_BIN|TOYFLAG_NEEDROOT))
config LOGIN
bool "login"
default y
depends on TOYBOX_SHADOW
help
usage: login [-p] [-h host] [-f USERNAME] [USERNAME]
Log in as a user, prompting for username and password if necessary.
-p Preserve environment
-h The name of the remote host for this login
-f login as USERNAME without authentication
*/
#define FOR_login
#include "toys.h"
GLOBALS(
char *h, *f;
int login_timeout, login_fail_timeout;
)
static void login_timeout_handler(int sig __attribute__((unused)))
{
printf("\nLogin timed out after %d seconds.\n", TT.login_timeout);
exit(0);
}
void login_main(void)
{
char *forbid[] = {
"BASH_ENV", "ENV", "HOME", "IFS", "LD_LIBRARY_PATH", "LD_PRELOAD",
"LD_TRACE_LOADED_OBJECTS", "LD_BIND_NOW", "LD_AOUT_LIBRARY_PATH",
"LD_AOUT_PRELOAD", "LD_NOWARN", "LD_KEEPDIR", "SHELL"
};
int hh = FLAG(h), count, tty;
char uu[33], *username, *pass = 0, *ss;
struct passwd *pwd = 0;
for (tty=0; tty<3; tty++) if (isatty(tty)) break;
if (tty == 3) error_exit("no tty");
for (count = 0; count < ARRAY_LEN(forbid); count++) unsetenv(forbid[count]);
openlog("login", LOG_PID | LOG_CONS, LOG_AUTH);
xsignal(SIGALRM, login_timeout_handler);
if (TT.f) username = TT.f;
else username = *toys.optargs;
for (count = 0; count < 3; count++) {
alarm(TT.login_timeout = 60);
tcflush(0, TCIFLUSH);
if (!username) {
int i;
memset(username = uu, 0, sizeof(uu));
gethostname(uu, sizeof(uu)-1);
printf("%s%slogin: ", *uu ? uu : "", *uu ? " " : "");
fflush(stdout);
if(!fgets(uu, sizeof(uu)-1, stdin)) _exit(1);
// Remove trailing \n and so on
for (i = 0; i<sizeof(uu); i++) if (uu[i]<=' ' || uu[i]==':') uu[i]=0;
if (!*uu) {
username = 0;
continue;
}
}
// If user exists and isn't locked
pwd = getpwnam(username);
if (pwd && *pwd->pw_passwd != '!' && *pwd->pw_passwd != '*') {
// Pre-authenticated or passwordless
if (TT.f || !*pwd->pw_passwd) break;
// fetch shadow password if necessary
if (*(pass = pwd->pw_passwd) == 'x') {
struct spwd *spwd = getspnam (username);
if (spwd) pass = spwd->sp_pwdp;
}
} else if (TT.f) error_exit("bad -f '%s'", TT.f);
// Verify password. (Prompt for password _before_ checking disable state.)
if (!read_password(toybuf, sizeof(toybuf), "Password: ")) {
int x = pass && (ss = crypt(toybuf, pass)) && !strcmp(pass, ss);
// password go bye-bye now.
memset(toybuf, 0, sizeof(toybuf));
if (x) break;
}
syslog(LOG_WARNING, "invalid password for '%s' on %s %s%s", pwd->pw_name,
ttyname(tty), hh ? "from " : "", hh ? TT.h : "");
sleep(3);
puts("Login incorrect");
username = 0;
pwd = 0;
}
alarm(0);
// This had password data in it, and we reuse for motd below
memset(toybuf, 0, sizeof(toybuf));
if (!pwd) error_exit("max retries (3)");
// Check twice because "this file exists" is a security test, and in
// theory filehandle exhaustion or other error could make open/read fail.
if (pwd->pw_uid && !access("/etc/nologin", R_OK)) {
ss = readfile("/etc/nologin", toybuf, sizeof(toybuf));
puts ((ss && *ss) ? ss : "nologin");
free(ss);
toys.exitval = 1;
return;
}
if (fchown(tty, pwd->pw_uid, pwd->pw_gid) || fchmod(tty, 0600))
printf("can't claim tty");
xsetuser(pwd);
if (chdir(pwd->pw_dir)) printf("bad $HOME: %s\n", pwd->pw_dir);
if (!FLAG(p)) {
char *term = getenv("TERM");
clearenv();
if (term) setenv("TERM", term, 1);
}
setenv("USER", pwd->pw_name, 1);
setenv("LOGNAME", pwd->pw_name, 1);
setenv("HOME", pwd->pw_dir, 1);
setenv("SHELL", pwd->pw_shell, 1);
// Message of the day
if ((ss = readfile("/etc/motd", 0, 0))) {
puts(ss);
free(ss);
}
syslog(LOG_INFO, "%s logged in on %s %s %s", pwd->pw_name,
ttyname(tty), hh ? "from" : "", hh ? TT.h : "");
// not using xexec(), login calls absolute path from filesystem so must exec()
execl(pwd->pw_shell, xmprintf("-%s", pwd->pw_shell), (char *)0);
perror_exit("exec shell '%s'", pwd->pw_shell);
}
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