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/* sulogin.c - Single User Login.
*
* Copyright 2014 Ashish Kumar Gupta <ashishkguptaiit.cse@gmail.com>
* Copyright 2014 Kyungwan Han <asura321@gmail.com>
*
*
* Relies on libcrypt for hash calculation.
* No support for PAM/securetty/selinux/login script/issue/utmp
USE_SULOGIN(NEWTOY(sulogin, "t#<0=0", TOYFLAG_SBIN|TOYFLAG_NEEDROOT))
config SULOGIN
bool "sulogin"
default n
help
usage: sulogin [-t time] [tty]
Single User Login.
-t Default Time for Single User Login
*/
#define FOR_sulogin
#include "toys.h"
GLOBALS(
long timeout;
struct termios crntio;
)
static void timeout_handle(int signo)
{
tcsetattr(0, TCSANOW, &(TT.crntio));
fflush(stdout);
xprintf("\n Timed out - Normal startup\n");
exit(0);
}
static int validate_password(char *pwd)
{
struct sigaction sa;
int ret;
char *s = "Give root password for system maintenance\n"
"(or type Control-D for normal startup):",
*pass;
tcgetattr(0, &(TT.crntio));
sa.sa_handler = timeout_handle;
if(TT.timeout) {
sigaction(SIGALRM, &sa, NULL);
alarm(TT.timeout);
}
ret = read_password(toybuf, sizeof(toybuf), s);
if(TT.timeout) alarm(0);
if ( ret && !toybuf[0]) {
xprintf("Normal startup.\n");
return -1;
}
pass = crypt(toybuf, pwd);
ret = 1;
if( pass && !strcmp(pass, pwd)) ret = 0;
return ret;
}
static void run_shell(char *shell)
{
snprintf(toybuf,sizeof(toybuf), "-%s", shell);
execl(shell, toybuf, NULL);
error_exit("Failed to spawn shell");
}
void sulogin_main(void)
{
struct passwd *pwd = NULL;
struct spwd * spwd = NULL;
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", NULL
};
char *shell = NULL, *pass = NULL, **temp = forbid;
if (toys.optargs[0]) {
int fd;
dup2((fd = xopen(toys.optargs[0], O_RDWR)), 0);
if (!isatty(0)) error_exit("%s: it is not a tty", toys.optargs[0]);
dup2( fd, 1);
dup2( fd, 2);
if (fd > 2) close(fd);
}
for (temp = forbid; *temp; temp++) unsetenv(*temp);
if (!(pwd = getpwuid(0))) error_exit("invalid user");
pass = pwd->pw_passwd;
if ((pass[0] == 'x' || pass[0] == '*') && !pass[1]) {
if ((spwd = getspnam (pwd->pw_name))) pass = spwd->sp_pwdp;
}
while (1) {
int r = validate_password(pass);
if (r == 1) xprintf("Incorrect Login.\n");
else if (r == 0) break;
else if (r == -1) return;
}
if ((shell = getenv("SUSHELL")) || (shell = getenv("sushell"))
|| (shell = pwd->pw_shell))
run_shell((shell && *shell)? shell: "/bin/sh");
}
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