1/* sulogin.c - Single User Login.
2 *
3 * Copyright 2014 Ashish Kumar Gupta <ashishkguptaiit.cse@gmail.com>
4 * Copyright 2014 Kyungwan Han <asura321@gmail.com>
5 *
6 *
7 * Relies on libcrypt for hash calculation.
8 * No support for PAM/securetty/selinux/login script/issue/utmp
9
10
11USE_SULOGIN(NEWTOY(sulogin, "t#<0=0", TOYFLAG_SBIN|TOYFLAG_NEEDROOT))
12
13config SULOGIN
14  bool "sulogin"
15  default n
16  depends on TOYBOX_SHADOW
17  help
18    usage: sulogin [-t time] [tty]
19
20    Single User Login.
21    -t	Default Time for Single User Login
22*/
23#define FOR_sulogin
24#include "toys.h"
25
26GLOBALS(
27  long timeout;
28  struct termios crntio;
29)
30
31static void timeout_handle(int signo)
32{
33  tcsetattr(0, TCSANOW, &(TT.crntio));
34  fflush(stdout);
35  xprintf("\n Timed out - Normal startup\n");
36  exit(0);
37}
38
39static int validate_password(char *pwd)
40{
41  struct sigaction sa;
42  int ret;
43  char *s = "Give root password for system maintenance\n"
44    "(or type Control-D for normal startup):",
45    *pass;
46
47  tcgetattr(0, &(TT.crntio));
48  sa.sa_handler = timeout_handle;
49
50  if(TT.timeout) {
51    sigaction(SIGALRM, &sa, NULL);
52    alarm(TT.timeout);
53  }
54
55  ret = read_password(toybuf, sizeof(toybuf), s);
56  if(TT.timeout) alarm(0);
57
58  if ( ret && !toybuf[0]) {
59    xprintf("Normal startup.\n");
60    return -1;
61  }
62
63  pass = crypt(toybuf, pwd);
64  ret = 1;
65  if( pass && !strcmp(pass, pwd)) ret = 0;
66
67  return ret;
68}
69
70static void run_shell(char *shell)
71{
72  snprintf(toybuf,sizeof(toybuf), "-%s", shell);
73  execl(shell, toybuf, NULL);
74  error_exit("Failed to spawn shell");
75}
76
77void sulogin_main(void)
78{
79  struct passwd *pwd = NULL;
80  struct spwd * spwd = NULL;
81  char *forbid[] = {
82    "BASH_ENV", "ENV", "HOME", "IFS", "LD_LIBRARY_PATH", "LD_PRELOAD",
83    "LD_TRACE_LOADED_OBJECTS", "LD_BIND_NOW", "LD_AOUT_LIBRARY_PATH",
84    "LD_AOUT_PRELOAD", "LD_NOWARN", "LD_KEEPDIR", "SHELL", NULL
85  };
86  char *shell = NULL, *pass = NULL, **temp = forbid;
87
88  if (toys.optargs[0]) {
89    int fd;
90
91    dup2((fd = xopen_stdio(toys.optargs[0], O_RDWR)), 0);
92    if (!isatty(0)) error_exit("%s: it is not a tty", toys.optargs[0]);
93    dup2( fd, 1);
94    dup2( fd, 2);
95    if (fd > 2) close(fd);
96  }
97
98  for (temp = forbid; *temp; temp++) unsetenv(*temp);
99
100  if (!(pwd = getpwuid(0))) error_exit("invalid user");
101  pass = pwd->pw_passwd;
102
103  if ((pass[0] == 'x' || pass[0] == '*') && !pass[1]) {
104    if ((spwd = getspnam (pwd->pw_name))) pass = spwd->sp_pwdp;
105  }
106
107  while (1) {
108    int r = validate_password(pass);
109
110    if (r == 1) xprintf("Incorrect Login.\n");
111    else if (r == 0) break;
112    else if (r == -1) return;
113  }
114
115  if ((shell = getenv("SUSHELL")) || (shell = getenv("sushell"))
116      || (shell = pwd->pw_shell))
117    run_shell((shell && *shell)? shell: "/bin/sh");
118}
119