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
11 USE_SULOGIN(NEWTOY(sulogin, "t#<0=0", TOYFLAG_SBIN|TOYFLAG_NEEDROOT))
12
13 config SULOGIN
14 bool "sulogin"
15 default n
16 help
17 usage: sulogin [-t time] [tty]
18
19 Single User Login.
20 -t Default Time for Single User Login
21 */
22 #define FOR_sulogin
23 #include "toys.h"
24
GLOBALS(long timeout;struct termios crntio;)25 GLOBALS(
26 long timeout;
27 struct termios crntio;
28 )
29
30 static void timeout_handle(int signo)
31 {
32 tcsetattr(0, TCSANOW, &(TT.crntio));
33 fflush(stdout);
34 xprintf("\n Timed out - Normal startup\n");
35 exit(0);
36 }
37
validate_password(char * pwd)38 static int validate_password(char *pwd)
39 {
40 struct sigaction sa;
41 int ret;
42 char *s = "Give root password for system maintenance\n"
43 "(or type Control-D for normal startup):",
44 *pass;
45
46 tcgetattr(0, &(TT.crntio));
47 sa.sa_handler = timeout_handle;
48
49 if(TT.timeout) {
50 sigaction(SIGALRM, &sa, NULL);
51 alarm(TT.timeout);
52 }
53
54 ret = read_password(toybuf, sizeof(toybuf), s);
55 if(TT.timeout) alarm(0);
56
57 if ( ret && !toybuf[0]) {
58 xprintf("Normal startup.\n");
59 return -1;
60 }
61
62 pass = crypt(toybuf, pwd);
63 ret = 1;
64 if( pass && !strcmp(pass, pwd)) ret = 0;
65
66 return ret;
67 }
68
run_shell(char * shell)69 static void run_shell(char *shell)
70 {
71 snprintf(toybuf,sizeof(toybuf), "-%s", shell);
72 execl(shell, toybuf, NULL);
73 error_exit("Failed to spawn shell");
74 }
75
sulogin_main(void)76 void sulogin_main(void)
77 {
78 struct passwd *pwd = NULL;
79 struct spwd * spwd = NULL;
80 char *forbid[] = {
81 "BASH_ENV", "ENV", "HOME", "IFS", "LD_LIBRARY_PATH", "LD_PRELOAD",
82 "LD_TRACE_LOADED_OBJECTS", "LD_BIND_NOW", "LD_AOUT_LIBRARY_PATH",
83 "LD_AOUT_PRELOAD", "LD_NOWARN", "LD_KEEPDIR", "SHELL", NULL
84 };
85 char *shell = NULL, *pass = NULL, **temp = forbid;
86
87 if (toys.optargs[0]) {
88 int fd;
89
90 dup2((fd = xopen_stdio(toys.optargs[0], O_RDWR)), 0);
91 if (!isatty(0)) error_exit("%s: it is not a tty", toys.optargs[0]);
92 dup2( fd, 1);
93 dup2( fd, 2);
94 if (fd > 2) close(fd);
95 }
96
97 for (temp = forbid; *temp; temp++) unsetenv(*temp);
98
99 if (!(pwd = getpwuid(0))) error_exit("invalid user");
100 pass = pwd->pw_passwd;
101
102 if ((pass[0] == 'x' || pass[0] == '*') && !pass[1]) {
103 if ((spwd = getspnam (pwd->pw_name))) pass = spwd->sp_pwdp;
104 }
105
106 while (1) {
107 int r = validate_password(pass);
108
109 if (r == 1) xprintf("Incorrect Login.\n");
110 else if (r == 0) break;
111 else if (r == -1) return;
112 }
113
114 if ((shell = getenv("SUSHELL")) || (shell = getenv("sushell"))
115 || (shell = pwd->pw_shell))
116 run_shell((shell && *shell)? shell: "/bin/sh");
117 }
118