1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Mini sulogin implementation for busybox
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4 | *
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5 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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6 | */
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7 |
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8 | //usage:#define sulogin_trivial_usage
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9 | //usage: "[-t N] [TTY]"
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10 | //usage:#define sulogin_full_usage "\n\n"
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11 | //usage: "Single user login\n"
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12 | //usage: "\n -t N Timeout"
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13 |
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14 | #include "libbb.h"
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15 | #include <syslog.h>
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16 |
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17 | //static void catchalarm(int UNUSED_PARAM junk)
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18 | //{
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19 | // exit(EXIT_FAILURE);
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20 | //}
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21 |
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22 |
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23 | int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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24 | int sulogin_main(int argc UNUSED_PARAM, char **argv)
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25 | {
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26 | char *cp;
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27 | int timeout = 0;
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28 | struct passwd *pwd;
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29 | const char *shell;
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30 | #if ENABLE_FEATURE_SHADOWPASSWDS
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31 | /* Using _r function to avoid pulling in static buffers */
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32 | char buffer[256];
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33 | struct spwd spw;
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34 | #endif
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35 |
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36 | logmode = LOGMODE_BOTH;
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37 | openlog(applet_name, 0, LOG_AUTH);
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38 |
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39 | opt_complementary = "t+"; /* -t N */
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40 | getopt32(argv, "t:", &timeout);
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41 | argv += optind;
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42 |
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43 | if (argv[0]) {
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44 | close(0);
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45 | close(1);
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46 | dup(xopen(argv[0], O_RDWR));
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47 | close(2);
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48 | dup(0);
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49 | }
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50 |
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51 | /* Malicious use like "sulogin /dev/sda"? */
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52 | if (!isatty(0) || !isatty(1) || !isatty(2)) {
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53 | logmode = LOGMODE_SYSLOG;
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54 | bb_error_msg_and_die("not a tty");
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55 | }
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56 |
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57 | /* Clear dangerous stuff, set PATH */
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58 | sanitize_env_if_suid();
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59 |
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60 | pwd = getpwuid(0);
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61 | if (!pwd) {
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62 | goto auth_error;
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63 | }
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64 |
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65 | #if ENABLE_FEATURE_SHADOWPASSWDS
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66 | {
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67 | /* getspnam_r may return 0 yet set result to NULL.
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68 | * At least glibc 2.4 does this. Be extra paranoid here. */
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69 | struct spwd *result = NULL;
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70 | int r = getspnam_r(pwd->pw_name, &spw, buffer, sizeof(buffer), &result);
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71 | if (r || !result) {
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72 | goto auth_error;
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73 | }
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74 | pwd->pw_passwd = result->sp_pwdp;
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75 | }
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76 | #endif
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77 |
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78 | while (1) {
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79 | char *encrypted;
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80 | int r;
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81 |
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82 | /* cp points to a static buffer that is zeroed every time */
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83 | cp = bb_ask(STDIN_FILENO, timeout,
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84 | "Give root password for system maintenance\n"
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85 | "(or type Control-D for normal startup):");
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86 |
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87 | if (!cp || !*cp) {
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88 | bb_info_msg("Normal startup");
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89 | return 0;
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90 | }
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91 | encrypted = pw_encrypt(cp, pwd->pw_passwd, 1);
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92 | r = strcmp(encrypted, pwd->pw_passwd);
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93 | free(encrypted);
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94 | if (r == 0) {
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95 | break;
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96 | }
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97 | bb_do_delay(LOGIN_FAIL_DELAY);
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98 | bb_info_msg("Login incorrect");
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99 | }
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100 | memset(cp, 0, strlen(cp));
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101 | // signal(SIGALRM, SIG_DFL);
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102 |
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103 | bb_info_msg("System Maintenance Mode");
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104 |
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105 | IF_SELINUX(renew_current_security_context());
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106 |
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107 | shell = getenv("SUSHELL");
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108 | if (!shell)
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109 | shell = getenv("sushell");
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110 | if (!shell)
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111 | shell = pwd->pw_shell;
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112 |
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113 | /* Exec login shell with no additional parameters. Never returns. */
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114 | run_shell(shell, 1, NULL, NULL);
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115 |
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116 | auth_error:
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117 | bb_error_msg_and_die("no password entry for root");
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118 | }
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