| 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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