1 /* vi: set sw=4 ts=4: */
3 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
7 #include <sys/resource.h>
10 # include <selinux/selinux.h> /* for is_selinux_enabled() */
11 # include <selinux/get_context_list.h> /* for get_default_context() */
12 # include <selinux/flask.h> /* for security class definitions */
16 /* PAM may include <locale.h>. We may need to undefine bbox's stub define: */
18 /* For some obscure reason, PAM is not in pam/xxx, but in security/xxx.
19 * Apparently they like to confuse people. */
20 # include <security/pam_appl.h>
21 # include <security/pam_misc.h>
22 static const struct pam_conv conv = {
30 EMPTY_USERNAME_COUNT = 10,
35 static char* short_tty;
37 #if ENABLE_FEATURE_NOLOGIN
38 static void die_if_nologin(void)
44 fp = fopen_for_read("/etc/nologin");
45 if (!fp) /* assuming it does not exist */
48 while ((c = getc(fp)) != EOF) {
55 puts("\r\nSystem closed for routine maintenance\r");
59 /* Users say that they do need this prior to exit: */
60 tcdrain(STDOUT_FILENO);
64 # define die_if_nologin() ((void)0)
67 #if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM
68 static int check_securetty(void)
70 char *buf = (char*)"/etc/securetty"; /* any non-NULL is ok */
71 parser_t *parser = config_open2("/etc/securetty", fopen_for_read);
72 while (config_read(parser, &buf, 1, 1, "# \t", PARSE_NORMAL)) {
73 if (strcmp(buf, short_tty) == 0)
78 /* buf != NULL here if config file was not found, empty
79 * or line was found which equals short_tty */
83 static ALWAYS_INLINE int check_securetty(void) { return 1; }
87 static void initselinux(char *username, char *full_tty,
88 security_context_t *user_sid)
90 security_context_t old_tty_sid, new_tty_sid;
92 if (!is_selinux_enabled())
95 if (get_default_context(username, NULL, user_sid)) {
96 bb_error_msg_and_die("can't get SID for %s", username);
98 if (getfilecon(full_tty, &old_tty_sid) < 0) {
99 bb_perror_msg_and_die("getfilecon(%s) failed", full_tty);
101 if (security_compute_relabel(*user_sid, old_tty_sid,
102 SECCLASS_CHR_FILE, &new_tty_sid) != 0) {
103 bb_perror_msg_and_die("security_change_sid(%s) failed", full_tty);
105 if (setfilecon(full_tty, new_tty_sid) != 0) {
106 bb_perror_msg_and_die("chsid(%s, %s) failed", full_tty, new_tty_sid);
111 #if ENABLE_LOGIN_SCRIPTS
112 static void run_login_script(struct passwd *pw, char *full_tty)
116 t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT");
119 xsetenv("LOGIN_TTY", full_tty);
120 xsetenv("LOGIN_USER", pw->pw_name);
121 xsetenv("LOGIN_UID", utoa(pw->pw_uid));
122 xsetenv("LOGIN_GID", utoa(pw->pw_gid));
123 xsetenv("LOGIN_SHELL", pw->pw_shell);
124 spawn_and_wait(t_argv); /* NOMMU-friendly */
125 unsetenv("LOGIN_TTY");
126 unsetenv("LOGIN_USER");
127 unsetenv("LOGIN_UID");
128 unsetenv("LOGIN_GID");
129 unsetenv("LOGIN_SHELL");
133 void run_login_script(struct passwd *pw, char *full_tty);
136 static void get_username_or_die(char *buf, int size_buf)
140 cntdown = EMPTY_USERNAME_COUNT;
142 print_login_prompt();
143 /* skip whitespace */
153 } while (isspace(c)); /* maybe isblank? */
156 if (!fgets(buf, size_buf-2, stdin))
158 if (!strchr(buf, '\n'))
160 while ((unsigned char)*buf > ' ')
165 static void motd(void)
169 fd = open(bb_path_motd_file, O_RDONLY);
172 bb_copyfd_eof(fd, STDOUT_FILENO);
177 static void alarm_handler(int sig UNUSED_PARAM)
179 /* This is the escape hatch! Poor serial line users and the like
180 * arrive here when their connection is broken.
181 * We don't want to block here */
183 printf("\r\nLogin timed out after %d seconds\r\n", TIMEOUT);
185 /* unix API is brain damaged regarding O_NONBLOCK,
186 * we should undo it, or else we can affect other processes */
191 int login_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
192 int login_main(int argc UNUSED_PARAM, char **argv)
195 LOGIN_OPT_f = (1<<0),
196 LOGIN_OPT_h = (1<<1),
197 LOGIN_OPT_p = (1<<2),
200 char username[USERNAME_SIZE];
205 char *opt_host = NULL;
206 char *opt_user = opt_user; /* for compiler */
208 IF_SELINUX(security_context_t user_sid = NULL;)
213 const char *failed_msg;
214 struct passwd pwdstruct;
220 signal(SIGALRM, alarm_handler);
223 /* More of suid paranoia if called by non-root: */
224 /* Clear dangerous stuff, set PATH */
225 run_by_root = !sanitize_env_if_suid();
227 /* Mandatory paranoia for suid applet:
228 * ensure that fd# 0,1,2 are opened (at least to /dev/null)
229 * and any extra open fd's are closed.
230 * (The name of the function is misleading. Not daemonizing here.) */
231 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL);
233 opt = getopt32(argv, "f:h:p", &opt_user, &opt_host);
234 if (opt & LOGIN_OPT_f) {
236 bb_error_msg_and_die("-f is for root only");
237 safe_strncpy(username, opt_user, sizeof(username));
240 if (argv[0]) /* user from command line (getty) */
241 safe_strncpy(username, argv[0], sizeof(username));
243 /* Let's find out and memorize our tty */
244 if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO) || !isatty(STDERR_FILENO))
245 return EXIT_FAILURE; /* Must be a terminal */
246 full_tty = xmalloc_ttyname(STDIN_FILENO);
248 full_tty = xstrdup("UNKNOWN");
249 short_tty = skip_dev_pfx(full_tty);
252 fromhost = xasprintf(" on '%s' from '%s'", short_tty, opt_host);
254 fromhost = xasprintf(" on '%s'", short_tty);
257 /* Was breaking "login <username>" from shell command line: */
260 openlog(applet_name, LOG_PID | LOG_CONS, LOG_AUTH);
263 /* flush away any type-ahead (as getty does) */
264 tcflush(0, TCIFLUSH);
267 get_username_or_die(username, sizeof(username));
270 pamret = pam_start("login", username, &conv, &pamh);
271 if (pamret != PAM_SUCCESS) {
272 failed_msg = "start";
273 goto pam_auth_failed;
275 /* set TTY (so things like securetty work) */
276 pamret = pam_set_item(pamh, PAM_TTY, short_tty);
277 if (pamret != PAM_SUCCESS) {
278 failed_msg = "set_item(TTY)";
279 goto pam_auth_failed;
281 pamret = pam_authenticate(pamh, 0);
282 if (pamret != PAM_SUCCESS) {
283 failed_msg = "authenticate";
284 goto pam_auth_failed;
285 /* TODO: or just "goto auth_failed"
286 * since user seems to enter wrong password
287 * (in this case pamret == 7)
290 /* check that the account is healthy */
291 pamret = pam_acct_mgmt(pamh, 0);
292 if (pamret != PAM_SUCCESS) {
293 failed_msg = "acct_mgmt";
294 goto pam_auth_failed;
298 /* gcc: "dereferencing type-punned pointer breaks aliasing rules..."
299 * thus we cast to (void*) */
300 if (pam_get_item(pamh, PAM_USER, (void*)&pamuser) != PAM_SUCCESS) {
301 failed_msg = "get_item(USER)";
302 goto pam_auth_failed;
304 if (!pamuser || !pamuser[0])
306 safe_strncpy(username, pamuser, sizeof(username));
307 /* Don't use "pw = getpwnam(username);",
308 * PAM is said to be capable of destroying static storage
309 * used by getpwnam(). We are using safe(r) function */
311 getpwnam_r(username, &pwdstruct, pwdbuf, sizeof(pwdbuf), &pw);
314 pamret = pam_open_session(pamh, 0);
315 if (pamret != PAM_SUCCESS) {
316 failed_msg = "open_session";
317 goto pam_auth_failed;
319 pamret = pam_setcred(pamh, PAM_ESTABLISH_CRED);
320 if (pamret != PAM_SUCCESS) {
321 failed_msg = "setcred";
322 goto pam_auth_failed;
324 break; /* success, continue login process */
327 /* syslog, because we don't want potential attacker
328 * to know _why_ login failed */
329 syslog(LOG_WARNING, "pam_%s call failed: %s (%d)", failed_msg,
330 pam_strerror(pamh, pamret), pamret);
331 safe_strncpy(username, "UNKNOWN", sizeof(username));
333 pw = getpwnam(username);
335 strcpy(username, "UNKNOWN");
339 if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*')
342 if (opt & LOGIN_OPT_f)
343 break; /* -f USER: success without asking passwd */
345 if (pw->pw_uid == 0 && !check_securetty())
348 /* Don't check the password if password entry is empty (!) */
349 if (!pw->pw_passwd[0])
352 /* authorization takes place here */
353 if (correct_password(pw))
355 #endif /* ENABLE_PAM */
358 bb_do_delay(LOGIN_FAIL_DELAY);
359 /* TODO: doesn't sound like correct English phrase to me */
360 puts("Login incorrect");
362 syslog(LOG_WARNING, "invalid password for '%s'%s",
365 if (ENABLE_FEATURE_CLEAN_UP)
374 /* We can ignore /etc/nologin if we are logging in as root,
375 * it doesn't matter whether we are run by root or not */
379 IF_SELINUX(initselinux(username, full_tty, &user_sid));
381 /* Try these, but don't complain if they fail.
382 * _f_chown is safe wrt race t=ttyname(0);...;chown(t); */
383 fchown(0, pw->pw_uid, pw->pw_gid);
386 update_utmp(getpid(), USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL);
388 /* We trust environment only if we run by root */
389 if (ENABLE_LOGIN_SCRIPTS && run_by_root)
390 run_login_script(pw, full_tty);
393 setup_environment(pw->pw_shell,
394 (!(opt & LOGIN_OPT_p) * SETUP_ENV_CLEARENV) + SETUP_ENV_CHANGEENV,
398 /* Modules such as pam_env will setup the PAM environment,
399 * which should be copied into the new environment. */
400 pamenv = pam_getenvlist(pamh);
401 if (pamenv) while (*pamenv) {
410 syslog(LOG_INFO, "root login%s", fromhost);
412 if (ENABLE_FEATURE_CLEAN_UP)
415 /* well, a simple setexeccon() here would do the job as well,
416 * but let's play the game for now */
417 IF_SELINUX(set_current_security_context(user_sid);)
419 // util-linux login also does:
420 // /* start new session */
422 // /* TIOCSCTTY: steal tty from other process group */
423 // if (ioctl(0, TIOCSCTTY, 1)) error_msg...
424 // BBox login used to do this (see above):
426 // If this stuff is really needed, add it and explain why!
428 /* Set signals to defaults */
429 /* Non-ignored signals revert to SIG_DFL on exec anyway */
430 /*signal(SIGALRM, SIG_DFL);*/
432 /* Is this correct? This way user can ctrl-c out of /etc/profile,
433 * potentially creating security breach (tested with bash 3.0).
434 * But without this, bash 3.0 will not enable ctrl-c either.
435 * Maybe bash is buggy?
436 * Need to find out what standards say about /bin/login -
437 * should we leave SIGINT etc enabled or disabled? */
438 signal(SIGINT, SIG_DFL);
440 /* Exec login shell with no additional parameters */
441 run_shell(pw->pw_shell, 1, NULL, NULL);
443 /* return EXIT_FAILURE; - not reached */