Contents of /trunk/mkinitrd-magellan/busybox/loginutils/login.c
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Wed Aug 18 21:56:57 2010 UTC (14 years, 1 month ago) by niro
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File size: 11620 byte(s)
Wed Aug 18 21:56:57 2010 UTC (14 years, 1 month ago) by niro
File MIME type: text/plain
File size: 11620 byte(s)
-updated to busybox-1.17.1
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
4 | */ |
5 | #include "libbb.h" |
6 | #include <syslog.h> |
7 | #if ENABLE_FEATURE_UTMP |
8 | # include <utmp.h> /* USER_PROCESS */ |
9 | #endif |
10 | #include <sys/resource.h> |
11 | |
12 | #if ENABLE_SELINUX |
13 | # include <selinux/selinux.h> /* for is_selinux_enabled() */ |
14 | # include <selinux/get_context_list.h> /* for get_default_context() */ |
15 | # include <selinux/flask.h> /* for security class definitions */ |
16 | #endif |
17 | |
18 | #if ENABLE_PAM |
19 | /* PAM may include <locale.h>. We may need to undefine bbox's stub define: */ |
20 | # undef setlocale |
21 | /* For some obscure reason, PAM is not in pam/xxx, but in security/xxx. |
22 | * Apparently they like to confuse people. */ |
23 | # include <security/pam_appl.h> |
24 | # include <security/pam_misc.h> |
25 | static const struct pam_conv conv = { |
26 | misc_conv, |
27 | NULL |
28 | }; |
29 | #endif |
30 | |
31 | enum { |
32 | TIMEOUT = 60, |
33 | EMPTY_USERNAME_COUNT = 10, |
34 | USERNAME_SIZE = 32, |
35 | TTYNAME_SIZE = 32, |
36 | }; |
37 | |
38 | static char* short_tty; |
39 | |
40 | #if ENABLE_FEATURE_NOLOGIN |
41 | static void die_if_nologin(void) |
42 | { |
43 | FILE *fp; |
44 | int c; |
45 | int empty = 1; |
46 | |
47 | fp = fopen_for_read("/etc/nologin"); |
48 | if (!fp) /* assuming it does not exist */ |
49 | return; |
50 | |
51 | while ((c = getc(fp)) != EOF) { |
52 | if (c == '\n') |
53 | bb_putchar('\r'); |
54 | bb_putchar(c); |
55 | empty = 0; |
56 | } |
57 | if (empty) |
58 | puts("\r\nSystem closed for routine maintenance\r"); |
59 | |
60 | fclose(fp); |
61 | fflush_all(); |
62 | /* Users say that they do need this prior to exit: */ |
63 | tcdrain(STDOUT_FILENO); |
64 | exit(EXIT_FAILURE); |
65 | } |
66 | #else |
67 | # define die_if_nologin() ((void)0) |
68 | #endif |
69 | |
70 | #if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM |
71 | static int check_securetty(void) |
72 | { |
73 | char *buf = (char*)"/etc/securetty"; /* any non-NULL is ok */ |
74 | parser_t *parser = config_open2("/etc/securetty", fopen_for_read); |
75 | while (config_read(parser, &buf, 1, 1, "# \t", PARSE_NORMAL)) { |
76 | if (strcmp(buf, short_tty) == 0) |
77 | break; |
78 | buf = NULL; |
79 | } |
80 | config_close(parser); |
81 | /* buf != NULL here if config file was not found, empty |
82 | * or line was found which equals short_tty */ |
83 | return buf != NULL; |
84 | } |
85 | #else |
86 | static ALWAYS_INLINE int check_securetty(void) { return 1; } |
87 | #endif |
88 | |
89 | #if ENABLE_SELINUX |
90 | static void initselinux(char *username, char *full_tty, |
91 | security_context_t *user_sid) |
92 | { |
93 | security_context_t old_tty_sid, new_tty_sid; |
94 | |
95 | if (!is_selinux_enabled()) |
96 | return; |
97 | |
98 | if (get_default_context(username, NULL, user_sid)) { |
99 | bb_error_msg_and_die("can't get SID for %s", username); |
100 | } |
101 | if (getfilecon(full_tty, &old_tty_sid) < 0) { |
102 | bb_perror_msg_and_die("getfilecon(%s) failed", full_tty); |
103 | } |
104 | if (security_compute_relabel(*user_sid, old_tty_sid, |
105 | SECCLASS_CHR_FILE, &new_tty_sid) != 0) { |
106 | bb_perror_msg_and_die("security_change_sid(%s) failed", full_tty); |
107 | } |
108 | if (setfilecon(full_tty, new_tty_sid) != 0) { |
109 | bb_perror_msg_and_die("chsid(%s, %s) failed", full_tty, new_tty_sid); |
110 | } |
111 | } |
112 | #endif |
113 | |
114 | #if ENABLE_LOGIN_SCRIPTS |
115 | static void run_login_script(struct passwd *pw, char *full_tty) |
116 | { |
117 | char *t_argv[2]; |
118 | |
119 | t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT"); |
120 | if (t_argv[0]) { |
121 | t_argv[1] = NULL; |
122 | xsetenv("LOGIN_TTY", full_tty); |
123 | xsetenv("LOGIN_USER", pw->pw_name); |
124 | xsetenv("LOGIN_UID", utoa(pw->pw_uid)); |
125 | xsetenv("LOGIN_GID", utoa(pw->pw_gid)); |
126 | xsetenv("LOGIN_SHELL", pw->pw_shell); |
127 | spawn_and_wait(t_argv); /* NOMMU-friendly */ |
128 | unsetenv("LOGIN_TTY"); |
129 | unsetenv("LOGIN_USER"); |
130 | unsetenv("LOGIN_UID"); |
131 | unsetenv("LOGIN_GID"); |
132 | unsetenv("LOGIN_SHELL"); |
133 | } |
134 | } |
135 | #else |
136 | void run_login_script(struct passwd *pw, char *full_tty); |
137 | #endif |
138 | |
139 | static void get_username_or_die(char *buf, int size_buf) |
140 | { |
141 | int c, cntdown; |
142 | |
143 | cntdown = EMPTY_USERNAME_COUNT; |
144 | prompt: |
145 | print_login_prompt(); |
146 | /* skip whitespace */ |
147 | do { |
148 | c = getchar(); |
149 | if (c == EOF) |
150 | exit(EXIT_FAILURE); |
151 | if (c == '\n') { |
152 | if (!--cntdown) |
153 | exit(EXIT_FAILURE); |
154 | goto prompt; |
155 | } |
156 | } while (isspace(c)); /* maybe isblank? */ |
157 | |
158 | *buf++ = c; |
159 | if (!fgets(buf, size_buf-2, stdin)) |
160 | exit(EXIT_FAILURE); |
161 | if (!strchr(buf, '\n')) |
162 | exit(EXIT_FAILURE); |
163 | while ((unsigned char)*buf > ' ') |
164 | buf++; |
165 | *buf = '\0'; |
166 | } |
167 | |
168 | static void motd(void) |
169 | { |
170 | int fd; |
171 | |
172 | fd = open(bb_path_motd_file, O_RDONLY); |
173 | if (fd >= 0) { |
174 | fflush_all(); |
175 | bb_copyfd_eof(fd, STDOUT_FILENO); |
176 | close(fd); |
177 | } |
178 | } |
179 | |
180 | static void alarm_handler(int sig UNUSED_PARAM) |
181 | { |
182 | /* This is the escape hatch! Poor serial line users and the like |
183 | * arrive here when their connection is broken. |
184 | * We don't want to block here */ |
185 | ndelay_on(1); |
186 | printf("\r\nLogin timed out after %d seconds\r\n", TIMEOUT); |
187 | fflush_all(); |
188 | /* unix API is brain damaged regarding O_NONBLOCK, |
189 | * we should undo it, or else we can affect other processes */ |
190 | ndelay_off(1); |
191 | _exit(EXIT_SUCCESS); |
192 | } |
193 | |
194 | int login_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
195 | int login_main(int argc UNUSED_PARAM, char **argv) |
196 | { |
197 | enum { |
198 | LOGIN_OPT_f = (1<<0), |
199 | LOGIN_OPT_h = (1<<1), |
200 | LOGIN_OPT_p = (1<<2), |
201 | }; |
202 | char *fromhost; |
203 | char username[USERNAME_SIZE]; |
204 | const char *shell; |
205 | int run_by_root; |
206 | unsigned opt; |
207 | int count = 0; |
208 | struct passwd *pw; |
209 | char *opt_host = NULL; |
210 | char *opt_user = opt_user; /* for compiler */ |
211 | char *full_tty; |
212 | IF_SELINUX(security_context_t user_sid = NULL;) |
213 | #if ENABLE_PAM |
214 | int pamret; |
215 | pam_handle_t *pamh; |
216 | const char *pamuser; |
217 | const char *failed_msg; |
218 | struct passwd pwdstruct; |
219 | char pwdbuf[256]; |
220 | #endif |
221 | |
222 | username[0] = '\0'; |
223 | signal(SIGALRM, alarm_handler); |
224 | alarm(TIMEOUT); |
225 | |
226 | /* More of suid paranoia if called by non-root: */ |
227 | /* Clear dangerous stuff, set PATH */ |
228 | run_by_root = !sanitize_env_if_suid(); |
229 | |
230 | /* Mandatory paranoia for suid applet: |
231 | * ensure that fd# 0,1,2 are opened (at least to /dev/null) |
232 | * and any extra open fd's are closed. |
233 | * (The name of the function is misleading. Not daemonizing here.) */ |
234 | bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL); |
235 | |
236 | opt = getopt32(argv, "f:h:p", &opt_user, &opt_host); |
237 | if (opt & LOGIN_OPT_f) { |
238 | if (!run_by_root) |
239 | bb_error_msg_and_die("-f is for root only"); |
240 | safe_strncpy(username, opt_user, sizeof(username)); |
241 | } |
242 | argv += optind; |
243 | if (argv[0]) /* user from command line (getty) */ |
244 | safe_strncpy(username, argv[0], sizeof(username)); |
245 | |
246 | /* Let's find out and memorize our tty */ |
247 | if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO) || !isatty(STDERR_FILENO)) |
248 | return EXIT_FAILURE; /* Must be a terminal */ |
249 | full_tty = xmalloc_ttyname(STDIN_FILENO); |
250 | if (!full_tty) |
251 | full_tty = xstrdup("UNKNOWN"); |
252 | short_tty = skip_dev_pfx(full_tty); |
253 | |
254 | if (opt_host) { |
255 | fromhost = xasprintf(" on '%s' from '%s'", short_tty, opt_host); |
256 | } else { |
257 | fromhost = xasprintf(" on '%s'", short_tty); |
258 | } |
259 | |
260 | /* Was breaking "login <username>" from shell command line: */ |
261 | /*bb_setpgrp();*/ |
262 | |
263 | openlog(applet_name, LOG_PID | LOG_CONS, LOG_AUTH); |
264 | |
265 | while (1) { |
266 | /* flush away any type-ahead (as getty does) */ |
267 | ioctl(0, TCFLSH, TCIFLUSH); |
268 | |
269 | if (!username[0]) |
270 | get_username_or_die(username, sizeof(username)); |
271 | |
272 | #if ENABLE_PAM |
273 | pamret = pam_start("login", username, &conv, &pamh); |
274 | if (pamret != PAM_SUCCESS) { |
275 | failed_msg = "start"; |
276 | goto pam_auth_failed; |
277 | } |
278 | /* set TTY (so things like securetty work) */ |
279 | pamret = pam_set_item(pamh, PAM_TTY, short_tty); |
280 | if (pamret != PAM_SUCCESS) { |
281 | failed_msg = "set_item(TTY)"; |
282 | goto pam_auth_failed; |
283 | } |
284 | pamret = pam_authenticate(pamh, 0); |
285 | if (pamret != PAM_SUCCESS) { |
286 | failed_msg = "authenticate"; |
287 | goto pam_auth_failed; |
288 | /* TODO: or just "goto auth_failed" |
289 | * since user seems to enter wrong password |
290 | * (in this case pamret == 7) |
291 | */ |
292 | } |
293 | /* check that the account is healthy */ |
294 | pamret = pam_acct_mgmt(pamh, 0); |
295 | if (pamret != PAM_SUCCESS) { |
296 | failed_msg = "acct_mgmt"; |
297 | goto pam_auth_failed; |
298 | } |
299 | /* read user back */ |
300 | pamuser = NULL; |
301 | /* gcc: "dereferencing type-punned pointer breaks aliasing rules..." |
302 | * thus we cast to (void*) */ |
303 | if (pam_get_item(pamh, PAM_USER, (void*)&pamuser) != PAM_SUCCESS) { |
304 | failed_msg = "get_item(USER)"; |
305 | goto pam_auth_failed; |
306 | } |
307 | if (!pamuser || !pamuser[0]) |
308 | goto auth_failed; |
309 | safe_strncpy(username, pamuser, sizeof(username)); |
310 | /* Don't use "pw = getpwnam(username);", |
311 | * PAM is said to be capable of destroying static storage |
312 | * used by getpwnam(). We are using safe(r) function */ |
313 | pw = NULL; |
314 | getpwnam_r(username, &pwdstruct, pwdbuf, sizeof(pwdbuf), &pw); |
315 | if (!pw) |
316 | goto auth_failed; |
317 | pamret = pam_open_session(pamh, 0); |
318 | if (pamret != PAM_SUCCESS) { |
319 | failed_msg = "open_session"; |
320 | goto pam_auth_failed; |
321 | } |
322 | pamret = pam_setcred(pamh, PAM_ESTABLISH_CRED); |
323 | if (pamret != PAM_SUCCESS) { |
324 | failed_msg = "setcred"; |
325 | goto pam_auth_failed; |
326 | } |
327 | break; /* success, continue login process */ |
328 | |
329 | pam_auth_failed: |
330 | /* syslog, because we don't want potential attacker |
331 | * to know _why_ login failed */ |
332 | syslog(LOG_WARNING, "pam_%s call failed: %s (%d)", failed_msg, |
333 | pam_strerror(pamh, pamret), pamret); |
334 | safe_strncpy(username, "UNKNOWN", sizeof(username)); |
335 | #else /* not PAM */ |
336 | pw = getpwnam(username); |
337 | if (!pw) { |
338 | strcpy(username, "UNKNOWN"); |
339 | goto fake_it; |
340 | } |
341 | |
342 | if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*') |
343 | goto auth_failed; |
344 | |
345 | if (opt & LOGIN_OPT_f) |
346 | break; /* -f USER: success without asking passwd */ |
347 | |
348 | if (pw->pw_uid == 0 && !check_securetty()) |
349 | goto auth_failed; |
350 | |
351 | /* Don't check the password if password entry is empty (!) */ |
352 | if (!pw->pw_passwd[0]) |
353 | break; |
354 | fake_it: |
355 | /* authorization takes place here */ |
356 | if (correct_password(pw)) |
357 | break; |
358 | #endif /* ENABLE_PAM */ |
359 | auth_failed: |
360 | opt &= ~LOGIN_OPT_f; |
361 | bb_do_delay(FAIL_DELAY); |
362 | /* TODO: doesn't sound like correct English phrase to me */ |
363 | puts("Login incorrect"); |
364 | if (++count == 3) { |
365 | syslog(LOG_WARNING, "invalid password for '%s'%s", |
366 | username, fromhost); |
367 | return EXIT_FAILURE; |
368 | } |
369 | username[0] = '\0'; |
370 | } /* while (1) */ |
371 | |
372 | alarm(0); |
373 | /* We can ignore /etc/nologin if we are logging in as root, |
374 | * it doesn't matter whether we are run by root or not */ |
375 | if (pw->pw_uid != 0) |
376 | die_if_nologin(); |
377 | |
378 | IF_SELINUX(initselinux(username, full_tty, &user_sid)); |
379 | |
380 | /* Try these, but don't complain if they fail. |
381 | * _f_chown is safe wrt race t=ttyname(0);...;chown(t); */ |
382 | fchown(0, pw->pw_uid, pw->pw_gid); |
383 | fchmod(0, 0600); |
384 | |
385 | update_utmp(getpid(), USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL); |
386 | |
387 | /* We trust environment only if we run by root */ |
388 | if (ENABLE_LOGIN_SCRIPTS && run_by_root) |
389 | run_login_script(pw, full_tty); |
390 | |
391 | change_identity(pw); |
392 | shell = pw->pw_shell; |
393 | if (!shell || !shell[0]) |
394 | shell = DEFAULT_SHELL; |
395 | setup_environment(shell, |
396 | (!(opt & LOGIN_OPT_p) * SETUP_ENV_CLEARENV) + SETUP_ENV_CHANGEENV, |
397 | pw); |
398 | |
399 | motd(); |
400 | |
401 | if (pw->pw_uid == 0) |
402 | syslog(LOG_INFO, "root login%s", fromhost); |
403 | |
404 | /* well, a simple setexeccon() here would do the job as well, |
405 | * but let's play the game for now */ |
406 | IF_SELINUX(set_current_security_context(user_sid);) |
407 | |
408 | // util-linux login also does: |
409 | // /* start new session */ |
410 | // setsid(); |
411 | // /* TIOCSCTTY: steal tty from other process group */ |
412 | // if (ioctl(0, TIOCSCTTY, 1)) error_msg... |
413 | // BBox login used to do this (see above): |
414 | // bb_setpgrp(); |
415 | // If this stuff is really needed, add it and explain why! |
416 | |
417 | /* Set signals to defaults */ |
418 | /* Non-ignored signals revert to SIG_DFL on exec anyway */ |
419 | /*signal(SIGALRM, SIG_DFL);*/ |
420 | |
421 | /* Is this correct? This way user can ctrl-c out of /etc/profile, |
422 | * potentially creating security breach (tested with bash 3.0). |
423 | * But without this, bash 3.0 will not enable ctrl-c either. |
424 | * Maybe bash is buggy? |
425 | * Need to find out what standards say about /bin/login - |
426 | * should we leave SIGINT etc enabled or disabled? */ |
427 | signal(SIGINT, SIG_DFL); |
428 | |
429 | /* Exec login shell with no additional parameters */ |
430 | run_shell(shell, 1, NULL, NULL); |
431 | |
432 | /* return EXIT_FAILURE; - not reached */ |
433 | } |