Contents of /trunk/mkinitrd-magellan/busybox/loginutils/login.c
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Sat Sep 1 22:45:15 2007 UTC (17 years ago) by niro
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Sat Sep 1 22:45:15 2007 UTC (17 years ago) by niro
File MIME type: text/plain
File size: 10019 byte(s)
-import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
4 | */ |
5 | |
6 | #include "busybox.h" |
7 | #include <utmp.h> |
8 | #include <sys/resource.h> |
9 | #include <syslog.h> |
10 | |
11 | #ifdef CONFIG_SELINUX |
12 | #include <selinux/selinux.h> /* for is_selinux_enabled() */ |
13 | #include <selinux/get_context_list.h> /* for get_default_context() */ |
14 | #include <selinux/flask.h> /* for security class definitions */ |
15 | #include <errno.h> |
16 | #endif |
17 | |
18 | enum { |
19 | TIMEOUT = 60, |
20 | EMPTY_USERNAME_COUNT = 10, |
21 | USERNAME_SIZE = 32, |
22 | TTYNAME_SIZE = 32, |
23 | }; |
24 | |
25 | static char full_tty[TTYNAME_SIZE]; |
26 | static char* short_tty = full_tty; |
27 | |
28 | #if ENABLE_FEATURE_UTMP |
29 | /* vv Taken from tinylogin utmp.c vv */ |
30 | /* |
31 | * read_or_build_utent - see if utmp file is correct for this process |
32 | * |
33 | * System V is very picky about the contents of the utmp file |
34 | * and requires that a slot for the current process exist. |
35 | * The utmp file is scanned for an entry with the same process |
36 | * ID. If no entry exists the process exits with a message. |
37 | * |
38 | * The "picky" flag is for network and other logins that may |
39 | * use special flags. It allows the pid checks to be overridden. |
40 | * This means that getty should never invoke login with any |
41 | * command line flags. |
42 | */ |
43 | |
44 | static struct utmp utent; |
45 | |
46 | static void read_or_build_utent(int picky) |
47 | { |
48 | struct utmp *ut; |
49 | pid_t pid = getpid(); |
50 | |
51 | setutent(); |
52 | |
53 | /* First, try to find a valid utmp entry for this process. */ |
54 | while ((ut = getutent())) |
55 | if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] && |
56 | (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS)) |
57 | break; |
58 | |
59 | /* If there is one, just use it, otherwise create a new one. */ |
60 | if (ut) { |
61 | utent = *ut; |
62 | } else { |
63 | if (picky) |
64 | bb_error_msg_and_die("no utmp entry found"); |
65 | |
66 | memset(&utent, 0, sizeof(utent)); |
67 | utent.ut_type = LOGIN_PROCESS; |
68 | utent.ut_pid = pid; |
69 | strncpy(utent.ut_line, short_tty, sizeof(utent.ut_line)); |
70 | /* This one is only 4 chars wide. Try to fit something |
71 | * remotely meaningful by skipping "tty"... */ |
72 | strncpy(utent.ut_id, short_tty + 3, sizeof(utent.ut_id)); |
73 | strncpy(utent.ut_user, "LOGIN", sizeof(utent.ut_user)); |
74 | utent.ut_time = time(NULL); |
75 | } |
76 | if (!picky) /* root login */ |
77 | memset(utent.ut_host, 0, sizeof(utent.ut_host)); |
78 | } |
79 | |
80 | /* |
81 | * write_utent - put a USER_PROCESS entry in the utmp file |
82 | * |
83 | * write_utent changes the type of the current utmp entry to |
84 | * USER_PROCESS. the wtmp file will be updated as well. |
85 | */ |
86 | static void write_utent(const char *username) |
87 | { |
88 | utent.ut_type = USER_PROCESS; |
89 | strncpy(utent.ut_user, username, sizeof(utent.ut_user)); |
90 | utent.ut_time = time(NULL); |
91 | /* other fields already filled in by read_or_build_utent above */ |
92 | setutent(); |
93 | pututline(&utent); |
94 | endutent(); |
95 | #if ENABLE_FEATURE_WTMP |
96 | if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) { |
97 | close(creat(bb_path_wtmp_file, 0664)); |
98 | } |
99 | updwtmp(bb_path_wtmp_file, &utent); |
100 | #endif |
101 | } |
102 | #else /* !ENABLE_FEATURE_UTMP */ |
103 | static inline void read_or_build_utent(int ATTRIBUTE_UNUSED picky) {} |
104 | static inline void write_utent(const char ATTRIBUTE_UNUSED *username) {} |
105 | #endif /* !ENABLE_FEATURE_UTMP */ |
106 | |
107 | static void die_if_nologin_and_non_root(int amroot) |
108 | { |
109 | FILE *fp; |
110 | int c; |
111 | |
112 | if (access(bb_path_nologin_file, F_OK)) |
113 | return; |
114 | |
115 | fp = fopen(bb_path_nologin_file, "r"); |
116 | if (fp) { |
117 | while ((c = getc(fp)) != EOF) |
118 | putchar((c=='\n') ? '\r' : c); |
119 | fflush(stdout); |
120 | fclose(fp); |
121 | } else |
122 | puts("\r\nSystem closed for routine maintenance\r"); |
123 | if (!amroot) |
124 | exit(1); |
125 | puts("\r\n[Disconnect bypassed -- root login allowed.]\r"); |
126 | } |
127 | |
128 | #if ENABLE_FEATURE_SECURETTY |
129 | static int check_securetty(void) |
130 | { |
131 | FILE *fp; |
132 | int i; |
133 | char buf[BUFSIZ]; |
134 | |
135 | fp = fopen(bb_path_securetty_file, "r"); |
136 | if (!fp) { |
137 | /* A missing securetty file is not an error. */ |
138 | return 1; |
139 | } |
140 | while (fgets(buf, sizeof(buf)-1, fp)) { |
141 | for (i = strlen(buf)-1; i>=0; --i) { |
142 | if (!isspace(buf[i])) |
143 | break; |
144 | } |
145 | buf[++i] = '\0'; |
146 | if ((buf[0]=='\0') || (buf[0]=='#')) |
147 | continue; |
148 | if (strcmp(buf, short_tty) == 0) { |
149 | fclose(fp); |
150 | return 1; |
151 | } |
152 | } |
153 | fclose(fp); |
154 | return 0; |
155 | } |
156 | #else |
157 | static inline int check_securetty(void) { return 1; } |
158 | #endif |
159 | |
160 | static void get_username_or_die(char *buf, int size_buf) |
161 | { |
162 | int c, cntdown; |
163 | cntdown = EMPTY_USERNAME_COUNT; |
164 | prompt: |
165 | /* skip whitespace */ |
166 | print_login_prompt(); |
167 | do { |
168 | c = getchar(); |
169 | if (c == EOF) exit(1); |
170 | if (c == '\n') { |
171 | if (!--cntdown) exit(1); |
172 | goto prompt; |
173 | } |
174 | } while (isspace(c)); |
175 | |
176 | *buf++ = c; |
177 | if (!fgets(buf, size_buf-2, stdin)) |
178 | exit(1); |
179 | if (!strchr(buf, '\n')) |
180 | exit(1); |
181 | while (isgraph(*buf)) buf++; |
182 | *buf = '\0'; |
183 | } |
184 | |
185 | static void motd(void) |
186 | { |
187 | FILE *fp; |
188 | int c; |
189 | |
190 | fp = fopen(bb_path_motd_file, "r"); |
191 | if (fp) { |
192 | while ((c = getc(fp)) != EOF) |
193 | putchar(c); |
194 | fclose(fp); |
195 | } |
196 | } |
197 | |
198 | static void nonblock(int fd) |
199 | { |
200 | fcntl(fd, F_SETFL, O_NONBLOCK | fcntl(fd, F_GETFL)); |
201 | } |
202 | |
203 | static void alarm_handler(int sig ATTRIBUTE_UNUSED) |
204 | { |
205 | /* This is the escape hatch! Poor serial line users and the like |
206 | * arrive here when their connection is broken. |
207 | * We don't want to block here */ |
208 | nonblock(1); |
209 | nonblock(2); |
210 | bb_info_msg("\r\nLogin timed out after %d seconds\r", TIMEOUT); |
211 | exit(EXIT_SUCCESS); |
212 | } |
213 | |
214 | int login_main(int argc, char **argv) |
215 | { |
216 | enum { |
217 | LOGIN_OPT_f = (1<<0), |
218 | LOGIN_OPT_h = (1<<1), |
219 | LOGIN_OPT_p = (1<<2), |
220 | }; |
221 | char fromhost[512]; |
222 | char username[USERNAME_SIZE]; |
223 | const char *tmp; |
224 | int amroot; |
225 | unsigned opt; |
226 | int count = 0; |
227 | struct passwd *pw; |
228 | char *opt_host = NULL; |
229 | char *opt_user = NULL; |
230 | USE_SELINUX(security_context_t user_sid = NULL;) |
231 | |
232 | username[0] = '\0'; |
233 | amroot = (getuid() == 0); |
234 | signal(SIGALRM, alarm_handler); |
235 | alarm(TIMEOUT); |
236 | |
237 | opt = getopt32(argc, argv, "f:h:p", &opt_user, &opt_host); |
238 | if (opt & LOGIN_OPT_f) { |
239 | if (!amroot) |
240 | bb_error_msg_and_die("-f is for root only"); |
241 | safe_strncpy(username, opt_user, sizeof(username)); |
242 | } |
243 | if (optind < argc) /* user from command line (getty) */ |
244 | safe_strncpy(username, argv[optind], sizeof(username)); |
245 | |
246 | /* Let's find out and memorize our tty */ |
247 | if (!isatty(0) || !isatty(1) || !isatty(2)) |
248 | return EXIT_FAILURE; /* Must be a terminal */ |
249 | safe_strncpy(full_tty, "UNKNOWN", sizeof(full_tty)); |
250 | tmp = ttyname(0); |
251 | if (tmp) { |
252 | safe_strncpy(full_tty, tmp, sizeof(full_tty)); |
253 | if (strncmp(full_tty, "/dev/", 5) == 0) |
254 | short_tty = full_tty + 5; |
255 | } |
256 | |
257 | read_or_build_utent(!amroot); |
258 | |
259 | if (opt_host) { |
260 | USE_FEATURE_UTMP( |
261 | safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host)); |
262 | ) |
263 | snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s' from " |
264 | "'%.200s'", short_tty, opt_host); |
265 | } |
266 | else |
267 | snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s'", short_tty); |
268 | |
269 | bb_setpgrp; |
270 | |
271 | openlog(applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH); |
272 | |
273 | while (1) { |
274 | if (!username[0]) |
275 | get_username_or_die(username, sizeof(username)); |
276 | |
277 | pw = getpwnam(username); |
278 | if (!pw) { |
279 | safe_strncpy(username, "UNKNOWN", sizeof(username)); |
280 | goto auth_failed; |
281 | } |
282 | |
283 | if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*') |
284 | goto auth_failed; |
285 | |
286 | if (opt & LOGIN_OPT_f) |
287 | break; /* -f USER: success without asking passwd */ |
288 | |
289 | if (pw->pw_uid == 0 && !check_securetty()) |
290 | goto auth_failed; |
291 | |
292 | /* Don't check the password if password entry is empty (!) */ |
293 | if (!pw->pw_passwd[0]) |
294 | break; |
295 | |
296 | /* authorization takes place here */ |
297 | if (correct_password(pw)) |
298 | break; |
299 | |
300 | auth_failed: |
301 | opt &= ~LOGIN_OPT_f; |
302 | bb_do_delay(FAIL_DELAY); |
303 | puts("Login incorrect"); |
304 | if (++count == 3) { |
305 | syslog(LOG_WARNING, "invalid password for '%s'%s", |
306 | username, fromhost); |
307 | return EXIT_FAILURE; |
308 | } |
309 | username[0] = '\0'; |
310 | } |
311 | |
312 | alarm(0); |
313 | die_if_nologin_and_non_root(pw->pw_uid == 0); |
314 | |
315 | write_utent(username); |
316 | |
317 | #ifdef CONFIG_SELINUX |
318 | if (is_selinux_enabled()) { |
319 | security_context_t old_tty_sid, new_tty_sid; |
320 | |
321 | if (get_default_context(username, NULL, &user_sid)) { |
322 | bb_error_msg_and_die("cannot get SID for %s", |
323 | username); |
324 | } |
325 | if (getfilecon(full_tty, &old_tty_sid) < 0) { |
326 | bb_perror_msg_and_die("getfilecon(%s) failed", |
327 | full_tty); |
328 | } |
329 | if (security_compute_relabel(user_sid, old_tty_sid, |
330 | SECCLASS_CHR_FILE, &new_tty_sid) != 0) { |
331 | bb_perror_msg_and_die("security_change_sid(%s) failed", |
332 | full_tty); |
333 | } |
334 | if (setfilecon(full_tty, new_tty_sid) != 0) { |
335 | bb_perror_msg_and_die("chsid(%s, %s) failed", |
336 | full_tty, new_tty_sid); |
337 | } |
338 | } |
339 | #endif |
340 | /* Try these, but don't complain if they fail. |
341 | * _f_chown is safe wrt race t=ttyname(0);...;chown(t); */ |
342 | fchown(0, pw->pw_uid, pw->pw_gid); |
343 | fchmod(0, 0600); |
344 | |
345 | /* TODO: be nommu-friendly, use spawn? */ |
346 | if (ENABLE_LOGIN_SCRIPTS) { |
347 | char *script = getenv("LOGIN_PRE_SUID_SCRIPT"); |
348 | if (script) { |
349 | char *t_argv[2] = { script, NULL }; |
350 | switch (fork()) { |
351 | case -1: break; |
352 | case 0: /* child */ |
353 | xchdir("/"); |
354 | setenv("LOGIN_TTY", full_tty, 1); |
355 | setenv("LOGIN_USER", pw->pw_name, 1); |
356 | setenv("LOGIN_UID", utoa(pw->pw_uid), 1); |
357 | setenv("LOGIN_GID", utoa(pw->pw_gid), 1); |
358 | setenv("LOGIN_SHELL", pw->pw_shell, 1); |
359 | execvp(script, t_argv); |
360 | exit(1); |
361 | default: /* parent */ |
362 | wait(NULL); |
363 | } |
364 | } |
365 | } |
366 | |
367 | change_identity(pw); |
368 | tmp = pw->pw_shell; |
369 | if (!tmp || !*tmp) |
370 | tmp = DEFAULT_SHELL; |
371 | setup_environment(tmp, 1, !(opt & LOGIN_OPT_p), pw); |
372 | |
373 | motd(); |
374 | |
375 | if (pw->pw_uid == 0) |
376 | syslog(LOG_INFO, "root login%s", fromhost); |
377 | #ifdef CONFIG_SELINUX |
378 | /* well, a simple setexeccon() here would do the job as well, |
379 | * but let's play the game for now */ |
380 | set_current_security_context(user_sid); |
381 | #endif |
382 | |
383 | // util-linux login also does: |
384 | // /* start new session */ |
385 | // setsid(); |
386 | // /* TIOCSCTTY: steal tty from other process group */ |
387 | // if (ioctl(0, TIOCSCTTY, 1)) error_msg... |
388 | |
389 | /* set signals to defaults */ |
390 | signal(SIGALRM, SIG_DFL); |
391 | /* Is this correct? This way user can ctrl-c out of /etc/profile, |
392 | * potentially creating security breach (tested with bash 3.0). |
393 | * But without this, bash 3.0 will not enable ctrl-c either. |
394 | * Maybe bash is buggy? |
395 | * Need to find out what standards say about /bin/login - |
396 | * should it leave SIGINT etc enabled or disabled? */ |
397 | signal(SIGINT, SIG_DFL); |
398 | |
399 | run_shell(tmp, 1, 0, 0); /* exec the shell finally */ |
400 | |
401 | return EXIT_FAILURE; |
402 | } |