Remove unused variable serial from tcfinal().
[sysvinit.git] / src / sulogin.c
1 /*
2 * sulogin This program gives Linux machines a reasonable
3 * secure way to boot single user. It forces the
4 * user to supply the root password before a
5 * shell is started.
6 *
7 * If there is a shadow password file and the
8 * encrypted root password is "x" the shadow
9 * password will be used.
10 *
11 * Version: @(#)sulogin 2.85-3 23-Apr-2003 miquels@cistron.nl
12 *
13 * Copyright (C) 1998-2003 Miquel van Smoorenburg.
14 *
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
19 *
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
24 *
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software
27 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28 *
29 */
30
31 #include <sys/mman.h>
32 #include <sys/types.h>
33 #include <sys/stat.h>
34 #include <sys/wait.h>
35 #include <stdio.h>
36 #include <string.h>
37 #include <stdlib.h>
38 #include <unistd.h>
39 #include <fcntl.h>
40 #include <signal.h>
41 #include <pwd.h>
42 #include <shadow.h>
43 #include <termios.h>
44 #include <sys/ttydefaults.h>
45 #include <errno.h>
46 #include <sys/ioctl.h>
47 #ifdef __linux__
48 # include <sys/statfs.h>
49 # include <sys/mount.h>
50 # include <linux/fs.h>
51 # include <linux/magic.h>
52 # include <linux/major.h>
53 # ifndef TMPFS_MAGIC
54 # define TMPFS_MAGIC 0x01021994
55 # endif
56 # ifndef MNT_DETACH
57 # define MNT_DETACH 2
58 # endif
59 # define dovoid(f) if ((f)){}
60 #endif
61
62 #define BS CTRL('h')
63 #define NL CTRL('j')
64 #define CR CTRL('m')
65
66 #ifdef WITH_SELINUX
67 # include <selinux/selinux.h>
68 # include <selinux/get_context_list.h>
69 #endif
70
71 #include "consoles.h"
72 #define CONMAX 16
73
74 #define CHECK_DES 1
75 #define CHECK_MD5 1
76
77 #define F_PASSWD "/etc/passwd"
78 #define F_SHADOW "/etc/shadow"
79 #define BINSH "/bin/sh"
80 #define STATICSH "/bin/sash"
81
82 char *Version = "@(#)sulogin 2.85-3 23-Apr-2003 miquels@cistron.nl";
83
84 static int timeout;
85 static int profile;
86 static volatile uint32_t openfd; /* Remember higher file descriptors */
87 static volatile uint32_t *usemask;
88
89 static sighandler_t saved_sigint = SIG_DFL;
90 static sighandler_t saved_sigtstp = SIG_DFL;
91 static sighandler_t saved_sigquit = SIG_DFL;
92 static sighandler_t saved_sighup = SIG_DFL;
93
94 static volatile sig_atomic_t alarm_rised;
95 static volatile sig_atomic_t sigchild;
96
97 #ifndef IUCLC
98 # define IUCLC 0
99 #endif
100
101 /*
102 * Fix the tty modes and set reasonable defaults.
103 */
104 static
105 void tcinit(struct console *con)
106 {
107 int serial, flags;
108 struct termios *tio = &con->tio;
109 int fd = con->fd;
110
111 /* Expected error */
112 serial = errno = 0;
113
114 /* Get line attributes */
115 if (tcgetattr(fd, tio) < 0) {
116 con->flags |= CON_NOTTY;
117 return;
118 }
119
120 /* Handle serial lines here */
121 if (ioctl (fd, TIOCMGET, (char*)&serial) == 0) {
122 speed_t ispeed, ospeed;
123 struct winsize ws;
124
125 /* this is a modem line */
126 con->flags |= CON_SERIAL;
127
128 /* Flush input and output queues on modem lines */
129 (void) tcflush(fd, TCIOFLUSH);
130
131 ispeed = cfgetispeed(tio);
132 ospeed = cfgetospeed(tio);
133
134 if (!ispeed) ispeed = TTYDEF_SPEED;
135 if (!ospeed) ospeed = TTYDEF_SPEED;
136
137 tio->c_iflag = tio->c_lflag = tio->c_oflag = 0;
138 tio->c_cflag = CREAD | CS8 | HUPCL | (tio->c_cflag & CLOCAL);
139
140 cfsetispeed(tio, ispeed);
141 cfsetospeed(tio, ospeed);
142
143 tio->c_line = 0;
144 tio->c_cc[VTIME] = 0;
145 tio->c_cc[VMIN] = 1;
146
147 if (ioctl(fd, TIOCGWINSZ, &ws) == 0) {
148 int set = 0;
149 if (ws.ws_row == 0) {
150 ws.ws_row = 24;
151 set++;
152 }
153 if (ws.ws_col == 0) {
154 ws.ws_col = 80;
155 set++;
156 }
157 (void)ioctl(fd, TIOCSWINSZ, &ws);
158 }
159
160 goto setattr;
161 }
162 #if defined(SANE_TIO) && (SANE_TIO == 1)
163 /*
164 * Use defaults of <sys/ttydefaults.h> for base settings
165 * of a local terminal line like a virtual console.
166 */
167 tio->c_iflag |= TTYDEF_IFLAG;
168 tio->c_oflag |= TTYDEF_OFLAG;
169 tio->c_lflag |= TTYDEF_LFLAG;
170 # ifdef CBAUD
171 tio->c_lflag &= ~CBAUD;
172 # endif
173 tio->c_cflag |= (B38400 | TTYDEF_CFLAG);
174
175 /* Sane setting, allow eight bit characters, no carriage return delay
176 * the same result as `stty sane cr0 pass8'
177 */
178 tio->c_iflag |= (BRKINT | ICRNL | IMAXBEL);
179 tio->c_iflag &= ~(IGNBRK | INLCR | IGNCR | IXOFF | IUCLC | IXANY | INPCK | ISTRIP);
180 tio->c_oflag |= (OPOST | ONLCR | NL0 | CR0 | TAB0 | BS0 | VT0 | FF0);
181 tio->c_oflag &= ~(OLCUC | OCRNL | ONOCR | ONLRET | OFILL | OFDEL |\
182 NLDLY|CRDLY|TABDLY|BSDLY|VTDLY|FFDLY);
183 tio->c_lflag |= (ISIG | ICANON | IEXTEN | ECHO|ECHOE|ECHOK|ECHOKE);
184 tio->c_lflag &= ~(ECHONL|ECHOCTL|ECHOPRT | NOFLSH | XCASE | TOSTOP);
185 tio->c_cflag |= (CREAD | CS8 | HUPCL);
186 tio->c_cflag &= ~(PARODD | PARENB);
187
188 /*
189 * VTIME and VMIN can overlap with VEOF and VEOL since they are
190 * only used for non-canonical mode. We just set the at the
191 * beginning, so nothing bad should happen.
192 */
193 tio->c_cc[VTIME] = 0;
194 tio->c_cc[VMIN] = CMIN;
195 tio->c_cc[VINTR] = CINTR;
196 tio->c_cc[VQUIT] = CQUIT;
197 tio->c_cc[VERASE] = CERASE; /* ASCII DEL (0177) */
198 tio->c_cc[VKILL] = CKILL;
199 tio->c_cc[VEOF] = CEOF;
200 # ifdef VSWTC
201 tio->c_cc[VSWTC] = _POSIX_VDISABLE;
202 # else
203 tio->c_cc[VSWTCH] = _POSIX_VDISABLE;
204 # endif
205 tio->c_cc[VSTART] = CSTART;
206 tio->c_cc[VSTOP] = CSTOP;
207 tio->c_cc[VSUSP] = CSUSP;
208 tio->c_cc[VEOL] = _POSIX_VDISABLE;
209 tio->c_cc[VREPRINT] = CREPRINT;
210 tio->c_cc[VDISCARD] = CDISCARD;
211 tio->c_cc[VWERASE] = CWERASE;
212 tio->c_cc[VLNEXT] = CLNEXT;
213 tio->c_cc[VEOL2] = _POSIX_VDISABLE;
214 #endif
215 setattr:
216 /* Set line attributes */
217 tcsetattr(fd, TCSANOW, tio);
218
219 /* Enable blocking mode for read and write */
220 if ((flags = fcntl(fd, F_GETFL, 0)) != -1)
221 (void)fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
222 }
223
224
225 /*
226 * Finalize the tty modes on modem lines.
227 */
228 static
229 void tcfinal(struct console *con)
230 {
231 struct termios *tio = &con->tio;
232 int fd = con->fd;
233
234 /* Expected error */
235 errno = 0;
236
237 if ((con->flags & CON_SERIAL) == 0) {
238 #ifdef __linux__
239 setenv("TERM", "linux", 1);
240 #else
241 setenv("TERM", "vt100", 1);
242 #endif
243 return;
244 }
245 if (con->flags & CON_NOTTY)
246 return;
247 setenv("TERM", "vt100", 1);
248
249 tio->c_iflag |= (IXON | IXOFF);
250 tio->c_lflag |= (ICANON | ISIG | ECHO|ECHOE|ECHOK|ECHOKE);
251 tio->c_oflag |= OPOST;
252
253 tio->c_cc[VINTR] = CINTR;
254 tio->c_cc[VQUIT] = CQUIT;
255 tio->c_cc[VERASE] = con->cp.erase;
256 tio->c_cc[VKILL] = con->cp.kill;
257 tio->c_cc[VEOF] = CEOF;
258 #ifdef VSWTC
259 tio->c_cc[VSWTC] = _POSIX_VDISABLE;
260 #else
261 tio->c_cc[VSWTCH] = _POSIX_VDISABLE;
262 #endif
263 tio->c_cc[VSTART] = CSTART;
264 tio->c_cc[VSTOP] = CSTOP;
265 tio->c_cc[VSUSP] = CSUSP;
266 tio->c_cc[VEOL] = _POSIX_VDISABLE;
267
268 if (con->cp.eol == CR) {
269 tio->c_iflag |= ICRNL;
270 tio->c_iflag &= ~(INLCR|IGNCR);
271 tio->c_oflag |= ONLCR;
272 tio->c_oflag &= ~(OCRNL|ONLRET);
273 }
274
275 switch (con->cp.parity) {
276 default:
277 case 0:
278 tio->c_cflag &= ~(PARODD | PARENB);
279 tio->c_iflag &= ~(INPCK | ISTRIP);
280 break;
281 case 1: /* odd parity */
282 tio->c_cflag |= PARODD;
283 /* fall through */
284 case 2: /* even parity */
285 tio->c_cflag |= PARENB;
286 tio->c_iflag |= (INPCK | ISTRIP);
287 /* fall through */
288 case (1 | 2): /* no parity bit */
289 tio->c_cflag &= ~CSIZE;
290 tio->c_cflag |= CS7;
291 break;
292 }
293
294 /* Set line attributes */
295 (void)tcsetattr(fd, TCSANOW, tio);
296 }
297
298 /*
299 * Called at timeout.
300 */
301 static
302 # ifdef __GNUC__
303 __attribute__((__noinline__))
304 void alrm_handler(int sig __attribute__((unused)))
305 # else
306 void alrm_handler(int sig)
307 # endif
308 {
309 alarm_rised++;
310 }
311
312 /*
313 * Called at timeout.
314 */
315 static
316 # ifdef __GNUC__
317 __attribute__((__noinline__))
318 void chld_handler(int sig __attribute__((unused)))
319 # else
320 void chld_handler(int sig)
321 # endif
322 {
323 sigchild++;
324 }
325
326 /*
327 * See if an encrypted password is valid. The encrypted
328 * password is checked for traditional-style DES and
329 * FreeBSD-style MD5 encryption.
330 */
331 static
332 int valid(const char *pass)
333 {
334 const char *s;
335 char id[5];
336 size_t len;
337 off_t off;
338
339 if (pass[0] == 0) return 1;
340 #if CHECK_MD5
341 if (pass[0] != '$') goto check_des;
342
343 /*
344 * up to 4 bytes for the signature e.g. $1$
345 */
346 for(s = pass+1; *s && *s != '$'; s++)
347 ;
348 if (*s++ != '$') return 0;
349 if ((off = (off_t)(s-pass)) > 4 || off < 3) return 0;
350
351 memset(id, '\0', sizeof(id));
352 strncpy(id, pass, off);
353
354 /*
355 * up to 16 bytes for the salt
356 */
357 for(; *s && *s != '$'; s++)
358 ;
359 if (*s++ != '$') return 0;
360 if ((off_t)(s-pass) > 16) return 0;
361 len = strlen(s);
362
363 /*
364 * the MD5 hash (128 bits or 16 bytes) encoded in base64 = 22 bytes
365 */
366 if ((strcmp(id, "$1$") == 0) && (len < 22 || len > 24)) return 0;
367
368 /*
369 * the SHA-256 hash 43 bytes
370 */
371 if ((strcmp(id, "$5$") == 0) && (len < 42 || len > 44)) return 0;
372
373 /*
374 * the SHA-512 hash 86 bytes
375 */
376 if ((strcmp(id, "$6$") == 0) && (len < 85 || len > 87)) return 0;
377
378 /*
379 * e.g. Blowfish hash
380 */
381 return 1;
382 check_des:
383 #endif
384 #if CHECK_DES
385 if (strlen(pass) != 13) return 0;
386 for (s = pass; *s; s++) {
387 if ((*s < '0' || *s > '9') &&
388 (*s < 'a' || *s > 'z') &&
389 (*s < 'A' || *s > 'Z') &&
390 *s != '.' && *s != '/') return 0;
391 }
392 #endif
393 return 1;
394 }
395
396 /*
397 * Set a variable if the value is not NULL.
398 */
399 static
400 void set(char **var, char *val)
401 {
402 if (val) *var = val;
403 }
404
405 /*
406 * Get the root password entry.
407 */
408 static
409 struct passwd *getrootpwent(int try_manually)
410 {
411 static struct passwd pwd;
412 struct passwd *pw;
413 struct spwd *spw;
414 FILE *fp;
415 static char line[256];
416 static char sline[256];
417 char *p;
418
419 /*
420 * First, we try to get the password the standard
421 * way using normal library calls.
422 */
423 if ((pw = getpwnam("root")) &&
424 !strcmp(pw->pw_passwd, "x") &&
425 (spw = getspnam("root")))
426 pw->pw_passwd = spw->sp_pwdp;
427 if (pw || !try_manually) return pw;
428
429 /*
430 * If we come here, we could not retrieve the root
431 * password through library calls and we try to
432 * read the password and shadow files manually.
433 */
434 pwd.pw_name = "root";
435 pwd.pw_passwd = "";
436 pwd.pw_gecos = "Super User";
437 pwd.pw_dir = "/";
438 pwd.pw_shell = "";
439 pwd.pw_uid = 0;
440 pwd.pw_gid = 0;
441
442 if ((fp = fopen(F_PASSWD, "r")) == NULL) {
443 perror(F_PASSWD);
444 return &pwd;
445 }
446
447 /*
448 * Find root in the password file.
449 */
450 while((p = fgets(line, 256, fp)) != NULL) {
451 if (strncmp(line, "root:", 5) != 0)
452 continue;
453 p += 5;
454 set(&pwd.pw_passwd, strsep(&p, ":"));
455 (void)strsep(&p, ":");
456 (void)strsep(&p, ":");
457 set(&pwd.pw_gecos, strsep(&p, ":"));
458 set(&pwd.pw_dir, strsep(&p, ":"));
459 set(&pwd.pw_shell, strsep(&p, "\n"));
460 p = line;
461 break;
462 }
463 fclose(fp);
464
465 /*
466 * If the encrypted password is valid
467 * or not found, return.
468 */
469 if (p == NULL) {
470 fprintf(stderr, "sulogin: %s: no entry for root\n\r", F_PASSWD);
471 return &pwd;
472 }
473 if (valid(pwd.pw_passwd)) return &pwd;
474
475 /*
476 * The password is invalid. If there is a
477 * shadow password, try it.
478 */
479 strcpy(pwd.pw_passwd, "");
480 if ((fp = fopen(F_SHADOW, "r")) == NULL) {
481 fprintf(stderr, "sulogin: %s: root password garbled\n\r", F_PASSWD);
482 return &pwd;
483 }
484 while((p = fgets(sline, 256, fp)) != NULL) {
485 if (strncmp(sline, "root:", 5) != 0)
486 continue;
487 p += 5;
488 set(&pwd.pw_passwd, strsep(&p, ":"));
489 break;
490 }
491 fclose(fp);
492
493 /*
494 * If the password is still invalid,
495 * NULL it, and return.
496 */
497 if (p == NULL) {
498 fprintf(stderr, "sulogin: %s: no entry for root\n\r", F_SHADOW);
499 strcpy(pwd.pw_passwd, "");
500 }
501 if (!valid(pwd.pw_passwd)) {
502 fprintf(stderr, "sulogin: %s: root password garbled\n\r", F_SHADOW);
503 strcpy(pwd.pw_passwd, ""); }
504 return &pwd;
505 }
506
507 /*
508 * Ask by prompt for the password.
509 */
510 static
511 void doprompt(const char *crypted, struct console *con)
512 {
513 struct termios tty;
514
515 if (con->flags & CON_SERIAL) {
516 tty = con->tio;
517 /*
518 * For prompting: map NL in output to CR-NL
519 * otherwise we may see stairs in the output.
520 */
521 tty.c_oflag |= (ONLCR | OPOST);
522 (void) tcsetattr(con->fd, TCSADRAIN, &tty);
523 }
524 if (con->file == (FILE*)0) {
525 if ((con->file = fdopen(con->fd, "r+")) == (FILE*)0)
526 goto err;
527 }
528 #if defined(USE_ONELINE)
529 if (crypted[0])
530 fprintf(con->file, "Give root password for login: ");
531 else
532 fprintf(con->file, "Press enter for login: ");
533 #else
534 if (crypted[0])
535 fprintf(con->file, "Give root password for maintenance\n\r");
536 else
537 fprintf(con->file, "Press enter for maintenance");
538 fprintf(con->file, "(or type Control-D to continue): ");
539 #endif
540 fflush(con->file);
541 err:
542 if (con->flags & CON_SERIAL)
543 (void) tcsetattr(con->fd, TCSADRAIN, &con->tio);
544 }
545
546 /*
547 * Make sure to have an own session and controlling terminal
548 */
549 static
550 void setup(struct console *con)
551 {
552 pid_t pid, pgrp, ppgrp, ttypgrp;
553 int fd;
554
555 if (con->flags & CON_NOTTY)
556 return;
557 fd = con->fd;
558
559 /*
560 * Only go through this trouble if the new
561 * tty doesn't fall in this process group.
562 */
563 pid = getpid();
564 pgrp = getpgid(0);
565 ppgrp = getpgid(getppid());
566 ttypgrp = tcgetpgrp(fd);
567
568 if (pgrp != ttypgrp && ppgrp != ttypgrp) {
569 if (pid != getsid(0)) {
570 if (pid == getpgid(0))
571 setpgid(0, getpgid(getppid()));
572 setsid();
573 }
574
575 signal(SIGHUP, SIG_IGN);
576 if (ttypgrp > 0)
577 ioctl(0, TIOCNOTTY, (char *)1);
578 signal(SIGHUP, saved_sighup);
579 if (fd > 0) close(0);
580 if (fd > 1) close(1);
581 if (fd > 2) close(2);
582
583 ioctl(fd, TIOCSCTTY, (char *)1);
584 tcsetpgrp(fd, ppgrp);
585 }
586 dup2(fd, 0);
587 dup2(fd, 1);
588 dup2(fd, 2);
589 con->fd = 0;
590
591 for (fd = 3; fd < 32; fd++) {
592 if (openfd & (1<<fd)) {
593 close(fd);
594 openfd &= ~(1<<fd);
595 }
596 }
597 }
598
599 /*
600 * Fetch the password. Note that there is no
601 * default timeout as we normally skip this during boot.
602 */
603 static
604 char *getpasswd(struct console *con)
605 {
606 static char pass[128], *ptr;
607 struct sigaction sa;
608 struct chardata *cp;
609 struct termios tty;
610 char *ret = pass;
611 unsigned char tc;
612 char c, ascval;
613 int eightbit;
614 int fd;
615
616 if (con->flags & CON_NOTTY)
617 goto out;
618 fd = con->fd;
619 cp = &con->cp;
620
621 tty = con->tio;
622 tty.c_iflag &= ~(IUCLC|IXON|IXOFF|IXANY);
623 tty.c_lflag &= ~(ECHO|ECHOE|ECHOK|ECHONL|TOSTOP|ISIG);
624 tc = (tcsetattr(fd, TCSAFLUSH, &tty) == 0);
625
626 sa.sa_handler = alrm_handler;
627 sa.sa_flags = 0;
628 sigaction(SIGALRM, &sa, NULL);
629 if (timeout) alarm(timeout);
630
631 ptr = &pass[0];
632 cp->eol = *ptr = '\0';
633
634 eightbit = ((con->flags & CON_SERIAL) == 0 || (tty.c_cflag & (PARODD|PARENB)) == 0);
635 while (cp->eol == '\0') {
636 if (read(fd, &c, 1) < 1) {
637 if (errno == EINTR || errno == EAGAIN) {
638 usleep(1000);
639 continue;
640 }
641 ret = (char*)0;
642 switch (errno) {
643 case 0:
644 case EIO:
645 case ESRCH:
646 case EINVAL:
647 case ENOENT:
648 break;
649 default:
650 fprintf(stderr, "sulogin: read(%s): %m\n\r", con->tty);
651 break;
652 }
653 goto quit;
654 }
655
656 if (eightbit)
657 ascval = c;
658 else if (c != (ascval = (c & 0177))) {
659 uint32_t bits, mask;
660 for (bits = 1, mask = 1; mask & 0177; mask <<= 1) {
661 if (mask & ascval)
662 bits++;
663 }
664 cp->parity |= ((bits & 1) ? 1 : 2);
665 }
666
667 switch (ascval) {
668 case 0:
669 *ptr = '\0';
670 goto quit;
671 case CR:
672 case NL:
673 *ptr = '\0';
674 cp->eol = ascval;
675 break;
676 case BS:
677 case CERASE:
678 cp->erase = ascval;
679 if (ptr > &pass[0])
680 ptr--;
681 break;
682 case CKILL:
683 cp->kill = ascval;
684 while (ptr > &pass[0])
685 ptr--;
686 break;
687 case CEOF:
688 goto quit;
689 default:
690 if ((size_t)(ptr - &pass[0]) >= (sizeof(pass) -1 )) {
691 fprintf(stderr, "sulogin: input overrun at %s\n\r", con->tty);
692 ret = (char*)0;
693 goto quit;
694 }
695 *ptr++ = ascval;
696 break;
697 }
698 }
699 quit:
700 alarm(0);
701 if (tc)
702 (void)tcsetattr(fd, TCSAFLUSH, &con->tio);
703 if (ret && *ret != '\0')
704 tcfinal(con);
705 printf("\r\n");
706 out:
707 return ret;
708 }
709
710 /*
711 * Password was OK, execute a shell.
712 */
713 static
714 void sushell(struct passwd *pwd)
715 {
716 char shell[128];
717 char home[128];
718 char *p;
719 char *sushell;
720
721 /*
722 * Set directory and shell.
723 */
724 if (chdir(pwd->pw_dir) < 0) {
725 if (chdir("/") < 0)
726 fprintf(stderr, "sulogin: change of working directory failed: %m\n\r");
727 }
728 if ((p = getenv("SUSHELL")) != NULL)
729 sushell = p;
730 else if ((p = getenv("sushell")) != NULL)
731 sushell = p;
732 else {
733 if (pwd->pw_shell[0])
734 sushell = pwd->pw_shell;
735 else
736 sushell = BINSH;
737 }
738 if ((p = strrchr(sushell, '/')) == NULL)
739 p = sushell;
740 else
741 p++;
742 snprintf(shell, sizeof(shell), profile ? "-%s" : "%s", p);
743
744 /*
745 * Set some important environment variables.
746 */
747 if (getcwd(home, sizeof(home)) == (char*)0)
748 strcpy(home, "/");
749 setenv("HOME", home, 1);
750 setenv("LOGNAME", "root", 1);
751 setenv("USER", "root", 1);
752 if (!profile)
753 setenv("SHLVL","0",1);
754
755 /*
756 * Try to execute a shell.
757 */
758 setenv("SHELL", sushell, 1);
759 signal(SIGINT, saved_sigint);
760 signal(SIGTSTP, saved_sigtstp);
761 signal(SIGQUIT, saved_sigquit);
762 signal(SIGHUP, SIG_DFL);
763 #ifdef WITH_SELINUX
764 if (is_selinux_enabled() > 0) {
765 security_context_t scon=NULL;
766 char *seuser=NULL;
767 char *level=NULL;
768 if (getseuserbyname("root", &seuser, &level) == 0)
769 if (get_default_context_with_level(seuser, level, 0, &scon) == 0) {
770 if (setexeccon(scon) != 0)
771 fprintf(stderr, "sulogin: setexeccon failed\n\r");
772 freecon(scon);
773 }
774 free(seuser);
775 free(level);
776 }
777 #endif
778 execl(sushell, shell, NULL);
779 perror(sushell);
780
781 setenv("SHELL", BINSH, 1);
782 execl(BINSH, profile ? "-sh" : "sh", NULL);
783 perror(BINSH);
784
785 /* Fall back to staticly linked shell if both the users shell
786 and /bin/sh failed to execute. */
787 setenv("SHELL", STATICSH, 1);
788 execl(STATICSH, STATICSH, NULL);
789 perror(STATICSH);
790 }
791
792 #ifdef __linux__
793 /*
794 * Make C library standard calls like ttyname(3) work.
795 */
796 static uint32_t mounts;
797 #define MNT_PROCFS 0x0001
798 #define MNT_DEVTMPFS 0x0002
799
800 static __attribute__((__noinline__))
801 void putmounts(void)
802 {
803 if (mounts & MNT_DEVTMPFS)
804 umount2("/dev", MNT_DETACH);
805 if (mounts & MNT_PROCFS)
806 umount2("/proc", MNT_DETACH);
807 }
808
809 static __attribute__((__constructor__))
810 void getmounts(void)
811 {
812 struct statfs st;
813 if (statfs("/proc", &st) == 0 && st.f_type != PROC_SUPER_MAGIC) {
814 if (mount("proc", "/proc", "proc", MS_RELATIME, NULL) == 0)
815 mounts |= MNT_PROCFS;
816 }
817 if (statfs("/dev", &st) == 0 && st.f_type != TMPFS_MAGIC) {
818 if (mount("devtmpfs", "/dev", "devtmpfs", MS_RELATIME, "mode=0755,nr_inodes=0") == 0) {
819 mounts |= MNT_DEVTMPFS;
820 (void)mknod("/dev/console", S_IFCHR|S_IRUSR|S_IWUSR, makedev(TTYAUX_MAJOR, 1));
821 if (symlink("/proc/self/fd", "/dev/fd") == 0) {
822 dovoid(symlink("fd/0", "/dev/stdin"));
823 dovoid(symlink("fd/1", "/dev/stdout"));
824 dovoid(symlink("fd/2", "/dev/stderr"));
825 }
826 }
827 }
828 if (mounts) atexit(putmounts);
829 }
830 #endif
831
832 static
833 void usage(void)
834 {
835 fprintf(stderr, "Usage: sulogin [-e] [-p] [-t timeout] [tty device]\n\r");
836 }
837
838 int main(int argc, char **argv)
839 {
840 char *tty = NULL;
841 struct passwd *pwd;
842 int c, status = 0;
843 int reconnect = 0;
844 int opt_e = 0;
845 struct console *con;
846 pid_t pid;
847
848 /*
849 * We are init. We hence need to set uo a session.
850 */
851 if ((pid = getpid()) == 1) {
852 setsid();
853 (void)ioctl(0, TIOCSCTTY, (char *)1);
854 }
855
856 /*
857 * See if we have a timeout flag.
858 */
859 opterr = 0;
860 while((c = getopt(argc, argv, "ept:")) != EOF) switch(c) {
861 case 't':
862 timeout = atoi(optarg);
863 break;
864 case 'p':
865 profile = 1;
866 break;
867 case 'e':
868 opt_e = 1;
869 break;
870 default:
871 usage();
872 /* Do not exit! */
873 break;
874 }
875
876 if (geteuid() != 0) {
877 fprintf(stderr, "sulogin: only root can run sulogin.\n\r");
878 exit(1);
879 }
880
881 saved_sigint = signal(SIGINT, SIG_IGN);
882 saved_sigquit = signal(SIGQUIT, SIG_IGN);
883 saved_sigtstp = signal(SIGTSTP, SIG_IGN);
884 saved_sighup = signal(SIGHUP, SIG_IGN);
885
886 /*
887 * See if we need to open an other tty device.
888 */
889 if (optind < argc)
890 tty = argv[optind];
891 if (!tty || *tty == '\0')
892 tty = getenv("CONSOLE");
893
894 /*
895 * Detect possible consoles, use stdin as fallback.
896 * If an optional tty is given, reconnect it to stdin.
897 */
898 reconnect = detect_consoles(tty, 0);
899
900 /*
901 * Should not happen
902 */
903 if (!consoles) {
904 if (!errno)
905 errno = ENOMEM;
906 fprintf(stderr, "sulogin: cannot open console: %m\n\r");
907 exit(1);
908 }
909
910 /*
911 * If previous stdin was not the speified tty and therefore reconnected
912 * to the specified tty also reconnect stdout and stderr.
913 */
914 if (reconnect) {
915 if (isatty(1) == 0)
916 dup2(0, 1);
917 if (isatty(2) == 0)
918 dup2(0, 2);
919 }
920
921 /*
922 * Get the root password.
923 */
924 if ((pwd = getrootpwent(opt_e)) == NULL) {
925 fprintf(stderr, "sulogin: cannot open password database!\n\r");
926 sleep(2);
927 }
928
929 /*
930 * Prompt for input on the consoles
931 */
932 for (con = consoles; con && con->id < CONMAX; con = con->next) {
933 if (con->fd >= 0) {
934 openfd |= (1<<con->fd);
935 tcinit(con);
936 continue;
937 }
938 if ((con->fd = open(con->tty, O_RDWR | O_NOCTTY | O_NONBLOCK)) < 0)
939 continue;
940 openfd |= (1<<con->fd);
941 tcinit(con);
942 }
943 con = consoles;
944 usemask = (uint32_t*)mmap(NULL, sizeof(uint32_t), PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_SHARED, -1, 0);
945
946 if (con->next == (struct console*)0)
947 goto nofork;
948
949 signal(SIGCHLD, chld_handler);
950 do {
951 switch ((con->pid = fork())) {
952 case 0:
953 signal(SIGCHLD, SIG_DFL);
954 /* fall through */
955 nofork:
956 setup(con);
957 while (1) {
958 char *passwd = pwd->pw_passwd;
959 char *answer;
960 int failed = 0, doshell = 0;
961
962 doprompt(passwd, con);
963 if ((answer = getpasswd(con)) == NULL)
964 break;
965
966 if (passwd[0] == '\0')
967 doshell++;
968 else {
969 char *cryptbuf;
970 cryptbuf = crypt(answer, passwd);
971 if (cryptbuf == NULL)
972 fprintf(stderr, "sulogin: crypt failed: %m\n\r");
973 else if (strcmp(cryptbuf, pwd->pw_passwd) == 0)
974 doshell++;
975 }
976
977 if (doshell) {
978 *usemask |= (1<<con->id);
979 sushell(pwd);
980 *usemask &= ~(1<<con->id);
981 failed++;
982 }
983
984 signal(SIGQUIT, SIG_IGN);
985 signal(SIGTSTP, SIG_IGN);
986 signal(SIGINT, SIG_IGN);
987
988 if (failed) {
989 fprintf(stderr, "sulogin: can not execute su shell.\n\r");
990 break;
991 }
992 fprintf(stderr, "Login incorrect.\n\r");
993 sleep(3);
994 }
995 if (alarm_rised) {
996 tcfinal(con);
997 fprintf(stderr, "Timed out.\n\r");
998 }
999 /*
1000 * User may pressed Control-D.
1001 */
1002 exit(0);
1003 case -1:
1004 fprintf(stderr, "sulogin: can not fork: %m\n\r");
1005 /* fall through */
1006 default:
1007 break;
1008 }
1009 } while ((con = con->next) && (con->id < CONMAX));
1010
1011 while ((pid = wait(&status))) {
1012 if (errno == ECHILD)
1013 break;
1014 if (pid < 0)
1015 continue;
1016 for (con = consoles; con && con->id < CONMAX; con = con->next) {
1017 if (con->pid == pid) {
1018 *usemask &= ~(1<<con->id);
1019 continue;
1020 }
1021 if (kill(con->pid, 0) < 0) {
1022 *usemask &= ~(1<<con->id);
1023 continue;
1024 }
1025 if (*usemask & (1<<con->id))
1026 continue;
1027 kill(con->pid, SIGHUP);
1028 usleep(5000);
1029 kill(con->pid, SIGKILL);
1030 }
1031 }
1032 signal(SIGCHLD, SIG_DFL);
1033
1034 return 0;
1035 }