/mandos/trunk

To get this branch, use:
bzr branch http://bzr.recompile.se/loggerhead/mandos/trunk
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
/*  -*- coding: utf-8 -*- */
/*
 * Usplash - Read a password from usplash and output it
 * 
 * Copyright © 2008,2009 Teddy Hogeborn
 * Copyright © 2008,2009 Björn Påhlsson
 * 
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see
 * <http://www.gnu.org/licenses/>.
 * 
 * Contact the authors at <https://www.fukt.bsnet.se/~belorn/> and
 * <https://www.fukt.bsnet.se/~teddy/>.
 */

#define _GNU_SOURCE		/* asprintf() */
#include <signal.h>		/* sig_atomic_t, struct sigaction,
				   sigemptyset(), sigaddset(), SIGINT,
				   SIGHUP, SIGTERM, sigaction(),
				   SIG_IGN, kill(), SIGKILL */
#include <stdbool.h>		/* bool, false, true */
#include <fcntl.h>		/* open(), O_WRONLY, O_RDONLY */
#include <iso646.h>		/* and, or, not*/
#include <errno.h>		/* errno, EINTR */
#include <sys/types.h>		/* size_t, ssize_t, pid_t, DIR, struct
				   dirent */
#include <stddef.h>		/* NULL */
#include <string.h>		/* strlen(), memcmp() */
#include <stdio.h>		/* asprintf(), perror(), sscanf() */
#include <unistd.h>		/* close(), write(), readlink(),
				   read(), STDOUT_FILENO, sleep(),
				   fork(), setuid(), geteuid(),
				   setsid(), chdir(), dup2(),
				   STDERR_FILENO, execv() */
#include <stdlib.h>		/* free(), EXIT_FAILURE, realloc(),
				   EXIT_SUCCESS, malloc(), _exit() */
#include <stdlib.h>		/* getenv() */
#include <dirent.h>		/* opendir(), readdir(), closedir() */
#include <sys/stat.h>		/* struct stat, lstat(), S_ISLNK */

sig_atomic_t interrupted_by_signal = 0;

static void termination_handler(__attribute__((unused))int signum){
  interrupted_by_signal = 1;
}

static bool usplash_write(const char *cmd, const char *arg){
  /* 
   * usplash_write("TIMEOUT", "15") will write "TIMEOUT 15\0"
   * usplash_write("PULSATE", NULL) will write "PULSATE\0"
   * SEE ALSO
   *         usplash_write(8)
   */
  int ret;
  int fifo_fd;
  do{
    fifo_fd = open("/dev/.initramfs/usplash_fifo", O_WRONLY);
    if(fifo_fd == -1 and (errno != EINTR or interrupted_by_signal)){
      return false;
    }
  }while(fifo_fd == -1);
  
  const char *cmd_line;
  size_t cmd_line_len;
  char *cmd_line_alloc = NULL;
  if(arg == NULL){
    cmd_line = cmd;
    cmd_line_len = strlen(cmd);
  }else{
    do{
      ret = asprintf(&cmd_line_alloc, "%s %s", cmd, arg);
      if(ret == -1 and (errno != EINTR or interrupted_by_signal)){
	int e = errno;
	close(fifo_fd);
	errno = e;
	return false;
      }
    }while(ret == -1);
    cmd_line = cmd_line_alloc;
    cmd_line_len = (size_t)ret + 1;
  }
  
  size_t written = 0;
  ssize_t sret = 0;
  while(not interrupted_by_signal and written < cmd_line_len){
    sret = write(fifo_fd, cmd_line + written,
		 cmd_line_len - written);
    if(sret == -1){
      if(errno != EINTR or interrupted_by_signal){
	int e = errno;
	close(fifo_fd);
	free(cmd_line_alloc);
	errno = e;
	return false;
      } else {
	continue;
      }
    }
    written += (size_t)sret;
  }
  free(cmd_line_alloc);
  do{
    ret = close(fifo_fd);
    if(ret == -1 and (errno != EINTR or interrupted_by_signal)){
      return false;
    }
  }while(ret == -1);
  if(interrupted_by_signal){
    return false;
  }
  return true;
}

int main(__attribute__((unused))int argc,
	 __attribute__((unused))char **argv){
  int ret = 0;
  ssize_t sret;
  bool an_error_occured = false;
  
  /* Create prompt string */
  char *prompt = NULL;
  {
    const char *const cryptsource = getenv("cryptsource");
    const char *const crypttarget = getenv("crypttarget");
    const char prompt_start[] = "Enter passphrase to unlock the disk";
    
    if(cryptsource == NULL){
      if(crypttarget == NULL){
	ret = asprintf(&prompt, "%s: ", prompt_start);
      } else {
	ret = asprintf(&prompt, "%s (%s): ", prompt_start,
		       crypttarget);
      }
    } else {
      if(crypttarget == NULL){
	ret = asprintf(&prompt, "%s %s: ", prompt_start, cryptsource);
      } else {
	ret = asprintf(&prompt, "%s %s (%s): ", prompt_start,
		       cryptsource, crypttarget);
      }
    }
    if(ret == -1){
      return EXIT_FAILURE;
    }
  }
  
  /* Find usplash process */
  pid_t usplash_pid = 0;
  char *cmdline = NULL;
  size_t cmdline_len = 0;
  const char usplash_name[] = "/sbin/usplash";
  {
    DIR *proc_dir = opendir("/proc");
    if(proc_dir == NULL){
      free(prompt);
      perror("opendir");
      return EXIT_FAILURE;
    }
    for(struct dirent *proc_ent = readdir(proc_dir);
	proc_ent != NULL;
	proc_ent = readdir(proc_dir)){
      pid_t pid;
      /* In the GNU C library, pid_t is always int */
      ret = sscanf(proc_ent->d_name, "%d", &pid);
      if(ret != 1){
	/* Not a process */
	continue;
      }
      /* Find the executable name by doing readlink() on the
	 /proc/<pid>/exe link */
      char exe_target[sizeof(usplash_name)];
      {
	/* create file name string */
	char *exe_link;
	ret = asprintf(&exe_link, "/proc/%s/exe", proc_ent->d_name);
	if(ret == -1){
	  perror("asprintf");
	  free(prompt);
	  closedir(proc_dir);
	  return EXIT_FAILURE;
	}
	
	/* Check that it refers to a symlink owned by root:root */
	struct stat exe_stat;
	ret = lstat(exe_link, &exe_stat);
	if(ret == -1){
	  if(errno == ENOENT){
	    free(exe_link);
	    continue;
	  }
	  perror("lstat");
	  free(exe_link);
	  free(prompt);
	  closedir(proc_dir);
	  return EXIT_FAILURE;
	}
	if(not S_ISLNK(exe_stat.st_mode)
	   or exe_stat.st_uid != 0
	   or exe_stat.st_gid != 0){
	  free(exe_link);
	  continue;
	}
	
	sret = readlink(exe_link, exe_target, sizeof(exe_target));
	free(exe_link);
      }
      if((sret == ((ssize_t)sizeof(exe_target)-1))
	 and (memcmp(usplash_name, exe_target,
		     sizeof(exe_target)-1) == 0)){
	usplash_pid = pid;
	/* Read and save the command line of usplash in "cmdline" */
	{
	  /* Open /proc/<pid>/cmdline  */
	  int cl_fd;
	  {
	    char *cmdline_filename;
	    ret = asprintf(&cmdline_filename, "/proc/%s/cmdline",
			   proc_ent->d_name);
	    if(ret == -1){
	      perror("asprintf");
	      free(prompt);
	      closedir(proc_dir);
	      return EXIT_FAILURE;
	    }
	    cl_fd = open(cmdline_filename, O_RDONLY);
	    if(cl_fd == -1){
	      perror("open");
	      free(cmdline_filename);
	      free(prompt);
	      closedir(proc_dir);
	      return EXIT_FAILURE;
	    }
	    free(cmdline_filename);
	  }
	  size_t cmdline_allocated = 0;
	  char *tmp;
	  const size_t blocksize = 1024;
	  do{
	    if(cmdline_len + blocksize > cmdline_allocated){
	      tmp = realloc(cmdline, cmdline_allocated + blocksize);
	      if(tmp == NULL){
		perror("realloc");
		free(cmdline);
		free(prompt);
		closedir(proc_dir);
		return EXIT_FAILURE;
	      }
	      cmdline = tmp;
	      cmdline_allocated += blocksize;
	    }
	    sret = read(cl_fd, cmdline + cmdline_len,
			cmdline_allocated - cmdline_len);
	    if(sret == -1){
	      perror("read");
	      free(cmdline);
	      free(prompt);
	      closedir(proc_dir);
	      return EXIT_FAILURE;
	    }
	    cmdline_len += (size_t)sret;
	  } while(sret != 0);
	  close(cl_fd);
	}
	break;
      }
    }
    closedir(proc_dir);
  }
  if(usplash_pid == 0){
    free(prompt);
    return EXIT_FAILURE;
  }
  
  /* Set up the signal handler */
  {
    struct sigaction old_action,
      new_action = { .sa_handler = termination_handler,
		     .sa_flags = 0 };
    sigemptyset(&new_action.sa_mask);
    sigaddset(&new_action.sa_mask, SIGINT);
    sigaddset(&new_action.sa_mask, SIGHUP);
    sigaddset(&new_action.sa_mask, SIGTERM);
    ret = sigaction(SIGINT, NULL, &old_action);
    if(ret == -1){
      perror("sigaction");
      free(prompt);
      return EXIT_FAILURE;
    }
    if(old_action.sa_handler != SIG_IGN){
      ret = sigaction(SIGINT, &new_action, NULL);
      if(ret == -1){
	perror("sigaction");
	free(prompt);
	return EXIT_FAILURE;
      }
    }
    ret = sigaction(SIGHUP, NULL, &old_action);
    if(ret == -1){
      perror("sigaction");
      free(prompt);
      return EXIT_FAILURE;
    }
    if(old_action.sa_handler != SIG_IGN){
      ret = sigaction(SIGHUP, &new_action, NULL);
      if(ret == -1){
	perror("sigaction");
	free(prompt);
	return EXIT_FAILURE;
      }
    }
    ret = sigaction(SIGTERM, NULL, &old_action);
    if(ret == -1){
      perror("sigaction");
      free(prompt);
      return EXIT_FAILURE;
    }
    if(old_action.sa_handler != SIG_IGN){
      ret = sigaction(SIGTERM, &new_action, NULL);
      if(ret == -1){
	perror("sigaction");
	free(prompt);
	return EXIT_FAILURE;
      }
    }
  }
  
  /* Write command to FIFO */
  if(not interrupted_by_signal){
    if(not usplash_write("TIMEOUT", "0")
       and (errno != EINTR)){
      perror("usplash_write");
      an_error_occured = true;
    }
  }
  if(not interrupted_by_signal and not an_error_occured){
    if(not usplash_write("INPUTQUIET", prompt)
       and (errno != EINTR)){
      perror("usplash_write");
      an_error_occured = true;
    }
  }
  free(prompt);
  
  /* This is not really a loop; while() is used to be able to "break"
     out of it; those breaks are marked "Big" */
  while(not interrupted_by_signal and not an_error_occured){
    char *buf = NULL;
    size_t buf_len = 0;
    
    /* Open FIFO */
    int fifo_fd;
    do{
      fifo_fd = open("/dev/.initramfs/usplash_outfifo", O_RDONLY);
      if(fifo_fd == -1){
	if(errno != EINTR){
	  perror("open");
	  an_error_occured = true;
	  break;
	}
	if(interrupted_by_signal){
	  break;
	}
      }
    }while(fifo_fd == -1);
    if(interrupted_by_signal or an_error_occured){
      break;			/* Big */
    }
    
    /* Read from FIFO */
    size_t buf_allocated = 0;
    const size_t blocksize = 1024;
    do{
      if(buf_len + blocksize > buf_allocated){
	char *tmp = realloc(buf, buf_allocated + blocksize);
	if(tmp == NULL){
	  perror("realloc");
	  an_error_occured = true;
	  break;
	}
	buf = tmp;
	buf_allocated += blocksize;
      }
      do{
	sret = read(fifo_fd, buf + buf_len, buf_allocated - buf_len);
	if(sret == -1){
	  if(errno != EINTR){
	    perror("read");
	    an_error_occured = true;
	    break;
	  }
	  if(interrupted_by_signal){
	    break;
	  }
	}
      }while(sret == -1);
      if(interrupted_by_signal or an_error_occured){
	break;
      }
      
      buf_len += (size_t)sret;
    }while(sret != 0);
    close(fifo_fd);
    if(interrupted_by_signal or an_error_occured){
      break;			/* Big */
    }
    
    if(not usplash_write("TIMEOUT", "15")
       and (errno != EINTR)){
	perror("usplash_write");
	an_error_occured = true;
    }
    if(interrupted_by_signal or an_error_occured){
      break;			/* Big */
    }
    
    /* Print password to stdout */
    size_t written = 0;
    while(written < buf_len){
      do{
	sret = write(STDOUT_FILENO, buf + written, buf_len - written);
	if(sret == -1){
	  if(errno != EINTR){
	    perror("write");
	    an_error_occured = true;
	    break;
	  }
	  if(interrupted_by_signal){
	    break;
	  }
	}
      }while(sret == -1);
      if(interrupted_by_signal or an_error_occured){
	break;
      }
      written += (size_t)sret;
    }
    free(buf);
    if(not interrupted_by_signal and not an_error_occured){
      free(cmdline);
      return EXIT_SUCCESS;
    }
    break;			/* Big */
  }				/* end of non-loop while() */
  
  /* If we got here, an error or interrupt must have happened */
  
  /* Create argc and argv for new usplash*/
  int cmdline_argc = 0;
  char **cmdline_argv = malloc(sizeof(char *));
  {
    size_t position = 0;
    while(position < cmdline_len){
      char **tmp = realloc(cmdline_argv,
			   (sizeof(char *)
			    * (size_t)(cmdline_argc + 2)));
      if(tmp == NULL){
	perror("realloc");
	free(cmdline_argv);
	return EXIT_FAILURE;
      }
      cmdline_argv = tmp;
      cmdline_argv[cmdline_argc] = cmdline + position;
      cmdline_argc++;
      position += strlen(cmdline + position) + 1;
    }
    cmdline_argv[cmdline_argc] = NULL;
  }
  /* Kill old usplash */
  kill(usplash_pid, SIGTERM);
  sleep(2);
  while(kill(usplash_pid, 0) == 0){
    kill(usplash_pid, SIGKILL);
    sleep(1);
  }
  pid_t new_usplash_pid = fork();
  if(new_usplash_pid == 0){
    /* Child; will become new usplash process */
    
    /* Make the effective user ID (root) the only user ID instead of
       the real user ID (mandos) */
    ret = setuid(geteuid());
    if(ret == -1){
      perror("setuid");
    }
    
    setsid();
    ret = chdir("/");
/*     if(fork() != 0){ */
/*       _exit(EXIT_SUCCESS); */
/*     } */
    ret = dup2(STDERR_FILENO, STDOUT_FILENO); /* replace our stdout */
    if(ret == -1){
      perror("dup2");
      _exit(EXIT_FAILURE);
    }
    
    execv(usplash_name, cmdline_argv);
    if(not interrupted_by_signal){
      perror("execv");
    }
    free(cmdline);
    free(cmdline_argv);
    _exit(EXIT_FAILURE);
  }
  free(cmdline);
  free(cmdline_argv);
  sleep(2);
  if(not usplash_write("PULSATE", NULL)
     and (errno != EINTR)){
    perror("usplash_write");
  }
  
  return EXIT_FAILURE;
}