summaryrefslogtreecommitdiffstats
path: root/g10/exec.c
blob: 1baa49f0206b716467a979f2a3f304033a4c97ec (plain)
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
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
/* exec.c - generic call-a-program code
 * Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG 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.
 *
 * GnuPG 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 <https://www.gnu.org/licenses/>.
 */

/*
   FIXME: We should replace most code in this module by our
   spawn implementation from common/exechelp.c.
 */


#include <config.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#ifndef EXEC_TEMPFILE_ONLY
#include <sys/wait.h>
#endif
#ifdef HAVE_DOSISH_SYSTEM
# ifdef HAVE_WINSOCK2_H
#  include <winsock2.h>
# endif
# include <windows.h>
#endif
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include "gpg.h"
#include "options.h"
#include "../common/i18n.h"
#include "../common/iobuf.h"
#include "../common/util.h"
#include "../common/membuf.h"
#include "../common/sysutils.h"
#include "exec.h"

#ifdef NO_EXEC
int
exec_write(struct exec_info **info,const char *program,
	       const char *args_in,const char *name,int writeonly,int binary)
{
  log_error(_("no remote program execution supported\n"));
  return GPG_ERR_GENERAL;
}

int
exec_read(struct exec_info *info) { return GPG_ERR_GENERAL; }
int
exec_finish(struct exec_info *info) { return GPG_ERR_GENERAL; }
int
set_exec_path(const char *path) { return GPG_ERR_GENERAL; }

#else /* ! NO_EXEC */

#if defined (_WIN32)
/* This is a nicer system() for windows that waits for programs to
   return before returning control to the caller.  I hate helpful
   computers. */
static int
w32_system(const char *command)
{
  if (!strncmp (command, "!ShellExecute ", 14))
    {
      SHELLEXECUTEINFOW see;
      wchar_t *wname;
      int waitms;

      command = command + 14;
      while (spacep (command))
        command++;
      waitms = atoi (command);
      if (waitms < 0)
        waitms = 0;
      else if (waitms > 60*1000)
        waitms = 60000;
      while (*command && !spacep (command))
        command++;
      while (spacep (command))
        command++;

      wname = utf8_to_wchar (command);
      if (!wname)
        return -1;

      memset (&see, 0, sizeof see);
      see.cbSize = sizeof see;
      see.fMask = (SEE_MASK_NOCLOSEPROCESS
                   | SEE_MASK_NOASYNC
                   | SEE_MASK_FLAG_NO_UI
                   | SEE_MASK_NO_CONSOLE);
      see.lpVerb = L"open";
      see.lpFile = (LPCWSTR)wname;
      see.nShow = SW_SHOW;

      if (DBG_EXTPROG)
        log_debug ("running ShellExecuteEx(open,'%s')\n", command);
      if (!ShellExecuteExW (&see))
        {
          if (DBG_EXTPROG)
            log_debug ("ShellExecuteEx failed: rc=%d\n", (int)GetLastError ());
          xfree (wname);
          return -1;
        }
      if (DBG_EXTPROG)
        log_debug ("ShellExecuteEx succeeded (hProcess=%p,hInstApp=%d)\n",
                   see.hProcess, (int)see.hInstApp);

      if (!see.hProcess)
        {
          gnupg_usleep (waitms*1000);
          if (DBG_EXTPROG)
            log_debug ("ShellExecuteEx ready (wait=%dms)\n", waitms);
        }
      else
        {
          WaitForSingleObject (see.hProcess, INFINITE);
          if (DBG_EXTPROG)
            log_debug ("ShellExecuteEx ready\n");
        }
      CloseHandle (see.hProcess);

      xfree (wname);
    }
  else
    {
      char *string;
      PROCESS_INFORMATION pi;
      STARTUPINFO si;

      /* We must use a copy of the command as CreateProcess modifies
       * this argument. */
      string = xstrdup (command);

      memset (&pi, 0, sizeof(pi));
      memset (&si, 0, sizeof(si));
      si.cb = sizeof (si);

      if (!CreateProcess (NULL, string, NULL, NULL, FALSE,
                          DETACHED_PROCESS,
                          NULL, NULL, &si, &pi))
        return -1;

      /* Wait for the child to exit */
      WaitForSingleObject (pi.hProcess, INFINITE);

      CloseHandle (pi.hProcess);
      CloseHandle (pi.hThread);
      xfree (string);
    }

  return 0;
}
#endif /*_W32*/


/* Replaces current $PATH */
int
set_exec_path(const char *path)
{
#ifdef HAVE_W32CE_SYSTEM
#warning Change this code to use common/exechelp.c
#else
  char *p;

  p=xmalloc(5+strlen(path)+1);
  strcpy(p,"PATH=");
  strcat(p,path);

  if(DBG_EXTPROG)
    log_debug("set_exec_path: %s\n",p);

  /* Notice that path is never freed.  That is intentional due to the
     way putenv() works.  This leaks a few bytes if we call
     set_exec_path multiple times. */

  if(putenv(p)!=0)
    return GPG_ERR_GENERAL;
  else
    return 0;
#endif
}

/* Makes a temp directory and filenames */
static int
make_tempdir(struct exec_info *info)
{
  char *tmp=opt.temp_dir,*namein=info->name,*nameout;

  if(!namein)
    namein=info->flags.binary?"tempin" EXTSEP_S "bin":"tempin" EXTSEP_S "txt";

  nameout=info->flags.binary?"tempout" EXTSEP_S "bin":"tempout" EXTSEP_S "txt";

  /* Make up the temp dir and files in case we need them */

  if(tmp==NULL)
    {
#if defined (_WIN32)
      int err;

      tmp=xmalloc(MAX_PATH+2);
      err=GetTempPath(MAX_PATH+1,tmp);
      if(err==0 || err>MAX_PATH+1)
	strcpy(tmp,"c:\\windows\\temp");
      else
	{
	  int len=strlen(tmp);

	  /* GetTempPath may return with \ on the end */
	  while(len>0 && tmp[len-1]=='\\')
	    {
	      tmp[len-1]='\0';
	      len--;
	    }
	}
#else /* More unixish systems */
      tmp=getenv("TMPDIR");
      if(tmp==NULL)
	{
	  tmp=getenv("TMP");
	  if(tmp==NULL)
	    {
#ifdef __riscos__
	      tmp="<Wimp$ScrapDir>.GnuPG";
	      mkdir(tmp,0700); /* Error checks occur later on */
#else
	      tmp="/tmp";
#endif
	    }
	}
#endif
    }

  info->tempdir=xmalloc(strlen(tmp)+strlen(DIRSEP_S)+10+1);

  sprintf(info->tempdir,"%s" DIRSEP_S "gpg-XXXXXX",tmp);

#if defined (_WIN32)
  xfree(tmp);
#endif

  if (!gnupg_mkdtemp(info->tempdir))
    log_error(_("can't create directory '%s': %s\n"),
	      info->tempdir,strerror(errno));
  else
    {
      info->flags.madedir=1;

      info->tempfile_in=xmalloc(strlen(info->tempdir)+
				strlen(DIRSEP_S)+strlen(namein)+1);
      sprintf(info->tempfile_in,"%s" DIRSEP_S "%s",info->tempdir,namein);

      if(!info->flags.writeonly)
	{
	  info->tempfile_out=xmalloc(strlen(info->tempdir)+
				     strlen(DIRSEP_S)+strlen(nameout)+1);
	  sprintf(info->tempfile_out,"%s" DIRSEP_S "%s",info->tempdir,nameout);
	}
    }

  return info->flags.madedir? 0 : GPG_ERR_GENERAL;
}

/* Expands %i and %o in the args to the full temp files within the
   temp directory. */
static int
expand_args(struct exec_info *info,const char *args_in)
{
  const char *ch = args_in;
  membuf_t command;

  info->flags.use_temp_files=0;
  info->flags.keep_temp_files=0;

  if(DBG_EXTPROG)
    log_debug("expanding string \"%s\"\n",args_in);

  init_membuf (&command, 100);

  while(*ch!='\0')
    {
      if(*ch=='%')
	{
	  char *append=NULL;

	  ch++;

	  switch(*ch)
	    {
	    case 'O':
	      info->flags.keep_temp_files=1;
	      /* fall through */

	    case 'o': /* out */
	      if(!info->flags.madedir)
		{
		  if(make_tempdir(info))
		    goto fail;
		}
	      append=info->tempfile_out;
	      info->flags.use_temp_files=1;
	      break;

	    case 'I':
	      info->flags.keep_temp_files=1;
	      /* fall through */

	    case 'i': /* in */
	      if(!info->flags.madedir)
		{
		  if(make_tempdir(info))
		    goto fail;
		}
	      append=info->tempfile_in;
	      info->flags.use_temp_files=1;
	      break;

	    case '%':
	      append="%";
	      break;
	    }

	  if(append)
            put_membuf_str (&command, append);
	}
      else
        put_membuf (&command, ch, 1);

      ch++;
    }

  put_membuf (&command, "", 1);  /* Terminate string.  */

  info->command = get_membuf (&command, NULL);
  if (!info->command)
    return gpg_error_from_syserror ();

  if(DBG_EXTPROG)
    log_debug("args expanded to \"%s\", use %u, keep %u\n",info->command,
	      info->flags.use_temp_files,info->flags.keep_temp_files);

  return 0;

 fail:
  xfree (get_membuf (&command, NULL));
  return GPG_ERR_GENERAL;
}

/* Either handles the tempfile creation, or the fork/exec.  If it
   returns ok, then info->tochild is a FILE * that can be written to.
   The rules are: if there are no args, then it's a fork/exec/pipe.
   If there are args, but no tempfiles, then it's a fork/exec/pipe via
   shell -c.  If there are tempfiles, then it's a system. */

int
exec_write(struct exec_info **info,const char *program,
           const char *args_in,const char *name,int writeonly,int binary)
{
  int ret = GPG_ERR_GENERAL;

  if(opt.exec_disable && !opt.no_perm_warn)
    {
      log_info(_("external program calls are disabled due to unsafe "
		 "options file permissions\n"));

      return ret;
    }

#if defined(HAVE_GETUID) && defined(HAVE_GETEUID)
  /* There should be no way to get to this spot while still carrying
     setuid privs.  Just in case, bomb out if we are. */
  if ( getuid () != geteuid ())
    BUG ();
#endif

  if(program==NULL && args_in==NULL)
    BUG();

  *info=xmalloc_clear(sizeof(struct exec_info));

  if(name)
    (*info)->name=xstrdup(name);
  (*info)->flags.binary=binary;
  (*info)->flags.writeonly=writeonly;

  /* Expand the args, if any */
  if(args_in && expand_args(*info,args_in))
    goto fail;

#ifdef EXEC_TEMPFILE_ONLY
  if(!(*info)->flags.use_temp_files)
    {
      log_error(_("this platform requires temporary files when calling"
		  " external programs\n"));
      goto fail;
    }

#else /* !EXEC_TEMPFILE_ONLY */

  /* If there are no args, or there are args, but no temp files, we
     can use fork/exec/pipe */
  if(args_in==NULL || (*info)->flags.use_temp_files==0)
    {
      int to[2],from[2];

      if(pipe(to)==-1)
	goto fail;

      if(pipe(from)==-1)
	{
	  close(to[0]);
	  close(to[1]);
	  goto fail;
	}

      if(((*info)->child=fork())==-1)
	{
	  close(to[0]);
	  close(to[1]);
	  close(from[0]);
	  close(from[1]);
	  goto fail;
	}

      if((*info)->child==0)
	{
	  char *shell=getenv("SHELL");

	  if(shell==NULL)
	    shell="/bin/sh";

	  /* I'm the child */

	  /* If the program isn't going to respond back, they get to
             keep their stdout/stderr */
	  if(!(*info)->flags.writeonly)
	    {
	      /* implied close of STDERR */
	      if(dup2(STDOUT_FILENO,STDERR_FILENO)==-1)
		_exit(1);

	      /* implied close of STDOUT */
	      close(from[0]);
	      if(dup2(from[1],STDOUT_FILENO)==-1)
		_exit(1);
	    }

	  /* implied close of STDIN */
	  close(to[1]);
	  if(dup2(to[0],STDIN_FILENO)==-1)
	    _exit(1);

	  if(args_in==NULL)
	    {
	      if(DBG_EXTPROG)
		log_debug("execlp: %s\n",program);

	      execlp(program,program,(void *)NULL);
	    }
	  else
	    {
	      if(DBG_EXTPROG)
		log_debug("execlp: %s -c %s\n",shell,(*info)->command);

	      execlp(shell,shell,"-c",(*info)->command,(void *)NULL);
	    }

	  /* If we get this far the exec failed.  Clean up and return. */

	  if(args_in==NULL)
	    log_error(_("unable to execute program '%s': %s\n"),
		      program,strerror(errno));
	  else
	    log_error(_("unable to execute shell '%s': %s\n"),
		      shell,strerror(errno));

	  /* This mimics the POSIX sh behavior - 127 means "not found"
             from the shell. */
	  if(errno==ENOENT)
	    _exit(127);

	  _exit(1);
	}

      /* I'm the parent */

      close(to[0]);

      (*info)->tochild=fdopen(to[1],binary?"wb":"w");
      if((*info)->tochild==NULL)
	{
          ret = gpg_error_from_syserror ();
	  close(to[1]);
	  goto fail;
	}

      close(from[1]);

      (*info)->fromchild=iobuf_fdopen(from[0],"r");
      if((*info)->fromchild==NULL)
	{
          ret = gpg_error_from_syserror ();
	  close(from[0]);
	  goto fail;
	}

      /* fd iobufs are cached! */
      iobuf_ioctl((*info)->fromchild, IOBUF_IOCTL_NO_CACHE, 1, NULL);

      return 0;
    }
#endif /* !EXEC_TEMPFILE_ONLY */

  if(DBG_EXTPROG)
    log_debug("using temp file '%s'\n",(*info)->tempfile_in);

  /* It's not fork/exec/pipe, so create a temp file */
  if( is_secured_filename ((*info)->tempfile_in) )
    {
      (*info)->tochild = NULL;
      gpg_err_set_errno (EPERM);
    }
  else
    (*info)->tochild = gnupg_fopen ((*info)->tempfile_in,binary?"wb":"w");
  if((*info)->tochild==NULL)
    {
      ret = gpg_error_from_syserror ();
      log_error(_("can't create '%s': %s\n"),
		(*info)->tempfile_in,strerror(errno));
      goto fail;
    }

  ret=0;

 fail:
  if (ret)
    {
      xfree (*info);
      *info = NULL;
    }
  return ret;
}

int
exec_read(struct exec_info *info)
{
  int ret = GPG_ERR_GENERAL;

  fclose(info->tochild);
  info->tochild=NULL;

  if(info->flags.use_temp_files)
    {
      if(DBG_EXTPROG)
	log_debug ("running command: %s\n",info->command);

#if defined (_WIN32)
      info->progreturn=w32_system(info->command);
#else
      info->progreturn=system(info->command);
#endif

      if(info->progreturn==-1)
	{
	  log_error(_("system error while calling external program: %s\n"),
		    strerror(errno));
	  info->progreturn=127;
	  goto fail;
	}

#if defined(WIFEXITED) && defined(WEXITSTATUS)
      if(WIFEXITED(info->progreturn))
	info->progreturn=WEXITSTATUS(info->progreturn);
      else
	{
	  log_error(_("unnatural exit of external program\n"));
	  info->progreturn=127;
	  goto fail;
	}
#else
      /* If we don't have the macros, do the best we can. */
      info->progreturn = (info->progreturn & 0xff00) >> 8;
#endif

      /* 127 is the magic value returned from system() to indicate
         that the shell could not be executed, or from /bin/sh to
         indicate that the program could not be executed. */

      if(info->progreturn==127)
	{
	  log_error(_("unable to execute external program\n"));
	  goto fail;
	}

      if(!info->flags.writeonly)
	{
	  info->fromchild=iobuf_open(info->tempfile_out);
          if (info->fromchild
              && is_secured_file (iobuf_get_fd (info->fromchild)))
            {
              iobuf_close (info->fromchild);
              info->fromchild = NULL;
              gpg_err_set_errno (EPERM);
            }
	  if(info->fromchild==NULL)
	    {
              ret = gpg_error_from_syserror ();
	      log_error(_("unable to read external program response: %s\n"),
			strerror(errno));
	      goto fail;
	    }

	  /* Do not cache this iobuf on close */
	  iobuf_ioctl(info->fromchild, IOBUF_IOCTL_NO_CACHE, 1, NULL);
	}
    }

  ret=0;

 fail:
  return ret;
}

int
exec_finish(struct exec_info *info)
{
  int ret=info->progreturn;

  if(info->fromchild)
    iobuf_close(info->fromchild);

  if(info->tochild)
    fclose(info->tochild);

#ifndef EXEC_TEMPFILE_ONLY
  if(info->child>0)
    {
      if(waitpid(info->child,&info->progreturn,0)!=0 &&
	 WIFEXITED(info->progreturn))
	ret=WEXITSTATUS(info->progreturn);
      else
	{
	  log_error(_("unnatural exit of external program\n"));
	  ret=127;
	}
    }
#endif

  if(info->flags.madedir && !info->flags.keep_temp_files)
    {
      if(info->tempfile_in)
	{
	  if(unlink(info->tempfile_in)==-1)
	    log_info(_("WARNING: unable to remove tempfile (%s) '%s': %s\n"),
		     "in",info->tempfile_in,strerror(errno));
	}

      if(info->tempfile_out)
	{
	  if(unlink(info->tempfile_out)==-1)
	    log_info(_("WARNING: unable to remove tempfile (%s) '%s': %s\n"),
		     "out",info->tempfile_out,strerror(errno));
	}

      if(rmdir(info->tempdir)==-1)
	log_info(_("WARNING: unable to remove temp directory '%s': %s\n"),
		 info->tempdir,strerror(errno));
    }

  xfree(info->command);
  xfree(info->name);
  xfree(info->tempdir);
  xfree(info->tempfile_in);
  xfree(info->tempfile_out);
  xfree(info);

  return ret;
}
#endif /* ! NO_EXEC */