src/pinentry.c

   1 /*
   2     Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
   3     Ben Kibbey <bjk@luxsci.net>
   4
   5     This file is part of libpwmd.
   6
   7     Libpwmd is free software: you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation, either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     Libpwmd is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License
  18     along with Libpwmd.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20 #ifdef HAVE_CONFIG_H
  21 #include <config.h>
  22 #endif
  23
  24 #include <sys/types.h>
  25 #include <signal.h>
  26 #include <errno.h>
  27 #include <stdlib.h>
  28 #include <limits.h>
  29
  30 #ifdef HAVE_STRING_H
  31 #include <string.h>
  32 #endif
  33
  34 #include "pinentry.h"
  35 #include "misc.h"
  36
  37 #ifdef WITH_QUALITY
  38 #include <crack.h>
  39 #endif
  40
  41 static pwm_t *gpwm;
  42 static int gelapsed, gtimeout;
  43 static gpg_error_t grc;
  44
  45 static gpg_error_t set_pinentry_strings (pwm_t * pwm, pwmd_pinentry_t which);
  46
  47 static gpg_error_t
  48 launch_pinentry (pwm_t * pwm)
  49 {
  50   int rc;
  51   assuan_context_t ctx;
  52   int child_list[] = { -1 };
  53   const char *argv[10];
  54   const char **p = argv;
  55   static struct assuan_malloc_hooks mhooks = {
  56     pwmd_malloc, pwmd_realloc, pwmd_free
  57   };
  58
  59   update_pinentry_settings (pwm);
  60   if (!pwm->pinentry_display && !pwm->pinentry_tty)
  61     return GPG_ERR_ENOTTY;
  62
  63   *p++ = "pinentry";
  64   *p++ = pwm->pinentry_display ? "--display" : "--ttyname";
  65   *p++ = pwm->pinentry_display ? pwm->pinentry_display : pwm->pinentry_tty;
  66
  67   if (pwm->pinentry_lcctype)
  68     {
  69       *p++ = "--lc-ctype";
  70       *p++ = pwm->pinentry_lcctype;
  71     }
  72
  73   if (pwm->pinentry_lcmessages)
  74     {
  75       *p++ = "--lc-messages";
  76       *p++ = pwm->pinentry_lcmessages;
  77     }
  78
  79   *p = NULL;
  80
  81   if (!pwm->pinentry_display)
  82     {
  83       *p++ = "--ttytype";
  84       *p++ = pwm->pinentry_term ? pwm->pinentry_term : getenv ("TERM");
  85       *p = NULL;
  86     }
  87
  88   rc = assuan_new_ext (&ctx, GPG_ERR_SOURCE_PINENTRY, &mhooks, NULL, NULL);
  89   if (rc)
  90     return rc;
  91
  92   rc = assuan_pipe_connect (ctx,
  93                             pwm->pinentry_path ? pwm->
  94                             pinentry_path : PINENTRY_PATH, argv, child_list,
  95                             NULL, NULL, 0);
  96   if (rc)
  97     {
  98       assuan_release (ctx);
  99       return rc;
 100     }
 101
 102   pwm->pinentry_pid = assuan_get_pid (ctx);
 103   pwm->pctx = ctx;
 104   rc = set_pinentry_strings (pwm, 0);
 105   if (rc)
 106     _pinentry_disconnect (pwm);
 107
 108   return rc;
 109 }
 110
 111 static gpg_error_t
 112 pinentry_command (pwm_t * pwm, char **result, size_t * len, const char *cmd)
 113 {
 114   if (len)
 115     *len = 0;
 116
 117   if (result)
 118     *result = NULL;
 119
 120   if (!pwm->pctx)
 121     {
 122       gpg_error_t rc = launch_pinentry (pwm);
 123
 124       if (rc)
 125         return rc;
 126     }
 127
 128   return _assuan_command (pwm, pwm->pctx, result, len, cmd);
 129 }
 130
 131 #ifdef WITH_QUALITY
 132 static gpg_error_t
 133 quality_cb (void *data, const char *line)
 134 {
 135   pwm_t *pwm = data;
 136   int score = 0;
 137   char buf[5];
 138   const char *tmp;
 139
 140   if (strncmp (line, "QUALITY ", 8))
 141     return GPG_ERR_INV_ARG;
 142
 143   if (!(tmp = FascistCheck (line + 8, CRACKLIB_DICT)))
 144     return assuan_send_data (pwm->pctx, "100", 3);
 145
 146   if (!strcmp (tmp, N_("it is WAY too short")))
 147     score = 10;
 148   else if (!strcmp (tmp, N_("it is too short")))
 149     score = 20;
 150   else if (!strcmp (tmp, N_("it is all whitespace")))
 151     score = 25;
 152   else if (!strcmp (tmp, N_("it is based on your username")))
 153     score = 30;
 154   else
 155     if (!strcmp (tmp, N_("it does not contain enough DIFFERENT characters")))
 156     score = 35;
 157   else if (!strcmp (tmp, N_("it is based on a dictionary word")))
 158     score = 40;
 159   else if (!strcmp (tmp, N_("it is based upon your password entry")))
 160     score = 50;
 161   else if (!strcmp (tmp, N_("it's derived from your password entry")))
 162     score = 50;
 163   else if (!strcmp (tmp, N_("it is derived from your password entry")))
 164     score = 50;
 165   else if (!strcmp (tmp, N_("it is based on a (reversed) dictionary word")))
 166     score = 60;
 167   else if (!strcmp (tmp, N_("it is derivable from your password entry")))
 168     score = 70;
 169   else if (!strcmp (tmp, N_("it's derivable from your password entry")))
 170     score = 70;
 171   else if (!strcmp (tmp, N_("it looks like a National Insurance number.")))
 172     score = 80;
 173   else if (!strcmp (tmp, N_("it is too simplistic/systematic")))
 174     score = 90;
 175   else
 176     score = 0;
 177
 178   snprintf (buf, sizeof (buf), "%i", score);
 179   return assuan_send_data (pwm->pctx, buf, strlen (buf));
 180 }
 181 #endif
 182
 183 static gpg_error_t
 184 set_pinentry_strings (pwm_t * pwm, pwmd_pinentry_t which)
 185 {
 186   char *tmp, *desc = NULL;
 187   gpg_error_t rc;
 188
 189   if (which != PWMD_PINENTRY_USER)
 190     {
 191       rc = pinentry_command (pwm, NULL, NULL, "SETERROR ");
 192       if (rc)
 193         return rc;
 194     }
 195
 196   tmp = pwmd_malloc (ASSUAN_LINELENGTH + 1);
 197   if (!tmp)
 198     return gpg_error_from_errno (ENOMEM);
 199
 200   if (!pwm->pinentry_prompt)
 201     {
 202       pwm->pinentry_prompt = pwmd_strdup (N_("Passphrase:"));
 203       if (!pwm->pinentry_prompt)
 204         {
 205           pwmd_free (tmp);
 206           return GPG_ERR_ENOMEM;
 207         }
 208     }
 209
 210   if (!pwm->pinentry_desc)
 211     {
 212       if (which == PWMD_PINENTRY_OPEN || which == PWMD_PINENTRY_OPEN_FAILED)
 213         desc =
 214           pwmd_strdup_printf (N_
 215                               ("A passphrase is required to unlock the secret key for the encrypted data file \"%s\". Please enter the passphrase below."),
 216                               pwm->filename);
 217       else if (which == PWMD_PINENTRY_SAVE
 218                || which == PWMD_PINENTRY_SAVE_FAILED)
 219         desc =
 220           pwmd_strdup_printf (N_
 221                               ("Please enter the passphrase to use to encrypt the data file \"%s\"."),
 222                               pwm->filename);
 223       else if (which == PWMD_PINENTRY_SAVE_CONFIRM)
 224         desc =
 225           pwmd_strdup_printf (N_
 226                               ("Please re-enter the passphrase for confirmation."),
 227                               pwm->filename);
 228
 229       if (!desc)
 230         {
 231           pwmd_free (tmp);
 232           return GPG_ERR_ENOMEM;
 233         }
 234     }
 235
 236   if (pwm->pinentry_desc)
 237     desc = pwm->pinentry_desc;
 238
 239   if (which == PWMD_PINENTRY_USER)
 240     {
 241       snprintf (tmp, ASSUAN_LINELENGTH, "SETERROR %s",
 242                 pwm->pinentry_error ? pwm->pinentry_error : "");
 243       rc = pinentry_command (pwm, NULL, NULL, tmp);
 244       if (rc)
 245         {
 246           pwmd_free (tmp);
 247           return rc;
 248         }
 249
 250       snprintf (tmp, ASSUAN_LINELENGTH, "SETDESC %s",
 251                 pwm->pinentry_desc ? pwm->pinentry_desc : "");
 252     }
 253   else
 254     {
 255       if (which == PWMD_PINENTRY_SAVE_FAILED
 256           || which == PWMD_PINENTRY_OPEN_FAILED)
 257         {
 258           if (which == PWMD_PINENTRY_SAVE_FAILED)
 259             snprintf (tmp, ASSUAN_LINELENGTH, "SETERROR %s",
 260                       N_("Passphrases do not match, try again."));
 261           else
 262             {
 263               if (pwm->pinentry_tries)
 264                 {
 265                   strcpy (tmp, "SETERROR ");
 266                   snprintf (tmp + strlen ("SETERROR "), ASSUAN_LINELENGTH,
 267                             N_("Bad passphrase (try %i of %i)"),
 268                             pwm->pinentry_try + 1, pwm->pinentry_tries);
 269                 }
 270               else
 271                 snprintf (tmp, ASSUAN_LINELENGTH, "SETERROR %s",
 272                           N_("Bad passphrase, try again"));
 273             }
 274
 275           rc = pinentry_command (pwm, NULL, NULL, tmp);
 276           if (rc)
 277             {
 278               pwmd_free (tmp);
 279               return rc;
 280             }
 281         }
 282
 283       snprintf (tmp, ASSUAN_LINELENGTH, "SETDESC %s", desc);
 284
 285       if (pwm->pinentry_desc != desc)
 286         pwmd_free (desc);
 287     }
 288
 289   rc = pinentry_command (pwm, NULL, NULL, tmp);
 290   if (rc)
 291     {
 292       pwmd_free (tmp);
 293       return rc;
 294     }
 295
 296   snprintf (tmp, ASSUAN_LINELENGTH, "SETPROMPT %s", pwm->pinentry_prompt);
 297   rc = pinentry_command (pwm, NULL, NULL, tmp);
 298   pwmd_free (tmp);
 299
 300 #ifdef WITH_QUALITY
 301   if (!rc && (which == PWMD_PINENTRY_SAVE ||
 302               which == PWMD_PINENTRY_SAVE_FAILED))
 303     {
 304       rc = pinentry_command (pwm, NULL, NULL, "SETQUALITYBAR");
 305       if (!rc)
 306         {
 307           pwm->_inquire_func = quality_cb;
 308           pwm->_inquire_data = pwm;
 309         }
 310     }
 311 #endif
 312
 313   return rc;
 314 }
 315
 316 static gpg_error_t
 317 terminate_pinentry (pwm_t * pwm)
 318 {
 319   pid_t pid;
 320
 321   if (!pwm || pwm->pinentry_pid == -1)
 322     return GPG_ERR_INV_ARG;
 323
 324   pid = pwm->pinentry_pid;
 325   pwm->pinentry_pid = -1;
 326
 327   if (kill (pid, 0) == 0)
 328     {
 329       if (kill (pid, SIGTERM) == -1)
 330         {
 331           if (kill (pid, SIGKILL) == -1)
 332             return gpg_error_from_errno (errno);
 333         }
 334     }
 335   else
 336     return gpg_error_from_errno (errno);
 337
 338   return 0;
 339 }
 340
 341 void
 342 _pinentry_disconnect (pwm_t * pwm)
 343 {
 344   if (pwm->pctx)
 345     assuan_release (pwm->pctx);
 346
 347   pwm->pctx = NULL;
 348   pwm->pinentry_pid = -1;
 349 }
 350
 351 /*
 352  * Only called from a child process.
 353  */
 354 static void
 355 catchsig (int sig)
 356 {
 357   switch (sig)
 358     {
 359     case SIGALRM:
 360       if (++gelapsed >= gtimeout)
 361         {
 362           terminate_pinentry (gpwm);
 363           grc = gpg_err_make (GPG_ERR_SOURCE_PINENTRY, GPG_ERR_CANCELED);
 364         }
 365       else
 366         alarm (1);
 367       break;
 368     default:
 369       break;
 370     }
 371 }
 372
 373 gpg_error_t
 374 _getpin (pwm_t * pwm, char **result, size_t * len, pwmd_pinentry_t which)
 375 {
 376   grc = 0;
 377   gpg_error_t rc = set_pinentry_strings (pwm, which);
 378
 379   if (rc)
 380     {
 381       _pinentry_disconnect (pwm);
 382       return rc;
 383     }
 384
 385   if (gtimeout)
 386     {
 387       signal (SIGALRM, catchsig);
 388       alarm (1);
 389     }
 390
 391   rc = pinentry_command (pwm, result, len,
 392                          which == PWMD_PINENTRY_CONFIRM ? "CONFIRM" : "GETPIN");
 393
 394   /*
 395    * Since there was input cancel any timeout setting.
 396    */
 397   alarm (0);
 398   signal (SIGALRM, SIG_DFL);
 399
 400   if (rc)
 401     {
 402       _pinentry_disconnect (pwm);
 403
 404       /* This lets PWMD_OPTION_PINENTRY_TIMEOUT work. Note that it is not
 405        * thread safe do to the global variables. */
 406       if (gpg_err_code (rc) == GPG_ERR_EOF)
 407         rc = GPG_ERR_CANCELED;
 408     }
 409   else if (which != PWMD_PINENTRY_CONFIRM && len && result)
 410     {
 411       if (*len)
 412         *len = strlen (*result);        // remove the null byte
 413       else
 414         {
 415           /* pwmd allows for an empty passphrase when not using gpg-agent. */
 416           *result = pwmd_malloc (1);
 417           *(*result) = 0;
 418           *len = 1;
 419         }
 420     }
 421
 422   return rc;
 423 }
 424
 425 gpg_error_t
 426 _pwmd_getpin (pwm_t * pwm, const char *filename, char **result,
 427               size_t * len, pwmd_pinentry_t which)
 428 {
 429   gpg_error_t rc;
 430   char *p;
 431
 432   if (!pwm)
 433     return GPG_ERR_INV_ARG;
 434
 435   p = pwm->filename;
 436   if (which == PWMD_PINENTRY_CLOSE)
 437     {
 438       _pinentry_disconnect (pwm);
 439       return 0;
 440     }
 441
 442   if (!result && which != PWMD_PINENTRY_CONFIRM)
 443     return GPG_ERR_INV_ARG;
 444
 445   /* Another handle is using this pinentry method. Allowing this instance
 446    * would reset the timeout and global handle which wouldn't be good. */
 447   if (gpwm)
 448     return GPG_ERR_PIN_BLOCKED;
 449
 450   if (pwm->pinentry_timeout != 0)
 451     {
 452       gpwm = pwm;
 453       gtimeout = abs (pwm->pinentry_timeout);
 454       gelapsed = 0;
 455     }
 456
 457   pwm->filename = (char *) filename;
 458   rc = _getpin (pwm, result, len, which);
 459   pwm->filename = p;
 460
 461   /* Don't timeout when an invalid passphrase was entered. */
 462   gtimeout = 0;
 463   gpwm = NULL;
 464   return rc;
 465 }