git.distorted.org.uk Git - u/mdw/catacomb/blob - cookie.c

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Generate and validate cryptographic cookies
   6  *
   7  * (c) 1999 Mark Wooding
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with Catacomb; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Header files ------------------------------------------------------*/
  30
  31 #include "config.h"
  32
  33 #include <errno.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <time.h>
  38
  39 #include <mLib/base64.h>
  40 #include <mLib/bits.h>
  41 #include <mLib/dstr.h>
  42 #include <mLib/mdwopt.h>
  43 #include <mLib/quis.h>
  44 #include <mLib/report.h>
  45 #include <mLib/sub.h>
  46
  47 #include "cc.h"
  48 #include "key.h"
  49 #include "gmac.h"
  50 #include "getdate.h"
  51
  52 /*----- Handy global state ------------------------------------------------*/
  53
  54 static const char *keyfile = "keyring";
  55
  56 /*----- Cookie format -----------------------------------------------------*/
  57
  58 /* --- Cookie header structure (unpacked) --- */
  59
  60 typedef struct cookie {
  61   uint32 k;
  62   time_t exp;
  63 } cookie;
  64
  65 /* --- Size of a cookie header (packed) --- */
  66
  67 #define COOKIE_SZ (4 + 8)
  68
  69 /* --- @COOKIE_PACK@ --- *
  70  *
  71  * Arguments:   @p@ = pointer to destination buffer
  72  *              @c@ = pointer to source cookie header block
  73  *
  74  * Use:         Packs a cookie header into an octet buffer in a machine-
  75  *              independent way.
  76  */
  77
  78 #define COOKIE_PACK(p, c) do {                                          \
  79   octet *_p = (octet *)(p);                                             \
  80   const cookie *_c = (c);                                               \
  81   STORE32(_p + 0, _c->k);                                               \
  82   STORE32(_p + 4, ((_c->exp & ~MASK32) >> 16) >> 16);                   \
  83   STORE32(_p + 8, _c->exp);                                             \
  84 } while (0)
  85
  86 /* --- @COOKIE_UNPACK@ --- *
  87  *
  88  * Arguments:   @c@ = pointer to destination cookie header
  89  *              @p@ = pointer to source buffer
  90  *
  91  * Use:         Unpacks a cookie header from an octet buffer into a
  92  *              machine-specific but comprehensible structure.
  93  */
  94
  95 #define COOKIE_UNPACK(c, p) do {                                        \
  96   cookie *_c = (c);                                                     \
  97   const octet *_p = (const octet *)(p);                                 \
  98   _c->k = LOAD32(_p + 0);                                               \
  99   _c->exp = ((time_t)(((LOAD32(_p + 4) << 16) << 16) & ~MASK32) |       \
 100              (time_t)LOAD32(_p + 8));                                   \
 101 } while (0)
 102
 103 /*----- Useful shared functions -------------------------------------------*/
 104
 105 /* --- @doopen@ --- *
 106  *
 107  * Arguments:   @key_file *f@ = pointer to key file block
 108  *              @unsigned how@ = method to open file with
 109  *
 110  * Returns:     ---
 111  *
 112  * Use:         Opens a key file and handles errors by panicking
 113  *              appropriately.
 114  */
 115
 116 static void doopen(key_file *f, unsigned how)
 117 {
 118   if (key_open(f, keyfile, how, key_moan, 0)) {
 119     die(EXIT_FAILURE, "couldn't open file `%s': %s",
 120         keyfile, strerror(errno));
 121   }
 122 }
 123
 124 /* --- @doclose@ --- *
 125  *
 126  * Arguments:   @key_file *f@ = pointer to key file block
 127  *
 128  * Returns:     ---
 129  *
 130  * Use:         Closes a key file and handles errors by panicking
 131  *              appropriately.
 132  */
 133
 134 static void doclose(key_file *f)
 135 {
 136   switch (key_close(f)) {
 137     case KWRITE_FAIL:
 138       die(EXIT_FAILURE, "couldn't write file `%s': %s",
 139           keyfile, strerror(errno));
 140     case KWRITE_BROKEN:
 141       die(EXIT_FAILURE, "keyring file `%s' broken: %s (repair manually)",
 142           keyfile, strerror(errno));
 143   }
 144 }
 145
 146 /* --- @getmac@ --- *
 147  *
 148  * Arguments:   @key *k@ = key to use
 149  *              @const char *app@ = application name
 150  *
 151  * Returns:     The MAC to use.
 152  *
 153  * Use:         Finds the right MAC for the given key.
 154  */
 155
 156 static gmac *getmac(key *k, const char *app)
 157 {
 158   dstr t = DSTR_INIT;
 159   dstr d = DSTR_INIT;
 160   char *p = 0;
 161   const char *q;
 162   size_t n;
 163   key_bin kb;
 164   key_packdef kp;
 165   const gcmac *cm;
 166   int e;
 167   gmac *m;
 168
 169   /* --- Set up --- */
 170
 171   key_fulltag(k, &t);
 172
 173   /* --- Pick out the right MAC --- */
 174
 175   n = strlen(app);
 176   if ((q = key_getattr(0, k, "mac")) != 0) {
 177     dstr_puts(&d, q);
 178     p = d.buf;
 179   } else if (strncmp(k->type, app, n) == 0 && k->type[n] == '-') {
 180     dstr_puts(&d, k->type);
 181     p = d.buf + n + 1;
 182   } else
 183     die(EXIT_FAILURE, "no MAC algorithm for key `%s'", t.buf);
 184   if ((cm = gmac_byname(p)) == 0) {
 185     die(EXIT_FAILURE, "MAC algorithm `%s' not found in key `%s'",
 186         p, t.buf);
 187   }
 188
 189   /* --- Unlock the key --- */
 190
 191   kp.e = KENC_BINARY;
 192   kp.p = &kb;
 193   if ((e = key_unpack(&kp, k->k, &t)) != 0) {
 194     die(EXIT_FAILURE, "error unpacking key `%s': %s",
 195         t.buf, key_strerror(e));
 196   }
 197
 198   /* --- Make the MAC object --- */
 199
 200   if (keysz(kb.sz, cm->keysz) != kb.sz)
 201     die(EXIT_FAILURE, "key %s has bad length (%lu) for MAC %s",
 202         t.buf, (unsigned long)kb.sz, cm->name);
 203   m = cm->key(kb.k, kb.sz);
 204   key_unpackdone(&kp);
 205   return (m);
 206 }
 207
 208 /*----- Command implementation --------------------------------------------*/
 209
 210 /* --- @cmd_gen@ --- */
 211
 212 static int cmd_gen(int argc, char *argv[])
 213 {
 214   key_file f;
 215   key *k;
 216   gmac *m;
 217   ghash *h;
 218   const char *tag = "cookie";
 219   int err;
 220   cookie c = { 0, KEXP_EXPIRE };
 221   unsigned fl = 0;
 222   int bits = 32;
 223   const octet *t;
 224   dstr d = DSTR_INIT;
 225   octet buf[COOKIE_SZ];
 226   base64_ctx b;
 227
 228   /* --- Various useful flag bits --- */
 229
 230 #define f_bogus 1u
 231
 232   /* --- Parse options for the subcommand --- */
 233
 234   for (;;) {
 235     static struct option opt[] = {
 236       { "bits",         OPTF_ARGREQ,    0,      'b' },
 237       { "expire",       OPTF_ARGREQ,    0,      'e' },
 238       { "key",          OPTF_ARGREQ,    0,      'k' },
 239       { 0,              0,              0,      0 }
 240     };
 241     int i = mdwopt(argc, argv, "+b:e:i:t:", opt, 0, 0, 0);
 242     if (i < 0)
 243       break;
 244
 245     /* --- Handle the various options --- */
 246
 247     switch (i) {
 248
 249       /* --- Fetch a size in bits --- */
 250
 251       case 'b':
 252         if (!(bits = atoi(optarg)) || bits % 8)
 253           die(EXIT_FAILURE, "bad number of bits: `%s'", optarg);
 254         break;
 255
 256       /* --- Fetch an expiry time --- */
 257
 258       case 'e':
 259         if (strcmp(optarg, "forever") == 0)
 260           c.exp = KEXP_FOREVER;
 261         else if ((c.exp = get_date(optarg, 0)) == -1)
 262           die(EXIT_FAILURE, "bad expiry date: `%s'", optarg);
 263         break;
 264
 265       /* --- Fetch a key type --- */
 266
 267       case 'k':
 268         tag = optarg;
 269         break;
 270
 271       /* --- Other things are bogus --- */
 272
 273       default:
 274         fl |= f_bogus;
 275         break;
 276     }
 277   }
 278
 279   /* --- Various sorts of bogosity --- */
 280
 281   if (fl & f_bogus || optind + 1 < argc)
 282     die(EXIT_FAILURE,
 283         "Usage: generate [-b BITS] [-e TIME] [-k TAG] [DATA]");
 284
 285   /* --- Choose a default expiry time --- */
 286
 287   if (c.exp == KEXP_EXPIRE)
 288     c.exp = time(0) + 7 * 24 * 60 * 60;
 289
 290   /* --- Open the key file and get the key --- */
 291
 292   doopen(&f, KOPEN_WRITE);
 293   if ((k = key_bytag(&f, tag)) == 0) {
 294     die(EXIT_FAILURE, "no key with tag `%s' in keyring `%s'",
 295         tag, keyfile);
 296   }
 297
 298   c.k = k->id;
 299   if ((err = key_used(&f, k, c.exp)) != 0)
 300     die(EXIT_FAILURE, "can't generate cookie: %s", key_strerror(err));
 301   m = getmac(k, "cookie");
 302   if (bits/8 > GM_CLASS(m)->hashsz) {
 303     die(EXIT_FAILURE, "inapproriate bit length for `%s' MACs",
 304         GM_CLASS(m)->name);
 305   }
 306
 307   /* --- Store and MAC the cookie --- */
 308
 309   COOKIE_PACK(buf, &c);
 310
 311   h = GM_INIT(m);
 312   GH_HASH(h, buf, sizeof(buf));
 313   if (argv[optind])
 314     GH_HASH(h, argv[optind], strlen(argv[optind]));
 315   t = GH_DONE(h, 0);
 316
 317   /* --- Encode and emit the finished cookie --- */
 318
 319   base64_init(&b);
 320   b.indent = "";
 321   base64_encode(&b, buf, sizeof(buf), &d);
 322   base64_encode(&b, t, bits/8, &d);
 323   base64_encode(&b, 0, 0, &d);
 324   DWRITE(&d, stdout);
 325   fputc('\n', stdout);
 326   DDESTROY(&d);
 327   GH_DESTROY(h);
 328   GM_DESTROY(m);
 329
 330   doclose(&f);
 331   return (0);
 332
 333 #undef f_bogus
 334 }
 335
 336 /* --- @cmd_verify@ --- */
 337
 338 static int cmd_verify(int argc, char *argv[])
 339 {
 340   key_file f;
 341   dstr d = DSTR_INIT;
 342   unsigned fl = 0;
 343   int bits = -1, minbits = 32;
 344   int v = 1;
 345   base64_ctx b;
 346   gmac *m;
 347   ghash *h;
 348   cookie c;
 349   key *k;
 350   int cbits;
 351   const octet *t;
 352   time_t now = time(0);
 353
 354   /* --- Various useful flag bits --- */
 355
 356 #define f_bogus 1u
 357 #define f_forever 2u
 358 #define f_utc 4u
 359
 360   /* --- Parse options for the subcommand --- */
 361
 362   for (;;) {
 363     static struct option opt[] = {
 364       { "bits",         OPTF_ARGREQ,    0,      'b' },
 365       { "min-bits",     OPTF_ARGREQ,    0,      'm' },
 366       { "forever",      0,              0,      'f' },
 367       { "quiet",        0,              0,      'q' },
 368       { "verbose",      0,              0,      'v' },
 369       { "utc",          0,              0,      'u' },
 370       { 0,              0,              0,      0 }
 371     };
 372     int i = mdwopt(argc, argv, "+b:m:fqvu", opt, 0, 0, 0);
 373     if (i < 0)
 374       break;
 375
 376     /* --- Handle the various options --- */
 377
 378     switch (i) {
 379
 380       /* --- Fetch a size in bits --- */
 381
 382       case 'b':
 383         if (!(bits = atoi(optarg)) || bits % 8)
 384           die(EXIT_FAILURE, "bad number of bits: `%s'", optarg);
 385         break;
 386       case 'm':
 387         if (!(minbits = atoi(optarg)) || minbits % 8)
 388           die(EXIT_FAILURE, "bad number of bits: `%s'", optarg);
 389         break;
 390
 391       /* --- Miscellaneous flags --- */
 392
 393       case 'f':
 394         fl |= f_forever;
 395         break;
 396       case 'u':
 397         fl |= f_utc;
 398         break;
 399       case 'q':
 400         if (v > 0) v--;
 401         break;
 402       case 'v':
 403         v++;
 404         break;
 405
 406       /* --- Other things are bogus --- */
 407
 408       default:
 409         fl |= f_bogus;
 410         break;
 411     }
 412   }
 413
 414   /* --- Various sorts of bogosity --- */
 415
 416   if (fl & f_bogus || optind == argc || optind + 2 < argc) {
 417     die(EXIT_FAILURE,
 418         "Usage: verify [-fuqv] [-b BITS] [-m BITS] COOKIE [DATA]");
 419   }
 420   doopen(&f, KOPEN_READ);
 421
 422   /* --- Decode the base64 wrapping --- */
 423
 424   base64_init(&b);
 425   base64_decode(&b, argv[optind], strlen(argv[optind]), &d);
 426   base64_decode(&b, 0, 0, &d);
 427
 428   if (d.len < COOKIE_SZ + 1) {
 429     if (v) printf("FAIL cookie too small\n");
 430     goto fail;
 431   }
 432
 433   /* --- Extract the relevant details --- */
 434
 435   COOKIE_UNPACK(&c, d.buf);
 436
 437   if (v > 1) {
 438     char buf[64];
 439     if (c.exp == KEXP_FOREVER)
 440       strcpy(buf, "forever");
 441     else {
 442       struct tm *tm;
 443       const char *fmt;
 444
 445       if (fl & f_utc) {
 446         tm = gmtime(&c.exp);
 447         fmt = "%Y-%m-%d %H:%M:%S UTC";
 448       } else {
 449         tm = localtime(&c.exp);
 450         fmt = "%Y-%m-%d %H:%M:%S %Z";
 451       }
 452       strftime(buf, sizeof(buf), fmt, tm);
 453     }
 454     printf("INFO keyid = %08lx; expiry = %s\n", (unsigned long)c.k, buf);
 455   }
 456
 457   /* --- Check the authentication token width --- */
 458
 459   cbits = (d.len - COOKIE_SZ) * 8;
 460   if (v > 2) printf("INFO authentication token width = %i bits\n", cbits);
 461   if (bits == -1) {
 462     if (cbits < minbits) {
 463       if (v) printf("FAIL authentication token too narrow\n");
 464       goto fail;
 465     }
 466   } else {
 467     if (cbits != bits) {
 468       if (v) printf("FAIL authentication token width doesn't match\n");
 469       goto fail;
 470     }
 471   }
 472   /* --- Get the key --- */
 473
 474   if ((k = key_byid(&f, c.k)) == 0) {
 475     if (v) printf("FAIL keyid %08lx unavailable\n", (unsigned long)c.k);
 476     goto fail;
 477   }
 478
 479   /* --- Check that the cookie authenticates OK --- */
 480
 481   m = getmac(k, "cookie");
 482   h = GM_INIT(m);
 483   GH_HASH(h, d.buf, COOKIE_SZ);
 484   if (argv[optind + 1])
 485     GH_HASH(h, argv[optind + 1], strlen(argv[optind + 1]));
 486   t = GH_DONE(h, 0);
 487
 488   if (memcmp(t, d.buf + COOKIE_SZ, cbits / 8) != 0) {
 489     if (v) printf("FAIL bad authentication token\n");
 490     goto fail;
 491   }
 492
 493   /* --- See whether the cookie has expired --- */
 494
 495   if (c.exp == KEXP_FOREVER) {
 496     if (!(fl & f_forever)) {
 497       if (v) printf("FAIL forever cookies not allowed\n");
 498       goto fail;
 499     }
 500     if (k->exp != KEXP_FOREVER) {
 501       if (v) printf("FAIL cookie lasts forever but key will expire\n");
 502       goto fail;
 503     }
 504   } else if (c.exp < now) {
 505     if (v) printf("FAIL cookie has expired\n");
 506     goto fail;
 507   }
 508
 509   if (v) printf("OK\n");
 510   key_close(&f);
 511   GM_DESTROY(m);
 512   GH_DESTROY(h);
 513   dstr_destroy(&d);
 514   return (0);
 515
 516 fail:
 517   key_close(&f);
 518   dstr_destroy(&d);
 519   return (1);
 520
 521 #undef f_bogus
 522 #undef f_forever
 523 #undef f_utc
 524 }
 525
 526 /*----- Main command table ------------------------------------------------*/
 527
 528 static int cmd_help(int, char **);
 529
 530 #define LISTS(LI)                                                       \
 531   LI("Lists", list,                                                     \
 532      listtab[i].name, listtab[i].name)                                  \
 533   LI("Message authentication algorithms", mac,                          \
 534      gmactab[i], gmactab[i]->name)
 535
 536 MAKELISTTAB(listtab, LISTS)
 537
 538 static int cmd_show(int argc, char *argv[])
 539 {
 540   return (displaylists(listtab, argv + 1));
 541 }
 542
 543 static cmd cmds[] = {
 544   { "help", cmd_help, "help [COMMAND...]" },
 545   { "show", cmd_show, "show [ITEM...]" },
 546   { "generate", cmd_gen,
 547     "generate [-b BITS] [-e TIME] [-k TAG] [DATA]", "\
 548 Options:\n\
 549 \n\
 550 -b, --bits=N            Use an N-bit token in the cookie.\n\
 551 -e, --expire=TIME       Make the cookie expire after TIME.\n\
 552 -k, --key=TAG           Use key TAG to create the token.\n\
 553 " },
 554   { "verify", cmd_verify,
 555     "verify [-fuqv] [-b BITS] [-m BITS] COOKIE [DATA]", "\
 556 Options:\n\
 557 \n\
 558 -b, --bits=N            Accept tokens exactly N bits long only.\n\
 559 -m, --min-bits=N        Accept tokens N bits long or more.\n\
 560 -f, --forever           Accept cookies which never expire.\n\
 561 -u, --utc               Output cookie expiry dates in UTC.\n\
 562 -q, --quiet             Produce less output while checking cookies.\n\
 563 -v, --verbose           Produce more output while checking cookies.\n\
 564 " },
 565   { 0, 0, 0 }
 566 };
 567
 568 static int cmd_help(int argc, char *argv[])
 569 {
 570   sc_help(cmds, stdout, argv + 1);
 571   return (0);
 572 }
 573
 574 /*----- Main code ---------------------------------------------------------*/
 575
 576 /* --- Helpful GNUy functions --- */
 577
 578 static void usage(FILE *fp)
 579 {
 580   fprintf(fp, "Usage: %s [-k KEYRING] COMMAND [ARGS]\n", QUIS);
 581 }
 582
 583 void version(FILE *fp)
 584 {
 585   fprintf(fp, "%s, Catacomb version " VERSION "\n", QUIS);
 586 }
 587
 588 void help_global(FILE *fp)
 589 {
 590   usage(fp);
 591   fputs("\n\
 592 Generates and validates cryptographic cookies.  Command line options\n\
 593 recognized are:\n\
 594 \n\
 595 -h, --help [COMMAND]    Display this help text (or help for COMMAND).\n\
 596 -v, --version           Display version number.\n\
 597 -u, --usage             Display short usage summary.\n\
 598 \n\
 599 -k, --key-file=FILE     Read and write keys in FILE.\n",
 600         fp);
 601 }
 602
 603 /* --- @main@ --- *
 604  *
 605  * Arguments:   @int argc@ = number of command line arguments
 606  *              @char *argv[]@ = array of arguments
 607  *
 608  * Returns:     Zero if OK, nonzero if not.
 609  *
 610  * Use:         Generates and validates cryptographic cookies.
 611  */
 612
 613 int main(int argc, char *argv[])
 614 {
 615   unsigned f = 0;
 616
 617 #define f_bogus 1u
 618 #define f_forever 2u
 619
 620   /* --- Initialize the library --- */
 621
 622   ego(argv[0]);
 623   sub_init();
 624
 625   /* --- Options parsing --- */
 626
 627   for (;;) {
 628     static struct option opt[] = {
 629
 630       /* --- Standard GNUy help options --- */
 631
 632       { "help",         0,              0,      'h' },
 633       { "version",      0,              0,      'v' },
 634       { "usage",        0,              0,      'u' },
 635
 636       /* --- Actual relevant options --- */
 637
 638       { "keyring",      OPTF_ARGREQ,    0,      'k' },
 639
 640       /* --- Magic terminator --- */
 641
 642       { 0,              0,              0,      0 }
 643     };
 644     int i = mdwopt(argc, argv, "+hvu k:", opt, 0, 0, 0);
 645
 646     if (i < 0)
 647       break;
 648     switch (i) {
 649
 650       /* --- Helpful GNUs --- */
 651
 652       case 'u':
 653         usage(stdout);
 654         exit(0);
 655       case 'v':
 656         version(stdout);
 657         exit(0);
 658       case 'h':
 659         sc_help(cmds, stdout, argv + optind);
 660         exit(0);
 661
 662       /* --- Real genuine useful options --- */
 663
 664       case 'k':
 665         keyfile = optarg;
 666         break;
 667
 668       /* --- Bogus things --- */
 669
 670       default:
 671         f |= f_bogus;
 672         break;
 673     }
 674   }
 675
 676   if ((f & f_bogus) || optind == argc) {
 677     usage(stderr);
 678     exit(EXIT_FAILURE);
 679   }
 680
 681   /* --- Dispatch to appropriate command handler --- */
 682
 683   argc -= optind;
 684   argv += optind;
 685   optind = 0;
 686   return (findcmd(cmds, argv[0])->cmd(argc, argv));
 687
 688 #undef f_bogus
 689 #undef f_forever
 690 }
 691
 692 /*----- That's all, folks -------------------------------------------------*/