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 #define _FILE_OFFSET_BITS 64
  32
  33 #include "config.h"
  34
  35 #include <errno.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <time.h>
  40
  41 #include <mLib/base64.h>
  42 #include <mLib/bits.h>
  43 #include <mLib/dstr.h>
  44 #include <mLib/mdwopt.h>
  45 #include <mLib/quis.h>
  46 #include <mLib/report.h>
  47 #include <mLib/sub.h>
  48
  49 #include "cc.h"
  50 #include "key.h"
  51 #include "gmac.h"
  52 #include "getdate.h"
  53
  54 /*----- Handy global state ------------------------------------------------*/
  55
  56 static const char *keyfile = "keyring";
  57
  58 /*----- Cookie format -----------------------------------------------------*/
  59
  60 /* --- Cookie header structure (unpacked) --- */
  61
  62 typedef struct cookie {
  63   uint32 k;
  64   time_t exp;
  65 } cookie;
  66
  67 /* --- Size of a cookie header (packed) --- */
  68
  69 #define COOKIE_SZ (4 + 8)
  70
  71 /* --- @COOKIE_PACK@ --- *
  72  *
  73  * Arguments:   @p@ = pointer to destination buffer
  74  *              @c@ = pointer to source cookie header block
  75  *
  76  * Use:         Packs a cookie header into an octet buffer in a machine-
  77  *              independent way.
  78  */
  79
  80 #define COOKIE_PACK(p, c) do {                                          \
  81   octet *_p = (octet *)(p);                                             \
  82   const cookie *_c = (c);                                               \
  83   STORE32(_p + 0, _c->k);                                               \
  84   STORE32(_p + 4, ((_c->exp & ~MASK32) >> 16) >> 16);                   \
  85   STORE32(_p + 8, _c->exp);                                             \
  86 } while (0)
  87
  88 /* --- @COOKIE_UNPACK@ --- *
  89  *
  90  * Arguments:   @c@ = pointer to destination cookie header
  91  *              @p@ = pointer to source buffer
  92  *
  93  * Use:         Unpacks a cookie header from an octet buffer into a
  94  *              machine-specific but comprehensible structure.
  95  */
  96
  97 #define COOKIE_UNPACK(c, p) do {                                        \
  98   cookie *_c = (c);                                                     \
  99   const octet *_p = (const octet *)(p);                                 \
 100   _c->k = LOAD32(_p + 0);                                               \
 101   _c->exp = ((time_t)(((LOAD32(_p + 4) << 16) << 16) & ~MASK32) |       \
 102              (time_t)LOAD32(_p + 8));                                   \
 103 } while (0)
 104
 105 /*----- Useful shared functions -------------------------------------------*/
 106
 107 /* --- @doopen@ --- *
 108  *
 109  * Arguments:   @key_file *f@ = pointer to key file block
 110  *              @unsigned how@ = method to open file with
 111  *
 112  * Returns:     ---
 113  *
 114  * Use:         Opens a key file and handles errors by panicking
 115  *              appropriately.
 116  */
 117
 118 static void doopen(key_file *f, unsigned how)
 119 {
 120   if (key_open(f, keyfile, how, key_moan, 0)) {
 121     die(EXIT_FAILURE, "couldn't open file `%s': %s",
 122         keyfile, strerror(errno));
 123   }
 124 }
 125
 126 /* --- @doclose@ --- *
 127  *
 128  * Arguments:   @key_file *f@ = pointer to key file block
 129  *
 130  * Returns:     ---
 131  *
 132  * Use:         Closes a key file and handles errors by panicking
 133  *              appropriately.
 134  */
 135
 136 static void doclose(key_file *f)
 137 {
 138   switch (key_close(f)) {
 139     case KWRITE_FAIL:
 140       die(EXIT_FAILURE, "couldn't write file `%s': %s",
 141           keyfile, strerror(errno));
 142     case KWRITE_BROKEN:
 143       die(EXIT_FAILURE, "keyring file `%s' broken: %s (repair manually)",
 144           keyfile, strerror(errno));
 145   }
 146 }
 147
 148 /* --- @getmac@ --- *
 149  *
 150  * Arguments:   @key *k@ = key to use
 151  *              @const char *app@ = application name
 152  *
 153  * Returns:     The MAC to use.
 154  *
 155  * Use:         Finds the right MAC for the given key.
 156  */
 157
 158 static gmac *getmac(key *k, const char *app)
 159 {
 160   dstr t = DSTR_INIT;
 161   dstr d = DSTR_INIT;
 162   char *p = 0;
 163   const char *q;
 164   size_t n;
 165   key_bin kb;
 166   key_packdef kp;
 167   const gcmac *cm;
 168   int e;
 169   gmac *m;
 170
 171   /* --- Set up --- */
 172
 173   key_fulltag(k, &t);
 174
 175   /* --- Pick out the right MAC --- */
 176
 177   n = strlen(app);
 178   if ((q = key_getattr(0, k, "mac")) != 0) {
 179     dstr_puts(&d, q);
 180     p = d.buf;
 181   } else if (strncmp(k->type, app, n) == 0 && k->type[n] == '-') {
 182     dstr_puts(&d, k->type);
 183     p = d.buf + n + 1;
 184   } else
 185     die(EXIT_FAILURE, "no MAC algorithm for key `%s'", t.buf);
 186   if ((cm = gmac_byname(p)) == 0) {
 187     die(EXIT_FAILURE, "MAC algorithm `%s' not found in key `%s'",
 188         p, t.buf);
 189   }
 190
 191   /* --- Unlock the key --- */
 192
 193   kp.e = KENC_BINARY;
 194   kp.p = &kb;
 195   if ((e = key_unpack(&kp, k->k, &t)) != 0) {
 196     die(EXIT_FAILURE, "error unpacking key `%s': %s",
 197         t.buf, key_strerror(e));
 198   }
 199
 200   /* --- Make the MAC object --- */
 201
 202   if (keysz(kb.sz, cm->keysz) != kb.sz)
 203     die(EXIT_FAILURE, "key %s has bad length (%lu) for MAC %s",
 204         t.buf, (unsigned long)kb.sz, cm->name);
 205   m = cm->key(kb.k, kb.sz);
 206   key_unpackdone(&kp);
 207   return (m);
 208 }
 209
 210 /*----- Command implementation --------------------------------------------*/
 211
 212 /* --- @cmd_gen@ --- */
 213
 214 static int cmd_gen(int argc, char *argv[])
 215 {
 216   key_file f;
 217   key *k;
 218   gmac *m;
 219   ghash *h;
 220   const char *tag = "cookie";
 221   int err;
 222   cookie c = { 0, KEXP_EXPIRE };
 223   unsigned fl = 0;
 224   int bits = 32;
 225   const octet *t;
 226   dstr d = DSTR_INIT;
 227   octet buf[COOKIE_SZ];
 228   base64_ctx b;
 229
 230   /* --- Various useful flag bits --- */
 231
 232 #define f_bogus 1u
 233
 234   /* --- Parse options for the subcommand --- */
 235
 236   for (;;) {
 237     static struct option opt[] = {
 238       { "bits",         OPTF_ARGREQ,    0,      'b' },
 239       { "expire",       OPTF_ARGREQ,    0,      'e' },
 240       { "key",          OPTF_ARGREQ,    0,      'k' },
 241       { 0,              0,              0,      0 }
 242     };
 243     int i = mdwopt(argc, argv, "+b:e:i:t:", opt, 0, 0, 0);
 244     if (i < 0)
 245       break;
 246
 247     /* --- Handle the various options --- */
 248
 249     switch (i) {
 250
 251       /* --- Fetch a size in bits --- */
 252
 253       case 'b':
 254         if (!(bits = atoi(optarg)) || bits % 8)
 255           die(EXIT_FAILURE, "bad number of bits: `%s'", optarg);
 256         break;
 257
 258       /* --- Fetch an expiry time --- */
 259
 260       case 'e':
 261         if (strcmp(optarg, "forever") == 0)
 262           c.exp = KEXP_FOREVER;
 263         else if ((c.exp = get_date(optarg, 0)) == -1)
 264           die(EXIT_FAILURE, "bad expiry date: `%s'", optarg);
 265         break;
 266
 267       /* --- Fetch a key type --- */
 268
 269       case 'k':
 270         tag = optarg;
 271         break;
 272
 273       /* --- Other things are bogus --- */
 274
 275       default:
 276         fl |= f_bogus;
 277         break;
 278     }
 279   }
 280
 281   /* --- Various sorts of bogosity --- */
 282
 283   if (fl & f_bogus || optind + 1 < argc)
 284     die(EXIT_FAILURE,
 285         "Usage: generate [-b BITS] [-e TIME] [-k TAG] [DATA]");
 286
 287   /* --- Choose a default expiry time --- */
 288
 289   if (c.exp == KEXP_EXPIRE)
 290     c.exp = time(0) + 7 * 24 * 60 * 60;
 291
 292   /* --- Open the key file and get the key --- */
 293
 294   doopen(&f, KOPEN_WRITE);
 295   if ((k = key_bytag(&f, tag)) == 0) {
 296     die(EXIT_FAILURE, "no key with tag `%s' in keyring `%s'",
 297         tag, keyfile);
 298   }
 299
 300   c.k = k->id;
 301   if ((err = key_used(&f, k, c.exp)) != 0)
 302     die(EXIT_FAILURE, "can't generate cookie: %s", key_strerror(err));
 303   m = getmac(k, "cookie");
 304   if (bits/8 > GM_CLASS(m)->hashsz) {
 305     die(EXIT_FAILURE, "inapproriate bit length for `%s' MACs",
 306         GM_CLASS(m)->name);
 307   }
 308
 309   /* --- Store and MAC the cookie --- */
 310
 311   COOKIE_PACK(buf, &c);
 312
 313   h = GM_INIT(m);
 314   GH_HASH(h, buf, sizeof(buf));
 315   if (argv[optind])
 316     GH_HASH(h, argv[optind], strlen(argv[optind]));
 317   t = GH_DONE(h, 0);
 318
 319   /* --- Encode and emit the finished cookie --- */
 320
 321   base64_init(&b);
 322   b.indent = "";
 323   base64_encode(&b, buf, sizeof(buf), &d);
 324   base64_encode(&b, t, bits/8, &d);
 325   base64_encode(&b, 0, 0, &d);
 326   DWRITE(&d, stdout);
 327   fputc('\n', stdout);
 328   DDESTROY(&d);
 329   GH_DESTROY(h);
 330   GM_DESTROY(m);
 331
 332   doclose(&f);
 333   return (0);
 334
 335 #undef f_bogus
 336 }
 337
 338 /* --- @cmd_verify@ --- */
 339
 340 static int cmd_verify(int argc, char *argv[])
 341 {
 342   key_file f;
 343   dstr d = DSTR_INIT;
 344   unsigned fl = 0;
 345   int bits = -1, minbits = 32;
 346   int v = 1;
 347   base64_ctx b;
 348   gmac *m;
 349   ghash *h;
 350   cookie c;
 351   key *k;
 352   int cbits;
 353   const octet *t;
 354   time_t now = time(0);
 355
 356   /* --- Various useful flag bits --- */
 357
 358 #define f_bogus 1u
 359 #define f_forever 2u
 360 #define f_utc 4u
 361
 362   /* --- Parse options for the subcommand --- */
 363
 364   for (;;) {
 365     static struct option opt[] = {
 366       { "bits",         OPTF_ARGREQ,    0,      'b' },
 367       { "min-bits",     OPTF_ARGREQ,    0,      'm' },
 368       { "forever",      0,              0,      'f' },
 369       { "quiet",        0,              0,      'q' },
 370       { "verbose",      0,              0,      'v' },
 371       { "utc",          0,              0,      'u' },
 372       { 0,              0,              0,      0 }
 373     };
 374     int i = mdwopt(argc, argv, "+b:m:fqvu", opt, 0, 0, 0);
 375     if (i < 0)
 376       break;
 377
 378     /* --- Handle the various options --- */
 379
 380     switch (i) {
 381
 382       /* --- Fetch a size in bits --- */
 383
 384       case 'b':
 385         if (!(bits = atoi(optarg)) || bits % 8)
 386           die(EXIT_FAILURE, "bad number of bits: `%s'", optarg);
 387         break;
 388       case 'm':
 389         if (!(minbits = atoi(optarg)) || minbits % 8)
 390           die(EXIT_FAILURE, "bad number of bits: `%s'", optarg);
 391         break;
 392
 393       /* --- Miscellaneous flags --- */
 394
 395       case 'f':
 396         fl |= f_forever;
 397         break;
 398       case 'u':
 399         fl |= f_utc;
 400         break;
 401       case 'q':
 402         if (v > 0) v--;
 403         break;
 404       case 'v':
 405         v++;
 406         break;
 407
 408       /* --- Other things are bogus --- */
 409
 410       default:
 411         fl |= f_bogus;
 412         break;
 413     }
 414   }
 415
 416   /* --- Various sorts of bogosity --- */
 417
 418   if (fl & f_bogus || optind == argc || optind + 2 < argc) {
 419     die(EXIT_FAILURE,
 420         "Usage: verify [-fuqv] [-b BITS] [-m BITS] COOKIE [DATA]");
 421   }
 422   doopen(&f, KOPEN_READ);
 423
 424   /* --- Decode the base64 wrapping --- */
 425
 426   base64_init(&b);
 427   base64_decode(&b, argv[optind], strlen(argv[optind]), &d);
 428   base64_decode(&b, 0, 0, &d);
 429
 430   if (d.len < COOKIE_SZ + 1) {
 431     if (v) printf("FAIL cookie too small\n");
 432     goto fail;
 433   }
 434
 435   /* --- Extract the relevant details --- */
 436
 437   COOKIE_UNPACK(&c, d.buf);
 438
 439   if (v > 1) {
 440     char buf[64];
 441     if (c.exp == KEXP_FOREVER)
 442       strcpy(buf, "forever");
 443     else {
 444       struct tm *tm;
 445       const char *fmt;
 446
 447       if (fl & f_utc) {
 448         tm = gmtime(&c.exp);
 449         fmt = "%Y-%m-%d %H:%M:%S UTC";
 450       } else {
 451         tm = localtime(&c.exp);
 452         fmt = "%Y-%m-%d %H:%M:%S %Z";
 453       }
 454       strftime(buf, sizeof(buf), fmt, tm);
 455     }
 456     printf("INFO keyid = %08lx; expiry = %s\n", (unsigned long)c.k, buf);
 457   }
 458
 459   /* --- Check the authentication token width --- */
 460
 461   cbits = (d.len - COOKIE_SZ) * 8;
 462   if (v > 2) printf("INFO authentication token width = %i bits\n", cbits);
 463   if (bits == -1) {
 464     if (cbits < minbits) {
 465       if (v) printf("FAIL authentication token too narrow\n");
 466       goto fail;
 467     }
 468   } else {
 469     if (cbits != bits) {
 470       if (v) printf("FAIL authentication token width doesn't match\n");
 471       goto fail;
 472     }
 473   }
 474   /* --- Get the key --- */
 475
 476   if ((k = key_byid(&f, c.k)) == 0) {
 477     if (v) printf("FAIL keyid %08lx unavailable\n", (unsigned long)c.k);
 478     goto fail;
 479   }
 480
 481   /* --- Check that the cookie authenticates OK --- */
 482
 483   m = getmac(k, "cookie");
 484   h = GM_INIT(m);
 485   GH_HASH(h, d.buf, COOKIE_SZ);
 486   if (argv[optind + 1])
 487     GH_HASH(h, argv[optind + 1], strlen(argv[optind + 1]));
 488   t = GH_DONE(h, 0);
 489
 490   if (memcmp(t, d.buf + COOKIE_SZ, cbits / 8) != 0) {
 491     if (v) printf("FAIL bad authentication token\n");
 492     goto fail;
 493   }
 494
 495   /* --- See whether the cookie has expired --- */
 496
 497   if (c.exp == KEXP_FOREVER) {
 498     if (!(fl & f_forever)) {
 499       if (v) printf("FAIL forever cookies not allowed\n");
 500       goto fail;
 501     }
 502     if (k->exp != KEXP_FOREVER) {
 503       if (v) printf("FAIL cookie lasts forever but key will expire\n");
 504       goto fail;
 505     }
 506   } else if (c.exp < now) {
 507     if (v) printf("FAIL cookie has expired\n");
 508     goto fail;
 509   }
 510
 511   if (v) printf("OK\n");
 512   key_close(&f);
 513   GM_DESTROY(m);
 514   GH_DESTROY(h);
 515   dstr_destroy(&d);
 516   return (0);
 517
 518 fail:
 519   key_close(&f);
 520   dstr_destroy(&d);
 521   return (1);
 522
 523 #undef f_bogus
 524 #undef f_forever
 525 #undef f_utc
 526 }
 527
 528 /*----- Main command table ------------------------------------------------*/
 529
 530 static int cmd_help(int, char **);
 531
 532 #define LISTS(LI)                                                       \
 533   LI("Lists", list,                                                     \
 534      listtab[i].name, listtab[i].name)                                  \
 535   LI("Message authentication algorithms", mac,                          \
 536      gmactab[i], gmactab[i]->name)
 537
 538 MAKELISTTAB(listtab, LISTS)
 539
 540 static int cmd_show(int argc, char *argv[])
 541 {
 542   return (displaylists(listtab, argv + 1));
 543 }
 544
 545 static cmd cmds[] = {
 546   { "help", cmd_help, "help [COMMAND...]" },
 547   { "show", cmd_show, "show [ITEM...]" },
 548   { "generate", cmd_gen,
 549     "generate [-b BITS] [-e TIME] [-k TAG] [DATA]", "\
 550 Options:\n\
 551 \n\
 552 -b, --bits=N            Use an N-bit token in the cookie.\n\
 553 -e, --expire=TIME       Make the cookie expire after TIME.\n\
 554 -k, --key=TAG           Use key TAG to create the token.\n\
 555 " },
 556   { "verify", cmd_verify,
 557     "verify [-fuqv] [-b BITS] [-m BITS] COOKIE [DATA]", "\
 558 Options:\n\
 559 \n\
 560 -b, --bits=N            Accept tokens exactly N bits long only.\n\
 561 -m, --min-bits=N        Accept tokens N bits long or more.\n\
 562 -f, --forever           Accept cookies which never expire.\n\
 563 -u, --utc               Output cookie expiry dates in UTC.\n\
 564 -q, --quiet             Produce less output while checking cookies.\n\
 565 -v, --verbose           Produce more output while checking cookies.\n\
 566 " },
 567   { 0, 0, 0 }
 568 };
 569
 570 static int cmd_help(int argc, char *argv[])
 571 {
 572   sc_help(cmds, stdout, argv + 1);
 573   return (0);
 574 }
 575
 576 /*----- Main code ---------------------------------------------------------*/
 577
 578 /* --- Helpful GNUy functions --- */
 579
 580 static void usage(FILE *fp)
 581 {
 582   fprintf(fp, "Usage: %s [-k KEYRING] COMMAND [ARGS]\n", QUIS);
 583 }
 584
 585 void version(FILE *fp)
 586 {
 587   fprintf(fp, "%s, Catacomb version " VERSION "\n", QUIS);
 588 }
 589
 590 void help_global(FILE *fp)
 591 {
 592   usage(fp);
 593   fputs("\n\
 594 Generates and validates cryptographic cookies.  Command line options\n\
 595 recognized are:\n\
 596 \n\
 597 -h, --help [COMMAND]    Display this help text (or help for COMMAND).\n\
 598 -v, --version           Display version number.\n\
 599 -u, --usage             Display short usage summary.\n\
 600 \n\
 601 -k, --key-file=FILE     Read and write keys in FILE.\n",
 602         fp);
 603 }
 604
 605 /* --- @main@ --- *
 606  *
 607  * Arguments:   @int argc@ = number of command line arguments
 608  *              @char *argv[]@ = array of arguments
 609  *
 610  * Returns:     Zero if OK, nonzero if not.
 611  *
 612  * Use:         Generates and validates cryptographic cookies.
 613  */
 614
 615 int main(int argc, char *argv[])
 616 {
 617   unsigned f = 0;
 618
 619 #define f_bogus 1u
 620 #define f_forever 2u
 621
 622   /* --- Initialize the library --- */
 623
 624   ego(argv[0]);
 625   sub_init();
 626
 627   /* --- Options parsing --- */
 628
 629   for (;;) {
 630     static struct option opt[] = {
 631
 632       /* --- Standard GNUy help options --- */
 633
 634       { "help",         0,              0,      'h' },
 635       { "version",      0,              0,      'v' },
 636       { "usage",        0,              0,      'u' },
 637
 638       /* --- Actual relevant options --- */
 639
 640       { "keyring",      OPTF_ARGREQ,    0,      'k' },
 641
 642       /* --- Magic terminator --- */
 643
 644       { 0,              0,              0,      0 }
 645     };
 646     int i = mdwopt(argc, argv, "+hvu k:", opt, 0, 0, 0);
 647
 648     if (i < 0)
 649       break;
 650     switch (i) {
 651
 652       /* --- Helpful GNUs --- */
 653
 654       case 'u':
 655         usage(stdout);
 656         exit(0);
 657       case 'v':
 658         version(stdout);
 659         exit(0);
 660       case 'h':
 661         sc_help(cmds, stdout, argv + optind);
 662         exit(0);
 663
 664       /* --- Real genuine useful options --- */
 665
 666       case 'k':
 667         keyfile = optarg;
 668         break;
 669
 670       /* --- Bogus things --- */
 671
 672       default:
 673         f |= f_bogus;
 674         break;
 675     }
 676   }
 677
 678   if ((f & f_bogus) || optind == argc) {
 679     usage(stderr);
 680     exit(EXIT_FAILURE);
 681   }
 682
 683   /* --- Dispatch to appropriate command handler --- */
 684
 685   argc -= optind;
 686   argv += optind;
 687   optind = 0;
 688   return (findcmd(cmds, argv[0])->cmd(argc, argv));
 689
 690 #undef f_bogus
 691 #undef f_forever
 692 }
 693
 694 /*----- That's all, folks -------------------------------------------------*/