lib/krb5/fcache.c

   1 /*
   2  * Copyright (c) 1997 - 2004 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "krb5_locl.h"
  35
  36 RCSID("$Id$");
  37
  38 typedef struct krb5_fcache{
  39     char *filename;
  40     int version;
  41 }krb5_fcache;
  42
  43 struct fcc_cursor {
  44     int fd;
  45     krb5_storage *sp;
  46 };
  47
  48 #define KRB5_FCC_FVNO_1 1
  49 #define KRB5_FCC_FVNO_2 2
  50 #define KRB5_FCC_FVNO_3 3
  51 #define KRB5_FCC_FVNO_4 4
  52
  53 #define FCC_TAG_DELTATIME 1
  54
  55 #define FCACHE(X) ((krb5_fcache*)(X)->data.data)
  56
  57 #define FILENAME(X) (FCACHE(X)->filename)
  58
  59 #define FCC_CURSOR(C) ((struct fcc_cursor*)(C))
  60
  61 static const char*
  62 fcc_get_name(krb5_context context,
  63              krb5_ccache id)
  64 {
  65     return FILENAME(id);
  66 }
  67
  68 int
  69 _krb5_xlock(krb5_context context, int fd, krb5_boolean exclusive,
  70             const char *filename)
  71 {
  72     int ret;
  73 #ifdef HAVE_FCNTL
  74     struct flock l;
  75
  76     l.l_start = 0;
  77     l.l_len = 0;
  78     l.l_type = exclusive ? F_WRLCK : F_RDLCK;
  79     l.l_whence = SEEK_SET;
  80     ret = fcntl(fd, F_SETLKW, &l);
  81 #else
  82     ret = flock(fd, exclusive ? LOCK_EX : LOCK_SH);
  83 #endif
  84     if(ret < 0)
  85         ret = errno;
  86     if(ret == EACCES) /* fcntl can return EACCES instead of EAGAIN */
  87         ret = EAGAIN;
  88
  89     switch (ret) {
  90     case 0:
  91         break;
  92     case EINVAL: /* filesystem doesn't support locking, let the user have it */
  93         ret = 0;
  94         break;
  95     case EAGAIN:
  96         krb5_set_error_string(context, "timed out locking cache file %s",
  97                               filename);
  98         break;
  99     default:
 100         krb5_set_error_string(context, "error locking cache file %s: %s",
 101                               filename, strerror(ret));
 102         break;
 103     }
 104     return ret;
 105 }
 106
 107 int
 108 _krb5_xunlock(int fd)
 109 {
 110 #ifdef HAVE_FCNTL_LOCK
 111     struct flock l;
 112     l.l_start = 0;
 113     l.l_len = 0;
 114     l.l_type = F_UNLCK;
 115     l.l_whence = SEEK_SET;
 116     return fcntl(fd, F_SETLKW, &l);
 117 #else
 118     return flock(fd, LOCK_UN);
 119 #endif
 120 }
 121
 122 static krb5_error_code
 123 fcc_lock(krb5_context context, krb5_ccache id,
 124          int fd, krb5_boolean exclusive)
 125 {
 126     return _krb5_xlock(context, fd, exclusive, fcc_get_name(context, id));
 127 }
 128
 129 static krb5_error_code
 130 fcc_unlock(krb5_context context, int fd)
 131 {
 132     return _krb5_xunlock(fd);
 133 }
 134
 135 static krb5_error_code
 136 fcc_resolve(krb5_context context, krb5_ccache *id, const char *res)
 137 {
 138     krb5_fcache *f;
 139     f = malloc(sizeof(*f));
 140     if(f == NULL) {
 141         krb5_set_error_string(context, "malloc: out of memory");
 142         return KRB5_CC_NOMEM;
 143     }
 144     f->filename = strdup(res);
 145     if(f->filename == NULL){
 146         free(f);
 147         krb5_set_error_string(context, "malloc: out of memory");
 148         return KRB5_CC_NOMEM;
 149     }
 150     f->version = 0;
 151     (*id)->data.data = f;
 152     (*id)->data.length = sizeof(*f);
 153     return 0;
 154 }
 155
 156 /*
 157  * Try to scrub the contents of `filename' safely.
 158  */
 159
 160 static int
 161 scrub_file (int fd)
 162 {
 163     off_t pos;
 164     char buf[128];
 165
 166     pos = lseek(fd, 0, SEEK_END);
 167     if (pos < 0)
 168         return errno;
 169     if (lseek(fd, 0, SEEK_SET) < 0)
 170         return errno;
 171     memset(buf, 0, sizeof(buf));
 172     while(pos > 0) {
 173         ssize_t tmp = write(fd, buf, min(sizeof(buf), pos));
 174
 175         if (tmp < 0)
 176             return errno;
 177         pos -= tmp;
 178     }
 179     fsync (fd);
 180     return 0;
 181 }
 182
 183 /*
 184  * Erase `filename' if it exists, trying to remove the contents if
 185  * it's `safe'.  We always try to remove the file, it it exists.  It's
 186  * only overwritten if it's a regular file (not a symlink and not a
 187  * hardlink)
 188  */
 189
 190 static krb5_error_code
 191 erase_file(const char *filename)
 192 {
 193     int fd;
 194     struct stat sb1, sb2;
 195     int ret;
 196
 197     ret = lstat (filename, &sb1);
 198     if (ret < 0)
 199         return errno;
 200
 201     fd = open(filename, O_RDWR | O_BINARY);
 202     if(fd < 0) {
 203         if(errno == ENOENT)
 204             return 0;
 205         else
 206             return errno;
 207     }
 208     if (unlink(filename) < 0) {
 209         close (fd);
 210         return errno;
 211     }
 212     ret = fstat (fd, &sb2);
 213     if (ret < 0) {
 214         close (fd);
 215         return errno;
 216     }
 217
 218     /* check if someone was playing with symlinks */
 219
 220     if (sb1.st_dev != sb2.st_dev || sb1.st_ino != sb2.st_ino) {
 221         close (fd);
 222         return EPERM;
 223     }
 224
 225     /* there are still hard links to this file */
 226
 227     if (sb2.st_nlink != 0) {
 228         close (fd);
 229         return 0;
 230     }
 231
 232     ret = scrub_file (fd);
 233     close (fd);
 234     return ret;
 235 }
 236
 237 static krb5_error_code
 238 fcc_gen_new(krb5_context context, krb5_ccache *id)
 239 {
 240     krb5_fcache *f;
 241     int fd;
 242     char *file;
 243
 244     f = malloc(sizeof(*f));
 245     if(f == NULL) {
 246         krb5_set_error_string(context, "malloc: out of memory");
 247         return KRB5_CC_NOMEM;
 248     }
 249     asprintf (&file, "%sXXXXXX", KRB5_DEFAULT_CCFILE_ROOT);
 250     if(file == NULL) {
 251         free(f);
 252         krb5_set_error_string(context, "malloc: out of memory");
 253         return KRB5_CC_NOMEM;
 254     }
 255     fd = mkstemp(file);
 256     if(fd < 0) {
 257         free(f);
 258         free(file);
 259         krb5_set_error_string(context, "mkstemp %s", file);
 260         return errno;
 261     }
 262     close(fd);
 263     f->filename = file;
 264     f->version = 0;
 265     (*id)->data.data = f;
 266     (*id)->data.length = sizeof(*f);
 267     return 0;
 268 }
 269
 270 static void
 271 storage_set_flags(krb5_context context, krb5_storage *sp, int vno)
 272 {
 273     int flags = 0;
 274     switch(vno) {
 275     case KRB5_FCC_FVNO_1:
 276         flags |= KRB5_STORAGE_PRINCIPAL_WRONG_NUM_COMPONENTS;
 277         flags |= KRB5_STORAGE_PRINCIPAL_NO_NAME_TYPE;
 278         flags |= KRB5_STORAGE_HOST_BYTEORDER;
 279         break;
 280     case KRB5_FCC_FVNO_2:
 281         flags |= KRB5_STORAGE_HOST_BYTEORDER;
 282         break;
 283     case KRB5_FCC_FVNO_3:
 284         flags |= KRB5_STORAGE_KEYBLOCK_KEYTYPE_TWICE;
 285         break;
 286     case KRB5_FCC_FVNO_4:
 287         break;
 288     default:
 289         krb5_abortx(context,
 290                     "storage_set_flags called with bad vno (%x)", vno);
 291     }
 292     krb5_storage_set_flags(sp, flags);
 293 }
 294
 295 static krb5_error_code
 296 fcc_open(krb5_context context,
 297          krb5_ccache id,
 298          int *fd_ret,
 299          int flags,
 300          mode_t mode)
 301 {
 302     krb5_boolean exclusive = ((flags | O_WRONLY) == flags ||
 303                               (flags | O_RDWR) == flags);
 304     krb5_error_code ret;
 305     const char *filename = FILENAME(id);
 306     int fd;
 307     fd = open(filename, flags, mode);
 308     if(fd < 0) {
 309         ret = errno;
 310         krb5_set_error_string(context, "open(%s): %s", filename,
 311                               strerror(ret));
 312         return ret;
 313     }
 314
 315     if((ret = fcc_lock(context, id, fd, exclusive)) != 0) {
 316         close(fd);
 317         return ret;
 318     }
 319     *fd_ret = fd;
 320     return 0;
 321 }
 322
 323 static krb5_error_code
 324 fcc_initialize(krb5_context context,
 325                krb5_ccache id,
 326                krb5_principal primary_principal)
 327 {
 328     krb5_fcache *f = FCACHE(id);
 329     int ret = 0;
 330     int fd;
 331     char *filename = f->filename;
 332
 333     unlink (filename);
 334
 335     ret = fcc_open(context, id, &fd, O_RDWR | O_CREAT | O_EXCL | O_BINARY, 0600);
 336     if(ret)
 337         return ret;
 338     {
 339         krb5_storage *sp;
 340         sp = krb5_storage_from_fd(fd);
 341         krb5_storage_set_eof_code(sp, KRB5_CC_END);
 342         if(context->fcache_vno != 0)
 343             f->version = context->fcache_vno;
 344         else
 345             f->version = KRB5_FCC_FVNO_4;
 346         ret |= krb5_store_int8(sp, 5);
 347         ret |= krb5_store_int8(sp, f->version);
 348         storage_set_flags(context, sp, f->version);
 349         if(f->version == KRB5_FCC_FVNO_4 && ret == 0) {
 350             /* V4 stuff */
 351             if (context->kdc_sec_offset) {
 352                 ret |= krb5_store_int16 (sp, 12); /* length */
 353                 ret |= krb5_store_int16 (sp, FCC_TAG_DELTATIME); /* Tag */
 354                 ret |= krb5_store_int16 (sp, 8); /* length of data */
 355                 ret |= krb5_store_int32 (sp, context->kdc_sec_offset);
 356                 ret |= krb5_store_int32 (sp, context->kdc_usec_offset);
 357             } else {
 358                 ret |= krb5_store_int16 (sp, 0);
 359             }
 360         }
 361         ret |= krb5_store_principal(sp, primary_principal);
 362
 363         krb5_storage_free(sp);
 364     }
 365     fcc_unlock(context, fd);
 366     if (close(fd) < 0)
 367         if (ret == 0) {
 368             ret = errno;
 369             krb5_set_error_string (context, "close %s: %s",
 370                                    FILENAME(id), strerror(ret));
 371         }
 372     return ret;
 373 }
 374
 375 static krb5_error_code
 376 fcc_close(krb5_context context,
 377           krb5_ccache id)
 378 {
 379     free (FILENAME(id));
 380     krb5_data_free(&id->data);
 381     return 0;
 382 }
 383
 384 static krb5_error_code
 385 fcc_destroy(krb5_context context,
 386             krb5_ccache id)
 387 {
 388     erase_file(FILENAME(id));
 389     return 0;
 390 }
 391
 392 static krb5_error_code
 393 fcc_store_cred(krb5_context context,
 394                krb5_ccache id,
 395                krb5_creds *creds)
 396 {
 397     int ret;
 398     int fd;
 399
 400     ret = fcc_open(context, id, &fd, O_WRONLY | O_APPEND | O_BINARY, 0);
 401     if(ret)
 402         return ret;
 403     {
 404         krb5_storage *sp;
 405         sp = krb5_storage_from_fd(fd);
 406         krb5_storage_set_eof_code(sp, KRB5_CC_END);
 407         storage_set_flags(context, sp, FCACHE(id)->version);
 408         if (krb5_config_get_bool_default(context, NULL, FALSE,
 409                                          "libdefaults",
 410                                          "fcc-mit-ticketflags",
 411                                          NULL))
 412             ret = _krb5_store_creds_heimdal_0_7(sp, creds);
 413         else
 414             ret = _krb5_store_creds_heimdal_pre_0_7(sp, creds);
 415         krb5_storage_free(sp);
 416     }
 417     fcc_unlock(context, fd);
 418     if (close(fd) < 0)
 419         if (ret == 0) {
 420             ret = errno;
 421             krb5_set_error_string (context, "close %s: %s",
 422                                    FILENAME(id), strerror(ret));
 423         }
 424     return ret;
 425 }
 426
 427 static krb5_error_code
 428 init_fcc (krb5_context context,
 429           krb5_ccache id,
 430           krb5_storage **ret_sp,
 431           int *ret_fd)
 432 {
 433     int fd;
 434     int8_t pvno, tag;
 435     krb5_storage *sp;
 436     krb5_error_code ret;
 437
 438     ret = fcc_open(context, id, &fd, O_RDONLY | O_BINARY, 0);
 439
 440     if(ret)
 441         return ret;
 442
 443     sp = krb5_storage_from_fd(fd);
 444     if(sp == NULL) {
 445         ret = ENOMEM;
 446         goto out;
 447     }
 448     krb5_storage_set_eof_code(sp, KRB5_CC_END);
 449     ret = krb5_ret_int8(sp, &pvno);
 450     if(ret != 0) {
 451         if(ret == KRB5_CC_END)
 452             ret = ENOENT; /* empty file */
 453         goto out;
 454     }
 455     if(pvno != 5) {
 456         ret = KRB5_CCACHE_BADVNO;
 457         goto out;
 458     }
 459     ret = krb5_ret_int8(sp, &tag); /* should not be host byte order */
 460     if(ret != 0) {
 461         ret = KRB5_CC_FORMAT;
 462         goto out;
 463     }
 464     FCACHE(id)->version = tag;
 465     storage_set_flags(context, sp, FCACHE(id)->version);
 466     switch (tag) {
 467     case KRB5_FCC_FVNO_4: {
 468         int16_t length;
 469
 470         ret = krb5_ret_int16 (sp, &length);
 471         if(ret) {
 472             ret = KRB5_CC_FORMAT;
 473             goto out;
 474         }
 475         while(length > 0) {
 476             int16_t tag, data_len;
 477             int i;
 478             int8_t dummy;
 479
 480             ret = krb5_ret_int16 (sp, &tag);
 481             if(ret) {
 482                 ret = KRB5_CC_FORMAT;
 483                 goto out;
 484             }
 485             ret = krb5_ret_int16 (sp, &data_len);
 486             if(ret) {
 487                 ret = KRB5_CC_FORMAT;
 488                 goto out;
 489             }
 490             switch (tag) {
 491             case FCC_TAG_DELTATIME :
 492                 ret = krb5_ret_int32 (sp, &context->kdc_sec_offset);
 493                 if(ret) {
 494                     ret = KRB5_CC_FORMAT;
 495                     goto out;
 496                 }
 497                 ret = krb5_ret_int32 (sp, &context->kdc_usec_offset);
 498                 if(ret) {
 499                     ret = KRB5_CC_FORMAT;
 500                     goto out;
 501                 }
 502                 break;
 503             default :
 504                 for (i = 0; i < data_len; ++i) {
 505                     ret = krb5_ret_int8 (sp, &dummy);
 506                     if(ret) {
 507                         ret = KRB5_CC_FORMAT;
 508                         goto out;
 509                     }
 510                 }
 511                 break;
 512             }
 513             length -= 4 + data_len;
 514         }
 515         break;
 516     }
 517     case KRB5_FCC_FVNO_3:
 518     case KRB5_FCC_FVNO_2:
 519     case KRB5_FCC_FVNO_1:
 520         break;
 521     default :
 522         ret = KRB5_CCACHE_BADVNO;
 523         goto out;
 524     }
 525     *ret_sp = sp;
 526     *ret_fd = fd;
 527
 528     return 0;
 529   out:
 530     if(sp != NULL)
 531         krb5_storage_free(sp);
 532     fcc_unlock(context, fd);
 533     close(fd);
 534     return ret;
 535 }
 536
 537 static krb5_error_code
 538 fcc_get_principal(krb5_context context,
 539                   krb5_ccache id,
 540                   krb5_principal *principal)
 541 {
 542     krb5_error_code ret;
 543     int fd;
 544     krb5_storage *sp;
 545
 546     ret = init_fcc (context, id, &sp, &fd);
 547     if (ret)
 548         return ret;
 549     ret = krb5_ret_principal(sp, principal);
 550     krb5_storage_free(sp);
 551     fcc_unlock(context, fd);
 552     close(fd);
 553     return ret;
 554 }
 555
 556 static krb5_error_code
 557 fcc_end_get (krb5_context context,
 558              krb5_ccache id,
 559              krb5_cc_cursor *cursor);
 560
 561 static krb5_error_code
 562 fcc_get_first (krb5_context context,
 563                krb5_ccache id,
 564                krb5_cc_cursor *cursor)
 565 {
 566     krb5_error_code ret;
 567     krb5_principal principal;
 568
 569     *cursor = malloc(sizeof(struct fcc_cursor));
 570
 571     ret = init_fcc (context, id, &FCC_CURSOR(*cursor)->sp,
 572                     &FCC_CURSOR(*cursor)->fd);
 573     if (ret) {
 574         free(*cursor);
 575         return ret;
 576     }
 577     ret = krb5_ret_principal (FCC_CURSOR(*cursor)->sp, &principal);
 578     if(ret) {
 579         fcc_end_get(context, id, cursor);
 580         return ret;
 581     }
 582     krb5_free_principal (context, principal);
 583     fcc_unlock(context, FCC_CURSOR(*cursor)->fd);
 584     return 0;
 585 }
 586
 587 static krb5_error_code
 588 fcc_get_next (krb5_context context,
 589               krb5_ccache id,
 590               krb5_cc_cursor *cursor,
 591               krb5_creds *creds)
 592 {
 593     krb5_error_code ret;
 594     if((ret = fcc_lock(context, id, FCC_CURSOR(*cursor)->fd, FALSE)) != 0)
 595         return ret;
 596
 597     ret = krb5_ret_creds(FCC_CURSOR(*cursor)->sp, creds);
 598
 599     fcc_unlock(context, FCC_CURSOR(*cursor)->fd);
 600     return ret;
 601 }
 602
 603 static krb5_error_code
 604 fcc_end_get (krb5_context context,
 605              krb5_ccache id,
 606              krb5_cc_cursor *cursor)
 607 {
 608     krb5_storage_free(FCC_CURSOR(*cursor)->sp);
 609     close (FCC_CURSOR(*cursor)->fd);
 610     free(*cursor);
 611     *cursor = NULL;
 612     return 0;
 613 }
 614
 615 static krb5_error_code
 616 fcc_remove_cred(krb5_context context,
 617                  krb5_ccache id,
 618                  krb5_flags which,
 619                  krb5_creds *cred)
 620 {
 621     return 0; /* XXX */
 622 }
 623
 624 static krb5_error_code
 625 fcc_set_flags(krb5_context context,
 626               krb5_ccache id,
 627               krb5_flags flags)
 628 {
 629     return 0; /* XXX */
 630 }
 631
 632 static krb5_error_code
 633 fcc_get_version(krb5_context context,
 634                 krb5_ccache id)
 635 {
 636     return FCACHE(id)->version;
 637 }
 638
 639 const krb5_cc_ops krb5_fcc_ops = {
 640     "FILE",
 641     fcc_get_name,
 642     fcc_resolve,
 643     fcc_gen_new,
 644     fcc_initialize,
 645     fcc_destroy,
 646     fcc_close,
 647     fcc_store_cred,
 648     NULL, /* fcc_retrieve */
 649     fcc_get_principal,
 650     fcc_get_first,
 651     fcc_get_next,
 652     fcc_end_get,
 653     fcc_remove_cred,
 654     fcc_set_flags,
 655     fcc_get_version
 656 };