contrib/sendmail-8.14/libsmutil/safefile.c

   1 /*
   2  * Copyright (c) 1998-2004 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  * Copyright (c) 1983, 1995-1997 Eric P. Allman.  All rights reserved.
   5  * Copyright (c) 1988, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * By using this file, you agree to the terms and conditions set
   9  * forth in the LICENSE file which can be found at the top level of
  10  * the sendmail distribution.
  11  *
  12  */
  13
  14 #include <sendmail.h>
  15 #include <sm/io.h>
  16 #include <sm/errstring.h>
  17
  18 SM_RCSID("@(#)$Id: safefile.c,v 8.129 2008/08/04 18:07:04 gshapiro Exp $")
  19
  20
  21 /*
  22 **  SAFEFILE -- return 0 if a file exists and is safe for a user.
  23 **
  24 **      Parameters:
  25 **              fn -- filename to check.
  26 **              uid -- user id to compare against.
  27 **              gid -- group id to compare against.
  28 **              user -- user name to compare against (used for group
  29 **                      sets).
  30 **              flags -- modifiers:
  31 **                      SFF_MUSTOWN -- "uid" must own this file.
  32 **                      SFF_NOSLINK -- file cannot be a symbolic link.
  33 **              mode -- mode bits that must match.
  34 **              st -- if set, points to a stat structure that will
  35 **                      get the stat info for the file.
  36 **
  37 **      Returns:
  38 **              0 if fn exists, is owned by uid, and matches mode.
  39 **              An errno otherwise.  The actual errno is cleared.
  40 **
  41 **      Side Effects:
  42 **              none.
  43 */
  44
  45 int
  46 safefile(fn, uid, gid, user, flags, mode, st)
  47         char *fn;
  48         UID_T uid;
  49         GID_T gid;
  50         char *user;
  51         long flags;
  52         int mode;
  53         struct stat *st;
  54 {
  55         register char *p;
  56         register struct group *gr = NULL;
  57         int file_errno = 0;
  58         bool checkpath;
  59         struct stat stbuf;
  60         struct stat fstbuf;
  61         char fbuf[MAXPATHLEN];
  62
  63         if (tTd(44, 4))
  64                 sm_dprintf("safefile(%s, uid=%d, gid=%d, flags=%lx, mode=%o):\n",
  65                         fn, (int) uid, (int) gid, flags, mode);
  66         errno = 0;
  67         if (sm_strlcpy(fbuf, fn, sizeof fbuf) >= sizeof fbuf)
  68         {
  69                 if (tTd(44, 4))
  70                         sm_dprintf("\tpathname too long\n");
  71                 return ENAMETOOLONG;
  72         }
  73         fn = fbuf;
  74         if (st == NULL)
  75                 st = &fstbuf;
  76
  77         /* ignore SFF_SAFEDIRPATH if we are debugging */
  78         if (RealUid != 0 && RunAsUid == RealUid)
  79                 flags &= ~SFF_SAFEDIRPATH;
  80
  81         /* first check to see if the file exists at all */
  82 # if HASLSTAT
  83         if ((bitset(SFF_NOSLINK, flags) ? lstat(fn, st)
  84                                         : stat(fn, st)) < 0)
  85 # else /* HASLSTAT */
  86         if (stat(fn, st) < 0)
  87 # endif /* HASLSTAT */
  88         {
  89                 file_errno = errno;
  90         }
  91         else if (bitset(SFF_SETUIDOK, flags) &&
  92                  !bitset(S_IXUSR|S_IXGRP|S_IXOTH, st->st_mode) &&
  93                  S_ISREG(st->st_mode))
  94         {
  95                 /*
  96                 **  If final file is set-user-ID, run as the owner of that
  97                 **  file.  Gotta be careful not to reveal anything too
  98                 **  soon here!
  99                 */
 100
 101 # ifdef SUID_ROOT_FILES_OK
 102                 if (bitset(S_ISUID, st->st_mode))
 103 # else /* SUID_ROOT_FILES_OK */
 104                 if (bitset(S_ISUID, st->st_mode) && st->st_uid != 0 &&
 105                     st->st_uid != TrustedUid)
 106 # endif /* SUID_ROOT_FILES_OK */
 107                 {
 108                         uid = st->st_uid;
 109                         user = NULL;
 110                 }
 111 # ifdef SUID_ROOT_FILES_OK
 112                 if (bitset(S_ISGID, st->st_mode))
 113 # else /* SUID_ROOT_FILES_OK */
 114                 if (bitset(S_ISGID, st->st_mode) && st->st_gid != 0)
 115 # endif /* SUID_ROOT_FILES_OK */
 116                         gid = st->st_gid;
 117         }
 118
 119         checkpath = !bitset(SFF_NOPATHCHECK, flags) ||
 120                     (uid == 0 && !bitset(SFF_ROOTOK|SFF_OPENASROOT, flags));
 121         if (bitset(SFF_NOWLINK, flags) && !bitset(SFF_SAFEDIRPATH, flags))
 122         {
 123                 int ret;
 124
 125                 /* check the directory */
 126                 p = strrchr(fn, '/');
 127                 if (p == NULL)
 128                 {
 129                         ret = safedirpath(".", uid, gid, user,
 130                                           flags|SFF_SAFEDIRPATH, 0, 0);
 131                 }
 132                 else
 133                 {
 134                         *p = '\0';
 135                         ret = safedirpath(fn, uid, gid, user,
 136                                           flags|SFF_SAFEDIRPATH, 0, 0);
 137                         *p = '/';
 138                 }
 139                 if (ret == 0)
 140                 {
 141                         /* directory is safe */
 142                         checkpath = false;
 143                 }
 144                 else
 145                 {
 146 # if HASLSTAT
 147                         /* Need lstat() information if called stat() before */
 148                         if (!bitset(SFF_NOSLINK, flags) && lstat(fn, st) < 0)
 149                         {
 150                                 ret = errno;
 151                                 if (tTd(44, 4))
 152                                         sm_dprintf("\t%s\n", sm_errstring(ret));
 153                                 return ret;
 154                         }
 155 # endif /* HASLSTAT */
 156                         /* directory is writable: disallow links */
 157                         flags |= SFF_NOLINK;
 158                 }
 159         }
 160
 161         if (checkpath)
 162         {
 163                 int ret;
 164
 165                 p = strrchr(fn, '/');
 166                 if (p == NULL)
 167                 {
 168                         ret = safedirpath(".", uid, gid, user, flags, 0, 0);
 169                 }
 170                 else
 171                 {
 172                         *p = '\0';
 173                         ret = safedirpath(fn, uid, gid, user, flags, 0, 0);
 174                         *p = '/';
 175                 }
 176                 if (ret != 0)
 177                         return ret;
 178         }
 179
 180         /*
 181         **  If the target file doesn't exist, check the directory to
 182         **  ensure that it is writable by this user.
 183         */
 184
 185         if (file_errno != 0)
 186         {
 187                 int ret = file_errno;
 188                 char *dir = fn;
 189
 190                 if (tTd(44, 4))
 191                         sm_dprintf("\t%s\n", sm_errstring(ret));
 192
 193                 errno = 0;
 194                 if (!bitset(SFF_CREAT, flags) || file_errno != ENOENT)
 195                         return ret;
 196
 197                 /* check to see if legal to create the file */
 198                 p = strrchr(dir, '/');
 199                 if (p == NULL)
 200                         dir = ".";
 201                 else if (p == dir)
 202                         dir = "/";
 203                 else
 204                         *p = '\0';
 205                 if (stat(dir, &stbuf) >= 0)
 206                 {
 207                         int md = S_IWRITE|S_IEXEC;
 208
 209                         ret = 0;
 210                         if (stbuf.st_uid == uid)
 211                                 /* EMPTY */
 212                                 ;
 213                         else if (uid == 0 && stbuf.st_uid == TrustedUid)
 214                                 /* EMPTY */
 215                                 ;
 216                         else
 217                         {
 218                                 md >>= 3;
 219                                 if (stbuf.st_gid == gid)
 220                                         /* EMPTY */
 221                                         ;
 222 # ifndef NO_GROUP_SET
 223                                 else if (user != NULL && !DontInitGroups &&
 224                                          ((gr != NULL &&
 225                                            gr->gr_gid == stbuf.st_gid) ||
 226                                           (gr = getgrgid(stbuf.st_gid)) != NULL))
 227                                 {
 228                                         register char **gp;
 229
 230                                         for (gp = gr->gr_mem; *gp != NULL; gp++)
 231                                                 if (strcmp(*gp, user) == 0)
 232                                                         break;
 233                                         if (*gp == NULL)
 234                                                 md >>= 3;
 235                                 }
 236 # endif /* ! NO_GROUP_SET */
 237                                 else
 238                                         md >>= 3;
 239                         }
 240                         if ((stbuf.st_mode & md) != md)
 241                                 ret = errno = EACCES;
 242                 }
 243                 else
 244                         ret = errno;
 245                 if (tTd(44, 4))
 246                         sm_dprintf("\t[final dir %s uid %d mode %lo] %s\n",
 247                                 dir, (int) stbuf.st_uid,
 248                                 (unsigned long) stbuf.st_mode,
 249                                 sm_errstring(ret));
 250                 if (p != NULL)
 251                         *p = '/';
 252                 st->st_mode = ST_MODE_NOFILE;
 253                 return ret;
 254         }
 255
 256 # ifdef S_ISLNK
 257         if (bitset(SFF_NOSLINK, flags) && S_ISLNK(st->st_mode))
 258         {
 259                 if (tTd(44, 4))
 260                         sm_dprintf("\t[slink mode %lo]\tE_SM_NOSLINK\n",
 261                                 (unsigned long) st->st_mode);
 262                 return E_SM_NOSLINK;
 263         }
 264 # endif /* S_ISLNK */
 265         if (bitset(SFF_REGONLY, flags) && !S_ISREG(st->st_mode))
 266         {
 267                 if (tTd(44, 4))
 268                         sm_dprintf("\t[non-reg mode %lo]\tE_SM_REGONLY\n",
 269                                 (unsigned long) st->st_mode);
 270                 return E_SM_REGONLY;
 271         }
 272         if (bitset(SFF_NOGWFILES, flags) &&
 273             bitset(S_IWGRP, st->st_mode))
 274         {
 275                 if (tTd(44, 4))
 276                         sm_dprintf("\t[write bits %lo]\tE_SM_GWFILE\n",
 277                                 (unsigned long) st->st_mode);
 278                 return E_SM_GWFILE;
 279         }
 280         if (bitset(SFF_NOWWFILES, flags) &&
 281             bitset(S_IWOTH, st->st_mode))
 282         {
 283                 if (tTd(44, 4))
 284                         sm_dprintf("\t[write bits %lo]\tE_SM_WWFILE\n",
 285                                 (unsigned long) st->st_mode);
 286                 return E_SM_WWFILE;
 287         }
 288         if (bitset(SFF_NOGRFILES, flags) && bitset(S_IRGRP, st->st_mode))
 289         {
 290                 if (tTd(44, 4))
 291                         sm_dprintf("\t[read bits %lo]\tE_SM_GRFILE\n",
 292                                 (unsigned long) st->st_mode);
 293                 return E_SM_GRFILE;
 294         }
 295         if (bitset(SFF_NOWRFILES, flags) && bitset(S_IROTH, st->st_mode))
 296         {
 297                 if (tTd(44, 4))
 298                         sm_dprintf("\t[read bits %lo]\tE_SM_WRFILE\n",
 299                                 (unsigned long) st->st_mode);
 300                 return E_SM_WRFILE;
 301         }
 302         if (!bitset(SFF_EXECOK, flags) &&
 303             bitset(S_IWUSR|S_IWGRP|S_IWOTH, mode) &&
 304             bitset(S_IXUSR|S_IXGRP|S_IXOTH, st->st_mode))
 305         {
 306                 if (tTd(44, 4))
 307                         sm_dprintf("\t[exec bits %lo]\tE_SM_ISEXEC\n",
 308                                 (unsigned long) st->st_mode);
 309                 return E_SM_ISEXEC;
 310         }
 311         if (bitset(SFF_NOHLINK, flags) && st->st_nlink != 1)
 312         {
 313                 if (tTd(44, 4))
 314                         sm_dprintf("\t[link count %d]\tE_SM_NOHLINK\n",
 315                                 (int) st->st_nlink);
 316                 return E_SM_NOHLINK;
 317         }
 318
 319         if (uid == 0 && bitset(SFF_OPENASROOT, flags))
 320                 /* EMPTY */
 321                 ;
 322         else if (uid == 0 && !bitset(SFF_ROOTOK, flags))
 323                 mode >>= 6;
 324         else if (st->st_uid == uid)
 325                 /* EMPTY */
 326                 ;
 327         else if (uid == 0 && st->st_uid == TrustedUid)
 328                 /* EMPTY */
 329                 ;
 330         else
 331         {
 332                 mode >>= 3;
 333                 if (st->st_gid == gid)
 334                         /* EMPTY */
 335                         ;
 336 # ifndef NO_GROUP_SET
 337                 else if (user != NULL && !DontInitGroups &&
 338                          ((gr != NULL && gr->gr_gid == st->st_gid) ||
 339                           (gr = getgrgid(st->st_gid)) != NULL))
 340                 {
 341                         register char **gp;
 342
 343                         for (gp = gr->gr_mem; *gp != NULL; gp++)
 344                                 if (strcmp(*gp, user) == 0)
 345                                         break;
 346                         if (*gp == NULL)
 347                                 mode >>= 3;
 348                 }
 349 # endif /* ! NO_GROUP_SET */
 350                 else
 351                         mode >>= 3;
 352         }
 353         if (tTd(44, 4))
 354                 sm_dprintf("\t[uid %d, nlink %d, stat %lo, mode %lo] ",
 355                         (int) st->st_uid, (int) st->st_nlink,
 356                         (unsigned long) st->st_mode, (unsigned long) mode);
 357         if ((st->st_uid == uid || st->st_uid == 0 ||
 358              st->st_uid == TrustedUid ||
 359              !bitset(SFF_MUSTOWN, flags)) &&
 360             (st->st_mode & mode) == mode)
 361         {
 362                 if (tTd(44, 4))
 363                         sm_dprintf("\tOK\n");
 364                 return 0;
 365         }
 366         if (tTd(44, 4))
 367                 sm_dprintf("\tEACCES\n");
 368         return EACCES;
 369 }
 370 /*
 371 **  SAFEDIRPATH -- check to make sure a path to a directory is safe
 372 **
 373 **      Safe means not writable and owned by the right folks.
 374 **
 375 **      Parameters:
 376 **              fn -- filename to check.
 377 **              uid -- user id to compare against.
 378 **              gid -- group id to compare against.
 379 **              user -- user name to compare against (used for group
 380 **                      sets).
 381 **              flags -- modifiers:
 382 **                      SFF_ROOTOK -- ok to use root permissions to open.
 383 **                      SFF_SAFEDIRPATH -- writable directories are considered
 384 **                              to be fatal errors.
 385 **              level -- symlink recursive level.
 386 **              offset -- offset into fn to start checking from.
 387 **
 388 **      Returns:
 389 **              0 -- if the directory path is "safe".
 390 **              else -- an error number associated with the path.
 391 */
 392
 393 int
 394 safedirpath(fn, uid, gid, user, flags, level, offset)
 395         char *fn;
 396         UID_T uid;
 397         GID_T gid;
 398         char *user;
 399         long flags;
 400         int level;
 401         int offset;
 402 {
 403         int ret = 0;
 404         int mode = S_IWOTH;
 405         char save = '\0';
 406         char *saveptr = NULL;
 407         char *p, *enddir;
 408         register struct group *gr = NULL;
 409         char s[MAXLINKPATHLEN];
 410         struct stat stbuf;
 411
 412         /* make sure we aren't in a symlink loop */
 413         if (level > MAXSYMLINKS)
 414                 return ELOOP;
 415
 416         if (level < 0 || offset < 0 || offset > strlen(fn))
 417                 return EINVAL;
 418
 419         /* special case root directory */
 420         if (*fn == '\0')
 421                 fn = "/";
 422
 423         if (tTd(44, 4))
 424                 sm_dprintf("safedirpath(%s, uid=%ld, gid=%ld, flags=%lx, level=%d, offset=%d):\n",
 425                         fn, (long) uid, (long) gid, flags, level, offset);
 426
 427         if (!bitnset(DBS_GROUPWRITABLEDIRPATHSAFE, DontBlameSendmail))
 428                 mode |= S_IWGRP;
 429
 430         /* Make a modifiable copy of the filename */
 431         if (sm_strlcpy(s, fn, sizeof s) >= sizeof s)
 432                 return EINVAL;
 433
 434         p = s + offset;
 435         while (p != NULL)
 436         {
 437                 /* put back character */
 438                 if (saveptr != NULL)
 439                 {
 440                         *saveptr = save;
 441                         saveptr = NULL;
 442                         p++;
 443                 }
 444
 445                 if (*p == '\0')
 446                         break;
 447
 448                 p = strchr(p, '/');
 449
 450                 /* Special case for root directory */
 451                 if (p == s)
 452                 {
 453                         save = *(p + 1);
 454                         saveptr = p + 1;
 455                         *(p + 1) = '\0';
 456                 }
 457                 else if (p != NULL)
 458                 {
 459                         save = *p;
 460                         saveptr = p;
 461                         *p = '\0';
 462                 }
 463
 464                 /* Heuristic: . and .. have already been checked */
 465                 enddir = strrchr(s, '/');
 466                 if (enddir != NULL &&
 467                     (strcmp(enddir, "/..") == 0 ||
 468                      strcmp(enddir, "/.") == 0))
 469                         continue;
 470
 471                 if (tTd(44, 20))
 472                         sm_dprintf("\t[dir %s]\n", s);
 473
 474 # if HASLSTAT
 475                 ret = lstat(s, &stbuf);
 476 # else /* HASLSTAT */
 477                 ret = stat(s, &stbuf);
 478 # endif /* HASLSTAT */
 479                 if (ret < 0)
 480                 {
 481                         ret = errno;
 482                         break;
 483                 }
 484
 485 # ifdef S_ISLNK
 486                 /* Follow symlinks */
 487                 if (S_ISLNK(stbuf.st_mode))
 488                 {
 489                         int linklen;
 490                         char *target;
 491                         char buf[MAXPATHLEN];
 492                         char fullbuf[MAXLINKPATHLEN];
 493
 494                         memset(buf, '\0', sizeof buf);
 495                         linklen = readlink(s, buf, sizeof buf);
 496                         if (linklen < 0)
 497                         {
 498                                 ret = errno;
 499                                 break;
 500                         }
 501                         if (linklen >= sizeof buf)
 502                         {
 503                                 /* file name too long for buffer */
 504                                 ret = errno = EINVAL;
 505                                 break;
 506                         }
 507
 508                         offset = 0;
 509                         if (*buf == '/')
 510                         {
 511                                 target = buf;
 512
 513                                 /* If path is the same, avoid rechecks */
 514                                 while (s[offset] == buf[offset] &&
 515                                        s[offset] != '\0')
 516                                         offset++;
 517
 518                                 if (s[offset] == '\0' && buf[offset] == '\0')
 519                                 {
 520                                         /* strings match, symlink loop */
 521                                         return ELOOP;
 522                                 }
 523
 524                                 /* back off from the mismatch */
 525                                 if (offset > 0)
 526                                         offset--;
 527
 528                                 /* Make sure we are at a directory break */
 529                                 if (offset > 0 &&
 530                                     s[offset] != '/' &&
 531                                     s[offset] != '\0')
 532                                 {
 533                                         while (buf[offset] != '/' &&
 534                                                offset > 0)
 535                                                 offset--;
 536                                 }
 537                                 if (offset > 0 &&
 538                                     s[offset] == '/' &&
 539                                     buf[offset] == '/')
 540                                 {
 541                                         /* Include the trailing slash */
 542                                         offset++;
 543                                 }
 544                         }
 545                         else
 546                         {
 547                                 char *sptr;
 548
 549                                 sptr = strrchr(s, '/');
 550                                 if (sptr != NULL)
 551                                 {
 552                                         *sptr = '\0';
 553                                         offset = sptr + 1 - s;
 554                                         if (sm_strlcpyn(fullbuf,
 555                                                         sizeof fullbuf, 2,
 556                                                         s, "/") >=
 557                                                 sizeof fullbuf ||
 558                                             sm_strlcat(fullbuf, buf,
 559                                                        sizeof fullbuf) >=
 560                                                 sizeof fullbuf)
 561                                         {
 562                                                 ret = EINVAL;
 563                                                 break;
 564                                         }
 565                                         *sptr = '/';
 566                                 }
 567                                 else
 568                                 {
 569                                         if (sm_strlcpy(fullbuf, buf,
 570                                                        sizeof fullbuf) >=
 571                                                 sizeof fullbuf)
 572                                         {
 573                                                 ret = EINVAL;
 574                                                 break;
 575                                         }
 576                                 }
 577                                 target = fullbuf;
 578                         }
 579                         ret = safedirpath(target, uid, gid, user, flags,
 580                                           level + 1, offset);
 581                         if (ret != 0)
 582                                 break;
 583
 584                         /* Don't check permissions on the link file itself */
 585                         continue;
 586                 }
 587 #endif /* S_ISLNK */
 588
 589                 if ((uid == 0 || bitset(SFF_SAFEDIRPATH, flags)) &&
 590 #ifdef S_ISVTX
 591                     !(bitnset(DBS_TRUSTSTICKYBIT, DontBlameSendmail) &&
 592                       bitset(S_ISVTX, stbuf.st_mode)) &&
 593 #endif /* S_ISVTX */
 594                     bitset(mode, stbuf.st_mode))
 595                 {
 596                         if (tTd(44, 4))
 597                                 sm_dprintf("\t[dir %s] mode %lo ",
 598                                         s, (unsigned long) stbuf.st_mode);
 599                         if (bitset(SFF_SAFEDIRPATH, flags))
 600                         {
 601                                 if (bitset(S_IWOTH, stbuf.st_mode))
 602                                         ret = E_SM_WWDIR;
 603                                 else
 604                                         ret = E_SM_GWDIR;
 605                                 if (tTd(44, 4))
 606                                         sm_dprintf("FATAL\n");
 607                                 break;
 608                         }
 609                         if (tTd(44, 4))
 610                                 sm_dprintf("WARNING\n");
 611                         if (Verbose > 1)
 612                                 message("051 WARNING: %s writable directory %s",
 613                                         bitset(S_IWOTH, stbuf.st_mode)
 614                                            ? "World"
 615                                            : "Group",
 616                                         s);
 617                 }
 618                 if (uid == 0 && !bitset(SFF_ROOTOK|SFF_OPENASROOT, flags))
 619                 {
 620                         if (bitset(S_IXOTH, stbuf.st_mode))
 621                                 continue;
 622                         ret = EACCES;
 623                         break;
 624                 }
 625
 626                 /*
 627                 **  Let OS determine access to file if we are not
 628                 **  running as a privileged user.  This allows ACLs
 629                 **  to work.  Also, if opening as root, assume we can
 630                 **  scan the directory.
 631                 */
 632                 if (geteuid() != 0 || bitset(SFF_OPENASROOT, flags))
 633                         continue;
 634
 635                 if (stbuf.st_uid == uid &&
 636                     bitset(S_IXUSR, stbuf.st_mode))
 637                         continue;
 638                 if (stbuf.st_gid == gid &&
 639                     bitset(S_IXGRP, stbuf.st_mode))
 640                         continue;
 641 # ifndef NO_GROUP_SET
 642                 if (user != NULL && !DontInitGroups &&
 643                     ((gr != NULL && gr->gr_gid == stbuf.st_gid) ||
 644                      (gr = getgrgid(stbuf.st_gid)) != NULL))
 645                 {
 646                         register char **gp;
 647
 648                         for (gp = gr->gr_mem; gp != NULL && *gp != NULL; gp++)
 649                                 if (strcmp(*gp, user) == 0)
 650                                         break;
 651                         if (gp != NULL && *gp != NULL &&
 652                             bitset(S_IXGRP, stbuf.st_mode))
 653                                 continue;
 654                 }
 655 # endif /* ! NO_GROUP_SET */
 656                 if (!bitset(S_IXOTH, stbuf.st_mode))
 657                 {
 658                         ret = EACCES;
 659                         break;
 660                 }
 661         }
 662         if (tTd(44, 4))
 663                 sm_dprintf("\t[dir %s] %s\n", fn,
 664                         ret == 0 ? "OK" : sm_errstring(ret));
 665         return ret;
 666 }
 667 /*
 668 **  SAFEOPEN -- do a file open with extra checking
 669 **
 670 **      Parameters:
 671 **              fn -- the file name to open.
 672 **              omode -- the open-style mode flags.
 673 **              cmode -- the create-style mode flags.
 674 **              sff -- safefile flags.
 675 **
 676 **      Returns:
 677 **              Same as open.
 678 */
 679
 680 int
 681 safeopen(fn, omode, cmode, sff)
 682         char *fn;
 683         int omode;
 684         int cmode;
 685         long sff;
 686 {
 687 #if !NOFTRUNCATE
 688         bool truncate;
 689 #endif /* !NOFTRUNCATE */
 690         int rval;
 691         int fd;
 692         int smode;
 693         struct stat stb;
 694
 695         if (tTd(44, 10))
 696                 sm_dprintf("safeopen: fn=%s, omode=%x, cmode=%x, sff=%lx\n",
 697                            fn, omode, cmode, sff);
 698
 699         if (bitset(O_CREAT, omode))
 700                 sff |= SFF_CREAT;
 701         omode &= ~O_CREAT;
 702         switch (omode & O_ACCMODE)
 703         {
 704           case O_RDONLY:
 705                 smode = S_IREAD;
 706                 break;
 707
 708           case O_WRONLY:
 709                 smode = S_IWRITE;
 710                 break;
 711
 712           case O_RDWR:
 713                 smode = S_IREAD|S_IWRITE;
 714                 break;
 715
 716           default:
 717                 smode = 0;
 718                 break;
 719         }
 720         if (bitset(SFF_OPENASROOT, sff))
 721                 rval = safefile(fn, RunAsUid, RunAsGid, RunAsUserName,
 722                                 sff, smode, &stb);
 723         else
 724                 rval = safefile(fn, RealUid, RealGid, RealUserName,
 725                                 sff, smode, &stb);
 726         if (rval != 0)
 727         {
 728                 errno = rval;
 729                 return -1;
 730         }
 731         if (stb.st_mode == ST_MODE_NOFILE && bitset(SFF_CREAT, sff))
 732                 omode |= O_CREAT | (bitset(SFF_NOTEXCL, sff) ? 0 : O_EXCL);
 733         else if (bitset(SFF_CREAT, sff) && bitset(O_EXCL, omode))
 734         {
 735                 /* The file exists so an exclusive create would fail */
 736                 errno = EEXIST;
 737                 return -1;
 738         }
 739
 740 #if !NOFTRUNCATE
 741         truncate = bitset(O_TRUNC, omode);
 742         if (truncate)
 743                 omode &= ~O_TRUNC;
 744 #endif /* !NOFTRUNCATE */
 745
 746         fd = dfopen(fn, omode, cmode, sff);
 747         if (fd < 0)
 748                 return fd;
 749         if (filechanged(fn, fd, &stb))
 750         {
 751                 syserr("554 5.3.0 cannot open: file %s changed after open", fn);
 752                 (void) close(fd);
 753                 errno = E_SM_FILECHANGE;
 754                 return -1;
 755         }
 756
 757 #if !NOFTRUNCATE
 758         if (truncate &&
 759             ftruncate(fd, (off_t) 0) < 0)
 760         {
 761                 int save_errno;
 762
 763                 save_errno = errno;
 764                 syserr("554 5.3.0 cannot open: file %s could not be truncated",
 765                        fn);
 766                 (void) close(fd);
 767                 errno = save_errno;
 768                 return -1;
 769         }
 770 #endif /* !NOFTRUNCATE */
 771
 772         return fd;
 773 }
 774 /*
 775 **  SAFEFOPEN -- do a file open with extra checking
 776 **
 777 **      Parameters:
 778 **              fn -- the file name to open.
 779 **              omode -- the open-style mode flags.
 780 **              cmode -- the create-style mode flags.
 781 **              sff -- safefile flags.
 782 **
 783 **      Returns:
 784 **              Same as fopen.
 785 */
 786
 787 SM_FILE_T *
 788 safefopen(fn, omode, cmode, sff)
 789         char *fn;
 790         int omode;
 791         int cmode;
 792         long sff;
 793 {
 794         int fd;
 795         int save_errno;
 796         SM_FILE_T *fp;
 797         int fmode;
 798
 799         switch (omode & O_ACCMODE)
 800         {
 801           case O_RDONLY:
 802                 fmode = SM_IO_RDONLY;
 803                 break;
 804
 805           case O_WRONLY:
 806                 if (bitset(O_APPEND, omode))
 807                         fmode = SM_IO_APPEND;
 808                 else
 809                         fmode = SM_IO_WRONLY;
 810                 break;
 811
 812           case O_RDWR:
 813                 if (bitset(O_TRUNC, omode))
 814                         fmode = SM_IO_RDWRTR;
 815                 else if (bitset(O_APPEND, omode))
 816                         fmode = SM_IO_APPENDRW;
 817                 else
 818                         fmode = SM_IO_RDWR;
 819                 break;
 820
 821           default:
 822                 syserr("554 5.3.5 safefopen: unknown omode %o", omode);
 823                 fmode = 0;
 824         }
 825         fd = safeopen(fn, omode, cmode, sff);
 826         if (fd < 0)
 827         {
 828                 save_errno = errno;
 829                 if (tTd(44, 10))
 830                         sm_dprintf("safefopen: safeopen failed: %s\n",
 831                                    sm_errstring(errno));
 832                 errno = save_errno;
 833                 return NULL;
 834         }
 835         fp = sm_io_open(SmFtStdiofd, SM_TIME_DEFAULT,
 836                         (void *) &fd, fmode, NULL);
 837         if (fp != NULL)
 838                 return fp;
 839
 840         save_errno = errno;
 841         if (tTd(44, 10))
 842         {
 843                 sm_dprintf("safefopen: fdopen(%s, %d) failed: omode=%x, sff=%lx, err=%s\n",
 844                            fn, fmode, omode, sff, sm_errstring(errno));
 845         }
 846         (void) close(fd);
 847         errno = save_errno;
 848         return NULL;
 849 }
 850 /*
 851 **  FILECHANGED -- check to see if file changed after being opened
 852 **
 853 **      Parameters:
 854 **              fn -- pathname of file to check.
 855 **              fd -- file descriptor to check.
 856 **              stb -- stat structure from before open.
 857 **
 858 **      Returns:
 859 **              true -- if a problem was detected.
 860 **              false -- if this file is still the same.
 861 */
 862
 863 bool
 864 filechanged(fn, fd, stb)
 865         char *fn;
 866         int fd;
 867         struct stat *stb;
 868 {
 869         struct stat sta;
 870
 871         if (stb->st_mode == ST_MODE_NOFILE)
 872         {
 873 # if HASLSTAT && BOGUS_O_EXCL
 874                 /* only necessary if exclusive open follows symbolic links */
 875                 if (lstat(fn, stb) < 0 || stb->st_nlink != 1)
 876                         return true;
 877 # else /* HASLSTAT && BOGUS_O_EXCL */
 878                 return false;
 879 # endif /* HASLSTAT && BOGUS_O_EXCL */
 880         }
 881         if (fstat(fd, &sta) < 0)
 882                 return true;
 883
 884         if (sta.st_nlink != stb->st_nlink ||
 885             sta.st_dev != stb->st_dev ||
 886             sta.st_ino != stb->st_ino ||
 887 # if HAS_ST_GEN && 0            /* AFS returns garbage in st_gen */
 888             sta.st_gen != stb->st_gen ||
 889 # endif /* HAS_ST_GEN && 0 */
 890             sta.st_uid != stb->st_uid ||
 891             sta.st_gid != stb->st_gid)
 892         {
 893                 if (tTd(44, 8))
 894                 {
 895                         sm_dprintf("File changed after opening:\n");
 896                         sm_dprintf(" nlink      = %ld/%ld\n",
 897                                 (long) stb->st_nlink, (long) sta.st_nlink);
 898                         sm_dprintf(" dev        = %ld/%ld\n",
 899                                 (long) stb->st_dev, (long) sta.st_dev);
 900                         sm_dprintf(" ino        = %llu/%llu\n",
 901                                 (ULONGLONG_T) stb->st_ino,
 902                                 (ULONGLONG_T) sta.st_ino);
 903 # if HAS_ST_GEN
 904                         sm_dprintf(" gen        = %ld/%ld\n",
 905                                 (long) stb->st_gen, (long) sta.st_gen);
 906 # endif /* HAS_ST_GEN */
 907                         sm_dprintf(" uid        = %ld/%ld\n",
 908                                 (long) stb->st_uid, (long) sta.st_uid);
 909                         sm_dprintf(" gid        = %ld/%ld\n",
 910                                 (long) stb->st_gid, (long) sta.st_gid);
 911                 }
 912                 return true;
 913         }
 914
 915         return false;
 916 }
 917 /*
 918 **  DFOPEN -- determined file open
 919 **
 920 **      This routine has the semantics of open, except that it will
 921 **      keep trying a few times to make this happen.  The idea is that
 922 **      on very loaded systems, we may run out of resources (inodes,
 923 **      whatever), so this tries to get around it.
 924 */
 925
 926 int
 927 dfopen(filename, omode, cmode, sff)
 928         char *filename;
 929         int omode;
 930         int cmode;
 931         long sff;
 932 {
 933         register int tries;
 934         int fd = -1;
 935         struct stat st;
 936
 937         for (tries = 0; tries < 10; tries++)
 938         {
 939                 (void) sleep((unsigned) (10 * tries));
 940                 errno = 0;
 941                 fd = open(filename, omode, cmode);
 942                 if (fd >= 0)
 943                         break;
 944                 switch (errno)
 945                 {
 946                   case ENFILE:          /* system file table full */
 947                   case EINTR:           /* interrupted syscall */
 948 #ifdef ETXTBSY
 949                   case ETXTBSY:         /* Apollo: net file locked */
 950 #endif /* ETXTBSY */
 951                         continue;
 952                 }
 953                 break;
 954         }
 955         if (!bitset(SFF_NOLOCK, sff) &&
 956             fd >= 0 &&
 957             fstat(fd, &st) >= 0 &&
 958             S_ISREG(st.st_mode))
 959         {
 960                 int locktype;
 961
 962                 /* lock the file to avoid accidental conflicts */
 963                 if ((omode & O_ACCMODE) != O_RDONLY)
 964                         locktype = LOCK_EX;
 965                 else
 966                         locktype = LOCK_SH;
 967                 if (bitset(SFF_NBLOCK, sff))
 968                         locktype |= LOCK_NB;
 969
 970                 if (!lockfile(fd, filename, NULL, locktype))
 971                 {
 972                         int save_errno = errno;
 973
 974                         (void) close(fd);
 975                         fd = -1;
 976                         errno = save_errno;
 977                 }
 978                 else
 979                         errno = 0;
 980         }
 981         return fd;
 982 }