libutil/gr_util.c

   1 /*-
   2  * Copyright (c) 2008 Sean C. Farley <scf@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer,
  10  *    without modification, immediately at the beginning of the file.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 #include <sys/param.h>
  31 #include <sys/errno.h>
  32 #include <sys/stat.h>
  33
  34 #include <ctype.h>
  35 #include <err.h>
  36 #include <fcntl.h>
  37 #include <grp.h>
  38 #include <inttypes.h>
  39 #include <libutil.h>
  40 #include <paths.h>
  41 #include <stdbool.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <unistd.h>
  46
  47 struct group_storage {
  48         struct group     gr;
  49         char            *members[];
  50 };
  51
  52 static int lockfd = -1;
  53 static char group_dir[PATH_MAX];
  54 static char group_file[PATH_MAX];
  55 static char tempname[PATH_MAX];
  56 static int initialized;
  57
  58 static const char group_line_format[] = "%s:%s:%ju:";
  59
  60 /*
  61  * Initialize statics
  62  */
  63 int
  64 gr_init(const char *dir, const char *group)
  65 {
  66         if (dir == NULL) {
  67                 strcpy(group_dir, _PATH_ETC);
  68         } else {
  69                 if (strlen(dir) >= sizeof(group_dir)) {
  70                         errno = ENAMETOOLONG;
  71                         return (-1);
  72                 }
  73                 strcpy(group_dir, dir);
  74         }
  75
  76         if (group == NULL) {
  77                 if (dir == NULL) {
  78                         strcpy(group_file, _PATH_GROUP);
  79                 } else if (snprintf(group_file, sizeof(group_file), "%s/group",
  80                         group_dir) > (int)sizeof(group_file)) {
  81                         errno = ENAMETOOLONG;
  82                         return (-1);
  83                 }
  84         } else {
  85                 if (strlen(group) >= sizeof(group_file)) {
  86                         errno = ENAMETOOLONG;
  87                         return (-1);
  88                 }
  89                 strcpy(group_file, group);
  90         }
  91         initialized = 1;
  92         return (0);
  93 }
  94
  95 /*
  96  * Lock the group file
  97  */
  98 int
  99 gr_lock(void)
 100 {
 101         if (*group_file == '\0')
 102                 return (-1);
 103
 104         for (;;) {
 105                 struct stat st;
 106
 107                 lockfd = open(group_file, O_RDONLY, 0);
 108                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 109                         err(1, "%s", group_file);
 110                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 111                         if (errno == EWOULDBLOCK) {
 112                                 errx(1, "the group file is busy");
 113                         } else {
 114                                 err(1, "could not lock the group file: ");
 115                         }
 116                 }
 117                 if (fstat(lockfd, &st) == -1)
 118                         err(1, "fstat() failed: ");
 119                 if (st.st_nlink != 0)
 120                         break;
 121                 close(lockfd);
 122                 lockfd = -1;
 123         }
 124         return (lockfd);
 125 }
 126
 127 /*
 128  * Create and open a presmuably safe temp file for editing group data
 129  */
 130 int
 131 gr_tmp(int mfd)
 132 {
 133         char buf[8192];
 134         ssize_t nr;
 135         const char *p;
 136         int tfd;
 137
 138         if (*group_file == '\0')
 139                 return (-1);
 140         if ((p = strrchr(group_file, '/')))
 141                 ++p;
 142         else
 143                 p = group_file;
 144         if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
 145                 (int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
 146                 errno = ENAMETOOLONG;
 147                 return (-1);
 148         }
 149         if ((tfd = mkstemp(tempname)) == -1)
 150                 return (-1);
 151         if (mfd != -1) {
 152                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 153                         if (write(tfd, buf, (size_t)nr) != nr)
 154                                 break;
 155                 if (nr != 0) {
 156                         unlink(tempname);
 157                         *tempname = '\0';
 158                         close(tfd);
 159                         return (-1);
 160                 }
 161         }
 162         return (tfd);
 163 }
 164
 165 /*
 166  * Copy the group file from one descriptor to another, replacing, deleting
 167  * or adding a single record on the way.
 168  */
 169 int
 170 gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
 171 {
 172         char buf[8192], *end, *line, *p, *q, *r, t;
 173         struct group *fgr;
 174         const struct group *sgr;
 175         size_t len;
 176         int eof, readlen;
 177
 178         sgr = gr;
 179         if (gr == NULL) {
 180                 line = NULL;
 181                 if (old_gr == NULL)
 182                         return (-1);
 183                 sgr = old_gr;
 184         } else if ((line = gr_make(gr)) == NULL)
 185                 return (-1);
 186
 187         eof = 0;
 188         len = 0;
 189         p = q = end = buf;
 190         for (;;) {
 191                 /* find the end of the current line */
 192                 for (p = q; q < end && *q != '\0'; ++q)
 193                         if (*q == '\n')
 194                                 break;
 195
 196                 /* if we don't have a complete line, fill up the buffer */
 197                 if (q >= end) {
 198                         if (eof)
 199                                 break;
 200                         if ((size_t)(q - p) >= sizeof(buf)) {
 201                                 warnx("group line too long");
 202                                 errno = EINVAL; /* hack */
 203                                 goto err;
 204                         }
 205                         if (p < end) {
 206                                 q = memmove(buf, p, end -p);
 207                                 end -= p - buf;
 208                         } else {
 209                                 p = q = end = buf;
 210                         }
 211                         readlen = read(ffd, end, sizeof(buf) - (end -buf));
 212                         if (readlen == -1)
 213                                 goto err;
 214                         else
 215                                 len = (size_t)readlen;
 216                         if (len == 0 && p == buf)
 217                                 break;
 218                         end += len;
 219                         len = end - buf;
 220                         if (len < (ssize_t)sizeof(buf)) {
 221                                 eof = 1;
 222                                 if (len > 0 && buf[len -1] != '\n')
 223                                         ++len, *end++ = '\n';
 224                         }
 225                         continue;
 226                 }
 227
 228                 /* is it a blank line or a comment? */
 229                 for (r = p; r < q && isspace(*r); ++r)
 230                         /* nothing */;
 231                 if (r == q || *r == '#') {
 232                         /* yep */
 233                         if (write(tfd, p, q -p + 1) != q - p + 1)
 234                                 goto err;
 235                         ++q;
 236                         continue;
 237                 }
 238
 239                 /* is it the one we're looking for? */
 240
 241                 t = *q;
 242                 *q = '\0';
 243
 244                 fgr = gr_scan(r);
 245
 246                 /* fgr is either a struct group for the current line,
 247                  * or NULL if the line is malformed.
 248                  */
 249
 250                 *q = t;
 251                 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
 252                         /* nope */
 253                         if (fgr != NULL)
 254                                 free(fgr);
 255                         if (write(tfd, p, q - p + 1) != q - p + 1)
 256                                 goto err;
 257                         ++q;
 258                         continue;
 259                 }
 260                 if (old_gr && !gr_equal(fgr, old_gr)) {
 261                         warnx("entry inconsistent");
 262                         free(fgr);
 263                         errno = EINVAL; /* hack */
 264                         goto err;
 265                 }
 266                 free(fgr);
 267
 268                 /* it is, replace or remove it */
 269                 if (line != NULL) {
 270                         len = strlen(line);
 271                         if (write(tfd, line, len) != (int) len)
 272                                 goto err;
 273                 } else {
 274                         /* when removed, avoid the \n */
 275                         q++;
 276                 }
 277                 /* we're done, just copy the rest over */
 278                 for (;;) {
 279                         if (write(tfd, q, end - q) != end - q)
 280                                 goto err;
 281                         q = buf;
 282                         readlen = read(ffd, buf, sizeof(buf));
 283                         if (readlen == 0)
 284                                 break;
 285                         else
 286                                 len = (size_t)readlen;
 287                         if (readlen == -1)
 288                                 goto err;
 289                         end = buf + len;
 290                 }
 291                 goto done;
 292         }
 293
 294         /* if we got here, we didn't find the old entry */
 295         if (line == NULL) {
 296                 errno = ENOENT;
 297                 goto err;
 298         }
 299         len = strlen(line);
 300         if ((size_t)write(tfd, line, len) != len ||
 301            write(tfd, "\n", 1) != 1)
 302                 goto err;
 303  done:
 304         if (line != NULL)
 305                 free(line);
 306         return (0);
 307  err:
 308         if (line != NULL)
 309                 free(line);
 310         return (-1);
 311 }
 312
 313 /*
 314  * Regenerate the group file
 315  */
 316 int
 317 gr_mkdb(void)
 318 {
 319         return (rename(tempname, group_file));
 320 }
 321
 322 /*
 323  * Clean up. Preserver errno for the caller's convenience.
 324  */
 325 void
 326 gr_fini(void)
 327 {
 328         int serrno;
 329
 330         if (!initialized)
 331                 return;
 332         initialized = 0;
 333         serrno = errno;
 334         if (*tempname != '\0') {
 335                 unlink(tempname);
 336                 *tempname = '\0';
 337         }
 338         if (lockfd != -1)
 339                 close(lockfd);
 340         errno = serrno;
 341 }
 342
 343 /*
 344  * Compares two struct group's.
 345  */
 346 int
 347 gr_equal(const struct group *gr1, const struct group *gr2)
 348 {
 349         int gr1_ndx;
 350         int gr2_ndx;
 351         bool found;
 352
 353         /* Check that the non-member information is the same. */
 354         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 355                 if (gr1->gr_name != gr2->gr_name)
 356                         return (false);
 357         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 358                 return (false);
 359         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 360                 if (gr1->gr_passwd != gr2->gr_passwd)
 361                         return (false);
 362         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 363                 return (false);
 364         if (gr1->gr_gid != gr2->gr_gid)
 365                 return (false);
 366
 367         /* Check all members in both groups. */
 368         if (gr1->gr_mem == NULL || gr2->gr_mem == NULL) {
 369                 if (gr1->gr_mem != gr2->gr_mem)
 370                         return (false);
 371         } else {
 372                 for (found = false, gr1_ndx = 0; gr1->gr_mem[gr1_ndx] != NULL;
 373                     gr1_ndx++) {
 374                         for (gr2_ndx = 0; gr2->gr_mem[gr2_ndx] != NULL;
 375                             gr2_ndx++)
 376                                 if (strcmp(gr1->gr_mem[gr1_ndx],
 377                                     gr2->gr_mem[gr2_ndx]) == 0) {
 378                                         found = true;
 379                                         break;
 380                                 }
 381                         if (!found)
 382                                 return (false);
 383                 }
 384
 385                 /* Check that group2 does not have more members than group1. */
 386                 if (gr2->gr_mem[gr1_ndx] != NULL)
 387                         return (false);
 388         }
 389
 390         return (true);
 391 }
 392
 393 /*
 394  * Make a group line out of a struct group.
 395  */
 396 char *
 397 gr_make(const struct group *gr)
 398 {
 399         char *line;
 400         size_t line_size;
 401         int ndx;
 402
 403         /* Calculate the length of the group line. */
 404         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 405             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 406         if (gr->gr_mem != NULL) {
 407                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 408                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 409                 if (ndx > 0)
 410                         line_size--;
 411         }
 412
 413         /* Create the group line and fill it. */
 414         if ((line = malloc(line_size)) == NULL)
 415                 return (NULL);
 416         snprintf(line, line_size, group_line_format, gr->gr_name, gr->gr_passwd,
 417             (uintmax_t)gr->gr_gid);
 418         if (gr->gr_mem != NULL)
 419                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 420                         strcat(line, gr->gr_mem[ndx]);
 421                         if (gr->gr_mem[ndx + 1] != NULL)
 422                                 strcat(line, ",");
 423                 }
 424
 425         return (line);
 426 }
 427
 428 /*
 429  * Duplicate a struct group.
 430  */
 431 struct group *
 432 gr_dup(const struct group *gr)
 433 {
 434         char *dst;
 435         size_t len;
 436         struct group_storage *gs;
 437         int ndx;
 438         int num_mem;
 439
 440         /* Calculate size of the group. */
 441         len = sizeof(*gs);
 442         if (gr->gr_name != NULL)
 443                 len += strlen(gr->gr_name) + 1;
 444         if (gr->gr_passwd != NULL)
 445                 len += strlen(gr->gr_passwd) + 1;
 446         if (gr->gr_mem != NULL) {
 447                 for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++)
 448                         len += strlen(gr->gr_mem[num_mem]) + 1;
 449                 len += (num_mem + 1) * sizeof(*gr->gr_mem);
 450         } else
 451                 num_mem = -1;
 452
 453         /* Create new group and copy old group into it. */
 454         if ((gs = calloc(1, len)) == NULL)
 455                 return (NULL);
 456         dst = (char *)&gs->members[num_mem + 1];
 457         if (gr->gr_name != NULL) {
 458                 gs->gr.gr_name = dst;
 459                 dst = stpcpy(gs->gr.gr_name, gr->gr_name) + 1;
 460         }
 461         if (gr->gr_passwd != NULL) {
 462                 gs->gr.gr_passwd = dst;
 463                 dst = stpcpy(gs->gr.gr_passwd, gr->gr_passwd) + 1;
 464         }
 465         gs->gr.gr_gid = gr->gr_gid;
 466         if (gr->gr_mem != NULL) {
 467                 gs->gr.gr_mem = gs->members;
 468                 for (ndx = 0; ndx < num_mem; ndx++) {
 469                         gs->gr.gr_mem[ndx] = dst;
 470                         dst = stpcpy(gs->gr.gr_mem[ndx], gr->gr_mem[ndx]) + 1;
 471                 }
 472                 gs->gr.gr_mem[ndx] = NULL;
 473         }
 474
 475         return (&gs->gr);
 476 }
 477
 478 /*
 479  * Scan a line and place it into a group structure.
 480  */
 481 static bool
 482 __gr_scan(char *line, struct group *gr)
 483 {
 484         char *loc;
 485         int ndx;
 486
 487         /* Assign non-member information to structure. */
 488         gr->gr_name = line;
 489         if ((loc = strchr(line, ':')) == NULL)
 490                 return (false);
 491         *loc = '\0';
 492         gr->gr_passwd = loc + 1;
 493         if (*gr->gr_passwd == ':')
 494                 *gr->gr_passwd = '\0';
 495         else {
 496                 if ((loc = strchr(loc + 1, ':')) == NULL)
 497                         return (false);
 498                 *loc = '\0';
 499         }
 500         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 501                 return (false);
 502
 503         /* Assign member information to structure. */
 504         if ((loc = strchr(loc + 1, ':')) == NULL)
 505                 return (false);
 506         line = loc + 1;
 507         gr->gr_mem = NULL;
 508         ndx = 0;
 509         do {
 510                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 511                     (ndx + 1));
 512                 if (gr->gr_mem == NULL)
 513                         return (false);
 514
 515                 /* Skip locations without members (i.e., empty string). */
 516                 do {
 517                         gr->gr_mem[ndx] = strsep(&line, ",");
 518                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 519         } while (gr->gr_mem[ndx++] != NULL);
 520
 521         return (true);
 522 }
 523
 524 /*
 525  * Create a struct group from a line.
 526  */
 527 struct group *
 528 gr_scan(const char *line)
 529 {
 530         struct group gr;
 531         char *line_copy;
 532         struct group *new_gr;
 533
 534         if ((line_copy = strdup(line)) == NULL)
 535                 return (NULL);
 536         if (!__gr_scan(line_copy, &gr)) {
 537                 free(line_copy);
 538                 return (NULL);
 539         }
 540         new_gr = gr_dup(&gr);
 541         free(line_copy);
 542         if (gr.gr_mem != NULL)
 543                 free(gr.gr_mem);
 544
 545         return (new_gr);
 546 }