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         struct stat st;
  67
  68         if (dir == NULL) {
  69                 strcpy(group_dir, _PATH_ETC);
  70         } else {
  71                 if (strlen(dir) >= sizeof(group_dir)) {
  72                         errno = ENAMETOOLONG;
  73                         return (-1);
  74                 }
  75                 strcpy(group_dir, dir);
  76         }
  77
  78         if (group == NULL) {
  79                 if (dir == NULL) {
  80                         strcpy(group_file, _PATH_GROUP);
  81                 } else if (snprintf(group_file, sizeof(group_file), "%s/group",
  82                         group_dir) > (int)sizeof(group_file)) {
  83                         errno = ENAMETOOLONG;
  84                         return (-1);
  85                 }
  86         } else {
  87                 if (strlen(group) >= sizeof(group_file)) {
  88                         errno = ENAMETOOLONG;
  89                         return (-1);
  90                 }
  91                 strcpy(group_file, group);
  92         }
  93
  94         if (stat(group_file, &st) == -1)
  95                 return (-1);
  96
  97         if (S_ISDIR(st.st_mode)) {
  98                 errno = EISDIR;
  99                 return (-1);
 100         }
 101
 102         initialized = 1;
 103         return (0);
 104 }
 105
 106 /*
 107  * Lock the group file
 108  */
 109 int
 110 gr_lock(void)
 111 {
 112         if (*group_file == '\0')
 113                 return (-1);
 114
 115         for (;;) {
 116                 struct stat st;
 117
 118                 lockfd = open(group_file, O_RDONLY, 0);
 119                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 120                         err(1, "%s", group_file);
 121                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 122                         if (errno == EWOULDBLOCK) {
 123                                 errx(1, "the group file is busy");
 124                         } else {
 125                                 err(1, "could not lock the group file: ");
 126                         }
 127                 }
 128                 if (fstat(lockfd, &st) == -1)
 129                         err(1, "fstat() failed: ");
 130                 if (st.st_nlink != 0)
 131                         break;
 132                 close(lockfd);
 133                 lockfd = -1;
 134         }
 135         return (lockfd);
 136 }
 137
 138 /*
 139  * Create and open a presmuably safe temp file for editing group data
 140  */
 141 int
 142 gr_tmp(int mfd)
 143 {
 144         char buf[8192];
 145         ssize_t nr;
 146         const char *p;
 147         int tfd;
 148
 149         if (*group_file == '\0')
 150                 return (-1);
 151         if ((p = strrchr(group_file, '/')))
 152                 ++p;
 153         else
 154                 p = group_file;
 155         if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
 156                 (int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
 157                 errno = ENAMETOOLONG;
 158                 return (-1);
 159         }
 160         if ((tfd = mkstemp(tempname)) == -1)
 161                 return (-1);
 162         if (mfd != -1) {
 163                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 164                         if (write(tfd, buf, (size_t)nr) != nr)
 165                                 break;
 166                 if (nr != 0) {
 167                         unlink(tempname);
 168                         *tempname = '\0';
 169                         close(tfd);
 170                         return (-1);
 171                 }
 172         }
 173         return (tfd);
 174 }
 175
 176 /*
 177  * Copy the group file from one descriptor to another, replacing, deleting
 178  * or adding a single record on the way.
 179  */
 180 int
 181 gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
 182 {
 183         char buf[8192], *end, *line, *p, *q, *r, t;
 184         struct group *fgr;
 185         const struct group *sgr;
 186         size_t len;
 187         int eof, readlen;
 188
 189         sgr = gr;
 190         if (gr == NULL) {
 191                 line = NULL;
 192                 if (old_gr == NULL)
 193                         return (-1);
 194                 sgr = old_gr;
 195         } else if ((line = gr_make(gr)) == NULL)
 196                 return (-1);
 197
 198         eof = 0;
 199         len = 0;
 200         p = q = end = buf;
 201         for (;;) {
 202                 /* find the end of the current line */
 203                 for (p = q; q < end && *q != '\0'; ++q)
 204                         if (*q == '\n')
 205                                 break;
 206
 207                 /* if we don't have a complete line, fill up the buffer */
 208                 if (q >= end) {
 209                         if (eof)
 210                                 break;
 211                         if ((size_t)(q - p) >= sizeof(buf)) {
 212                                 warnx("group line too long");
 213                                 errno = EINVAL; /* hack */
 214                                 goto err;
 215                         }
 216                         if (p < end) {
 217                                 q = memmove(buf, p, end -p);
 218                                 end -= p - buf;
 219                         } else {
 220                                 p = q = end = buf;
 221                         }
 222                         readlen = read(ffd, end, sizeof(buf) - (end -buf));
 223                         if (readlen == -1)
 224                                 goto err;
 225                         else
 226                                 len = (size_t)readlen;
 227                         if (len == 0 && p == buf)
 228                                 break;
 229                         end += len;
 230                         len = end - buf;
 231                         if (len < (ssize_t)sizeof(buf)) {
 232                                 eof = 1;
 233                                 if (len > 0 && buf[len -1] != '\n')
 234                                         ++len, *end++ = '\n';
 235                         }
 236                         continue;
 237                 }
 238
 239                 /* is it a blank line or a comment? */
 240                 for (r = p; r < q && isspace(*r); ++r)
 241                         /* nothing */;
 242                 if (r == q || *r == '#') {
 243                         /* yep */
 244                         if (write(tfd, p, q -p + 1) != q - p + 1)
 245                                 goto err;
 246                         ++q;
 247                         continue;
 248                 }
 249
 250                 /* is it the one we're looking for? */
 251
 252                 t = *q;
 253                 *q = '\0';
 254
 255                 fgr = gr_scan(r);
 256
 257                 /* fgr is either a struct group for the current line,
 258                  * or NULL if the line is malformed.
 259                  */
 260
 261                 *q = t;
 262                 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
 263                         /* nope */
 264                         if (fgr != NULL)
 265                                 free(fgr);
 266                         if (write(tfd, p, q - p + 1) != q - p + 1)
 267                                 goto err;
 268                         ++q;
 269                         continue;
 270                 }
 271                 if (old_gr && !gr_equal(fgr, old_gr)) {
 272                         warnx("entry inconsistent");
 273                         free(fgr);
 274                         errno = EINVAL; /* hack */
 275                         goto err;
 276                 }
 277                 free(fgr);
 278
 279                 /* it is, replace or remove it */
 280                 if (line != NULL) {
 281                         len = strlen(line);
 282                         if (write(tfd, line, len) != (int) len)
 283                                 goto err;
 284                 } else {
 285                         /* when removed, avoid the \n */
 286                         q++;
 287                 }
 288                 /* we're done, just copy the rest over */
 289                 for (;;) {
 290                         if (write(tfd, q, end - q) != end - q)
 291                                 goto err;
 292                         q = buf;
 293                         readlen = read(ffd, buf, sizeof(buf));
 294                         if (readlen == 0)
 295                                 break;
 296                         else
 297                                 len = (size_t)readlen;
 298                         if (readlen == -1)
 299                                 goto err;
 300                         end = buf + len;
 301                 }
 302                 goto done;
 303         }
 304
 305         /* if we got here, we didn't find the old entry */
 306         if (line == NULL) {
 307                 errno = ENOENT;
 308                 goto err;
 309         }
 310         len = strlen(line);
 311         if ((size_t)write(tfd, line, len) != len ||
 312            write(tfd, "\n", 1) != 1)
 313                 goto err;
 314  done:
 315         if (line != NULL)
 316                 free(line);
 317         return (0);
 318  err:
 319         if (line != NULL)
 320                 free(line);
 321         return (-1);
 322 }
 323
 324 /*
 325  * Regenerate the group file
 326  */
 327 int
 328 gr_mkdb(void)
 329 {
 330         return (rename(tempname, group_file));
 331 }
 332
 333 /*
 334  * Clean up. Preserver errno for the caller's convenience.
 335  */
 336 void
 337 gr_fini(void)
 338 {
 339         int serrno;
 340
 341         if (!initialized)
 342                 return;
 343         initialized = 0;
 344         serrno = errno;
 345         if (*tempname != '\0') {
 346                 unlink(tempname);
 347                 *tempname = '\0';
 348         }
 349         if (lockfd != -1)
 350                 close(lockfd);
 351         errno = serrno;
 352 }
 353
 354 /*
 355  * Compares two struct group's.
 356  */
 357 int
 358 gr_equal(const struct group *gr1, const struct group *gr2)
 359 {
 360         int gr1_ndx;
 361         int gr2_ndx;
 362         bool found;
 363
 364         /* Check that the non-member information is the same. */
 365         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 366                 if (gr1->gr_name != gr2->gr_name)
 367                         return (false);
 368         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 369                 return (false);
 370         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 371                 if (gr1->gr_passwd != gr2->gr_passwd)
 372                         return (false);
 373         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 374                 return (false);
 375         if (gr1->gr_gid != gr2->gr_gid)
 376                 return (false);
 377
 378         /* Check all members in both groups. */
 379         if (gr1->gr_mem == NULL || gr2->gr_mem == NULL) {
 380                 if (gr1->gr_mem != gr2->gr_mem)
 381                         return (false);
 382         } else {
 383                 for (found = false, gr1_ndx = 0; gr1->gr_mem[gr1_ndx] != NULL;
 384                     gr1_ndx++) {
 385                         for (gr2_ndx = 0; gr2->gr_mem[gr2_ndx] != NULL;
 386                             gr2_ndx++)
 387                                 if (strcmp(gr1->gr_mem[gr1_ndx],
 388                                     gr2->gr_mem[gr2_ndx]) == 0) {
 389                                         found = true;
 390                                         break;
 391                                 }
 392                         if (!found)
 393                                 return (false);
 394                 }
 395
 396                 /* Check that group2 does not have more members than group1. */
 397                 if (gr2->gr_mem[gr1_ndx] != NULL)
 398                         return (false);
 399         }
 400
 401         return (true);
 402 }
 403
 404 /*
 405  * Make a group line out of a struct group.
 406  */
 407 char *
 408 gr_make(const struct group *gr)
 409 {
 410         char *line;
 411         size_t line_size;
 412         int ndx;
 413
 414         /* Calculate the length of the group line. */
 415         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 416             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 417         if (gr->gr_mem != NULL) {
 418                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 419                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 420                 if (ndx > 0)
 421                         line_size--;
 422         }
 423
 424         /* Create the group line and fill it. */
 425         if ((line = malloc(line_size)) == NULL)
 426                 return (NULL);
 427         snprintf(line, line_size, group_line_format, gr->gr_name, gr->gr_passwd,
 428             (uintmax_t)gr->gr_gid);
 429         if (gr->gr_mem != NULL)
 430                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 431                         strcat(line, gr->gr_mem[ndx]);
 432                         if (gr->gr_mem[ndx + 1] != NULL)
 433                                 strcat(line, ",");
 434                 }
 435
 436         return (line);
 437 }
 438
 439 /*
 440  * Duplicate a struct group.
 441  */
 442 struct group *
 443 gr_dup(const struct group *gr)
 444 {
 445         char *dst;
 446         size_t len;
 447         struct group_storage *gs;
 448         int ndx;
 449         int num_mem;
 450
 451         /* Calculate size of the group. */
 452         len = sizeof(*gs);
 453         if (gr->gr_name != NULL)
 454                 len += strlen(gr->gr_name) + 1;
 455         if (gr->gr_passwd != NULL)
 456                 len += strlen(gr->gr_passwd) + 1;
 457         if (gr->gr_mem != NULL) {
 458                 for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++)
 459                         len += strlen(gr->gr_mem[num_mem]) + 1;
 460                 len += (num_mem + 1) * sizeof(*gr->gr_mem);
 461         } else
 462                 num_mem = -1;
 463
 464         /* Create new group and copy old group into it. */
 465         if ((gs = calloc(1, len)) == NULL)
 466                 return (NULL);
 467         dst = (char *)&gs->members[num_mem + 1];
 468         if (gr->gr_name != NULL) {
 469                 gs->gr.gr_name = dst;
 470                 dst = stpcpy(gs->gr.gr_name, gr->gr_name) + 1;
 471         }
 472         if (gr->gr_passwd != NULL) {
 473                 gs->gr.gr_passwd = dst;
 474                 dst = stpcpy(gs->gr.gr_passwd, gr->gr_passwd) + 1;
 475         }
 476         gs->gr.gr_gid = gr->gr_gid;
 477         if (gr->gr_mem != NULL) {
 478                 gs->gr.gr_mem = gs->members;
 479                 for (ndx = 0; ndx < num_mem; ndx++) {
 480                         gs->gr.gr_mem[ndx] = dst;
 481                         dst = stpcpy(gs->gr.gr_mem[ndx], gr->gr_mem[ndx]) + 1;
 482                 }
 483                 gs->gr.gr_mem[ndx] = NULL;
 484         }
 485
 486         return (&gs->gr);
 487 }
 488
 489 /*
 490  * Scan a line and place it into a group structure.
 491  */
 492 static bool
 493 __gr_scan(char *line, struct group *gr)
 494 {
 495         char *loc;
 496         int ndx;
 497
 498         /* Assign non-member information to structure. */
 499         gr->gr_name = line;
 500         if ((loc = strchr(line, ':')) == NULL)
 501                 return (false);
 502         *loc = '\0';
 503         gr->gr_passwd = loc + 1;
 504         if (*gr->gr_passwd == ':')
 505                 *gr->gr_passwd = '\0';
 506         else {
 507                 if ((loc = strchr(loc + 1, ':')) == NULL)
 508                         return (false);
 509                 *loc = '\0';
 510         }
 511         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 512                 return (false);
 513
 514         /* Assign member information to structure. */
 515         if ((loc = strchr(loc + 1, ':')) == NULL)
 516                 return (false);
 517         line = loc + 1;
 518         gr->gr_mem = NULL;
 519         ndx = 0;
 520         do {
 521                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 522                     (ndx + 1));
 523                 if (gr->gr_mem == NULL)
 524                         return (false);
 525
 526                 /* Skip locations without members (i.e., empty string). */
 527                 do {
 528                         gr->gr_mem[ndx] = strsep(&line, ",");
 529                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 530         } while (gr->gr_mem[ndx++] != NULL);
 531
 532         return (true);
 533 }
 534
 535 /*
 536  * Create a struct group from a line.
 537  */
 538 struct group *
 539 gr_scan(const char *line)
 540 {
 541         struct group gr;
 542         char *line_copy;
 543         struct group *new_gr;
 544
 545         if ((line_copy = strdup(line)) == NULL)
 546                 return (NULL);
 547         if (!__gr_scan(line_copy, &gr)) {
 548                 free(line_copy);
 549                 return (NULL);
 550         }
 551         new_gr = gr_dup(&gr);
 552         free(line_copy);
 553         if (gr.gr_mem != NULL)
 554                 free(gr.gr_mem);
 555
 556         return (new_gr);
 557 }