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