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 = flopen(group_file, O_RDONLY|O_NONBLOCK, 0);
 110                 if (lockfd == -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         if (chmod(tempname, 0644) != 0)
 320                 return (-1);
 321
 322         return (rename(tempname, group_file));
 323 }
 324
 325 /*
 326  * Clean up. Preserver errno for the caller's convenience.
 327  */
 328 void
 329 gr_fini(void)
 330 {
 331         int serrno;
 332
 333         if (!initialized)
 334                 return;
 335         initialized = 0;
 336         serrno = errno;
 337         if (*tempname != '\0') {
 338                 unlink(tempname);
 339                 *tempname = '\0';
 340         }
 341         if (lockfd != -1)
 342                 close(lockfd);
 343         errno = serrno;
 344 }
 345
 346 /*
 347  * Compares two struct group's.
 348  */
 349 int
 350 gr_equal(const struct group *gr1, const struct group *gr2)
 351 {
 352         int gr1_ndx;
 353         int gr2_ndx;
 354         bool found;
 355
 356         /* Check that the non-member information is the same. */
 357         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 358                 if (gr1->gr_name != gr2->gr_name)
 359                         return (false);
 360         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 361                 return (false);
 362         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 363                 if (gr1->gr_passwd != gr2->gr_passwd)
 364                         return (false);
 365         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 366                 return (false);
 367         if (gr1->gr_gid != gr2->gr_gid)
 368                 return (false);
 369
 370         /* Check all members in both groups. */
 371         if (gr1->gr_mem == NULL || gr2->gr_mem == NULL) {
 372                 if (gr1->gr_mem != gr2->gr_mem)
 373                         return (false);
 374         } else {
 375                 for (found = false, gr1_ndx = 0; gr1->gr_mem[gr1_ndx] != NULL;
 376                     gr1_ndx++) {
 377                         for (gr2_ndx = 0; gr2->gr_mem[gr2_ndx] != NULL;
 378                             gr2_ndx++)
 379                                 if (strcmp(gr1->gr_mem[gr1_ndx],
 380                                     gr2->gr_mem[gr2_ndx]) == 0) {
 381                                         found = true;
 382                                         break;
 383                                 }
 384                         if (!found)
 385                                 return (false);
 386                 }
 387
 388                 /* Check that group2 does not have more members than group1. */
 389                 if (gr2->gr_mem[gr1_ndx] != NULL)
 390                         return (false);
 391         }
 392
 393         return (true);
 394 }
 395
 396 /*
 397  * Make a group line out of a struct group.
 398  */
 399 char *
 400 gr_make(const struct group *gr)
 401 {
 402         char *line;
 403         size_t line_size;
 404         int ndx;
 405
 406         /* Calculate the length of the group line. */
 407         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 408             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 409         if (gr->gr_mem != NULL) {
 410                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 411                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 412                 if (ndx > 0)
 413                         line_size--;
 414         }
 415
 416         /* Create the group line and fill it. */
 417         if ((line = malloc(line_size)) == NULL)
 418                 return (NULL);
 419         snprintf(line, line_size, group_line_format, gr->gr_name, gr->gr_passwd,
 420             (uintmax_t)gr->gr_gid);
 421         if (gr->gr_mem != NULL)
 422                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 423                         strcat(line, gr->gr_mem[ndx]);
 424                         if (gr->gr_mem[ndx + 1] != NULL)
 425                                 strcat(line, ",");
 426                 }
 427
 428         return (line);
 429 }
 430
 431 /*
 432  * Duplicate a struct group.
 433  */
 434 struct group *
 435 gr_dup(const struct group *gr)
 436 {
 437         char *dst;
 438         size_t len;
 439         struct group_storage *gs;
 440         int ndx;
 441         int num_mem;
 442
 443         /* Calculate size of the group. */
 444         len = sizeof(*gs);
 445         if (gr->gr_name != NULL)
 446                 len += strlen(gr->gr_name) + 1;
 447         if (gr->gr_passwd != NULL)
 448                 len += strlen(gr->gr_passwd) + 1;
 449         if (gr->gr_mem != NULL) {
 450                 for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++)
 451                         len += strlen(gr->gr_mem[num_mem]) + 1;
 452                 len += (num_mem + 1) * sizeof(*gr->gr_mem);
 453         } else
 454                 num_mem = -1;
 455
 456         /* Create new group and copy old group into it. */
 457         if ((gs = calloc(1, len)) == NULL)
 458                 return (NULL);
 459         dst = (char *)&gs->members[num_mem + 1];
 460         if (gr->gr_name != NULL) {
 461                 gs->gr.gr_name = dst;
 462                 dst = stpcpy(gs->gr.gr_name, gr->gr_name) + 1;
 463         }
 464         if (gr->gr_passwd != NULL) {
 465                 gs->gr.gr_passwd = dst;
 466                 dst = stpcpy(gs->gr.gr_passwd, gr->gr_passwd) + 1;
 467         }
 468         gs->gr.gr_gid = gr->gr_gid;
 469         if (gr->gr_mem != NULL) {
 470                 gs->gr.gr_mem = gs->members;
 471                 for (ndx = 0; ndx < num_mem; ndx++) {
 472                         gs->gr.gr_mem[ndx] = dst;
 473                         dst = stpcpy(gs->gr.gr_mem[ndx], gr->gr_mem[ndx]) + 1;
 474                 }
 475                 gs->gr.gr_mem[ndx] = NULL;
 476         }
 477
 478         return (&gs->gr);
 479 }
 480
 481 /*
 482  * Scan a line and place it into a group structure.
 483  */
 484 static bool
 485 __gr_scan(char *line, struct group *gr)
 486 {
 487         char *loc;
 488         int ndx;
 489
 490         /* Assign non-member information to structure. */
 491         gr->gr_name = line;
 492         if ((loc = strchr(line, ':')) == NULL)
 493                 return (false);
 494         *loc = '\0';
 495         gr->gr_passwd = loc + 1;
 496         if (*gr->gr_passwd == ':')
 497                 *gr->gr_passwd = '\0';
 498         else {
 499                 if ((loc = strchr(loc + 1, ':')) == NULL)
 500                         return (false);
 501                 *loc = '\0';
 502         }
 503         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 504                 return (false);
 505
 506         /* Assign member information to structure. */
 507         if ((loc = strchr(loc + 1, ':')) == NULL)
 508                 return (false);
 509         line = loc + 1;
 510         gr->gr_mem = NULL;
 511         ndx = 0;
 512         do {
 513                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 514                     (ndx + 1));
 515                 if (gr->gr_mem == NULL)
 516                         return (false);
 517
 518                 /* Skip locations without members (i.e., empty string). */
 519                 do {
 520                         gr->gr_mem[ndx] = strsep(&line, ",");
 521                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 522         } while (gr->gr_mem[ndx++] != NULL);
 523
 524         return (true);
 525 }
 526
 527 /*
 528  * Create a struct group from a line.
 529  */
 530 struct group *
 531 gr_scan(const char *line)
 532 {
 533         struct group gr;
 534         char *line_copy;
 535         struct group *new_gr;
 536
 537         if ((line_copy = strdup(line)) == NULL)
 538                 return (NULL);
 539         if (!__gr_scan(line_copy, &gr)) {
 540                 free(line_copy);
 541                 return (NULL);
 542         }
 543         new_gr = gr_dup(&gr);
 544         free(line_copy);
 545         if (gr.gr_mem != NULL)
 546                 free(gr.gr_mem);
 547
 548         return (new_gr);
 549 }