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 static int lockfd = -1;
  48 static char group_dir[PATH_MAX];
  49 static char group_file[PATH_MAX];
  50 static char tempname[PATH_MAX];
  51 static int initialized;
  52
  53 /*
  54  * Initialize statics
  55  */
  56 int
  57 gr_init(const char *dir, const char *group)
  58 {
  59
  60         if (dir == NULL) {
  61                 strcpy(group_dir, _PATH_ETC);
  62         } else {
  63                 if (strlen(dir) >= sizeof(group_dir)) {
  64                         errno = ENAMETOOLONG;
  65                         return (-1);
  66                 }
  67                 strcpy(group_dir, dir);
  68         }
  69
  70         if (group == NULL) {
  71                 if (dir == NULL) {
  72                         strcpy(group_file, _PATH_GROUP);
  73                 } else if (snprintf(group_file, sizeof(group_file), "%s/group",
  74                         group_dir) > (int)sizeof(group_file)) {
  75                         errno = ENAMETOOLONG;
  76                         return (-1);
  77                 }
  78         } else {
  79                 if (strlen(group) >= sizeof(group_file)) {
  80                         errno = ENAMETOOLONG;
  81                         return (-1);
  82                 }
  83                 strcpy(group_file, group);
  84         }
  85
  86         initialized = 1;
  87         return (0);
  88 }
  89
  90 /*
  91  * Lock the group file
  92  */
  93 int
  94 gr_lock(void)
  95 {
  96         if (*group_file == '\0')
  97                 return (-1);
  98
  99         for (;;) {
 100                 struct stat st;
 101
 102                 lockfd = flopen(group_file, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 103                 if (lockfd == -1) {
 104                         if (errno == EWOULDBLOCK) {
 105                                 errx(1, "the group file is busy");
 106                         } else {
 107                                 err(1, "could not lock the group file: ");
 108                         }
 109                 }
 110                 if (fstat(lockfd, &st) == -1)
 111                         err(1, "fstat() failed: ");
 112                 if (st.st_nlink != 0)
 113                         break;
 114                 close(lockfd);
 115                 lockfd = -1;
 116         }
 117         return (lockfd);
 118 }
 119
 120 /*
 121  * Create and open a presmuably safe temp file for editing group data
 122  */
 123 int
 124 gr_tmp(int mfd)
 125 {
 126         char buf[8192];
 127         ssize_t nr;
 128         const char *p;
 129         int tfd;
 130
 131         if (*group_file == '\0')
 132                 return (-1);
 133         if ((p = strrchr(group_file, '/')))
 134                 ++p;
 135         else
 136                 p = group_file;
 137         if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
 138                 (int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
 139                 errno = ENAMETOOLONG;
 140                 return (-1);
 141         }
 142         if ((tfd = mkstemp(tempname)) == -1)
 143                 return (-1);
 144         if (mfd != -1) {
 145                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 146                         if (write(tfd, buf, (size_t)nr) != nr)
 147                                 break;
 148                 if (nr != 0) {
 149                         unlink(tempname);
 150                         *tempname = '\0';
 151                         close(tfd);
 152                         return (-1);
 153                 }
 154         }
 155         return (tfd);
 156 }
 157
 158 /*
 159  * Copy the group file from one descriptor to another, replacing, deleting
 160  * or adding a single record on the way.
 161  */
 162 int
 163 gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
 164 {
 165         char buf[8192], *end, *line, *p, *q, *r, t;
 166         struct group *fgr;
 167         const struct group *sgr;
 168         size_t len;
 169         int eof, readlen;
 170
 171         sgr = gr;
 172         if (gr == NULL) {
 173                 line = NULL;
 174                 if (old_gr == NULL)
 175                         return (-1);
 176                 sgr = old_gr;
 177         } else if ((line = gr_make(gr)) == NULL)
 178                 return (-1);
 179
 180         eof = 0;
 181         len = 0;
 182         p = q = end = buf;
 183         for (;;) {
 184                 /* find the end of the current line */
 185                 for (p = q; q < end && *q != '\0'; ++q)
 186                         if (*q == '\n')
 187                                 break;
 188
 189                 /* if we don't have a complete line, fill up the buffer */
 190                 if (q >= end) {
 191                         if (eof)
 192                                 break;
 193                         if ((size_t)(q - p) >= sizeof(buf)) {
 194                                 warnx("group line too long");
 195                                 errno = EINVAL; /* hack */
 196                                 goto err;
 197                         }
 198                         if (p < end) {
 199                                 q = memmove(buf, p, end -p);
 200                                 end -= p - buf;
 201                         } else {
 202                                 p = q = end = buf;
 203                         }
 204                         readlen = read(ffd, end, sizeof(buf) - (end -buf));
 205                         if (readlen == -1)
 206                                 goto err;
 207                         else
 208                                 len = (size_t)readlen;
 209                         if (len == 0 && p == buf)
 210                                 break;
 211                         end += len;
 212                         len = end - buf;
 213                         if (len < (ssize_t)sizeof(buf)) {
 214                                 eof = 1;
 215                                 if (len > 0 && buf[len -1] != '\n')
 216                                         ++len, *end++ = '\n';
 217                         }
 218                         continue;
 219                 }
 220
 221                 /* is it a blank line or a comment? */
 222                 for (r = p; r < q && isspace(*r); ++r)
 223                         /* nothing */;
 224                 if (r == q || *r == '#') {
 225                         /* yep */
 226                         if (write(tfd, p, q -p + 1) != q - p + 1)
 227                                 goto err;
 228                         ++q;
 229                         continue;
 230                 }
 231
 232                 /* is it the one we're looking for? */
 233
 234                 t = *q;
 235                 *q = '\0';
 236
 237                 fgr = gr_scan(r);
 238
 239                 /* fgr is either a struct group for the current line,
 240                  * or NULL if the line is malformed.
 241                  */
 242
 243                 *q = t;
 244                 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
 245                         /* nope */
 246                         if (fgr != NULL)
 247                                 free(fgr);
 248                         if (write(tfd, p, q - p + 1) != q - p + 1)
 249                                 goto err;
 250                         ++q;
 251                         continue;
 252                 }
 253                 if (old_gr && !gr_equal(fgr, old_gr)) {
 254                         warnx("entry inconsistent");
 255                         free(fgr);
 256                         errno = EINVAL; /* hack */
 257                         goto err;
 258                 }
 259                 free(fgr);
 260
 261                 /* it is, replace or remove it */
 262                 if (line != NULL) {
 263                         len = strlen(line);
 264                         if (write(tfd, line, len) != (int) len)
 265                                 goto err;
 266                 } else {
 267                         /* when removed, avoid the \n */
 268                         q++;
 269                 }
 270                 /* we're done, just copy the rest over */
 271                 for (;;) {
 272                         if (write(tfd, q, end - q) != end - q)
 273                                 goto err;
 274                         q = buf;
 275                         readlen = read(ffd, buf, sizeof(buf));
 276                         if (readlen == 0)
 277                                 break;
 278                         else
 279                                 len = (size_t)readlen;
 280                         if (readlen == -1)
 281                                 goto err;
 282                         end = buf + len;
 283                 }
 284                 goto done;
 285         }
 286
 287         /* if we got here, we didn't find the old entry */
 288         if (line == NULL) {
 289                 errno = ENOENT;
 290                 goto err;
 291         }
 292         len = strlen(line);
 293         if ((size_t)write(tfd, line, len) != len ||
 294            write(tfd, "\n", 1) != 1)
 295                 goto err;
 296  done:
 297         if (line != NULL)
 298                 free(line);
 299         return (0);
 300  err:
 301         if (line != NULL)
 302                 free(line);
 303         return (-1);
 304 }
 305
 306 /*
 307  * Regenerate the group file
 308  */
 309 int
 310 gr_mkdb(void)
 311 {
 312         if (chmod(tempname, 0644) != 0)
 313                 return (-1);
 314
 315         return (rename(tempname, group_file));
 316 }
 317
 318 /*
 319  * Clean up. Preserver errno for the caller's convenience.
 320  */
 321 void
 322 gr_fini(void)
 323 {
 324         int serrno;
 325
 326         if (!initialized)
 327                 return;
 328         initialized = 0;
 329         serrno = errno;
 330         if (*tempname != '\0') {
 331                 unlink(tempname);
 332                 *tempname = '\0';
 333         }
 334         if (lockfd != -1)
 335                 close(lockfd);
 336         errno = serrno;
 337 }
 338
 339 /*
 340  * Compares two struct group's.
 341  */
 342 int
 343 gr_equal(const struct group *gr1, const struct group *gr2)
 344 {
 345         int gr1_ndx;
 346         int gr2_ndx;
 347
 348         /* Check that the non-member information is the same. */
 349         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 350                 if (gr1->gr_name != gr2->gr_name)
 351                         return (false);
 352         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 353                 return (false);
 354         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 355                 if (gr1->gr_passwd != gr2->gr_passwd)
 356                         return (false);
 357         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 358                 return (false);
 359         if (gr1->gr_gid != gr2->gr_gid)
 360                 return (false);
 361
 362         /* Check all members in both groups. */
 363         if (gr1->gr_mem == NULL || gr2->gr_mem == NULL) {
 364                 if (gr1->gr_mem != gr2->gr_mem)
 365                         return (false);
 366         } else {
 367                 for (gr1_ndx = 0; gr1->gr_mem[gr1_ndx] != NULL; gr1_ndx++) {
 368                         for (gr2_ndx = 0;; gr2_ndx++) {
 369                                 if (gr2->gr_mem[gr2_ndx] == NULL)
 370                                         return (false);
 371                                 if (strcmp(gr1->gr_mem[gr1_ndx],
 372                                     gr2->gr_mem[gr2_ndx]) == 0) {
 373                                         break;
 374                                 }
 375                         }
 376                 }
 377
 378                 /* Check that group2 does not have more members than group1. */
 379                 if (gr2->gr_mem[gr1_ndx] != NULL)
 380                         return (false);
 381         }
 382
 383         return (true);
 384 }
 385
 386 /*
 387  * Make a group line out of a struct group.
 388  */
 389 char *
 390 gr_make(const struct group *gr)
 391 {
 392         const char *group_line_format = "%s:%s:%ju:";
 393         char *line;
 394         size_t line_size;
 395         int ndx;
 396
 397         /* Calculate the length of the group line. */
 398         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 399             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 400         if (gr->gr_mem != NULL) {
 401                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 402                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 403                 if (ndx > 0)
 404                         line_size--;
 405         }
 406
 407         /* Create the group line and fill it. */
 408         if ((line = malloc(line_size)) == NULL)
 409                 return (NULL);
 410         snprintf(line, line_size, group_line_format, gr->gr_name, gr->gr_passwd,
 411             (uintmax_t)gr->gr_gid);
 412         if (gr->gr_mem != NULL)
 413                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 414                         strcat(line, gr->gr_mem[ndx]);
 415                         if (gr->gr_mem[ndx + 1] != NULL)
 416                                 strcat(line, ",");
 417                 }
 418
 419         return (line);
 420 }
 421
 422 /*
 423  * Duplicate a struct group.
 424  */
 425 struct group *
 426 gr_dup(const struct group *gr)
 427 {
 428         struct group *newgr;
 429         char *dst;
 430         size_t len;
 431         int ndx;
 432         int num_mem;
 433
 434         /* Calculate size of the group. */
 435         len = sizeof(*newgr);
 436         if (gr->gr_name != NULL)
 437                 len += strlen(gr->gr_name) + 1;
 438         if (gr->gr_passwd != NULL)
 439                 len += strlen(gr->gr_passwd) + 1;
 440         if (gr->gr_mem != NULL) {
 441                 for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++)
 442                         len += strlen(gr->gr_mem[num_mem]) + 1;
 443                 len += (num_mem + 1) * sizeof(*gr->gr_mem);
 444         } else
 445                 num_mem = -1;
 446         /* Create new group and copy old group into it. */
 447         if ((newgr = malloc(len)) == NULL)
 448                 return (NULL);
 449         /* point new gr_mem to end of struct + 1 */
 450         if (gr->gr_mem != NULL)
 451                 newgr->gr_mem = (char **)(newgr + 1);
 452         else
 453                 newgr->gr_mem = NULL;
 454         /* point dst after the end of all the gr_mem pointers in newgr */
 455         dst = (char *)&newgr->gr_mem[num_mem + 1];
 456         if (gr->gr_name != NULL) {
 457                 newgr->gr_name = dst;
 458                 dst = stpcpy(dst, gr->gr_name) + 1;
 459         } else {
 460                 newgr->gr_name = NULL;
 461         }
 462         if (gr->gr_passwd != NULL) {
 463                 newgr->gr_passwd = dst;
 464                 dst = stpcpy(dst, gr->gr_passwd) + 1;
 465         } else {
 466                 newgr->gr_passwd = NULL;
 467         }
 468         newgr->gr_gid = gr->gr_gid;
 469         if (gr->gr_mem != NULL) {
 470                 for (ndx = 0; ndx < num_mem; ndx++) {
 471                         newgr->gr_mem[ndx] = dst;
 472                         dst = stpcpy(dst, gr->gr_mem[ndx]) + 1;
 473                 }
 474                 newgr->gr_mem[ndx] = NULL;
 475         }
 476         return (newgr);
 477 }
 478
 479 /*
 480  * Add a new member name to a struct group.
 481  */
 482 struct group *
 483 gr_add(struct group *gr, char *newmember)
 484 {
 485         size_t mlen;
 486         int num_mem=0;
 487         char **members;
 488         struct group *newgr;
 489
 490         if (newmember == NULL)
 491                 return(gr_dup(gr));
 492
 493         if (gr->gr_mem != NULL) {
 494                 for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++) {
 495                         if (strcmp(gr->gr_mem[num_mem], newmember) == 0) {
 496                                 errno = EEXIST;
 497                                 return (NULL);
 498                         }
 499                 }
 500         }
 501         /* Allocate enough for current pointers + 1 more and NULL marker */
 502         mlen = (num_mem + 2) * sizeof(*gr->gr_mem);
 503         if ((members = malloc(mlen)) == NULL)
 504                 return (NULL);
 505         memcpy(members, gr->gr_mem, num_mem * sizeof(*gr->gr_mem));
 506         members[num_mem++] = newmember;
 507         members[num_mem] = NULL;
 508         gr->gr_mem = members;
 509         newgr = gr_dup(gr);
 510         free(members);
 511         return (newgr);
 512 }
 513
 514 /*
 515  * Scan a line and place it into a group structure.
 516  */
 517 static bool
 518 __gr_scan(char *line, struct group *gr)
 519 {
 520         char *loc;
 521         int ndx;
 522
 523         /* Assign non-member information to structure. */
 524         gr->gr_name = line;
 525         if ((loc = strchr(line, ':')) == NULL)
 526                 return (false);
 527         *loc = '\0';
 528         gr->gr_passwd = loc + 1;
 529         if (*gr->gr_passwd == ':')
 530                 *gr->gr_passwd = '\0';
 531         else {
 532                 if ((loc = strchr(loc + 1, ':')) == NULL)
 533                         return (false);
 534                 *loc = '\0';
 535         }
 536         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 537                 return (false);
 538
 539         /* Assign member information to structure. */
 540         if ((loc = strchr(loc + 1, ':')) == NULL)
 541                 return (false);
 542         line = loc + 1;
 543         gr->gr_mem = NULL;
 544         ndx = 0;
 545         do {
 546                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 547                     (ndx + 1));
 548                 if (gr->gr_mem == NULL)
 549                         return (false);
 550
 551                 /* Skip locations without members (i.e., empty string). */
 552                 do {
 553                         gr->gr_mem[ndx] = strsep(&line, ",");
 554                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 555         } while (gr->gr_mem[ndx++] != NULL);
 556
 557         return (true);
 558 }
 559
 560 /*
 561  * Create a struct group from a line.
 562  */
 563 struct group *
 564 gr_scan(const char *line)
 565 {
 566         struct group gr;
 567         char *line_copy;
 568         struct group *new_gr;
 569
 570         if ((line_copy = strdup(line)) == NULL)
 571                 return (NULL);
 572         if (!__gr_scan(line_copy, &gr)) {
 573                 free(line_copy);
 574                 return (NULL);
 575         }
 576         new_gr = gr_dup(&gr);
 577         free(line_copy);
 578         if (gr.gr_mem != NULL)
 579                 free(gr.gr_mem);
 580
 581         return (new_gr);
 582 }