libutil/gr_util.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2008 Sean C. Farley <scf@FreeBSD.org>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer,
  12  *    without modification, immediately at the beginning of the file.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/errno.h>
  34 #include <sys/stat.h>
  35
  36 #include <ctype.h>
  37 #include <err.h>
  38 #include <fcntl.h>
  39 #include <grp.h>
  40 #include <inttypes.h>
  41 #include <libutil.h>
  42 #include <paths.h>
  43 #include <stdbool.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47 #include <unistd.h>
  48
  49 static int lockfd = -1;
  50 static char group_dir[PATH_MAX];
  51 static char group_file[PATH_MAX];
  52 static char tempname[PATH_MAX];
  53 static int initialized;
  54 static size_t grmemlen(const struct group *, const char *, int *);
  55 static struct group *grcopy(const struct group *gr, char *mem, const char *, int ndx);
  56
  57 /*
  58  * Initialize statics
  59  */
  60 int
  61 gr_init(const char *dir, const char *group)
  62 {
  63
  64         if (dir == NULL) {
  65                 strcpy(group_dir, _PATH_ETC);
  66         } else {
  67                 if (strlen(dir) >= sizeof(group_dir)) {
  68                         errno = ENAMETOOLONG;
  69                         return (-1);
  70                 }
  71                 strcpy(group_dir, dir);
  72         }
  73
  74         if (group == NULL) {
  75                 if (dir == NULL) {
  76                         strcpy(group_file, _PATH_GROUP);
  77                 } else if (snprintf(group_file, sizeof(group_file), "%s/group",
  78                         group_dir) > (int)sizeof(group_file)) {
  79                         errno = ENAMETOOLONG;
  80                         return (-1);
  81                 }
  82         } else {
  83                 if (strlen(group) >= sizeof(group_file)) {
  84                         errno = ENAMETOOLONG;
  85                         return (-1);
  86                 }
  87                 strcpy(group_file, group);
  88         }
  89
  90         initialized = 1;
  91         return (0);
  92 }
  93
  94 /*
  95  * Lock the group file
  96  */
  97 int
  98 gr_lock(void)
  99 {
 100         if (*group_file == '\0')
 101                 return (-1);
 102
 103         for (;;) {
 104                 struct stat st;
 105
 106                 lockfd = flopen(group_file, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 107                 if (lockfd == -1) {
 108                         if (errno == EWOULDBLOCK) {
 109                                 errx(1, "the group file is busy");
 110                         } else {
 111                                 err(1, "could not lock the group file: ");
 112                         }
 113                 }
 114                 if (fstat(lockfd, &st) == -1)
 115                         err(1, "fstat() failed: ");
 116                 if (st.st_nlink != 0)
 117                         break;
 118                 close(lockfd);
 119                 lockfd = -1;
 120         }
 121         return (lockfd);
 122 }
 123
 124 /*
 125  * Create and open a presmuably safe temp file for editing group data
 126  */
 127 int
 128 gr_tmp(int mfd)
 129 {
 130         char buf[8192];
 131         ssize_t nr;
 132         const char *p;
 133         int tfd;
 134
 135         if (*group_file == '\0')
 136                 return (-1);
 137         if ((p = strrchr(group_file, '/')))
 138                 ++p;
 139         else
 140                 p = group_file;
 141         if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
 142                 (int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
 143                 errno = ENAMETOOLONG;
 144                 return (-1);
 145         }
 146         if ((tfd = mkostemp(tempname, 0)) == -1)
 147                 return (-1);
 148         if (mfd != -1) {
 149                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 150                         if (write(tfd, buf, (size_t)nr) != nr)
 151                                 break;
 152                 if (nr != 0) {
 153                         unlink(tempname);
 154                         *tempname = '\0';
 155                         close(tfd);
 156                         return (-1);
 157                 }
 158         }
 159         return (tfd);
 160 }
 161
 162 /*
 163  * Copy the group file from one descriptor to another, replacing, deleting
 164  * or adding a single record on the way.
 165  */
 166 int
 167 gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
 168 {
 169         char *buf, *end, *line, *p, *q, *r, *tmp;
 170         struct group *fgr;
 171         const struct group *sgr;
 172         size_t len, size;
 173         int eof, readlen;
 174         char t;
 175
 176         if (old_gr == NULL && gr == NULL)
 177                 return(-1);
 178
 179         sgr = old_gr;
 180         /* deleting a group */
 181         if (gr == NULL) {
 182                 line = NULL;
 183         } else {
 184                 if ((line = gr_make(gr)) == NULL)
 185                         return (-1);
 186         }
 187
 188         /* adding a group */
 189         if (sgr == NULL)
 190                 sgr = gr;
 191
 192         /* initialize the buffer */
 193         if ((buf = malloc(size = 1024)) == NULL)
 194                 goto err;
 195
 196         eof = 0;
 197         len = 0;
 198         p = q = end = buf;
 199         for (;;) {
 200                 /* find the end of the current line */
 201                 for (p = q; q < end && *q != '\0'; ++q)
 202                         if (*q == '\n')
 203                                 break;
 204
 205                 /* if we don't have a complete line, fill up the buffer */
 206                 if (q >= end) {
 207                         if (eof)
 208                                 break;
 209                         while ((size_t)(q - p) >= size) {
 210                                 if ((tmp = reallocarray(buf, 2, size)) == NULL) {
 211                                         warnx("group line too long");
 212                                         goto err;
 213                                 }
 214                                 p = tmp + (p - buf);
 215                                 q = tmp + (q - buf);
 216                                 end = tmp + (end - buf);
 217                                 buf = tmp;
 218                                 size = size * 2;
 219                         }
 220                         if (p < end) {
 221                                 q = memmove(buf, p, end -p);
 222                                 end -= p - buf;
 223                         } else {
 224                                 p = q = end = buf;
 225                         }
 226                         readlen = read(ffd, end, size - (end - buf));
 227                         if (readlen == -1)
 228                                 goto err;
 229                         else
 230                                 len = (size_t)readlen;
 231                         if (len == 0 && p == buf)
 232                                 break;
 233                         end += len;
 234                         len = end - buf;
 235                         if (len < size) {
 236                                 eof = 1;
 237                                 if (len > 0 && buf[len -1] != '\n')
 238                                         ++len, *end++ = '\n';
 239                         }
 240                         continue;
 241                 }
 242
 243                 /* is it a blank line or a comment? */
 244                 for (r = p; r < q && isspace(*r); ++r)
 245                         /* nothing */;
 246                 if (r == q || *r == '#') {
 247                         /* yep */
 248                         if (write(tfd, p, q -p + 1) != q - p + 1)
 249                                 goto err;
 250                         ++q;
 251                         continue;
 252                 }
 253
 254                 /* is it the one we're looking for? */
 255
 256                 t = *q;
 257                 *q = '\0';
 258
 259                 fgr = gr_scan(r);
 260
 261                 /* fgr is either a struct group for the current line,
 262                  * or NULL if the line is malformed.
 263                  */
 264
 265                 *q = t;
 266                 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
 267                         /* nope */
 268                         if (fgr != NULL)
 269                                 free(fgr);
 270                         if (write(tfd, p, q - p + 1) != q - p + 1)
 271                                 goto err;
 272                         ++q;
 273                         continue;
 274                 }
 275                 if (old_gr && !gr_equal(fgr, old_gr)) {
 276                         warnx("entry inconsistent");
 277                         free(fgr);
 278                         errno = EINVAL; /* hack */
 279                         goto err;
 280                 }
 281                 free(fgr);
 282
 283                 /* it is, replace or remove it */
 284                 if (line != NULL) {
 285                         len = strlen(line);
 286                         if (write(tfd, line, len) != (int) len)
 287                                 goto err;
 288                 } else {
 289                         /* when removed, avoid the \n */
 290                         q++;
 291                 }
 292                 /* we're done, just copy the rest over */
 293                 for (;;) {
 294                         if (write(tfd, q, end - q) != end - q)
 295                                 goto err;
 296                         q = buf;
 297                         readlen = read(ffd, buf, size);
 298                         if (readlen == 0)
 299                                 break;
 300                         else
 301                                 len = (size_t)readlen;
 302                         if (readlen == -1)
 303                                 goto err;
 304                         end = buf + len;
 305                 }
 306                 goto done;
 307         }
 308
 309         /* if we got here, we didn't find the old entry */
 310         if (line == NULL) {
 311                 errno = ENOENT;
 312                 goto err;
 313         }
 314         len = strlen(line);
 315         if ((size_t)write(tfd, line, len) != len ||
 316            write(tfd, "\n", 1) != 1)
 317                 goto err;
 318  done:
 319         free(line);
 320         free(buf);
 321         return (0);
 322  err:
 323         free(line);
 324         free(buf);
 325         return (-1);
 326 }
 327
 328 /*
 329  * Regenerate the group file
 330  */
 331 int
 332 gr_mkdb(void)
 333 {
 334         int fd;
 335
 336         if (chmod(tempname, 0644) != 0)
 337                 return (-1);
 338
 339         if (rename(tempname, group_file) != 0)
 340                 return (-1);
 341
 342         /*
 343          * Make sure new group file is safe on disk. To improve performance we
 344          * will call fsync() to the directory where file lies
 345          */
 346         if ((fd = open(group_dir, O_RDONLY|O_DIRECTORY)) == -1)
 347                 return (-1);
 348
 349         if (fsync(fd) != 0) {
 350                 close(fd);
 351                 return (-1);
 352         }
 353
 354         close(fd);
 355         return(0);
 356 }
 357
 358 /*
 359  * Clean up. Preserves errno for the caller's convenience.
 360  */
 361 void
 362 gr_fini(void)
 363 {
 364         int serrno;
 365
 366         if (!initialized)
 367                 return;
 368         initialized = 0;
 369         serrno = errno;
 370         if (*tempname != '\0') {
 371                 unlink(tempname);
 372                 *tempname = '\0';
 373         }
 374         if (lockfd != -1)
 375                 close(lockfd);
 376         errno = serrno;
 377 }
 378
 379 /*
 380  * Compares two struct group's.
 381  */
 382 int
 383 gr_equal(const struct group *gr1, const struct group *gr2)
 384 {
 385
 386         /* Check that the non-member information is the same. */
 387         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 388                 if (gr1->gr_name != gr2->gr_name)
 389                         return (false);
 390         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 391                 return (false);
 392         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 393                 if (gr1->gr_passwd != gr2->gr_passwd)
 394                         return (false);
 395         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 396                 return (false);
 397         if (gr1->gr_gid != gr2->gr_gid)
 398                 return (false);
 399
 400         /*
 401          * Check all members in both groups.
 402          * getgrnam can return gr_mem with a pointer to NULL.
 403          * gr_dup and gr_add strip out this superfluous NULL, setting
 404          * gr_mem to NULL for no members.
 405         */
 406         if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
 407                 int i;
 408
 409                 for (i = 0;
 410                     gr1->gr_mem[i] != NULL && gr2->gr_mem[i] != NULL; i++) {
 411                         if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
 412                                 return (false);
 413                 }
 414                 if (gr1->gr_mem[i] != NULL || gr2->gr_mem[i] != NULL)
 415                         return (false);
 416         } else if (gr1->gr_mem != NULL && gr1->gr_mem[0] != NULL) {
 417                 return (false);
 418         } else if (gr2->gr_mem != NULL && gr2->gr_mem[0] != NULL) {
 419                 return (false);
 420         }
 421
 422         return (true);
 423 }
 424
 425 /*
 426  * Make a group line out of a struct group.
 427  */
 428 char *
 429 gr_make(const struct group *gr)
 430 {
 431         const char *group_line_format = "%s:%s:%ju:";
 432         const char *sep;
 433         char *line;
 434         char *p;
 435         size_t line_size;
 436         int ndx;
 437
 438         /* Calculate the length of the group line. */
 439         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 440             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 441         if (gr->gr_mem != NULL) {
 442                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 443                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 444                 if (ndx > 0)
 445                         line_size--;
 446         }
 447
 448         /* Create the group line and fill it. */
 449         if ((line = p = malloc(line_size)) == NULL)
 450                 return (NULL);
 451         p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
 452             (uintmax_t)gr->gr_gid);
 453         if (gr->gr_mem != NULL) {
 454                 sep = "";
 455                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 456                         p = stpcpy(p, sep);
 457                         p = stpcpy(p, gr->gr_mem[ndx]);
 458                         sep = ",";
 459                 }
 460         }
 461
 462         return (line);
 463 }
 464
 465 /*
 466  * Duplicate a struct group.
 467  */
 468 struct group *
 469 gr_dup(const struct group *gr)
 470 {
 471         return (gr_add(gr, NULL));
 472 }
 473 /*
 474  * Add a new member name to a struct group.
 475  */
 476 struct group *
 477 gr_add(const struct group *gr, const char *newmember)
 478 {
 479         char *mem;
 480         size_t len;
 481         int num_mem;
 482
 483         num_mem = 0;
 484         len = grmemlen(gr, newmember, &num_mem);
 485         /* Create new group and copy old group into it. */
 486         if ((mem = malloc(len)) == NULL)
 487                 return (NULL);
 488         return (grcopy(gr, mem, newmember, num_mem));
 489 }
 490
 491 /* It is safer to walk the pointers given at gr_mem since there is no
 492  * guarantee the gr_mem + strings are contiguous in the given struct group
 493  * but compactify the new group into the following form.
 494  *
 495  * The new struct is laid out like this in memory. The example given is
 496  * for a group with two members only.
 497  *
 498  * {
 499  * (char *name)
 500  * (char *passwd)
 501  * (int gid)
 502  * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
 503  * gr_mem area
 504  * (member1 *)
 505  * (member2 *)
 506  * (NULL)
 507  * (name string)
 508  * (passwd string)
 509  * (member1 string)
 510  * (member2 string)
 511  * }
 512  */
 513 /*
 514  * Copy the contents of a group plus given name to a preallocated group struct
 515  */
 516 static struct group *
 517 grcopy(const struct group *gr, char *dst, const char *name, int ndx)
 518 {
 519         int i;
 520         struct group *newgr;
 521
 522         newgr = (struct group *)(void *)dst;    /* avoid alignment warning */
 523         dst += sizeof(*newgr);
 524         if (ndx != 0) {
 525                 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */
 526                 dst += (ndx + 1) * sizeof(*newgr->gr_mem);
 527         } else
 528                 newgr->gr_mem = NULL;
 529         if (gr->gr_name != NULL) {
 530                 newgr->gr_name = dst;
 531                 dst = stpcpy(dst, gr->gr_name) + 1;
 532         } else
 533                 newgr->gr_name = NULL;
 534         if (gr->gr_passwd != NULL) {
 535                 newgr->gr_passwd = dst;
 536                 dst = stpcpy(dst, gr->gr_passwd) + 1;
 537         } else
 538                 newgr->gr_passwd = NULL;
 539         newgr->gr_gid = gr->gr_gid;
 540         i = 0;
 541         /* Original group struct might have a NULL gr_mem */
 542         if (gr->gr_mem != NULL) {
 543                 for (; gr->gr_mem[i] != NULL; i++) {
 544                         newgr->gr_mem[i] = dst;
 545                         dst = stpcpy(dst, gr->gr_mem[i]) + 1;
 546                 }
 547         }
 548         /* If name is not NULL, newgr->gr_mem is known to be not NULL */
 549         if (name != NULL) {
 550                 newgr->gr_mem[i++] = dst;
 551                 dst = stpcpy(dst, name) + 1;
 552         }
 553         /* if newgr->gr_mem is not NULL add NULL marker */
 554         if (newgr->gr_mem != NULL)
 555                 newgr->gr_mem[i] = NULL;
 556
 557         return (newgr);
 558 }
 559
 560 /*
 561  *  Calculate length of a struct group + given name
 562  */
 563 static size_t
 564 grmemlen(const struct group *gr, const char *name, int *num_mem)
 565 {
 566         size_t len;
 567         int i;
 568
 569         if (gr == NULL)
 570                 return (0);
 571         /* Calculate size of the group. */
 572         len = sizeof(*gr);
 573         if (gr->gr_name != NULL)
 574                 len += strlen(gr->gr_name) + 1;
 575         if (gr->gr_passwd != NULL)
 576                 len += strlen(gr->gr_passwd) + 1;
 577         i = 0;
 578         if (gr->gr_mem != NULL) {
 579                 for (; gr->gr_mem[i] != NULL; i++) {
 580                         len += strlen(gr->gr_mem[i]) + 1;
 581                         len += sizeof(*gr->gr_mem);
 582                 }
 583         }
 584         if (name != NULL) {
 585                 i++;
 586                 len += strlen(name) + 1;
 587                 len += sizeof(*gr->gr_mem);
 588         }
 589         /* Allow for NULL pointer */
 590         if (i != 0)
 591                 len += sizeof(*gr->gr_mem);
 592         *num_mem = i;
 593         return(len);
 594 }
 595
 596 /*
 597  * Scan a line and place it into a group structure.
 598  */
 599 static bool
 600 __gr_scan(char *line, struct group *gr)
 601 {
 602         char *loc;
 603         int ndx;
 604
 605         /* Assign non-member information to structure. */
 606         gr->gr_name = line;
 607         if ((loc = strchr(line, ':')) == NULL)
 608                 return (false);
 609         *loc = '\0';
 610         gr->gr_passwd = loc + 1;
 611         if (*gr->gr_passwd == ':')
 612                 *gr->gr_passwd = '\0';
 613         else {
 614                 if ((loc = strchr(loc + 1, ':')) == NULL)
 615                         return (false);
 616                 *loc = '\0';
 617         }
 618         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 619                 return (false);
 620
 621         /* Assign member information to structure. */
 622         if ((loc = strchr(loc + 1, ':')) == NULL)
 623                 return (false);
 624         line = loc + 1;
 625         gr->gr_mem = NULL;
 626         ndx = 0;
 627         do {
 628                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 629                     (ndx + 1));
 630                 if (gr->gr_mem == NULL)
 631                         return (false);
 632
 633                 /* Skip locations without members (i.e., empty string). */
 634                 do {
 635                         gr->gr_mem[ndx] = strsep(&line, ",");
 636                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 637         } while (gr->gr_mem[ndx++] != NULL);
 638
 639         return (true);
 640 }
 641
 642 /*
 643  * Create a struct group from a line.
 644  */
 645 struct group *
 646 gr_scan(const char *line)
 647 {
 648         struct group gr;
 649         char *line_copy;
 650         struct group *new_gr;
 651
 652         if ((line_copy = strdup(line)) == NULL)
 653                 return (NULL);
 654         if (!__gr_scan(line_copy, &gr)) {
 655                 free(line_copy);
 656                 return (NULL);
 657         }
 658         new_gr = gr_dup(&gr);
 659         free(line_copy);
 660         if (gr.gr_mem != NULL)
 661                 free(gr.gr_mem);
 662
 663         return (new_gr);
 664 }