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 static size_t grmemlen(const struct group *, const char *, int *);
  53 static struct group *grcopy(const struct group *gr, char *mem, const char *, int ndx);
  54
  55 /*
  56  * Initialize statics
  57  */
  58 int
  59 gr_init(const char *dir, const char *group)
  60 {
  61
  62         if (dir == NULL) {
  63                 strcpy(group_dir, _PATH_ETC);
  64         } else {
  65                 if (strlen(dir) >= sizeof(group_dir)) {
  66                         errno = ENAMETOOLONG;
  67                         return (-1);
  68                 }
  69                 strcpy(group_dir, dir);
  70         }
  71
  72         if (group == NULL) {
  73                 if (dir == NULL) {
  74                         strcpy(group_file, _PATH_GROUP);
  75                 } else if (snprintf(group_file, sizeof(group_file), "%s/group",
  76                         group_dir) > (int)sizeof(group_file)) {
  77                         errno = ENAMETOOLONG;
  78                         return (-1);
  79                 }
  80         } else {
  81                 if (strlen(group) >= sizeof(group_file)) {
  82                         errno = ENAMETOOLONG;
  83                         return (-1);
  84                 }
  85                 strcpy(group_file, group);
  86         }
  87
  88         initialized = 1;
  89         return (0);
  90 }
  91
  92 /*
  93  * Lock the group file
  94  */
  95 int
  96 gr_lock(void)
  97 {
  98         if (*group_file == '\0')
  99                 return (-1);
 100
 101         for (;;) {
 102                 struct stat st;
 103
 104                 lockfd = flopen(group_file, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 105                 if (lockfd == -1) {
 106                         if (errno == EWOULDBLOCK) {
 107                                 errx(1, "the group file is busy");
 108                         } else {
 109                                 err(1, "could not lock the group file: ");
 110                         }
 111                 }
 112                 if (fstat(lockfd, &st) == -1)
 113                         err(1, "fstat() failed: ");
 114                 if (st.st_nlink != 0)
 115                         break;
 116                 close(lockfd);
 117                 lockfd = -1;
 118         }
 119         return (lockfd);
 120 }
 121
 122 /*
 123  * Create and open a presmuably safe temp file for editing group data
 124  */
 125 int
 126 gr_tmp(int mfd)
 127 {
 128         char buf[8192];
 129         ssize_t nr;
 130         const char *p;
 131         int tfd;
 132
 133         if (*group_file == '\0')
 134                 return (-1);
 135         if ((p = strrchr(group_file, '/')))
 136                 ++p;
 137         else
 138                 p = group_file;
 139         if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
 140                 (int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
 141                 errno = ENAMETOOLONG;
 142                 return (-1);
 143         }
 144         if ((tfd = mkstemp(tempname)) == -1)
 145                 return (-1);
 146         if (mfd != -1) {
 147                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 148                         if (write(tfd, buf, (size_t)nr) != nr)
 149                                 break;
 150                 if (nr != 0) {
 151                         unlink(tempname);
 152                         *tempname = '\0';
 153                         close(tfd);
 154                         return (-1);
 155                 }
 156         }
 157         return (tfd);
 158 }
 159
 160 /*
 161  * Copy the group file from one descriptor to another, replacing, deleting
 162  * or adding a single record on the way.
 163  */
 164 int
 165 gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
 166 {
 167         char buf[8192], *end, *line, *p, *q, *r, t;
 168         struct group *fgr;
 169         const struct group *sgr;
 170         size_t len;
 171         int eof, readlen;
 172
 173         if (old_gr == NULL && gr == NULL)
 174                 return(-1);
 175
 176         sgr = old_gr;
 177         /* deleting a group */
 178         if (gr == NULL) {
 179                 line = NULL;
 180         } else {
 181                 if ((line = gr_make(gr)) == NULL)
 182                         return (-1);
 183         }
 184
 185         /* adding a group */
 186         if (sgr == NULL)
 187                 sgr = gr;
 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         if (chmod(tempname, 0644) != 0)
 322                 return (-1);
 323
 324         return (rename(tempname, group_file));
 325 }
 326
 327 /*
 328  * Clean up. Preserves errno for the caller's convenience.
 329  */
 330 void
 331 gr_fini(void)
 332 {
 333         int serrno;
 334
 335         if (!initialized)
 336                 return;
 337         initialized = 0;
 338         serrno = errno;
 339         if (*tempname != '\0') {
 340                 unlink(tempname);
 341                 *tempname = '\0';
 342         }
 343         if (lockfd != -1)
 344                 close(lockfd);
 345         errno = serrno;
 346 }
 347
 348 /*
 349  * Compares two struct group's.
 350  */
 351 int
 352 gr_equal(const struct group *gr1, const struct group *gr2)
 353 {
 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         /*
 370          * Check all members in both groups.
 371          * getgrnam can return gr_mem with a pointer to NULL.
 372          * gr_dup and gr_add strip out this superfluous NULL, setting
 373          * gr_mem to NULL for no members.
 374         */
 375         if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
 376                 int i;
 377
 378                 for (i = 0;
 379                     gr1->gr_mem[i] != NULL && gr2->gr_mem[i] != NULL; i++) {
 380                         if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
 381                                 return (false);
 382                 }
 383                 if (gr1->gr_mem[i] != NULL || gr2->gr_mem[i] != NULL)
 384                         return (false);
 385         } else if (gr1->gr_mem != NULL && gr1->gr_mem[0] != NULL) {
 386                 return (false);
 387         } else if (gr2->gr_mem != NULL && gr2->gr_mem[0] != NULL) {
 388                 return (false);
 389         }
 390
 391         return (true);
 392 }
 393
 394 /*
 395  * Make a group line out of a struct group.
 396  */
 397 char *
 398 gr_make(const struct group *gr)
 399 {
 400         const char *group_line_format = "%s:%s:%ju:";
 401         const char *sep;
 402         char *line;
 403         char *p;
 404         size_t line_size;
 405         int ndx;
 406
 407         /* Calculate the length of the group line. */
 408         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 409             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 410         if (gr->gr_mem != NULL) {
 411                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 412                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 413                 if (ndx > 0)
 414                         line_size--;
 415         }
 416
 417         /* Create the group line and fill it. */
 418         if ((line = p = malloc(line_size)) == NULL)
 419                 return (NULL);
 420         p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
 421             (uintmax_t)gr->gr_gid);
 422         if (gr->gr_mem != NULL) {
 423                 sep = "";
 424                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 425                         p = stpcpy(p, sep);
 426                         p = stpcpy(p, gr->gr_mem[ndx]);
 427                         sep = ",";
 428                 }
 429         }
 430
 431         return (line);
 432 }
 433
 434 /*
 435  * Duplicate a struct group.
 436  */
 437 struct group *
 438 gr_dup(const struct group *gr)
 439 {
 440         return (gr_add(gr, NULL));
 441 }
 442 /*
 443  * Add a new member name to a struct group.
 444  */
 445 struct group *
 446 gr_add(const struct group *gr, const char *newmember)
 447 {
 448         char *mem;
 449         size_t len;
 450         int num_mem;
 451
 452         num_mem = 0;
 453         len = grmemlen(gr, newmember, &num_mem);
 454         /* Create new group and copy old group into it. */
 455         if ((mem = malloc(len)) == NULL)
 456                 return (NULL);
 457         return (grcopy(gr, mem, newmember, num_mem));
 458 }
 459
 460 /* It is safer to walk the pointers given at gr_mem since there is no
 461  * guarantee the gr_mem + strings are contiguous in the given struct group
 462  * but compactify the new group into the following form.
 463  *
 464  * The new struct is laid out like this in memory. The example given is
 465  * for a group with two members only.
 466  *
 467  * {
 468  * (char *name)
 469  * (char *passwd)
 470  * (int gid)
 471  * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
 472  * gr_mem area
 473  * (member1 *)
 474  * (member2 *)
 475  * (NULL)
 476  * (name string)
 477  * (passwd string)
 478  * (member1 string)
 479  * (member2 string)
 480  * }
 481  */
 482 /*
 483  * Copy the contents of a group plus given name to a preallocated group struct
 484  */
 485 static struct group *
 486 grcopy(const struct group *gr, char *dst, const char *name, int ndx)
 487 {
 488         int i;
 489         struct group *newgr;
 490
 491         newgr = (struct group *)(void *)dst;    /* avoid alignment warning */
 492         dst += sizeof(*newgr);
 493         if (ndx != 0) {
 494                 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */
 495                 dst += (ndx + 1) * sizeof(*newgr->gr_mem);
 496         } else
 497                 newgr->gr_mem = NULL;
 498         if (gr->gr_name != NULL) {
 499                 newgr->gr_name = dst;
 500                 dst = stpcpy(dst, gr->gr_name) + 1;
 501         } else
 502                 newgr->gr_name = NULL;
 503         if (gr->gr_passwd != NULL) {
 504                 newgr->gr_passwd = dst;
 505                 dst = stpcpy(dst, gr->gr_passwd) + 1;
 506         } else
 507                 newgr->gr_passwd = NULL;
 508         newgr->gr_gid = gr->gr_gid;
 509         i = 0;
 510         /* Original group struct might have a NULL gr_mem */
 511         if (gr->gr_mem != NULL) {
 512                 for (; gr->gr_mem[i] != NULL; i++) {
 513                         newgr->gr_mem[i] = dst;
 514                         dst = stpcpy(dst, gr->gr_mem[i]) + 1;
 515                 }
 516         }
 517         /* If name is not NULL, newgr->gr_mem is known to be not NULL */
 518         if (name != NULL) {
 519                 newgr->gr_mem[i++] = dst;
 520                 dst = stpcpy(dst, name) + 1;
 521         }
 522         /* if newgr->gr_mem is not NULL add NULL marker */
 523         if (newgr->gr_mem != NULL)
 524                 newgr->gr_mem[i] = NULL;
 525
 526         return (newgr);
 527 }
 528
 529 /*
 530  *  Calculate length of a struct group + given name
 531  */
 532 static size_t
 533 grmemlen(const struct group *gr, const char *name, int *num_mem)
 534 {
 535         size_t len;
 536         int i;
 537
 538         if (gr == NULL)
 539                 return (0);
 540         /* Calculate size of the group. */
 541         len = sizeof(*gr);
 542         if (gr->gr_name != NULL)
 543                 len += strlen(gr->gr_name) + 1;
 544         if (gr->gr_passwd != NULL)
 545                 len += strlen(gr->gr_passwd) + 1;
 546         i = 0;
 547         if (gr->gr_mem != NULL) {
 548                 for (; gr->gr_mem[i] != NULL; i++) {
 549                         len += strlen(gr->gr_mem[i]) + 1;
 550                         len += sizeof(*gr->gr_mem);
 551                 }
 552         }
 553         if (name != NULL) {
 554                 i++;
 555                 len += strlen(name) + 1;
 556                 len += sizeof(*gr->gr_mem);
 557         }
 558         /* Allow for NULL pointer */
 559         if (i != 0)
 560                 len += sizeof(*gr->gr_mem);
 561         *num_mem = i;
 562         return(len);
 563 }
 564
 565 /*
 566  * Scan a line and place it into a group structure.
 567  */
 568 static bool
 569 __gr_scan(char *line, struct group *gr)
 570 {
 571         char *loc;
 572         int ndx;
 573
 574         /* Assign non-member information to structure. */
 575         gr->gr_name = line;
 576         if ((loc = strchr(line, ':')) == NULL)
 577                 return (false);
 578         *loc = '\0';
 579         gr->gr_passwd = loc + 1;
 580         if (*gr->gr_passwd == ':')
 581                 *gr->gr_passwd = '\0';
 582         else {
 583                 if ((loc = strchr(loc + 1, ':')) == NULL)
 584                         return (false);
 585                 *loc = '\0';
 586         }
 587         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 588                 return (false);
 589
 590         /* Assign member information to structure. */
 591         if ((loc = strchr(loc + 1, ':')) == NULL)
 592                 return (false);
 593         line = loc + 1;
 594         gr->gr_mem = NULL;
 595         ndx = 0;
 596         do {
 597                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 598                     (ndx + 1));
 599                 if (gr->gr_mem == NULL)
 600                         return (false);
 601
 602                 /* Skip locations without members (i.e., empty string). */
 603                 do {
 604                         gr->gr_mem[ndx] = strsep(&line, ",");
 605                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 606         } while (gr->gr_mem[ndx++] != NULL);
 607
 608         return (true);
 609 }
 610
 611 /*
 612  * Create a struct group from a line.
 613  */
 614 struct group *
 615 gr_scan(const char *line)
 616 {
 617         struct group gr;
 618         char *line_copy;
 619         struct group *new_gr;
 620
 621         if ((line_copy = strdup(line)) == NULL)
 622                 return (NULL);
 623         if (!__gr_scan(line_copy, &gr)) {
 624                 free(line_copy);
 625                 return (NULL);
 626         }
 627         new_gr = gr_dup(&gr);
 628         free(line_copy);
 629         if (gr.gr_mem != NULL)
 630                 free(gr.gr_mem);
 631
 632         return (new_gr);
 633 }