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         sgr = gr;
 174         if (gr == NULL) {
 175                 line = NULL;
 176                 if (old_gr == NULL)
 177                         return (-1);
 178                 sgr = old_gr;
 179         } else if ((line = gr_make(gr)) == NULL)
 180                 return (-1);
 181
 182         eof = 0;
 183         len = 0;
 184         p = q = end = buf;
 185         for (;;) {
 186                 /* find the end of the current line */
 187                 for (p = q; q < end && *q != '\0'; ++q)
 188                         if (*q == '\n')
 189                                 break;
 190
 191                 /* if we don't have a complete line, fill up the buffer */
 192                 if (q >= end) {
 193                         if (eof)
 194                                 break;
 195                         if ((size_t)(q - p) >= sizeof(buf)) {
 196                                 warnx("group line too long");
 197                                 errno = EINVAL; /* hack */
 198                                 goto err;
 199                         }
 200                         if (p < end) {
 201                                 q = memmove(buf, p, end -p);
 202                                 end -= p - buf;
 203                         } else {
 204                                 p = q = end = buf;
 205                         }
 206                         readlen = read(ffd, end, sizeof(buf) - (end -buf));
 207                         if (readlen == -1)
 208                                 goto err;
 209                         else
 210                                 len = (size_t)readlen;
 211                         if (len == 0 && p == buf)
 212                                 break;
 213                         end += len;
 214                         len = end - buf;
 215                         if (len < (ssize_t)sizeof(buf)) {
 216                                 eof = 1;
 217                                 if (len > 0 && buf[len -1] != '\n')
 218                                         ++len, *end++ = '\n';
 219                         }
 220                         continue;
 221                 }
 222
 223                 /* is it a blank line or a comment? */
 224                 for (r = p; r < q && isspace(*r); ++r)
 225                         /* nothing */;
 226                 if (r == q || *r == '#') {
 227                         /* yep */
 228                         if (write(tfd, p, q -p + 1) != q - p + 1)
 229                                 goto err;
 230                         ++q;
 231                         continue;
 232                 }
 233
 234                 /* is it the one we're looking for? */
 235
 236                 t = *q;
 237                 *q = '\0';
 238
 239                 fgr = gr_scan(r);
 240
 241                 /* fgr is either a struct group for the current line,
 242                  * or NULL if the line is malformed.
 243                  */
 244
 245                 *q = t;
 246                 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
 247                         /* nope */
 248                         if (fgr != NULL)
 249                                 free(fgr);
 250                         if (write(tfd, p, q - p + 1) != q - p + 1)
 251                                 goto err;
 252                         ++q;
 253                         continue;
 254                 }
 255                 if (old_gr && !gr_equal(fgr, old_gr)) {
 256                         warnx("entry inconsistent");
 257                         free(fgr);
 258                         errno = EINVAL; /* hack */
 259                         goto err;
 260                 }
 261                 free(fgr);
 262
 263                 /* it is, replace or remove it */
 264                 if (line != NULL) {
 265                         len = strlen(line);
 266                         if (write(tfd, line, len) != (int) len)
 267                                 goto err;
 268                 } else {
 269                         /* when removed, avoid the \n */
 270                         q++;
 271                 }
 272                 /* we're done, just copy the rest over */
 273                 for (;;) {
 274                         if (write(tfd, q, end - q) != end - q)
 275                                 goto err;
 276                         q = buf;
 277                         readlen = read(ffd, buf, sizeof(buf));
 278                         if (readlen == 0)
 279                                 break;
 280                         else
 281                                 len = (size_t)readlen;
 282                         if (readlen == -1)
 283                                 goto err;
 284                         end = buf + len;
 285                 }
 286                 goto done;
 287         }
 288
 289         /* if we got here, we didn't find the old entry */
 290         if (line == NULL) {
 291                 errno = ENOENT;
 292                 goto err;
 293         }
 294         len = strlen(line);
 295         if ((size_t)write(tfd, line, len) != len ||
 296            write(tfd, "\n", 1) != 1)
 297                 goto err;
 298  done:
 299         if (line != NULL)
 300                 free(line);
 301         return (0);
 302  err:
 303         if (line != NULL)
 304                 free(line);
 305         return (-1);
 306 }
 307
 308 /*
 309  * Regenerate the group file
 310  */
 311 int
 312 gr_mkdb(void)
 313 {
 314         if (chmod(tempname, 0644) != 0)
 315                 return (-1);
 316
 317         return (rename(tempname, group_file));
 318 }
 319
 320 /*
 321  * Clean up. Preserves errno for the caller's convenience.
 322  */
 323 void
 324 gr_fini(void)
 325 {
 326         int serrno;
 327
 328         if (!initialized)
 329                 return;
 330         initialized = 0;
 331         serrno = errno;
 332         if (*tempname != '\0') {
 333                 unlink(tempname);
 334                 *tempname = '\0';
 335         }
 336         if (lockfd != -1)
 337                 close(lockfd);
 338         errno = serrno;
 339 }
 340
 341 /*
 342  * Compares two struct group's.
 343  */
 344 int
 345 gr_equal(const struct group *gr1, const struct group *gr2)
 346 {
 347         int gr1_ndx;
 348         int gr2_ndx;
 349
 350         /* Check that the non-member information is the same. */
 351         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 352                 if (gr1->gr_name != gr2->gr_name)
 353                         return (false);
 354         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 355                 return (false);
 356         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 357                 if (gr1->gr_passwd != gr2->gr_passwd)
 358                         return (false);
 359         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 360                 return (false);
 361         if (gr1->gr_gid != gr2->gr_gid)
 362                 return (false);
 363
 364         /* Check all members in both groups.
 365          * getgrnam can return gr_mem with a pointer to NULL.
 366          * gr_dup and gr_add strip out this superfluous NULL, setting
 367          * gr_mem to NULL for no members.
 368         */
 369         if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
 370                 int i;
 371
 372                 for (i = 0; gr1->gr_mem[i] != NULL; i++) {
 373                         if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
 374                                 return (false);
 375                 }
 376         }
 377         /* Count number of members in both structs */
 378         gr2_ndx = 0;
 379         if (gr2->gr_mem != NULL)
 380                 for(; gr2->gr_mem[gr2_ndx] != NULL; gr2_ndx++)
 381                         /* empty */;
 382         gr1_ndx = 0;
 383         if (gr1->gr_mem != NULL)
 384                 for(; gr1->gr_mem[gr1_ndx] != NULL; gr1_ndx++)
 385                         /* empty */;
 386         if (gr1_ndx != gr2_ndx)
 387                 return (false);
 388
 389         return (true);
 390 }
 391
 392 /*
 393  * Make a group line out of a struct group.
 394  */
 395 char *
 396 gr_make(const struct group *gr)
 397 {
 398         const char *group_line_format = "%s:%s:%ju:";
 399         const char *sep;
 400         char *line;
 401         char *p;
 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 = p = malloc(line_size)) == NULL)
 417                 return (NULL);
 418         p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
 419             (uintmax_t)gr->gr_gid);
 420         if (gr->gr_mem != NULL) {
 421                 sep = "";
 422                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 423                         p = stpcpy(p, sep);
 424                         p = stpcpy(p, gr->gr_mem[ndx]);
 425                         sep = ",";
 426                 }
 427         }
 428
 429         return (line);
 430 }
 431
 432 /*
 433  * Duplicate a struct group.
 434  */
 435 struct group *
 436 gr_dup(const struct group *gr)
 437 {
 438         return (gr_add(gr, NULL));
 439 }
 440 /*
 441  * Add a new member name to a struct group.
 442  */
 443 struct group *
 444 gr_add(const struct group *gr, const char *newmember)
 445 {
 446         char *mem;
 447         size_t len;
 448         int num_mem;
 449
 450         num_mem = 0;
 451         len = grmemlen(gr, newmember, &num_mem);
 452         /* Create new group and copy old group into it. */
 453         if ((mem = malloc(len)) == NULL)
 454                 return (NULL);
 455         return (grcopy(gr, mem, newmember, num_mem));
 456 }
 457
 458 /* It is safer to walk the pointers given at gr_mem since there is no
 459  * guarantee the gr_mem + strings are contiguous in the given struct group
 460  * but compactify the new group into the following form.
 461  *
 462  * The new struct is laid out like this in memory. The example given is
 463  * for a group with two members only.
 464  *
 465  * {
 466  * (char *name)
 467  * (char *passwd)
 468  * (int gid)
 469  * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
 470  * gr_mem area
 471  * (member1 *)
 472  * (member2 *)
 473  * (NULL)
 474  * (name string)
 475  * (passwd string)
 476  * (member1 string)
 477  * (member2 string)
 478  * }
 479  */
 480 /*
 481  * Copy the contents of a group plus given name to a preallocated group struct
 482  */
 483 static struct group *
 484 grcopy(const struct group *gr, char *dst, const char *name, int ndx)
 485 {
 486         int i;
 487         struct group *newgr;
 488
 489         newgr = (struct group *)(void *)dst;    /* avoid alignment warning */
 490         dst += sizeof(*newgr);
 491         if (ndx != 0) {
 492                 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */
 493                 dst += (ndx + 1) * sizeof(*newgr->gr_mem);
 494         } else
 495                 newgr->gr_mem = NULL;
 496         if (gr->gr_name != NULL) {
 497                 newgr->gr_name = dst;
 498                 dst = stpcpy(dst, gr->gr_name) + 1;
 499         } else
 500                 newgr->gr_name = NULL;
 501         if (gr->gr_passwd != NULL) {
 502                 newgr->gr_passwd = dst;
 503                 dst = stpcpy(dst, gr->gr_passwd) + 1;
 504         } else
 505                 newgr->gr_passwd = NULL;
 506         newgr->gr_gid = gr->gr_gid;
 507         i = 0;
 508         /* Original group struct might have a NULL gr_mem */
 509         if (gr->gr_mem != NULL) {
 510                 for (; gr->gr_mem[i] != NULL; i++) {
 511                         newgr->gr_mem[i] = dst;
 512                         dst = stpcpy(dst, gr->gr_mem[i]) + 1;
 513                 }
 514         }
 515         /* If name is not NULL, newgr->gr_mem is known to be not NULL */
 516         if (name != NULL) {
 517                 newgr->gr_mem[i++] = dst;
 518                 dst = stpcpy(dst, name) + 1;
 519         }
 520         /* if newgr->gr_mem is not NULL add NULL marker */
 521         if (newgr->gr_mem != NULL)
 522                 newgr->gr_mem[i] = NULL;
 523
 524         return (newgr);
 525 }
 526
 527 /*
 528  *  Calculate length of a struct group + given name
 529  */
 530 static size_t
 531 grmemlen(const struct group *gr, const char *name, int *num_mem)
 532 {
 533         size_t len;
 534         int i;
 535
 536         if (gr == NULL)
 537                 return (0);
 538         /* Calculate size of the group. */
 539         len = sizeof(*gr);
 540         if (gr->gr_name != NULL)
 541                 len += strlen(gr->gr_name) + 1;
 542         if (gr->gr_passwd != NULL)
 543                 len += strlen(gr->gr_passwd) + 1;
 544         i = 0;
 545         if (gr->gr_mem != NULL) {
 546                 for (; gr->gr_mem[i] != NULL; i++) {
 547                         len += strlen(gr->gr_mem[i]) + 1;
 548                         len += sizeof(*gr->gr_mem);
 549                 }
 550         }
 551         if (name != NULL) {
 552                 i++;
 553                 len += strlen(name) + 1;
 554                 len += sizeof(*gr->gr_mem);
 555         }
 556         /* Allow for NULL pointer */
 557         if (i != 0)
 558                 len += sizeof(*gr->gr_mem);
 559         *num_mem = i;
 560         return(len);
 561 }
 562
 563 /*
 564  * Scan a line and place it into a group structure.
 565  */
 566 static bool
 567 __gr_scan(char *line, struct group *gr)
 568 {
 569         char *loc;
 570         int ndx;
 571
 572         /* Assign non-member information to structure. */
 573         gr->gr_name = line;
 574         if ((loc = strchr(line, ':')) == NULL)
 575                 return (false);
 576         *loc = '\0';
 577         gr->gr_passwd = loc + 1;
 578         if (*gr->gr_passwd == ':')
 579                 *gr->gr_passwd = '\0';
 580         else {
 581                 if ((loc = strchr(loc + 1, ':')) == NULL)
 582                         return (false);
 583                 *loc = '\0';
 584         }
 585         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 586                 return (false);
 587
 588         /* Assign member information to structure. */
 589         if ((loc = strchr(loc + 1, ':')) == NULL)
 590                 return (false);
 591         line = loc + 1;
 592         gr->gr_mem = NULL;
 593         ndx = 0;
 594         do {
 595                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 596                     (ndx + 1));
 597                 if (gr->gr_mem == NULL)
 598                         return (false);
 599
 600                 /* Skip locations without members (i.e., empty string). */
 601                 do {
 602                         gr->gr_mem[ndx] = strsep(&line, ",");
 603                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 604         } while (gr->gr_mem[ndx++] != NULL);
 605
 606         return (true);
 607 }
 608
 609 /*
 610  * Create a struct group from a line.
 611  */
 612 struct group *
 613 gr_scan(const char *line)
 614 {
 615         struct group gr;
 616         char *line_copy;
 617         struct group *new_gr;
 618
 619         if ((line_copy = strdup(line)) == NULL)
 620                 return (NULL);
 621         if (!__gr_scan(line_copy, &gr)) {
 622                 free(line_copy);
 623                 return (NULL);
 624         }
 625         new_gr = gr_dup(&gr);
 626         free(line_copy);
 627         if (gr.gr_mem != NULL)
 628                 free(gr.gr_mem);
 629
 630         return (new_gr);
 631 }