lib/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  * $FreeBSD: head/lib/libutil/gr_util.c 248102 2013-03-09 13:30:06Z db $
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/errno.h>
  31 #include <sys/stat.h>
  32
  33 #include <ctype.h>
  34 #include <err.h>
  35 #include <fcntl.h>
  36 #include <grp.h>
  37 #include <inttypes.h>
  38 #include <libutil.h>
  39 #include <paths.h>
  40 #include <stdbool.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45
  46 static int lockfd = -1;
  47 static char group_dir[PATH_MAX];
  48 static char group_file[PATH_MAX];
  49 static char tempname[PATH_MAX];
  50 static int initialized;
  51 static size_t grmemlen(const struct group *, const char *, int *);
  52 static struct group *grcopy(const struct group *gr, char *mem, const char *, int ndx);
  53
  54 /*
  55  * Initialize statics
  56  */
  57 int
  58 gr_init(const char *dir, const char *group)
  59 {
  60
  61         if (dir == NULL) {
  62                 strcpy(group_dir, _PATH_ETC);
  63         } else {
  64                 if (strlen(dir) >= sizeof(group_dir)) {
  65                         errno = ENAMETOOLONG;
  66                         return (-1);
  67                 }
  68                 strcpy(group_dir, dir);
  69         }
  70
  71         if (group == NULL) {
  72                 if (dir == NULL) {
  73                         strcpy(group_file, _PATH_GROUP);
  74                 } else if (snprintf(group_file, sizeof(group_file), "%s/group",
  75                         group_dir) > (int)sizeof(group_file)) {
  76                         errno = ENAMETOOLONG;
  77                         return (-1);
  78                 }
  79         } else {
  80                 if (strlen(group) >= sizeof(group_file)) {
  81                         errno = ENAMETOOLONG;
  82                         return (-1);
  83                 }
  84                 strcpy(group_file, group);
  85         }
  86
  87         initialized = 1;
  88         return (0);
  89 }
  90
  91 /*
  92  * Lock the group file
  93  */
  94 int
  95 gr_lock(void)
  96 {
  97         if (*group_file == '\0')
  98                 return (-1);
  99
 100         for (;;) {
 101                 struct stat st;
 102
 103                 lockfd = flopen(group_file, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 104                 if (lockfd == -1) {
 105                         if (errno == EWOULDBLOCK) {
 106                                 errx(1, "the group file is busy");
 107                         } else {
 108                                 err(1, "could not lock the group file: ");
 109                         }
 110                 }
 111                 if (fstat(lockfd, &st) == -1)
 112                         err(1, "fstat() failed: ");
 113                 if (st.st_nlink != 0)
 114                         break;
 115                 close(lockfd);
 116                 lockfd = -1;
 117         }
 118         return (lockfd);
 119 }
 120
 121 /*
 122  * Create and open a presmuably safe temp file for editing group data
 123  */
 124 int
 125 gr_tmp(int mfd)
 126 {
 127         char buf[8192];
 128         ssize_t nr;
 129         const char *p;
 130         int tfd;
 131
 132         if (*group_file == '\0')
 133                 return (-1);
 134         if ((p = strrchr(group_file, '/')))
 135                 ++p;
 136         else
 137                 p = group_file;
 138         if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
 139                 (int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
 140                 errno = ENAMETOOLONG;
 141                 return (-1);
 142         }
 143         if ((tfd = mkstemp(tempname)) == -1)
 144                 return (-1);
 145         if (mfd != -1) {
 146                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 147                         if (write(tfd, buf, (size_t)nr) != nr)
 148                                 break;
 149                 if (nr != 0) {
 150                         unlink(tempname);
 151                         *tempname = '\0';
 152                         close(tfd);
 153                         return (-1);
 154                 }
 155         }
 156         return (tfd);
 157 }
 158
 159 /*
 160  * Copy the group file from one descriptor to another, replacing, deleting
 161  * or adding a single record on the way.
 162  */
 163 int
 164 gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
 165 {
 166         char buf[8192], *end, *line, *p, *q, *r, t;
 167         struct group *fgr;
 168         const struct group *sgr;
 169         size_t len;
 170         int eof, readlen;
 171
 172         sgr = gr;
 173         if (gr == NULL) {
 174                 line = NULL;
 175                 if (old_gr == NULL)
 176                         return (-1);
 177                 sgr = old_gr;
 178         } else if ((line = gr_make(gr)) == NULL)
 179                 return (-1);
 180
 181         eof = 0;
 182         len = 0;
 183         p = q = end = buf;
 184         for (;;) {
 185                 /* find the end of the current line */
 186                 for (p = q; q < end && *q != '\0'; ++q)
 187                         if (*q == '\n')
 188                                 break;
 189
 190                 /* if we don't have a complete line, fill up the buffer */
 191                 if (q >= end) {
 192                         if (eof)
 193                                 break;
 194                         if ((size_t)(q - p) >= sizeof(buf)) {
 195                                 warnx("group line too long");
 196                                 errno = EINVAL; /* hack */
 197                                 goto err;
 198                         }
 199                         if (p < end) {
 200                                 q = memmove(buf, p, end -p);
 201                                 end -= p - buf;
 202                         } else {
 203                                 p = q = end = buf;
 204                         }
 205                         readlen = read(ffd, end, sizeof(buf) - (end -buf));
 206                         if (readlen == -1)
 207                                 goto err;
 208                         else
 209                                 len = (size_t)readlen;
 210                         if (len == 0 && p == buf)
 211                                 break;
 212                         end += len;
 213                         len = end - buf;
 214                         if (len < (ssize_t)sizeof(buf)) {
 215                                 eof = 1;
 216                                 if (len > 0 && buf[len -1] != '\n')
 217                                         ++len, *end++ = '\n';
 218                         }
 219                         continue;
 220                 }
 221
 222                 /* is it a blank line or a comment? */
 223                 for (r = p; r < q && isspace(*r); ++r)
 224                         /* nothing */;
 225                 if (r == q || *r == '#') {
 226                         /* yep */
 227                         if (write(tfd, p, q -p + 1) != q - p + 1)
 228                                 goto err;
 229                         ++q;
 230                         continue;
 231                 }
 232
 233                 /* is it the one we're looking for? */
 234
 235                 t = *q;
 236                 *q = '\0';
 237
 238                 fgr = gr_scan(r);
 239
 240                 /* fgr is either a struct group for the current line,
 241                  * or NULL if the line is malformed.
 242                  */
 243
 244                 *q = t;
 245                 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
 246                         /* nope */
 247                         if (fgr != NULL)
 248                                 free(fgr);
 249                         if (write(tfd, p, q - p + 1) != q - p + 1)
 250                                 goto err;
 251                         ++q;
 252                         continue;
 253                 }
 254                 if (old_gr && !gr_equal(fgr, old_gr)) {
 255                         warnx("entry inconsistent");
 256                         free(fgr);
 257                         errno = EINVAL; /* hack */
 258                         goto err;
 259                 }
 260                 free(fgr);
 261
 262                 /* it is, replace or remove it */
 263                 if (line != NULL) {
 264                         len = strlen(line);
 265                         if (write(tfd, line, len) != (int) len)
 266                                 goto err;
 267                 } else {
 268                         /* when removed, avoid the \n */
 269                         q++;
 270                 }
 271                 /* we're done, just copy the rest over */
 272                 for (;;) {
 273                         if (write(tfd, q, end - q) != end - q)
 274                                 goto err;
 275                         q = buf;
 276                         readlen = read(ffd, buf, sizeof(buf));
 277                         if (readlen == 0)
 278                                 break;
 279                         else
 280                                 len = (size_t)readlen;
 281                         if (readlen == -1)
 282                                 goto err;
 283                         end = buf + len;
 284                 }
 285                 goto done;
 286         }
 287
 288         /* if we got here, we didn't find the old entry */
 289         if (line == NULL) {
 290                 errno = ENOENT;
 291                 goto err;
 292         }
 293         len = strlen(line);
 294         if ((size_t)write(tfd, line, len) != len ||
 295            write(tfd, "\n", 1) != 1)
 296                 goto err;
 297  done:
 298         if (line != NULL)
 299                 free(line);
 300         return (0);
 301  err:
 302         if (line != NULL)
 303                 free(line);
 304         return (-1);
 305 }
 306
 307 /*
 308  * Regenerate the group file
 309  */
 310 int
 311 gr_mkdb(void)
 312 {
 313         if (chmod(tempname, 0644) != 0)
 314                 return (-1);
 315
 316         return (rename(tempname, group_file));
 317 }
 318
 319 /*
 320  * Clean up. Preserves errno for the caller's convenience.
 321  */
 322 void
 323 gr_fini(void)
 324 {
 325         int serrno;
 326
 327         if (!initialized)
 328                 return;
 329         initialized = 0;
 330         serrno = errno;
 331         if (*tempname != '\0') {
 332                 unlink(tempname);
 333                 *tempname = '\0';
 334         }
 335         if (lockfd != -1)
 336                 close(lockfd);
 337         errno = serrno;
 338 }
 339
 340 /*
 341  * Compares two struct group's.
 342  */
 343 int
 344 gr_equal(const struct group *gr1, const struct group *gr2)
 345 {
 346         int gr1_ndx;
 347         int gr2_ndx;
 348
 349         /* Check that the non-member information is the same. */
 350         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 351                 if (gr1->gr_name != gr2->gr_name)
 352                         return (false);
 353         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 354                 return (false);
 355         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 356                 if (gr1->gr_passwd != gr2->gr_passwd)
 357                         return (false);
 358         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 359                 return (false);
 360         if (gr1->gr_gid != gr2->gr_gid)
 361                 return (false);
 362
 363         /* Check all members in both groups.
 364          * getgrnam can return gr_mem with a pointer to NULL.
 365          * gr_dup and gr_add strip out this superfluous NULL, setting
 366          * gr_mem to NULL for no members.
 367         */
 368         if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
 369                 int i;
 370
 371                 for (i = 0; gr1->gr_mem[i] != NULL; i++) {
 372                         if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
 373                         return (false);
 374                                 }
 375                 }
 376         /* Count number of members in both structs */
 377         gr2_ndx = 0;
 378         if (gr2->gr_mem != NULL)
 379                 for(; gr2->gr_mem[gr2_ndx] != NULL; gr2_ndx++)
 380                         /* empty */;
 381         gr1_ndx = 0;
 382         if (gr1->gr_mem != NULL)
 383                 for(; gr1->gr_mem[gr1_ndx] != NULL; gr1_ndx++)
 384                         /* empty */;
 385         if (gr1_ndx != gr2_ndx)
 386                         return (false);
 387
 388         return (true);
 389 }
 390
 391 /*
 392  * Make a group line out of a struct group.
 393  */
 394 char *
 395 gr_make(const struct group *gr)
 396 {
 397         const char *group_line_format = "%s:%s:%ju:";
 398         const char *sep;
 399         char *line;
 400         char *p;
 401         size_t line_size;
 402         int ndx;
 403
 404         /* Calculate the length of the group line. */
 405         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 406             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 407         if (gr->gr_mem != NULL) {
 408                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 409                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 410                 if (ndx > 0)
 411                         line_size--;
 412         }
 413
 414         /* Create the group line and fill it. */
 415         if ((line = p = malloc(line_size)) == NULL)
 416                 return (NULL);
 417         p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
 418             (uintmax_t)gr->gr_gid);
 419         if (gr->gr_mem != NULL) {
 420                 sep = "";
 421                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 422                         p = stpcpy(p, sep);
 423                         p = stpcpy(p, gr->gr_mem[ndx]);
 424                         sep = ",";
 425                 }
 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         return (gr_add(gr, NULL));
 438 }
 439 /*
 440  * Add a new member name to a struct group.
 441  */
 442 struct group *
 443 gr_add(const struct group *gr, const char *newmember)
 444 {
 445         char *mem;
 446         size_t len;
 447         int num_mem;
 448
 449         num_mem = 0;
 450         len = grmemlen(gr, newmember, &num_mem);
 451         /* Create new group and copy old group into it. */
 452         if ((mem = malloc(len)) == NULL)
 453                 return (NULL);
 454         return (grcopy(gr, mem, newmember, num_mem));
 455 }
 456
 457 /* It is safer to walk the pointers given at gr_mem since there is no
 458  * guarantee the gr_mem + strings are contiguous in the given struct group
 459  * but compactify the new group into the following form.
 460  *
 461  * The new struct is laid out like this in memory. The example given is
 462  * for a group with two members only.
 463  *
 464  * {
 465  * (char *name)
 466  * (char *passwd)
 467  * (int gid)
 468  * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
 469  * gr_mem area
 470  * (member1 *)
 471  * (member2 *)
 472  * (NULL)
 473  * (name string)
 474  * (passwd string)
 475  * (member1 string)
 476  * (member2 string)
 477  * }
 478  */
 479 /*
 480  * Copy the contents of a group plus given name to a preallocated group struct
 481  */
 482 static struct group *
 483 grcopy(const struct group *gr, char *dst, const char *name, int ndx)
 484 {
 485         int i;
 486         struct group *newgr;
 487
 488         newgr = (struct group *)(void *)dst;    /* avoid alignment warning */
 489         dst += sizeof(*newgr);
 490         if (ndx != 0) {
 491                 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */
 492                 dst += (ndx + 1) * sizeof(*newgr->gr_mem);
 493         } else
 494                 newgr->gr_mem = NULL;
 495         if (gr->gr_name != NULL) {
 496                 newgr->gr_name = dst;
 497                 dst = stpcpy(dst, gr->gr_name) + 1;
 498         } else
 499                 newgr->gr_name = NULL;
 500         if (gr->gr_passwd != NULL) {
 501                 newgr->gr_passwd = dst;
 502                 dst = stpcpy(dst, gr->gr_passwd) + 1;
 503         } else
 504                 newgr->gr_passwd = NULL;
 505         newgr->gr_gid = gr->gr_gid;
 506         i = 0;
 507         /* Original group struct might have a NULL gr_mem */
 508         if (gr->gr_mem != NULL) {
 509                 for (; gr->gr_mem[i] != NULL; i++) {
 510                         newgr->gr_mem[i] = dst;
 511                         dst = stpcpy(dst, gr->gr_mem[i]) + 1;
 512                 }
 513         }
 514         /* If name is not NULL, newgr->gr_mem is known to be not NULL */
 515         if (name != NULL) {
 516                 newgr->gr_mem[i++] = dst;
 517                 dst = stpcpy(dst, name) + 1;
 518         }
 519         /* if newgr->gr_mem is not NULL add NULL marker */
 520         if (newgr->gr_mem != NULL)
 521                 newgr->gr_mem[i] = NULL;
 522
 523         return (newgr);
 524 }
 525
 526 /*
 527  *  Calculate length of a struct group + given name
 528  */
 529 static size_t
 530 grmemlen(const struct group *gr, const char *name, int *num_mem)
 531 {
 532         size_t len;
 533         int i;
 534
 535         if (gr == NULL)
 536                 return (0);
 537         /* Calculate size of the group. */
 538         len = sizeof(*gr);
 539         if (gr->gr_name != NULL)
 540                 len += strlen(gr->gr_name) + 1;
 541         if (gr->gr_passwd != NULL)
 542                 len += strlen(gr->gr_passwd) + 1;
 543         i = 0;
 544         if (gr->gr_mem != NULL) {
 545                 for (; gr->gr_mem[i] != NULL; i++) {
 546                         len += strlen(gr->gr_mem[i]) + 1;
 547                         len += sizeof(*gr->gr_mem);
 548         }
 549         }
 550         if (name != NULL) {
 551                 i++;
 552                 len += strlen(name) + 1;
 553                 len += sizeof(*gr->gr_mem);
 554                 }
 555         /* Allow for NULL pointer */
 556         if (i != 0)
 557                 len += sizeof(*gr->gr_mem);
 558         *num_mem = i;
 559         return(len);
 560 }
 561
 562 /*
 563  * Scan a line and place it into a group structure.
 564  */
 565 static bool
 566 __gr_scan(char *line, struct group *gr)
 567 {
 568         char *loc;
 569         int ndx;
 570
 571         /* Assign non-member information to structure. */
 572         gr->gr_name = line;
 573         if ((loc = strchr(line, ':')) == NULL)
 574                 return (false);
 575         *loc = '\0';
 576         gr->gr_passwd = loc + 1;
 577         if (*gr->gr_passwd == ':')
 578                 *gr->gr_passwd = '\0';
 579         else {
 580                 if ((loc = strchr(loc + 1, ':')) == NULL)
 581                         return (false);
 582                 *loc = '\0';
 583         }
 584         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 585                 return (false);
 586
 587         /* Assign member information to structure. */
 588         if ((loc = strchr(loc + 1, ':')) == NULL)
 589                 return (false);
 590         line = loc + 1;
 591         gr->gr_mem = NULL;
 592         ndx = 0;
 593         do {
 594                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 595                     (ndx + 1));
 596                 if (gr->gr_mem == NULL)
 597                         return (false);
 598
 599                 /* Skip locations without members (i.e., empty string). */
 600                 do {
 601                         gr->gr_mem[ndx] = strsep(&line, ",");
 602                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 603         } while (gr->gr_mem[ndx++] != NULL);
 604
 605         return (true);
 606 }
 607
 608 /*
 609  * Create a struct group from a line.
 610  */
 611 struct group *
 612 gr_scan(const char *line)
 613 {
 614         struct group gr;
 615         char *line_copy;
 616         struct group *new_gr;
 617
 618         if ((line_copy = strdup(line)) == NULL)
 619                 return (NULL);
 620         if (!__gr_scan(line_copy, &gr)) {
 621                 free(line_copy);
 622                 return (NULL);
 623         }
 624         new_gr = gr_dup(&gr);
 625         free(line_copy);
 626         if (gr.gr_mem != NULL)
 627                 free(gr.gr_mem);
 628
 629         return (new_gr);
 630 }