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 = mkostemp(tempname, 0)) == -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, *end, *line, *p, *q, *r, *tmp;
 168         struct group *fgr;
 169         const struct group *sgr;
 170         size_t len, size;
 171         int eof, readlen;
 172         char t;
 173
 174         if (old_gr == NULL && gr == NULL)
 175                 return(-1);
 176
 177         sgr = old_gr;
 178         /* deleting a group */
 179         if (gr == NULL) {
 180                 line = NULL;
 181         } else {
 182                 if ((line = gr_make(gr)) == NULL)
 183                         return (-1);
 184         }
 185
 186         /* adding a group */
 187         if (sgr == NULL)
 188                 sgr = gr;
 189
 190         /* initialize the buffer */
 191         if ((buf = malloc(size = 1024)) == NULL)
 192                 goto err;
 193
 194         eof = 0;
 195         len = 0;
 196         p = q = end = buf;
 197         for (;;) {
 198                 /* find the end of the current line */
 199                 for (p = q; q < end && *q != '\0'; ++q)
 200                         if (*q == '\n')
 201                                 break;
 202
 203                 /* if we don't have a complete line, fill up the buffer */
 204                 if (q >= end) {
 205                         if (eof)
 206                                 break;
 207                         while ((size_t)(q - p) >= size) {
 208                                 if ((tmp = realloc(buf, size * 2)) == NULL) {
 209                                         warnx("group line too long");
 210                                         goto err;
 211                                 }
 212                                 p = tmp + (p - buf);
 213                                 q = tmp + (q - buf);
 214                                 end = tmp + (end - buf);
 215                                 buf = tmp;
 216                                 size = size * 2;
 217                         }
 218                         if (p < end) {
 219                                 q = memmove(buf, p, end -p);
 220                                 end -= p - buf;
 221                         } else {
 222                                 p = q = end = buf;
 223                         }
 224                         readlen = read(ffd, end, size - (end - buf));
 225                         if (readlen == -1)
 226                                 goto err;
 227                         else
 228                                 len = (size_t)readlen;
 229                         if (len == 0 && p == buf)
 230                                 break;
 231                         end += len;
 232                         len = end - buf;
 233                         if (len < size) {
 234                                 eof = 1;
 235                                 if (len > 0 && buf[len -1] != '\n')
 236                                         ++len, *end++ = '\n';
 237                         }
 238                         continue;
 239                 }
 240
 241                 /* is it a blank line or a comment? */
 242                 for (r = p; r < q && isspace(*r); ++r)
 243                         /* nothing */;
 244                 if (r == q || *r == '#') {
 245                         /* yep */
 246                         if (write(tfd, p, q -p + 1) != q - p + 1)
 247                                 goto err;
 248                         ++q;
 249                         continue;
 250                 }
 251
 252                 /* is it the one we're looking for? */
 253
 254                 t = *q;
 255                 *q = '\0';
 256
 257                 fgr = gr_scan(r);
 258
 259                 /* fgr is either a struct group for the current line,
 260                  * or NULL if the line is malformed.
 261                  */
 262
 263                 *q = t;
 264                 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
 265                         /* nope */
 266                         if (fgr != NULL)
 267                                 free(fgr);
 268                         if (write(tfd, p, q - p + 1) != q - p + 1)
 269                                 goto err;
 270                         ++q;
 271                         continue;
 272                 }
 273                 if (old_gr && !gr_equal(fgr, old_gr)) {
 274                         warnx("entry inconsistent");
 275                         free(fgr);
 276                         errno = EINVAL; /* hack */
 277                         goto err;
 278                 }
 279                 free(fgr);
 280
 281                 /* it is, replace or remove it */
 282                 if (line != NULL) {
 283                         len = strlen(line);
 284                         if (write(tfd, line, len) != (int) len)
 285                                 goto err;
 286                 } else {
 287                         /* when removed, avoid the \n */
 288                         q++;
 289                 }
 290                 /* we're done, just copy the rest over */
 291                 for (;;) {
 292                         if (write(tfd, q, end - q) != end - q)
 293                                 goto err;
 294                         q = buf;
 295                         readlen = read(ffd, buf, size);
 296                         if (readlen == 0)
 297                                 break;
 298                         else
 299                                 len = (size_t)readlen;
 300                         if (readlen == -1)
 301                                 goto err;
 302                         end = buf + len;
 303                 }
 304                 goto done;
 305         }
 306
 307         /* if we got here, we didn't find the old entry */
 308         if (line == NULL) {
 309                 errno = ENOENT;
 310                 goto err;
 311         }
 312         len = strlen(line);
 313         if ((size_t)write(tfd, line, len) != len ||
 314            write(tfd, "\n", 1) != 1)
 315                 goto err;
 316  done:
 317         free(line);
 318         free(buf);
 319         return (0);
 320  err:
 321         free(line);
 322         free(buf);
 323         return (-1);
 324 }
 325
 326 /*
 327  * Regenerate the group file
 328  */
 329 int
 330 gr_mkdb(void)
 331 {
 332         int fd;
 333
 334         if (chmod(tempname, 0644) != 0)
 335                 return (-1);
 336
 337         if (rename(tempname, group_file) != 0)
 338                 return (-1);
 339
 340         /*
 341          * Make sure new group file is safe on disk. To improve performance we
 342          * will call fsync() to the directory where file lies
 343          */
 344         if ((fd = open(group_dir, O_RDONLY|O_DIRECTORY)) == -1)
 345                 return (-1);
 346
 347         if (fsync(fd) != 0) {
 348                 close(fd);
 349                 return (-1);
 350         }
 351
 352         close(fd);
 353         return(0);
 354 }
 355
 356 /*
 357  * Clean up. Preserves errno for the caller's convenience.
 358  */
 359 void
 360 gr_fini(void)
 361 {
 362         int serrno;
 363
 364         if (!initialized)
 365                 return;
 366         initialized = 0;
 367         serrno = errno;
 368         if (*tempname != '\0') {
 369                 unlink(tempname);
 370                 *tempname = '\0';
 371         }
 372         if (lockfd != -1)
 373                 close(lockfd);
 374         errno = serrno;
 375 }
 376
 377 /*
 378  * Compares two struct group's.
 379  */
 380 int
 381 gr_equal(const struct group *gr1, const struct group *gr2)
 382 {
 383
 384         /* Check that the non-member information is the same. */
 385         if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
 386                 if (gr1->gr_name != gr2->gr_name)
 387                         return (false);
 388         } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
 389                 return (false);
 390         if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
 391                 if (gr1->gr_passwd != gr2->gr_passwd)
 392                         return (false);
 393         } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
 394                 return (false);
 395         if (gr1->gr_gid != gr2->gr_gid)
 396                 return (false);
 397
 398         /*
 399          * Check all members in both groups.
 400          * getgrnam can return gr_mem with a pointer to NULL.
 401          * gr_dup and gr_add strip out this superfluous NULL, setting
 402          * gr_mem to NULL for no members.
 403         */
 404         if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
 405                 int i;
 406
 407                 for (i = 0;
 408                     gr1->gr_mem[i] != NULL && gr2->gr_mem[i] != NULL; i++) {
 409                         if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
 410                                 return (false);
 411                 }
 412                 if (gr1->gr_mem[i] != NULL || gr2->gr_mem[i] != NULL)
 413                         return (false);
 414         } else if (gr1->gr_mem != NULL && gr1->gr_mem[0] != NULL) {
 415                 return (false);
 416         } else if (gr2->gr_mem != NULL && gr2->gr_mem[0] != NULL) {
 417                 return (false);
 418         }
 419
 420         return (true);
 421 }
 422
 423 /*
 424  * Make a group line out of a struct group.
 425  */
 426 char *
 427 gr_make(const struct group *gr)
 428 {
 429         const char *group_line_format = "%s:%s:%ju:";
 430         const char *sep;
 431         char *line;
 432         char *p;
 433         size_t line_size;
 434         int ndx;
 435
 436         /* Calculate the length of the group line. */
 437         line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
 438             gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
 439         if (gr->gr_mem != NULL) {
 440                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
 441                         line_size += strlen(gr->gr_mem[ndx]) + 1;
 442                 if (ndx > 0)
 443                         line_size--;
 444         }
 445
 446         /* Create the group line and fill it. */
 447         if ((line = p = malloc(line_size)) == NULL)
 448                 return (NULL);
 449         p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
 450             (uintmax_t)gr->gr_gid);
 451         if (gr->gr_mem != NULL) {
 452                 sep = "";
 453                 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
 454                         p = stpcpy(p, sep);
 455                         p = stpcpy(p, gr->gr_mem[ndx]);
 456                         sep = ",";
 457                 }
 458         }
 459
 460         return (line);
 461 }
 462
 463 /*
 464  * Duplicate a struct group.
 465  */
 466 struct group *
 467 gr_dup(const struct group *gr)
 468 {
 469         return (gr_add(gr, NULL));
 470 }
 471 /*
 472  * Add a new member name to a struct group.
 473  */
 474 struct group *
 475 gr_add(const struct group *gr, const char *newmember)
 476 {
 477         char *mem;
 478         size_t len;
 479         int num_mem;
 480
 481         num_mem = 0;
 482         len = grmemlen(gr, newmember, &num_mem);
 483         /* Create new group and copy old group into it. */
 484         if ((mem = malloc(len)) == NULL)
 485                 return (NULL);
 486         return (grcopy(gr, mem, newmember, num_mem));
 487 }
 488
 489 /* It is safer to walk the pointers given at gr_mem since there is no
 490  * guarantee the gr_mem + strings are contiguous in the given struct group
 491  * but compactify the new group into the following form.
 492  *
 493  * The new struct is laid out like this in memory. The example given is
 494  * for a group with two members only.
 495  *
 496  * {
 497  * (char *name)
 498  * (char *passwd)
 499  * (int gid)
 500  * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
 501  * gr_mem area
 502  * (member1 *)
 503  * (member2 *)
 504  * (NULL)
 505  * (name string)
 506  * (passwd string)
 507  * (member1 string)
 508  * (member2 string)
 509  * }
 510  */
 511 /*
 512  * Copy the contents of a group plus given name to a preallocated group struct
 513  */
 514 static struct group *
 515 grcopy(const struct group *gr, char *dst, const char *name, int ndx)
 516 {
 517         int i;
 518         struct group *newgr;
 519
 520         newgr = (struct group *)(void *)dst;    /* avoid alignment warning */
 521         dst += sizeof(*newgr);
 522         if (ndx != 0) {
 523                 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */
 524                 dst += (ndx + 1) * sizeof(*newgr->gr_mem);
 525         } else
 526                 newgr->gr_mem = NULL;
 527         if (gr->gr_name != NULL) {
 528                 newgr->gr_name = dst;
 529                 dst = stpcpy(dst, gr->gr_name) + 1;
 530         } else
 531                 newgr->gr_name = NULL;
 532         if (gr->gr_passwd != NULL) {
 533                 newgr->gr_passwd = dst;
 534                 dst = stpcpy(dst, gr->gr_passwd) + 1;
 535         } else
 536                 newgr->gr_passwd = NULL;
 537         newgr->gr_gid = gr->gr_gid;
 538         i = 0;
 539         /* Original group struct might have a NULL gr_mem */
 540         if (gr->gr_mem != NULL) {
 541                 for (; gr->gr_mem[i] != NULL; i++) {
 542                         newgr->gr_mem[i] = dst;
 543                         dst = stpcpy(dst, gr->gr_mem[i]) + 1;
 544                 }
 545         }
 546         /* If name is not NULL, newgr->gr_mem is known to be not NULL */
 547         if (name != NULL) {
 548                 newgr->gr_mem[i++] = dst;
 549                 dst = stpcpy(dst, name) + 1;
 550         }
 551         /* if newgr->gr_mem is not NULL add NULL marker */
 552         if (newgr->gr_mem != NULL)
 553                 newgr->gr_mem[i] = NULL;
 554
 555         return (newgr);
 556 }
 557
 558 /*
 559  *  Calculate length of a struct group + given name
 560  */
 561 static size_t
 562 grmemlen(const struct group *gr, const char *name, int *num_mem)
 563 {
 564         size_t len;
 565         int i;
 566
 567         if (gr == NULL)
 568                 return (0);
 569         /* Calculate size of the group. */
 570         len = sizeof(*gr);
 571         if (gr->gr_name != NULL)
 572                 len += strlen(gr->gr_name) + 1;
 573         if (gr->gr_passwd != NULL)
 574                 len += strlen(gr->gr_passwd) + 1;
 575         i = 0;
 576         if (gr->gr_mem != NULL) {
 577                 for (; gr->gr_mem[i] != NULL; i++) {
 578                         len += strlen(gr->gr_mem[i]) + 1;
 579                         len += sizeof(*gr->gr_mem);
 580                 }
 581         }
 582         if (name != NULL) {
 583                 i++;
 584                 len += strlen(name) + 1;
 585                 len += sizeof(*gr->gr_mem);
 586         }
 587         /* Allow for NULL pointer */
 588         if (i != 0)
 589                 len += sizeof(*gr->gr_mem);
 590         *num_mem = i;
 591         return(len);
 592 }
 593
 594 /*
 595  * Scan a line and place it into a group structure.
 596  */
 597 static bool
 598 __gr_scan(char *line, struct group *gr)
 599 {
 600         char *loc;
 601         int ndx;
 602
 603         /* Assign non-member information to structure. */
 604         gr->gr_name = line;
 605         if ((loc = strchr(line, ':')) == NULL)
 606                 return (false);
 607         *loc = '\0';
 608         gr->gr_passwd = loc + 1;
 609         if (*gr->gr_passwd == ':')
 610                 *gr->gr_passwd = '\0';
 611         else {
 612                 if ((loc = strchr(loc + 1, ':')) == NULL)
 613                         return (false);
 614                 *loc = '\0';
 615         }
 616         if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
 617                 return (false);
 618
 619         /* Assign member information to structure. */
 620         if ((loc = strchr(loc + 1, ':')) == NULL)
 621                 return (false);
 622         line = loc + 1;
 623         gr->gr_mem = NULL;
 624         ndx = 0;
 625         do {
 626                 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
 627                     (ndx + 1));
 628                 if (gr->gr_mem == NULL)
 629                         return (false);
 630
 631                 /* Skip locations without members (i.e., empty string). */
 632                 do {
 633                         gr->gr_mem[ndx] = strsep(&line, ",");
 634                 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
 635         } while (gr->gr_mem[ndx++] != NULL);
 636
 637         return (true);
 638 }
 639
 640 /*
 641  * Create a struct group from a line.
 642  */
 643 struct group *
 644 gr_scan(const char *line)
 645 {
 646         struct group gr;
 647         char *line_copy;
 648         struct group *new_gr;
 649
 650         if ((line_copy = strdup(line)) == NULL)
 651                 return (NULL);
 652         if (!__gr_scan(line_copy, &gr)) {
 653                 free(line_copy);
 654                 return (NULL);
 655         }
 656         new_gr = gr_dup(&gr);
 657         free(line_copy);
 658         if (gr.gr_mem != NULL)
 659                 free(gr.gr_mem);
 660
 661         return (new_gr);
 662 }