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, O_SYNC)) == -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 int fd; 322 323 if (chmod(tempname, 0644) != 0) 324 return (-1); 325 326 if (rename(tempname, group_file) != 0) 327 return (-1); 328 329 /* 330 * Make sure new group file is safe on disk. To improve performance we 331 * will call fsync() to the directory where file lies 332 */ 333 if ((fd = open(group_dir, O_RDONLY|O_DIRECTORY)) == -1) 334 return (-1); 335 336 if (fsync(fd) != 0) { 337 close(fd); 338 return (-1); 339 } 340 341 close(fd); 342 return(0); 343 } 344 345 /* 346 * Clean up. Preserves errno for the caller's convenience. 347 */ 348 void 349 gr_fini(void) 350 { 351 int serrno; 352 353 if (!initialized) 354 return; 355 initialized = 0; 356 serrno = errno; 357 if (*tempname != '\0') { 358 unlink(tempname); 359 *tempname = '\0'; 360 } 361 if (lockfd != -1) 362 close(lockfd); 363 errno = serrno; 364 } 365 366 /* 367 * Compares two struct group's. 368 */ 369 int 370 gr_equal(const struct group *gr1, const struct group *gr2) 371 { 372 373 /* Check that the non-member information is the same. */ 374 if (gr1->gr_name == NULL || gr2->gr_name == NULL) { 375 if (gr1->gr_name != gr2->gr_name) 376 return (false); 377 } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0) 378 return (false); 379 if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) { 380 if (gr1->gr_passwd != gr2->gr_passwd) 381 return (false); 382 } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0) 383 return (false); 384 if (gr1->gr_gid != gr2->gr_gid) 385 return (false); 386 387 /* 388 * Check all members in both groups. 389 * getgrnam can return gr_mem with a pointer to NULL. 390 * gr_dup and gr_add strip out this superfluous NULL, setting 391 * gr_mem to NULL for no members. 392 */ 393 if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) { 394 int i; 395 396 for (i = 0; 397 gr1->gr_mem[i] != NULL && gr2->gr_mem[i] != NULL; i++) { 398 if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0) 399 return (false); 400 } 401 if (gr1->gr_mem[i] != NULL || gr2->gr_mem[i] != NULL) 402 return (false); 403 } else if (gr1->gr_mem != NULL && gr1->gr_mem[0] != NULL) { 404 return (false); 405 } else if (gr2->gr_mem != NULL && gr2->gr_mem[0] != NULL) { 406 return (false); 407 } 408 409 return (true); 410 } 411 412 /* 413 * Make a group line out of a struct group. 414 */ 415 char * 416 gr_make(const struct group *gr) 417 { 418 const char *group_line_format = "%s:%s:%ju:"; 419 const char *sep; 420 char *line; 421 char *p; 422 size_t line_size; 423 int ndx; 424 425 /* Calculate the length of the group line. */ 426 line_size = snprintf(NULL, 0, group_line_format, gr->gr_name, 427 gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1; 428 if (gr->gr_mem != NULL) { 429 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) 430 line_size += strlen(gr->gr_mem[ndx]) + 1; 431 if (ndx > 0) 432 line_size--; 433 } 434 435 /* Create the group line and fill it. */ 436 if ((line = p = malloc(line_size)) == NULL) 437 return (NULL); 438 p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd, 439 (uintmax_t)gr->gr_gid); 440 if (gr->gr_mem != NULL) { 441 sep = ""; 442 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) { 443 p = stpcpy(p, sep); 444 p = stpcpy(p, gr->gr_mem[ndx]); 445 sep = ","; 446 } 447 } 448 449 return (line); 450 } 451 452 /* 453 * Duplicate a struct group. 454 */ 455 struct group * 456 gr_dup(const struct group *gr) 457 { 458 return (gr_add(gr, NULL)); 459 } 460 /* 461 * Add a new member name to a struct group. 462 */ 463 struct group * 464 gr_add(const struct group *gr, const char *newmember) 465 { 466 char *mem; 467 size_t len; 468 int num_mem; 469 470 num_mem = 0; 471 len = grmemlen(gr, newmember, &num_mem); 472 /* Create new group and copy old group into it. */ 473 if ((mem = malloc(len)) == NULL) 474 return (NULL); 475 return (grcopy(gr, mem, newmember, num_mem)); 476 } 477 478 /* It is safer to walk the pointers given at gr_mem since there is no 479 * guarantee the gr_mem + strings are contiguous in the given struct group 480 * but compactify the new group into the following form. 481 * 482 * The new struct is laid out like this in memory. The example given is 483 * for a group with two members only. 484 * 485 * { 486 * (char *name) 487 * (char *passwd) 488 * (int gid) 489 * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area 490 * gr_mem area 491 * (member1 *) 492 * (member2 *) 493 * (NULL) 494 * (name string) 495 * (passwd string) 496 * (member1 string) 497 * (member2 string) 498 * } 499 */ 500 /* 501 * Copy the contents of a group plus given name to a preallocated group struct 502 */ 503 static struct group * 504 grcopy(const struct group *gr, char *dst, const char *name, int ndx) 505 { 506 int i; 507 struct group *newgr; 508 509 newgr = (struct group *)(void *)dst; /* avoid alignment warning */ 510 dst += sizeof(*newgr); 511 if (ndx != 0) { 512 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */ 513 dst += (ndx + 1) * sizeof(*newgr->gr_mem); 514 } else 515 newgr->gr_mem = NULL; 516 if (gr->gr_name != NULL) { 517 newgr->gr_name = dst; 518 dst = stpcpy(dst, gr->gr_name) + 1; 519 } else 520 newgr->gr_name = NULL; 521 if (gr->gr_passwd != NULL) { 522 newgr->gr_passwd = dst; 523 dst = stpcpy(dst, gr->gr_passwd) + 1; 524 } else 525 newgr->gr_passwd = NULL; 526 newgr->gr_gid = gr->gr_gid; 527 i = 0; 528 /* Original group struct might have a NULL gr_mem */ 529 if (gr->gr_mem != NULL) { 530 for (; gr->gr_mem[i] != NULL; i++) { 531 newgr->gr_mem[i] = dst; 532 dst = stpcpy(dst, gr->gr_mem[i]) + 1; 533 } 534 } 535 /* If name is not NULL, newgr->gr_mem is known to be not NULL */ 536 if (name != NULL) { 537 newgr->gr_mem[i++] = dst; 538 dst = stpcpy(dst, name) + 1; 539 } 540 /* if newgr->gr_mem is not NULL add NULL marker */ 541 if (newgr->gr_mem != NULL) 542 newgr->gr_mem[i] = NULL; 543 544 return (newgr); 545 } 546 547 /* 548 * Calculate length of a struct group + given name 549 */ 550 static size_t 551 grmemlen(const struct group *gr, const char *name, int *num_mem) 552 { 553 size_t len; 554 int i; 555 556 if (gr == NULL) 557 return (0); 558 /* Calculate size of the group. */ 559 len = sizeof(*gr); 560 if (gr->gr_name != NULL) 561 len += strlen(gr->gr_name) + 1; 562 if (gr->gr_passwd != NULL) 563 len += strlen(gr->gr_passwd) + 1; 564 i = 0; 565 if (gr->gr_mem != NULL) { 566 for (; gr->gr_mem[i] != NULL; i++) { 567 len += strlen(gr->gr_mem[i]) + 1; 568 len += sizeof(*gr->gr_mem); 569 } 570 } 571 if (name != NULL) { 572 i++; 573 len += strlen(name) + 1; 574 len += sizeof(*gr->gr_mem); 575 } 576 /* Allow for NULL pointer */ 577 if (i != 0) 578 len += sizeof(*gr->gr_mem); 579 *num_mem = i; 580 return(len); 581 } 582 583 /* 584 * Scan a line and place it into a group structure. 585 */ 586 static bool 587 __gr_scan(char *line, struct group *gr) 588 { 589 char *loc; 590 int ndx; 591 592 /* Assign non-member information to structure. */ 593 gr->gr_name = line; 594 if ((loc = strchr(line, ':')) == NULL) 595 return (false); 596 *loc = '\0'; 597 gr->gr_passwd = loc + 1; 598 if (*gr->gr_passwd == ':') 599 *gr->gr_passwd = '\0'; 600 else { 601 if ((loc = strchr(loc + 1, ':')) == NULL) 602 return (false); 603 *loc = '\0'; 604 } 605 if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1) 606 return (false); 607 608 /* Assign member information to structure. */ 609 if ((loc = strchr(loc + 1, ':')) == NULL) 610 return (false); 611 line = loc + 1; 612 gr->gr_mem = NULL; 613 ndx = 0; 614 do { 615 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) * 616 (ndx + 1)); 617 if (gr->gr_mem == NULL) 618 return (false); 619 620 /* Skip locations without members (i.e., empty string). */ 621 do { 622 gr->gr_mem[ndx] = strsep(&line, ","); 623 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0'); 624 } while (gr->gr_mem[ndx++] != NULL); 625 626 return (true); 627 } 628 629 /* 630 * Create a struct group from a line. 631 */ 632 struct group * 633 gr_scan(const char *line) 634 { 635 struct group gr; 636 char *line_copy; 637 struct group *new_gr; 638 639 if ((line_copy = strdup(line)) == NULL) 640 return (NULL); 641 if (!__gr_scan(line_copy, &gr)) { 642 free(line_copy); 643 return (NULL); 644 } 645 new_gr = gr_dup(&gr); 646 free(line_copy); 647 if (gr.gr_mem != NULL) 648 free(gr.gr_mem); 649 650 return (new_gr); 651 } 652