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 int gr1_ndx; 355 int gr2_ndx; 356 357 /* Check that the non-member information is the same. */ 358 if (gr1->gr_name == NULL || gr2->gr_name == NULL) { 359 if (gr1->gr_name != gr2->gr_name) 360 return (false); 361 } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0) 362 return (false); 363 if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) { 364 if (gr1->gr_passwd != gr2->gr_passwd) 365 return (false); 366 } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0) 367 return (false); 368 if (gr1->gr_gid != gr2->gr_gid) 369 return (false); 370 371 /* Check all members in both groups. 372 * getgrnam can return gr_mem with a pointer to NULL. 373 * gr_dup and gr_add strip out this superfluous NULL, setting 374 * gr_mem to NULL for no members. 375 */ 376 if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) { 377 int i; 378 379 for (i = 0; gr1->gr_mem[i] != NULL; i++) { 380 if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0) 381 return (false); 382 } 383 } 384 /* Count number of members in both structs */ 385 gr2_ndx = 0; 386 if (gr2->gr_mem != NULL) 387 for(; gr2->gr_mem[gr2_ndx] != NULL; gr2_ndx++) 388 /* empty */; 389 gr1_ndx = 0; 390 if (gr1->gr_mem != NULL) 391 for(; gr1->gr_mem[gr1_ndx] != NULL; gr1_ndx++) 392 /* empty */; 393 if (gr1_ndx != gr2_ndx) 394 return (false); 395 396 return (true); 397 } 398 399 /* 400 * Make a group line out of a struct group. 401 */ 402 char * 403 gr_make(const struct group *gr) 404 { 405 const char *group_line_format = "%s:%s:%ju:"; 406 const char *sep; 407 char *line; 408 char *p; 409 size_t line_size; 410 int ndx; 411 412 /* Calculate the length of the group line. */ 413 line_size = snprintf(NULL, 0, group_line_format, gr->gr_name, 414 gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1; 415 if (gr->gr_mem != NULL) { 416 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) 417 line_size += strlen(gr->gr_mem[ndx]) + 1; 418 if (ndx > 0) 419 line_size--; 420 } 421 422 /* Create the group line and fill it. */ 423 if ((line = p = malloc(line_size)) == NULL) 424 return (NULL); 425 p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd, 426 (uintmax_t)gr->gr_gid); 427 if (gr->gr_mem != NULL) { 428 sep = ""; 429 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) { 430 p = stpcpy(p, sep); 431 p = stpcpy(p, gr->gr_mem[ndx]); 432 sep = ","; 433 } 434 } 435 436 return (line); 437 } 438 439 /* 440 * Duplicate a struct group. 441 */ 442 struct group * 443 gr_dup(const struct group *gr) 444 { 445 return (gr_add(gr, NULL)); 446 } 447 /* 448 * Add a new member name to a struct group. 449 */ 450 struct group * 451 gr_add(const struct group *gr, const char *newmember) 452 { 453 char *mem; 454 size_t len; 455 int num_mem; 456 457 num_mem = 0; 458 len = grmemlen(gr, newmember, &num_mem); 459 /* Create new group and copy old group into it. */ 460 if ((mem = malloc(len)) == NULL) 461 return (NULL); 462 return (grcopy(gr, mem, newmember, num_mem)); 463 } 464 465 /* It is safer to walk the pointers given at gr_mem since there is no 466 * guarantee the gr_mem + strings are contiguous in the given struct group 467 * but compactify the new group into the following form. 468 * 469 * The new struct is laid out like this in memory. The example given is 470 * for a group with two members only. 471 * 472 * { 473 * (char *name) 474 * (char *passwd) 475 * (int gid) 476 * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area 477 * gr_mem area 478 * (member1 *) 479 * (member2 *) 480 * (NULL) 481 * (name string) 482 * (passwd string) 483 * (member1 string) 484 * (member2 string) 485 * } 486 */ 487 /* 488 * Copy the contents of a group plus given name to a preallocated group struct 489 */ 490 static struct group * 491 grcopy(const struct group *gr, char *dst, const char *name, int ndx) 492 { 493 int i; 494 struct group *newgr; 495 496 newgr = (struct group *)(void *)dst; /* avoid alignment warning */ 497 dst += sizeof(*newgr); 498 if (ndx != 0) { 499 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */ 500 dst += (ndx + 1) * sizeof(*newgr->gr_mem); 501 } else 502 newgr->gr_mem = NULL; 503 if (gr->gr_name != NULL) { 504 newgr->gr_name = dst; 505 dst = stpcpy(dst, gr->gr_name) + 1; 506 } else 507 newgr->gr_name = NULL; 508 if (gr->gr_passwd != NULL) { 509 newgr->gr_passwd = dst; 510 dst = stpcpy(dst, gr->gr_passwd) + 1; 511 } else 512 newgr->gr_passwd = NULL; 513 newgr->gr_gid = gr->gr_gid; 514 i = 0; 515 /* Original group struct might have a NULL gr_mem */ 516 if (gr->gr_mem != NULL) { 517 for (; gr->gr_mem[i] != NULL; i++) { 518 newgr->gr_mem[i] = dst; 519 dst = stpcpy(dst, gr->gr_mem[i]) + 1; 520 } 521 } 522 /* If name is not NULL, newgr->gr_mem is known to be not NULL */ 523 if (name != NULL) { 524 newgr->gr_mem[i++] = dst; 525 dst = stpcpy(dst, name) + 1; 526 } 527 /* if newgr->gr_mem is not NULL add NULL marker */ 528 if (newgr->gr_mem != NULL) 529 newgr->gr_mem[i] = NULL; 530 531 return (newgr); 532 } 533 534 /* 535 * Calculate length of a struct group + given name 536 */ 537 static size_t 538 grmemlen(const struct group *gr, const char *name, int *num_mem) 539 { 540 size_t len; 541 int i; 542 543 if (gr == NULL) 544 return (0); 545 /* Calculate size of the group. */ 546 len = sizeof(*gr); 547 if (gr->gr_name != NULL) 548 len += strlen(gr->gr_name) + 1; 549 if (gr->gr_passwd != NULL) 550 len += strlen(gr->gr_passwd) + 1; 551 i = 0; 552 if (gr->gr_mem != NULL) { 553 for (; gr->gr_mem[i] != NULL; i++) { 554 len += strlen(gr->gr_mem[i]) + 1; 555 len += sizeof(*gr->gr_mem); 556 } 557 } 558 if (name != NULL) { 559 i++; 560 len += strlen(name) + 1; 561 len += sizeof(*gr->gr_mem); 562 } 563 /* Allow for NULL pointer */ 564 if (i != 0) 565 len += sizeof(*gr->gr_mem); 566 *num_mem = i; 567 return(len); 568 } 569 570 /* 571 * Scan a line and place it into a group structure. 572 */ 573 static bool 574 __gr_scan(char *line, struct group *gr) 575 { 576 char *loc; 577 int ndx; 578 579 /* Assign non-member information to structure. */ 580 gr->gr_name = line; 581 if ((loc = strchr(line, ':')) == NULL) 582 return (false); 583 *loc = '\0'; 584 gr->gr_passwd = loc + 1; 585 if (*gr->gr_passwd == ':') 586 *gr->gr_passwd = '\0'; 587 else { 588 if ((loc = strchr(loc + 1, ':')) == NULL) 589 return (false); 590 *loc = '\0'; 591 } 592 if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1) 593 return (false); 594 595 /* Assign member information to structure. */ 596 if ((loc = strchr(loc + 1, ':')) == NULL) 597 return (false); 598 line = loc + 1; 599 gr->gr_mem = NULL; 600 ndx = 0; 601 do { 602 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) * 603 (ndx + 1)); 604 if (gr->gr_mem == NULL) 605 return (false); 606 607 /* Skip locations without members (i.e., empty string). */ 608 do { 609 gr->gr_mem[ndx] = strsep(&line, ","); 610 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0'); 611 } while (gr->gr_mem[ndx++] != NULL); 612 613 return (true); 614 } 615 616 /* 617 * Create a struct group from a line. 618 */ 619 struct group * 620 gr_scan(const char *line) 621 { 622 struct group gr; 623 char *line_copy; 624 struct group *new_gr; 625 626 if ((line_copy = strdup(line)) == NULL) 627 return (NULL); 628 if (!__gr_scan(line_copy, &gr)) { 629 free(line_copy); 630 return (NULL); 631 } 632 new_gr = gr_dup(&gr); 633 free(line_copy); 634 if (gr.gr_mem != NULL) 635 free(gr.gr_mem); 636 637 return (new_gr); 638 } 639