1 /*-- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 2002 Networks Associates Technology, Inc. 7 * All rights reserved. 8 * 9 * Portions of this software were developed for the FreeBSD Project by 10 * ThinkSec AS and NAI Labs, the Security Research Division of Network 11 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 12 * ("CBOSS"), as part of the DARPA CHATS research program. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 __FBSDID("$FreeBSD$"); 41 __SCCSID("@(#)pw_util.c 8.3 (Berkeley) 4/2/94"); 42 43 /* 44 * This file is used by all the "password" programs; vipw(8), chpass(1), 45 * and passwd(1). 46 */ 47 48 #include <sys/param.h> 49 #include <sys/errno.h> 50 #include <sys/time.h> 51 #include <sys/resource.h> 52 #include <sys/stat.h> 53 #include <sys/wait.h> 54 55 #include <ctype.h> 56 #include <err.h> 57 #include <fcntl.h> 58 #include <inttypes.h> 59 #include <paths.h> 60 #include <pwd.h> 61 #include <signal.h> 62 #include <stdio.h> 63 #include <stdlib.h> 64 #include <string.h> 65 #include <unistd.h> 66 67 #include "libutil.h" 68 69 static pid_t editpid = -1; 70 static int lockfd = -1; 71 static char masterpasswd[PATH_MAX]; 72 static char passwd_dir[PATH_MAX]; 73 static char tempname[PATH_MAX]; 74 static int initialized; 75 76 #if 0 77 void 78 pw_cont(int sig) 79 { 80 81 if (editpid != -1) 82 kill(editpid, sig); 83 } 84 #endif 85 86 /* 87 * Initialize statics and set limits, signals & umask to try to avoid 88 * interruptions, crashes etc. that might expose passord data. 89 */ 90 int 91 pw_init(const char *dir, const char *master) 92 { 93 #if 0 94 struct rlimit rlim; 95 #endif 96 97 if (dir == NULL) { 98 strcpy(passwd_dir, _PATH_ETC); 99 } else { 100 if (strlen(dir) >= sizeof(passwd_dir)) { 101 errno = ENAMETOOLONG; 102 return (-1); 103 } 104 strcpy(passwd_dir, dir); 105 } 106 107 if (master == NULL) { 108 if (dir == NULL) { 109 strcpy(masterpasswd, _PATH_MASTERPASSWD); 110 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s", 111 passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) { 112 errno = ENAMETOOLONG; 113 return (-1); 114 } 115 } else { 116 if (strlen(master) >= sizeof(masterpasswd)) { 117 errno = ENAMETOOLONG; 118 return (-1); 119 } 120 strcpy(masterpasswd, master); 121 } 122 123 /* 124 * The code that follows is extremely disruptive to the calling 125 * process, and is therefore disabled until someone can conceive 126 * of a realistic scenario where it would fend off a compromise. 127 * Race conditions concerning the temporary files can be guarded 128 * against in other ways than masking signals (by checking stat(2) 129 * results after creation). 130 */ 131 #if 0 132 /* Unlimited resource limits. */ 133 rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY; 134 (void)setrlimit(RLIMIT_CPU, &rlim); 135 (void)setrlimit(RLIMIT_FSIZE, &rlim); 136 (void)setrlimit(RLIMIT_STACK, &rlim); 137 (void)setrlimit(RLIMIT_DATA, &rlim); 138 (void)setrlimit(RLIMIT_RSS, &rlim); 139 140 /* Don't drop core (not really necessary, but GP's). */ 141 rlim.rlim_cur = rlim.rlim_max = 0; 142 (void)setrlimit(RLIMIT_CORE, &rlim); 143 144 /* Turn off signals. */ 145 (void)signal(SIGALRM, SIG_IGN); 146 (void)signal(SIGHUP, SIG_IGN); 147 (void)signal(SIGINT, SIG_IGN); 148 (void)signal(SIGPIPE, SIG_IGN); 149 (void)signal(SIGQUIT, SIG_IGN); 150 (void)signal(SIGTERM, SIG_IGN); 151 (void)signal(SIGCONT, pw_cont); 152 153 /* Create with exact permissions. */ 154 (void)umask(0); 155 #endif 156 initialized = 1; 157 return (0); 158 } 159 160 /* 161 * Lock the master password file. 162 */ 163 int 164 pw_lock(void) 165 { 166 167 if (*masterpasswd == '\0') 168 return (-1); 169 170 /* 171 * If the master password file doesn't exist, the system is hosed. 172 * Might as well try to build one. Set the close-on-exec bit so 173 * that users can't get at the encrypted passwords while editing. 174 * Open should allow flock'ing the file; see 4.4BSD. XXX 175 */ 176 for (;;) { 177 struct stat st; 178 179 lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0); 180 if (lockfd == -1) { 181 if (errno == EWOULDBLOCK) { 182 errx(1, "the password db file is busy"); 183 } else { 184 err(1, "could not lock the passwd file"); 185 } 186 } 187 188 /* 189 * If the password file was replaced while we were trying to 190 * get the lock, our hardlink count will be 0 and we have to 191 * close and retry. 192 */ 193 if (fstat(lockfd, &st) == -1) 194 err(1, "fstat() failed"); 195 if (st.st_nlink != 0) 196 break; 197 close(lockfd); 198 lockfd = -1; 199 } 200 return (lockfd); 201 } 202 203 /* 204 * Create and open a presumably safe temp file for editing the password 205 * data, and copy the master password file into it. 206 */ 207 int 208 pw_tmp(int mfd) 209 { 210 char buf[8192]; 211 ssize_t nr; 212 const char *p; 213 int tfd; 214 215 if (*masterpasswd == '\0') 216 return (-1); 217 if ((p = strrchr(masterpasswd, '/'))) 218 ++p; 219 else 220 p = masterpasswd; 221 if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX", 222 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) { 223 errno = ENAMETOOLONG; 224 return (-1); 225 } 226 if ((tfd = mkostemp(tempname, 0)) == -1) 227 return (-1); 228 if (mfd != -1) { 229 while ((nr = read(mfd, buf, sizeof(buf))) > 0) 230 if (write(tfd, buf, (size_t)nr) != nr) 231 break; 232 if (nr != 0) { 233 unlink(tempname); 234 *tempname = '\0'; 235 close(tfd); 236 return (-1); 237 } 238 } 239 return (tfd); 240 } 241 242 /* 243 * Regenerate the password database. 244 */ 245 int 246 pw_mkdb(const char *user) 247 { 248 int pstat; 249 pid_t pid; 250 251 (void)fflush(stderr); 252 switch ((pid = fork())) { 253 case -1: 254 return (-1); 255 case 0: 256 /* child */ 257 if (user == NULL) 258 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 259 "-d", passwd_dir, tempname, (char *)NULL); 260 else 261 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 262 "-d", passwd_dir, "-u", user, tempname, 263 (char *)NULL); 264 _exit(1); 265 /* NOTREACHED */ 266 default: 267 /* parent */ 268 break; 269 } 270 if (waitpid(pid, &pstat, 0) == -1) 271 return (-1); 272 if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) 273 return (0); 274 errno = 0; 275 return (-1); 276 } 277 278 /* 279 * Edit the temp file. Return -1 on error, >0 if the file was modified, 0 280 * if it was not. 281 */ 282 int 283 pw_edit(int notsetuid) 284 { 285 struct sigaction sa, sa_int, sa_quit; 286 sigset_t oldsigset, nsigset; 287 struct stat st1, st2; 288 const char *editor; 289 int pstat; 290 291 if ((editor = getenv("EDITOR")) == NULL) 292 editor = _PATH_VI; 293 if (stat(tempname, &st1) == -1) 294 return (-1); 295 sa.sa_handler = SIG_IGN; 296 sigemptyset(&sa.sa_mask); 297 sa.sa_flags = 0; 298 sigaction(SIGINT, &sa, &sa_int); 299 sigaction(SIGQUIT, &sa, &sa_quit); 300 sigemptyset(&nsigset); 301 sigaddset(&nsigset, SIGCHLD); 302 sigprocmask(SIG_BLOCK, &nsigset, &oldsigset); 303 switch ((editpid = fork())) { 304 case -1: 305 return (-1); 306 case 0: 307 sigaction(SIGINT, &sa_int, NULL); 308 sigaction(SIGQUIT, &sa_quit, NULL); 309 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 310 if (notsetuid) { 311 if (setgid(getgid()) == -1) 312 err(1, "setgid"); 313 if (setuid(getuid()) == -1) 314 err(1, "setuid"); 315 } 316 execlp(editor, editor, tempname, (char *)NULL); 317 err(1, "%s", editor); 318 default: 319 /* parent */ 320 break; 321 } 322 for (;;) { 323 if (waitpid(editpid, &pstat, WUNTRACED) == -1) { 324 if (errno == EINTR) 325 continue; 326 unlink(tempname); 327 editpid = -1; 328 break; 329 } else if (WIFSTOPPED(pstat)) { 330 raise(WSTOPSIG(pstat)); 331 } else if (WIFEXITED(pstat)) { 332 if (WEXITSTATUS(pstat) != 0) 333 errx(1, "\"%s\" exited with status %d", editor, WEXITSTATUS(pstat)); 334 editpid = -1; 335 break; 336 } else { 337 unlink(tempname); 338 editpid = -1; 339 break; 340 } 341 } 342 sigaction(SIGINT, &sa_int, NULL); 343 sigaction(SIGQUIT, &sa_quit, NULL); 344 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 345 if (stat(tempname, &st2) == -1) 346 return (-1); 347 return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec || 348 st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec); 349 } 350 351 /* 352 * Clean up. Preserve errno for the caller's convenience. 353 */ 354 void 355 pw_fini(void) 356 { 357 int serrno, status; 358 359 if (!initialized) 360 return; 361 initialized = 0; 362 serrno = errno; 363 if (editpid != -1) { 364 kill(editpid, SIGTERM); 365 kill(editpid, SIGCONT); 366 waitpid(editpid, &status, 0); 367 editpid = -1; 368 } 369 if (*tempname != '\0') { 370 unlink(tempname); 371 *tempname = '\0'; 372 } 373 if (lockfd != -1) 374 close(lockfd); 375 errno = serrno; 376 } 377 378 /* 379 * Compares two struct pwds. 380 */ 381 int 382 pw_equal(const struct passwd *pw1, const struct passwd *pw2) 383 { 384 return (strcmp(pw1->pw_name, pw2->pw_name) == 0 && 385 pw1->pw_uid == pw2->pw_uid && 386 pw1->pw_gid == pw2->pw_gid && 387 strcmp(pw1->pw_class, pw2->pw_class) == 0 && 388 pw1->pw_change == pw2->pw_change && 389 pw1->pw_expire == pw2->pw_expire && 390 strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 && 391 strcmp(pw1->pw_dir, pw2->pw_dir) == 0 && 392 strcmp(pw1->pw_shell, pw2->pw_shell) == 0); 393 } 394 395 /* 396 * Make a passwd line out of a struct passwd. 397 */ 398 char * 399 pw_make(const struct passwd *pw) 400 { 401 char *line; 402 403 asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name, 404 pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid, 405 pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire, 406 pw->pw_gecos, pw->pw_dir, pw->pw_shell); 407 return (line); 408 } 409 410 /* 411 * Make a passwd line (in v7 format) out of a struct passwd 412 */ 413 char * 414 pw_make_v7(const struct passwd *pw) 415 { 416 char *line; 417 418 asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name, 419 (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid, 420 pw->pw_gecos, pw->pw_dir, pw->pw_shell); 421 return (line); 422 } 423 424 /* 425 * Copy password file from one descriptor to another, replacing, deleting 426 * or adding a single record on the way. 427 */ 428 int 429 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw) 430 { 431 char *buf, *end, *line, *p, *q, *r, *tmp; 432 struct passwd *fpw; 433 const struct passwd *spw; 434 size_t len, size; 435 int eof, readlen; 436 char t; 437 438 if (old_pw == NULL && pw == NULL) 439 return (-1); 440 441 spw = old_pw; 442 /* deleting a user */ 443 if (pw == NULL) { 444 line = NULL; 445 } else { 446 if ((line = pw_make(pw)) == NULL) 447 return (-1); 448 } 449 450 /* adding a user */ 451 if (spw == NULL) 452 spw = pw; 453 454 /* initialize the buffer */ 455 if ((buf = malloc(size = 1024)) == NULL) 456 goto err; 457 458 eof = 0; 459 len = 0; 460 p = q = end = buf; 461 for (;;) { 462 /* find the end of the current line */ 463 for (p = q; q < end && *q != '\0'; ++q) 464 if (*q == '\n') 465 break; 466 467 /* if we don't have a complete line, fill up the buffer */ 468 if (q >= end) { 469 if (eof) 470 break; 471 while ((size_t)(q - p) >= size) { 472 if ((tmp = reallocarray(buf, 2, size)) == NULL) { 473 warnx("passwd line too long"); 474 goto err; 475 } 476 p = tmp + (p - buf); 477 q = tmp + (q - buf); 478 end = tmp + (end - buf); 479 buf = tmp; 480 size = size * 2; 481 } 482 if (p < end) { 483 q = memmove(buf, p, end - p); 484 end -= p - buf; 485 } else { 486 p = q = end = buf; 487 } 488 readlen = read(ffd, end, size - (end - buf)); 489 if (readlen == -1) 490 goto err; 491 else 492 len = (size_t)readlen; 493 if (len == 0 && p == buf) 494 break; 495 end += len; 496 len = end - buf; 497 if (len < size) { 498 eof = 1; 499 if (len > 0 && buf[len - 1] != '\n') 500 ++len, *end++ = '\n'; 501 } 502 continue; 503 } 504 505 /* is it a blank line or a comment? */ 506 for (r = p; r < q && isspace(*r); ++r) 507 /* nothing */ ; 508 if (r == q || *r == '#') { 509 /* yep */ 510 if (write(tfd, p, q - p + 1) != q - p + 1) 511 goto err; 512 ++q; 513 continue; 514 } 515 516 /* is it the one we're looking for? */ 517 518 t = *q; 519 *q = '\0'; 520 521 fpw = pw_scan(r, PWSCAN_MASTER); 522 523 /* 524 * fpw is either the struct passwd for the current line, 525 * or NULL if the line is malformed. 526 */ 527 528 *q = t; 529 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) { 530 /* nope */ 531 if (fpw != NULL) 532 free(fpw); 533 if (write(tfd, p, q - p + 1) != q - p + 1) 534 goto err; 535 ++q; 536 continue; 537 } 538 if (old_pw && !pw_equal(fpw, old_pw)) { 539 warnx("entry inconsistent"); 540 free(fpw); 541 errno = EINVAL; /* hack */ 542 goto err; 543 } 544 free(fpw); 545 546 /* it is, replace or remove it */ 547 if (line != NULL) { 548 len = strlen(line); 549 if (write(tfd, line, len) != (int)len) 550 goto err; 551 } else { 552 /* when removed, avoid the \n */ 553 q++; 554 } 555 /* we're done, just copy the rest over */ 556 for (;;) { 557 if (write(tfd, q, end - q) != end - q) 558 goto err; 559 q = buf; 560 readlen = read(ffd, buf, size); 561 if (readlen == 0) 562 break; 563 else 564 len = (size_t)readlen; 565 if (readlen == -1) 566 goto err; 567 end = buf + len; 568 } 569 goto done; 570 } 571 572 /* if we got here, we didn't find the old entry */ 573 if (line == NULL) { 574 errno = ENOENT; 575 goto err; 576 } 577 len = strlen(line); 578 if ((size_t)write(tfd, line, len) != len || 579 write(tfd, "\n", 1) != 1) 580 goto err; 581 done: 582 free(line); 583 free(buf); 584 return (0); 585 err: 586 free(line); 587 free(buf); 588 return (-1); 589 } 590 591 /* 592 * Return the current value of tempname. 593 */ 594 const char * 595 pw_tempname(void) 596 { 597 598 return (tempname); 599 } 600 601 /* 602 * Duplicate a struct passwd. 603 */ 604 struct passwd * 605 pw_dup(const struct passwd *pw) 606 { 607 char *dst; 608 struct passwd *npw; 609 ssize_t len; 610 611 len = sizeof(*npw); 612 if (pw->pw_name != NULL) 613 len += strlen(pw->pw_name) + 1; 614 if (pw->pw_passwd != NULL) 615 len += strlen(pw->pw_passwd) + 1; 616 if (pw->pw_class != NULL) 617 len += strlen(pw->pw_class) + 1; 618 if (pw->pw_gecos != NULL) 619 len += strlen(pw->pw_gecos) + 1; 620 if (pw->pw_dir != NULL) 621 len += strlen(pw->pw_dir) + 1; 622 if (pw->pw_shell != NULL) 623 len += strlen(pw->pw_shell) + 1; 624 if ((npw = malloc((size_t)len)) == NULL) 625 return (NULL); 626 memcpy(npw, pw, sizeof(*npw)); 627 dst = (char *)npw + sizeof(*npw); 628 if (pw->pw_name != NULL) { 629 npw->pw_name = dst; 630 dst = stpcpy(npw->pw_name, pw->pw_name) + 1; 631 } 632 if (pw->pw_passwd != NULL) { 633 npw->pw_passwd = dst; 634 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1; 635 } 636 if (pw->pw_class != NULL) { 637 npw->pw_class = dst; 638 dst = stpcpy(npw->pw_class, pw->pw_class) + 1; 639 } 640 if (pw->pw_gecos != NULL) { 641 npw->pw_gecos = dst; 642 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1; 643 } 644 if (pw->pw_dir != NULL) { 645 npw->pw_dir = dst; 646 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1; 647 } 648 if (pw->pw_shell != NULL) { 649 npw->pw_shell = dst; 650 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1; 651 } 652 return (npw); 653 } 654 655 #include "pw_scan.h" 656 657 /* 658 * Wrapper around some internal libc functions. 659 */ 660 661 void 662 pw_initpwd(struct passwd *pw) 663 { 664 665 __pw_initpwd(pw); 666 } 667 668 struct passwd * 669 pw_scan(const char *line, int flags) 670 { 671 struct passwd pw, *ret; 672 char *bp; 673 674 if ((bp = strdup(line)) == NULL) 675 return (NULL); 676 __pw_initpwd(&pw); 677 if (!__pw_scan(bp, &pw, flags)) { 678 free(bp); 679 return (NULL); 680 } 681 ret = pw_dup(&pw); 682 free(bp); 683 return (ret); 684 } 685