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