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