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