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 * $FreeBSD: src/lib/libutil/pw_util.c,v 1.35 2004/05/18 15:53:58 stefanf Exp $ 41 * $DragonFly: src/lib/libutil/pw_util.c,v 1.1 2005/08/01 16:13:20 joerg Exp $ 42 */ 43 44 /* 45 * This file is used by all the "password" programs; vipw(8), chpass(1), 46 * and passwd(1). 47 */ 48 49 #include <sys/param.h> 50 #include <sys/errno.h> 51 #include <sys/time.h> 52 #include <sys/resource.h> 53 #include <sys/stat.h> 54 #include <sys/wait.h> 55 56 #include <ctype.h> 57 #include <err.h> 58 #include <fcntl.h> 59 #include <inttypes.h> 60 #include <libgen.h> 61 #include <paths.h> 62 #include <pwd.h> 63 #include <signal.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <string.h> 67 #include <unistd.h> 68 69 #include <libutil.h> 70 71 static pid_t editpid = -1; 72 static int lockfd = -1; 73 static char masterpasswd[PATH_MAX]; 74 static char passwd_dir[PATH_MAX]; 75 static char tempname[PATH_MAX]; 76 static int initialized; 77 78 #if 0 79 void 80 pw_cont(int sig) 81 { 82 83 if (editpid != -1) 84 kill(editpid, sig); 85 } 86 #endif 87 88 /* 89 * Initialize statics and set limits, signals & umask to try to avoid 90 * interruptions, crashes etc. that might expose passord data. 91 */ 92 int 93 pw_init(const char *dir, const char *master) 94 { 95 #if 0 96 struct rlimit rlim; 97 #endif 98 99 if (dir == NULL) { 100 strcpy(passwd_dir, _PATH_ETC); 101 } else { 102 if (strlen(dir) >= sizeof(passwd_dir)) { 103 errno = ENAMETOOLONG; 104 return (-1); 105 } 106 strcpy(passwd_dir, dir); 107 } 108 109 if (master == NULL) { 110 if (dir == NULL) { 111 strcpy(masterpasswd, _PATH_MASTERPASSWD); 112 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s", 113 passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) { 114 errno = ENAMETOOLONG; 115 return (-1); 116 } 117 } else { 118 if (strlen(master) >= sizeof(masterpasswd)) { 119 errno = ENAMETOOLONG; 120 return (-1); 121 } 122 strcpy(masterpasswd, master); 123 } 124 125 /* 126 * The code that follows is extremely disruptive to the calling 127 * process, and is therefore disabled until someone can conceive 128 * of a realistic scenario where it would fend off a compromise. 129 * Race conditions concerning the temporary files can be guarded 130 * against in other ways than masking signals (by checking stat(2) 131 * results after creation). 132 */ 133 #if 0 134 /* Unlimited resource limits. */ 135 rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY; 136 (void)setrlimit(RLIMIT_CPU, &rlim); 137 (void)setrlimit(RLIMIT_FSIZE, &rlim); 138 (void)setrlimit(RLIMIT_STACK, &rlim); 139 (void)setrlimit(RLIMIT_DATA, &rlim); 140 (void)setrlimit(RLIMIT_RSS, &rlim); 141 142 /* Don't drop core (not really necessary, but GP's). */ 143 rlim.rlim_cur = rlim.rlim_max = 0; 144 (void)setrlimit(RLIMIT_CORE, &rlim); 145 146 /* Turn off signals. */ 147 (void)signal(SIGALRM, SIG_IGN); 148 (void)signal(SIGHUP, SIG_IGN); 149 (void)signal(SIGINT, SIG_IGN); 150 (void)signal(SIGPIPE, SIG_IGN); 151 (void)signal(SIGQUIT, SIG_IGN); 152 (void)signal(SIGTERM, SIG_IGN); 153 (void)signal(SIGCONT, pw_cont); 154 155 /* Create with exact permissions. */ 156 (void)umask(0); 157 #endif 158 initialized = 1; 159 return (0); 160 } 161 162 /* 163 * Lock the master password file. 164 */ 165 int 166 pw_lock(void) 167 { 168 169 if (*masterpasswd == '\0') 170 return (-1); 171 172 /* 173 * If the master password file doesn't exist, the system is hosed. 174 * Might as well try to build one. Set the close-on-exec bit so 175 * that users can't get at the encrypted passwords while editing. 176 * Open should allow flock'ing the file; see 4.4BSD. XXX 177 */ 178 for (;;) { 179 struct stat st; 180 181 lockfd = open(masterpasswd, O_RDONLY, 0); 182 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1) 183 err(1, "%s", masterpasswd); 184 /* XXX vulnerable to race conditions */ 185 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) { 186 if (errno == EWOULDBLOCK) { 187 errx(1, "the password db file is busy"); 188 } else { 189 err(1, "could not lock the passwd file: "); 190 } 191 } 192 193 /* 194 * If the password file was replaced while we were trying to 195 * get the lock, our hardlink count will be 0 and we have to 196 * close and retry. 197 */ 198 if (fstat(lockfd, &st) == -1) 199 err(1, "fstat() failed: "); 200 if (st.st_nlink != 0) 201 break; 202 close(lockfd); 203 lockfd = -1; 204 } 205 return (lockfd); 206 } 207 208 /* 209 * Create and open a presumably safe temp file for editing the password 210 * data, and copy the master password file into it. 211 */ 212 int 213 pw_tmp(int mfd) 214 { 215 char buf[8192]; 216 ssize_t nr; 217 const char *p; 218 int tfd; 219 220 if (*masterpasswd == '\0') 221 return (-1); 222 if ((p = strrchr(masterpasswd, '/'))) 223 ++p; 224 else 225 p = masterpasswd; 226 if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX", 227 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) { 228 errno = ENAMETOOLONG; 229 return (-1); 230 } 231 if ((tfd = mkstemp(tempname)) == -1) 232 return (-1); 233 if (mfd != -1) { 234 while ((nr = read(mfd, buf, sizeof(buf))) > 0) 235 if (write(tfd, buf, (size_t)nr) != nr) 236 break; 237 if (nr != 0) { 238 unlink(tempname); 239 *tempname = '\0'; 240 close(tfd); 241 return (-1); 242 } 243 } 244 return (tfd); 245 } 246 247 /* 248 * Regenerate the password database. 249 */ 250 int 251 pw_mkdb(const char *user) 252 { 253 int pstat; 254 pid_t pid; 255 256 (void)fflush(stderr); 257 switch ((pid = fork())) { 258 case -1: 259 return (-1); 260 case 0: 261 /* child */ 262 if (user == NULL) 263 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 264 "-d", passwd_dir, tempname, (char *)NULL); 265 else 266 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 267 "-d", passwd_dir, "-u", user, tempname, 268 (char *)NULL); 269 _exit(1); 270 /* NOTREACHED */ 271 default: 272 /* parent */ 273 break; 274 } 275 if (waitpid(pid, &pstat, 0) == -1) 276 return (-1); 277 if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) 278 return (0); 279 errno = 0; 280 return (-1); 281 } 282 283 /* 284 * Edit the temp file. Return -1 on error, >0 if the file was modified, 0 285 * if it was not. 286 */ 287 int 288 pw_edit(int notsetuid) 289 { 290 struct sigaction sa, sa_int, sa_quit; 291 sigset_t oldsigset, sigset; 292 struct stat st1, st2; 293 const char *editor; 294 int pstat; 295 296 if ((editor = getenv("EDITOR")) == NULL) 297 editor = _PATH_VI; 298 if (stat(tempname, &st1) == -1) 299 return (-1); 300 sa.sa_handler = SIG_IGN; 301 sigemptyset(&sa.sa_mask); 302 sa.sa_flags = 0; 303 sigaction(SIGINT, &sa, &sa_int); 304 sigaction(SIGQUIT, &sa, &sa_quit); 305 sigemptyset(&sigset); 306 sigaddset(&sigset, SIGCHLD); 307 sigprocmask(SIG_BLOCK, &sigset, &oldsigset); 308 switch ((editpid = fork())) { 309 case -1: 310 return (-1); 311 case 0: 312 sigaction(SIGINT, &sa_int, NULL); 313 sigaction(SIGQUIT, &sa_quit, NULL); 314 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 315 if (notsetuid) { 316 (void)setgid(getgid()); 317 (void)setuid(getuid()); 318 } 319 errno = 0; 320 execlp(editor, basename(editor), tempname, (char *)NULL); 321 _exit(errno); 322 default: 323 /* parent */ 324 break; 325 } 326 for (;;) { 327 if (waitpid(editpid, &pstat, WUNTRACED) == -1) { 328 if (errno == EINTR) 329 continue; 330 unlink(tempname); 331 editpid = -1; 332 break; 333 } else if (WIFSTOPPED(pstat)) { 334 raise(WSTOPSIG(pstat)); 335 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) { 336 editpid = -1; 337 break; 338 } else { 339 unlink(tempname); 340 editpid = -1; 341 break; 342 } 343 } 344 sigaction(SIGINT, &sa_int, NULL); 345 sigaction(SIGQUIT, &sa_quit, NULL); 346 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 347 if (stat(tempname, &st2) == -1) 348 return (-1); 349 return (st1.st_mtime != st2.st_mtime); 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 * Copy password file from one descriptor to another, replacing or adding 413 * a single record on the way. 414 */ 415 int 416 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw) 417 { 418 char buf[8192], *end, *line, *p, *q, *r, t; 419 struct passwd *fpw; 420 size_t len; 421 int eof, readlen; 422 423 if ((line = pw_make(pw)) == NULL) 424 return (-1); 425 426 eof = 0; 427 len = 0; 428 p = q = end = buf; 429 for (;;) { 430 /* find the end of the current line */ 431 for (p = q; q < end && *q != '\0'; ++q) 432 if (*q == '\n') 433 break; 434 435 /* if we don't have a complete line, fill up the buffer */ 436 if (q >= end) { 437 if (eof) 438 break; 439 if ((size_t)(q - p) >= sizeof(buf)) { 440 warnx("passwd line too long"); 441 errno = EINVAL; /* hack */ 442 goto err; 443 } 444 if (p < end) { 445 q = memmove(buf, p, end - p); 446 end -= p - buf; 447 } else { 448 p = q = end = buf; 449 } 450 readlen = read(ffd, end, sizeof(buf) - (end - buf)); 451 if (readlen == -1) 452 goto err; 453 else 454 len = (size_t)readlen; 455 if (len == 0 && p == buf) 456 break; 457 end += len; 458 len = end - buf; 459 if (len < (ssize_t)sizeof(buf)) { 460 eof = 1; 461 if (len > 0 && buf[len - 1] != '\n') 462 ++len, *end++ = '\n'; 463 } 464 continue; 465 } 466 467 /* is it a blank line or a comment? */ 468 for (r = p; r < q && isspace(*r); ++r) 469 /* nothing */ ; 470 if (r == q || *r == '#') { 471 /* yep */ 472 if (write(tfd, p, q - p + 1) != q - p + 1) 473 goto err; 474 ++q; 475 continue; 476 } 477 478 /* is it the one we're looking for? */ 479 t = *q; 480 *q = '\0'; 481 fpw = pw_scan(r, _PWSCAN_MASTER); 482 *q = t; 483 if (strcmp(fpw->pw_name, pw->pw_name) != 0) { 484 /* nope */ 485 free(fpw); 486 if (write(tfd, p, q - p + 1) != q - p + 1) 487 goto err; 488 ++q; 489 continue; 490 } 491 if (old_pw && !pw_equal(fpw, old_pw)) { 492 warnx("entry inconsistent"); 493 free(fpw); 494 errno = EINVAL; /* hack */ 495 goto err; 496 } 497 free(fpw); 498 499 /* it is, replace it */ 500 len = strlen(line); 501 if (write(tfd, line, len) != (int)len) 502 goto err; 503 504 /* we're done, just copy the rest over */ 505 for (;;) { 506 if (write(tfd, q, end - q) != end - q) 507 goto err; 508 q = buf; 509 readlen = read(ffd, buf, sizeof(buf)); 510 if (readlen == 0) 511 break; 512 else 513 len = (size_t)readlen; 514 if (readlen == -1) 515 goto err; 516 end = buf + len; 517 } 518 goto done; 519 } 520 521 /* if we got here, we have a new entry */ 522 len = strlen(line); 523 if ((size_t)write(tfd, line, len) != len || 524 write(tfd, "\n", 1) != 1) 525 goto err; 526 done: 527 free(line); 528 return (0); 529 err: 530 free(line); 531 return (-1); 532 } 533 534 /* 535 * Return the current value of tempname. 536 */ 537 const char * 538 pw_tempname(void) 539 { 540 541 return (tempname); 542 } 543 544 /* 545 * Duplicate a struct passwd. 546 */ 547 struct passwd * 548 pw_dup(const struct passwd *pw) 549 { 550 struct passwd *npw; 551 ssize_t len; 552 553 len = sizeof(*npw) + 554 (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) + 555 (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) + 556 (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) + 557 (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) + 558 (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) + 559 (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0); 560 if ((npw = malloc((size_t)len)) == NULL) 561 return (NULL); 562 memcpy(npw, pw, sizeof(*npw)); 563 len = sizeof(*npw); 564 if (pw->pw_name) { 565 npw->pw_name = ((char *)npw) + len; 566 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1; 567 } 568 if (pw->pw_passwd) { 569 npw->pw_passwd = ((char *)npw) + len; 570 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1; 571 } 572 if (pw->pw_class) { 573 npw->pw_class = ((char *)npw) + len; 574 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1; 575 } 576 if (pw->pw_gecos) { 577 npw->pw_gecos = ((char *)npw) + len; 578 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1; 579 } 580 if (pw->pw_dir) { 581 npw->pw_dir = ((char *)npw) + len; 582 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1; 583 } 584 if (pw->pw_shell) { 585 npw->pw_shell = ((char *)npw) + len; 586 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1; 587 } 588 return (npw); 589 } 590 591 /* 592 * Wrapper around an internal libc function 593 */ 594 struct passwd * 595 pw_scan(const char *line, int flags) 596 { 597 struct passwd pw, *ret; 598 char *bp; 599 600 if ((bp = strdup(line)) == NULL) 601 return (NULL); 602 if (!__pw_scan(bp, &pw, flags)) { 603 free(bp); 604 return (NULL); 605 } 606 ret = pw_dup(&pw); 607 free(bp); 608 return (ret); 609 } 610