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 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * $FreeBSD: src/lib/libutil/pw_util.c,v 1.35 2004/05/18 15:53:58 stefanf Exp $ 37 * $DragonFly: src/lib/libutil/pw_util.c,v 1.2 2007/12/30 13:44:33 matthias Exp $ 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 <libgen.h> 57 #include <paths.h> 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <unistd.h> 64 65 #include <libutil.h> 66 67 static pid_t editpid = -1; 68 static int lockfd = -1; 69 static char masterpasswd[PATH_MAX]; 70 static char passwd_dir[PATH_MAX]; 71 static char tempname[PATH_MAX]; 72 static int initialized; 73 74 #if 0 75 void 76 pw_cont(int sig) 77 { 78 79 if (editpid != -1) 80 kill(editpid, sig); 81 } 82 #endif 83 84 /* 85 * Initialize statics and set limits, signals & umask to try to avoid 86 * interruptions, crashes etc. that might expose passord data. 87 */ 88 int 89 pw_init(const char *dir, const char *master) 90 { 91 #if 0 92 struct rlimit rlim; 93 #endif 94 95 if (dir == NULL) { 96 strcpy(passwd_dir, _PATH_ETC); 97 } else { 98 if (strlen(dir) >= sizeof(passwd_dir)) { 99 errno = ENAMETOOLONG; 100 return (-1); 101 } 102 strcpy(passwd_dir, dir); 103 } 104 105 if (master == NULL) { 106 if (dir == NULL) { 107 strcpy(masterpasswd, _PATH_MASTERPASSWD); 108 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s", 109 passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) { 110 errno = ENAMETOOLONG; 111 return (-1); 112 } 113 } else { 114 if (strlen(master) >= sizeof(masterpasswd)) { 115 errno = ENAMETOOLONG; 116 return (-1); 117 } 118 strcpy(masterpasswd, master); 119 } 120 121 /* 122 * The code that follows is extremely disruptive to the calling 123 * process, and is therefore disabled until someone can conceive 124 * of a realistic scenario where it would fend off a compromise. 125 * Race conditions concerning the temporary files can be guarded 126 * against in other ways than masking signals (by checking stat(2) 127 * results after creation). 128 */ 129 #if 0 130 /* Unlimited resource limits. */ 131 rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY; 132 (void)setrlimit(RLIMIT_CPU, &rlim); 133 (void)setrlimit(RLIMIT_FSIZE, &rlim); 134 (void)setrlimit(RLIMIT_STACK, &rlim); 135 (void)setrlimit(RLIMIT_DATA, &rlim); 136 (void)setrlimit(RLIMIT_RSS, &rlim); 137 138 /* Don't drop core (not really necessary, but GP's). */ 139 rlim.rlim_cur = rlim.rlim_max = 0; 140 (void)setrlimit(RLIMIT_CORE, &rlim); 141 142 /* Turn off signals. */ 143 (void)signal(SIGALRM, SIG_IGN); 144 (void)signal(SIGHUP, SIG_IGN); 145 (void)signal(SIGINT, SIG_IGN); 146 (void)signal(SIGPIPE, SIG_IGN); 147 (void)signal(SIGQUIT, SIG_IGN); 148 (void)signal(SIGTERM, SIG_IGN); 149 (void)signal(SIGCONT, pw_cont); 150 151 /* Create with exact permissions. */ 152 (void)umask(0); 153 #endif 154 initialized = 1; 155 return (0); 156 } 157 158 /* 159 * Lock the master password file. 160 */ 161 int 162 pw_lock(void) 163 { 164 165 if (*masterpasswd == '\0') 166 return (-1); 167 168 /* 169 * If the master password file doesn't exist, the system is hosed. 170 * Might as well try to build one. Set the close-on-exec bit so 171 * that users can't get at the encrypted passwords while editing. 172 * Open should allow flock'ing the file; see 4.4BSD. XXX 173 */ 174 for (;;) { 175 struct stat st; 176 177 lockfd = open(masterpasswd, O_RDONLY, 0); 178 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1) 179 err(1, "%s", masterpasswd); 180 /* XXX vulnerable to race conditions */ 181 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) { 182 if (errno == EWOULDBLOCK) { 183 errx(1, "the password db file is busy"); 184 } else { 185 err(1, "could not lock the passwd file: "); 186 } 187 } 188 189 /* 190 * If the password file was replaced while we were trying to 191 * get the lock, our hardlink count will be 0 and we have to 192 * close and retry. 193 */ 194 if (fstat(lockfd, &st) == -1) 195 err(1, "fstat() failed: "); 196 if (st.st_nlink != 0) 197 break; 198 close(lockfd); 199 lockfd = -1; 200 } 201 return (lockfd); 202 } 203 204 /* 205 * Create and open a presumably safe temp file for editing the password 206 * data, and copy the master password file into it. 207 */ 208 int 209 pw_tmp(int mfd) 210 { 211 char buf[8192]; 212 ssize_t nr; 213 const char *p; 214 int tfd; 215 216 if (*masterpasswd == '\0') 217 return (-1); 218 if ((p = strrchr(masterpasswd, '/'))) 219 ++p; 220 else 221 p = masterpasswd; 222 if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX", 223 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) { 224 errno = ENAMETOOLONG; 225 return (-1); 226 } 227 if ((tfd = mkstemp(tempname)) == -1) 228 return (-1); 229 if (mfd != -1) { 230 while ((nr = read(mfd, buf, sizeof(buf))) > 0) 231 if (write(tfd, buf, (size_t)nr) != nr) 232 break; 233 if (nr != 0) { 234 unlink(tempname); 235 *tempname = '\0'; 236 close(tfd); 237 return (-1); 238 } 239 } 240 return (tfd); 241 } 242 243 /* 244 * Regenerate the password database. 245 */ 246 int 247 pw_mkdb(const char *user) 248 { 249 int pstat; 250 pid_t pid; 251 252 (void)fflush(stderr); 253 switch ((pid = fork())) { 254 case -1: 255 return (-1); 256 case 0: 257 /* child */ 258 if (user == NULL) 259 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 260 "-d", passwd_dir, tempname, (char *)NULL); 261 else 262 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 263 "-d", passwd_dir, "-u", user, tempname, 264 (char *)NULL); 265 _exit(1); 266 /* NOTREACHED */ 267 default: 268 /* parent */ 269 break; 270 } 271 if (waitpid(pid, &pstat, 0) == -1) 272 return (-1); 273 if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) 274 return (0); 275 errno = 0; 276 return (-1); 277 } 278 279 /* 280 * Edit the temp file. Return -1 on error, >0 if the file was modified, 0 281 * if it was not. 282 */ 283 int 284 pw_edit(int notsetuid) 285 { 286 struct sigaction sa, sa_int, sa_quit; 287 sigset_t oldsigset, sigset; 288 struct stat st1, st2; 289 const char *editor; 290 int pstat; 291 292 if ((editor = getenv("EDITOR")) == NULL) 293 editor = _PATH_VI; 294 if (stat(tempname, &st1) == -1) 295 return (-1); 296 sa.sa_handler = SIG_IGN; 297 sigemptyset(&sa.sa_mask); 298 sa.sa_flags = 0; 299 sigaction(SIGINT, &sa, &sa_int); 300 sigaction(SIGQUIT, &sa, &sa_quit); 301 sigemptyset(&sigset); 302 sigaddset(&sigset, SIGCHLD); 303 sigprocmask(SIG_BLOCK, &sigset, &oldsigset); 304 switch ((editpid = fork())) { 305 case -1: 306 return (-1); 307 case 0: 308 sigaction(SIGINT, &sa_int, NULL); 309 sigaction(SIGQUIT, &sa_quit, NULL); 310 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 311 if (notsetuid) { 312 (void)setgid(getgid()); 313 (void)setuid(getuid()); 314 } 315 errno = 0; 316 execlp(editor, basename(editor), tempname, (char *)NULL); 317 _exit(errno); 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) && WEXITSTATUS(pstat) == 0) { 332 editpid = -1; 333 break; 334 } else { 335 unlink(tempname); 336 editpid = -1; 337 break; 338 } 339 } 340 sigaction(SIGINT, &sa_int, NULL); 341 sigaction(SIGQUIT, &sa_quit, NULL); 342 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 343 if (stat(tempname, &st2) == -1) 344 return (-1); 345 return (st1.st_mtime != st2.st_mtime); 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 * Copy password file from one descriptor to another, replacing or adding 409 * a single record on the way. 410 */ 411 int 412 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw) 413 { 414 char buf[8192], *end, *line, *p, *q, *r, t; 415 struct passwd *fpw; 416 size_t len; 417 int eof, readlen; 418 419 if ((line = pw_make(pw)) == NULL) 420 return (-1); 421 422 eof = 0; 423 len = 0; 424 p = q = end = buf; 425 for (;;) { 426 /* find the end of the current line */ 427 for (p = q; q < end && *q != '\0'; ++q) 428 if (*q == '\n') 429 break; 430 431 /* if we don't have a complete line, fill up the buffer */ 432 if (q >= end) { 433 if (eof) 434 break; 435 if ((size_t)(q - p) >= sizeof(buf)) { 436 warnx("passwd line too long"); 437 errno = EINVAL; /* hack */ 438 goto err; 439 } 440 if (p < end) { 441 q = memmove(buf, p, end - p); 442 end -= p - buf; 443 } else { 444 p = q = end = buf; 445 } 446 readlen = read(ffd, end, sizeof(buf) - (end - buf)); 447 if (readlen == -1) 448 goto err; 449 else 450 len = (size_t)readlen; 451 if (len == 0 && p == buf) 452 break; 453 end += len; 454 len = end - buf; 455 if (len < (ssize_t)sizeof(buf)) { 456 eof = 1; 457 if (len > 0 && buf[len - 1] != '\n') 458 ++len, *end++ = '\n'; 459 } 460 continue; 461 } 462 463 /* is it a blank line or a comment? */ 464 for (r = p; r < q && isspace(*r); ++r) 465 /* nothing */ ; 466 if (r == q || *r == '#') { 467 /* yep */ 468 if (write(tfd, p, q - p + 1) != q - p + 1) 469 goto err; 470 ++q; 471 continue; 472 } 473 474 /* is it the one we're looking for? */ 475 t = *q; 476 *q = '\0'; 477 fpw = pw_scan(r, _PWSCAN_MASTER); 478 *q = t; 479 if (strcmp(fpw->pw_name, pw->pw_name) != 0) { 480 /* nope */ 481 free(fpw); 482 if (write(tfd, p, q - p + 1) != q - p + 1) 483 goto err; 484 ++q; 485 continue; 486 } 487 if (old_pw && !pw_equal(fpw, old_pw)) { 488 warnx("entry inconsistent"); 489 free(fpw); 490 errno = EINVAL; /* hack */ 491 goto err; 492 } 493 free(fpw); 494 495 /* it is, replace it */ 496 len = strlen(line); 497 if (write(tfd, line, len) != (int)len) 498 goto err; 499 500 /* we're done, just copy the rest over */ 501 for (;;) { 502 if (write(tfd, q, end - q) != end - q) 503 goto err; 504 q = buf; 505 readlen = read(ffd, buf, sizeof(buf)); 506 if (readlen == 0) 507 break; 508 else 509 len = (size_t)readlen; 510 if (readlen == -1) 511 goto err; 512 end = buf + len; 513 } 514 goto done; 515 } 516 517 /* if we got here, we have a new entry */ 518 len = strlen(line); 519 if ((size_t)write(tfd, line, len) != len || 520 write(tfd, "\n", 1) != 1) 521 goto err; 522 done: 523 free(line); 524 return (0); 525 err: 526 free(line); 527 return (-1); 528 } 529 530 /* 531 * Return the current value of tempname. 532 */ 533 const char * 534 pw_tempname(void) 535 { 536 537 return (tempname); 538 } 539 540 /* 541 * Duplicate a struct passwd. 542 */ 543 struct passwd * 544 pw_dup(const struct passwd *pw) 545 { 546 struct passwd *npw; 547 ssize_t len; 548 549 len = sizeof(*npw) + 550 (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) + 551 (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) + 552 (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) + 553 (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) + 554 (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) + 555 (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0); 556 if ((npw = malloc((size_t)len)) == NULL) 557 return (NULL); 558 memcpy(npw, pw, sizeof(*npw)); 559 len = sizeof(*npw); 560 if (pw->pw_name) { 561 npw->pw_name = ((char *)npw) + len; 562 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1; 563 } 564 if (pw->pw_passwd) { 565 npw->pw_passwd = ((char *)npw) + len; 566 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1; 567 } 568 if (pw->pw_class) { 569 npw->pw_class = ((char *)npw) + len; 570 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1; 571 } 572 if (pw->pw_gecos) { 573 npw->pw_gecos = ((char *)npw) + len; 574 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1; 575 } 576 if (pw->pw_dir) { 577 npw->pw_dir = ((char *)npw) + len; 578 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1; 579 } 580 if (pw->pw_shell) { 581 npw->pw_shell = ((char *)npw) + len; 582 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1; 583 } 584 return (npw); 585 } 586 587 /* 588 * Wrapper around an internal libc function 589 */ 590 struct passwd * 591 pw_scan(const char *line, int flags) 592 { 593 struct passwd pw, *ret; 594 char *bp; 595 596 if ((bp = strdup(line)) == NULL) 597 return (NULL); 598 if (!__pw_scan(bp, &pw, flags)) { 599 free(bp); 600 return (NULL); 601 } 602 ret = pw_dup(&pw); 603 free(bp); 604 return (ret); 605 } 606