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 * @(#)pw_util.c 8.3 (Berkeley) 4/2/94 37 * $FreeBSD: src/lib/libutil/pw_util.c,v 1.38 2007/01/09 01:02:05 imp Exp $ 38 * $DragonFly: src/lib/libutil/pw_util.c,v 1.2 2007/12/30 13:44:33 matthias Exp $ 39 */ 40 41 /* 42 * This file is used by all the "password" programs; vipw(8), chpass(1), 43 * and passwd(1). 44 */ 45 46 #include <sys/param.h> 47 #include <sys/errno.h> 48 #include <sys/time.h> 49 #include <sys/resource.h> 50 #include <sys/stat.h> 51 #include <sys/wait.h> 52 53 #include <ctype.h> 54 #include <err.h> 55 #include <fcntl.h> 56 #include <inttypes.h> 57 #include <libgen.h> 58 #include <paths.h> 59 #include <pwd.h> 60 #include <signal.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <unistd.h> 65 66 #include <libutil.h> 67 68 static pid_t editpid = -1; 69 static int lockfd = -1; 70 static char masterpasswd[PATH_MAX]; 71 static char passwd_dir[PATH_MAX]; 72 static char tempname[PATH_MAX]; 73 static int initialized; 74 75 #if 0 76 void 77 pw_cont(int sig) 78 { 79 80 if (editpid != -1) 81 kill(editpid, sig); 82 } 83 #endif 84 85 /* 86 * Initialize statics and set limits, signals & umask to try to avoid 87 * interruptions, crashes etc. that might expose passord data. 88 */ 89 int 90 pw_init(const char *dir, const char *master) 91 { 92 #if 0 93 struct rlimit rlim; 94 #endif 95 96 if (dir == NULL) { 97 strcpy(passwd_dir, _PATH_ETC); 98 } else { 99 if (strlen(dir) >= sizeof(passwd_dir)) { 100 errno = ENAMETOOLONG; 101 return (-1); 102 } 103 strcpy(passwd_dir, dir); 104 } 105 106 if (master == NULL) { 107 if (dir == NULL) { 108 strcpy(masterpasswd, _PATH_MASTERPASSWD); 109 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s", 110 passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) { 111 errno = ENAMETOOLONG; 112 return (-1); 113 } 114 } else { 115 if (strlen(master) >= sizeof(masterpasswd)) { 116 errno = ENAMETOOLONG; 117 return (-1); 118 } 119 strcpy(masterpasswd, master); 120 } 121 122 /* 123 * The code that follows is extremely disruptive to the calling 124 * process, and is therefore disabled until someone can conceive 125 * of a realistic scenario where it would fend off a compromise. 126 * Race conditions concerning the temporary files can be guarded 127 * against in other ways than masking signals (by checking stat(2) 128 * results after creation). 129 */ 130 #if 0 131 /* Unlimited resource limits. */ 132 rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY; 133 (void)setrlimit(RLIMIT_CPU, &rlim); 134 (void)setrlimit(RLIMIT_FSIZE, &rlim); 135 (void)setrlimit(RLIMIT_STACK, &rlim); 136 (void)setrlimit(RLIMIT_DATA, &rlim); 137 (void)setrlimit(RLIMIT_RSS, &rlim); 138 139 /* Don't drop core (not really necessary, but GP's). */ 140 rlim.rlim_cur = rlim.rlim_max = 0; 141 (void)setrlimit(RLIMIT_CORE, &rlim); 142 143 /* Turn off signals. */ 144 (void)signal(SIGALRM, SIG_IGN); 145 (void)signal(SIGHUP, SIG_IGN); 146 (void)signal(SIGINT, SIG_IGN); 147 (void)signal(SIGPIPE, SIG_IGN); 148 (void)signal(SIGQUIT, SIG_IGN); 149 (void)signal(SIGTERM, SIG_IGN); 150 (void)signal(SIGCONT, pw_cont); 151 152 /* Create with exact permissions. */ 153 (void)umask(0); 154 #endif 155 initialized = 1; 156 return (0); 157 } 158 159 /* 160 * Lock the master password file. 161 */ 162 int 163 pw_lock(void) 164 { 165 166 if (*masterpasswd == '\0') 167 return (-1); 168 169 /* 170 * If the master password file doesn't exist, the system is hosed. 171 * Might as well try to build one. Set the close-on-exec bit so 172 * that users can't get at the encrypted passwords while editing. 173 * Open should allow flock'ing the file; see 4.4BSD. XXX 174 */ 175 for (;;) { 176 struct stat st; 177 178 lockfd = open(masterpasswd, O_RDONLY, 0); 179 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1) 180 err(1, "%s", masterpasswd); 181 /* XXX vulnerable to race conditions */ 182 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) { 183 if (errno == EWOULDBLOCK) { 184 errx(1, "the password db file is busy"); 185 } else { 186 err(1, "could not lock the passwd file: "); 187 } 188 } 189 190 /* 191 * If the password file was replaced while we were trying to 192 * get the lock, our hardlink count will be 0 and we have to 193 * close and retry. 194 */ 195 if (fstat(lockfd, &st) == -1) 196 err(1, "fstat() failed: "); 197 if (st.st_nlink != 0) 198 break; 199 close(lockfd); 200 lockfd = -1; 201 } 202 return (lockfd); 203 } 204 205 /* 206 * Create and open a presumably safe temp file for editing the password 207 * data, and copy the master password file into it. 208 */ 209 int 210 pw_tmp(int mfd) 211 { 212 char buf[8192]; 213 ssize_t nr; 214 const char *p; 215 int tfd; 216 217 if (*masterpasswd == '\0') 218 return (-1); 219 if ((p = strrchr(masterpasswd, '/'))) 220 ++p; 221 else 222 p = masterpasswd; 223 if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX", 224 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) { 225 errno = ENAMETOOLONG; 226 return (-1); 227 } 228 if ((tfd = mkstemp(tempname)) == -1) 229 return (-1); 230 if (mfd != -1) { 231 while ((nr = read(mfd, buf, sizeof(buf))) > 0) 232 if (write(tfd, buf, (size_t)nr) != nr) 233 break; 234 if (nr != 0) { 235 unlink(tempname); 236 *tempname = '\0'; 237 close(tfd); 238 return (-1); 239 } 240 } 241 return (tfd); 242 } 243 244 /* 245 * Regenerate the password database. 246 */ 247 int 248 pw_mkdb(const char *user) 249 { 250 int pstat; 251 pid_t pid; 252 253 (void)fflush(stderr); 254 switch ((pid = fork())) { 255 case -1: 256 return (-1); 257 case 0: 258 /* child */ 259 if (user == NULL) 260 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 261 "-d", passwd_dir, tempname, NULL); 262 else 263 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 264 "-d", passwd_dir, "-u", user, tempname, 265 NULL); 266 _exit(1); 267 /* NOTREACHED */ 268 default: 269 /* parent */ 270 break; 271 } 272 if (waitpid(pid, &pstat, 0) == -1) 273 return (-1); 274 if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) 275 return (0); 276 errno = 0; 277 return (-1); 278 } 279 280 /* 281 * Edit the temp file. Return -1 on error, >0 if the file was modified, 0 282 * if it was not. 283 */ 284 int 285 pw_edit(int notsetuid) 286 { 287 struct sigaction sa, sa_int, sa_quit; 288 sigset_t oldsigset, sigset; 289 struct stat st1, st2; 290 const char *editor; 291 int pstat; 292 293 if ((editor = getenv("EDITOR")) == NULL) 294 editor = _PATH_VI; 295 if (stat(tempname, &st1) == -1) 296 return (-1); 297 sa.sa_handler = SIG_IGN; 298 sigemptyset(&sa.sa_mask); 299 sa.sa_flags = 0; 300 sigaction(SIGINT, &sa, &sa_int); 301 sigaction(SIGQUIT, &sa, &sa_quit); 302 sigemptyset(&sigset); 303 sigaddset(&sigset, SIGCHLD); 304 sigprocmask(SIG_BLOCK, &sigset, &oldsigset); 305 switch ((editpid = fork())) { 306 case -1: 307 return (-1); 308 case 0: 309 sigaction(SIGINT, &sa_int, NULL); 310 sigaction(SIGQUIT, &sa_quit, NULL); 311 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 312 if (notsetuid) { 313 setgid(getgid()); 314 setuid(getuid()); 315 } 316 errno = 0; 317 execlp(editor, basename(editor), tempname, NULL); 318 _exit(errno); 319 default: 320 /* parent */ 321 break; 322 } 323 for (;;) { 324 if (waitpid(editpid, &pstat, WUNTRACED) == -1) { 325 if (errno == EINTR) 326 continue; 327 unlink(tempname); 328 editpid = -1; 329 break; 330 } else if (WIFSTOPPED(pstat)) { 331 raise(WSTOPSIG(pstat)); 332 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) { 333 editpid = -1; 334 break; 335 } else { 336 unlink(tempname); 337 editpid = -1; 338 break; 339 } 340 } 341 sigaction(SIGINT, &sa_int, NULL); 342 sigaction(SIGQUIT, &sa_quit, NULL); 343 sigprocmask(SIG_SETMASK, &oldsigset, NULL); 344 if (stat(tempname, &st2) == -1) 345 return (-1); 346 return (st1.st_mtime != st2.st_mtime); 347 } 348 349 /* 350 * Clean up. Preserve errno for the caller's convenience. 351 */ 352 void 353 pw_fini(void) 354 { 355 int serrno, status; 356 357 if (!initialized) 358 return; 359 initialized = 0; 360 serrno = errno; 361 if (editpid != -1) { 362 kill(editpid, SIGTERM); 363 kill(editpid, SIGCONT); 364 waitpid(editpid, &status, 0); 365 editpid = -1; 366 } 367 if (*tempname != '\0') { 368 unlink(tempname); 369 *tempname = '\0'; 370 } 371 if (lockfd != -1) 372 close(lockfd); 373 errno = serrno; 374 } 375 376 /* 377 * Compares two struct pwds. 378 */ 379 int 380 pw_equal(const struct passwd *pw1, const struct passwd *pw2) 381 { 382 return (strcmp(pw1->pw_name, pw2->pw_name) == 0 && 383 pw1->pw_uid == pw2->pw_uid && 384 pw1->pw_gid == pw2->pw_gid && 385 strcmp(pw1->pw_class, pw2->pw_class) == 0 && 386 pw1->pw_change == pw2->pw_change && 387 pw1->pw_expire == pw2->pw_expire && 388 strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 && 389 strcmp(pw1->pw_dir, pw2->pw_dir) == 0 && 390 strcmp(pw1->pw_shell, pw2->pw_shell) == 0); 391 } 392 393 /* 394 * Make a passwd line out of a struct passwd. 395 */ 396 char * 397 pw_make(const struct passwd *pw) 398 { 399 char *line; 400 401 asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name, 402 pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid, 403 pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire, 404 pw->pw_gecos, pw->pw_dir, pw->pw_shell); 405 return line; 406 } 407 408 /* 409 * Copy password file from one descriptor to another, replacing or adding 410 * a single record on the way. 411 */ 412 int 413 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw) 414 { 415 char buf[8192], *end, *line, *p, *q, *r, t; 416 struct passwd *fpw; 417 size_t len; 418 int eof, readlen; 419 420 if ((line = pw_make(pw)) == NULL) 421 return (-1); 422 423 eof = 0; 424 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 *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? */ 475 476 t = *q; 477 *q = '\0'; 478 479 fpw = pw_scan(r, PWSCAN_MASTER); 480 481 /* 482 * fpw is either the struct passwd for the current line, 483 * or NULL if the line is malformed. 484 */ 485 486 *q = t; 487 if (fpw == NULL || strcmp(fpw->pw_name, pw->pw_name) != 0) { 488 /* nope */ 489 if (fpw != NULL) 490 free(fpw); 491 if (write(tfd, p, q - p + 1) != q - p + 1) 492 goto err; 493 ++q; 494 continue; 495 } 496 if (old_pw && !pw_equal(fpw, old_pw)) { 497 warnx("entry inconsistent"); 498 free(fpw); 499 errno = EINVAL; /* hack */ 500 goto err; 501 } 502 free(fpw); 503 504 /* it is, replace it */ 505 len = strlen(line); 506 if (write(tfd, line, len) != (int)len) 507 goto err; 508 509 /* we're done, just copy the rest over */ 510 for (;;) { 511 if (write(tfd, q, end - q) != end - q) 512 goto err; 513 q = buf; 514 readlen = read(ffd, buf, sizeof(buf)); 515 if (readlen == 0) 516 break; 517 else 518 len = (size_t)readlen; 519 if (readlen == -1) 520 goto err; 521 end = buf + len; 522 } 523 goto done; 524 } 525 526 /* if we got here, we have a new entry */ 527 len = strlen(line); 528 if ((size_t)write(tfd, line, len) != len || 529 write(tfd, "\n", 1) != 1) 530 goto err; 531 done: 532 free(line); 533 return (0); 534 err: 535 free(line); 536 return (-1); 537 } 538 539 /* 540 * Return the current value of tempname. 541 */ 542 const char * 543 pw_tempname(void) 544 { 545 546 return (tempname); 547 } 548 549 /* 550 * Duplicate a struct passwd. 551 */ 552 struct passwd * 553 pw_dup(const struct passwd *pw) 554 { 555 struct passwd *npw; 556 ssize_t len; 557 558 len = sizeof(*npw) + 559 (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) + 560 (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) + 561 (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) + 562 (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) + 563 (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) + 564 (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0); 565 if ((npw = malloc((size_t)len)) == NULL) 566 return (NULL); 567 memcpy(npw, pw, sizeof(*npw)); 568 len = sizeof(*npw); 569 if (pw->pw_name) { 570 npw->pw_name = ((char *)npw) + len; 571 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1; 572 } 573 if (pw->pw_passwd) { 574 npw->pw_passwd = ((char *)npw) + len; 575 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1; 576 } 577 if (pw->pw_class) { 578 npw->pw_class = ((char *)npw) + len; 579 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1; 580 } 581 if (pw->pw_gecos) { 582 npw->pw_gecos = ((char *)npw) + len; 583 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1; 584 } 585 if (pw->pw_dir) { 586 npw->pw_dir = ((char *)npw) + len; 587 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1; 588 } 589 if (pw->pw_shell) { 590 npw->pw_shell = ((char *)npw) + len; 591 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1; 592 } 593 return (npw); 594 } 595 596 #include "pw_scan.h" 597 598 /* 599 * Wrapper around an internal libc function 600 */ 601 struct passwd * 602 pw_scan(const char *line, int flags) 603 { 604 struct passwd pw, *ret; 605 char *bp; 606 607 if ((bp = strdup(line)) == NULL) 608 return (NULL); 609 if (!__pw_scan(bp, &pw, flags)) { 610 free(bp); 611 return (NULL); 612 } 613 ret = pw_dup(&pw); 614 free(bp); 615 return (ret); 616 } 617