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