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 <err.h> 62 #include <ctype.h> 63 #include <fcntl.h> 64 #include <inttypes.h> 65 #include <paths.h> 66 #include <pwd.h> 67 #include <signal.h> 68 #include <stdio.h> 69 #include <stdlib.h> 70 #include <string.h> 71 #include <unistd.h> 72 73 #include <libutil.h> 74 75 static pid_t editpid = -1; 76 static int lockfd = -1; 77 static char masterpasswd[PATH_MAX]; 78 static char passwd_dir[PATH_MAX]; 79 static char tempname[PATH_MAX]; 80 static int initialized; 81 82 void 83 pw_cont(int sig) 84 { 85 86 if (editpid != -1) 87 kill(editpid, sig); 88 } 89 90 /* 91 * Initialize statics and set limits, signals & umask to try to avoid 92 * interruptions, crashes etc. that might expose passord data. 93 */ 94 int 95 pw_init(const char *dir, const char *master) 96 { 97 #if 0 98 struct rlimit rlim; 99 #endif 100 101 if (dir == NULL) { 102 strcpy(passwd_dir, _PATH_ETC); 103 } else { 104 if (strlen(dir) >= sizeof passwd_dir) { 105 errno = ENAMETOOLONG; 106 return (-1); 107 } 108 strcpy(passwd_dir, dir); 109 } 110 111 if (master == NULL) { 112 if (dir == NULL) { 113 strcpy(masterpasswd, _PATH_MASTERPASSWD); 114 } else if (snprintf(masterpasswd, sizeof masterpasswd, "%s/%s", 115 passwd_dir, _MASTERPASSWD) > sizeof masterpasswd) { 116 errno = ENAMETOOLONG; 117 return (-1); 118 } 119 } else { 120 if (strlen(master) >= sizeof masterpasswd) { 121 errno = ENAMETOOLONG; 122 return (-1); 123 } 124 strcpy(masterpasswd, master); 125 } 126 127 /* 128 * The code that follows is extremely disruptive to the calling 129 * process, and is therefore disabled until someone can conceive 130 * of a realistic scenario where it would fend off a compromise. 131 * Race conditions concerning the temporary files can be guarded 132 * against in other ways than masking signals (by checking stat(2) 133 * results after creation). 134 */ 135 #if 0 136 /* Unlimited resource limits. */ 137 rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY; 138 (void)setrlimit(RLIMIT_CPU, &rlim); 139 (void)setrlimit(RLIMIT_FSIZE, &rlim); 140 (void)setrlimit(RLIMIT_STACK, &rlim); 141 (void)setrlimit(RLIMIT_DATA, &rlim); 142 (void)setrlimit(RLIMIT_RSS, &rlim); 143 144 /* Don't drop core (not really necessary, but GP's). */ 145 rlim.rlim_cur = rlim.rlim_max = 0; 146 (void)setrlimit(RLIMIT_CORE, &rlim); 147 148 /* Turn off signals. */ 149 (void)signal(SIGALRM, SIG_IGN); 150 (void)signal(SIGHUP, SIG_IGN); 151 (void)signal(SIGINT, SIG_IGN); 152 (void)signal(SIGPIPE, SIG_IGN); 153 (void)signal(SIGQUIT, SIG_IGN); 154 (void)signal(SIGTERM, SIG_IGN); 155 (void)signal(SIGCONT, pw_cont); 156 157 /* Create with exact permissions. */ 158 (void)umask(0); 159 #endif 160 initialized = 1; 161 return (0); 162 } 163 164 /* 165 * Lock the master password file. 166 */ 167 int 168 pw_lock(void) 169 { 170 171 if (*masterpasswd == '\0') 172 return (-1); 173 174 /* 175 * If the master password file doesn't exist, the system is hosed. 176 * Might as well try to build one. Set the close-on-exec bit so 177 * that users can't get at the encrypted passwords while editing. 178 * Open should allow flock'ing the file; see 4.4BSD. XXX 179 */ 180 for (;;) { 181 struct stat st; 182 183 lockfd = open(masterpasswd, O_RDONLY, 0); 184 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1) 185 err(1, "%s", masterpasswd); 186 /* XXX vulnerable to race conditions */ 187 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) { 188 if (errno == EWOULDBLOCK) { 189 errx(1, "the password db file is busy"); 190 } else { 191 err(1, "could not lock the passwd file: "); 192 } 193 } 194 195 /* 196 * If the password file was replaced while we were trying to 197 * get the lock, our hardlink count will be 0 and we have to 198 * close and retry. 199 */ 200 if (fstat(lockfd, &st) == -1) 201 err(1, "fstat() failed: "); 202 if (st.st_nlink != 0) 203 break; 204 close(lockfd); 205 lockfd = -1; 206 } 207 return (lockfd); 208 } 209 210 /* 211 * Create and open a presumably safe temp file for editing the password 212 * data, and copy the master password file into it. 213 */ 214 int 215 pw_tmp(int mfd) 216 { 217 char buf[8192]; 218 ssize_t nr, nw; 219 const char *p; 220 int tfd; 221 222 if (*masterpasswd == '\0') 223 return (-1); 224 if ((p = strrchr(masterpasswd, '/'))) 225 ++p; 226 else 227 p = masterpasswd; 228 if (snprintf(tempname, sizeof tempname, "%.*spw.XXXXXX", 229 (int)(p - masterpasswd), masterpasswd) >= sizeof tempname) { 230 errno = ENAMETOOLONG; 231 return (-1); 232 } 233 if ((tfd = mkstemp(tempname)) == -1) 234 return (-1); 235 if (mfd != -1) { 236 while ((nr = read(mfd, buf, sizeof buf)) > 0) 237 if ((nw = write(tfd, buf, nr)) != nr) 238 break; 239 if (nr != 0) { 240 unlink(tempname); 241 *tempname = '\0'; 242 close(tfd); 243 return (-1); 244 } 245 } 246 return (tfd); 247 } 248 249 /* 250 * Regenerate the password database. 251 */ 252 int 253 pw_mkdb(const char *user) 254 { 255 int pstat; 256 pid_t pid; 257 258 (void)fflush(stderr); 259 switch ((pid = fork())) { 260 case -1: 261 return (-1); 262 case 0: 263 /* child */ 264 if (user == NULL) 265 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 266 "-d", passwd_dir, tempname, NULL); 267 else 268 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p", 269 "-d", passwd_dir, "-u", user, tempname, NULL); 270 _exit(1); 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 stat st1, st2; 291 const char *editor; 292 char *editcmd; 293 int editcmdlen; 294 int pstat; 295 296 if ((editor = getenv("EDITOR")) == NULL) 297 editor = _PATH_VI; 298 if (stat(tempname, &st1) == -1) 299 return (-1); 300 switch ((editpid = fork())) { 301 case -1: 302 return (-1); 303 case 0: 304 /* child */ 305 if (notsetuid) { 306 (void)setgid(getgid()); 307 (void)setuid(getuid()); 308 } 309 if ((editcmdlen = sysconf(_SC_ARG_MAX) - 6) <= 0 || 310 (editcmd = malloc(editcmdlen)) == NULL) 311 _exit(EXIT_FAILURE); 312 if (snprintf(editcmd, editcmdlen, "%s %s", 313 editor, tempname) >= editcmdlen) { 314 free(editcmd); /* pedantry */ 315 _exit(EXIT_FAILURE); 316 } 317 errno = 0; 318 execl(_PATH_BSHELL, "sh", "-c", editcmd, NULL); 319 free(editcmd); 320 _exit(errno); 321 default: 322 /* parent */ 323 break; 324 } 325 for (;;) { 326 editpid = waitpid(editpid, &pstat, WUNTRACED); 327 if (editpid == -1) { 328 unlink(tempname); 329 return (-1); 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 *tempname = '\0'; 338 editpid = -1; 339 return (-1); 340 } 341 } 342 if (stat(tempname, &st2) == -1) 343 return (-1); 344 return (st1.st_mtime != st2.st_mtime); 345 } 346 347 /* 348 * Clean up. Preserve errno for the caller's convenience. 349 */ 350 void 351 pw_fini(void) 352 { 353 int serrno, status; 354 355 if (!initialized) 356 return; 357 initialized = 0; 358 serrno = errno; 359 if (editpid != -1) { 360 kill(editpid, SIGTERM); 361 kill(editpid, SIGCONT); 362 waitpid(editpid, &status, 0); 363 editpid = -1; 364 } 365 if (*tempname != '\0') { 366 unlink(tempname); 367 *tempname = '\0'; 368 } 369 if (lockfd != -1) 370 close(lockfd); 371 errno = serrno; 372 } 373 374 /* 375 * Compares two struct pwds. 376 */ 377 int 378 pw_equal(struct passwd *pw1, struct passwd *pw2) 379 { 380 return (strcmp(pw1->pw_name, pw2->pw_name) == 0 && 381 pw1->pw_uid == pw2->pw_uid && 382 pw1->pw_gid == pw2->pw_gid && 383 strcmp(pw1->pw_class, pw2->pw_class) == 0 && 384 pw1->pw_change == pw2->pw_change && 385 pw1->pw_expire == pw2->pw_expire && 386 strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 && 387 strcmp(pw1->pw_dir, pw2->pw_dir) == 0 && 388 strcmp(pw1->pw_shell, pw2->pw_shell) == 0); 389 } 390 391 /* 392 * Make a passwd line out of a struct passwd. 393 */ 394 char * 395 pw_make(struct passwd *pw) 396 { 397 char *line; 398 399 asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name, 400 pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid, 401 pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire, 402 pw->pw_gecos, pw->pw_dir, pw->pw_shell); 403 return line; 404 } 405 406 /* 407 * Copy password file from one descriptor to another, replacing or adding 408 * a single record on the way. 409 */ 410 int 411 pw_copy(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw) 412 { 413 char buf[8192], *end, *line, *p, *q, *r, t; 414 struct passwd *fpw; 415 ssize_t len; 416 int eof; 417 418 if ((line = pw_make(pw)) == NULL) 419 return (-1); 420 421 eof = 0; 422 len = 0; 423 p = q = end = buf; 424 for (;;) { 425 /* find the end of the current line */ 426 for (p = q; q < end && *q != '\0'; ++q) 427 if (*q == '\n') 428 break; 429 430 /* if we don't have a complete line, fill up the buffer */ 431 if (q >= end) { 432 if (eof) 433 break; 434 if (q - p >= sizeof buf) { 435 warnx("passwd line too long"); 436 errno = EINVAL; /* hack */ 437 goto err; 438 } 439 if (p < end) { 440 q = memmove(buf, p, end - p); 441 end -= p - buf; 442 } else { 443 p = q = end = buf; 444 } 445 len = read(ffd, end, sizeof buf - (end - buf)); 446 if (len == -1) 447 goto err; 448 if (len == 0 && p == buf) 449 break; 450 end += len; 451 len = end - buf; 452 if (len < sizeof buf) { 453 eof = 1; 454 if (len > 0 && buf[len - 1] != '\n') 455 ++len, *end++ = '\n'; 456 } 457 continue; 458 } 459 460 /* is it a blank line or a comment? */ 461 for (r = p; r < q && isspace(*r); ++r) 462 /* nothing */ ; 463 if (r == q || *r == '#') { 464 /* yep */ 465 if (write(tfd, p, q - p + 1) != q - p + 1) 466 goto err; 467 ++q; 468 continue; 469 } 470 471 /* is it the one we're looking for? */ 472 t = *q; 473 *q = '\0'; 474 fpw = pw_scan(r, PWSCAN_MASTER); 475 *q = t; 476 if ((old_pw && !pw_equal(fpw, old_pw)) || 477 (!old_pw && strcmp(fpw->pw_name, pw->pw_name))) { 478 /* nope */ 479 free(fpw); 480 if (write(tfd, p, q - p + 1) != q - p + 1) 481 goto err; 482 ++q; 483 continue; 484 } 485 free(fpw); 486 487 /* it is, replace it */ 488 len = strlen(line); 489 if (write(tfd, line, len) != len) 490 goto err; 491 492 /* we're done, just copy the rest over */ 493 for (;;) { 494 if (write(tfd, q, end - q) != end - q) 495 goto err; 496 q = buf; 497 len = read(ffd, buf, sizeof buf); 498 if (len == 0) 499 break; 500 if (len == -1) 501 goto err; 502 end = buf + len; 503 } 504 goto done; 505 } 506 507 /* if we got here, we have a new entry */ 508 len = strlen(line); 509 if (write(tfd, line, len) != len || 510 write(tfd, "\n", 1) != 1) 511 goto err; 512 done: 513 free(line); 514 return (0); 515 err: 516 free(line); 517 return (-1); 518 } 519 520 /* 521 * Return the current value of tempname. 522 */ 523 const char * 524 pw_tempname(void) 525 { 526 527 return (tempname); 528 } 529 530 /* 531 * Duplicate a struct passwd. 532 */ 533 struct passwd * 534 pw_dup(struct passwd *pw) 535 { 536 struct passwd *npw; 537 size_t len; 538 539 len = sizeof *npw + 540 (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) + 541 (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) + 542 (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) + 543 (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) + 544 (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) + 545 (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0); 546 if ((npw = malloc(len)) == NULL) 547 return (NULL); 548 memcpy(npw, pw, sizeof *npw); 549 len = sizeof *npw; 550 if (pw->pw_name) { 551 npw->pw_name = ((char *)npw) + len; 552 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1; 553 } 554 if (pw->pw_passwd) { 555 npw->pw_passwd = ((char *)npw) + len; 556 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1; 557 } 558 if (pw->pw_class) { 559 npw->pw_class = ((char *)npw) + len; 560 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1; 561 } 562 if (pw->pw_gecos) { 563 npw->pw_gecos = ((char *)npw) + len; 564 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1; 565 } 566 if (pw->pw_dir) { 567 npw->pw_dir = ((char *)npw) + len; 568 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1; 569 } 570 if (pw->pw_shell) { 571 npw->pw_shell = ((char *)npw) + len; 572 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1; 573 } 574 return (npw); 575 } 576 577 #include "pw_scan.h" 578 579 /* 580 * Wrapper around an internal libc function 581 */ 582 struct passwd * 583 pw_scan(const char *line, int flags) 584 { 585 struct passwd pw, *ret; 586 char *bp; 587 588 if ((bp = strdup(line)) == NULL) 589 return (NULL); 590 if (!__pw_scan(bp, &pw, flags)) { 591 free(bp); 592 return (NULL); 593 } 594 ret = pw_dup(&pw); 595 free(bp); 596 return (ret); 597 } 598