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