pw_util.c revision 113265
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 43static const char sccsid[] = "@(#)pw_util.c 8.3 (Berkeley) 4/2/94"; 44#endif 45static const char rcsid[] = 46 "$FreeBSD: head/lib/libutil/pw_util.c 113265 2003-04-08 18:04:30Z des $"; 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 75static pid_t editpid = -1; 76static int lockfd = -1; 77static char masterpasswd[PATH_MAX]; 78static char passwd_dir[PATH_MAX]; 79static char tempname[PATH_MAX]; 80static int initialized; 81 82void 83pw_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 */ 94int 95pw_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 */ 167int 168pw_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 */ 214int 215pw_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 */ 252int 253pw_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 */ 287int 288pw_edit(int notsetuid) 289{ 290 struct stat st1, st2; 291 const char *editor; 292 char *editcmd; 293 int pstat; 294 295 if ((editor = getenv("EDITOR")) == NULL) 296 editor = _PATH_VI; 297 if (stat(tempname, &st1) == -1) 298 return (-1); 299 switch ((editpid = fork())) { 300 case -1: 301 return (-1); 302 case 0: 303 /* child */ 304 if (notsetuid) { 305 (void)setgid(getgid()); 306 (void)setuid(getuid()); 307 } 308 if (asprintf(&editcmd, "exec %s %s", editor, tempname) == NULL) 309 _exit(EXIT_FAILURE); 310 errno = 0; 311 execl(_PATH_BSHELL, "sh", "-c", editcmd, NULL); 312 free(editcmd); 313 _exit(errno); 314 default: 315 /* parent */ 316 break; 317 } 318 setpgid(editpid, editpid); 319 tcsetpgrp(1, editpid); 320 for (;;) { 321 if (waitpid(editpid, &pstat, WUNTRACED) == -1) { 322 unlink(tempname); 323 return (-1); 324 } else if (WIFSTOPPED(pstat)) { 325 raise(WSTOPSIG(pstat)); 326 tcsetpgrp(1, getpgid(editpid)); 327 kill(editpid, SIGCONT); 328 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) { 329 editpid = -1; 330 break; 331 } else { 332 unlink(tempname); 333 *tempname = '\0'; 334 editpid = -1; 335 return (-1); 336 } 337 } 338 if (stat(tempname, &st2) == -1) 339 return (-1); 340 return (st1.st_mtime != st2.st_mtime); 341} 342 343/* 344 * Clean up. Preserve errno for the caller's convenience. 345 */ 346void 347pw_fini(void) 348{ 349 int serrno, status; 350 351 if (!initialized) 352 return; 353 initialized = 0; 354 serrno = errno; 355 if (editpid != -1) { 356 kill(editpid, SIGTERM); 357 kill(editpid, SIGCONT); 358 waitpid(editpid, &status, 0); 359 editpid = -1; 360 } 361 if (*tempname != '\0') { 362 unlink(tempname); 363 *tempname = '\0'; 364 } 365 if (lockfd != -1) 366 close(lockfd); 367 errno = serrno; 368} 369 370/* 371 * Compares two struct pwds. 372 */ 373int 374pw_equal(struct passwd *pw1, struct passwd *pw2) 375{ 376 return (strcmp(pw1->pw_name, pw2->pw_name) == 0 && 377 pw1->pw_uid == pw2->pw_uid && 378 pw1->pw_gid == pw2->pw_gid && 379 strcmp(pw1->pw_class, pw2->pw_class) == 0 && 380 pw1->pw_change == pw2->pw_change && 381 pw1->pw_expire == pw2->pw_expire && 382 strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 && 383 strcmp(pw1->pw_dir, pw2->pw_dir) == 0 && 384 strcmp(pw1->pw_shell, pw2->pw_shell) == 0); 385} 386 387/* 388 * Make a passwd line out of a struct passwd. 389 */ 390char * 391pw_make(struct passwd *pw) 392{ 393 char *line; 394 395 asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name, 396 pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid, 397 pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire, 398 pw->pw_gecos, pw->pw_dir, pw->pw_shell); 399 return line; 400} 401 402/* 403 * Copy password file from one descriptor to another, replacing or adding 404 * a single record on the way. 405 */ 406int 407pw_copy(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw) 408{ 409 char buf[8192], *end, *line, *p, *q, *r, t; 410 struct passwd *fpw; 411 ssize_t len; 412 int eof; 413 414 if ((line = pw_make(pw)) == NULL) 415 return (-1); 416 417 eof = 0; 418 len = 0; 419 p = q = end = buf; 420 for (;;) { 421 /* find the end of the current line */ 422 for (p = q; q < end && *q != '\0'; ++q) 423 if (*q == '\n') 424 break; 425 426 /* if we don't have a complete line, fill up the buffer */ 427 if (q >= end) { 428 if (eof) 429 break; 430 if (q - p >= sizeof buf) { 431 warnx("passwd line too long"); 432 errno = EINVAL; /* hack */ 433 goto err; 434 } 435 if (p < end) { 436 q = memmove(buf, p, end - p); 437 end -= p - buf; 438 } else { 439 p = q = end = buf; 440 } 441 len = read(ffd, end, sizeof buf - (end - buf)); 442 if (len == -1) 443 goto err; 444 if (len == 0 && p == buf) 445 break; 446 end += len; 447 len = end - buf; 448 if (len < sizeof buf) { 449 eof = 1; 450 if (len > 0 && buf[len - 1] != '\n') 451 ++len, *end++ = '\n'; 452 } 453 continue; 454 } 455 456 /* is it a blank line or a comment? */ 457 for (r = p; r < q && isspace(*r); ++r) 458 /* nothing */ ; 459 if (r == q || *r == '#') { 460 /* yep */ 461 if (write(tfd, p, q - p + 1) != q - p + 1) 462 goto err; 463 ++q; 464 continue; 465 } 466 467 /* is it the one we're looking for? */ 468 t = *q; 469 *q = '\0'; 470 fpw = pw_scan(r, PWSCAN_MASTER); 471 *q = t; 472 if ((old_pw && !pw_equal(fpw, old_pw)) || 473 (!old_pw && strcmp(fpw->pw_name, pw->pw_name))) { 474 /* nope */ 475 free(fpw); 476 if (write(tfd, p, q - p + 1) != q - p + 1) 477 goto err; 478 ++q; 479 continue; 480 } 481 free(fpw); 482 483 /* it is, replace it */ 484 len = strlen(line); 485 if (write(tfd, line, len) != len) 486 goto err; 487 488 /* we're done, just copy the rest over */ 489 for (;;) { 490 if (write(tfd, q, end - q) != end - q) 491 goto err; 492 q = buf; 493 len = read(ffd, buf, sizeof buf); 494 if (len == 0) 495 break; 496 if (len == -1) 497 goto err; 498 end = buf + len; 499 } 500 goto done; 501 } 502 503 /* if we got here, we have a new entry */ 504 len = strlen(line); 505 if (write(tfd, line, len) != len || 506 write(tfd, "\n", 1) != 1) 507 goto err; 508 done: 509 free(line); 510 return (0); 511 err: 512 free(line); 513 return (-1); 514} 515 516/* 517 * Return the current value of tempname. 518 */ 519const char * 520pw_tempname(void) 521{ 522 523 return (tempname); 524} 525 526/* 527 * Duplicate a struct passwd. 528 */ 529struct passwd * 530pw_dup(struct passwd *pw) 531{ 532 struct passwd *npw; 533 size_t len; 534 535 len = sizeof *npw + 536 (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) + 537 (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) + 538 (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) + 539 (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) + 540 (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) + 541 (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0); 542 if ((npw = malloc(len)) == NULL) 543 return (NULL); 544 memcpy(npw, pw, sizeof *npw); 545 len = sizeof *npw; 546 if (pw->pw_name) { 547 npw->pw_name = ((char *)npw) + len; 548 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1; 549 } 550 if (pw->pw_passwd) { 551 npw->pw_passwd = ((char *)npw) + len; 552 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1; 553 } 554 if (pw->pw_class) { 555 npw->pw_class = ((char *)npw) + len; 556 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1; 557 } 558 if (pw->pw_gecos) { 559 npw->pw_gecos = ((char *)npw) + len; 560 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1; 561 } 562 if (pw->pw_dir) { 563 npw->pw_dir = ((char *)npw) + len; 564 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1; 565 } 566 if (pw->pw_shell) { 567 npw->pw_shell = ((char *)npw) + len; 568 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1; 569 } 570 return (npw); 571} 572 573#include "pw_scan.h" 574 575/* 576 * Wrapper around an internal libc function 577 */ 578struct passwd * 579pw_scan(const char *line, int flags) 580{ 581 struct passwd pw, *ret; 582 char *bp; 583 584 if ((bp = strdup(line)) == NULL) 585 return (NULL); 586 if (!__pw_scan(bp, &pw, flags)) { 587 free(bp); 588 return (NULL); 589 } 590 ret = pw_dup(&pw); 591 free(bp); 592 return (ret); 593} 594