lib/libutil/pw_util.c

   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  * $FreeBSD: src/lib/libutil/pw_util.c,v 1.35 2004/05/18 15:53:58 stefanf Exp $
  37  * $DragonFly: src/lib/libutil/pw_util.c,v 1.2 2007/12/30 13:44:33 matthias Exp $
  38  */
  39
  40 /*
  41  * This file is used by all the "password" programs; vipw(8), chpass(1),
  42  * and passwd(1).
  43  */
  44
  45 #include <sys/param.h>
  46 #include <sys/errno.h>
  47 #include <sys/time.h>
  48 #include <sys/resource.h>
  49 #include <sys/stat.h>
  50 #include <sys/wait.h>
  51
  52 #include <ctype.h>
  53 #include <err.h>
  54 #include <fcntl.h>
  55 #include <inttypes.h>
  56 #include <libgen.h>
  57 #include <paths.h>
  58 #include <pwd.h>
  59 #include <signal.h>
  60 #include <stdio.h>
  61 #include <stdlib.h>
  62 #include <string.h>
  63 #include <unistd.h>
  64
  65 #include <libutil.h>
  66
  67 static pid_t editpid = -1;
  68 static int lockfd = -1;
  69 static char masterpasswd[PATH_MAX];
  70 static char passwd_dir[PATH_MAX];
  71 static char tempname[PATH_MAX];
  72 static int initialized;
  73
  74 #if 0
  75 void
  76 pw_cont(int sig)
  77 {
  78
  79         if (editpid != -1)
  80                 kill(editpid, sig);
  81 }
  82 #endif
  83
  84 /*
  85  * Initialize statics and set limits, signals & umask to try to avoid
  86  * interruptions, crashes etc. that might expose passord data.
  87  */
  88 int
  89 pw_init(const char *dir, const char *master)
  90 {
  91 #if 0
  92         struct rlimit rlim;
  93 #endif
  94
  95         if (dir == NULL) {
  96                 strcpy(passwd_dir, _PATH_ETC);
  97         } else {
  98                 if (strlen(dir) >= sizeof(passwd_dir)) {
  99                         errno = ENAMETOOLONG;
 100                         return (-1);
 101                 }
 102                 strcpy(passwd_dir, dir);
 103         }
 104
 105         if (master == NULL) {
 106                 if (dir == NULL) {
 107                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 108                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 109                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 110                         errno = ENAMETOOLONG;
 111                         return (-1);
 112                 }
 113         } else {
 114                 if (strlen(master) >= sizeof(masterpasswd)) {
 115                         errno = ENAMETOOLONG;
 116                         return (-1);
 117                 }
 118                 strcpy(masterpasswd, master);
 119         }
 120
 121         /*
 122          * The code that follows is extremely disruptive to the calling
 123          * process, and is therefore disabled until someone can conceive
 124          * of a realistic scenario where it would fend off a compromise.
 125          * Race conditions concerning the temporary files can be guarded
 126          * against in other ways than masking signals (by checking stat(2)
 127          * results after creation).
 128          */
 129 #if 0
 130         /* Unlimited resource limits. */
 131         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 132         (void)setrlimit(RLIMIT_CPU, &rlim);
 133         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 134         (void)setrlimit(RLIMIT_STACK, &rlim);
 135         (void)setrlimit(RLIMIT_DATA, &rlim);
 136         (void)setrlimit(RLIMIT_RSS, &rlim);
 137
 138         /* Don't drop core (not really necessary, but GP's). */
 139         rlim.rlim_cur = rlim.rlim_max = 0;
 140         (void)setrlimit(RLIMIT_CORE, &rlim);
 141
 142         /* Turn off signals. */
 143         (void)signal(SIGALRM, SIG_IGN);
 144         (void)signal(SIGHUP, SIG_IGN);
 145         (void)signal(SIGINT, SIG_IGN);
 146         (void)signal(SIGPIPE, SIG_IGN);
 147         (void)signal(SIGQUIT, SIG_IGN);
 148         (void)signal(SIGTERM, SIG_IGN);
 149         (void)signal(SIGCONT, pw_cont);
 150
 151         /* Create with exact permissions. */
 152         (void)umask(0);
 153 #endif
 154         initialized = 1;
 155         return (0);
 156 }
 157
 158 /*
 159  * Lock the master password file.
 160  */
 161 int
 162 pw_lock(void)
 163 {
 164
 165         if (*masterpasswd == '\0')
 166                 return (-1);
 167
 168         /*
 169          * If the master password file doesn't exist, the system is hosed.
 170          * Might as well try to build one.  Set the close-on-exec bit so
 171          * that users can't get at the encrypted passwords while editing.
 172          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 173          */
 174         for (;;) {
 175                 struct stat st;
 176
 177                 lockfd = open(masterpasswd, O_RDONLY, 0);
 178                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 179                         err(1, "%s", masterpasswd);
 180                 /* XXX vulnerable to race conditions */
 181                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 182                         if (errno == EWOULDBLOCK) {
 183                                 errx(1, "the password db file is busy");
 184                         } else {
 185                                 err(1, "could not lock the passwd file: ");
 186                         }
 187                 }
 188
 189                 /*
 190                  * If the password file was replaced while we were trying to
 191                  * get the lock, our hardlink count will be 0 and we have to
 192                  * close and retry.
 193                  */
 194                 if (fstat(lockfd, &st) == -1)
 195                         err(1, "fstat() failed: ");
 196                 if (st.st_nlink != 0)
 197                         break;
 198                 close(lockfd);
 199                 lockfd = -1;
 200         }
 201         return (lockfd);
 202 }
 203
 204 /*
 205  * Create and open a presumably safe temp file for editing the password
 206  * data, and copy the master password file into it.
 207  */
 208 int
 209 pw_tmp(int mfd)
 210 {
 211         char buf[8192];
 212         ssize_t nr;
 213         const char *p;
 214         int tfd;
 215
 216         if (*masterpasswd == '\0')
 217                 return (-1);
 218         if ((p = strrchr(masterpasswd, '/')))
 219                 ++p;
 220         else
 221                 p = masterpasswd;
 222         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 223                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 224                 errno = ENAMETOOLONG;
 225                 return (-1);
 226         }
 227         if ((tfd = mkstemp(tempname)) == -1)
 228                 return (-1);
 229         if (mfd != -1) {
 230                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 231                         if (write(tfd, buf, (size_t)nr) != nr)
 232                                 break;
 233                 if (nr != 0) {
 234                         unlink(tempname);
 235                         *tempname = '\0';
 236                         close(tfd);
 237                         return (-1);
 238                 }
 239         }
 240         return (tfd);
 241 }
 242
 243 /*
 244  * Regenerate the password database.
 245  */
 246 int
 247 pw_mkdb(const char *user)
 248 {
 249         int pstat;
 250         pid_t pid;
 251
 252         (void)fflush(stderr);
 253         switch ((pid = fork())) {
 254         case -1:
 255                 return (-1);
 256         case 0:
 257                 /* child */
 258                 if (user == NULL)
 259                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 260                             "-d", passwd_dir, tempname, (char *)NULL);
 261                 else
 262                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 263                             "-d", passwd_dir, "-u", user, tempname,
 264                             (char *)NULL);
 265                 _exit(1);
 266                 /* NOTREACHED */
 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 sigaction sa, sa_int, sa_quit;
 287         sigset_t oldsigset, sigset;
 288         struct stat st1, st2;
 289         const char *editor;
 290         int pstat;
 291
 292         if ((editor = getenv("EDITOR")) == NULL)
 293                 editor = _PATH_VI;
 294         if (stat(tempname, &st1) == -1)
 295                 return (-1);
 296         sa.sa_handler = SIG_IGN;
 297         sigemptyset(&sa.sa_mask);
 298         sa.sa_flags = 0;
 299         sigaction(SIGINT, &sa, &sa_int);
 300         sigaction(SIGQUIT, &sa, &sa_quit);
 301         sigemptyset(&sigset);
 302         sigaddset(&sigset, SIGCHLD);
 303         sigprocmask(SIG_BLOCK, &sigset, &oldsigset);
 304         switch ((editpid = fork())) {
 305         case -1:
 306                 return (-1);
 307         case 0:
 308                 sigaction(SIGINT, &sa_int, NULL);
 309                 sigaction(SIGQUIT, &sa_quit, NULL);
 310                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 311                 if (notsetuid) {
 312                         (void)setgid(getgid());
 313                         (void)setuid(getuid());
 314                 }
 315                 errno = 0;
 316                 execlp(editor, basename(editor), tempname, (char *)NULL);
 317                 _exit(errno);
 318         default:
 319                 /* parent */
 320                 break;
 321         }
 322         for (;;) {
 323                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 324                         if (errno == EINTR)
 325                                 continue;
 326                         unlink(tempname);
 327                         editpid = -1;
 328                         break;
 329                 } else if (WIFSTOPPED(pstat)) {
 330                         raise(WSTOPSIG(pstat));
 331                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 332                         editpid = -1;
 333                         break;
 334                 } else {
 335                         unlink(tempname);
 336                         editpid = -1;
 337                         break;
 338                 }
 339         }
 340         sigaction(SIGINT, &sa_int, NULL);
 341         sigaction(SIGQUIT, &sa_quit, NULL);
 342         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 343         if (stat(tempname, &st2) == -1)
 344                 return (-1);
 345         return (st1.st_mtime != st2.st_mtime);
 346 }
 347
 348 /*
 349  * Clean up.  Preserve errno for the caller's convenience.
 350  */
 351 void
 352 pw_fini(void)
 353 {
 354         int serrno, status;
 355
 356         if (!initialized)
 357                 return;
 358         initialized = 0;
 359         serrno = errno;
 360         if (editpid != -1) {
 361                 kill(editpid, SIGTERM);
 362                 kill(editpid, SIGCONT);
 363                 waitpid(editpid, &status, 0);
 364                 editpid = -1;
 365         }
 366         if (*tempname != '\0') {
 367                 unlink(tempname);
 368                 *tempname = '\0';
 369         }
 370         if (lockfd != -1)
 371                 close(lockfd);
 372         errno = serrno;
 373 }
 374
 375 /*
 376  * Compares two struct pwds.
 377  */
 378 int
 379 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 380 {
 381         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 382             pw1->pw_uid == pw2->pw_uid &&
 383             pw1->pw_gid == pw2->pw_gid &&
 384             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 385             pw1->pw_change == pw2->pw_change &&
 386             pw1->pw_expire == pw2->pw_expire &&
 387             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 388             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 389             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 390 }
 391
 392 /*
 393  * Make a passwd line out of a struct passwd.
 394  */
 395 char *
 396 pw_make(const struct passwd *pw)
 397 {
 398         char *line;
 399
 400         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 401             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 402             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 403             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 404         return line;
 405 }
 406
 407 /*
 408  * Copy password file from one descriptor to another, replacing or adding
 409  * a single record on the way.
 410  */
 411 int
 412 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 413 {
 414         char buf[8192], *end, *line, *p, *q, *r, t;
 415         struct passwd *fpw;
 416         size_t len;
 417         int eof, readlen;
 418
 419         if ((line = pw_make(pw)) == NULL)
 420                 return (-1);
 421
 422         eof = 0;
 423         len = 0;
 424         p = 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                                         ++len, *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                 t = *q;
 476                 *q = '\0';
 477                 fpw = pw_scan(r, _PWSCAN_MASTER);
 478                 *q = t;
 479                 if (strcmp(fpw->pw_name, pw->pw_name) != 0) {
 480                         /* nope */
 481                         free(fpw);
 482                         if (write(tfd, p, q - p + 1) != q - p + 1)
 483                                 goto err;
 484                         ++q;
 485                         continue;
 486                 }
 487                 if (old_pw && !pw_equal(fpw, old_pw)) {
 488                         warnx("entry inconsistent");
 489                         free(fpw);
 490                         errno = EINVAL; /* hack */
 491                         goto err;
 492                 }
 493                 free(fpw);
 494
 495                 /* it is, replace it */
 496                 len = strlen(line);
 497                 if (write(tfd, line, len) != (int)len)
 498                         goto err;
 499
 500                 /* we're done, just copy the rest over */
 501                 for (;;) {
 502                         if (write(tfd, q, end - q) != end - q)
 503                                 goto err;
 504                         q = buf;
 505                         readlen = read(ffd, buf, sizeof(buf));
 506                         if (readlen == 0)
 507                                 break;
 508                         else
 509                                 len = (size_t)readlen;
 510                         if (readlen == -1)
 511                                 goto err;
 512                         end = buf + len;
 513                 }
 514                 goto done;
 515         }
 516
 517         /* if we got here, we have a new entry */
 518         len = strlen(line);
 519         if ((size_t)write(tfd, line, len) != len ||
 520             write(tfd, "\n", 1) != 1)
 521                 goto err;
 522  done:
 523         free(line);
 524         return (0);
 525  err:
 526         free(line);
 527         return (-1);
 528 }
 529
 530 /*
 531  * Return the current value of tempname.
 532  */
 533 const char *
 534 pw_tempname(void)
 535 {
 536
 537         return (tempname);
 538 }
 539
 540 /*
 541  * Duplicate a struct passwd.
 542  */
 543 struct passwd *
 544 pw_dup(const struct passwd *pw)
 545 {
 546         struct passwd *npw;
 547         ssize_t len;
 548
 549         len = sizeof(*npw) +
 550             (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) +
 551             (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) +
 552             (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) +
 553             (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) +
 554             (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) +
 555             (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0);
 556         if ((npw = malloc((size_t)len)) == NULL)
 557                 return (NULL);
 558         memcpy(npw, pw, sizeof(*npw));
 559         len = sizeof(*npw);
 560         if (pw->pw_name) {
 561                 npw->pw_name = ((char *)npw) + len;
 562                 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1;
 563         }
 564         if (pw->pw_passwd) {
 565                 npw->pw_passwd = ((char *)npw) + len;
 566                 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1;
 567         }
 568         if (pw->pw_class) {
 569                 npw->pw_class = ((char *)npw) + len;
 570                 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1;
 571         }
 572         if (pw->pw_gecos) {
 573                 npw->pw_gecos = ((char *)npw) + len;
 574                 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1;
 575         }
 576         if (pw->pw_dir) {
 577                 npw->pw_dir = ((char *)npw) + len;
 578                 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1;
 579         }
 580         if (pw->pw_shell) {
 581                 npw->pw_shell = ((char *)npw) + len;
 582                 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1;
 583         }
 584         return (npw);
 585 }
 586
 587 /*
 588  * Wrapper around an internal libc function
 589  */
 590 struct passwd *
 591 pw_scan(const char *line, int flags)
 592 {
 593         struct passwd pw, *ret;
 594         char *bp;
 595
 596         if ((bp = strdup(line)) == NULL)
 597                 return (NULL);
 598         if (!__pw_scan(bp, &pw, flags)) {
 599                 free(bp);
 600                 return (NULL);
 601         }
 602         ret = pw_dup(&pw);
 603         free(bp);
 604         return (ret);
 605 }