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  * 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  * $FreeBSD: src/lib/libutil/pw_util.c,v 1.35 2004/05/18 15:53:58 stefanf Exp $
  41  * $DragonFly: src/lib/libutil/pw_util.c,v 1.1 2005/08/01 18:13:20 joerg Exp $
  42  */
  43
  44 /*
  45  * This file is used by all the "password" programs; vipw(8), chpass(1),
  46  * and passwd(1).
  47  */
  48
  49 #include <sys/param.h>
  50 #include <sys/errno.h>
  51 #include <sys/time.h>
  52 #include <sys/resource.h>
  53 #include <sys/stat.h>
  54 #include <sys/wait.h>
  55
  56 #include <ctype.h>
  57 #include <err.h>
  58 #include <fcntl.h>
  59 #include <inttypes.h>
  60 #include <libgen.h>
  61 #include <paths.h>
  62 #include <pwd.h>
  63 #include <signal.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include <libutil.h>
  70
  71 static pid_t editpid = -1;
  72 static int lockfd = -1;
  73 static char masterpasswd[PATH_MAX];
  74 static char passwd_dir[PATH_MAX];
  75 static char tempname[PATH_MAX];
  76 static int initialized;
  77
  78 #if 0
  79 void
  80 pw_cont(int sig)
  81 {
  82
  83         if (editpid != -1)
  84                 kill(editpid, sig);
  85 }
  86 #endif
  87
  88 /*
  89  * Initialize statics and set limits, signals & umask to try to avoid
  90  * interruptions, crashes etc. that might expose passord data.
  91  */
  92 int
  93 pw_init(const char *dir, const char *master)
  94 {
  95 #if 0
  96         struct rlimit rlim;
  97 #endif
  98
  99         if (dir == NULL) {
 100                 strcpy(passwd_dir, _PATH_ETC);
 101         } else {
 102                 if (strlen(dir) >= sizeof(passwd_dir)) {
 103                         errno = ENAMETOOLONG;
 104                         return (-1);
 105                 }
 106                 strcpy(passwd_dir, dir);
 107         }
 108
 109         if (master == NULL) {
 110                 if (dir == NULL) {
 111                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 112                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 113                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 114                         errno = ENAMETOOLONG;
 115                         return (-1);
 116                 }
 117         } else {
 118                 if (strlen(master) >= sizeof(masterpasswd)) {
 119                         errno = ENAMETOOLONG;
 120                         return (-1);
 121                 }
 122                 strcpy(masterpasswd, master);
 123         }
 124
 125         /*
 126          * The code that follows is extremely disruptive to the calling
 127          * process, and is therefore disabled until someone can conceive
 128          * of a realistic scenario where it would fend off a compromise.
 129          * Race conditions concerning the temporary files can be guarded
 130          * against in other ways than masking signals (by checking stat(2)
 131          * results after creation).
 132          */
 133 #if 0
 134         /* Unlimited resource limits. */
 135         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 136         (void)setrlimit(RLIMIT_CPU, &rlim);
 137         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 138         (void)setrlimit(RLIMIT_STACK, &rlim);
 139         (void)setrlimit(RLIMIT_DATA, &rlim);
 140         (void)setrlimit(RLIMIT_RSS, &rlim);
 141
 142         /* Don't drop core (not really necessary, but GP's). */
 143         rlim.rlim_cur = rlim.rlim_max = 0;
 144         (void)setrlimit(RLIMIT_CORE, &rlim);
 145
 146         /* Turn off signals. */
 147         (void)signal(SIGALRM, SIG_IGN);
 148         (void)signal(SIGHUP, SIG_IGN);
 149         (void)signal(SIGINT, SIG_IGN);
 150         (void)signal(SIGPIPE, SIG_IGN);
 151         (void)signal(SIGQUIT, SIG_IGN);
 152         (void)signal(SIGTERM, SIG_IGN);
 153         (void)signal(SIGCONT, pw_cont);
 154
 155         /* Create with exact permissions. */
 156         (void)umask(0);
 157 #endif
 158         initialized = 1;
 159         return (0);
 160 }
 161
 162 /*
 163  * Lock the master password file.
 164  */
 165 int
 166 pw_lock(void)
 167 {
 168
 169         if (*masterpasswd == '\0')
 170                 return (-1);
 171
 172         /*
 173          * If the master password file doesn't exist, the system is hosed.
 174          * Might as well try to build one.  Set the close-on-exec bit so
 175          * that users can't get at the encrypted passwords while editing.
 176          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 177          */
 178         for (;;) {
 179                 struct stat st;
 180
 181                 lockfd = open(masterpasswd, O_RDONLY, 0);
 182                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 183                         err(1, "%s", masterpasswd);
 184                 /* XXX vulnerable to race conditions */
 185                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 186                         if (errno == EWOULDBLOCK) {
 187                                 errx(1, "the password db file is busy");
 188                         } else {
 189                                 err(1, "could not lock the passwd file: ");
 190                         }
 191                 }
 192
 193                 /*
 194                  * If the password file was replaced while we were trying to
 195                  * get the lock, our hardlink count will be 0 and we have to
 196                  * close and retry.
 197                  */
 198                 if (fstat(lockfd, &st) == -1)
 199                         err(1, "fstat() failed: ");
 200                 if (st.st_nlink != 0)
 201                         break;
 202                 close(lockfd);
 203                 lockfd = -1;
 204         }
 205         return (lockfd);
 206 }
 207
 208 /*
 209  * Create and open a presumably safe temp file for editing the password
 210  * data, and copy the master password file into it.
 211  */
 212 int
 213 pw_tmp(int mfd)
 214 {
 215         char buf[8192];
 216         ssize_t nr;
 217         const char *p;
 218         int tfd;
 219
 220         if (*masterpasswd == '\0')
 221                 return (-1);
 222         if ((p = strrchr(masterpasswd, '/')))
 223                 ++p;
 224         else
 225                 p = masterpasswd;
 226         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 227                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 228                 errno = ENAMETOOLONG;
 229                 return (-1);
 230         }
 231         if ((tfd = mkstemp(tempname)) == -1)
 232                 return (-1);
 233         if (mfd != -1) {
 234                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 235                         if (write(tfd, buf, (size_t)nr) != nr)
 236                                 break;
 237                 if (nr != 0) {
 238                         unlink(tempname);
 239                         *tempname = '\0';
 240                         close(tfd);
 241                         return (-1);
 242                 }
 243         }
 244         return (tfd);
 245 }
 246
 247 /*
 248  * Regenerate the password database.
 249  */
 250 int
 251 pw_mkdb(const char *user)
 252 {
 253         int pstat;
 254         pid_t pid;
 255
 256         (void)fflush(stderr);
 257         switch ((pid = fork())) {
 258         case -1:
 259                 return (-1);
 260         case 0:
 261                 /* child */
 262                 if (user == NULL)
 263                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 264                             "-d", passwd_dir, tempname, (char *)NULL);
 265                 else
 266                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 267                             "-d", passwd_dir, "-u", user, tempname,
 268                             (char *)NULL);
 269                 _exit(1);
 270                 /* NOTREACHED */
 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 sigaction sa, sa_int, sa_quit;
 291         sigset_t oldsigset, sigset;
 292         struct stat st1, st2;
 293         const char *editor;
 294         int pstat;
 295
 296         if ((editor = getenv("EDITOR")) == NULL)
 297                 editor = _PATH_VI;
 298         if (stat(tempname, &st1) == -1)
 299                 return (-1);
 300         sa.sa_handler = SIG_IGN;
 301         sigemptyset(&sa.sa_mask);
 302         sa.sa_flags = 0;
 303         sigaction(SIGINT, &sa, &sa_int);
 304         sigaction(SIGQUIT, &sa, &sa_quit);
 305         sigemptyset(&sigset);
 306         sigaddset(&sigset, SIGCHLD);
 307         sigprocmask(SIG_BLOCK, &sigset, &oldsigset);
 308         switch ((editpid = fork())) {
 309         case -1:
 310                 return (-1);
 311         case 0:
 312                 sigaction(SIGINT, &sa_int, NULL);
 313                 sigaction(SIGQUIT, &sa_quit, NULL);
 314                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 315                 if (notsetuid) {
 316                         (void)setgid(getgid());
 317                         (void)setuid(getuid());
 318                 }
 319                 errno = 0;
 320                 execlp(editor, basename(editor), tempname, (char *)NULL);
 321                 _exit(errno);
 322         default:
 323                 /* parent */
 324                 break;
 325         }
 326         for (;;) {
 327                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 328                         if (errno == EINTR)
 329                                 continue;
 330                         unlink(tempname);
 331                         editpid = -1;
 332                         break;
 333                 } else if (WIFSTOPPED(pstat)) {
 334                         raise(WSTOPSIG(pstat));
 335                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 336                         editpid = -1;
 337                         break;
 338                 } else {
 339                         unlink(tempname);
 340                         editpid = -1;
 341                         break;
 342                 }
 343         }
 344         sigaction(SIGINT, &sa_int, NULL);
 345         sigaction(SIGQUIT, &sa_quit, NULL);
 346         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 347         if (stat(tempname, &st2) == -1)
 348                 return (-1);
 349         return (st1.st_mtime != st2.st_mtime);
 350 }
 351
 352 /*
 353  * Clean up.  Preserve errno for the caller's convenience.
 354  */
 355 void
 356 pw_fini(void)
 357 {
 358         int serrno, status;
 359
 360         if (!initialized)
 361                 return;
 362         initialized = 0;
 363         serrno = errno;
 364         if (editpid != -1) {
 365                 kill(editpid, SIGTERM);
 366                 kill(editpid, SIGCONT);
 367                 waitpid(editpid, &status, 0);
 368                 editpid = -1;
 369         }
 370         if (*tempname != '\0') {
 371                 unlink(tempname);
 372                 *tempname = '\0';
 373         }
 374         if (lockfd != -1)
 375                 close(lockfd);
 376         errno = serrno;
 377 }
 378
 379 /*
 380  * Compares two struct pwds.
 381  */
 382 int
 383 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 384 {
 385         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 386             pw1->pw_uid == pw2->pw_uid &&
 387             pw1->pw_gid == pw2->pw_gid &&
 388             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 389             pw1->pw_change == pw2->pw_change &&
 390             pw1->pw_expire == pw2->pw_expire &&
 391             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 392             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 393             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 394 }
 395
 396 /*
 397  * Make a passwd line out of a struct passwd.
 398  */
 399 char *
 400 pw_make(const struct passwd *pw)
 401 {
 402         char *line;
 403
 404         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 405             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 406             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 407             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 408         return line;
 409 }
 410
 411 /*
 412  * Copy password file from one descriptor to another, replacing or adding
 413  * a single record on the way.
 414  */
 415 int
 416 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 417 {
 418         char buf[8192], *end, *line, *p, *q, *r, t;
 419         struct passwd *fpw;
 420         size_t len;
 421         int eof, readlen;
 422
 423         if ((line = pw_make(pw)) == NULL)
 424                 return (-1);
 425
 426         eof = 0;
 427         len = 0;
 428         p = q = end = buf;
 429         for (;;) {
 430                 /* find the end of the current line */
 431                 for (p = q; q < end && *q != '\0'; ++q)
 432                         if (*q == '\n')
 433                                 break;
 434
 435                 /* if we don't have a complete line, fill up the buffer */
 436                 if (q >= end) {
 437                         if (eof)
 438                                 break;
 439                         if ((size_t)(q - p) >= sizeof(buf)) {
 440                                 warnx("passwd line too long");
 441                                 errno = EINVAL; /* hack */
 442                                 goto err;
 443                         }
 444                         if (p < end) {
 445                                 q = memmove(buf, p, end - p);
 446                                 end -= p - buf;
 447                         } else {
 448                                 p = q = end = buf;
 449                         }
 450                         readlen = read(ffd, end, sizeof(buf) - (end - buf));
 451                         if (readlen == -1)
 452                                 goto err;
 453                         else
 454                                 len = (size_t)readlen;
 455                         if (len == 0 && p == buf)
 456                                 break;
 457                         end += len;
 458                         len = end - buf;
 459                         if (len < (ssize_t)sizeof(buf)) {
 460                                 eof = 1;
 461                                 if (len > 0 && buf[len - 1] != '\n')
 462                                         ++len, *end++ = '\n';
 463                         }
 464                         continue;
 465                 }
 466
 467                 /* is it a blank line or a comment? */
 468                 for (r = p; r < q && isspace(*r); ++r)
 469                         /* nothing */ ;
 470                 if (r == q || *r == '#') {
 471                         /* yep */
 472                         if (write(tfd, p, q - p + 1) != q - p + 1)
 473                                 goto err;
 474                         ++q;
 475                         continue;
 476                 }
 477
 478                 /* is it the one we're looking for? */
 479                 t = *q;
 480                 *q = '\0';
 481                 fpw = pw_scan(r, _PWSCAN_MASTER);
 482                 *q = t;
 483                 if (strcmp(fpw->pw_name, pw->pw_name) != 0) {
 484                         /* nope */
 485                         free(fpw);
 486                         if (write(tfd, p, q - p + 1) != q - p + 1)
 487                                 goto err;
 488                         ++q;
 489                         continue;
 490                 }
 491                 if (old_pw && !pw_equal(fpw, old_pw)) {
 492                         warnx("entry inconsistent");
 493                         free(fpw);
 494                         errno = EINVAL; /* hack */
 495                         goto err;
 496                 }
 497                 free(fpw);
 498
 499                 /* it is, replace it */
 500                 len = strlen(line);
 501                 if (write(tfd, line, len) != (int)len)
 502                         goto err;
 503
 504                 /* we're done, just copy the rest over */
 505                 for (;;) {
 506                         if (write(tfd, q, end - q) != end - q)
 507                                 goto err;
 508                         q = buf;
 509                         readlen = read(ffd, buf, sizeof(buf));
 510                         if (readlen == 0)
 511                                 break;
 512                         else
 513                                 len = (size_t)readlen;
 514                         if (readlen == -1)
 515                                 goto err;
 516                         end = buf + len;
 517                 }
 518                 goto done;
 519         }
 520
 521         /* if we got here, we have a new entry */
 522         len = strlen(line);
 523         if ((size_t)write(tfd, line, len) != len ||
 524             write(tfd, "\n", 1) != 1)
 525                 goto err;
 526  done:
 527         free(line);
 528         return (0);
 529  err:
 530         free(line);
 531         return (-1);
 532 }
 533
 534 /*
 535  * Return the current value of tempname.
 536  */
 537 const char *
 538 pw_tempname(void)
 539 {
 540
 541         return (tempname);
 542 }
 543
 544 /*
 545  * Duplicate a struct passwd.
 546  */
 547 struct passwd *
 548 pw_dup(const struct passwd *pw)
 549 {
 550         struct passwd *npw;
 551         ssize_t len;
 552
 553         len = sizeof(*npw) +
 554             (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) +
 555             (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) +
 556             (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) +
 557             (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) +
 558             (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) +
 559             (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0);
 560         if ((npw = malloc((size_t)len)) == NULL)
 561                 return (NULL);
 562         memcpy(npw, pw, sizeof(*npw));
 563         len = sizeof(*npw);
 564         if (pw->pw_name) {
 565                 npw->pw_name = ((char *)npw) + len;
 566                 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1;
 567         }
 568         if (pw->pw_passwd) {
 569                 npw->pw_passwd = ((char *)npw) + len;
 570                 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1;
 571         }
 572         if (pw->pw_class) {
 573                 npw->pw_class = ((char *)npw) + len;
 574                 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1;
 575         }
 576         if (pw->pw_gecos) {
 577                 npw->pw_gecos = ((char *)npw) + len;
 578                 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1;
 579         }
 580         if (pw->pw_dir) {
 581                 npw->pw_dir = ((char *)npw) + len;
 582                 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1;
 583         }
 584         if (pw->pw_shell) {
 585                 npw->pw_shell = ((char *)npw) + len;
 586                 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1;
 587         }
 588         return (npw);
 589 }
 590
 591 /*
 592  * Wrapper around an internal libc function
 593  */
 594 struct passwd *
 595 pw_scan(const char *line, int flags)
 596 {
 597         struct passwd pw, *ret;
 598         char *bp;
 599
 600         if ((bp = strdup(line)) == NULL)
 601                 return (NULL);
 602         if (!__pw_scan(bp, &pw, flags)) {
 603                 free(bp);
 604                 return (NULL);
 605         }
 606         ret = pw_dup(&pw);
 607         free(bp);
 608         return (ret);
 609 }