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
  37 #ifndef lint
  38 #if 0
  39 static const char sccsid[] = "@(#)pw_util.c     8.3 (Berkeley) 4/2/94";
  40 #endif
  41 static const char rcsid[] =
  42   "$FreeBSD$";
  43 #endif /* not lint */
  44
  45 /*
  46  * This file is used by all the "password" programs; vipw(8), chpass(1),
  47  * and passwd(1).
  48  */
  49
  50 #include <sys/param.h>
  51 #include <sys/errno.h>
  52 #include <sys/time.h>
  53 #include <sys/resource.h>
  54 #include <sys/stat.h>
  55 #include <sys/wait.h>
  56
  57 #include <ctype.h>
  58 #include <err.h>
  59 #include <fcntl.h>
  60 #include <inttypes.h>
  61 #include <libgen.h>
  62 #include <paths.h>
  63 #include <pwd.h>
  64 #include <signal.h>
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include "libutil.h"
  71
  72 static pid_t editpid = -1;
  73 static int lockfd = -1;
  74 static char masterpasswd[PATH_MAX];
  75 static char passwd_dir[PATH_MAX];
  76 static char tempname[PATH_MAX];
  77 static int initialized;
  78
  79 #if 0
  80 void
  81 pw_cont(int sig)
  82 {
  83
  84         if (editpid != -1)
  85                 kill(editpid, sig);
  86 }
  87 #endif
  88
  89 /*
  90  * Initialize statics and set limits, signals & umask to try to avoid
  91  * interruptions, crashes etc. that might expose passord data.
  92  */
  93 int
  94 pw_init(const char *dir, const char *master)
  95 {
  96 #if 0
  97         struct rlimit rlim;
  98 #endif
  99
 100         if (dir == NULL) {
 101                 strcpy(passwd_dir, _PATH_ETC);
 102         } else {
 103                 if (strlen(dir) >= sizeof(passwd_dir)) {
 104                         errno = ENAMETOOLONG;
 105                         return (-1);
 106                 }
 107                 strcpy(passwd_dir, dir);
 108         }
 109
 110         if (master == NULL) {
 111                 if (dir == NULL) {
 112                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 113                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 114                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 115                         errno = ENAMETOOLONG;
 116                         return (-1);
 117                 }
 118         } else {
 119                 if (strlen(master) >= sizeof(masterpasswd)) {
 120                         errno = ENAMETOOLONG;
 121                         return (-1);
 122                 }
 123                 strcpy(masterpasswd, master);
 124         }
 125
 126         /*
 127          * The code that follows is extremely disruptive to the calling
 128          * process, and is therefore disabled until someone can conceive
 129          * of a realistic scenario where it would fend off a compromise.
 130          * Race conditions concerning the temporary files can be guarded
 131          * against in other ways than masking signals (by checking stat(2)
 132          * results after creation).
 133          */
 134 #if 0
 135         /* Unlimited resource limits. */
 136         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 137         (void)setrlimit(RLIMIT_CPU, &rlim);
 138         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 139         (void)setrlimit(RLIMIT_STACK, &rlim);
 140         (void)setrlimit(RLIMIT_DATA, &rlim);
 141         (void)setrlimit(RLIMIT_RSS, &rlim);
 142
 143         /* Don't drop core (not really necessary, but GP's). */
 144         rlim.rlim_cur = rlim.rlim_max = 0;
 145         (void)setrlimit(RLIMIT_CORE, &rlim);
 146
 147         /* Turn off signals. */
 148         (void)signal(SIGALRM, SIG_IGN);
 149         (void)signal(SIGHUP, SIG_IGN);
 150         (void)signal(SIGINT, SIG_IGN);
 151         (void)signal(SIGPIPE, SIG_IGN);
 152         (void)signal(SIGQUIT, SIG_IGN);
 153         (void)signal(SIGTERM, SIG_IGN);
 154         (void)signal(SIGCONT, pw_cont);
 155
 156         /* Create with exact permissions. */
 157         (void)umask(0);
 158 #endif
 159         initialized = 1;
 160         return (0);
 161 }
 162
 163 /*
 164  * Lock the master password file.
 165  */
 166 int
 167 pw_lock(void)
 168 {
 169
 170         if (*masterpasswd == '\0')
 171                 return (-1);
 172
 173         /*
 174          * If the master password file doesn't exist, the system is hosed.
 175          * Might as well try to build one.  Set the close-on-exec bit so
 176          * that users can't get at the encrypted passwords while editing.
 177          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 178          */
 179         for (;;) {
 180                 struct stat st;
 181
 182                 lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 183                 if (lockfd == -1) {
 184                         if (errno == EWOULDBLOCK) {
 185                                 errx(1, "the password db file is busy");
 186                         } else {
 187                                 err(1, "could not lock the passwd file: ");
 188                         }
 189                 }
 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) == -1)
 197                         err(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;
 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) >= (int)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 (write(tfd, buf, (size_t)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, (char *)NULL);
 263                 else
 264                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 265                             "-d", passwd_dir, "-u", user, tempname,
 266                             (char *)NULL);
 267                 _exit(1);
 268                 /* NOTREACHED */
 269         default:
 270                 /* parent */
 271                 break;
 272         }
 273         if (waitpid(pid, &pstat, 0) == -1)
 274                 return (-1);
 275         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 276                 return (0);
 277         errno = 0;
 278         return (-1);
 279 }
 280
 281 /*
 282  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 283  * if it was not.
 284  */
 285 int
 286 pw_edit(int notsetuid)
 287 {
 288         struct sigaction sa, sa_int, sa_quit;
 289         sigset_t oldsigset, nsigset;
 290         struct stat st1, st2;
 291         const char *editor;
 292         int pstat;
 293
 294         if ((editor = getenv("EDITOR")) == NULL)
 295                 editor = _PATH_VI;
 296         if (stat(tempname, &st1) == -1)
 297                 return (-1);
 298         sa.sa_handler = SIG_IGN;
 299         sigemptyset(&sa.sa_mask);
 300         sa.sa_flags = 0;
 301         sigaction(SIGINT, &sa, &sa_int);
 302         sigaction(SIGQUIT, &sa, &sa_quit);
 303         sigemptyset(&nsigset);
 304         sigaddset(&nsigset, SIGCHLD);
 305         sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
 306         switch ((editpid = fork())) {
 307         case -1:
 308                 return (-1);
 309         case 0:
 310                 sigaction(SIGINT, &sa_int, NULL);
 311                 sigaction(SIGQUIT, &sa_quit, NULL);
 312                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 313                 if (notsetuid) {
 314                         (void)setgid(getgid());
 315                         (void)setuid(getuid());
 316                 }
 317                 errno = 0;
 318                 execlp(editor, basename(editor), tempname, (char *)NULL);
 319                 _exit(errno);
 320         default:
 321                 /* parent */
 322                 break;
 323         }
 324         for (;;) {
 325                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 326                         if (errno == EINTR)
 327                                 continue;
 328                         unlink(tempname);
 329                         editpid = -1;
 330                         break;
 331                 } else if (WIFSTOPPED(pstat)) {
 332                         raise(WSTOPSIG(pstat));
 333                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 334                         editpid = -1;
 335                         break;
 336                 } else {
 337                         unlink(tempname);
 338                         editpid = -1;
 339                         break;
 340                 }
 341         }
 342         sigaction(SIGINT, &sa_int, NULL);
 343         sigaction(SIGQUIT, &sa_quit, NULL);
 344         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 345         if (stat(tempname, &st2) == -1)
 346                 return (-1);
 347         return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
 348             st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
 349 }
 350
 351 /*
 352  * Clean up.  Preserve errno for the caller's convenience.
 353  */
 354 void
 355 pw_fini(void)
 356 {
 357         int serrno, status;
 358
 359         if (!initialized)
 360                 return;
 361         initialized = 0;
 362         serrno = errno;
 363         if (editpid != -1) {
 364                 kill(editpid, SIGTERM);
 365                 kill(editpid, SIGCONT);
 366                 waitpid(editpid, &status, 0);
 367                 editpid = -1;
 368         }
 369         if (*tempname != '\0') {
 370                 unlink(tempname);
 371                 *tempname = '\0';
 372         }
 373         if (lockfd != -1)
 374                 close(lockfd);
 375         errno = serrno;
 376 }
 377
 378 /*
 379  * Compares two struct pwds.
 380  */
 381 int
 382 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 383 {
 384         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 385             pw1->pw_uid == pw2->pw_uid &&
 386             pw1->pw_gid == pw2->pw_gid &&
 387             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 388             pw1->pw_change == pw2->pw_change &&
 389             pw1->pw_expire == pw2->pw_expire &&
 390             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 391             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 392             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 393 }
 394
 395 /*
 396  * Make a passwd line out of a struct passwd.
 397  */
 398 char *
 399 pw_make(const struct passwd *pw)
 400 {
 401         char *line;
 402
 403         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 404             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 405             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 406             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 407         return (line);
 408 }
 409
 410 /*
 411  * Make a passwd line (in v7 format) out of a struct passwd
 412  */
 413 char *
 414 pw_make_v7(const struct passwd *pw)
 415 {
 416         char *line;
 417
 418         asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
 419             (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 420             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 421         return (line);
 422 }
 423
 424 /*
 425  * Copy password file from one descriptor to another, replacing, deleting
 426  * or adding a single record on the way.
 427  */
 428 int
 429 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 430 {
 431         char buf[8192], *end, *line, *p, *q, *r, t;
 432         struct passwd *fpw;
 433         const struct passwd *spw;
 434         size_t len;
 435         int eof, readlen;
 436
 437         if (old_pw == NULL && pw == NULL)
 438                         return (-1);
 439
 440         spw = old_pw;
 441         /* deleting a user */
 442         if (pw == NULL) {
 443                 line = NULL;
 444         } else {
 445                 if ((line = pw_make(pw)) == NULL)
 446                         return (-1);
 447         }
 448
 449         /* adding a user */
 450         if (spw == NULL)
 451                 spw = pw;
 452
 453         eof = 0;
 454         len = 0;
 455         p = q = end = buf;
 456         for (;;) {
 457                 /* find the end of the current line */
 458                 for (p = q; q < end && *q != '\0'; ++q)
 459                         if (*q == '\n')
 460                                 break;
 461
 462                 /* if we don't have a complete line, fill up the buffer */
 463                 if (q >= end) {
 464                         if (eof)
 465                                 break;
 466                         if ((size_t)(q - p) >= sizeof(buf)) {
 467                                 warnx("passwd line too long");
 468                                 errno = EINVAL; /* hack */
 469                                 goto err;
 470                         }
 471                         if (p < end) {
 472                                 q = memmove(buf, p, end - p);
 473                                 end -= p - buf;
 474                         } else {
 475                                 p = q = end = buf;
 476                         }
 477                         readlen = read(ffd, end, sizeof(buf) - (end - buf));
 478                         if (readlen == -1)
 479                                 goto err;
 480                         else
 481                                 len = (size_t)readlen;
 482                         if (len == 0 && p == buf)
 483                                 break;
 484                         end += len;
 485                         len = end - buf;
 486                         if (len < (ssize_t)sizeof(buf)) {
 487                                 eof = 1;
 488                                 if (len > 0 && buf[len - 1] != '\n')
 489                                         ++len, *end++ = '\n';
 490                         }
 491                         continue;
 492                 }
 493
 494                 /* is it a blank line or a comment? */
 495                 for (r = p; r < q && isspace(*r); ++r)
 496                         /* nothing */ ;
 497                 if (r == q || *r == '#') {
 498                         /* yep */
 499                         if (write(tfd, p, q - p + 1) != q - p + 1)
 500                                 goto err;
 501                         ++q;
 502                         continue;
 503                 }
 504
 505                 /* is it the one we're looking for? */
 506
 507                 t = *q;
 508                 *q = '\0';
 509
 510                 fpw = pw_scan(r, PWSCAN_MASTER);
 511
 512                 /*
 513                  * fpw is either the struct passwd for the current line,
 514                  * or NULL if the line is malformed.
 515                  */
 516
 517                 *q = t;
 518                 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
 519                         /* nope */
 520                         if (fpw != NULL)
 521                                 free(fpw);
 522                         if (write(tfd, p, q - p + 1) != q - p + 1)
 523                                 goto err;
 524                         ++q;
 525                         continue;
 526                 }
 527                 if (old_pw && !pw_equal(fpw, old_pw)) {
 528                         warnx("entry inconsistent");
 529                         free(fpw);
 530                         errno = EINVAL; /* hack */
 531                         goto err;
 532                 }
 533                 free(fpw);
 534
 535                 /* it is, replace or remove it */
 536                 if (line != NULL) {
 537                         len = strlen(line);
 538                         if (write(tfd, line, len) != (int)len)
 539                                 goto err;
 540                 } else {
 541                         /* when removed, avoid the \n */
 542                         q++;
 543                 }
 544                 /* we're done, just copy the rest over */
 545                 for (;;) {
 546                         if (write(tfd, q, end - q) != end - q)
 547                                 goto err;
 548                         q = buf;
 549                         readlen = read(ffd, buf, sizeof(buf));
 550                         if (readlen == 0)
 551                                 break;
 552                         else
 553                                 len = (size_t)readlen;
 554                         if (readlen == -1)
 555                                 goto err;
 556                         end = buf + len;
 557                 }
 558                 goto done;
 559         }
 560
 561         /* if we got here, we didn't find the old entry */
 562         if (line == NULL) {
 563                 errno = ENOENT;
 564                 goto err;
 565         }
 566         len = strlen(line);
 567         if ((size_t)write(tfd, line, len) != len ||
 568             write(tfd, "\n", 1) != 1)
 569                 goto err;
 570  done:
 571         if (line != NULL)
 572                 free(line);
 573         return (0);
 574  err:
 575         if (line != NULL)
 576                 free(line);
 577         return (-1);
 578 }
 579
 580 /*
 581  * Return the current value of tempname.
 582  */
 583 const char *
 584 pw_tempname(void)
 585 {
 586
 587         return (tempname);
 588 }
 589
 590 /*
 591  * Duplicate a struct passwd.
 592  */
 593 struct passwd *
 594 pw_dup(const struct passwd *pw)
 595 {
 596         char *dst;
 597         struct passwd *npw;
 598         ssize_t len;
 599
 600         len = sizeof(*npw);
 601         if (pw->pw_name != NULL)
 602                 len += strlen(pw->pw_name) + 1;
 603         if (pw->pw_passwd != NULL)
 604                 len += strlen(pw->pw_passwd) + 1;
 605         if (pw->pw_class != NULL)
 606                 len += strlen(pw->pw_class) + 1;
 607         if (pw->pw_gecos != NULL)
 608                 len += strlen(pw->pw_gecos) + 1;
 609         if (pw->pw_dir != NULL)
 610                 len += strlen(pw->pw_dir) + 1;
 611         if (pw->pw_shell != NULL)
 612                 len += strlen(pw->pw_shell) + 1;
 613         if ((npw = malloc((size_t)len)) == NULL)
 614                 return (NULL);
 615         memcpy(npw, pw, sizeof(*npw));
 616         dst = (char *)npw + sizeof(*npw);
 617         if (pw->pw_name != NULL) {
 618                 npw->pw_name = dst;
 619                 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
 620         }
 621         if (pw->pw_passwd != NULL) {
 622                 npw->pw_passwd = dst;
 623                 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
 624         }
 625         if (pw->pw_class != NULL) {
 626                 npw->pw_class = dst;
 627                 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
 628         }
 629         if (pw->pw_gecos != NULL) {
 630                 npw->pw_gecos = dst;
 631                 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
 632         }
 633         if (pw->pw_dir != NULL) {
 634                 npw->pw_dir = dst;
 635                 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
 636         }
 637         if (pw->pw_shell != NULL) {
 638                 npw->pw_shell = dst;
 639                 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
 640         }
 641         return (npw);
 642 }
 643
 644 #include "pw_scan.h"
 645
 646 /*
 647  * Wrapper around an internal libc function
 648  */
 649 struct passwd *
 650 pw_scan(const char *line, int flags)
 651 {
 652         struct passwd pw, *ret;
 653         char *bp;
 654
 655         if ((bp = strdup(line)) == NULL)
 656                 return (NULL);
 657         if (!__pw_scan(bp, &pw, flags)) {
 658                 free(bp);
 659                 return (NULL);
 660         }
 661         ret = pw_dup(&pw);
 662         free(bp);
 663         return (ret);
 664 }