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. 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 <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 = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 182                 if (lockfd == -1) {
 183                         if (errno == EWOULDBLOCK) {
 184                                 errx(1, "the password db file is busy");
 185                         } else {
 186                                 err(1, "could not lock the passwd file: ");
 187                         }
 188                 }
 189
 190                 /*
 191                  * If the password file was replaced while we were trying to
 192                  * get the lock, our hardlink count will be 0 and we have to
 193                  * close and retry.
 194                  */
 195                 if (fstat(lockfd, &st) == -1)
 196                         err(1, "fstat() failed: ");
 197                 if (st.st_nlink != 0)
 198                         break;
 199                 close(lockfd);
 200                 lockfd = -1;
 201         }
 202         return (lockfd);
 203 }
 204
 205 /*
 206  * Create and open a presumably safe temp file for editing the password
 207  * data, and copy the master password file into it.
 208  */
 209 int
 210 pw_tmp(int mfd)
 211 {
 212         char buf[8192];
 213         ssize_t nr;
 214         const char *p;
 215         int tfd;
 216
 217         if (*masterpasswd == '\0')
 218                 return (-1);
 219         if ((p = strrchr(masterpasswd, '/')))
 220                 ++p;
 221         else
 222                 p = masterpasswd;
 223         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 224                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 225                 errno = ENAMETOOLONG;
 226                 return (-1);
 227         }
 228         if ((tfd = mkostemp(tempname, 0)) == -1)
 229                 return (-1);
 230         if (mfd != -1) {
 231                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 232                         if (write(tfd, buf, (size_t)nr) != nr)
 233                                 break;
 234                 if (nr != 0) {
 235                         unlink(tempname);
 236                         *tempname = '\0';
 237                         close(tfd);
 238                         return (-1);
 239                 }
 240         }
 241         return (tfd);
 242 }
 243
 244 /*
 245  * Regenerate the password database.
 246  */
 247 int
 248 pw_mkdb(const char *user)
 249 {
 250         int pstat;
 251         pid_t pid;
 252
 253         (void)fflush(stderr);
 254         switch ((pid = fork())) {
 255         case -1:
 256                 return (-1);
 257         case 0:
 258                 /* child */
 259                 if (user == NULL)
 260                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 261                             "-d", passwd_dir, tempname, (char *)NULL);
 262                 else
 263                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 264                             "-d", passwd_dir, "-u", user, tempname,
 265                             (char *)NULL);
 266                 _exit(1);
 267                 /* NOTREACHED */
 268         default:
 269                 /* parent */
 270                 break;
 271         }
 272         if (waitpid(pid, &pstat, 0) == -1)
 273                 return (-1);
 274         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 275                 return (0);
 276         errno = 0;
 277         return (-1);
 278 }
 279
 280 /*
 281  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 282  * if it was not.
 283  */
 284 int
 285 pw_edit(int notsetuid)
 286 {
 287         struct sigaction sa, sa_int, sa_quit;
 288         sigset_t oldsigset, nsigset;
 289         struct stat st1, st2;
 290         const char *editor;
 291         int pstat;
 292
 293         if ((editor = getenv("EDITOR")) == NULL)
 294                 editor = _PATH_VI;
 295         if (stat(tempname, &st1) == -1)
 296                 return (-1);
 297         sa.sa_handler = SIG_IGN;
 298         sigemptyset(&sa.sa_mask);
 299         sa.sa_flags = 0;
 300         sigaction(SIGINT, &sa, &sa_int);
 301         sigaction(SIGQUIT, &sa, &sa_quit);
 302         sigemptyset(&nsigset);
 303         sigaddset(&nsigset, SIGCHLD);
 304         sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
 305         switch ((editpid = fork())) {
 306         case -1:
 307                 return (-1);
 308         case 0:
 309                 sigaction(SIGINT, &sa_int, NULL);
 310                 sigaction(SIGQUIT, &sa_quit, NULL);
 311                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 312                 if (notsetuid) {
 313                         (void)setgid(getgid());
 314                         (void)setuid(getuid());
 315                 }
 316                 errno = 0;
 317                 execlp(editor, editor, tempname, (char *)NULL);
 318                 _exit(errno);
 319         default:
 320                 /* parent */
 321                 break;
 322         }
 323         for (;;) {
 324                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 325                         if (errno == EINTR)
 326                                 continue;
 327                         unlink(tempname);
 328                         editpid = -1;
 329                         break;
 330                 } else if (WIFSTOPPED(pstat)) {
 331                         raise(WSTOPSIG(pstat));
 332                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 333                         editpid = -1;
 334                         break;
 335                 } else {
 336                         unlink(tempname);
 337                         editpid = -1;
 338                         break;
 339                 }
 340         }
 341         sigaction(SIGINT, &sa_int, NULL);
 342         sigaction(SIGQUIT, &sa_quit, NULL);
 343         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 344         if (stat(tempname, &st2) == -1)
 345                 return (-1);
 346         return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
 347             st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
 348 }
 349
 350 /*
 351  * Clean up.  Preserve errno for the caller's convenience.
 352  */
 353 void
 354 pw_fini(void)
 355 {
 356         int serrno, status;
 357
 358         if (!initialized)
 359                 return;
 360         initialized = 0;
 361         serrno = errno;
 362         if (editpid != -1) {
 363                 kill(editpid, SIGTERM);
 364                 kill(editpid, SIGCONT);
 365                 waitpid(editpid, &status, 0);
 366                 editpid = -1;
 367         }
 368         if (*tempname != '\0') {
 369                 unlink(tempname);
 370                 *tempname = '\0';
 371         }
 372         if (lockfd != -1)
 373                 close(lockfd);
 374         errno = serrno;
 375 }
 376
 377 /*
 378  * Compares two struct pwds.
 379  */
 380 int
 381 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 382 {
 383         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 384             pw1->pw_uid == pw2->pw_uid &&
 385             pw1->pw_gid == pw2->pw_gid &&
 386             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 387             pw1->pw_change == pw2->pw_change &&
 388             pw1->pw_expire == pw2->pw_expire &&
 389             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 390             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 391             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 392 }
 393
 394 /*
 395  * Make a passwd line out of a struct passwd.
 396  */
 397 char *
 398 pw_make(const struct passwd *pw)
 399 {
 400         char *line;
 401
 402         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 403             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 404             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 405             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 406         return (line);
 407 }
 408
 409 /*
 410  * Make a passwd line (in v7 format) out of a struct passwd
 411  */
 412 char *
 413 pw_make_v7(const struct passwd *pw)
 414 {
 415         char *line;
 416
 417         asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
 418             (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 419             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 420         return (line);
 421 }
 422
 423 /*
 424  * Copy password file from one descriptor to another, replacing, deleting
 425  * or adding a single record on the way.
 426  */
 427 int
 428 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 429 {
 430         char *buf, *end, *line, *p, *q, *r, *tmp;
 431         struct passwd *fpw;
 432         const struct passwd *spw;
 433         size_t len, size;
 434         int eof, readlen;
 435         char t;
 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         /* initialize the buffer */
 454         if ((buf = malloc(size = 1024)) == NULL)
 455                 goto err;
 456
 457         eof = 0;
 458         len = 0;
 459         p = q = end = buf;
 460         for (;;) {
 461                 /* find the end of the current line */
 462                 for (p = q; q < end && *q != '\0'; ++q)
 463                         if (*q == '\n')
 464                                 break;
 465
 466                 /* if we don't have a complete line, fill up the buffer */
 467                 if (q >= end) {
 468                         if (eof)
 469                                 break;
 470                         while ((size_t)(q - p) >= size) {
 471                                 if ((tmp = reallocarray(buf, 2, size)) == NULL) {
 472                                         warnx("passwd line too long");
 473                                         goto err;
 474                                 }
 475                                 p = tmp + (p - buf);
 476                                 q = tmp + (q - buf);
 477                                 end = tmp + (end - buf);
 478                                 buf = tmp;
 479                                 size = size * 2;
 480                         }
 481                         if (p < end) {
 482                                 q = memmove(buf, p, end - p);
 483                                 end -= p - buf;
 484                         } else {
 485                                 p = q = end = buf;
 486                         }
 487                         readlen = read(ffd, end, size - (end - buf));
 488                         if (readlen == -1)
 489                                 goto err;
 490                         else
 491                                 len = (size_t)readlen;
 492                         if (len == 0 && p == buf)
 493                                 break;
 494                         end += len;
 495                         len = end - buf;
 496                         if (len < size) {
 497                                 eof = 1;
 498                                 if (len > 0 && buf[len - 1] != '\n')
 499                                         ++len, *end++ = '\n';
 500                         }
 501                         continue;
 502                 }
 503
 504                 /* is it a blank line or a comment? */
 505                 for (r = p; r < q && isspace(*r); ++r)
 506                         /* nothing */ ;
 507                 if (r == q || *r == '#') {
 508                         /* yep */
 509                         if (write(tfd, p, q - p + 1) != q - p + 1)
 510                                 goto err;
 511                         ++q;
 512                         continue;
 513                 }
 514
 515                 /* is it the one we're looking for? */
 516
 517                 t = *q;
 518                 *q = '\0';
 519
 520                 fpw = pw_scan(r, PWSCAN_MASTER);
 521
 522                 /*
 523                  * fpw is either the struct passwd for the current line,
 524                  * or NULL if the line is malformed.
 525                  */
 526
 527                 *q = t;
 528                 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
 529                         /* nope */
 530                         if (fpw != NULL)
 531                                 free(fpw);
 532                         if (write(tfd, p, q - p + 1) != q - p + 1)
 533                                 goto err;
 534                         ++q;
 535                         continue;
 536                 }
 537                 if (old_pw && !pw_equal(fpw, old_pw)) {
 538                         warnx("entry inconsistent");
 539                         free(fpw);
 540                         errno = EINVAL; /* hack */
 541                         goto err;
 542                 }
 543                 free(fpw);
 544
 545                 /* it is, replace or remove it */
 546                 if (line != NULL) {
 547                         len = strlen(line);
 548                         if (write(tfd, line, len) != (int)len)
 549                                 goto err;
 550                 } else {
 551                         /* when removed, avoid the \n */
 552                         q++;
 553                 }
 554                 /* we're done, just copy the rest over */
 555                 for (;;) {
 556                         if (write(tfd, q, end - q) != end - q)
 557                                 goto err;
 558                         q = buf;
 559                         readlen = read(ffd, buf, size);
 560                         if (readlen == 0)
 561                                 break;
 562                         else
 563                                 len = (size_t)readlen;
 564                         if (readlen == -1)
 565                                 goto err;
 566                         end = buf + len;
 567                 }
 568                 goto done;
 569         }
 570
 571         /* if we got here, we didn't find the old entry */
 572         if (line == NULL) {
 573                 errno = ENOENT;
 574                 goto err;
 575         }
 576         len = strlen(line);
 577         if ((size_t)write(tfd, line, len) != len ||
 578             write(tfd, "\n", 1) != 1)
 579                 goto err;
 580  done:
 581         free(line);
 582         free(buf);
 583         return (0);
 584  err:
 585         free(line);
 586         free(buf);
 587         return (-1);
 588 }
 589
 590 /*
 591  * Return the current value of tempname.
 592  */
 593 const char *
 594 pw_tempname(void)
 595 {
 596
 597         return (tempname);
 598 }
 599
 600 /*
 601  * Duplicate a struct passwd.
 602  */
 603 struct passwd *
 604 pw_dup(const struct passwd *pw)
 605 {
 606         char *dst;
 607         struct passwd *npw;
 608         ssize_t len;
 609
 610         len = sizeof(*npw);
 611         if (pw->pw_name != NULL)
 612                 len += strlen(pw->pw_name) + 1;
 613         if (pw->pw_passwd != NULL)
 614                 len += strlen(pw->pw_passwd) + 1;
 615         if (pw->pw_class != NULL)
 616                 len += strlen(pw->pw_class) + 1;
 617         if (pw->pw_gecos != NULL)
 618                 len += strlen(pw->pw_gecos) + 1;
 619         if (pw->pw_dir != NULL)
 620                 len += strlen(pw->pw_dir) + 1;
 621         if (pw->pw_shell != NULL)
 622                 len += strlen(pw->pw_shell) + 1;
 623         if ((npw = malloc((size_t)len)) == NULL)
 624                 return (NULL);
 625         memcpy(npw, pw, sizeof(*npw));
 626         dst = (char *)npw + sizeof(*npw);
 627         if (pw->pw_name != NULL) {
 628                 npw->pw_name = dst;
 629                 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
 630         }
 631         if (pw->pw_passwd != NULL) {
 632                 npw->pw_passwd = dst;
 633                 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
 634         }
 635         if (pw->pw_class != NULL) {
 636                 npw->pw_class = dst;
 637                 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
 638         }
 639         if (pw->pw_gecos != NULL) {
 640                 npw->pw_gecos = dst;
 641                 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
 642         }
 643         if (pw->pw_dir != NULL) {
 644                 npw->pw_dir = dst;
 645                 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
 646         }
 647         if (pw->pw_shell != NULL) {
 648                 npw->pw_shell = dst;
 649                 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
 650         }
 651         return (npw);
 652 }
 653
 654 #include "pw_scan.h"
 655
 656 /*
 657  * Wrapper around an internal libc function
 658  */
 659 struct passwd *
 660 pw_scan(const char *line, int flags)
 661 {
 662         struct passwd pw, *ret;
 663         char *bp;
 664
 665         if ((bp = strdup(line)) == NULL)
 666                 return (NULL);
 667         if (!__pw_scan(bp, &pw, flags)) {
 668                 free(bp);
 669                 return (NULL);
 670         }
 671         ret = pw_dup(&pw);
 672         free(bp);
 673         return (ret);
 674 }