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         struct stat st;
 100
 101         if (dir == NULL) {
 102                 strcpy(passwd_dir, _PATH_ETC);
 103         } else {
 104                 if (strlen(dir) >= sizeof(passwd_dir)) {
 105                         errno = ENAMETOOLONG;
 106                         return (-1);
 107                 }
 108                 strcpy(passwd_dir, dir);
 109         }
 110
 111         if (master == NULL) {
 112                 if (dir == NULL) {
 113                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 114                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 115                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 116                         errno = ENAMETOOLONG;
 117                         return (-1);
 118                 }
 119         } else {
 120                 if (strlen(master) >= sizeof(masterpasswd)) {
 121                         errno = ENAMETOOLONG;
 122                         return (-1);
 123                 }
 124                 strcpy(masterpasswd, master);
 125         }
 126
 127         if (stat(masterpasswd, &st) == -1)
 128                 return (-1);
 129
 130         if (S_ISDIR(st.st_mode)) {
 131                 errno = EISDIR;
 132                 return (-1);
 133         }
 134
 135         /*
 136          * The code that follows is extremely disruptive to the calling
 137          * process, and is therefore disabled until someone can conceive
 138          * of a realistic scenario where it would fend off a compromise.
 139          * Race conditions concerning the temporary files can be guarded
 140          * against in other ways than masking signals (by checking stat(2)
 141          * results after creation).
 142          */
 143 #if 0
 144         /* Unlimited resource limits. */
 145         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 146         (void)setrlimit(RLIMIT_CPU, &rlim);
 147         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 148         (void)setrlimit(RLIMIT_STACK, &rlim);
 149         (void)setrlimit(RLIMIT_DATA, &rlim);
 150         (void)setrlimit(RLIMIT_RSS, &rlim);
 151
 152         /* Don't drop core (not really necessary, but GP's). */
 153         rlim.rlim_cur = rlim.rlim_max = 0;
 154         (void)setrlimit(RLIMIT_CORE, &rlim);
 155
 156         /* Turn off signals. */
 157         (void)signal(SIGALRM, SIG_IGN);
 158         (void)signal(SIGHUP, SIG_IGN);
 159         (void)signal(SIGINT, SIG_IGN);
 160         (void)signal(SIGPIPE, SIG_IGN);
 161         (void)signal(SIGQUIT, SIG_IGN);
 162         (void)signal(SIGTERM, SIG_IGN);
 163         (void)signal(SIGCONT, pw_cont);
 164
 165         /* Create with exact permissions. */
 166         (void)umask(0);
 167 #endif
 168         initialized = 1;
 169         return (0);
 170 }
 171
 172 /*
 173  * Lock the master password file.
 174  */
 175 int
 176 pw_lock(void)
 177 {
 178
 179         if (*masterpasswd == '\0')
 180                 return (-1);
 181
 182         /*
 183          * If the master password file doesn't exist, the system is hosed.
 184          * Might as well try to build one.  Set the close-on-exec bit so
 185          * that users can't get at the encrypted passwords while editing.
 186          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 187          */
 188         for (;;) {
 189                 struct stat st;
 190
 191                 lockfd = open(masterpasswd, O_RDONLY, 0);
 192                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 193                         err(1, "%s", masterpasswd);
 194                 /* XXX vulnerable to race conditions */
 195                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 196                         if (errno == EWOULDBLOCK) {
 197                                 errx(1, "the password db file is busy");
 198                         } else {
 199                                 err(1, "could not lock the passwd file: ");
 200                         }
 201                 }
 202
 203                 /*
 204                  * If the password file was replaced while we were trying to
 205                  * get the lock, our hardlink count will be 0 and we have to
 206                  * close and retry.
 207                  */
 208                 if (fstat(lockfd, &st) == -1)
 209                         err(1, "fstat() failed: ");
 210                 if (st.st_nlink != 0)
 211                         break;
 212                 close(lockfd);
 213                 lockfd = -1;
 214         }
 215         return (lockfd);
 216 }
 217
 218 /*
 219  * Create and open a presumably safe temp file for editing the password
 220  * data, and copy the master password file into it.
 221  */
 222 int
 223 pw_tmp(int mfd)
 224 {
 225         char buf[8192];
 226         ssize_t nr;
 227         const char *p;
 228         int tfd;
 229
 230         if (*masterpasswd == '\0')
 231                 return (-1);
 232         if ((p = strrchr(masterpasswd, '/')))
 233                 ++p;
 234         else
 235                 p = masterpasswd;
 236         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 237                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 238                 errno = ENAMETOOLONG;
 239                 return (-1);
 240         }
 241         if ((tfd = mkstemp(tempname)) == -1)
 242                 return (-1);
 243         if (mfd != -1) {
 244                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 245                         if (write(tfd, buf, (size_t)nr) != nr)
 246                                 break;
 247                 if (nr != 0) {
 248                         unlink(tempname);
 249                         *tempname = '\0';
 250                         close(tfd);
 251                         return (-1);
 252                 }
 253         }
 254         return (tfd);
 255 }
 256
 257 /*
 258  * Regenerate the password database.
 259  */
 260 int
 261 pw_mkdb(const char *user)
 262 {
 263         int pstat;
 264         pid_t pid;
 265
 266         (void)fflush(stderr);
 267         switch ((pid = fork())) {
 268         case -1:
 269                 return (-1);
 270         case 0:
 271                 /* child */
 272                 if (user == NULL)
 273                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 274                             "-d", passwd_dir, tempname, (char *)NULL);
 275                 else
 276                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 277                             "-d", passwd_dir, "-u", user, tempname,
 278                             (char *)NULL);
 279                 _exit(1);
 280                 /* NOTREACHED */
 281         default:
 282                 /* parent */
 283                 break;
 284         }
 285         if (waitpid(pid, &pstat, 0) == -1)
 286                 return (-1);
 287         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 288                 return (0);
 289         errno = 0;
 290         return (-1);
 291 }
 292
 293 /*
 294  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 295  * if it was not.
 296  */
 297 int
 298 pw_edit(int notsetuid)
 299 {
 300         struct sigaction sa, sa_int, sa_quit;
 301         sigset_t oldsigset, nsigset;
 302         struct stat st1, st2;
 303         const char *editor;
 304         int pstat;
 305
 306         if ((editor = getenv("EDITOR")) == NULL)
 307                 editor = _PATH_VI;
 308         if (stat(tempname, &st1) == -1)
 309                 return (-1);
 310         sa.sa_handler = SIG_IGN;
 311         sigemptyset(&sa.sa_mask);
 312         sa.sa_flags = 0;
 313         sigaction(SIGINT, &sa, &sa_int);
 314         sigaction(SIGQUIT, &sa, &sa_quit);
 315         sigemptyset(&nsigset);
 316         sigaddset(&nsigset, SIGCHLD);
 317         sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
 318         switch ((editpid = fork())) {
 319         case -1:
 320                 return (-1);
 321         case 0:
 322                 sigaction(SIGINT, &sa_int, NULL);
 323                 sigaction(SIGQUIT, &sa_quit, NULL);
 324                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 325                 if (notsetuid) {
 326                         (void)setgid(getgid());
 327                         (void)setuid(getuid());
 328                 }
 329                 errno = 0;
 330                 execlp(editor, basename(editor), tempname, (char *)NULL);
 331                 _exit(errno);
 332         default:
 333                 /* parent */
 334                 break;
 335         }
 336         for (;;) {
 337                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 338                         if (errno == EINTR)
 339                                 continue;
 340                         unlink(tempname);
 341                         editpid = -1;
 342                         break;
 343                 } else if (WIFSTOPPED(pstat)) {
 344                         raise(WSTOPSIG(pstat));
 345                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 346                         editpid = -1;
 347                         break;
 348                 } else {
 349                         unlink(tempname);
 350                         editpid = -1;
 351                         break;
 352                 }
 353         }
 354         sigaction(SIGINT, &sa_int, NULL);
 355         sigaction(SIGQUIT, &sa_quit, NULL);
 356         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 357         if (stat(tempname, &st2) == -1)
 358                 return (-1);
 359         return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
 360             st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
 361 }
 362
 363 /*
 364  * Clean up.  Preserve errno for the caller's convenience.
 365  */
 366 void
 367 pw_fini(void)
 368 {
 369         int serrno, status;
 370
 371         if (!initialized)
 372                 return;
 373         initialized = 0;
 374         serrno = errno;
 375         if (editpid != -1) {
 376                 kill(editpid, SIGTERM);
 377                 kill(editpid, SIGCONT);
 378                 waitpid(editpid, &status, 0);
 379                 editpid = -1;
 380         }
 381         if (*tempname != '\0') {
 382                 unlink(tempname);
 383                 *tempname = '\0';
 384         }
 385         if (lockfd != -1)
 386                 close(lockfd);
 387         errno = serrno;
 388 }
 389
 390 /*
 391  * Compares two struct pwds.
 392  */
 393 int
 394 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 395 {
 396         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 397             pw1->pw_uid == pw2->pw_uid &&
 398             pw1->pw_gid == pw2->pw_gid &&
 399             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 400             pw1->pw_change == pw2->pw_change &&
 401             pw1->pw_expire == pw2->pw_expire &&
 402             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 403             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 404             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 405 }
 406
 407 /*
 408  * Make a passwd line out of a struct passwd.
 409  */
 410 char *
 411 pw_make(const struct passwd *pw)
 412 {
 413         char *line;
 414
 415         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 416             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 417             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 418             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 419         return (line);
 420 }
 421
 422 /*
 423  * Make a passwd line (in v7 format) out of a struct passwd
 424  */
 425 char *
 426 pw_make_v7(const struct passwd *pw)
 427 {
 428         char *line;
 429
 430         asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
 431             (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 432             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 433         return (line);
 434 }
 435
 436 /*
 437  * Copy password file from one descriptor to another, replacing, deleting
 438  * or adding a single record on the way.
 439  */
 440 int
 441 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 442 {
 443         char buf[8192], *end, *line, *p, *q, *r, t;
 444         struct passwd *fpw;
 445         const struct passwd *spw;
 446         size_t len;
 447         int eof, readlen;
 448
 449         if (old_pw == NULL && pw == NULL)
 450                         return (-1);
 451
 452         spw = old_pw;
 453         /* deleting a user */
 454         if (pw == NULL) {
 455                 line = NULL;
 456         } else {
 457                 if ((line = pw_make(pw)) == NULL)
 458                         return (-1);
 459         }
 460
 461         /* adding a user */
 462         if (spw == NULL)
 463                 spw = pw;
 464
 465         eof = 0;
 466         len = 0;
 467         p = q = end = buf;
 468         for (;;) {
 469                 /* find the end of the current line */
 470                 for (p = q; q < end && *q != '\0'; ++q)
 471                         if (*q == '\n')
 472                                 break;
 473
 474                 /* if we don't have a complete line, fill up the buffer */
 475                 if (q >= end) {
 476                         if (eof)
 477                                 break;
 478                         if ((size_t)(q - p) >= sizeof(buf)) {
 479                                 warnx("passwd line too long");
 480                                 errno = EINVAL; /* hack */
 481                                 goto err;
 482                         }
 483                         if (p < end) {
 484                                 q = memmove(buf, p, end - p);
 485                                 end -= p - buf;
 486                         } else {
 487                                 p = q = end = buf;
 488                         }
 489                         readlen = read(ffd, end, sizeof(buf) - (end - buf));
 490                         if (readlen == -1)
 491                                 goto err;
 492                         else
 493                                 len = (size_t)readlen;
 494                         if (len == 0 && p == buf)
 495                                 break;
 496                         end += len;
 497                         len = end - buf;
 498                         if (len < (ssize_t)sizeof(buf)) {
 499                                 eof = 1;
 500                                 if (len > 0 && buf[len - 1] != '\n')
 501                                         ++len, *end++ = '\n';
 502                         }
 503                         continue;
 504                 }
 505
 506                 /* is it a blank line or a comment? */
 507                 for (r = p; r < q && isspace(*r); ++r)
 508                         /* nothing */ ;
 509                 if (r == q || *r == '#') {
 510                         /* yep */
 511                         if (write(tfd, p, q - p + 1) != q - p + 1)
 512                                 goto err;
 513                         ++q;
 514                         continue;
 515                 }
 516
 517                 /* is it the one we're looking for? */
 518
 519                 t = *q;
 520                 *q = '\0';
 521
 522                 fpw = pw_scan(r, PWSCAN_MASTER);
 523
 524                 /*
 525                  * fpw is either the struct passwd for the current line,
 526                  * or NULL if the line is malformed.
 527                  */
 528
 529                 *q = t;
 530                 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
 531                         /* nope */
 532                         if (fpw != NULL)
 533                                 free(fpw);
 534                         if (write(tfd, p, q - p + 1) != q - p + 1)
 535                                 goto err;
 536                         ++q;
 537                         continue;
 538                 }
 539                 if (old_pw && !pw_equal(fpw, old_pw)) {
 540                         warnx("entry inconsistent");
 541                         free(fpw);
 542                         errno = EINVAL; /* hack */
 543                         goto err;
 544                 }
 545                 free(fpw);
 546
 547                 /* it is, replace or remove it */
 548                 if (line != NULL) {
 549                         len = strlen(line);
 550                         if (write(tfd, line, len) != (int)len)
 551                                 goto err;
 552                 } else {
 553                         /* when removed, avoid the \n */
 554                         q++;
 555                 }
 556                 /* we're done, just copy the rest over */
 557                 for (;;) {
 558                         if (write(tfd, q, end - q) != end - q)
 559                                 goto err;
 560                         q = buf;
 561                         readlen = read(ffd, buf, sizeof(buf));
 562                         if (readlen == 0)
 563                                 break;
 564                         else
 565                                 len = (size_t)readlen;
 566                         if (readlen == -1)
 567                                 goto err;
 568                         end = buf + len;
 569                 }
 570                 goto done;
 571         }
 572
 573         /* if we got here, we didn't find the old entry */
 574         if (line == NULL) {
 575                 errno = ENOENT;
 576                 goto err;
 577         }
 578         len = strlen(line);
 579         if ((size_t)write(tfd, line, len) != len ||
 580             write(tfd, "\n", 1) != 1)
 581                 goto err;
 582  done:
 583         if (line != NULL)
 584                 free(line);
 585         return (0);
 586  err:
 587         if (line != NULL)
 588                 free(line);
 589         return (-1);
 590 }
 591
 592 /*
 593  * Return the current value of tempname.
 594  */
 595 const char *
 596 pw_tempname(void)
 597 {
 598
 599         return (tempname);
 600 }
 601
 602 /*
 603  * Duplicate a struct passwd.
 604  */
 605 struct passwd *
 606 pw_dup(const struct passwd *pw)
 607 {
 608         char *dst;
 609         struct passwd *npw;
 610         ssize_t len;
 611
 612         len = sizeof(*npw);
 613         if (pw->pw_name != NULL)
 614                 len += strlen(pw->pw_name) + 1;
 615         if (pw->pw_passwd != NULL)
 616                 len += strlen(pw->pw_passwd) + 1;
 617         if (pw->pw_class != NULL)
 618                 len += strlen(pw->pw_class) + 1;
 619         if (pw->pw_gecos != NULL)
 620                 len += strlen(pw->pw_gecos) + 1;
 621         if (pw->pw_dir != NULL)
 622                 len += strlen(pw->pw_dir) + 1;
 623         if (pw->pw_shell != NULL)
 624                 len += strlen(pw->pw_shell) + 1;
 625         if ((npw = malloc((size_t)len)) == NULL)
 626                 return (NULL);
 627         memcpy(npw, pw, sizeof(*npw));
 628         dst = (char *)npw + sizeof(*npw);
 629         if (pw->pw_name != NULL) {
 630                 npw->pw_name = dst;
 631                 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
 632         }
 633         if (pw->pw_passwd != NULL) {
 634                 npw->pw_passwd = dst;
 635                 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
 636         }
 637         if (pw->pw_class != NULL) {
 638                 npw->pw_class = dst;
 639                 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
 640         }
 641         if (pw->pw_gecos != NULL) {
 642                 npw->pw_gecos = dst;
 643                 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
 644         }
 645         if (pw->pw_dir != NULL) {
 646                 npw->pw_dir = dst;
 647                 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
 648         }
 649         if (pw->pw_shell != NULL) {
 650                 npw->pw_shell = dst;
 651                 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
 652         }
 653         return (npw);
 654 }
 655
 656 #include "pw_scan.h"
 657
 658 /*
 659  * Wrapper around an internal libc function
 660  */
 661 struct passwd *
 662 pw_scan(const char *line, int flags)
 663 {
 664         struct passwd pw, *ret;
 665         char *bp;
 666
 667         if ((bp = strdup(line)) == NULL)
 668                 return (NULL);
 669         if (!__pw_scan(bp, &pw, flags)) {
 670                 free(bp);
 671                 return (NULL);
 672         }
 673         ret = pw_dup(&pw);
 674         free(bp);
 675         return (ret);
 676 }