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. 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  * @(#)pw_util.c        8.3 (Berkeley) 4/2/94
  37  * $FreeBSD: head/lib/libutil/pw_util.c 244744 2012-12-27 20:24:44Z bapt $
  38  */
  39
  40 /*
  41  * This file is used by all the "password" programs; vipw(8), chpass(1),
  42  * and passwd(1).
  43  */
  44
  45 #include <sys/param.h>
  46 #include <sys/errno.h>
  47 #include <sys/time.h>
  48 #include <sys/resource.h>
  49 #include <sys/stat.h>
  50 #include <sys/wait.h>
  51
  52 #include <ctype.h>
  53 #include <err.h>
  54 #include <fcntl.h>
  55 #include <inttypes.h>
  56 #include <libgen.h>
  57 #include <paths.h>
  58 #include <pwd.h>
  59 #include <signal.h>
  60 #include <stdio.h>
  61 #include <stdlib.h>
  62 #include <string.h>
  63 #include <unistd.h>
  64 #include <libutil.h>
  65
  66 static pid_t editpid = -1;
  67 static int lockfd = -1;
  68 static char masterpasswd[PATH_MAX];
  69 static char passwd_dir[PATH_MAX];
  70 static char tempname[PATH_MAX];
  71 static int initialized;
  72
  73 #if 0
  74 void
  75 pw_cont(int sig)
  76 {
  77
  78         if (editpid != -1)
  79                 kill(editpid, sig);
  80 }
  81 #endif
  82
  83 /*
  84  * Initialize statics and set limits, signals & umask to try to avoid
  85  * interruptions, crashes etc. that might expose passord data.
  86  */
  87 int
  88 pw_init(const char *dir, const char *master)
  89 {
  90 #if 0
  91         struct rlimit rlim;
  92 #endif
  93
  94         if (dir == NULL) {
  95                 strcpy(passwd_dir, _PATH_ETC);
  96         } else {
  97                 if (strlen(dir) >= sizeof(passwd_dir)) {
  98                         errno = ENAMETOOLONG;
  99                         return (-1);
 100                 }
 101                 strcpy(passwd_dir, dir);
 102         }
 103
 104         if (master == NULL) {
 105                 if (dir == NULL) {
 106                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 107                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 108                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 109                         errno = ENAMETOOLONG;
 110                         return (-1);
 111                 }
 112         } else {
 113                 if (strlen(master) >= sizeof(masterpasswd)) {
 114                         errno = ENAMETOOLONG;
 115                         return (-1);
 116                 }
 117                 strcpy(masterpasswd, master);
 118         }
 119
 120         /*
 121          * The code that follows is extremely disruptive to the calling
 122          * process, and is therefore disabled until someone can conceive
 123          * of a realistic scenario where it would fend off a compromise.
 124          * Race conditions concerning the temporary files can be guarded
 125          * against in other ways than masking signals (by checking stat(2)
 126          * results after creation).
 127          */
 128 #if 0
 129         /* Unlimited resource limits. */
 130         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 131         (void)setrlimit(RLIMIT_CPU, &rlim);
 132         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 133         (void)setrlimit(RLIMIT_STACK, &rlim);
 134         (void)setrlimit(RLIMIT_DATA, &rlim);
 135         (void)setrlimit(RLIMIT_RSS, &rlim);
 136
 137         /* Don't drop core (not really necessary, but GP's). */
 138         rlim.rlim_cur = rlim.rlim_max = 0;
 139         (void)setrlimit(RLIMIT_CORE, &rlim);
 140
 141         /* Turn off signals. */
 142         (void)signal(SIGALRM, SIG_IGN);
 143         (void)signal(SIGHUP, SIG_IGN);
 144         (void)signal(SIGINT, SIG_IGN);
 145         (void)signal(SIGPIPE, SIG_IGN);
 146         (void)signal(SIGQUIT, SIG_IGN);
 147         (void)signal(SIGTERM, SIG_IGN);
 148         (void)signal(SIGCONT, pw_cont);
 149
 150         /* Create with exact permissions. */
 151         (void)umask(0);
 152 #endif
 153         initialized = 1;
 154         return (0);
 155 }
 156
 157 /*
 158  * Lock the master password file.
 159  */
 160 int
 161 pw_lock(void)
 162 {
 163
 164         if (*masterpasswd == '\0')
 165                 return (-1);
 166
 167         /*
 168          * If the master password file doesn't exist, the system is hosed.
 169          * Might as well try to build one.  Set the close-on-exec bit so
 170          * that users can't get at the encrypted passwords while editing.
 171          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 172          */
 173         for (;;) {
 174                 struct stat st;
 175
 176                 lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 177                 if (lockfd == -1) {
 178                         if (errno == EWOULDBLOCK) {
 179                                 errx(1, "the password db file is busy");
 180                         } else {
 181                                 err(1, "could not lock the passwd file: ");
 182                         }
 183                 }
 184
 185                 /*
 186                  * If the password file was replaced while we were trying to
 187                  * get the lock, our hardlink count will be 0 and we have to
 188                  * close and retry.
 189                  */
 190                 if (fstat(lockfd, &st) == -1)
 191                         err(1, "fstat() failed: ");
 192                 if (st.st_nlink != 0)
 193                         break;
 194                 close(lockfd);
 195                 lockfd = -1;
 196         }
 197         return (lockfd);
 198 }
 199
 200 /*
 201  * Create and open a presumably safe temp file for editing the password
 202  * data, and copy the master password file into it.
 203  */
 204 int
 205 pw_tmp(int mfd)
 206 {
 207         char buf[8192];
 208         ssize_t nr;
 209         const char *p;
 210         int tfd;
 211
 212         if (*masterpasswd == '\0')
 213                 return (-1);
 214         if ((p = strrchr(masterpasswd, '/')))
 215                 ++p;
 216         else
 217                 p = masterpasswd;
 218         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 219                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 220                 errno = ENAMETOOLONG;
 221                 return (-1);
 222         }
 223         if ((tfd = mkstemp(tempname)) == -1)
 224                 return (-1);
 225         if (mfd != -1) {
 226                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 227                         if (write(tfd, buf, (size_t)nr) != nr)
 228                                 break;
 229                 if (nr != 0) {
 230                         unlink(tempname);
 231                         *tempname = '\0';
 232                         close(tfd);
 233                         return (-1);
 234                 }
 235         }
 236         return (tfd);
 237 }
 238
 239 /*
 240  * Regenerate the password database.
 241  */
 242 int
 243 pw_mkdb(const char *user)
 244 {
 245         int pstat;
 246         pid_t pid;
 247
 248         (void)fflush(stderr);
 249         switch ((pid = fork())) {
 250         case -1:
 251                 return (-1);
 252         case 0:
 253                 /* child */
 254                 if (user == NULL)
 255                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 256                             "-d", passwd_dir, tempname, NULL);
 257                 else
 258                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 259                             "-d", passwd_dir, "-u", user, tempname,
 260                             NULL);
 261                 _exit(1);
 262                 /* NOTREACHED */
 263         default:
 264                 /* parent */
 265                 break;
 266         }
 267         if (waitpid(pid, &pstat, 0) == -1)
 268                 return (-1);
 269         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 270                 return (0);
 271         errno = 0;
 272         return (-1);
 273 }
 274
 275 /*
 276  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 277  * if it was not.
 278  */
 279 int
 280 pw_edit(int notsetuid)
 281 {
 282         struct sigaction sa, sa_int, sa_quit;
 283         sigset_t oldsigset, nsigset;
 284         struct stat st1, st2;
 285         const char *editor;
 286         int pstat;
 287
 288         if ((editor = getenv("EDITOR")) == NULL)
 289                 editor = _PATH_VI;
 290         if (stat(tempname, &st1) == -1)
 291                 return (-1);
 292         sa.sa_handler = SIG_IGN;
 293         sigemptyset(&sa.sa_mask);
 294         sa.sa_flags = 0;
 295         sigaction(SIGINT, &sa, &sa_int);
 296         sigaction(SIGQUIT, &sa, &sa_quit);
 297         sigemptyset(&nsigset);
 298         sigaddset(&nsigset, SIGCHLD);
 299         sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
 300         switch ((editpid = fork())) {
 301         case -1:
 302                 return (-1);
 303         case 0:
 304                 sigaction(SIGINT, &sa_int, NULL);
 305                 sigaction(SIGQUIT, &sa_quit, NULL);
 306                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 307                 if (notsetuid) {
 308                         (void)setgid(getgid());
 309                         (void)setuid(getuid());
 310                 }
 311                 errno = 0;
 312                 execlp(editor, basename(editor), tempname, NULL);
 313                 _exit(errno);
 314         default:
 315                 /* parent */
 316                 break;
 317         }
 318         for (;;) {
 319                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 320                         if (errno == EINTR)
 321                                 continue;
 322                         unlink(tempname);
 323                         editpid = -1;
 324                         break;
 325                 } else if (WIFSTOPPED(pstat)) {
 326                         raise(WSTOPSIG(pstat));
 327                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 328                         editpid = -1;
 329                         break;
 330                 } else {
 331                         unlink(tempname);
 332                         editpid = -1;
 333                         break;
 334                 }
 335         }
 336         sigaction(SIGINT, &sa_int, NULL);
 337         sigaction(SIGQUIT, &sa_quit, NULL);
 338         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 339         if (stat(tempname, &st2) == -1)
 340                 return (-1);
 341         return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
 342             st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
 343 }
 344
 345 /*
 346  * Clean up.  Preserve errno for the caller's convenience.
 347  */
 348 void
 349 pw_fini(void)
 350 {
 351         int serrno, status;
 352
 353         if (!initialized)
 354                 return;
 355         initialized = 0;
 356         serrno = errno;
 357         if (editpid != -1) {
 358                 kill(editpid, SIGTERM);
 359                 kill(editpid, SIGCONT);
 360                 waitpid(editpid, &status, 0);
 361                 editpid = -1;
 362         }
 363         if (*tempname != '\0') {
 364                 unlink(tempname);
 365                 *tempname = '\0';
 366         }
 367         if (lockfd != -1)
 368                 close(lockfd);
 369         errno = serrno;
 370 }
 371
 372 /*
 373  * Compares two struct pwds.
 374  */
 375 int
 376 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 377 {
 378         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 379             pw1->pw_uid == pw2->pw_uid &&
 380             pw1->pw_gid == pw2->pw_gid &&
 381             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 382             pw1->pw_change == pw2->pw_change &&
 383             pw1->pw_expire == pw2->pw_expire &&
 384             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 385             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 386             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 387 }
 388
 389 /*
 390  * Make a passwd line out of a struct passwd.
 391  */
 392 char *
 393 pw_make(const struct passwd *pw)
 394 {
 395         char *line;
 396
 397         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 398             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 399             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 400             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 401         return (line);
 402 }
 403
 404 /*
 405  * Make a passwd line (in v7 format) out of a struct passwd
 406  */
 407 char *
 408 pw_make_v7(const struct passwd *pw)
 409 {
 410         char *line;
 411
 412         asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
 413             (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 414             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 415         return (line);
 416 }
 417
 418 /*
 419  * Copy password file from one descriptor to another, replacing, deleting
 420  * or adding a single record on the way.
 421  */
 422 int
 423 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 424 {
 425         char buf[8192], *end, *line, *p, *q, *r, t;
 426         struct passwd *fpw;
 427         const struct passwd *spw;
 428         size_t len;
 429         int eof, readlen;
 430
 431         if (old_pw == NULL && pw == NULL)
 432                         return (-1);
 433
 434         spw = old_pw;
 435         /* deleting a user */
 436         if (pw == NULL) {
 437                 line = NULL;
 438         } else {
 439         if ((line = pw_make(pw)) == NULL)
 440                 return (-1);
 441         }
 442
 443         /* adding a user */
 444         if (spw == NULL)
 445                 spw = pw;
 446
 447         eof = 0;
 448         len = 0;
 449         p = q = end = buf;
 450         for (;;) {
 451                 /* find the end of the current line */
 452                 for (p = q; q < end && *q != '\0'; ++q)
 453                         if (*q == '\n')
 454                                 break;
 455
 456                 /* if we don't have a complete line, fill up the buffer */
 457                 if (q >= end) {
 458                         if (eof)
 459                                 break;
 460                         if ((size_t)(q - p) >= sizeof(buf)) {
 461                                 warnx("passwd line too long");
 462                                 errno = EINVAL; /* hack */
 463                                 goto err;
 464                         }
 465                         if (p < end) {
 466                                 q = memmove(buf, p, end - p);
 467                                 end -= p - buf;
 468                         } else {
 469                                 p = q = end = buf;
 470                         }
 471                         readlen = read(ffd, end, sizeof(buf) - (end - buf));
 472                         if (readlen == -1)
 473                                 goto err;
 474                         else
 475                                 len = (size_t)readlen;
 476                         if (len == 0 && p == buf)
 477                                 break;
 478                         end += len;
 479                         len = end - buf;
 480                         if (len < (ssize_t)sizeof(buf)) {
 481                                 eof = 1;
 482                                 if (len > 0 && buf[len - 1] != '\n')
 483                                         ++len, *end++ = '\n';
 484                         }
 485                         continue;
 486                 }
 487
 488                 /* is it a blank line or a comment? */
 489                 for (r = p; r < q && isspace(*r); ++r)
 490                         /* nothing */ ;
 491                 if (r == q || *r == '#') {
 492                         /* yep */
 493                         if (write(tfd, p, q - p + 1) != q - p + 1)
 494                                 goto err;
 495                         ++q;
 496                         continue;
 497                 }
 498
 499                 /* is it the one we're looking for? */
 500
 501                 t = *q;
 502                 *q = '\0';
 503
 504                 fpw = pw_scan(r, PWSCAN_MASTER);
 505
 506                 /*
 507                  * fpw is either the struct passwd for the current line,
 508                  * or NULL if the line is malformed.
 509                  */
 510
 511                 *q = t;
 512                 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
 513                         /* nope */
 514                         if (fpw != NULL)
 515                                 free(fpw);
 516                         if (write(tfd, p, q - p + 1) != q - p + 1)
 517                                 goto err;
 518                         ++q;
 519                         continue;
 520                 }
 521                 if (old_pw && !pw_equal(fpw, old_pw)) {
 522                         warnx("entry inconsistent");
 523                         free(fpw);
 524                         errno = EINVAL; /* hack */
 525                         goto err;
 526                 }
 527                 free(fpw);
 528
 529                 /* it is, replace or remove it */
 530                 if (line != NULL) {
 531                 len = strlen(line);
 532                 if (write(tfd, line, len) != (int)len)
 533                         goto err;
 534                 } else {
 535                         /* when removed, avoid the \n */
 536                         q++;
 537                 }
 538                 /* we're done, just copy the rest over */
 539                 for (;;) {
 540                         if (write(tfd, q, end - q) != end - q)
 541                                 goto err;
 542                         q = buf;
 543                         readlen = read(ffd, buf, sizeof(buf));
 544                         if (readlen == 0)
 545                                 break;
 546                         else
 547                                 len = (size_t)readlen;
 548                         if (readlen == -1)
 549                                 goto err;
 550                         end = buf + len;
 551                 }
 552                 goto done;
 553         }
 554
 555         /* if we got here, we didn't find the old entry */
 556         if (line == NULL) {
 557                 errno = ENOENT;
 558                 goto err;
 559         }
 560         len = strlen(line);
 561         if ((size_t)write(tfd, line, len) != len ||
 562             write(tfd, "\n", 1) != 1)
 563                 goto err;
 564  done:
 565         if (line != NULL)
 566                 free(line);
 567         return (0);
 568  err:
 569         if (line != NULL)
 570                 free(line);
 571         return (-1);
 572 }
 573
 574 /*
 575  * Return the current value of tempname.
 576  */
 577 const char *
 578 pw_tempname(void)
 579 {
 580
 581         return (tempname);
 582 }
 583
 584 /*
 585  * Duplicate a struct passwd.
 586  */
 587 struct passwd *
 588 pw_dup(const struct passwd *pw)
 589 {
 590         char *dst;
 591         struct passwd *npw;
 592         ssize_t len;
 593
 594         len = sizeof(*npw);
 595         if (pw->pw_name != NULL)
 596                 len += strlen(pw->pw_name) + 1;
 597         if (pw->pw_passwd != NULL)
 598                 len += strlen(pw->pw_passwd) + 1;
 599         if (pw->pw_class != NULL)
 600                 len += strlen(pw->pw_class) + 1;
 601         if (pw->pw_gecos != NULL)
 602                 len += strlen(pw->pw_gecos) + 1;
 603         if (pw->pw_dir != NULL)
 604                 len += strlen(pw->pw_dir) + 1;
 605         if (pw->pw_shell != NULL)
 606                 len += strlen(pw->pw_shell) + 1;
 607         if ((npw = malloc((size_t)len)) == NULL)
 608                 return (NULL);
 609         memcpy(npw, pw, sizeof(*npw));
 610         dst = (char *)npw + sizeof(*npw);
 611         if (pw->pw_name != NULL) {
 612                 npw->pw_name = dst;
 613                 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
 614         }
 615         if (pw->pw_passwd != NULL) {
 616                 npw->pw_passwd = dst;
 617                 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
 618         }
 619         if (pw->pw_class != NULL) {
 620                 npw->pw_class = dst;
 621                 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
 622         }
 623         if (pw->pw_gecos != NULL) {
 624                 npw->pw_gecos = dst;
 625                 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
 626         }
 627         if (pw->pw_dir != NULL) {
 628                 npw->pw_dir = dst;
 629                 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
 630         }
 631         if (pw->pw_shell != NULL) {
 632                 npw->pw_shell = dst;
 633                 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
 634         }
 635         return (npw);
 636 }
 637
 638 #include "pw_scan.h"
 639
 640 /*
 641  * Wrapper around an internal libc function
 642  */
 643 struct passwd *
 644 pw_scan(const char *line, int flags)
 645 {
 646         struct passwd pw, *ret;
 647         char *bp;
 648
 649         if ((bp = strdup(line)) == NULL)
 650                 return (NULL);
 651         if (!__pw_scan(bp, &pw, flags)) {
 652                 free(bp);
 653                 return (NULL);
 654         }
 655         ret = pw_dup(&pw);
 656         free(bp);
 657         return (ret);
 658 }