libutil/pw_util.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 2002 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * Portions of this software were developed for the FreeBSD Project by
   8  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   9  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  10  * ("CBOSS"), as part of the DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Berkeley and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  */
  40
  41 #ifndef lint
  42 #if 0
  43 static const char sccsid[] = "@(#)pw_util.c     8.3 (Berkeley) 4/2/94";
  44 #endif
  45 static const char rcsid[] =
  46   "$FreeBSD$";
  47 #endif /* not lint */
  48
  49 /*
  50  * This file is used by all the "password" programs; vipw(8), chpass(1),
  51  * and passwd(1).
  52  */
  53
  54 #include <sys/param.h>
  55 #include <sys/errno.h>
  56 #include <sys/time.h>
  57 #include <sys/resource.h>
  58 #include <sys/stat.h>
  59 #include <sys/wait.h>
  60
  61 #include <ctype.h>
  62 #include <err.h>
  63 #include <fcntl.h>
  64 #include <inttypes.h>
  65 #include <libgen.h>
  66 #include <paths.h>
  67 #include <pwd.h>
  68 #include <signal.h>
  69 #include <stdio.h>
  70 #include <stdlib.h>
  71 #include <string.h>
  72 #include <unistd.h>
  73
  74 #include <libutil.h>
  75
  76 static pid_t editpid = -1;
  77 static int lockfd = -1;
  78 static char masterpasswd[PATH_MAX];
  79 static char passwd_dir[PATH_MAX];
  80 static char tempname[PATH_MAX];
  81 static int initialized;
  82
  83 #if 0
  84 void
  85 pw_cont(int sig)
  86 {
  87
  88         if (editpid != -1)
  89                 kill(editpid, sig);
  90 }
  91 #endif
  92
  93 /*
  94  * Initialize statics and set limits, signals & umask to try to avoid
  95  * interruptions, crashes etc. that might expose passord data.
  96  */
  97 int
  98 pw_init(const char *dir, const char *master)
  99 {
 100 #if 0
 101         struct rlimit rlim;
 102 #endif
 103
 104         if (dir == NULL) {
 105                 strcpy(passwd_dir, _PATH_ETC);
 106         } else {
 107                 if (strlen(dir) >= sizeof(passwd_dir)) {
 108                         errno = ENAMETOOLONG;
 109                         return (-1);
 110                 }
 111                 strcpy(passwd_dir, dir);
 112         }
 113
 114         if (master == NULL) {
 115                 if (dir == NULL) {
 116                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 117                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 118                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 119                         errno = ENAMETOOLONG;
 120                         return (-1);
 121                 }
 122         } else {
 123                 if (strlen(master) >= sizeof(masterpasswd)) {
 124                         errno = ENAMETOOLONG;
 125                         return (-1);
 126                 }
 127                 strcpy(masterpasswd, master);
 128         }
 129
 130         /*
 131          * The code that follows is extremely disruptive to the calling
 132          * process, and is therefore disabled until someone can conceive
 133          * of a realistic scenario where it would fend off a compromise.
 134          * Race conditions concerning the temporary files can be guarded
 135          * against in other ways than masking signals (by checking stat(2)
 136          * results after creation).
 137          */
 138 #if 0
 139         /* Unlimited resource limits. */
 140         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 141         (void)setrlimit(RLIMIT_CPU, &rlim);
 142         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 143         (void)setrlimit(RLIMIT_STACK, &rlim);
 144         (void)setrlimit(RLIMIT_DATA, &rlim);
 145         (void)setrlimit(RLIMIT_RSS, &rlim);
 146
 147         /* Don't drop core (not really necessary, but GP's). */
 148         rlim.rlim_cur = rlim.rlim_max = 0;
 149         (void)setrlimit(RLIMIT_CORE, &rlim);
 150
 151         /* Turn off signals. */
 152         (void)signal(SIGALRM, SIG_IGN);
 153         (void)signal(SIGHUP, SIG_IGN);
 154         (void)signal(SIGINT, SIG_IGN);
 155         (void)signal(SIGPIPE, SIG_IGN);
 156         (void)signal(SIGQUIT, SIG_IGN);
 157         (void)signal(SIGTERM, SIG_IGN);
 158         (void)signal(SIGCONT, pw_cont);
 159
 160         /* Create with exact permissions. */
 161         (void)umask(0);
 162 #endif
 163         initialized = 1;
 164         return (0);
 165 }
 166
 167 /*
 168  * Lock the master password file.
 169  */
 170 int
 171 pw_lock(void)
 172 {
 173
 174         if (*masterpasswd == '\0')
 175                 return (-1);
 176
 177         /*
 178          * If the master password file doesn't exist, the system is hosed.
 179          * Might as well try to build one.  Set the close-on-exec bit so
 180          * that users can't get at the encrypted passwords while editing.
 181          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 182          */
 183         for (;;) {
 184                 struct stat st;
 185
 186                 lockfd = open(masterpasswd, O_RDONLY, 0);
 187                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 188                         err(1, "%s", masterpasswd);
 189                 /* XXX vulnerable to race conditions */
 190                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 191                         if (errno == EWOULDBLOCK) {
 192                                 errx(1, "the password db file is busy");
 193                         } else {
 194                                 err(1, "could not lock the passwd file: ");
 195                         }
 196                 }
 197
 198                 /*
 199                  * If the password file was replaced while we were trying to
 200                  * get the lock, our hardlink count will be 0 and we have to
 201                  * close and retry.
 202                  */
 203                 if (fstat(lockfd, &st) == -1)
 204                         err(1, "fstat() failed: ");
 205                 if (st.st_nlink != 0)
 206                         break;
 207                 close(lockfd);
 208                 lockfd = -1;
 209         }
 210         return (lockfd);
 211 }
 212
 213 /*
 214  * Create and open a presumably safe temp file for editing the password
 215  * data, and copy the master password file into it.
 216  */
 217 int
 218 pw_tmp(int mfd)
 219 {
 220         char buf[8192];
 221         ssize_t nr;
 222         const char *p;
 223         int tfd;
 224
 225         if (*masterpasswd == '\0')
 226                 return (-1);
 227         if ((p = strrchr(masterpasswd, '/')))
 228                 ++p;
 229         else
 230                 p = masterpasswd;
 231         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 232                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 233                 errno = ENAMETOOLONG;
 234                 return (-1);
 235         }
 236         if ((tfd = mkstemp(tempname)) == -1)
 237                 return (-1);
 238         if (mfd != -1) {
 239                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 240                         if (write(tfd, buf, (size_t)nr) != nr)
 241                                 break;
 242                 if (nr != 0) {
 243                         unlink(tempname);
 244                         *tempname = '\0';
 245                         close(tfd);
 246                         return (-1);
 247                 }
 248         }
 249         return (tfd);
 250 }
 251
 252 /*
 253  * Regenerate the password database.
 254  */
 255 int
 256 pw_mkdb(const char *user)
 257 {
 258         int pstat;
 259         pid_t pid;
 260
 261         (void)fflush(stderr);
 262         switch ((pid = fork())) {
 263         case -1:
 264                 return (-1);
 265         case 0:
 266                 /* child */
 267                 if (user == NULL)
 268                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 269                             "-d", passwd_dir, tempname, NULL);
 270                 else
 271                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 272                             "-d", passwd_dir, "-u", user, tempname, NULL);
 273                 _exit(1);
 274                 /* NOTREACHED */
 275         default:
 276                 /* parent */
 277                 break;
 278         }
 279         if (waitpid(pid, &pstat, 0) == -1)
 280                 return (-1);
 281         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 282                 return (0);
 283         errno = 0;
 284         return (-1);
 285 }
 286
 287 /*
 288  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 289  * if it was not.
 290  */
 291 int
 292 pw_edit(int notsetuid)
 293 {
 294         struct sigaction sa, sa_int, sa_quit;
 295         sigset_t oldsigset, sigset;
 296         struct stat st1, st2;
 297         const char *editor;
 298         int pstat;
 299
 300         if ((editor = getenv("EDITOR")) == NULL)
 301                 editor = _PATH_VI;
 302         if (stat(tempname, &st1) == -1)
 303                 return (-1);
 304         sa.sa_handler = SIG_IGN;
 305         sigemptyset(&sa.sa_mask);
 306         sa.sa_flags = 0;
 307         sigaction(SIGINT, &sa, &sa_int);
 308         sigaction(SIGQUIT, &sa, &sa_quit);
 309         sigemptyset(&sigset);
 310         sigaddset(&sigset, SIGCHLD);
 311         sigprocmask(SIG_BLOCK, &sigset, &oldsigset);
 312         switch ((editpid = fork())) {
 313         case -1:
 314                 return (-1);
 315         case 0:
 316                 sigaction(SIGINT, &sa_int, NULL);
 317                 sigaction(SIGQUIT, &sa_quit, NULL);
 318                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 319                 if (notsetuid) {
 320                         (void)setgid(getgid());
 321                         (void)setuid(getuid());
 322                 }
 323                 errno = 0;
 324                 execlp(editor, basename(editor), tempname, NULL);
 325                 _exit(errno);
 326         default:
 327                 /* parent */
 328                 break;
 329         }
 330         for (;;) {
 331                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 332                         if (errno == EINTR)
 333                                 continue;
 334                         unlink(tempname);
 335                         editpid = -1;
 336                         break;
 337                 } else if (WIFSTOPPED(pstat)) {
 338                         raise(WSTOPSIG(pstat));
 339                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 340                         editpid = -1;
 341                         break;
 342                 } else {
 343                         unlink(tempname);
 344                         editpid = -1;
 345                         break;
 346                 }
 347         }
 348         sigaction(SIGINT, &sa_int, NULL);
 349         sigaction(SIGQUIT, &sa_quit, NULL);
 350         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 351         if (stat(tempname, &st2) == -1)
 352                 return (-1);
 353         return (st1.st_mtime != st2.st_mtime);
 354 }
 355
 356 /*
 357  * Clean up.  Preserve errno for the caller's convenience.
 358  */
 359 void
 360 pw_fini(void)
 361 {
 362         int serrno, status;
 363
 364         if (!initialized)
 365                 return;
 366         initialized = 0;
 367         serrno = errno;
 368         if (editpid != -1) {
 369                 kill(editpid, SIGTERM);
 370                 kill(editpid, SIGCONT);
 371                 waitpid(editpid, &status, 0);
 372                 editpid = -1;
 373         }
 374         if (*tempname != '\0') {
 375                 unlink(tempname);
 376                 *tempname = '\0';
 377         }
 378         if (lockfd != -1)
 379                 close(lockfd);
 380         errno = serrno;
 381 }
 382
 383 /*
 384  * Compares two struct pwds.
 385  */
 386 int
 387 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 388 {
 389         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 390             pw1->pw_uid == pw2->pw_uid &&
 391             pw1->pw_gid == pw2->pw_gid &&
 392             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 393             pw1->pw_change == pw2->pw_change &&
 394             pw1->pw_expire == pw2->pw_expire &&
 395             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 396             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 397             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 398 }
 399
 400 /*
 401  * Make a passwd line out of a struct passwd.
 402  */
 403 char *
 404 pw_make(const struct passwd *pw)
 405 {
 406         char *line;
 407
 408         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 409             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 410             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 411             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 412         return line;
 413 }
 414
 415 /*
 416  * Copy password file from one descriptor to another, replacing or adding
 417  * a single record on the way.
 418  */
 419 int
 420 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 421 {
 422         char buf[8192], *end, *line, *p, *q, *r, t;
 423         struct passwd *fpw;
 424         size_t len;
 425         int eof, readlen;
 426
 427         if ((line = pw_make(pw)) == NULL)
 428                 return (-1);
 429
 430         eof = 0;
 431         len = 0;
 432         p = q = end = buf;
 433         for (;;) {
 434                 /* find the end of the current line */
 435                 for (p = q; q < end && *q != '\0'; ++q)
 436                         if (*q == '\n')
 437                                 break;
 438
 439                 /* if we don't have a complete line, fill up the buffer */
 440                 if (q >= end) {
 441                         if (eof)
 442                                 break;
 443                         if ((size_t)(q - p) >= sizeof(buf)) {
 444                                 warnx("passwd line too long");
 445                                 errno = EINVAL; /* hack */
 446                                 goto err;
 447                         }
 448                         if (p < end) {
 449                                 q = memmove(buf, p, end - p);
 450                                 end -= p - buf;
 451                         } else {
 452                                 p = q = end = buf;
 453                         }
 454                         readlen = read(ffd, end, sizeof(buf) - (end - buf));
 455                         if (readlen == -1)
 456                                 goto err;
 457                         else
 458                                 len = (size_t)readlen;
 459                         if (len == 0 && p == buf)
 460                                 break;
 461                         end += len;
 462                         len = end - buf;
 463                         if (len < (ssize_t)sizeof(buf)) {
 464                                 eof = 1;
 465                                 if (len > 0 && buf[len - 1] != '\n')
 466                                         ++len, *end++ = '\n';
 467                         }
 468                         continue;
 469                 }
 470
 471                 /* is it a blank line or a comment? */
 472                 for (r = p; r < q && isspace(*r); ++r)
 473                         /* nothing */ ;
 474                 if (r == q || *r == '#') {
 475                         /* yep */
 476                         if (write(tfd, p, q - p + 1) != q - p + 1)
 477                                 goto err;
 478                         ++q;
 479                         continue;
 480                 }
 481
 482                 /* is it the one we're looking for? */
 483                 t = *q;
 484                 *q = '\0';
 485                 fpw = pw_scan(r, PWSCAN_MASTER);
 486                 *q = t;
 487                 if (strcmp(fpw->pw_name, pw->pw_name) != 0) {
 488                         /* nope */
 489                         free(fpw);
 490                         if (write(tfd, p, q - p + 1) != q - p + 1)
 491                                 goto err;
 492                         ++q;
 493                         continue;
 494                 }
 495                 if (old_pw && !pw_equal(fpw, old_pw)) {
 496                         warnx("entry inconsistent");
 497                         free(fpw);
 498                         errno = EINVAL; /* hack */
 499                         goto err;
 500                 }
 501                 free(fpw);
 502
 503                 /* it is, replace it */
 504                 len = strlen(line);
 505                 if (write(tfd, line, len) != (int)len)
 506                         goto err;
 507
 508                 /* we're done, just copy the rest over */
 509                 for (;;) {
 510                         if (write(tfd, q, end - q) != end - q)
 511                                 goto err;
 512                         q = buf;
 513                         readlen = read(ffd, buf, sizeof(buf));
 514                         if (readlen == 0)
 515                                 break;
 516                         else
 517                                 len = (size_t)readlen;
 518                         if (readlen == -1)
 519                                 goto err;
 520                         end = buf + len;
 521                 }
 522                 goto done;
 523         }
 524
 525         /* if we got here, we have a new entry */
 526         len = strlen(line);
 527         if ((size_t)write(tfd, line, len) != len ||
 528             write(tfd, "\n", 1) != 1)
 529                 goto err;
 530  done:
 531         free(line);
 532         return (0);
 533  err:
 534         free(line);
 535         return (-1);
 536 }
 537
 538 /*
 539  * Return the current value of tempname.
 540  */
 541 const char *
 542 pw_tempname(void)
 543 {
 544
 545         return (tempname);
 546 }
 547
 548 /*
 549  * Duplicate a struct passwd.
 550  */
 551 struct passwd *
 552 pw_dup(const struct passwd *pw)
 553 {
 554         struct passwd *npw;
 555         ssize_t len;
 556
 557         len = sizeof(*npw) +
 558             (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) +
 559             (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) +
 560             (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) +
 561             (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) +
 562             (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) +
 563             (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0);
 564         if ((npw = malloc((size_t)len)) == NULL)
 565                 return (NULL);
 566         memcpy(npw, pw, sizeof(*npw));
 567         len = sizeof(*npw);
 568         if (pw->pw_name) {
 569                 npw->pw_name = ((char *)npw) + len;
 570                 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1;
 571         }
 572         if (pw->pw_passwd) {
 573                 npw->pw_passwd = ((char *)npw) + len;
 574                 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1;
 575         }
 576         if (pw->pw_class) {
 577                 npw->pw_class = ((char *)npw) + len;
 578                 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1;
 579         }
 580         if (pw->pw_gecos) {
 581                 npw->pw_gecos = ((char *)npw) + len;
 582                 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1;
 583         }
 584         if (pw->pw_dir) {
 585                 npw->pw_dir = ((char *)npw) + len;
 586                 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1;
 587         }
 588         if (pw->pw_shell) {
 589                 npw->pw_shell = ((char *)npw) + len;
 590                 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1;
 591         }
 592         return (npw);
 593 }
 594
 595 #include "pw_scan.h"
 596
 597 /*
 598  * Wrapper around an internal libc function
 599  */
 600 struct passwd *
 601 pw_scan(const char *line, int flags)
 602 {
 603         struct passwd pw, *ret;
 604         char *bp;
 605
 606         if ((bp = strdup(line)) == NULL)
 607                 return (NULL);
 608         if (!__pw_scan(bp, &pw, flags)) {
 609                 free(bp);
 610                 return (NULL);
 611         }
 612         ret = pw_dup(&pw);
 613         free(bp);
 614         return (ret);
 615 }