libutil/pw_util.c

   1 /*--
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1990, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  * Copyright (c) 2002 Networks Associates Technology, Inc.
   7  * All rights reserved.
   8  *
   9  * Portions of this software were developed for the FreeBSD Project by
  10  * ThinkSec AS and NAI Labs, the Security Research Division of Network
  11  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  12  * ("CBOSS"), as part of the DARPA CHATS research program.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions
  16  * are met:
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  * 2. Redistributions in binary form must reproduce the above copyright
  20  *    notice, this list of conditions and the following disclaimer in the
  21  *    documentation and/or other materials provided with the distribution.
  22  * 3. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  */
  38
  39 #include <sys/cdefs.h>
  40 __FBSDID("$FreeBSD$");
  41 __SCCSID("@(#)pw_util.c 8.3 (Berkeley) 4/2/94");
  42
  43 /*
  44  * This file is used by all the "password" programs; vipw(8), chpass(1),
  45  * and passwd(1).
  46  */
  47
  48 #include <sys/param.h>
  49 #include <sys/errno.h>
  50 #include <sys/time.h>
  51 #include <sys/resource.h>
  52 #include <sys/stat.h>
  53 #include <sys/wait.h>
  54
  55 #include <ctype.h>
  56 #include <err.h>
  57 #include <fcntl.h>
  58 #include <inttypes.h>
  59 #include <paths.h>
  60 #include <pwd.h>
  61 #include <signal.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <unistd.h>
  66
  67 #include "libutil.h"
  68
  69 static pid_t editpid = -1;
  70 static int lockfd = -1;
  71 static char masterpasswd[PATH_MAX];
  72 static char passwd_dir[PATH_MAX];
  73 static char tempname[PATH_MAX];
  74 static int initialized;
  75
  76 #if 0
  77 void
  78 pw_cont(int sig)
  79 {
  80
  81         if (editpid != -1)
  82                 kill(editpid, sig);
  83 }
  84 #endif
  85
  86 /*
  87  * Initialize statics and set limits, signals & umask to try to avoid
  88  * interruptions, crashes etc. that might expose passord data.
  89  */
  90 int
  91 pw_init(const char *dir, const char *master)
  92 {
  93 #if 0
  94         struct rlimit rlim;
  95 #endif
  96
  97         if (dir == NULL) {
  98                 strcpy(passwd_dir, _PATH_ETC);
  99         } else {
 100                 if (strlen(dir) >= sizeof(passwd_dir)) {
 101                         errno = ENAMETOOLONG;
 102                         return (-1);
 103                 }
 104                 strcpy(passwd_dir, dir);
 105         }
 106
 107         if (master == NULL) {
 108                 if (dir == NULL) {
 109                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 110                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 111                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 112                         errno = ENAMETOOLONG;
 113                         return (-1);
 114                 }
 115         } else {
 116                 if (strlen(master) >= sizeof(masterpasswd)) {
 117                         errno = ENAMETOOLONG;
 118                         return (-1);
 119                 }
 120                 strcpy(masterpasswd, master);
 121         }
 122
 123         /*
 124          * The code that follows is extremely disruptive to the calling
 125          * process, and is therefore disabled until someone can conceive
 126          * of a realistic scenario where it would fend off a compromise.
 127          * Race conditions concerning the temporary files can be guarded
 128          * against in other ways than masking signals (by checking stat(2)
 129          * results after creation).
 130          */
 131 #if 0
 132         /* Unlimited resource limits. */
 133         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 134         (void)setrlimit(RLIMIT_CPU, &rlim);
 135         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 136         (void)setrlimit(RLIMIT_STACK, &rlim);
 137         (void)setrlimit(RLIMIT_DATA, &rlim);
 138         (void)setrlimit(RLIMIT_RSS, &rlim);
 139
 140         /* Don't drop core (not really necessary, but GP's). */
 141         rlim.rlim_cur = rlim.rlim_max = 0;
 142         (void)setrlimit(RLIMIT_CORE, &rlim);
 143
 144         /* Turn off signals. */
 145         (void)signal(SIGALRM, SIG_IGN);
 146         (void)signal(SIGHUP, SIG_IGN);
 147         (void)signal(SIGINT, SIG_IGN);
 148         (void)signal(SIGPIPE, SIG_IGN);
 149         (void)signal(SIGQUIT, SIG_IGN);
 150         (void)signal(SIGTERM, SIG_IGN);
 151         (void)signal(SIGCONT, pw_cont);
 152
 153         /* Create with exact permissions. */
 154         (void)umask(0);
 155 #endif
 156         initialized = 1;
 157         return (0);
 158 }
 159
 160 /*
 161  * Lock the master password file.
 162  */
 163 int
 164 pw_lock(void)
 165 {
 166
 167         if (*masterpasswd == '\0')
 168                 return (-1);
 169
 170         /*
 171          * If the master password file doesn't exist, the system is hosed.
 172          * Might as well try to build one.  Set the close-on-exec bit so
 173          * that users can't get at the encrypted passwords while editing.
 174          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 175          */
 176         for (;;) {
 177                 struct stat st;
 178
 179                 lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 180                 if (lockfd == -1) {
 181                         if (errno == EWOULDBLOCK) {
 182                                 errx(1, "the password db file is busy");
 183                         } else {
 184                                 err(1, "could not lock the passwd file: ");
 185                         }
 186                 }
 187
 188                 /*
 189                  * If the password file was replaced while we were trying to
 190                  * get the lock, our hardlink count will be 0 and we have to
 191                  * close and retry.
 192                  */
 193                 if (fstat(lockfd, &st) == -1)
 194                         err(1, "fstat() failed: ");
 195                 if (st.st_nlink != 0)
 196                         break;
 197                 close(lockfd);
 198                 lockfd = -1;
 199         }
 200         return (lockfd);
 201 }
 202
 203 /*
 204  * Create and open a presumably safe temp file for editing the password
 205  * data, and copy the master password file into it.
 206  */
 207 int
 208 pw_tmp(int mfd)
 209 {
 210         char buf[8192];
 211         ssize_t nr;
 212         const char *p;
 213         int tfd;
 214
 215         if (*masterpasswd == '\0')
 216                 return (-1);
 217         if ((p = strrchr(masterpasswd, '/')))
 218                 ++p;
 219         else
 220                 p = masterpasswd;
 221         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 222                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 223                 errno = ENAMETOOLONG;
 224                 return (-1);
 225         }
 226         if ((tfd = mkostemp(tempname, 0)) == -1)
 227                 return (-1);
 228         if (mfd != -1) {
 229                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 230                         if (write(tfd, buf, (size_t)nr) != nr)
 231                                 break;
 232                 if (nr != 0) {
 233                         unlink(tempname);
 234                         *tempname = '\0';
 235                         close(tfd);
 236                         return (-1);
 237                 }
 238         }
 239         return (tfd);
 240 }
 241
 242 /*
 243  * Regenerate the password database.
 244  */
 245 int
 246 pw_mkdb(const char *user)
 247 {
 248         int pstat;
 249         pid_t pid;
 250
 251         (void)fflush(stderr);
 252         switch ((pid = fork())) {
 253         case -1:
 254                 return (-1);
 255         case 0:
 256                 /* child */
 257                 if (user == NULL)
 258                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 259                             "-d", passwd_dir, tempname, (char *)NULL);
 260                 else
 261                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 262                             "-d", passwd_dir, "-u", user, tempname,
 263                             (char *)NULL);
 264                 _exit(1);
 265                 /* NOTREACHED */
 266         default:
 267                 /* parent */
 268                 break;
 269         }
 270         if (waitpid(pid, &pstat, 0) == -1)
 271                 return (-1);
 272         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 273                 return (0);
 274         errno = 0;
 275         return (-1);
 276 }
 277
 278 /*
 279  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 280  * if it was not.
 281  */
 282 int
 283 pw_edit(int notsetuid)
 284 {
 285         struct sigaction sa, sa_int, sa_quit;
 286         sigset_t oldsigset, nsigset;
 287         struct stat st1, st2;
 288         const char *editor;
 289         int pstat;
 290
 291         if ((editor = getenv("EDITOR")) == NULL)
 292                 editor = _PATH_VI;
 293         if (stat(tempname, &st1) == -1)
 294                 return (-1);
 295         sa.sa_handler = SIG_IGN;
 296         sigemptyset(&sa.sa_mask);
 297         sa.sa_flags = 0;
 298         sigaction(SIGINT, &sa, &sa_int);
 299         sigaction(SIGQUIT, &sa, &sa_quit);
 300         sigemptyset(&nsigset);
 301         sigaddset(&nsigset, SIGCHLD);
 302         sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
 303         switch ((editpid = fork())) {
 304         case -1:
 305                 return (-1);
 306         case 0:
 307                 sigaction(SIGINT, &sa_int, NULL);
 308                 sigaction(SIGQUIT, &sa_quit, NULL);
 309                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 310                 if (notsetuid) {
 311                         (void)setgid(getgid());
 312                         (void)setuid(getuid());
 313                 }
 314                 errno = 0;
 315                 execlp(editor, editor, tempname, (char *)NULL);
 316                 _exit(errno);
 317         default:
 318                 /* parent */
 319                 break;
 320         }
 321         for (;;) {
 322                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 323                         if (errno == EINTR)
 324                                 continue;
 325                         unlink(tempname);
 326                         editpid = -1;
 327                         break;
 328                 } else if (WIFSTOPPED(pstat)) {
 329                         raise(WSTOPSIG(pstat));
 330                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 331                         editpid = -1;
 332                         break;
 333                 } else {
 334                         unlink(tempname);
 335                         editpid = -1;
 336                         break;
 337                 }
 338         }
 339         sigaction(SIGINT, &sa_int, NULL);
 340         sigaction(SIGQUIT, &sa_quit, NULL);
 341         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 342         if (stat(tempname, &st2) == -1)
 343                 return (-1);
 344         return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
 345             st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
 346 }
 347
 348 /*
 349  * Clean up.  Preserve errno for the caller's convenience.
 350  */
 351 void
 352 pw_fini(void)
 353 {
 354         int serrno, status;
 355
 356         if (!initialized)
 357                 return;
 358         initialized = 0;
 359         serrno = errno;
 360         if (editpid != -1) {
 361                 kill(editpid, SIGTERM);
 362                 kill(editpid, SIGCONT);
 363                 waitpid(editpid, &status, 0);
 364                 editpid = -1;
 365         }
 366         if (*tempname != '\0') {
 367                 unlink(tempname);
 368                 *tempname = '\0';
 369         }
 370         if (lockfd != -1)
 371                 close(lockfd);
 372         errno = serrno;
 373 }
 374
 375 /*
 376  * Compares two struct pwds.
 377  */
 378 int
 379 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 380 {
 381         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 382             pw1->pw_uid == pw2->pw_uid &&
 383             pw1->pw_gid == pw2->pw_gid &&
 384             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 385             pw1->pw_change == pw2->pw_change &&
 386             pw1->pw_expire == pw2->pw_expire &&
 387             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 388             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 389             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 390 }
 391
 392 /*
 393  * Make a passwd line out of a struct passwd.
 394  */
 395 char *
 396 pw_make(const struct passwd *pw)
 397 {
 398         char *line;
 399
 400         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 401             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 402             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 403             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 404         return (line);
 405 }
 406
 407 /*
 408  * Make a passwd line (in v7 format) out of a struct passwd
 409  */
 410 char *
 411 pw_make_v7(const struct passwd *pw)
 412 {
 413         char *line;
 414
 415         asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
 416             (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 417             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 418         return (line);
 419 }
 420
 421 /*
 422  * Copy password file from one descriptor to another, replacing, deleting
 423  * or adding a single record on the way.
 424  */
 425 int
 426 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 427 {
 428         char *buf, *end, *line, *p, *q, *r, *tmp;
 429         struct passwd *fpw;
 430         const struct passwd *spw;
 431         size_t len, size;
 432         int eof, readlen;
 433         char t;
 434
 435         if (old_pw == NULL && pw == NULL)
 436                         return (-1);
 437
 438         spw = old_pw;
 439         /* deleting a user */
 440         if (pw == NULL) {
 441                 line = NULL;
 442         } else {
 443                 if ((line = pw_make(pw)) == NULL)
 444                         return (-1);
 445         }
 446
 447         /* adding a user */
 448         if (spw == NULL)
 449                 spw = pw;
 450
 451         /* initialize the buffer */
 452         if ((buf = malloc(size = 1024)) == NULL)
 453                 goto err;
 454
 455         eof = 0;
 456         len = 0;
 457         p = q = end = buf;
 458         for (;;) {
 459                 /* find the end of the current line */
 460                 for (p = q; q < end && *q != '\0'; ++q)
 461                         if (*q == '\n')
 462                                 break;
 463
 464                 /* if we don't have a complete line, fill up the buffer */
 465                 if (q >= end) {
 466                         if (eof)
 467                                 break;
 468                         while ((size_t)(q - p) >= size) {
 469                                 if ((tmp = reallocarray(buf, 2, size)) == NULL) {
 470                                         warnx("passwd line too long");
 471                                         goto err;
 472                                 }
 473                                 p = tmp + (p - buf);
 474                                 q = tmp + (q - buf);
 475                                 end = tmp + (end - buf);
 476                                 buf = tmp;
 477                                 size = size * 2;
 478                         }
 479                         if (p < end) {
 480                                 q = memmove(buf, p, end - p);
 481                                 end -= p - buf;
 482                         } else {
 483                                 p = q = end = buf;
 484                         }
 485                         readlen = read(ffd, end, size - (end - buf));
 486                         if (readlen == -1)
 487                                 goto err;
 488                         else
 489                                 len = (size_t)readlen;
 490                         if (len == 0 && p == buf)
 491                                 break;
 492                         end += len;
 493                         len = end - buf;
 494                         if (len < size) {
 495                                 eof = 1;
 496                                 if (len > 0 && buf[len - 1] != '\n')
 497                                         ++len, *end++ = '\n';
 498                         }
 499                         continue;
 500                 }
 501
 502                 /* is it a blank line or a comment? */
 503                 for (r = p; r < q && isspace(*r); ++r)
 504                         /* nothing */ ;
 505                 if (r == q || *r == '#') {
 506                         /* yep */
 507                         if (write(tfd, p, q - p + 1) != q - p + 1)
 508                                 goto err;
 509                         ++q;
 510                         continue;
 511                 }
 512
 513                 /* is it the one we're looking for? */
 514
 515                 t = *q;
 516                 *q = '\0';
 517
 518                 fpw = pw_scan(r, PWSCAN_MASTER);
 519
 520                 /*
 521                  * fpw is either the struct passwd for the current line,
 522                  * or NULL if the line is malformed.
 523                  */
 524
 525                 *q = t;
 526                 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
 527                         /* nope */
 528                         if (fpw != NULL)
 529                                 free(fpw);
 530                         if (write(tfd, p, q - p + 1) != q - p + 1)
 531                                 goto err;
 532                         ++q;
 533                         continue;
 534                 }
 535                 if (old_pw && !pw_equal(fpw, old_pw)) {
 536                         warnx("entry inconsistent");
 537                         free(fpw);
 538                         errno = EINVAL; /* hack */
 539                         goto err;
 540                 }
 541                 free(fpw);
 542
 543                 /* it is, replace or remove it */
 544                 if (line != NULL) {
 545                         len = strlen(line);
 546                         if (write(tfd, line, len) != (int)len)
 547                                 goto err;
 548                 } else {
 549                         /* when removed, avoid the \n */
 550                         q++;
 551                 }
 552                 /* we're done, just copy the rest over */
 553                 for (;;) {
 554                         if (write(tfd, q, end - q) != end - q)
 555                                 goto err;
 556                         q = buf;
 557                         readlen = read(ffd, buf, size);
 558                         if (readlen == 0)
 559                                 break;
 560                         else
 561                                 len = (size_t)readlen;
 562                         if (readlen == -1)
 563                                 goto err;
 564                         end = buf + len;
 565                 }
 566                 goto done;
 567         }
 568
 569         /* if we got here, we didn't find the old entry */
 570         if (line == NULL) {
 571                 errno = ENOENT;
 572                 goto err;
 573         }
 574         len = strlen(line);
 575         if ((size_t)write(tfd, line, len) != len ||
 576             write(tfd, "\n", 1) != 1)
 577                 goto err;
 578  done:
 579         free(line);
 580         free(buf);
 581         return (0);
 582  err:
 583         free(line);
 584         free(buf);
 585         return (-1);
 586 }
 587
 588 /*
 589  * Return the current value of tempname.
 590  */
 591 const char *
 592 pw_tempname(void)
 593 {
 594
 595         return (tempname);
 596 }
 597
 598 /*
 599  * Duplicate a struct passwd.
 600  */
 601 struct passwd *
 602 pw_dup(const struct passwd *pw)
 603 {
 604         char *dst;
 605         struct passwd *npw;
 606         ssize_t len;
 607
 608         len = sizeof(*npw);
 609         if (pw->pw_name != NULL)
 610                 len += strlen(pw->pw_name) + 1;
 611         if (pw->pw_passwd != NULL)
 612                 len += strlen(pw->pw_passwd) + 1;
 613         if (pw->pw_class != NULL)
 614                 len += strlen(pw->pw_class) + 1;
 615         if (pw->pw_gecos != NULL)
 616                 len += strlen(pw->pw_gecos) + 1;
 617         if (pw->pw_dir != NULL)
 618                 len += strlen(pw->pw_dir) + 1;
 619         if (pw->pw_shell != NULL)
 620                 len += strlen(pw->pw_shell) + 1;
 621         if ((npw = malloc((size_t)len)) == NULL)
 622                 return (NULL);
 623         memcpy(npw, pw, sizeof(*npw));
 624         dst = (char *)npw + sizeof(*npw);
 625         if (pw->pw_name != NULL) {
 626                 npw->pw_name = dst;
 627                 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
 628         }
 629         if (pw->pw_passwd != NULL) {
 630                 npw->pw_passwd = dst;
 631                 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
 632         }
 633         if (pw->pw_class != NULL) {
 634                 npw->pw_class = dst;
 635                 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
 636         }
 637         if (pw->pw_gecos != NULL) {
 638                 npw->pw_gecos = dst;
 639                 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
 640         }
 641         if (pw->pw_dir != NULL) {
 642                 npw->pw_dir = dst;
 643                 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
 644         }
 645         if (pw->pw_shell != NULL) {
 646                 npw->pw_shell = dst;
 647                 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
 648         }
 649         return (npw);
 650 }
 651
 652 #include "pw_scan.h"
 653
 654 /*
 655  * Wrapper around an internal libc function
 656  */
 657 struct passwd *
 658 pw_scan(const char *line, int flags)
 659 {
 660         struct passwd pw, *ret;
 661         char *bp;
 662
 663         if ((bp = strdup(line)) == NULL)
 664                 return (NULL);
 665         if (!__pw_scan(bp, &pw, flags)) {
 666                 free(bp);
 667                 return (NULL);
 668         }
 669         ret = pw_dup(&pw);
 670         free(bp);
 671         return (ret);
 672 }