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 #ifndef lint
  40 #if 0
  41 static const char sccsid[] = "@(#)pw_util.c     8.3 (Berkeley) 4/2/94";
  42 #endif
  43 static const char rcsid[] =
  44   "$FreeBSD$";
  45 #endif /* not lint */
  46
  47 /*
  48  * This file is used by all the "password" programs; vipw(8), chpass(1),
  49  * and passwd(1).
  50  */
  51
  52 #include <sys/param.h>
  53 #include <sys/errno.h>
  54 #include <sys/time.h>
  55 #include <sys/resource.h>
  56 #include <sys/stat.h>
  57 #include <sys/wait.h>
  58
  59 #include <ctype.h>
  60 #include <err.h>
  61 #include <fcntl.h>
  62 #include <inttypes.h>
  63 #include <paths.h>
  64 #include <pwd.h>
  65 #include <signal.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <unistd.h>
  70
  71 #include "libutil.h"
  72
  73 static pid_t editpid = -1;
  74 static int lockfd = -1;
  75 static char masterpasswd[PATH_MAX];
  76 static char passwd_dir[PATH_MAX];
  77 static char tempname[PATH_MAX];
  78 static int initialized;
  79
  80 #if 0
  81 void
  82 pw_cont(int sig)
  83 {
  84
  85         if (editpid != -1)
  86                 kill(editpid, sig);
  87 }
  88 #endif
  89
  90 /*
  91  * Initialize statics and set limits, signals & umask to try to avoid
  92  * interruptions, crashes etc. that might expose passord data.
  93  */
  94 int
  95 pw_init(const char *dir, const char *master)
  96 {
  97 #if 0
  98         struct rlimit rlim;
  99 #endif
 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         /*
 128          * The code that follows is extremely disruptive to the calling
 129          * process, and is therefore disabled until someone can conceive
 130          * of a realistic scenario where it would fend off a compromise.
 131          * Race conditions concerning the temporary files can be guarded
 132          * against in other ways than masking signals (by checking stat(2)
 133          * results after creation).
 134          */
 135 #if 0
 136         /* Unlimited resource limits. */
 137         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 138         (void)setrlimit(RLIMIT_CPU, &rlim);
 139         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 140         (void)setrlimit(RLIMIT_STACK, &rlim);
 141         (void)setrlimit(RLIMIT_DATA, &rlim);
 142         (void)setrlimit(RLIMIT_RSS, &rlim);
 143
 144         /* Don't drop core (not really necessary, but GP's). */
 145         rlim.rlim_cur = rlim.rlim_max = 0;
 146         (void)setrlimit(RLIMIT_CORE, &rlim);
 147
 148         /* Turn off signals. */
 149         (void)signal(SIGALRM, SIG_IGN);
 150         (void)signal(SIGHUP, SIG_IGN);
 151         (void)signal(SIGINT, SIG_IGN);
 152         (void)signal(SIGPIPE, SIG_IGN);
 153         (void)signal(SIGQUIT, SIG_IGN);
 154         (void)signal(SIGTERM, SIG_IGN);
 155         (void)signal(SIGCONT, pw_cont);
 156
 157         /* Create with exact permissions. */
 158         (void)umask(0);
 159 #endif
 160         initialized = 1;
 161         return (0);
 162 }
 163
 164 /*
 165  * Lock the master password file.
 166  */
 167 int
 168 pw_lock(void)
 169 {
 170
 171         if (*masterpasswd == '\0')
 172                 return (-1);
 173
 174         /*
 175          * If the master password file doesn't exist, the system is hosed.
 176          * Might as well try to build one.  Set the close-on-exec bit so
 177          * that users can't get at the encrypted passwords while editing.
 178          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 179          */
 180         for (;;) {
 181                 struct stat st;
 182
 183                 lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
 184                 if (lockfd == -1) {
 185                         if (errno == EWOULDBLOCK) {
 186                                 errx(1, "the password db file is busy");
 187                         } else {
 188                                 err(1, "could not lock the passwd file: ");
 189                         }
 190                 }
 191
 192                 /*
 193                  * If the password file was replaced while we were trying to
 194                  * get the lock, our hardlink count will be 0 and we have to
 195                  * close and retry.
 196                  */
 197                 if (fstat(lockfd, &st) == -1)
 198                         err(1, "fstat() failed: ");
 199                 if (st.st_nlink != 0)
 200                         break;
 201                 close(lockfd);
 202                 lockfd = -1;
 203         }
 204         return (lockfd);
 205 }
 206
 207 /*
 208  * Create and open a presumably safe temp file for editing the password
 209  * data, and copy the master password file into it.
 210  */
 211 int
 212 pw_tmp(int mfd)
 213 {
 214         char buf[8192];
 215         ssize_t nr;
 216         const char *p;
 217         int tfd;
 218
 219         if (*masterpasswd == '\0')
 220                 return (-1);
 221         if ((p = strrchr(masterpasswd, '/')))
 222                 ++p;
 223         else
 224                 p = masterpasswd;
 225         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 226                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 227                 errno = ENAMETOOLONG;
 228                 return (-1);
 229         }
 230         if ((tfd = mkostemp(tempname, 0)) == -1)
 231                 return (-1);
 232         if (mfd != -1) {
 233                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 234                         if (write(tfd, buf, (size_t)nr) != nr)
 235                                 break;
 236                 if (nr != 0) {
 237                         unlink(tempname);
 238                         *tempname = '\0';
 239                         close(tfd);
 240                         return (-1);
 241                 }
 242         }
 243         return (tfd);
 244 }
 245
 246 /*
 247  * Regenerate the password database.
 248  */
 249 int
 250 pw_mkdb(const char *user)
 251 {
 252         int pstat;
 253         pid_t pid;
 254
 255         (void)fflush(stderr);
 256         switch ((pid = fork())) {
 257         case -1:
 258                 return (-1);
 259         case 0:
 260                 /* child */
 261                 if (user == NULL)
 262                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 263                             "-d", passwd_dir, tempname, (char *)NULL);
 264                 else
 265                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 266                             "-d", passwd_dir, "-u", user, tempname,
 267                             (char *)NULL);
 268                 _exit(1);
 269                 /* NOTREACHED */
 270         default:
 271                 /* parent */
 272                 break;
 273         }
 274         if (waitpid(pid, &pstat, 0) == -1)
 275                 return (-1);
 276         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 277                 return (0);
 278         errno = 0;
 279         return (-1);
 280 }
 281
 282 /*
 283  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 284  * if it was not.
 285  */
 286 int
 287 pw_edit(int notsetuid)
 288 {
 289         struct sigaction sa, sa_int, sa_quit;
 290         sigset_t oldsigset, nsigset;
 291         struct stat st1, st2;
 292         const char *editor;
 293         int pstat;
 294
 295         if ((editor = getenv("EDITOR")) == NULL)
 296                 editor = _PATH_VI;
 297         if (stat(tempname, &st1) == -1)
 298                 return (-1);
 299         sa.sa_handler = SIG_IGN;
 300         sigemptyset(&sa.sa_mask);
 301         sa.sa_flags = 0;
 302         sigaction(SIGINT, &sa, &sa_int);
 303         sigaction(SIGQUIT, &sa, &sa_quit);
 304         sigemptyset(&nsigset);
 305         sigaddset(&nsigset, SIGCHLD);
 306         sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
 307         switch ((editpid = fork())) {
 308         case -1:
 309                 return (-1);
 310         case 0:
 311                 sigaction(SIGINT, &sa_int, NULL);
 312                 sigaction(SIGQUIT, &sa_quit, NULL);
 313                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 314                 if (notsetuid) {
 315                         (void)setgid(getgid());
 316                         (void)setuid(getuid());
 317                 }
 318                 errno = 0;
 319                 execlp(editor, editor, tempname, (char *)NULL);
 320                 _exit(errno);
 321         default:
 322                 /* parent */
 323                 break;
 324         }
 325         for (;;) {
 326                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 327                         if (errno == EINTR)
 328                                 continue;
 329                         unlink(tempname);
 330                         editpid = -1;
 331                         break;
 332                 } else if (WIFSTOPPED(pstat)) {
 333                         raise(WSTOPSIG(pstat));
 334                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 335                         editpid = -1;
 336                         break;
 337                 } else {
 338                         unlink(tempname);
 339                         editpid = -1;
 340                         break;
 341                 }
 342         }
 343         sigaction(SIGINT, &sa_int, NULL);
 344         sigaction(SIGQUIT, &sa_quit, NULL);
 345         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 346         if (stat(tempname, &st2) == -1)
 347                 return (-1);
 348         return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
 349             st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
 350 }
 351
 352 /*
 353  * Clean up.  Preserve errno for the caller's convenience.
 354  */
 355 void
 356 pw_fini(void)
 357 {
 358         int serrno, status;
 359
 360         if (!initialized)
 361                 return;
 362         initialized = 0;
 363         serrno = errno;
 364         if (editpid != -1) {
 365                 kill(editpid, SIGTERM);
 366                 kill(editpid, SIGCONT);
 367                 waitpid(editpid, &status, 0);
 368                 editpid = -1;
 369         }
 370         if (*tempname != '\0') {
 371                 unlink(tempname);
 372                 *tempname = '\0';
 373         }
 374         if (lockfd != -1)
 375                 close(lockfd);
 376         errno = serrno;
 377 }
 378
 379 /*
 380  * Compares two struct pwds.
 381  */
 382 int
 383 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 384 {
 385         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 386             pw1->pw_uid == pw2->pw_uid &&
 387             pw1->pw_gid == pw2->pw_gid &&
 388             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 389             pw1->pw_change == pw2->pw_change &&
 390             pw1->pw_expire == pw2->pw_expire &&
 391             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 392             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 393             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 394 }
 395
 396 /*
 397  * Make a passwd line out of a struct passwd.
 398  */
 399 char *
 400 pw_make(const struct passwd *pw)
 401 {
 402         char *line;
 403
 404         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 405             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 406             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 407             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 408         return (line);
 409 }
 410
 411 /*
 412  * Make a passwd line (in v7 format) out of a struct passwd
 413  */
 414 char *
 415 pw_make_v7(const struct passwd *pw)
 416 {
 417         char *line;
 418
 419         asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
 420             (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 421             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 422         return (line);
 423 }
 424
 425 /*
 426  * Copy password file from one descriptor to another, replacing, deleting
 427  * or adding a single record on the way.
 428  */
 429 int
 430 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 431 {
 432         char *buf, *end, *line, *p, *q, *r, *tmp;
 433         struct passwd *fpw;
 434         const struct passwd *spw;
 435         size_t len, size;
 436         int eof, readlen;
 437         char t;
 438
 439         if (old_pw == NULL && pw == NULL)
 440                         return (-1);
 441
 442         spw = old_pw;
 443         /* deleting a user */
 444         if (pw == NULL) {
 445                 line = NULL;
 446         } else {
 447                 if ((line = pw_make(pw)) == NULL)
 448                         return (-1);
 449         }
 450
 451         /* adding a user */
 452         if (spw == NULL)
 453                 spw = pw;
 454
 455         /* initialize the buffer */
 456         if ((buf = malloc(size = 1024)) == NULL)
 457                 goto err;
 458
 459         eof = 0;
 460         len = 0;
 461         p = q = end = buf;
 462         for (;;) {
 463                 /* find the end of the current line */
 464                 for (p = q; q < end && *q != '\0'; ++q)
 465                         if (*q == '\n')
 466                                 break;
 467
 468                 /* if we don't have a complete line, fill up the buffer */
 469                 if (q >= end) {
 470                         if (eof)
 471                                 break;
 472                         while ((size_t)(q - p) >= size) {
 473                                 if ((tmp = reallocarray(buf, 2, size)) == NULL) {
 474                                         warnx("passwd line too long");
 475                                         goto err;
 476                                 }
 477                                 p = tmp + (p - buf);
 478                                 q = tmp + (q - buf);
 479                                 end = tmp + (end - buf);
 480                                 buf = tmp;
 481                                 size = size * 2;
 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, size - (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 < size) {
 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, size);
 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         free(line);
 584         free(buf);
 585         return (0);
 586  err:
 587         free(line);
 588         free(buf);
 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 }