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