lib/libutil/pw_util.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 2002 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * Portions of this software were developed for the FreeBSD Project by
   8  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   9  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  10  * ("CBOSS"), as part of the DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)pw_util.c        8.3 (Berkeley) 4/2/94
  37  * $FreeBSD: src/lib/libutil/pw_util.c,v 1.38 2007/01/09 01:02:05 imp Exp $
  38  * $DragonFly: src/lib/libutil/pw_util.c,v 1.2 2007/12/30 13:44:33 matthias Exp $
  39  */
  40
  41 /*
  42  * This file is used by all the "password" programs; vipw(8), chpass(1),
  43  * and passwd(1).
  44  */
  45
  46 #include <sys/param.h>
  47 #include <sys/errno.h>
  48 #include <sys/time.h>
  49 #include <sys/resource.h>
  50 #include <sys/stat.h>
  51 #include <sys/wait.h>
  52
  53 #include <ctype.h>
  54 #include <err.h>
  55 #include <fcntl.h>
  56 #include <inttypes.h>
  57 #include <libgen.h>
  58 #include <paths.h>
  59 #include <pwd.h>
  60 #include <signal.h>
  61 #include <stdio.h>
  62 #include <stdlib.h>
  63 #include <string.h>
  64 #include <unistd.h>
  65
  66 #include <libutil.h>
  67
  68 static pid_t editpid = -1;
  69 static int lockfd = -1;
  70 static char masterpasswd[PATH_MAX];
  71 static char passwd_dir[PATH_MAX];
  72 static char tempname[PATH_MAX];
  73 static int initialized;
  74
  75 #if 0
  76 void
  77 pw_cont(int sig)
  78 {
  79
  80         if (editpid != -1)
  81                 kill(editpid, sig);
  82 }
  83 #endif
  84
  85 /*
  86  * Initialize statics and set limits, signals & umask to try to avoid
  87  * interruptions, crashes etc. that might expose passord data.
  88  */
  89 int
  90 pw_init(const char *dir, const char *master)
  91 {
  92 #if 0
  93         struct rlimit rlim;
  94 #endif
  95
  96         if (dir == NULL) {
  97                 strcpy(passwd_dir, _PATH_ETC);
  98         } else {
  99                 if (strlen(dir) >= sizeof(passwd_dir)) {
 100                         errno = ENAMETOOLONG;
 101                         return (-1);
 102                 }
 103                 strcpy(passwd_dir, dir);
 104         }
 105
 106         if (master == NULL) {
 107                 if (dir == NULL) {
 108                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 109                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 110                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 111                         errno = ENAMETOOLONG;
 112                         return (-1);
 113                 }
 114         } else {
 115                 if (strlen(master) >= sizeof(masterpasswd)) {
 116                         errno = ENAMETOOLONG;
 117                         return (-1);
 118                 }
 119                 strcpy(masterpasswd, master);
 120         }
 121
 122         /*
 123          * The code that follows is extremely disruptive to the calling
 124          * process, and is therefore disabled until someone can conceive
 125          * of a realistic scenario where it would fend off a compromise.
 126          * Race conditions concerning the temporary files can be guarded
 127          * against in other ways than masking signals (by checking stat(2)
 128          * results after creation).
 129          */
 130 #if 0
 131         /* Unlimited resource limits. */
 132         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 133         (void)setrlimit(RLIMIT_CPU, &rlim);
 134         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 135         (void)setrlimit(RLIMIT_STACK, &rlim);
 136         (void)setrlimit(RLIMIT_DATA, &rlim);
 137         (void)setrlimit(RLIMIT_RSS, &rlim);
 138
 139         /* Don't drop core (not really necessary, but GP's). */
 140         rlim.rlim_cur = rlim.rlim_max = 0;
 141         (void)setrlimit(RLIMIT_CORE, &rlim);
 142
 143         /* Turn off signals. */
 144         (void)signal(SIGALRM, SIG_IGN);
 145         (void)signal(SIGHUP, SIG_IGN);
 146         (void)signal(SIGINT, SIG_IGN);
 147         (void)signal(SIGPIPE, SIG_IGN);
 148         (void)signal(SIGQUIT, SIG_IGN);
 149         (void)signal(SIGTERM, SIG_IGN);
 150         (void)signal(SIGCONT, pw_cont);
 151
 152         /* Create with exact permissions. */
 153         (void)umask(0);
 154 #endif
 155         initialized = 1;
 156         return (0);
 157 }
 158
 159 /*
 160  * Lock the master password file.
 161  */
 162 int
 163 pw_lock(void)
 164 {
 165
 166         if (*masterpasswd == '\0')
 167                 return (-1);
 168
 169         /*
 170          * If the master password file doesn't exist, the system is hosed.
 171          * Might as well try to build one.  Set the close-on-exec bit so
 172          * that users can't get at the encrypted passwords while editing.
 173          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 174          */
 175         for (;;) {
 176                 struct stat st;
 177
 178                 lockfd = open(masterpasswd, O_RDONLY, 0);
 179                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 180                         err(1, "%s", masterpasswd);
 181                 /* XXX vulnerable to race conditions */
 182                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 183                         if (errno == EWOULDBLOCK) {
 184                                 errx(1, "the password db file is busy");
 185                         } else {
 186                                 err(1, "could not lock the passwd file: ");
 187                         }
 188                 }
 189
 190                 /*
 191                  * If the password file was replaced while we were trying to
 192                  * get the lock, our hardlink count will be 0 and we have to
 193                  * close and retry.
 194                  */
 195                 if (fstat(lockfd, &st) == -1)
 196                         err(1, "fstat() failed: ");
 197                 if (st.st_nlink != 0)
 198                         break;
 199                 close(lockfd);
 200                 lockfd = -1;
 201         }
 202         return (lockfd);
 203 }
 204
 205 /*
 206  * Create and open a presumably safe temp file for editing the password
 207  * data, and copy the master password file into it.
 208  */
 209 int
 210 pw_tmp(int mfd)
 211 {
 212         char buf[8192];
 213         ssize_t nr;
 214         const char *p;
 215         int tfd;
 216
 217         if (*masterpasswd == '\0')
 218                 return (-1);
 219         if ((p = strrchr(masterpasswd, '/')))
 220                 ++p;
 221         else
 222                 p = masterpasswd;
 223         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 224                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 225                 errno = ENAMETOOLONG;
 226                 return (-1);
 227         }
 228         if ((tfd = mkstemp(tempname)) == -1)
 229                 return (-1);
 230         if (mfd != -1) {
 231                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 232                         if (write(tfd, buf, (size_t)nr) != nr)
 233                                 break;
 234                 if (nr != 0) {
 235                         unlink(tempname);
 236                         *tempname = '\0';
 237                         close(tfd);
 238                         return (-1);
 239                 }
 240         }
 241         return (tfd);
 242 }
 243
 244 /*
 245  * Regenerate the password database.
 246  */
 247 int
 248 pw_mkdb(const char *user)
 249 {
 250         int pstat;
 251         pid_t pid;
 252
 253         (void)fflush(stderr);
 254         switch ((pid = fork())) {
 255         case -1:
 256                 return (-1);
 257         case 0:
 258                 /* child */
 259                 if (user == NULL)
 260                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 261                             "-d", passwd_dir, tempname, NULL);
 262                 else
 263                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 264                             "-d", passwd_dir, "-u", user, tempname,
 265                             NULL);
 266                 _exit(1);
 267                 /* NOTREACHED */
 268         default:
 269                 /* parent */
 270                 break;
 271         }
 272         if (waitpid(pid, &pstat, 0) == -1)
 273                 return (-1);
 274         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 275                 return (0);
 276         errno = 0;
 277         return (-1);
 278 }
 279
 280 /*
 281  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 282  * if it was not.
 283  */
 284 int
 285 pw_edit(int notsetuid)
 286 {
 287         struct sigaction sa, sa_int, sa_quit;
 288         sigset_t oldsigset, sigset;
 289         struct stat st1, st2;
 290         const char *editor;
 291         int pstat;
 292
 293         if ((editor = getenv("EDITOR")) == NULL)
 294                 editor = _PATH_VI;
 295         if (stat(tempname, &st1) == -1)
 296                 return (-1);
 297         sa.sa_handler = SIG_IGN;
 298         sigemptyset(&sa.sa_mask);
 299         sa.sa_flags = 0;
 300         sigaction(SIGINT, &sa, &sa_int);
 301         sigaction(SIGQUIT, &sa, &sa_quit);
 302         sigemptyset(&sigset);
 303         sigaddset(&sigset, SIGCHLD);
 304         sigprocmask(SIG_BLOCK, &sigset, &oldsigset);
 305         switch ((editpid = fork())) {
 306         case -1:
 307                 return (-1);
 308         case 0:
 309                 sigaction(SIGINT, &sa_int, NULL);
 310                 sigaction(SIGQUIT, &sa_quit, NULL);
 311                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 312                 if (notsetuid) {
 313                         setgid(getgid());
 314                         setuid(getuid());
 315                 }
 316                 errno = 0;
 317                 execlp(editor, basename(editor), tempname, NULL);
 318                 _exit(errno);
 319         default:
 320                 /* parent */
 321                 break;
 322         }
 323         for (;;) {
 324                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 325                         if (errno == EINTR)
 326                                 continue;
 327                         unlink(tempname);
 328                         editpid = -1;
 329                         break;
 330                 } else if (WIFSTOPPED(pstat)) {
 331                         raise(WSTOPSIG(pstat));
 332                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 333                         editpid = -1;
 334                         break;
 335                 } else {
 336                         unlink(tempname);
 337                         editpid = -1;
 338                         break;
 339                 }
 340         }
 341         sigaction(SIGINT, &sa_int, NULL);
 342         sigaction(SIGQUIT, &sa_quit, NULL);
 343         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 344         if (stat(tempname, &st2) == -1)
 345                 return (-1);
 346         return (st1.st_mtime != st2.st_mtime);
 347 }
 348
 349 /*
 350  * Clean up.  Preserve errno for the caller's convenience.
 351  */
 352 void
 353 pw_fini(void)
 354 {
 355         int serrno, status;
 356
 357         if (!initialized)
 358                 return;
 359         initialized = 0;
 360         serrno = errno;
 361         if (editpid != -1) {
 362                 kill(editpid, SIGTERM);
 363                 kill(editpid, SIGCONT);
 364                 waitpid(editpid, &status, 0);
 365                 editpid = -1;
 366         }
 367         if (*tempname != '\0') {
 368                 unlink(tempname);
 369                 *tempname = '\0';
 370         }
 371         if (lockfd != -1)
 372                 close(lockfd);
 373         errno = serrno;
 374 }
 375
 376 /*
 377  * Compares two struct pwds.
 378  */
 379 int
 380 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 381 {
 382         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 383             pw1->pw_uid == pw2->pw_uid &&
 384             pw1->pw_gid == pw2->pw_gid &&
 385             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 386             pw1->pw_change == pw2->pw_change &&
 387             pw1->pw_expire == pw2->pw_expire &&
 388             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 389             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 390             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 391 }
 392
 393 /*
 394  * Make a passwd line out of a struct passwd.
 395  */
 396 char *
 397 pw_make(const struct passwd *pw)
 398 {
 399         char *line;
 400
 401         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 402             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 403             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 404             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 405         return line;
 406 }
 407
 408 /*
 409  * Copy password file from one descriptor to another, replacing or adding
 410  * a single record on the way.
 411  */
 412 int
 413 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 414 {
 415         char buf[8192], *end, *line, *p, *q, *r, t;
 416         struct passwd *fpw;
 417         size_t len;
 418         int eof, readlen;
 419
 420         if ((line = pw_make(pw)) == NULL)
 421                 return (-1);
 422
 423         eof = 0;
 424         q = end = buf;
 425         for (;;) {
 426                 /* find the end of the current line */
 427                 for (p = q; q < end && *q != '\0'; ++q)
 428                         if (*q == '\n')
 429                                 break;
 430
 431                 /* if we don't have a complete line, fill up the buffer */
 432                 if (q >= end) {
 433                         if (eof)
 434                                 break;
 435                         if ((size_t)(q - p) >= sizeof(buf)) {
 436                                 warnx("passwd line too long");
 437                                 errno = EINVAL; /* hack */
 438                                 goto err;
 439                         }
 440                         if (p < end) {
 441                                 q = memmove(buf, p, end - p);
 442                                 end -= p - buf;
 443                         } else {
 444                                 p = q = end = buf;
 445                         }
 446                         readlen = read(ffd, end, sizeof(buf) - (end - buf));
 447                         if (readlen == -1)
 448                                 goto err;
 449                         else
 450                                 len = (size_t)readlen;
 451                         if (len == 0 && p == buf)
 452                                 break;
 453                         end += len;
 454                         len = end - buf;
 455                         if (len < (ssize_t)sizeof(buf)) {
 456                                 eof = 1;
 457                                 if (len > 0 && buf[len - 1] != '\n')
 458                                         *end++ = '\n';
 459                         }
 460                         continue;
 461                 }
 462
 463                 /* is it a blank line or a comment? */
 464                 for (r = p; r < q && isspace(*r); ++r)
 465                         /* nothing */ ;
 466                 if (r == q || *r == '#') {
 467                         /* yep */
 468                         if (write(tfd, p, q - p + 1) != q - p + 1)
 469                                 goto err;
 470                         ++q;
 471                         continue;
 472                 }
 473
 474                 /* is it the one we're looking for? */
 475
 476                 t = *q;
 477                 *q = '\0';
 478
 479                 fpw = pw_scan(r, PWSCAN_MASTER);
 480
 481                 /*
 482                  * fpw is either the struct passwd for the current line,
 483                  * or NULL if the line is malformed.
 484                  */
 485
 486                 *q = t;
 487                 if (fpw == NULL || strcmp(fpw->pw_name, pw->pw_name) != 0) {
 488                         /* nope */
 489                         if (fpw != NULL)
 490                                 free(fpw);
 491                         if (write(tfd, p, q - p + 1) != q - p + 1)
 492                                 goto err;
 493                         ++q;
 494                         continue;
 495                 }
 496                 if (old_pw && !pw_equal(fpw, old_pw)) {
 497                         warnx("entry inconsistent");
 498                         free(fpw);
 499                         errno = EINVAL; /* hack */
 500                         goto err;
 501                 }
 502                 free(fpw);
 503
 504                 /* it is, replace it */
 505                 len = strlen(line);
 506                 if (write(tfd, line, len) != (int)len)
 507                         goto err;
 508
 509                 /* we're done, just copy the rest over */
 510                 for (;;) {
 511                         if (write(tfd, q, end - q) != end - q)
 512                                 goto err;
 513                         q = buf;
 514                         readlen = read(ffd, buf, sizeof(buf));
 515                         if (readlen == 0)
 516                                 break;
 517                         else
 518                                 len = (size_t)readlen;
 519                         if (readlen == -1)
 520                                 goto err;
 521                         end = buf + len;
 522                 }
 523                 goto done;
 524         }
 525
 526         /* if we got here, we have a new entry */
 527         len = strlen(line);
 528         if ((size_t)write(tfd, line, len) != len ||
 529             write(tfd, "\n", 1) != 1)
 530                 goto err;
 531  done:
 532         free(line);
 533         return (0);
 534  err:
 535         free(line);
 536         return (-1);
 537 }
 538
 539 /*
 540  * Return the current value of tempname.
 541  */
 542 const char *
 543 pw_tempname(void)
 544 {
 545
 546         return (tempname);
 547 }
 548
 549 /*
 550  * Duplicate a struct passwd.
 551  */
 552 struct passwd *
 553 pw_dup(const struct passwd *pw)
 554 {
 555         struct passwd *npw;
 556         ssize_t len;
 557
 558         len = sizeof(*npw) +
 559             (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) +
 560             (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) +
 561             (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) +
 562             (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) +
 563             (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) +
 564             (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0);
 565         if ((npw = malloc((size_t)len)) == NULL)
 566                 return (NULL);
 567         memcpy(npw, pw, sizeof(*npw));
 568         len = sizeof(*npw);
 569         if (pw->pw_name) {
 570                 npw->pw_name = ((char *)npw) + len;
 571                 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1;
 572         }
 573         if (pw->pw_passwd) {
 574                 npw->pw_passwd = ((char *)npw) + len;
 575                 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1;
 576         }
 577         if (pw->pw_class) {
 578                 npw->pw_class = ((char *)npw) + len;
 579                 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1;
 580         }
 581         if (pw->pw_gecos) {
 582                 npw->pw_gecos = ((char *)npw) + len;
 583                 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1;
 584         }
 585         if (pw->pw_dir) {
 586                 npw->pw_dir = ((char *)npw) + len;
 587                 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1;
 588         }
 589         if (pw->pw_shell) {
 590                 npw->pw_shell = ((char *)npw) + len;
 591                 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1;
 592         }
 593         return (npw);
 594 }
 595
 596 #include "pw_scan.h"
 597
 598 /*
 599  * Wrapper around an internal libc function
 600  */
 601 struct passwd *
 602 pw_scan(const char *line, int flags)
 603 {
 604         struct passwd pw, *ret;
 605         char *bp;
 606
 607         if ((bp = strdup(line)) == NULL)
 608                 return (NULL);
 609         if (!__pw_scan(bp, &pw, flags)) {
 610                 free(bp);
 611                 return (NULL);
 612         }
 613         ret = pw_dup(&pw);
 614         free(bp);
 615         return (ret);
 616 }