1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 1997-2001 by Sun Microsystems, Inc.
  24  * All rights reserved.
  25  */
  26 
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T     */
  28 /*        All Rights Reserved   */
  29 
  30 
  31 #pragma ident   "%Z%%M% %I%     %E% SMI"        /* SVr4.0 1.5 */
  32 
  33 #include <sys/types.h>
  34 #include <stdio.h>
  35 #include <userdefs.h>
  36 #include <pwd.h>
  37 
  38 #include <sys/param.h>
  39 #ifndef MAXUID
  40 #include <limits.h>
  41 #ifdef UID_MAX
  42 #define MAXUID  UID_MAX
  43 #else
  44 #define MAXUID  60000
  45 #endif
  46 #endif
  47 
  48 static uid_t getrangeboundid(uid_t start, uid_t stop);
  49 static int isreserveduid(uid_t uid);
  50 
  51 /*
  52  * Find the highest uid currently in use and return it. If the highest unused
  53  * uid is MAXUID, then attempt to find a hole in the range. If there are no
  54  * more unused uids, then return -1.
  55  */
  56 uid_t
  57 findnextuid(void)
  58 {
  59         uid_t uid = DEFRID + 1;
  60         struct passwd *pwd;
  61         uchar_t overflow = 0;
  62 
  63         setpwent();
  64         for (pwd = getpwent(); pwd != NULL; pwd = getpwent()) {
  65                 if (isreserveduid(pwd->pw_uid))              /* Skip reserved IDs */
  66                         continue;
  67                 if (pwd->pw_uid >= uid) {
  68                         if (pwd->pw_uid == MAXUID) { /* Overflow check */
  69                                 overflow = 1;
  70                                 break;
  71                         }
  72                         uid = pwd->pw_uid + 1;
  73                         while (isreserveduid(uid) &&
  74                             uid < MAXUID) {          /* Skip reserved IDs */
  75                                 uid++;
  76                         }
  77                 }
  78         }
  79         endpwent();
  80         if (overflow == 1)                              /* Find a hole */
  81                 return (getrangeboundid(DEFRID + 1, MAXUID));
  82         return (uid);
  83 }
  84 
  85 /*
  86  * Check to see that the uid is a reserved uid
  87  * -- nobody, noaccess or nobody4
  88  */
  89 static int
  90 isreserveduid(uid_t uid)
  91 {
  92         return (uid == 60001 || uid == 60002 || uid == 65534);
  93 }
  94 
  95 
  96 /*
  97  * getrangeboundid() attempts to return the next valid usable id between the
  98  * supplied upper and lower limits. If these limits exceed the system
  99  * boundaries of DEFRID +1 and MAXUID (lower and upper bound respectively),
 100  * then they are ignored and DEFRID + 1 and MAXUID are used.
 101  *
 102  * Returns a valid uid_t between DEFRID +1 and MAXUID, -1 is returned on fail
 103  */
 104 static uid_t
 105 getrangeboundid(uid_t start, uid_t stop)
 106 {
 107         uid_t low = (start <= DEFRID) ? DEFRID + 1 : start;
 108         uid_t high = (stop < MAXUID) ? stop : MAXUID;
 109         uid_t uid;
 110 
 111         for (uid = low; uid <= high; uid++) {
 112                 if (isreserveduid(uid))
 113                         continue;
 114                 if (getpwuid(uid) == NULL)
 115                         break;
 116         }
 117         return ((uid > high) ? -1 : uid);
 118 }