usr/src/lib/libcmdutils/common/uid.c

   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  * Copyright (c) 2013 RackTop Systems.
  32  */
  33
  34 #include <errno.h>
  35 #include <sys/types.h>
  36 #include <stdio.h>
  37 #include <userdefs.h>
  38 #include <pwd.h>
  39 #include <libcmdutils.h>
  40
  41 static int findunuseduid(uid_t start, uid_t stop, uid_t *ret);
  42 static boolean_t isreserveduid(uid_t uid);
  43
  44 /*
  45  * Find the highest unused uid. If the highest unused uid is "stop",
  46  * then attempt to find a hole in the range. Returns 0 on success.
  47  */
  48 int
  49 findnextuid(uid_t start, uid_t stop, uid_t *ret)
  50 {
  51         uid_t uid = start;
  52         struct passwd *pwd;
  53         boolean_t overflow = B_FALSE;
  54
  55         setpwent();
  56         for (pwd = getpwent(); pwd != NULL; pwd = getpwent()) {
  57                 if (isreserveduid(pwd->pw_uid))         /* Skip reserved IDs */
  58                         continue;
  59                 if (pwd->pw_uid >= uid) {
  60                         if (pwd->pw_uid == stop) {      /* Overflow check */
  61                                 overflow = B_TRUE;
  62                                 break;
  63                         }
  64                         uid = pwd->pw_uid + 1;
  65                 }
  66         }
  67         if (pwd == NULL && errno != 0) {
  68                 endpwent();
  69                 return (-1);
  70         }
  71         endpwent();
  72         if (overflow == B_TRUE)                         /* Find a hole */
  73                 return (findunuseduid(start, stop, ret));
  74         while (isreserveduid(uid) && uid < stop)        /* Skip reserved IDs */
  75                 uid++;
  76         *ret = uid;
  77         return (0);
  78 }
  79
  80 /*
  81  * Check to see whether the uid is a reserved uid
  82  * -- nobody, noaccess or nobody4
  83  */
  84 static boolean_t
  85 isreserveduid(uid_t uid)
  86 {
  87         return (uid == 60001 || uid == 60002 || uid == 65534);
  88 }
  89
  90 /*
  91  * findunuseduid() attempts to return the next valid usable id between the
  92  * supplied upper and lower limits. Returns 0 on success.
  93  */
  94 static int
  95 findunuseduid(uid_t start, uid_t stop, uid_t *ret)
  96 {
  97         uid_t uid;
  98
  99         for (uid = start; uid <= stop; uid++) {
 100                 if (isreserveduid(uid))
 101                         continue;
 102                 if (getpwuid(uid) == NULL) {
 103                         if (errno != 0)
 104                                 return (-1);
 105                         break;
 106                 }
 107         }
 108         if (uid > stop)
 109                 return (-1);
 110         *ret = uid;
 111         return (0);
 112 }