usr.bin/at/privs.h

   1 /*      $NetBSD: privs.h,v 1.7 2003/10/21 09:03:25 wiz Exp $    */
   2
   3 /*
   4  *  privs.h - header for privileged operations
   5  *  Copyright (C) 1993  Thomas Koenig
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. The name of the author(s) may not be used to endorse or promote
  13  *    products derived from this software without specific prior written
  14  *    permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  *
  27  * From: OpenBSD: privs.h,v 1.4 1997/03/01 23:40:12 millert Exp
  28  */
  29
  30 #ifndef _PRIVS_H_
  31 #define _PRIVS_H_
  32
  33 #include <unistd.h>
  34
  35 /* Relinquish privileges temporarily for a setuid or setgid program
  36  * with the option of getting them back later.  This is done by
  37  * using POSIX saved user and groups ids.  Call RELINQUISH_PRIVS once
  38  * at the beginning of the main program.  This will cause all operations
  39  * to be executed with the real userid.  When you need the privileges
  40  * of the setuid/setgid invocation, call PRIV_START; when you no longer
  41  * need it, call PRIV_END.  Note that it is an error to call PRIV_START
  42  * and not PRIV_END within the same function.
  43  *
  44  * Use RELINQUISH_PRIVS_ROOT(a,b) if your program started out running
  45  * as root, and you want to drop back the effective userid to a
  46  * and the effective group id to b, with the option to get them back
  47  * later.
  48  *
  49  * Problems: Do not use return between PRIV_START and PRIV_END; this
  50  * will cause the program to continue running in an unprivileged
  51  * state.
  52  *
  53  * It is NOT safe to call exec(), system() or popen() with a user-
  54  * supplied program (i.e. without carefully checking PATH and any
  55  * library load paths) with relinquished privileges; the called program
  56  * can acquire them just as easily.  Set both effective and real userid
  57  * to the real userid before calling any of them.
  58  */
  59
  60 #ifndef MAIN
  61 extern
  62 #endif
  63 uid_t real_uid, effective_uid;
  64
  65 #ifndef MAIN
  66 extern
  67 #endif
  68 gid_t real_gid, effective_gid;
  69
  70 #define RELINQUISH_PRIVS do { \
  71       real_uid = getuid(); \
  72       effective_uid = geteuid(); \
  73       real_gid = getgid(); \
  74       effective_gid = getegid(); \
  75       PRIV_END; \
  76 } while (/*CONSTCOND*/ 0)
  77
  78 #define RELINQUISH_PRIVS_ROOT(a, b) do { \
  79         real_uid = (a); \
  80         effective_uid = geteuid(); \
  81         real_gid = (b); \
  82         effective_gid = getegid(); \
  83         PRIV_END; \
  84 } while (/*CONSTCOND*/ 0)
  85
  86 #define PRIV_START do { \
  87         if (seteuid(effective_uid) == -1) \
  88                 perr("Cannot get user privs"); \
  89         if (setegid(effective_gid) == -1) \
  90                 perr("Cannot get group privs"); \
  91 } while (/*CONSTCOND*/ 0)
  92
  93 #define PRIV_END do { \
  94         if (setegid(real_gid) == -1) \
  95                 perr("Cannot relinguish group privs"); \
  96         if (seteuid(real_uid) == -1) \
  97                 perr("Cannot relinguish user privs"); \
  98 } while (/*CONSTCOND*/ 0)
  99
 100 #endif /* _PRIV_H_ */