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112 lines
3.9 KiB
C
112 lines
3.9 KiB
C
/*
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* privs.h - header for privileged operations
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* Copyright (C) 1993 Thomas Koenig
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. The name of the author(s) may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _PRIVS_H
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#define _PRIVS_H
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#ifndef _USE_BSD
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#define _USE_BSD 1
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#include <unistd.h>
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#undef _USE_BSD
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#else
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#include <unistd.h>
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#endif
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/* Relinquish privileges temporarily for a setuid or setgid program
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* with the option of getting them back later. This is done by swapping
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* the real and effective userid BSD style. Call RELINQUISH_PRIVS once
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* at the beginning of the main program. This will cause all operatons
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* to be executed with the real userid. When you need the privileges
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* of the setuid/setgid invocation, call PRIV_START; when you no longer
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* need it, call PRIV_END. Note that it is an error to call PRIV_START
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* and not PRIV_END within the same function.
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*
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* Use RELINQUISH_PRIVS_ROOT(a,b) if your program started out running
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* as root, and you want to drop back the effective userid to a
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* and the effective group id to b, with the option to get them back
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* later.
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*
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* If you no longer need root privileges, but those of some other
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* userid/groupid, you can call REDUCE_PRIV(a,b) when your effective
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* is the user's.
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*
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* Problems: Do not use return between PRIV_START and PRIV_END; this
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* will cause the program to continue running in an unprivileged
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* state.
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*
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* It is NOT safe to call exec(), system() or popen() with a user-
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* supplied program (i.e. without carefully checking PATH and any
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* library load paths) with relinquished privileges; the called program
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* can aquire them just as easily. Set both effective and real userid
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* to the real userid before calling any of them.
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*/
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#ifndef MAIN
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extern
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#endif
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uid_t real_uid, effective_uid;
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#ifndef MAIN
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extern
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#endif
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gid_t real_gid, effective_gid;
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#define RELINQUISH_PRIVS { \
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real_uid = getuid(); \
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effective_uid = geteuid(); \
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real_gid = getgid(); \
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effective_gid = getegid(); \
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setreuid(effective_uid, real_uid); \
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setregid(effective_gid, real_gid); \
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}
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#define RELINQUISH_PRIVS_ROOT(a,b) { \
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real_uid = (a); \
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effective_uid = geteuid(); \
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real_gid = (b); \
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effective_gid = getegid(); \
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setregid(effective_gid, real_gid); \
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setreuid(effective_uid, real_uid); \
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}
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#define PRIV_START {\
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setreuid(real_uid, effective_uid); \
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setregid(real_gid, effective_gid);
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#define PRIV_END \
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setregid(effective_gid, real_gid); \
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setreuid(effective_uid, real_uid); \
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}
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#define REDUCE_PRIV(a,b) {\
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setreuid(real_uid, effective_uid); \
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setregid(real_gid, effective_gid); \
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effective_uid = (a); \
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effective_gid = (b); \
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setregid(effective_gid, real_gid); \
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setreuid(effective_uid, real_uid); \
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}
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#endif
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