106 lines
3.4 KiB
C
106 lines
3.4 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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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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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setreuid(effective_uid, real_uid); \
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setregid(effective_gid, real_gid); \
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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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setreuid(effective_uid, real_uid); \
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setregid(effective_gid, real_gid); \
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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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