2 * privs.h - header for privileged operations
3 * Copyright (C) 1993 Thomas Koenig
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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9 * notice, this list of conditions and the following disclaimer.
10 * 2. The name of the author(s) may not be used to endorse or promote
11 * products derived from this software without specific prior written
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
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16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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25 * $FreeBSD: src/usr.bin/at/privs.h,v 1.7 1999/12/05 19:57:14 charnier Exp $
26 * $DragonFly: src/usr.bin/at/privs.h,v 1.2 2003/06/17 04:29:25 dillon Exp $
40 /* Relinquish privileges temporarily for a setuid or setgid program
41 * with the option of getting them back later. This is done by swapping
42 * the real and effective userid BSD style. Call RELINQUISH_PRIVS once
43 * at the beginning of the main program. This will cause all operations
44 * to be executed with the real userid. When you need the privileges
45 * of the setuid/setgid invocation, call PRIV_START; when you no longer
46 * need it, call PRIV_END. Note that it is an error to call PRIV_START
47 * and not PRIV_END within the same function.
49 * Use RELINQUISH_PRIVS_ROOT(a,b) if your program started out running
50 * as root, and you want to drop back the effective userid to a
51 * and the effective group id to b, with the option to get them back
54 * If you no longer need root privileges, but those of some other
55 * userid/groupid, you can call REDUCE_PRIV(a,b) when your effective
58 * Problems: Do not use return between PRIV_START and PRIV_END; this
59 * will cause the program to continue running in an unprivileged
62 * It is NOT safe to call exec(), system() or popen() with a user-
63 * supplied program (i.e. without carefully checking PATH and any
64 * library load paths) with relinquished privileges; the called program
65 * can acquire them just as easily. Set both effective and real userid
66 * to the real userid before calling any of them.
72 uid_t real_uid, effective_uid;
77 gid_t real_gid, effective_gid;
79 #define RELINQUISH_PRIVS { \
80 real_uid = getuid(); \
81 effective_uid = geteuid(); \
82 real_gid = getgid(); \
83 effective_gid = getegid(); \
84 setreuid(effective_uid, real_uid); \
85 setregid(effective_gid, real_gid); \
88 #define RELINQUISH_PRIVS_ROOT(a,b) { \
90 effective_uid = geteuid(); \
92 effective_gid = getegid(); \
93 setregid(effective_gid, real_gid); \
94 setreuid(effective_uid, real_uid); \
98 setreuid(real_uid, effective_uid); \
99 setregid(real_gid, effective_gid);
102 setregid(effective_gid, real_gid); \
103 setreuid(effective_uid, real_uid); \
106 #define REDUCE_PRIV(a,b) {\
107 setreuid(real_uid, effective_uid); \
108 setregid(real_gid, effective_gid); \
109 effective_uid = (a); \
110 effective_gid = (b); \
111 setregid(effective_gid, real_gid); \
112 setreuid(effective_uid, real_uid); \