1 .\" Copyright (C) 1997 Andries Brouwer (aeb@cwi.nl)
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25 .\" Modified, 2003-05-26, Michael Kerrisk, <mtk.manpages@gmail.com>
26 .TH SETRESUID 2 2014-09-21 "Linux" "Linux Programmer's Manual"
28 setresuid, setresgid \- set real, effective and saved user or group ID
30 .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
32 .B #include <unistd.h>
34 .BI "int setresuid(uid_t " ruid ", uid_t " euid ", uid_t " suid );
36 .BI "int setresgid(gid_t " rgid ", gid_t " egid ", gid_t " sgid );
39 sets the real user ID, the effective user ID, and the
40 saved set-user-ID of the calling process.
42 Unprivileged user processes
43 may change the real UID,
44 effective UID, and saved set-user-ID, each to one of:
45 the current real UID, the current effective UID or the
46 current saved set-user-ID.
48 Privileged processes (on Linux, those having the \fBCAP_SETUID\fP capability)
49 may set the real UID, effective UID, and
50 saved set-user-ID to arbitrary values.
52 If one of the arguments equals \-1, the corresponding value is not changed.
54 Regardless of what changes are made to the real UID, effective UID,
55 and saved set-user-ID, the filesystem UID is always set to the same
56 value as the (possibly new) effective UID.
58 Completely analogously,
60 sets the real GID, effective GID, and saved set-group-ID
61 of the calling process (and always modifies the filesystem GID
62 to be the same as the effective GID),
63 with the same restrictions for unprivileged processes.
65 On success, zero is returned.
66 On error, \-1 is returned, and
73 can fail even when the caller is UID 0;
74 it is a grave security error to omit checking for a failure return from
79 The call would change the caller's real UID (i.e.,
81 does not match the caller's real UID),
82 but there was a temporary failure allocating the
83 necessary kernel data structures.
87 does not match the caller's real UID and this call would
88 bring the number of processes belonging to the real user ID
93 Since Linux 3.1, this error case no longer occurs
94 (but robust applications should check for this error);
95 see the description of
101 One or more of the target user or group IDs
102 is not valid in this user namespace.
105 The calling process is not privileged (did not have the \fBCAP_SETUID\fP
106 capability) and tried to change the IDs to values that are not permitted.
108 These calls are available under Linux since Linux 2.1.44.
110 These calls are nonstandard;
111 they also appear on HP-UX and some of the BSDs.
113 Under HP-UX and FreeBSD, the prototype is found in
115 Under Linux, the prototype is provided by glibc since version 2.3.2.
121 system calls supported only 16-bit user and group IDs.
122 Subsequently, Linux 2.4 added
126 supporting 32-bit IDs.
131 wrapper functions transparently deal with the variations across kernel versions.
139 .BR capabilities (7),
141 .BR user_namespaces (7)
143 This page is part of release 3.79 of the Linux
146 A description of the project,
147 information about reporting bugs,
148 and the latest version of this page,
150 \%http://www.kernel.org/doc/man\-pages/.