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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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SETREGID(3P) POSIX Programmer's Manual SETREGID(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
setregid — set real and effective group IDs
#include <unistd.h>
int setregid(gid_t rgid, gid_t egid);
The setregid() function shall set the real and effective group IDs
of the calling process.
If rgid is -1, the real group ID shall not be changed; if egid is
-1, the effective group ID shall not be changed.
The real and effective group IDs may be set to different values in
the same call.
Only a process with appropriate privileges can set the real group
ID and the effective group ID to any valid value.
A non-privileged process can set either the real group ID to the
saved set-group-ID from one of the exec family of functions, or
the effective group ID to the saved set-group-ID or the real group
ID.
If the real group ID is being set (rgid is not -1), or the
effective group ID is being set to a value not equal to the real
group ID, then the saved set-group-ID of the current process shall
be set equal to the new effective group ID.
Any supplementary group IDs of the calling process remain
unchanged.
Upon successful completion, 0 shall be returned. Otherwise, -1
shall be returned and errno set to indicate the error, and neither
of the group IDs are changed.
The setregid() function shall fail if:
EINVAL The value of the rgid or egid argument is invalid or out-
of-range.
EPERM The process does not have appropriate privileges and a
change other than changing the real group ID to the saved
set-group-ID, or changing the effective group ID to the
real group ID or the saved set-group-ID, was requested.
The following sections are informative.
None.
If a non-privileged set-group-ID process sets its effective group
ID to its real group ID, it can only set its effective group ID
back to the previous value if rgid was -1 in the setregid() call,
since the saved-group-ID is not changed in that case. If rgid was
equal to the real group ID in the setregid() call, then the saved
set-group-ID will also have been changed to the real user ID.
Earlier versions of this standard did not specify whether the
saved set-group-ID was affected by setregid() calls. This version
specifies common existing practice that constitutes an important
security feature. The ability to set both the effective group ID
and saved set-group-ID to be the same as the real group ID means
that any security weakness in code that is executed after that
point cannot result in malicious code being executed with the
previous effective group ID. Privileged applications could already
do this using just setgid(), but for non-privileged applications
the only standard method available is to use this feature of
setregid().
None.
exec(1p), getegid(3p), geteuid(3p), getgid(3p), getuid(3p),
setegid(3p), seteuid(3p), setgid(3p), setreuid(3p), setuid(3p)
The Base Definitions volume of POSIX.1‐2017, unistd.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 SETREGID(3P)
Pages that refer to this page: unistd.h(0p), getegid(3p), geteuid(3p), getgid(3p), getuid(3p), setegid(3p), seteuid(3p), setgid(3p), setreuid(3p), setuid(3p)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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