Section (2) seteuid
Name
seteuid, setegid — set effective user or group ID
Synopsis
#include <sys/types.h> #include <unistd.h>
int
seteuid( |
uid_t euid); |
int
setegid( |
gid_t egid); |
![[Note]](../stylesheet/note.png) |
Note | |||
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DESCRIPTION
seteuid() sets the effective
user ID of the calling process. Unprivileged processes may
only set the effective user ID to the real user ID, the
effective user ID or the saved set-user-ID.
Precisely the same holds for setegid() with group instead of
user.
RETURN VALUE
On success, zero is returned. On error, −1 is
returned, and errno is set
appropriately.
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Note |
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there are cases where |
ERRORS
- EINVAL
-
The target user or group ID is not valid in this user namespace.
- EPERM
-
In the case of
seteuid(): the calling process is not privileged (does not have theCAP_SETUIDcapability in its user namespace) andeuiddoes not match the current real user ID, current effective user ID, or current saved set-user-ID.In the case of
setegid(): the calling process is not privileged (does not have theCAP_SETGIDcapability in its user namespace) andegiddoes not match the current real group ID, current effective group ID, or current saved set-group-ID.
NOTES
Setting the effective user (group) ID to the saved
set-user-ID (saved set-group-ID) is possible since Linux
1.1.37 (1.1.38). On an arbitrary system one should check
_POSIX_SAVED_IDS.
Under glibc 2.0, seteuid(euid) is equivalent to
setreuid(−1, euid) and hence may change the
saved set-user-ID. Under glibc 2.1 and later, it is
equivalent to setresuid(−1, euid, −1) and hence does not
change the saved set-user-ID. Analogous remarks hold for
setegid(), with the difference
that the change in implementation from setregid(−1, egid) to setresgid(−1, egid, −1) occurred in glibc 2.2
or 2.3 (depending on the hardware architecture).
According to POSIX.1, seteuid() (setegid()) need not permit euid (egid) to be the same value as
the current effective user (group) ID, and some
implementations do not permit this.
C library/kernel differences
On Linux, seteuid() and
setegid() are implemented as
library functions that call, respectively, setreuid(2) and setregid(2).
SEE ALSO
geteuid(2), setresuid(2), setreuid(2), setuid(2), capabilities(7), credentials(7), user_namespaces(7)
COLOPHON
This page is part of release 4.16 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
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Copyright (C) 2001 Andries Brouwer (aebcwi.nl) %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END [should really be seteuid.3] Modified, 27 May 2004, Michael Kerrisk <mtk.manpagesgmail.com> Added notes on capability requirements |