setreuid, setregid — set real and/or effective user or group ID
#include <sys/types.h> #include <unistd.h>
int
setreuid( |
uid_t | ruid, |
uid_t | euid) ; |
int
setregid( |
gid_t | rgid, |
gid_t | egid) ; |
setreuid
() sets real and
effective user IDs of the current process.
Supplying a value of −1 for either the real or effective user ID forces the system to leave that ID unchanged.
Unprivileged processes may only set the effective user ID to the real user ID, the effective user ID or the saved set-user-ID.
POSIX: It is unspecified whether unprivileged processes may set the real user ID to the real user ID, the effective user ID or the saved set-user-ID.
Linux: Unprivileged users may only set the real user ID to the real user ID or the effective user ID.
Linux: If the real user ID is set or the effective user ID is set to a value not equal to the previous real user ID, the saved set-user-ID will be set to the new effective user ID.
Completely analogously, setregid
() sets real and effective group
ID's of the current process, and all of the above holds with
"group" instead of "user".
On success, zero is returned. On error, −1 is
returned, and errno
is set
appropriately.
The current process is not privileged (Linux: does
not have the CAP_SETUID
capability in the case of setreuid
(), or the CAP_SETGID
capability in the case of
setregid
()) and a change
other than (i) swapping the effective user (group) ID
with the real user (group) ID, or (ii) setting one to
the value of the other or (iii) setting the effective
user (group) ID to the value of the saved set-user-ID
(saved set-group-ID) was specified.
POSIX.1-2001, 4.3BSD (the setreuid
() and setregid
() function calls first appeared in
4.2BSD).
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).
getgid(2), getuid(2), seteuid(2), setgid(2), setresuid(2), setuid(2), capabilities(7)
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