SETUID
Section: Linux Programmer's Manual (2)
Updated: 29 July 1994
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NAME
setuid - set user identity
SYNOPSIS
#include <unistd.h>
int setuid(uid_t uid)
DESCRIPTION
setuid
sets the effective user ID of the current process. If the caller is the
superuser, the real and saved user ID's are also set.
Under Linux,
setuid
is implemented like SYSV with SAVED_IDS.
This allows a setuid (other than root) program to drop all of it's user
privileges, do some un-privileged work, and then re-engage the original
effective user ID in a secure manner.
If the user is root or the program is setuid root, special care must be
taken. The
setuid
function checks the effective uid of the caller and if it is the superuser,
all process related user ID's are set to
uid.
After this has occurred, it is impossible for the program to regain root
privileges.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and
errno
is set appropriately.
ERRORS
- EPERM
-
The user is not the super-user, and
uid
does not match the effective or saved user ID of the calling process.
CONFORMING TO
System V
SEE ALSO
getuid(2), setreuid(2), seteuid(2)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- SEE ALSO
-
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