NAME
privgrp — format of privileged values
DESCRIPTION
setprivgrp()
sets a mask of privileges, and
getprivgrp()
returns an array of structures
giving privileged group assignments on a per-group-ID
basis (see
getprivgrp(2)).
<privgrp.h>
contains the constants and structures needed
to deal with these system calls, and contains:
/*
* Privileged group definitions --
* the numeric values may vary between implementations.
*/
#define PRIV_RTPRIO 1
#define PRIV_MLOCK 2
#define PRIV_CHOWN 3
#define PRIV_LOCKRDONLY 4
#define PRIV_SETRUGID 5
/* Maximum number of privileged groups in system */
#define PRIV_MAXGRPS 32
/*
* Size of the privilege mask,
* based on largest numbered privilege
*/
#define PRIV_MASKSIZ 1
/*
* Structure defining the privilege mask
*/
struct privgrp_map {
int priv_groupno;
unsigned int priv_mask[PRIV_MASKSIZ];
};
Privileges are as follows:
- PRIV_RTPRIO
Allows access to the
rtprio()
system call (see
rtprio(2)).
- PRIV_MLOCK
Allows access to the
plock()
system call (see
plock(2)).
- PRIV_CHOWN
Allows access to the
chown()
system calls (see
chown(2)).
- PRIV_LOCKRDONLY
Permits the use of the
lockf()
system call for setting locks on files open for reading only (see
lockf(2)).
- PRIV_SETRUGID
Permits the use of the
setuid()
and
setgid()
system calls for changing respectively the real user
ID
and real group
ID
of a process (see
setuid(2)).
Privileges are described in a multi-word mask.
The value of the
#define
for each privilege is interpreted as a bit index (counting from 1).
Thus a group-id can have several different privileges
associated with it by having different bits
ORed into the mask.
The system is configured with a specified maximum number
of groups with special privileges.
PRIV_MAXGRPS
defines this maximum.
Of this maximum, one is reserved for global privileges
(granted to all processes),
and the remainder can be assigned to actual group-ids.
PRIV_MASKSIZ
defines the size of the multi-word mask used
in defining privileges associated with a group-ID.
Privileges are returned to the user from the
getprivgrp()
system call in an array of structures of type
struct privgrp_map.
The structure associates a multi-word mask with a group-ID.
