getprivgrp.2 (2010 09)

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getprivgrp(2) getprivgrp(2)
NAME
getprivgrp(), setprivgrp() - get and set special attributes for group
SYNOPSIS
#include <sys/privgrp.h>
int getprivgrp(struct privgrp_map *grplist);
int setprivgrp(gid_t grpid, const int *mask);
DESCRIPTION
getprivgrp()
The getprivgrp() system call returns a table of the privileged group assignments into a user-supplied
structure. grplist points to an array of structures of type
privgrp_map, associating a group ID with a
privilege mask. Privilege masks are formed by ORing together elements from the access types specified
in
<sys/privgrp.h>
. The array may have gaps in it, distinguished as having a
priv_groupno
field
value of
PRIV_NONE. The group number PRIV_GLOBAL
gives the global privilege mask. Only informa-
tion about groups which are in the user’s group access list, or about the user’s real or effective group ID, is
returned to an ordinary user. The complete set is returned to a user with the SYSATTR privilege.
setprivgrp()
The
setprivgrp() system call associates a kernel capability with a group ID. This allows subletting of
superuser-like privileges to members of a particular group or groups.
setprivgrp() takes two argu-
ments: grpid, the integer group ID, and mask, a mask of permissions. The mask is created by treating
the access types defined in
<sys/privgrp.h>
as bit numbers (using 1 for the least significant bit).
Thus, privilege number 5 would be represented by the bits
1<<(5-1) or 16. More generally, privilege p
is represented by:
mask[((p-1) / BITS_PER_INT)] & (1 << ((
p-1) % BITS_PER_INT))
where BITS_PER_INT is 8*sizeof(mask[0])
given 8 bits per byte. As it is possible to have more
than word-size distinct privileges, mask is a pointer to an integer array of size
PRIV_MASKSIZ.
setprivgrp() privileges include those specified in the file <sys/privgrp.h>
. A process can access
the system call protected by a specific privileged group if it belongs to or has an effective group ID of a
group having access to the system call. All processes are considered to belong to the pseudo-group
PRIV_GLOBAL.
Specifying a grpid of
PRIV_NONE causes privileges to be revoked on all privileged groups that have any
of the privileges specified in mask . Specifying a grpid of PRIV_GLOBAL causes privileges to be granted
to all processes.
The constant
PRIV_MAXGRPS in <sys/privgrp.h>
defines the system limit on the number of groups
that can be assigned privileges. One of these is always the psuedo-group
PRIV_GLOBAL, allowing for
PRIV_MAXGRPS - 1 actual groups.
Only processes with the
SYSATTR privilege can use setprivgrp().
Security Restrictions
Some or all of the actions associated with this system call require the
SYSATTR privilege. Processes
owned by the superuser have this privilege. Processes owned by other users may have this privilege,
depending on system configuration. See privileges (5) for more information about privileged access on sys-
tems that support fine-grained privileges.
RETURN VALUE
getprivgrp() and setprivgrp() return the following values:
0 Successful completion.
-1 Failure. errno is set to indicate the error.
ERRORS
If
getprivgrp() fails, errno is set to one of the following values.
[EFAULT] grplist points to an illegal address. The reliable detection of this error is implemen-
tation dependent.
If
setprivgrp() fails, errno is set to one of the following values.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1