Common Event Flag Clusters

If both a Table of Contents and Search form are not displayed in separate frames along with this one, you may wish to redisplay this book in a frameset, beginning with the first page.

HP OpenVMS Guide to System Security

Security for the User

Descriptions of Object Classes

Capabilities

Devices

Common Event FlagClusters

A common event flag cluster is a set of 32 event flags thatenable cooperating processes to post event notifications to eachother.

Event flags in the cluster can be set or cleared to indicatethe occurrence of an event. All event flags are contained withinclusters of 32 event flags, and each process has access to fourclusters (numbered 0 through 3). Two of the clusters are local toa single process. Event flag clusters 2 and 3 are called commonevent flag clusters and are used for interprocess synchronization.A subject may be associated with up to two common event flag clusters.Each common event flag in a cluster is referenced by an event flagnumber.

NamingRules

The name of the object is whatever character string was suppliedas an argument to the Associate Common Event Flag Cluster systemservice ($ASCEFC). Remember that common event flag cluster namesare qualified by your UIC group number.

Typesof Access

The common event flag cluster class supports the followingtypes of access:

Associate
Gives a process the rightto establish an association with the named cluster so the processcan access event flags.

Delete
Gives a process the rightto mark a permanent event flag cluster for deletion with the DeleteCommon Event Flag Cluster ($DLCEFC) system service. The actual deletionoccurs once all processes disassociate from the cluster.

Control
Gives you the right to modify the protectionelements of the common event flag cluster.

TemplateProfile

The common event flag cluster class provides one templateprofile. Although the template assigns an owner UIC of [0,0], thisvalue is only temporary. As soon as the object is created, the operatingsystem replaces a 0 value with the value in the corresponding fieldof the creating process's UIC.

Template Name Owner UIC Protection Code

DEFAULT
[0,0]
S:AD,O:AD,G:A,W

Template Name	Owner UIC	Protection Code
DEFAULT	[0,0]	S:AD,O:AD,G:A,W

When the process creating the common event flag cluster suppliesa prot argument to $ASCEFC thathas a value of 1, then the system modifies the template so the processUIC is the owner, and the protection code denies group access.

PrivilegeRequirements

Creation of a permanent common event flag cluster requiresthe PRMCEB privilege. This privilege also grants delete access forpermanent clusters.

Kinds of Auditing Performed

The system can audit the following types of events:

Event Audited When Audit Occurs

Creation
When the first process toassociate with a particular cluster calls $ASCEFC

Access
Whenever subsequent callersto $ASCEFC associate with the cluster

Deaccess
When a process calls $DACEFCor associates with another cluster or at image rundown

Deletion
When the process calls $DLCEFC

Event Audited	When Audit Occurs
Creation	When the first process toassociate with a particular cluster calls $ASCEFC
Access	Whenever subsequent callersto $ASCEFC associate with the cluster
Deaccess	When a process calls $DACEFCor associates with another cluster or at image rundown
Deletion	When the process calls $DLCEFC

Permanenceof the Object

A common event flag cluster and its security profile needto be reset each time a system starts up.

Capabilities

Devices

Associate	Gives a process the rightto establish an association with the named cluster so the processcan access event flags.
Delete	Gives a process the rightto mark a permanent event flag cluster for deletion with the DeleteCommon Event Flag Cluster ($DLCEFC) system service. The actual deletionoccurs once all processes disassociate from the cluster.
Control	Gives you the right to modify the protectionelements of the common event flag cluster.