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Oracle® Label Security Administrator's Guide
12c Release 1 (12.1)

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13 Releasability Using Inverse Groups

This chapter discusses the Oracle Label Security implementation of releasability using inverse groups.

This chapter contains the following sections:

Introduction to Inverse Groups and Releasability

Inverse groups indicate releasability of information. They are used to mark the dissemination of data. When you add an inverse group to a data label, the data becomes less classified. For example, a user with inverse groups UK and US cannot access data that only has inverse group UK. Adding US to that data makes it accessible to all users with the inverse groups UK and US.

When you assign releasabilities to a user, you mark the communication channel to the user. For data to flow across the communication channel, the data releasabilities must dominate the releasabilities assigned to the user. In other words, releasabilities assigned to a data record must contain all the releasabilities assigned to a user.

The advantage of releasabilities lies in their power to broadly disseminate information. Releasing data to the entire marketing organization becomes as simple as adding the Marketing releasability to the data record.

Comparing Standard Groups and Inverse Groups

Groups in Oracle Label Security identify organizations that own or access data. Like standard groups, inverse groups control the dissemination of information. However, the behavior of inverse groups differs from Oracle Label Security standard group behavior. By default, all policies created in Oracle Label Security use the standard group behavior.

The term, releasabilities is sometimes used to refer to the behavior provided by inverse groups. When you include inverse groups in a data label, the effect is similar to assigning label compartment authorizations to a user. When Oracle Label Security evaluates whether a user can view a row of data assigned to a label with inverse groups, it checks to see whether the data, not the user, has the appropriate group authorizations. It checks whether the data has all the inverse groups assigned to the user. With standard groups, by contrast, Oracle Label Security checks to see whether a user is authorized for at least one of the groups assigned to a row of data.

Consider a policy that contains three standard groups such as, Eastern, Western, and Southern. User1's label authorizations include the groups Eastern and Western. Assuming that User1 has been assigned the appropriate level and compartment authorizations in the policy, then:

  • With standard Oracle Label Security groups, User1 can view all data records that have the group Eastern, or the group Western, or both Eastern and Western.

  • With inverse groups, User1 can only view data records that have, at a minimum, all the groups assigned to the user, that is, both Eastern and Western. User1 cannot view records that have only the Eastern group, only the Western group, or that have no groups at all.

Table 13-1 shows all the rows that User1 can potentially access, given the type of group that is used in the policy.

Table 13-1 Access to Standard Groups and Inverse Groups

If row label contains groups: User1 access with standard groups? User1 access with inverse groups?

None

Y

N

Eastern

Y

N

Western

Y

N

Southern

N

N

Eastern, Western

Y

Y

Eastern, Southern

Y

N

Western, Southern

Y

N

Eastern, Western, Southern

Y

Y


Standard groups indicate ownership of information. In this way, all data pertaining to a certain department can have that department's group in the label. When you add a group to a data label, the data becomes more classified. For example, a user with no groups can access data that has no groups in its label. If you add the group US to the data label, the user can no longer access the data.

How Inverse Groups Work

This section explains how inverse groups are implemented and how they work. It contains these topics:

Implementing Inverse Groups with the INVERSE_GROUP Enforcement Option

When creating an Oracle Label Security policy, the administrator can specify whether the policy can use inverse group functionality to implement releasability. To do this, the administrator specifies INVERSE_GROUP as one of the default_options in the CREATE_POLICY statement.

The INVERSE_GROUP option can be set only at policy creation time. Once a policy is created, this option cannot be changed.

The INVERSE_GROUP option is thus policywide. It cannot be turned on or off when the policy is applied to a table or schema. If you attempt to do so, using the procedure APPLY_TABLE_POLICY or APPLY_SCHEMA_POLICY, then an error will be generated.

While other policy enforcement options can be dropped from a policy, the INVERSE_GROUP policy configuration option cannot be dropped once it is set. To remove the option, you must drop and then re-create the policy.

The administrator can give individual users authorization for one or more inverse groups.

Inverse Groups and Label Components

When an Oracle Label Security policy is created with the inverse group option, the components in the policy label (levels, compartments, and groups) are the same as with standard groups. With inverse groups, however, the user's read groups and write groups have a different meaning and role in data access.

Consider the following policy example, with three levels, one compartment, and three groups:

Table 13-2 Policy Example

Policy Component Abbreviation

Levels:

 

UNCLASSIFIED

UN

CONFIDENTIAL

CON

SECRET

SE

Compartments:

 

FINANCIAL

FIN

Groups:

 
EASTERN
EAS
WESTERN
WES
SOUTHERN
SOU

Two user labels have been assigned, CON:FIN and SE:FIN:EAS,WES

Two data labels have been assigned, CON:FIN:EAS and SE:FIN:EAS

User access to the data differs, depending on the type of group being used:

  • If the policy uses standard groups, then:

    The user with the label CON:FIN cannot read CON:FIN:EAS data.

    The user with the label SE:FIN:EAS,WES can read SE:FIN:EAS data.

  • If the policy has the INVERSE GROUPS policy enforcement option, then:

    The user with the label CON: FIN can read CON:FIN:EAS data.

    The user with the label SE:FIN:EAS,WES cannot read SE:FIN:EAS data.

Computed Labels with Inverse Groups

This section explains how inverse groups affect computed label values. It contains these topics:

Computed Session Labels with Inverse Groups

After the administrator assigns label authorizations to a user, Oracle Label Security automatically computes a number of labels. With inverse groups, these labels are as follows:

Table 13-3 Computed Session Labels with Inverse Groups

Computed Label Definition

Max Read Label

The user's maximum level combined with his or her authorized compartments and the minimum set of inverse groups that should be in the user label (session label)

Max Write Label

The user's maximum level combined with the compartments for which the user has been granted write access. Contains the maximum authorized inverse groups that can be set in any label. The user has write authorizations on all these inverse groups.

Min Write Label

The user's minimum level.

Default Read Label

The default level, combined with compartments and inverse groups that have been designated as default for the user.

Default Write Label

A subset of the default read label, containing the compartments and inverse groups for which the user has been granted write access. However the inverse groups component has no significance as it is the Max Write Groups that is always used for write access.

Default Row Label

The combination of components between the user's minimum write label and the maximum write label, which has been designated as the default for the data label for inserted data. The Inverse groups should be a superset of inverse groups in the default label and a subset of Max Write Groups.


Inverse Groups and Computed Max Read Groups and Max Write Groups

From the computed values in Table 13-3, two sets of groups are identified for label evaluation of read and write access:

Table 13-4 Sets of Groups for Evaluating Read and Write Access

Sets of Groups Meaning

Max Read Groups

Max Read Groups are the groups contained in the Max Read Label, identifying the minimum set of inverse groups that can be set in any user label.

Max Write Groups

Max Write Groups are the groups contained in the Max Write Label, identifying the maximum authorized inverse groups that can be set in any user label. This set of groups is checked at the time of write access, and also when setting session labels.

Note that Max Write Groups is a superset of Max Read Groups.


As shown in Table 13-5, for standard groups you can have READ ONLY and READ/WRITE authorizations; for inverse groups you can have WRITE ONLY and READ/WRITE authorizations.

Table 13-5 Read and Write Authorizations for Standard Groups and Inverse Groups

Type of Group READ ONLY READ/WRITE WRITE ONLY

Standard Groups

The group is present only in Max Read Label, not in Max Write Label.

The group is present in both Max Read Label and Max Write Label.

Not supported

Inverse Groups

Not supported

The group is present in both Max Read Label and Max Write Label.

The group is present only in Max Write Label, not in Max Read Label.


Although Max Read Groups identifies the set of groups contained in the Max Read Label, this value represents the minimum set of inverse groups that can be set. For example:

Max Read Groups: S:C1:G1,G2

Max Write Groups: S:C1:G1,G2,G3,G4,G5

Here, the user can read data that contains at least the two groups listed in Max Read Groups.

Note that in standard groups, there can never be a situation in which there are more groups in the Max Write Label than in the Max Read Label.

Inverse Groups and Hierarchical Structure

Standard groups in Oracle Label Security are hierarchical, so that a group can be associated with a parent group. For example, the EASTERN region can be the parent of two subordinate groups: EAS_SALES, and EAS_HR.

In a policy with standard groups, if the user label has the parent group, then it can access all data of the subordinate groups.

With inverse groups, parent-child relationships are not supported.

Inverse Groups and User Privileges

With inverse groups implemented, the meaning of user privileges remains the same.

When the user has no special privileges, then the read algorithm and the write algorithm are different for standard groups and inverse groups. The differences are described later, in "Algorithm for Read Access with Inverse Groups" and "Algorithm for Write Access with Inverse Groups".

The effect of inverse groups on the COMPACCESS privilege is described later, in "Algorithms for COMPACCESS Privilege with Inverse Groups".

Inverse groups have no impact upon the following user privileges:

  • PROFILE_ACCESS

  • WRITEUP

  • WRITEDOWN

  • WRITEACROSS

Algorithm for Read Access with Inverse Groups

This section describes the algorithm for read access with inverse groups.

To read data in a table with the INVERSE GROUP option in effect, the label evaluation process proceeds from levels to groups to compartments, as illustrated in Figure 13-1, "Read Access Label Evaluation with Inverse Groups". (Note that the current session label is the label being evaluated.)

  1. The user's level must be greater than or equal to the level of data.

  2. The user's label must include all the compartments assigned to the data

  3. The groups in the data label must be a superset of the groups in the user label.

If the user's label passes these tests, then the user can access the data. If not, the user is denied access. Note that if the data label is null or invalid, then the user is denied access.

Note:

This flow diagram is true only when the user has no special privileges.

Figure 13-1 Read Access Label Evaluation with Inverse Groups

Description of Figure 13-1 follows
Description of "Figure 13-1 Read Access Label Evaluation with Inverse Groups"

Algorithm for Write Access with Inverse Groups

This section describes the algorithm for write access with inverse groups.

To write data in a table with the INVERSE GROUP option, the label evaluation process proceeds from levels to groups to compartments, as illustrated in Figure 13-2, "Write Access Label Evaluation with Inverse Groups". (Note that the current session label is the label being evaluated.)

  1. The level in the data label must be greater than or equal to the user's minimum level, and less than or equal to the user's session level.

  2. One of the following conditions must be met:

    The groups in the data label must be a superset of the groups in the user label.

    or

    The user has READ access privilege on the policy.

  3. The user's Max Write Groups must be a superset of the data label groups.

  4. The user label must have write access on all of the compartments in the data label.

Note that if the data label is null or invalid, then the user is denied access.

Note:

This flow diagram is true only when the user has no special privileges.

Figure 13-2 Write Access Label Evaluation with Inverse Groups

Description of Figure 13-2 follows
Description of "Figure 13-2 Write Access Label Evaluation with Inverse Groups"

Algorithms for COMPACCESS Privilege with Inverse Groups

This section describes the algorithms for read and write access with inverse groups, for users who have COMPACCESS privilege.

The COMPACCESS privilege allows a user to access data based on the row's compartments, independent of the row's groups.

  • When compartments exist and access to them is authorized, then the group authorization is bypassed.

  • If a row has no compartments, then access is determined by the inverse group authorizations.

Figure 13-3, "Read Access Label Evaluation: COMPACCESS Privilege and Inverse Groups" and Figure 13-4, "Write Access Label Evaluation: COMPACCESS Privilege and Inverse Groups" show the label evaluation process for read access and write access for a user with the COMPACCESS privilege. If the data label is null or invalid, then the user is denied access.

(Note that the current session label is the label being evaluated.)

Figure 13-3 Read Access Label Evaluation: COMPACCESS Privilege and Inverse Groups

Description of Figure 13-3 follows
Description of "Figure 13-3 Read Access Label Evaluation: COMPACCESS Privilege and Inverse Groups"

Figure 13-4 Write Access Label Evaluation: COMPACCESS Privilege and Inverse Groups

Description of Figure 13-4 follows
Description of "Figure 13-4 Write Access Label Evaluation: COMPACCESS Privilege and Inverse Groups"

Session Labels and Inverse Groups

This section describes how inverse groups affect session labels and row labels.

Setting Initial Session/Row Labels for Standard or Inverse Groups

The use of inverse groups affects the behavior of Oracle Label Security procedures that determine the session label. The SA_USER_ADMIN.SET_DEFAULT_LABEL and SA_USER_ADMIN.SET_ROW_LABEL procedures set the user's initial session label and row label, respectively, to the one specified.

Standard Groups: Rules for Changing Initial Session/Row Labels

A user's default session label can be changed using SA_USER_ADMIN.SET_DEFAULT_LABEL. In the case of standard groups, the default session label can be set to include any groups in the authorized list, as long as the current default row label will still be dominated by the new write label. That is, the row label will have the same or fewer standard groups than the new write label.

The same rule applies for SA_USER_ADMIN.SET_ROW_LABEL.

Inverse Groups: Rules for Changing Initial Session/Row Labels

In the case of inverse groups, the default session label can be set to include any groups in the authorized list, as long as the current default row label will still be dominated by the new write label. That is, the row label will have the same or more inverse groups than the new write label.

The same rule applies for SA_USER_ADMIN.SET_ROW_LABEL.

Setting Current Session/Row Labels for Standard or Inverse Groups

The use of inverse groups affects the behavior of the SA_SESSION.SET_LABEL and SA_SESSION.SET_ROW_LABEL procedures, which can be used to set the user's current session label and row label, respectively.

Standard Groups: Rules for Changing Current Session/Row Labels

With standard groups, the SA_SESSION.SET_LABEL procedure can be used to set the session label to include any groups in the user's authorized group list. (Subgroups of authorized groups are implicitly included in the authorized list.) Note that if you change the session label, then this may affect the value of the session's row label.

Use the SET_ROW_LABEL procedure to set the row label value for the current database session. The compartments and groups in the label must be a subset of compartments and groups in the session label to which the user has write access.

Inverse Groups: Rules for Changing Current Session/Row Labels

With inverse groups, the addition of groups to the session label decreases a user's ability to access sensitive data with fewer groups. The removal of groups enables the user to access more sensitive information. So, the user should be allowed to add groups to the session label, as long as Max Read Groups is a subset of the groups in the session label, and Max Write Groups is a superset of groups in the session label. The same restriction applies when a user removes groups from the session label.

Note that there are no subgroups of authorized groups when using inverse groups. This is because parent groups are not allowed in policies using inverse groups.

Use the SET_ROW_LABEL procedure to set the row label value for the current database session. The compartments in the label must be a subset of compartments in the session label to which the user has write access.

The user is allowed to add inverse groups to the row label, as long as the session label inverse groups are a subset of the row label inverse groups, and Max Write Groups is a superset of inverse groups in the row label.

For example:

  • If the user has the inverse groups UK and US as his Max Read Groups, and UK,US,CAN as his Max Write Groups. The user can set his session label to C:ALPHA:UK,US,CAN but not to C:ALPHA:UK.

  • If the user has the inverse group UK as his Max Read Groups, and UK,CAN as his Max Write Groups.assigned to him. The user can set the session label to C:ALPHA:UK,CAN but cannot change it to either C:ALPHA or C:ALPHA:UK,US,CAN.

Examples of Session Labels and Inverse Groups

This section presents examples to illustrate the use of inverse groups.

Inverse Groups Example 1

Consider a User1, of a policy implementing inverse groups, with the following labels:

Table 13-6 Labels for Inverse Groups Example 1

Name Definition

Max Read Label

SE:ALPHA,BETA:G1,G2

Max Write Label

SE:ALPHA:G1,G2,G3

Default Read Label

SE:ALPHA,BETA:G1,G2

Default Write Label

SE:ALPHA:G1,G2

Default Row Label

SE:ALPHA:G1,G2

From which the following values are derived:

 

Max Read Groups

G1,G2

Max Write Groups

G1,G2,G3


The following conclusions can be drawn:

  • User1 can update data with label SE:ALPHA:G1,G2 as well as data with label SE:ALPHA:G1,G2,G3. User1 cannot, however, update label SE:ALPHA:G1.

    If standard groups were being used, rather than inverse groups, then User1 could update data with label SE:ALPHA:G1.

  • Data that User1 inserts has the label SE:ALPHA:G1,G2. (This is the same as with standard groups.)

  • If User1 leaves the default label as is, and sets the row label to SE:ALPHA:G1,G2,G3, then user1 will insert SE:ALPHA:G1,G2,G3 in new rows of data that is written. (In standard groups, User1 can never set more groups in the row label than in the default label.)

Inverse Groups Example 2

Consider a User01, of a policy implementing inverse groups, with the following labels:

Table 13-7 Labels for Inverse Groups Example 2

Name Definition

Max Read Label

C:ALPHA:

Max Write Label

C:ALPHA:G1,G2,G3

Default Read Label

C:ALPHA:

Default Write Label

C:ALPHA:

Default Row Label

C:ALPHA:

From which the following values are derived:

 

Max Read Groups

(an empty set)

Max Write Groups

G1,G2,G3


The following conclusions can be drawn:

  • User01 can update any data with level C, compartment ALPHA, and any combination of groups G1, G2, G3, or no groups. User01 inserts the label C:ALPHA: in new data that User01 writes.

  • User02, who has Max Read Groups of G1,G2 or G1,G3, and so on, will not be able to view the data written by User01. This is because User01's Default Row Label contains no groups.

  • User01 can choose to set inverse groups in the row label, as long as the inverse groups in the session label dominates the row label (that is, User01's session label contains the same or fewer groups than contained in the row label).

    This is true because the row label must have at least the groups in the session label, and can at most have the Maximum Write Groups. If the session label is G1, then you can set the groups in the row label from G1 to the Max Write Groups (G1,G2,G3).

  • If User01 sets his session label and row label to C:ALPHA:G1:G2:G3, then his data becomes accessible to anyone who has any combination of G1,G2,G3 in his Max Read Groups.

Changes in Behavior of Procedures with Inverse Groups

When the INVERSE_GROUP option is specified at the time the policy is created, a change occurs in the algorithms that determine the read and write access of the user to labeled data. This section describes how inverse groups affect the behavior of the following procedures:

SA_SYSDBA.CREATE_POLICY with Inverse Groups

The CREATE_POLICY procedure under the SA_SYSDBA package creates the policy, defines an optional policy-specific column name, and specifies a set of default policy options. With inverse group support the, user has one more policy enforcement option, INVERSE_GROUP. For example:

PROCEDURE CREATE_POLICY (
 HR IN VARCHAR2,
 SA_LABEL IN VARCHAR2 DEFAULT NULL,
 INVERSE_GROUP IN VARCHAR2 DEFAULT NULL);

SA_SYSDBA.ALTER_POLICY with Inverse Groups

The ALTER_POLICY procedure under the SA_SYSDBA package enables you to change a policy's default enforcement options, except for the INVERSE_GROUP option. Once a policy is configured for inverse groups, it cannot be changed. You can also change the column names associated with an OLS policy.

SA_USER_ADMIN.ADD_GROUPS with Inverse Groups

The ADD_GROUPS procedure adds groups to a user, indicating whether the groups are authorized for write as well as read.

The type of access authorized depends on the access_mode parameter.

Table 13-8 Access Authorized by Values of access_mode Parameter

Access_Mode Parameter Meaning

READ_WRITE

Indicates that write is authorized. (That is, the group is contained in both Max Read Groups and Max Write Groups.)

WRITE_ONLY

Indicates that the group is contained in Max Write Groups and not in Max Read Groups

access_mode

If access_mode is set to READ_WRITE, then the group is added to both Max Read Groups and Max Write Groups.

If access_mode is set to SA_UTL.WRITE_ONLY, then the group is added only to the Max Write Groups.

If access_mode is NULL, then it is set to SA_UTL.READ_WRITE.

in_def

Specifies whether these groups should be in the default groups (Y/N).

If in_def is NULL, then it will be set to Y or N as follows:

If access mode is READ_WRITE, in_def is set to Y.

If access mode is WRITE_ONLY, in_def is set to N.

in_row

Specifies whether these groups should be in the row label (Y/N), using the identical criteria as for in_def.

However, if in_def is Y, then in_row must also be Y.


Note that if in_def is Y in a row, then in_row must also be set to Y, but not the other way round.

The same is the case with the in_row field.

SA_USER_ADMIN.ALTER_GROUPS with Inverse Groups

The ALTER_GROUPS procedure changes the write access, the default label indicator, and the row label indicator for each of the groups in the list.

The behavior of inverse groups is the same as described in the case of ADD_GROUPS.

SA_USER_ADMIN.SET_GROUPS with Inverse Groups

The SET_GROUPS procedure assigns groups to a user and identifies default values for the user's session label and row label.

Inverse groups are handled differently than standard groups, as follows:

Table 13-9 Assigning Groups to a User

Group Set Name Meaning

read_groups

A comma-delimited list of groups that would be Max Read Groups

write_groups

A comma-delimited list of groups that would be Max Write Groups. It must be a superset of read_groups.

If write_groups is NULL, then they are set to read_groups.

def_groups

Specifies the default groups. It should at least have read_groups, and write_groups should be a superset of def_groups.

If def_groups is NULL, then they are set to the read_groups.

row_groups

Specifies the row groups. It should at least have the def_groups and should be a subset of max write groups.

If row_groups is NULL, then they are set to the def_groups, because for inverse groups, all def_groups are also in write_groups.


SA_USER_ADMIN.SET_USER_LABELS with Inverse Groups

The SET_USER_LABELS procedure sets the user's levels, compartments, and groups using a set of labels, instead of the individual components.

Inverse groups are handled differently than standard groups, as follows:

Table 13-10 Inverse Group Label Definitions

Name Definition

max_read_label

Specifies the label string to be used to initialize the user's maximum authorized read label. Composed of the user's maximum level, compartments authorized for read access, and if inverse groups, minimum set of groups that can be set in any label.(Max Read Groups)

max_write_label

Specifies the label string to be used to initialize the user's maximum authorized write label. Composed of the user's maximum level, compartments authorized for write access, and if inverse groups, the maximum authorized groups that can be set in any label (Max Write Groups). All the inverse groups in this have write authorization also. It should be a superset of groups in max_read_label. If max_write_label is not specified, then it is set to max_read_label.

def_label

Specifies the label string to be used to initialize the user's session label, including level, compartments, and groups (a subset of max_read_label). If default_label is not specified, then it is set to max_read_label. For inverse groups, component it should at least have the groups in max_read_label, and groups in max_write_label should be a superset of the groups in the def_label.

row_label

Specifies the label string to be used to initialize the program's row label. Includes levels, compartments, and groups: subsets of max_write_label and def_label. If row_label is not specified, then it is set to def_label, with only the compartments and groups authorized for write access. The inverse groups component is set to the same as that in def_label if the row_label is not specified. The inverse groups in row label should at least be those in default label and should be a subset of Max Write Groups.


SA_USER_ADMIN.SET_DEFAULT_LABEL with Inverse Groups

The SET_DEFAULT_LABEL procedure sets the user's initial session label to the one specified.

All the rules mentioned for setting inverse groups component of session label mentioned in "Session Labels and Inverse Groups" are applicable here.

SA_USER_ADMIN.SET_ROW_LABEL with Inverse Groups

Use the SET_ROW_LABEL procedure to set the user's initial row label to the one specified.

When specifying the row_label, the inverse groups component must contain at least all the inverse groups in def_label and should be a subset of Max Write Groups.

SA_COMPONENTS.CREATE_GROUP with Inverse Groups

Use the CREATE_GROUP procedure to create a group and specify its short name and long name, and optionally a parent group.

With inverse groups, the parent_name field should always be NULL. If the user specifies a value for this field, then an error message is displayed, indicating that the group hierarchy is disabled.

SA_COMPONENTS.ALTER_GROUP_PARENT with Inverse Groups

This function is disabled for policies with the inverse group option. An error message is displayed if the user calls this function.

SA_SESSION.SET_LABEL with Inverse Groups

Use the SET_LABEL procedure to set the label of the current database session.

See Also:

Syntax for "SA_SESSION.SET_LABEL Procedure".

For the current user, this procedure follows the same rules for setting the session label as does the sa_user_admin.set_user_label function.

SA_SESSION.SET_ROW_LABEL with Inverse Groups

Use the SET_ROW_LABEL procedure to set the default row label value for the current database session.

For the current user, this procedure follows the same rules for setting the row label as does the sa_user_admin.set_row_label function.

LEAST_UBOUND with Inverse Groups

The LEAST_UBOUND (LUBD) function returns a character string label that is the least upper bound of label1 and label2 that is, the one label that dominates both.

With standard groups, the least upper bound is the highest level, the union of the compartments in the labels, and the union of the groups in the labels.

With inverse groups, the least upper bound is the highest level, the union of the compartments in the labels, and the intersection of the inverse groups in the labels.

For example, with inverse groups, the least upper bound of HIGHLY_SENSITIVE:ALPHA:G1,G2 and SENSITIVE:BETA:G1 is HIGHLY_SENSITIVE:ALPHA,BETA:G1.

GREATEST_LBOUND with Inverse Groups

The GREATEST_LBOUND (GLBD) function can be used to determine the lowest label of the data that can be involved in an operation, given two different labels. It returns a character string label that is the greatest lower bound of label1 and label2.

With standard groups, the greatest lower bound is the lowest level, and the intersection of the compartments in the labels and the groups in the labels.

With inverse groups, the greatest lower bound is the lowest level, and the intersection of the compartments in the labels and the union of inverse groups in the labels.

For example, with inverse groups the greatest lower bound of HIGHLY_SENSITIVE:ALPHA:G1,G3 and SENSITIVE::G1 is SENSITIVE:G1,G3

Dominance Rules for Labels with Inverse Groups

Dominance rules for Oracle Label Security with standard groups can be summarized as follows:

A user label dominates a data label if:

  • User level is greater than or equal to the data level

  • User compartments are a superset of the data compartments

  • User groups intersects (have at least one group from) the data groups

Dominance rules for Oracle Label Security with inverse groups can be summarized as follows:

A user label dominates a data label if:

  • User level is greater than or equal to the data level

  • User compartments are a superset of the data compartments

  • Data groups are a superset of user groups