sl_cmp or tl_cmp Subroutine

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Purpose

Compares sensitivity and integrity labels.

Library

Trusted AIX® Library (libmls.a)

Syntax

#include <mls/mls.h>
CMP_RES_T sl_cmp (sl1, sl2)
const sl_t *sl1;
const sl_t *sl2;
CMP_RES_T tl_cmp (tl1, tl2)
const tl_t *tl1;
const tl_t *tl2;

Description

The sl_cmp and tl_cmp subroutines compare two labels. There are three types of relationship between labels: dominance, equality, and non-comparable.

Sensitivity label (SL) comparison is made based on the following conditions:

Dominance:

One SL (L1) dominates another (L2) if and only if the L1 meets the following requirement:
  • The classification in L1 equals or exceeds the classification in L2.
  • The set of compartments in L1 completely contains the set of compartments in L2.

Equality:

One SL (L1) equals another SL (L2) if and only if the L1 meets the following requirement:
  • The classification in L1 equals the classification in L2.
  • The set of compartments in L1 is identical to the set of compartments in L2.

Non-comparable:

Two labels can be disjoint (L1 is not equal to L2, and L1 does not dominate L2, and L2 does not dominate L1). One SL (L1) is non-comparable to another (L2) if the L1 meets the following requirement:
  • The set of compartments in L1 does not completely contain the set in L2 and L2 does not completely contain the set in L1.
Therefore, they are considered disjoint.

Integrity label (TL) comparison is made based on the following conditions:

Dominance:

One TL (L1) dominates another (L2) if and only if the L1 meets the following requirement:
  • The classification in L1 equals or exceeds the classification in L2.

Equality:

One TL (L1) equals another SL (L2) if and only if the L1 meets the following requirement:
  • The classification in L1 equals the classification in L2.

Parameters

Item Description
sl1, sl2 Specifies sensitivity labels to be compared.
tl1, tl2 Specifies Integrity labels to be compared.

Return Values

Item Description
LAB_DOM Indicates that sl1 dominates sl2.
LAB_SAME Indicates that sl1 is identical to sl2.
LAB_IDOM Indicates that sl2 dominates sl1.
LAB_NCMP Indicates that sl1 and sl2 are non-comparable.
LAB_ERR Indicates that the parameter is not valid.
Note: For the tl_cmp subroutine, if either of the integrity labels passed evaluates to the special TL NOTL, the subroutine returns the LAB_DOM value.

Error Codes

Item Description
EINVAL Indicates that the passed-in parameter is NULL.