Key features
- Open Source (GPL)
- Several well-known and new security models, e.g. MAC, ACL and RC
- Any combination of models possible
- Easily extensible: write your own model for runtime registration
- Support for current kernels
- Stable for production use
What is RSBAC?
RSBAC is a flexible, powerful and fast open source access
control framework for current Linux kernels, which has been in stable production use for
over a year (since version 1.0.9a).
The standard package includes a range of access control models like MAC, RC, ACL (see
below). Furthermore, the runtime registration facility (REG) makes
it easy to implement your own access control model as a kernel module and get it
registered at runtime.
The RSBAC framework is based on the Generalized Framework for Access Control (GFAC) by
Abrams and LaPadula. All security relevant system calls are extended by security
enforcement code. This code calls the central decision component, which in turn calls all
active decision modules and generates a combined decision. This decision is then enforced
by the system call extensions.
Decisions are based on the type of access (request type), the access target and on the
values of attributes attached to the subject calling and to the target to be accessed.
Additional independent attributes can be used by individual modules, e.g. the privacy
module (PM). All attributes are stored in fully protected directories, one on each mounted
device. Thus changes to attributes require special system calls provided.
As all types of access decisions are based on general decision requests, many different
security policies can be implemented as a decision module. Apart from the builtin models
shown below, the optional Module Registration (REG) allows for
registration of additional, individual decision modules at runtime.
In the RSBAC version 1.1.2, the following modules are included. Please note that all
modules are optional. They are described in detail in an extra text.
- MAC
- Bell-LaPadula Mandatory Access Control (compartments limited to a number of 64)
- FC
- Functional Control. A simple role based model, restricting access to security
information to security officers and access to system information to administrators.
- SIM
- Security Information Modification. Only security administrators are allowed to modify
data labeled as security information
- PM
- Privacy Model. Simone
Fischer-Hübner's Privacy Model in its first implementation. See our paper on PM implementation (43K) for the National Information
Systems Security Conference (NISSC 98)
- MS
- Malware Scan. Scan all files for malware on execution (optionally on all file read
accesses or on all TCP/UDP read accesses), deny access if infected. Currently the Linux
viruses Bliss.A and Bliss.B and a handfull of others are detected. See our paper on Approaches to Integrated Malware Detection and Avoidance (34K) for
The Third Nordic Workshop on Secure IT Systems (Nordsec'98)
- FF
- File Flags. Provide and use flags for dirs and files, currently execute_only (files),
read_only (files and dirs), search_only (dirs), secure_delete (files), no_execute (files),
add_inherited (files and dirs) and no_rename_or_delete(files and dirs, no inheritance).
Only security officers may modify these flags.
- RC
- Role Compatibility. Defines 64 roles and 64 types for each target type (file, dir, dev,
ipc, scd, process). For each role, compatibility to all types and to other roles can be
set individually and with request granularity. For administration there is a fine grained
separation-of-duty.
- AUTH
- Authorization enforcement. Controls all CHANGE_OWNER requests for process targets, only
programs/processes with general setuid allowance and those with a capability for the
target user ID may setuid. Capabilities can be controlled by other programs/processes,
e.g. authentication daemons.
- ACL
- Access Control Lists. For every object there is an Access Control List, defining which
subjects may access this object with which request types. Subjects can be of type user, RC
role and ACL group. Objects are grouped by their target type, but have individual ACLs. If
there is no ACL entry for a subject at an object, rights are inherited from parent
objects, restricted by an inheritance mask. Direct (user) and indirect (role, group)
rights are accumulated. For each object type there is a default ACL on top of the normal
hierarchy. Group management has been added in version 1.0.9a.
A general goal of RSBAC design has been to some day reach (obsolete) Orange Book
(TCSEC) B1 level. Now it is mostly targeting to be useful as secure and multi-purposed
networked system, with special interest in firewalls.
Why you need RSBAC
Questions,
tips, etc.
27-Aug-01, -ao