Directions in SELinux Networking

Directions in SELinux Networking

Linux Kernel Networking Summit
Montréal, Canada
July 2005

James Morris <jmorris@redhat.com>

SELinux
●
SELinux provides finegrained, flexible MAC.
●
Subjects and objects are labeled with security
contexts, policy determines interactions.
●
Type Enforcement (TE) model provides an
expressive abstraction of security classes and
their interactions.

Current Status
●
SELinux provides broad coverage across the
kernel (140 hooks).
●
All socketcalls are mediated, provides high level
control over local networking.
●
Protocol specific controls for Netlink, Unix, some
IP (name_bind, name_connect, rudimentary
packet filter).

Networking Directions
●
Performance of IP network controls needs to be
improved.
●
Hit by perpacket lookups for security context of
port and IP addresses.
●
IBM did some work on an RCU cache, needs
further investigation.
●
May be replacing IP packet hooks anyway.

Netfilter/iptables
●
Possibly replace existing IP packet controls with
Netfilter/iptables integration (selipt).
●
More flexible & expressive, makes use of
conntrack, matches, targets etc.
●
Need receiving socket: current code uses
ipt_owner patch.
●
Better to use socket hook work from Patrick
McHardy.

Distributed MAC
●
MAC is currently limited to the local machine.
●
Historically used with MultiLevel Security
(MLS).
●
Typically, each packet is labeled via IP options
(CIPSO, FIPS188).
●
Selopt implemented, dropped for upstream
merge.

Leveraging IPsec
●
Trent Jaeger's implicit labeling work (IBM).
●
Label SAs instead of packets.
●
Draws on previous Flask work.
●
Not MLS or even SELinux specific.
●
Utilizes IPsec services: confidentiality;
authentication; negotiation; automation.

Leveraging IPsec II
●
Hooks into xfrm subsystem.
●
IPsec policies are labeled: only authorized
policies may be used, controlled via SELinux.
●
SA labels must match (existing SA or triggered
negotiation with IKE).
●
Matching packets considered labeled.
●
Policy for unlabeled packets (e.g. ISAKMP).

Leveraging IPsec III
●
Useful for MLS networking, suitable for LSPP
(B1) and beyond.
●
Not compatible with IP options schemes.
●
More generally useful for extending SELinux
across the network.
●
Control communication between processes on
different systems.

Networked Filesystems
●
NSA developed support for NFSv3.
●
Future is NFSv4 with named attributes.
●
SMB desired by some parties.
●
Cluster Filesystems (some OCFS2 work).

Remote Attestation
●
Use of TPM and associated hardware to
cryptographically verify system from boot.
●
IBM Integrity Measurement Architecture (IMA).
●
Requires protocol which queries TPM with
nonce; TPM signs measurement list and nonce.
●
SELinux policy could be used to require that the
remote system is attested before some other
communication.

Cryptographic Policy
●
SELinux policy could be extended to express
more general cryptographic policy.
●
e.g. foo_t file must be stored with X encryption,
and only transmitted by local admin_t to remote
admin_t on trusted hosts with Y encryption and Z
authentication on the wire.
●
May also require use of specific crypto device or
software.

Distributed Policy
●
Mechanism for distributing and synchronizing
policy within a security realm may be useful
when using distributed MAC.

Longer Term
●
General trend toward increasingly high assurance
distributed computing.
●
Interrealm communication. Establishing trust
between different “domains of interpretation” is
very difficult.
●
SE aware firewalling, complicated by Ipsec.

Resources
●
SELinux Enhanced IPTables
http://people.redhat.com/jmorris/selinux/selipt/

●
“Architecture of SELinux Network Access Controls”
http://www.selinuxsymposium.org/2005/presentations/session2/22morris.pdf

●
“Leveraging IPSec for network access control for SELinux”
http://www.selinuxsymposium.org/2005/presentations/session2/23jaeger.pdf

●
Full IBM research report on the above (and more generalized).
Not yet published

●
Ajaya Chitturi's Flask Thesis
http://www.cs.utah.edu/flux/papers/ajaythesisabs.html

Directions in SELinux Networking

More Related Content

What's hot (20)

Similar to Directions in SELinux Networking (20)

More from James Morris (7)

Recently uploaded (20)

Directions in SELinux Networking