Modern Security Model for Linux Operating Systems Aleksander Zdyb S - - PowerPoint PPT Presentation

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Modern Security Model for Linux Operating Systems Aleksander Zdyb S - - PowerPoint PPT Presentation

May 18, 2023 451 likes •922 views

Aleksander Zdyb Modern Security Model for Linux Operating Systems Aleksander Zdyb S OFTWARE E NGINEER T IZEN P LATFORM S ECURITY a.zdyb@samsung.com https://github.com/azdyb Briefly about security requirements About Tizen operating system

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Modern Security Model for Linux Operating Systems

Aleksander Zdyb

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SOFTWARE ENGINEER TIZEN PLATFORM SECURITY

Aleksander Zdyb

a.zdyb@samsung.com https://github.com/azdyb

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  • Briefly about security requirements
  • About Tizen operating system
  • Dedicated security model
  • Application lifecycle
  • Summary

A.ZDYB | „MODERN SECURITY MODEL FOR LINUX OPERATING SYSTEMS” | BRUSSELS 2016-01-30 | 3/46

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ABOUT SECURITY

REQUIREMENTS

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(CC ) Stiftelsen Elektronikkbransjen (CC ) Intel Free Press (CC ) Sascha Müsse

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  • Classic approach: software acts on behalf of user to full extent
  • Usage of many kinds of privileges is more and more common
  • There is a conflict between privileges granularity

and comfort of usage and administration

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ABOUT TIZEN

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  • Modern operating system

for embedded devices

  • A Linux distribution
  • Developed by Open Source

community

  • Main contribution from Samsung

at the moment

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  • Smartphones, smartwatches,

smart TVs

  • IVI systems (In-Vehicle Infotainment)
  • And more

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wiki.tizen.org

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TIZEN 2.x

  • Commercially released in many

Samsung's devices (smartwatches, smart TVs, smartphones)

  • Security ensured with classic

mechanisms of Linux TIZEN 3.0

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  • Still in developent
  • Works on ODROID XU3 (arm),

MinnowBoard MAX (x86_64) and other architectures

  • Modern, dedicated security model
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SERVICES, RESOURCES

AND PRIVILEGES

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Example services and resources

  • E-mail
  • Camera
  • Networking

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Example services and resources

  • E-mail
  • Camera
  • Networking

Related privileges

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  • Reading, sending messages
  • Contacts preview
  • Taking photos
  • Browsing pictures
  • Accessing remote hosts
  • Usage of different protocols
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Camera Internet Location Contacts Applications Services and resources

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Mapy Kalkulator Przeglądarka Gra

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Camera Internet Location Contacts

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Mapa Kalkulator Przeglądarka Gra

Access control

Applications Services and resources

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DEDICATED SECURITY MODEL

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  • DAC – Discretionary Access Control

(classic access control system)

  • Smack – Simplified Mandatory

Access Control Kernel (one of LSMs)

  • Cynara – dedicated privilege

checker (userspace)

Cynara DAC Smack

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  • Protects resources on filesystem
  • Access control set by owner
  • f the resource
  • Access types: r w x
  • Subject is identified by its id

and groups it belongs to

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Larry Ewing and The GIMP

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  • Protects resources on filesystem
  • Access control set by owner
  • f the resource
  • Access types: r w x
  • Subject is identified by its id

and groups it belongs to

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  • Both object and subject are

identified by their labels

  • Access control is set

by administrator

  • Access types: a r w x t l

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(GFDL) Casey Schaufler

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action

(a r w x l)

  • bject

(label 2)

subject

(label 1)

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Floor (_)

  • Read-only system

directories

  • Kernel’s helper

processes

System

  • /run, /dev, /var/log
  • System services

User

  • Home directories
  • Launcher

and users’ services

Domains are sets of labels with common prefix. There are other labels, like System::Shared, User::Home and more.

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  • System service keeping and

managing security policies

  • Dedicated solution for Tizen 3.0
  • Generic – can be easily deployed

in other Linux distributions

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Application Service Cynara

Extension

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Cynara

Built-in Manifests Privacy Manager Administrator

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LIFECYCLE

OF APPLICATION

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  • Security Manager – service

managing and configuring all of security modules in operating systems

  • Made for Tizen 3.0
  • Can be deployed in other Linux

distributions

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Security Manager is involved in:

  • installing applications – populates

Cynara's database, creates Smack labels for apps

  • launching applications – applies

security context (labels, groups) on behalf of launcher

  • managing security policies –

supports edition of policies by administrator and users (Privacy Manager)

  • managing users

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(CC) Patrick Breen

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Installator Unpacking files Globally For user Security Manager Populating Cynara’s db Creating labels for apps Labelling files

Depends on configuration and privileges

manifest

Installator configures application with help from Security Manager

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Launcher

  • Spawns a process

Cynara

  • SM checks in Cynara what groups

to apply for process

DAC

  • SM sets effective groups to allow access

to some special files (e.g. devices)

Smack

  • SM sets a proper Smack label

for process

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Hi Cynara! Can Maps haz perms to read location? Yep, them can haz dat!

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GPS

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Client User Privilege

Cynara

Client is a Smack label identifying the application One of privileges in Tizen 3.0, e.g. http://tizen.org/privilege/location Service managing protected resource (e.g. GPS location) checks in Cynara, if the access should be granted Application (e.g. maps) run with a proper label and by a given user (e.g. Suzan, uid=1001) requests access GPS location (bound to privilege http://tizen.org/privilege/location) User is an uid

  • f user running

the application

GPS

MAPS

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Hi Cynara! Can Calculator haz Camera, if them want? No, man! No way we gib them dat!

Launcher

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Application (e.g. Camera) run with a proper label and by a given user (e.g. Susan, uid=1001) requests access to device /dev/camera

/dev/camera

Linux checks (DAC) if process belongs to a proper group (e.g. camera_users) Groups are assigned by Security Manager on every launch

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BONUSES

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  • Serving on D-Bus? We’ve got your back
  • Nether – networking access control
  • nice-lad – auditing
  • Vasum – containers

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SUMMARY

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  • Security of embedded systems and privacy of stored data are very important
  • Classic security mechanisms are not enough
  • Security must be taken into account from the very beginning
  • Security doesn't have to be burdensome for developers

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QUESTIONS?

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  • https://wiki.tizen.org/wiki/Main_Page
  • https://wiki.tizen.org/wiki/Security/Overview
  • https://wiki.tizen.org/wiki/Security:Cynara
  • https://wiki.tizen.org/wiki/Security:nice-lad
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  • https://github.com/Samsung/security-manager
  • https://github.com/Samsung/nether
  • https://github.com/Samsung/nice-lad
  • https://github.com/Samsung/vasum
  • https://github.com/Samsung/cynara
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  • https://www.flickr.com/photos/elektronikkbransjen/15523115208/
  • https://www.flickr.com/photos/intelfreepress/8047838494/
  • https://www.flickr.com/photos/saschamuesse/15563157851/
  • https://wiki.tizen.org/wiki/File:IVISimulator2.png
  • http://en.wikipedia.org/wiki/Tux#/media/File:Tux.png
  • http://en.wikipedia.org/wiki/Smack_(software)#/media/File:Smack-tux.svg

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THANKS FOR

LISTENING