Secure Architecture and Secure Architecture and Implementation of - - PowerPoint PPT Presentation

Secure Architecture and Secure Architecture and Implementation of Implementation of Xen Xen on ARM

• n ARM

for Mobile Devices for Mobile Devices

Sang Sang-

• bum

bum Suh Suh sbuk.suh@samsung.com sbuk.suh@samsung.com SW Laboratories SW Laboratories CTO, Samsung Electronics CTO, Samsung Electronics April 17, 2007 April 17, 2007

Presented at Presented at Xen Xen Summit Spring 2007, IBM TJ Watson Summit Spring 2007, IBM TJ Watson

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SW Laboratories, CTO, Samsung Electronics SW Laboratories, CTO, Samsung Electronics

Contributor Contributor

Sang Sang-

• bum

bum Suh Suh Joo Joo-

• Young Hwang

Young Hwang Sung Sung-

• min Lee

min Lee Sungkwan Sungkwan Heo Heo Sangdok Sangdok Mo Mo ChanJu ChanJu Park Park Seong Seong-

• Yeol

Yeol Park Park Jong Jong-

• Tae Kim

Tae Kim Bokdeuk Bokdeuk Jeong Jeong Chul Chul ryun ryun Kim Kim Jaemin Jaemin Ryu Ryu Jaera Jaera Lee Lee Mikhail Mikhail Pozhenko Pozhenko

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Agenda Agenda

Requirements for Beyond 3G Mobile Device Requirements for Beyond 3G Mobile Device Goal and Approach Goal and Approach Xen Xen on ARM

• n ARM

Xen Xen on ARM Architecture

• n ARM Architecture

System Virtualization System Virtualization System Boot Operation System Boot Operation

Security Security

Security Architecture and Its Components Security Architecture and Its Components Implementation: Status Implementation: Status

Conclusions and Future Work Conclusions and Future Work Appendix Appendix

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Requirements Requirements for Beyond 3G Mobile Devices for Beyond 3G Mobile Devices

High High-

• level Requirements

level Requirements

End user: Secure and reliable mobile terminals for mobile Intern End user: Secure and reliable mobile terminals for mobile Internet et services using services using WiBro WiBro Manufacturer: Robustness though complexity of devices gets Manufacturer: Robustness though complexity of devices gets increased increased Contents provider: Protection of IP rights in end Contents provider: Protection of IP rights in end-

• user terminals

user terminals Carrier companies: Open and Secure Mobile Platform Carrier companies: Open and Secure Mobile Platform

OSTI (Open Secure Terminal Initiative): NTT OSTI (Open Secure Terminal Initiative): NTT DoCoMo DoCoMo, Intel , Intel

Expected Beyond 3G Environments

m-Commerce m-Commerce Downloadable Application Downloadable Application

I nternet/ Cellular I ntegration

Needs

Security, Reliability

(Secure Terminal)

Robustness, Time-to-market

VoIP VoIP

• Apps. & Services

CPU > 500 MIPS CPU > 500 MIPS Memory > 64MB Memory > 64MB High-speed

(10~ 100Mbps),

Multi-mode Modem High-speed

(10~ 100Mbps),

Multi-mode Modem

User Manufacturer

U-Health U-Health Web Browsing Web Browsing Internet Banking Internet Banking Multimedia Service Multimedia Service Mobile 3D Game Mobile 3D Game Component Reusability Component Reusability

System

Multi- function Multi- function

System Complexity

Beyond 3G environments and Needs

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Threats to Mobile Devices Threats to Mobile Devices

According to McAfee, threats to mobile devices will According to McAfee, threats to mobile devices will continue to grow in 2007 continue to grow in 2007

The number of The number of malware malware created for Windows CE/Mobile created for Windows CE/Mobile and and Symbian Symbian was expected to reach 726 by the end of 2006, was expected to reach 726 by the end of 2006, from an estimated 226 at the end of 2005 [KAW06] from an estimated 226 at the end of 2005 [KAW06]

Attacks on mobile banking and trading Attacks on mobile banking and trading

Steals financial data and sends them to a remote attacker Steals financial data and sends them to a remote attacker Examples [GOS06] Examples [GOS06]

StealWar StealWar Worm (2006), Worm (2006), Flexispy Flexispy Trojan (2006), Trojan (2006), Brador Brador Backdoor (2004) Backdoor (2004)

Denial of service ( Denial of service (DoS DoS) attacks ) attacks

Inappropriate execution of instructions consuming system Inappropriate execution of instructions consuming system resources (e.g., memory, CPU, battery), resetting a system resources (e.g., memory, CPU, battery), resetting a system Examples [GOS06] Examples [GOS06]

Cabir Cabir Worm (2004) Worm (2004), , CommWarrior CommWarrior Worm (2005), Worm (2005), Skulls Trojan Skulls Trojan (200 (2004 4) ), , Mobler.a Mobler.a Worm Worm (200 (2006 6) ), , Cxoever Cxoever Worm (2006) Worm (2006)

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H/W

OS

App1 App2 App3

VMM

OS m-Wallet Client App.

m-Wallet Server

(Trusted Server) Secure Channel

Secure Domain

Non-trusted Servers

• n Internet

Unstable or Malicious App. OTA (over-the-air)

• app. download

Non-secure Domain

H/W

OS

App1 App2 App3 m-Wallet Client App.

m-Wallet Server

(Trusted Server) Secure Channel Non-trusted Servers

• n Internet

Unstable or Malicious App. OTA (over-the-air)

• app. download

Without VMM With VMM

* VMM = Virtual Machine Monitor

Typical User Scenario Typical User Scenario

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Features for Secure Mobile Devices Features for Secure Mobile Devices

Low Low-

• overhead system virtualization
• verhead system virtualization

Separation of guest domains Separation of guest domains Hot plug Hot plug-

• in/

in/-

• out of guest domains
• ut of guest domains

Secure boot Secure boot Secure storage Secure storage Access control Access control

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Agenda Agenda

Requirements for Beyond 3G Mobile Device Requirements for Beyond 3G Mobile Device Goal and Approach Goal and Approach Xen Xen on ARM

• n ARM

Xen Xen on ARM Architecture

• n ARM Architecture

System Virtualization System Virtualization System Boot Operation System Boot Operation

Security Security

Security Architecture and Its Components Security Architecture and Its Components Implementation: Status Implementation: Status

Conclusions and Future Work Conclusions and Future Work Appendix Appendix

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Goal and Approach Goal and Approach

Goal Goal

Light Light-

• weight secure virtualization technology for

weight secure virtualization technology for beyond 3G mobile devices beyond 3G mobile devices

Approach Approach

Design and implementation of Design and implementation of

VMM on ARM using VMM on ARM using Xen Xen architecture architecture

Security features using Security features using Xen Xen on ARM:

• n ARM:

guaranteeing confidentiality, integrity, and availability guaranteeing confidentiality, integrity, and availability

Deliverables Deliverables

VMM: Secure VMM: Secure Xen Xen on ARM

• n ARM

Dom0, Dom0, DomU DomU: Para : Para-

• virtualized ARM Linux

virtualized ARM Linux-

• 2.6.11

2.6.11 kernel/ device drivers kernel/ device drivers

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Application Application Application Application

Architecture: Secure Architecture: Secure Xen Xen on ARM

• n ARM

CPU CPU

Application Application Application Application

VM Interface VM Interface VM Interface VM Interface Peripheral Devices Peripheral Devices Peripheral Devices Peripheral Devices Back Back-

• end Drivers

end Drivers Front Front-

• end Drivers

end Drivers Native Drivers Native Drivers

Resource Resource Allocator Allocator Domain Manager Domain Manager Access Control Access Control

Hardware Hardware Secure Secure Xen Xen on ARM

• n ARM

Domain Domain

System Memory System Memory Flash Memory Flash Memory

Dom 0 Dom 0 Dom U Dom U

Application Application

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Development Environments Development Environments

HW and SW Environments HW and SW Environments

A Reference System for Implementation A Reference System for Implementation

SW SW

Xen Xen : Xen : Xen-

• 3.0.2

3.0.2 Linux : ARM Linux Linux : ARM Linux-

• 2.6.11

2.6.11 GUI : GUI : Qtopia Qtopia

HW HW

Processor : ARM Processor : ARM-

• 9 266Mhz (

9 266Mhz (Freescale Freescale i.MX21) i.MX21) Memory : 64MB Memory : 64MB Flash : NOR 32MB / NAND 64MB Flash : NOR 32MB / NAND 64MB LCD : 3.5 inch LCD : 3.5 inch Network : CS8900A 10Base Network : CS8900A 10Base-

• T Ethernet Controller

T Ethernet Controller

Development Environments Development Environments

OS : Fedora Core 6 OS : Fedora Core 6 Cross Cross-

• compiler:

compiler: Montavista Montavista ARM GCC 3.3.1 ARM GCC 3.3.1 Debugger : Trace32 ICD (In Circuit Debugger) Debugger : Trace32 ICD (In Circuit Debugger)

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Agenda Agenda

Requirements for Beyond 3G Mobile Device Requirements for Beyond 3G Mobile Device Goal and Approach Goal and Approach Xen Xen on ARM

• n ARM

Xen Xen on ARM Architecture

• n ARM Architecture

System Virtualization System Virtualization System Boot Operation System Boot Operation

Security Security

Security Architecture and Its Components Security Architecture and Its Components Implementation: Status Implementation: Status

Conclusions and Future Work Conclusions and Future Work Appendix Appendix

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Application Application Application Application

Xen Xen on ARM Architecture

• n ARM Architecture

CPU CPU

Application Application Application Application

VM Interface VM Interface VM Interface VM Interface Peripheral Devices Peripheral Devices Peripheral Devices Peripheral Devices Back Back-

• end Drivers

end Drivers Front Front-

• end Drivers

end Drivers Native Drivers Native Drivers Domain Domain Scheduler Scheduler System Event Manager System Event Manager Domain Create/Destroy Domain Create/Destroy Memory Memory Manager Manager Inter Inter-

• domain Comm.

domain Comm.

Hardware Hardware Xen Xen on ARM

• n ARM

Domain Domain

System Memory System Memory Flash Memory Flash Memory

Dom 0 Dom 0 Dom U Dom U

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CPU Virtualization (1/2) CPU Virtualization (1/2)

Physically two privilege modes (User mode and Physically two privilege modes (User mode and Supervisor mode) in ARM CPU. However, Supervisor mode) in ARM CPU. However,

Supervisor mode is assigned to Supervisor mode is assigned to Xen Xen mode mode User mode is split into two logical modes (kernel and user User mode is split into two logical modes (kernel and user process of Linux) process of Linux) Address space protection between kernel mode and user Address space protection between kernel mode and user process mode is guaranteed by process mode is guaranteed by ARM ARM domain access domain access control mechanism control mechanism. .

Xen Mode Logical mode split Virtualized CPU modes Virtualized CPU modes

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CPU Virtualization (2/2) CPU Virtualization (2/2)

Exception Exception Handling

Handling

Para Para-

• virtualization of system calls.

virtualization of system calls.

System calls are implemented with software interrupt. System calls are implemented with software interrupt. In In Xen Xen on ARM, system calls are interpreted by

• n ARM, system calls are interpreted by Xen

Xen

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User Process User Process User Process User Process User Process User Process

Memory Virtualization (1/3) Memory Virtualization (1/3)

Memory Map Memory Map

Xen Xen and guest domain (kernel + user process) are and guest domain (kernel + user process) are mapped on a same virtual address space. mapped on a same virtual address space.

Guest Domain Guest Domain Guest Domain Guest Domain Xen Xen Guest Domain 1 Guest Domain 1

0x00000000 0xFF000000 0xFFFFFFFF

Guest Domain 0 Guest Domain 0 Xen Xen Physical Address Space (Freescale i.MX21) Virtual Address Space Kernel Kernel User Process User Process Guest Domain Virtual Address Space

0xC0000000 0xC0200000 0xC2000000 0xC4000000 0x00000000 0xC0000000 0xFEFFFFFF

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Memory Virtualization (2/3) Memory Virtualization (2/3)

Domain Access Control is used to prevent a user Domain Access Control is used to prevent a user process from accessing to address space of kernel process from accessing to address space of kernel in ARM CPU user mode. in ARM CPU user mode.

Kernel Mode : D0, D1, D2 enabled Kernel Mode : D0, D1, D2 enabled User Process Mode: D0, D2 enabled, D1 disabled User Process Mode: D0, D2 enabled, D1 disabled

Kernel Kernel Xen Xen User User Process Process

Virtual Address Space ARM Domain (Dynamic)

D0 D1 D2

X X

Page Table Access Permission Field (static)

S: RW, U: No Access

* S : ARM Supervisor mode U : ARM User mode

S: RW, U: RW S: RW, U: RW

00 00 01 01 10 10 11 11 Bit Bit Field Field No Access No Access (Disabled) (Disabled) U Use page table access se page table access permission field. permission field. Client Client (Enabled) (Enabled) Reserved Reserved No access control No access control Manager Manager Comments Comments Access Access

ARM Domain access bit assignments [ARM01]

D3 ~ D15 : reserved for future use.

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Memory Virtualization (3/3) Memory Virtualization (3/3)

Keep Keep Xen Xen address translation info from being address translation info from being flushed. flushed.

After page table changes (domain/process switching), After page table changes (domain/process switching), TLB entries are flushed explicitly. TLB entries are flushed explicitly. TLB lockdown mechanism provided by processor can TLB lockdown mechanism provided by processor can be used to avoid TLB flushing and reloading be used to avoid TLB flushing and reloading Two lockdown TLB entries used for Two lockdown TLB entries used for Xen Xen pages pages

ARM926 provides 8 lockdown TLB entries ARM926 provides 8 lockdown TLB entries

Guest Domain Guest Domain Guest Domain Guest Domain Xen Xen (TLB (TLB lockdowned lockdowned) ) Guest Domain Guest Domain

0x00000000 0xFF000000 0xFFFFFFFF

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Back Back-

• end Driver

end Driver Front Front-

• end Driver

end Driver Native Driver Native Driver HID Event Router HID Event Router Ethernet Ethernet KeyPad KeyPad Sound Sound LCD LCD Touch Touch-

• Screen

Screen Flash Flash

Application Application

Xen Xen on ARM

• n ARM

i.MX21 i.MX21 Platform Platform

Communications Communications via virtual I/O via virtual I/O between domains between domains Route HID interrupts Route HID interrupts to the foreground to the foreground domain domain

Application Application

I/O Virtualization (1/2) I/O Virtualization (1/2)

Mixed Device Driver Architecture Mixed Device Driver Architecture

Split device drivers and coordinated native device drivers Split device drivers and coordinated native device drivers

UART UART HID Devices HID Devices Native HID Drivers Native HID Drivers (LCD, TS) (LCD, TS) Native HID Drivers Native HID Drivers (LCD, TS) (LCD, TS)

Dom 0 Dom 0 Dom U Dom U

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I/O Virtualization (2/2) I/O Virtualization (2/2)

Mixed device driver architecture for devices Mixed device driver architecture for devices shared among guest domains shared among guest domains

Consists of split device drivers and deterministically Consists of split device drivers and deterministically coordinated native device drivers coordinated native device drivers

Split device driver model Split device driver model Xen Xen-

• compliant device driver architecture

compliant device driver architecture

E.g.: Network device, storage device, keypad device E.g.: Network device, storage device, keypad device

Coordinated native device driver model Coordinated native device driver model Foreground domain gets exclusive access rights to Foreground domain gets exclusive access rights to coordinated native devices coordinated native devices

Coordinated native device drivers installed in each guest OS Coordinated native device drivers installed in each guest OS domain domain One button in keypad is reserved to change between domains. One button in keypad is reserved to change between domains. E.g.: Human Interaction Device (HID: LCD, touch screen) and E.g.: Human Interaction Device (HID: LCD, touch screen) and UART UART

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System Boot Procedure System Boot Procedure

Xen Xen and and dom dom 0 kernel images are loaded at 0 kernel images are loaded at predefined memory location. predefined memory location.

Load Kernel Image for Dom 0 Load Kernel Image for Dom 0 Load and Jump to Load and Jump to Xen Xen Image Image Initialize System Resources Initialize System Resources (Timer, UART, Memory, IRQ) (Timer, UART, Memory, IRQ) Create Dom 0 Create Dom 0 Bootloader Bootloader Blob or u Blob or u-

• boot

boot Xen Xen/ARM /ARM Execute Dom 0 Execute Dom 0 Dom 0 Dom 0 Xen Xen 0xC1C00000 0xC1C00000 0xC0008000 0xC0008000 I.MX21 I.MX21 Load Address Load Address Platform Platform Partition 0 Xen Partition 1 Kernel Image Partition 2 File System (JFFS2) NOR Flash Partition for Dom 0 Create / Load Guest Domains Create / Load Guest Domains Guest Operating System Guest Operating System Ex) Para Ex) Para-

• virtualized Linux

virtualized Linux Hardware Initialization Hardware Initialization System Boot Procedure System Boot Procedure

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Guest domains ( Guest domains (dom dom U) are created and destroyed by a U) are created and destroyed by a user level application, dom0_util. user level application, dom0_util.

Dom0_util supports only create and destroy functions. Dom0_util supports only create and destroy functions.

Dom U kernel uses NAND flash memory as storage. Dom U kernel uses NAND flash memory as storage.

VM Create / Destroy VM Create / Destroy

dom0_util Domain control driver

Control guest domain Request Xen to create and execute / destroy dom U kernel, where this driver loads the kernel image.

Xen Partition 0 Kernel Image Partition 1 File System (JFFS2) NAND Flash Partition for Dom 1 0xc3c00000 0xc3c00000 I.MX21 I.MX21 Load Address Load Address Platform Platform

Create and execute dom U / destroy dom U

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Agenda Agenda

Requirements for Beyond 3G Mobile Device Requirements for Beyond 3G Mobile Device Goal and Approach Goal and Approach Xen Xen on ARM

• n ARM

Xen Xen on ARM Architecture

• n ARM Architecture

System Virtualization System Virtualization System Boot Operation System Boot Operation

Security Security

Security Architecture and Its Components Security Architecture and Its Components Implementation: Status Implementation: Status

Conclusions and Future Work Conclusions and Future Work Appendix Appendix

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Security Architecture Security Architecture

Secure Secure App3 App3 Access Control Access Control Decision Maker Decision Maker Access Control Access Control Policy Conductor Policy Conductor Hooks Hooks AC Policy AC Policy Manager Manager

• 1. Hypercall
• 3. Decision

Decision Decision Cache Cache Secure SW Secure SW I nstaller I nstaller

OS OS

Secure Secure App1 App1 Secure Secure App2 App2

Hardware Layer Domain Secure Domain (Dom 0) Open Domain (Dom U)

Flash Memory Flash Memory

E EMK

MK(Access

(Access Control Policy) Control Policy)

Devices Devices

App4 App4 App1 App1 App3 App3 App2 App2 App5 App5 Access Access Control Control

SoC SoC Secure ROM Secure ROM

Master Key (MK), Bootloader

CPU CPU

Secure Xen

Domain Domain I ntegrity Manager I ntegrity Manager Front Front-

• end

end device drivers device drivers

OS OS

Back Back-

• end

end device drivers device drivers

• 2. Access control query

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Secure Boot Secure Boot

SoC SoC Secure ROM Secure ROM

Master Key (MK), Master Key (MK), Bootloader Bootloader

Root of Trust Root of Trust Xen Xen Domains Domains

Integrity check of the Integrity check of the Xen Xen with with Cert Cert M

M

Integrity check of each Integrity check of each domain with domain with Cert Cert M

M

Flash Memory Flash Memory

E EMK

MK(Cert

(Cert M

M), signed

), signed Xen Xen, , signed domains signed domains … …

E EMK

MK: Encryption with the master key (MK)

: Encryption with the master key (MK) Cert Cert M

M: Manufacturer

: Manufacturer’ ’s public key certificate s public key certificate

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Secure Storage Secure Storage

SP1 SP2 OS Images Offset

Flash memory

Bootloader Bootloader I mage, Master Key (MK) I mage, Master Key (MK)

Secure ROM

Encrypted data DP1 DP2 DPn SP3 Secure partition Data Partition

Partitions for guest OS domains. Each OS is allowed to access it Partitions for guest OS domains. Each OS is allowed to access its own partition. s own partition. DP DPn

n

A secure partition for cryptographic keys which are used by secu A secure partition for cryptographic keys which are used by secure domain. re domain.

E EMK

MK(Cryptographic

(Cryptographic keys) keys)

SP SP3

3

A secure partition for access control policies. A secure partition for access control policies.

E EMK

MK(Access

(Access Control Policies) Control Policies)

SP SP2

2

A secure partition for A secure partition for Xen Xen image and data for integrity measurement during a image and data for integrity measurement during a system boot. system boot.

E EMK

MK(Xen

(Xen Image||Sig Image||SigM

M(H(Xen

(H(Xen Image))||Sig Image))||SigM

M(H(Secure

(H(Secure Domain Domain Image))||Sig Image))||SigM

M(H(Normal

(H(Normal Domain Domain Image))|| Image))||Cert CertM

M)

)

SP SP1

1

Manufacturer Manufacturer’ ’s public key certificate. It is used for integrity measurement o s public key certificate. It is used for integrity measurement of f Xen Xen or

• r

kernel images. kernel images. Cert CertM

M

Master key. Each mobile device has a unique MK to encrypt data s Master key. Each mobile device has a unique MK to encrypt data stored in secure tored in secure partitions ( partitions (SPs SPs). ). MK MK Descriptions Descriptions Symbols Symbols

SP1 SP2 OS Images DP1 DP2 OS image partition SP1 SP2 OS Images DP1 DP2

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Access Control (1/2) Access Control (1/2)

Flexible architecture based on Flask Flexible architecture based on Flask Objects for access control Objects for access control

Physical resources Physical resources

Memory, CPU, IO space, IRQ, DMA Memory, CPU, IO space, IRQ, DMA

Virtual resources Virtual resources

Event channel, grant table Event channel, grant table

Domain management Domain management

Creation and destroy of guest domains Creation and destroy of guest domains

Multi Multi-

• layered access control not to degrade

layered access control not to degrade Xen Xen performance performance

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Access Control (2/2) Access Control (2/2)

Use case Use case

Resources which are used badly due to Resources which are used badly due to DoS DoS attacks are controlled by access control module attacks are controlled by access control module (ACM) using our proprietary policy (ACM) using our proprietary policy

Resources: CPU, memory, DMA, the number of Resources: CPU, memory, DMA, the number of event channel, battery event channel, battery E.g.: E.g.: ACM can control CPU time allocated to a guest ACM can control CPU time allocated to a guest domain in order to keep domain in order to keep malware malware on this domain

• n this domain

from using CPU excessively from using CPU excessively If battery stock is less than a threshold, ACM shuts If battery stock is less than a threshold, ACM shuts a guest domain down a guest domain down

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Implementation: Status (1/2) Implementation: Status (1/2)

Access control Access control

35 access control hooks in 35 access control hooks in hypercalls hypercalls used for used for access to physical resources or virtual resources, access to physical resources or virtual resources, and domain management and domain management Type Enforcement (TE) policy and proprietary Type Enforcement (TE) policy and proprietary policy to protect a mobile device from policy to protect a mobile device from DoS DoS attacks attacks Performance Performance

About 20 micro sec. per access control hook About 20 micro sec. per access control hook

Secure boot Secure boot

Integrity measurement of a Integrity measurement of a Xen Xen and two domains and two domains Performance Performance

About 75 ms for the integrity measurement (digital About 75 ms for the integrity measurement (digital signature verification) during a system boot signature verification) during a system boot

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Implementation: Status (2/2) Implementation: Status (2/2)

Secure storage Secure storage

Secure partitioning applied to NAND/NOR flash Secure partitioning applied to NAND/NOR flash memory memory Secure ROM simulated by using NOR flash memory Secure ROM simulated by using NOR flash memory

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Agenda Agenda

Requirements for Beyond 3G Mobile Devices Requirements for Beyond 3G Mobile Devices Goal and Approach Goal and Approach Xen Xen on ARM

• n ARM

Xen Xen on ARM Architecture

• n ARM Architecture

System Virtualization System Virtualization System Boot Operation System Boot Operation

Security Security

Security Architecture and Its Components Security Architecture and Its Components Implementation: Status Implementation: Status

Conclusions and Future Work Conclusions and Future Work Appendix Appendix

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Requires Requires

V Virtualized three CPU modes

irtualized three CPU modes

Modes: Modes: Xen Xen, kernel and user process , kernel and user process

Protection of virtual address spaces for Protection of virtual address spaces for Xen Xen, kernel and user process through , kernel and user process through domain access control domain access control

Mixed device driver architecture for shared Mixed device driver architecture for shared devices works well devices works well

Split device drivers and deterministically Split device drivers and deterministically coordinated native device drivers coordinated native device drivers

Conclusions (1/2) Conclusions (1/2) Xen Xen on ARM for Mobile Devices

• n ARM for Mobile Devices

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Requires Requires

Integrity measurement of core components Integrity measurement of core components

Multi Multi-

• layered

layered access control

access control

Access control at Access control at Xen Xen layer layer

Physical/virtual resources and domain management Physical/virtual resources and domain management are enforced by ACM at are enforced by ACM at Xen Xen

Access control at domain layer Access control at domain layer

In order not to degrade In order not to degrade Xen Xen performance, detailed performance, detailed access control of the resources in each domain is access control of the resources in each domain is individually enforced by ACM at each domain individually enforced by ACM at each domain

Conclusions (2/2) Conclusions (2/2) Xen Xen Security for Mobile Devices Security for Mobile Devices

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Future Work Future Work

Virtualization of DMA Virtualization of DMA Merging Merging Xenstore Xenstore Dynamic memory allocation to guest Dynamic memory allocation to guest domains domains Secure download protocol Secure download protocol Study on separation of a device driver Study on separation of a device driver domain from guest OS kernel domain from guest OS kernel Performance analysis and optimization Performance analysis and optimization

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Prototype Demo: Video Prototype Demo: Video

HW: a smart phone development platform HW: a smart phone development platform

CPU: ARM9, 266 MHz CPU: ARM9, 266 MHz System memory: 64 MB System memory: 64 MB HID: 3.5 inch LCD, touch screen, keypad HID: 3.5 inch LCD, touch screen, keypad Storage: NAND/NOR flash memory Storage: NAND/NOR flash memory Network: Ethernet Network: Ethernet

SW SW

VMM: secure VMM: secure Xen Xen on ARM

• n ARM

OS: OS: para para-

• virtualized ARM Linux 2.6.11

virtualized ARM Linux 2.6.11 GUI: GUI: Qtopia Qtopia

Contents: booting secure Contents: booting secure Xen Xen and and dom dom 0 (Linux), 0 (Linux), creating/destroying creating/destroying dom dom U (Linux), and etc. U (Linux), and etc.

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References References

[COK06] G. Coker, [COK06] G. Coker, “ “Xen Xen Security Modules (XSM), Security Modules (XSM),” ” Xen Xen Summit, Summit, 2006. 2006.

[GOS06] A. [GOS06] A. Gostev Gostev, , “ “Mobile Mobile Malware Malware Evolution: An Overview, Part Evolution: An Overview, Part

1, 1,” ” 2006. 2006. http://www.viruslist.com/en/analysis?pubid=200119916 http://www.viruslist.com/en/analysis?pubid=200119916 [KAW05] D. Kawamoto, [KAW05] D. Kawamoto, “ “2006: Year of the mobile 2006: Year of the mobile malware malware, ,” ” 2005. 2005. http://news.com.com/2006+Year+of+the+mobile+malware/2100 http://news.com.com/2006+Year+of+the+mobile+malware/2100-

• 7349_3

7349_3-

• 6001651.html

6001651.html [SAI05] R. [SAI05] R. Sailer Sailer, E. Valdez, T. Jaeger, R. Perez, L. van , E. Valdez, T. Jaeger, R. Perez, L. van Doorn Doorn, J. , J.

• L. Griffin, and S. Berger.
• L. Griffin, and S. Berger. “

“sHype:A sHype:A secure secure hypervisor hypervisor approach approach to trusted virtualized systems, to trusted virtualized systems,” ” IBM Research Report, 2005. IBM Research Report, 2005. [ARM01] Andres [ARM01] Andres N.Sloss N.Sloss, Dominic , Dominic Symes Symes, , C.Wright C.Wright. . “ “ARM ARM System Developer System Developer’ ’s Guide s Guide” ”, Morgan Kaufmann, 2004 , Morgan Kaufmann, 2004 [KEV01] Kevin Lawton, [KEV01] Kevin Lawton, “ “Running multiple operating systems Running multiple operating systems concurrently on an IA32 PC using virtualization techniques concurrently on an IA32 PC using virtualization techniques” ”. . 2000. 2000.

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Agenda Agenda

Requirements for Beyond 3G Mobile Device Requirements for Beyond 3G Mobile Device Goal and Approach Goal and Approach Xen Xen on ARM

• n ARM

Xen Xen on ARM Architecture

• n ARM Architecture

System Virtualization System Virtualization System Boot Operation System Boot Operation

Security Security

Security Architecture and Its Components Security Architecture and Its Components Implementation: Status Implementation: Status

Conclusions and Future Work Conclusions and Future Work Appendix Appendix

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Comparison: Comparison: Xen Xen

Lightweight version of XM Lightweight version of XM XM XM Booting guest domain U Booting guest domain U NAND, NOR flash NAND, NOR flash IDE, SCSI HDD IDE, SCSI HDD Virtual Block Device Virtual Block Device Support Support Deterministically coordinated Deterministically coordinated HID Device Driver HID Device Driver Xenconsole Xenconsole daemon daemon and and xenconsole xenconsole client client Console I/O Console I/O Static Static Dynamic Dynamic Memory allocation to Memory allocation to domain domain Modified Modified Xenbus Xenbus* / * / Proprietary Proprietary ( (Xenstore Xenstore to be implemented) to be implemented) Xenbus Xenbus / / Xenstore Xenstore Virtual Device Interface / Virtual Device Interface / Device Configuration Device Configuration Xen Xen/ARM /ARM Xen/x86 Xen/x86 Feature Feature

* Modified * Modified Xenbus Xenbus to support virtual I/O setup without to support virtual I/O setup without xenstore xenstore Based on current status Based on current status

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Comparison: CPU Comparison: CPU

Indirect execution Indirect execution through VMM through VMM Direct execution Direct execution Software Interrupt Software Interrupt Handling Handling 18 [ARM01] 18 [ARM01] (in case of ARM v5) (in case of ARM v5)

• Approx. 57 [KEV01]
• Approx. 57 [KEV01]

# of sensitive # of sensitive instructions instructions VIVT VIVT – – Cache Alias Cache Alias PIPT PIPT – – No cache alias No cache alias Cache Model Cache Model 2 2 4 4 # of Privilege levels # of Privilege levels ARM v4/v5 ARM v4/v5 x86 x86 Feature Feature

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Comparison: Access Control Comparison: Access Control

Xen Xen on ARM specific

• n ARM specific

hooks hooks Etc Etc Enforced by ACM at Enforced by ACM at each domain (for each domain (for performance reason) performance reason) Enforced by ACM at Enforced by ACM at VMM VMM Enforced by ACM at Enforced by ACM at VMM VMM Access control to Access control to

• bjects in each guest
• bjects in each guest

domain domain Memory, battery, Memory, battery, DMA, and event DMA, and event channels are channels are controlled by ACM controlled by ACM N/A N/A N/A N/A Protection against Protection against mobile mobile malware malware-

• based

based DoS DoS attacks attacks Physical/virtual Physical/virtual resources and resources and domain management domain management Physical/virtual Physical/virtual resources and resources and domain management domain management Virtual resources and Virtual resources and domain management domain management Objects of access Objects of access control control Flexible based on Flexible based on Flask (TE and Flask (TE and proprietary policy) proprietary policy) Flexible based on Flexible based on Flask (TE, Chinese Flask (TE, Chinese Wall, RBAC, MLS, and Wall, RBAC, MLS, and MCS) MCS) Flexible based on Flexible based on Flask (TE and Flask (TE and Chinese Wall) Chinese Wall) Access Control Access Control Policies Policies Our ACM Our ACM XSM [COK06] XSM [COK06] sHype sHype [SAI05] [SAI05]

sHype sHype, XSM, and Our ACM , XSM, and Our ACM

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Performance (1/2) Performance (1/2)

Bandwidth Test ( Bandwidth Test (LMBench LMBench): Snapshot ): Snapshot

200 400 600 800 1000 1200 P i p e A F _ U N I X s

• c

k e t s t r e a m M e m

• r

y W r i t e F i l e W r i t e F i l e C

• p

y B l

• c

k Z e r

• F

i l l B l

• c

k C

• p

y (MB/sec) Native Linux Para-virtualized Linux

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SW Laboratories, CTO, Samsung Electronics SW Laboratories, CTO, Samsung Electronics

Performance (2/2) Performance (2/2)

Latency Test ( Latency Test (LMBench LMBench): Snapshot ): Snapshot

50 100 150 200 250 300 350 400 F i l e l

• c

k / u n l

• c

k P i p e S e m a p h

• r

e A F _ U N I X s

• c

k e t s t r e a m S i g n a l ( i n s t a l l ) S i g n a l ( c a t c h ) S y s t e m C a l l ( n u l l ) S y s t e m C a l l ( r e a d ) S y s t e m C a l l ( w r i t e ) P r

• c

e s s c r e a t i

• n

( p r

• c

e d . . . microsecond Native Linux Para-virtualized Linux

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Xen Xen Tools Tools

Xen Xen Tools Tools

Python packages are too big for small flash memory. Python packages are too big for small flash memory. Smaller size by removing unused Python modules. Smaller size by removing unused Python modules.

40 40 280 280 # of modules # of modules 5.7MB 5.7MB 40MB 40MB T Total size

• tal size

Embedded Python Embedded Python Full Python Full Python

Python version : 2.4.3 Python version : 2.4.3

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I/O Virtualization: I/O Virtualization: Xenbus Xenbus

Modified Modified Xenbus Xenbus

Modified to Modified to support virtual I/O setup without

support virtual I/O setup without xenstore xenstore. . Xenstore Xenstore porting is in progress porting is in progress.

.

All configuration data is maintained in shared All configuration data is maintained in shared configuration page. configuration page.

E.g. : E.g. : Event Channel No. Event Channel No. Grant Table Ref. No. Grant Table Ref. No.

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I/O Virtualization: example I/O Virtualization: example

Application Application

Xen Xen on ARM

• n ARM

NOR Flash Chip NOR Flash Chip

Application Application

Back Back-

• end MTD Driver

end MTD Driver Front Front-

• end MTD Driver

end MTD Driver Modified Modified Xenbus Xenbus Virtual I/O Virtual I/O help to setup JFFS2 JFFS2 JFFS2 JFFS2 Native MTD Native MTD NOR Flash NOR Flash Chip Driver Chip Driver

Virtual Memory Technology Device (MTD) Driver Virtual Memory Technology Device (MTD) Driver

To share flash memory between guest domains To share flash memory between guest domains

NAND Flash Chip NAND Flash Chip NAND Flash NAND Flash Chip Driver Chip Driver

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Xen Xen on ARM

• n ARM

I/O Virtualization: example I/O Virtualization: example

Application Application Application Application Native Driver Native Driver Bridge Bridge Modified Modified Xenbus Xenbus Virtual I/O Virtual I/O help to setup help to setup

Virtual Network Driver Virtual Network Driver

Use synchronous I/O buffer instead of asynchronous Use synchronous I/O buffer instead of asynchronous I/O ring. I/O ring. Transmit and receive data via shared pages Transmit and receive data via shared pages

Ethernet Device Ethernet Device Back Back-

• end

end Front Front-

• end

end

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Current Source Code Status (1/2) Current Source Code Status (1/2)

Xen Xen/ARM (3.0.2) /ARM (3.0.2)

720 720 security/ security/secure_storage secure_storage 1500 1500 security/ security/secure_boot secure_boot 793 793 security/crypto security/crypto 4030 4030 Include/asm Include/asm-

• arm/arch

arm/arch-

• omap
• map

Include/asm Include/asm-

• arm/arch

arm/arch-

• imx

imx include/ include/asm asm-

• arm

arm arch/arm/lib arch/arm/lib arch/arm/arch arch/arm/arch-

• omap
• map

arch/arm/arch arch/arm/arch-

• imx

imx arch/arm/ arch/arm/xen xen security/ security/access_control access_control Directory Directory 2110 2110 4953 4953 2695 2695 1127 1127 1031 1031 7455 7455 2500 2500 LOC LOC

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Current Source Code Status (2/2) Current Source Code Status (2/2)

Include/ Include/asm asm-

• arm

arm arch/arm/mach arch/arm/mach-

• imx

imx a arch/arm/mm rch/arm/mm a arch/arm/kernel rch/arm/kernel Directory Directory 646 646 1008 1008 1730 1730 1134 1134 LOC LOC

Para Para-

• virtualized Linux Kernel (2.6.11)

virtualized Linux Kernel (2.6.11)