Introduction to Qubes OS(en)

bhyvecon Tokyo 2014 発表資料 http://peatix.com/event/30515 #bhyvecon

Transcript

1. Introduction to Qubes OS bhyvecon Tokyo 2014 @ntddk
2. Self-introduction • Yuma Kurogome(@ntddk) • Takeda Lab @ KEIO Univ. • Researching about security in low-layer • Participant of Security Camp '11, '13 • CTF player @ EpsilonDelta
3. What is Qubes OS?
4. What is Qubes OS? • Secure VM developing by Invisible Things Lab • Security by Isolation • Open Source(GPL v2) • Based on Xen – So today I don't speak about bhyve – Wish I could supply some inspiration for you!
5. Invisible Things Lab
6. Invisible Things Lab • Founded by Joanna Rutkowska in 2007 – Who forced Citrix to publish souces of XenClient – Published Blue Pill[SyScan'06] when she were in COSEINC • Blue Pill – VT based rootkit(hypervisor) • Previous rootkit were on Ring 0 – Hooking System Call – Altering Kernel Structure – So we can detect it
7. Invisible Things Lab • VT based rootkit were on Ring -1 – So we can hardly detect it *after infection* – For now, VT based rootkit is not serious threat
8. Invisible Things Lab • They had been researched about – rootkit – SMM(System Management Mode) – Intel TXT(Trusted Execution Technology) • Now they are developing Secure VM focused on mechanism of Xen
9. Well... What's the difference between Xen and KVM?
10. Review: difference betwen Xen and KVM • Virtualization methods • Intrrupt • Memory mapping
11. Review: difference betwen Xen and KVM • Xen – Para-Virtualization – Full-Virtualization by Intel VT Hardware Xen Para-Virtualized OS Priviledged Domain Para-Virtualized OS Full-Virtualized OS
12. Review: difference betwen Xen and KVM • KVM – Full-Virtualization – Para-Virtualization by virtio Hardware Linux + KVM Full-Virtualized OS Full-Virtualized OS Full-Virtualized OS
13. Review: difference betwen Xen and KVM • Virtualization methods – Para-Virtualization • Modify OS for virtualized environment • No need of full hardware emulation – Full-Virtualization • No need of modifying OS • Inturrupt – Xen uses event channnel – KVM uses MSI(-X)
14. Review: difference betwen Xen and KVM • Memory mapping – KVM Gest-Physical memory space is part of host-virtual memory space of QEMU – Xen Mapping Gest-Physical memory space On demand • Both use HW-assisted virtualization – Intel VT, AMD-V
15. Well... What is Intel VT?
16. Review: Intel VT • Handling sensitive instructions – How to emulate it? – Tired to rewriting instrctuions by hand
17. Review: Intel VT(VMX) 1.Load some settings to VMCS 2.Set CPU to VMCS 3.VMLAUNCH → VMEntry, Enter VMX non- root mode(Guest mode) 4.Execute guest environment 5.Cause of trap → VMExit, Enter VMX root mode 6.Check VMExit reasons, emulation 7.VMRESUME → VMEntry, Enter VMX non- root mode → 4
18. Review: Intel VT(VMX) • What is VMCS? – Virtual Machine Control Structure • Program Counter • Register • VM • What to trap
19. Review: Intel VT(EPT) • Simplifying Paging – Tired to twice translation – Shadow Page Table • EPT – Extended Page Table – Address translation by HW – Reduction of Overhead
20. Review: Intel VT(EPT) • We can easily make VMM using VT! → KVM • Xen... – Need of HyperCall – Full-Virtualization by VT
21. Xen Virtualization Hardware Xen VM(Dom0) VM(DomU 1) VM(DomU 2) Driver Backend Driver Frontend Driver Frontend Driver • Xen has a Dom0(host) and some DomU(guest)
22. Xen Virtualization • Xen hypervisor execute Dom0 before DomU • Dom0 manages other DomU – Only Privilege Domain is allowed to access all HW – DomU ask Dom0 to HW access via Backend/Frontend Driver • Qubes OS apply this architecture to security
23. Concept of Qubes OS
24. Desktop Environment • Qubes OS want to provide strong security to desktop environment Spreadsheet with your company's data Web Browser Mail Client
25. Desktop Environment • People use different applications there Spreadsheet with your company's data Web Browser Mail Client Game
26. Desktop Environment • If this game was malware? Spreadsheet with your company's data Web Browser Mail Client Game Information leakage
27. Desktop Environment • If the Web Browser has vulnerability? Spreadsheet with your company's data Web Browser Mail Client Information leakage
28. It's Painful!
29. Two Approaches • Security by Correctness • Security by Isolation
30. Security by Correctness • Code Auditing • Developers education – Microsoft Security Development Lifecycle • Testing – Fuzzing • “Safe”Programming Language • It doesn't work in practice!
31. Security by Isolation • We want the OS to provide isolation between various apps • If some of them get compromised... Spreadsheet with your company's data Web Browser Mail Client Game Cutoff
32. Security by Isolation • We want to even “decompose”some apps... • e.g. Web Browser – Internal Systems – Shopping – News – Googling
33. Security by Isolation • Isolation provided by OSes are not enogh? – Address space isolation – User accounts isolation – ACL – Kernel/User space separation – chroot – systrace – SELinux – Secure level of BSD • They don't work in practice!
34. Security by Isolation • Monolithic kernels are buggy! • Hundreds of 3rd-party drivers cannot be made secure! “One bug to rule them all!”
35. Then, Qubes OS
36. Virtualization for rescue!
37. Melits of virtualization • Bug(vuln) is proportional to LOC – [SOSP01],[ICCSA03] • Linux: ten of millions LOC! • Bare-metal hypervisor: 100k~300k LOC only!
38. Conceptual Diagram • App Domain • Strage Domain • Network Domain • Domain 0 Come true Isolation!!!
39. Dom0 • Provides secure environment and manager • Dom0 doesn't contain Network function and Storage function • Only 25k LOC!!!!!!!!
40. Strage Domain • Non-privileged VM • Only support Storage function
41. Network Domain • Non-privileged VM • Only support Network function
42. AppVM • Main Qubes building blocks(cubes) • Hosts user applications • We can create VM(Domain) depending on their Use – Work – Shopping – Personal • Domains are isolated each other → SECURE! • Created by Template VM(Read Only)
43. AppVM • Disposable VM – Only supports ONE application – If compromised, there are no informations • Lightweight – 400MB per VM • Centrally Updatable • Each app gets a label (VM name + color frame) that is applied by the Window Manager running in Dom0
44. AppVM “Work” VM “Shopping” VM “Work” VM Desktop ハイパーバイザによるIsolation
45. Screenshot 行 1 行 2 行 3 行 4 0 2 4 6 8 10 12 列 1 列 2 列 3 http://wiki.qubes-os.org/trac/attachment/wiki/QubesScreenshots/r2b2-kde-three-domains- at-work.png
46. GUI Virtualization Introducing Qubes OS qubes-intro-apr-2010.pdf
47. VM Protection • Research about VM Protections • Overshadow[ASPLO08] – Get context of Guest OS from VMM – Encrypt pages at memory access – Show process to not-encrypted memory – Need original loader • SP3[Vee08] – Process memory encyption from VMM – Set accsess control per page – Has both encrypted page and not-encrypted page → Reduction of Overhead
48. VM Protection • Qubes OS uses Intel VT-d and Intel TXT Protecting VM • DMA Protection – Direct Memory Access – R/W memory from HW – No need of CPU
49. DMA Virtualization by Intel VT-d 1.HW → DMA Request 2.DMA Remapping Engine refers to Device Assignment Structure 3.Get Address Translation Structure
50. DMA Virtualization by Intel VT-d • Prevents access from the address range other than the VM at address translation • At early boot sequense before VT-d initialized, Intel TXT protects VM
51. Intel TXT • Trust – All work as expected! – Identity and Measurement • Establish Trust by RTM(Root of Trust for Measurement) – Reliable engine makes a measurement of integrity – Root of Trust → Chain of Trust
52. Intel TXT • RTM – RTM cannot measures itself • Static RTM – RTM is firmware – Building Chain of Trust from booting • Dynamic RTM – RTM is GETSEC[SENTER] instruction – Building Chain of Trust from executing instruction – SENTER enable DMA protection so we can protect VM! “Kill two birds with one stone”
53. Intel TXT • Intel TXT uses both SRTM and DRTM • BIOS(chip) → (SRTM) → bootloader →　 (SRTM) → os → (DRTM) → hypervisor (thx @yuzuhara)
54. Strage Introducing Qubes OS qubes-intro-apr-2010.pdf
55. Cross-VM • Qubes OS has some Cross-VM functions – Clipboard sharing – File transfer via virtual disk • Cross VM vulnerability is easily targeted • Insert rootkit at LiveMigration[BlackHat DC08] • Cross VM Side Channel Attack[CCS12] – Estimate the access from another VM from response when malicious VM access physical cache continuously – Might steal the key
56. Filesystem Introducing Qubes OS qubes-intro-apr-2010.pdf
57. Summaly • Domain oriented VM • Creates Xen's VM per use • Seamless operation by GUI virtualization • DMA protection by Intel VT-d • Strage protection by Intel TXT • Filesystem protection by VM-specific key
58. See qubes-os.org
59. Q&A?
60. Thank you!