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Software update for IoT: the current state of play

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Many embedded Linux projects have a requirement to update the software on devices in the field. Recent security flaws in basic components such as OpenSSL and bash, combined with the interconnectedness of all things, have highlighted the problem and made it an absolute necessity

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Software update for IoT: the current state of play

  1. 1. Software update for IoT the current state of play Chris Simmonds OpenIoT Summit 2016 Software update for IoT 1 Copyright © 2011-2016, 2net Ltd
  2. 2. License These slides are available under a Creative Commons Attribution-ShareAlike 3.0 license. You can read the full text of the license here http://creativecommons.org/licenses/by-sa/3.0/legalcode You are free to • copy, distribute, display, and perform the work • make derivative works • make commercial use of the work Under the following conditions • Attribution: you must give the original author credit • Share Alike: if you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one (i.e. include this page exactly as it is) • For any reuse or distribution, you must make clear to others the license terms of this work Software update for IoT 2 Copyright © 2011-2016, 2net Ltd
  3. 3. About Chris Simmonds • Consultant and trainer • Author of Mastering Embedded Linux Programming • Working with embedded Linux since 1999 • Android since 2009 • Speaker at many conferences and workshops "Looking after the Inner Penguin" blog at http://2net.co.uk/ https://uk.linkedin.com/in/chrisdsimmonds/ https://google.com/+chrissimmonds Software update for IoT 3 Copyright © 2011-2016, 2net Ltd
  4. 4. Overview • Software update 101 • Update clients • OTA update • OTA implementations Software update for IoT 4 Copyright © 2011-2016, 2net Ltd
  5. 5. What could possibly go wrong? • Mirai: a recent > 600 Gbps DDoS attack • Very simple: looks for open Telnet ports and logs on using default, well-known, name and password • Prime target: Dahua IP CCTV cameras Details on PenTestPartners: https://www.pentestpartners.com/blog/ optimising-mirai-a-better-iot-ddos-botnet Software update for IoT 5 Copyright © 2011-2016, 2net Ltd
  6. 6. Problems Problem 1 • Embedded software is non-trivial (=> has bugs!) • Devices are often connected to the Internet • Allowing intruders to exploit the bugs remotely Problem 2 • We would like to deploy new features, improve performance, etc. Conclusion • We need a software update mechanism Software update for IoT 6 Copyright © 2011-2016, 2net Ltd
  7. 7. Requirements for SW update • Secure, to prevent the device from being hijacked • Robust, so that an update does not render the device unusable • Atomic, meaning that an update must be installed completely or not at all • Fail-safe, so that there is a fall-back mode if all else fails • Preserve persistent state Software update for IoT 7 Copyright © 2011-2016, 2net Ltd
  8. 8. What to update? Frequency Ease of update Bootloader Kernel Root file system System applications Software update for IoT 8 Copyright © 2011-2016, 2net Ltd
  9. 9. Update granularity • File: • not an option: hard to achieve atomicity over a group of file updates • Package: • apt-get update works fine for servers but not for devices • Container: • neat idea, so long as you have containerised applications • Image: • the most common option: fairy easy to implement and verify Software update for IoT 9 Copyright © 2011-2016, 2net Ltd
  10. 10. Device update != server update • Server • Secure environment, no power outage, no network outage • If update fails, human intervention is possible • Device: • Intermittent power and network mean update quite likely to be interrupted • Failed update may be difficult (and expensive) to resolve Software update for IoT 10 Copyright © 2011-2016, 2net Ltd
  11. 11. Options for image update Symmetric A/B (Android after Nougat) Bootloader User data Boot flag OS Copy 1 OS Copy 2 Bootloader Main OS Recovery OS User data Boot flag Asymmetric normal/recovery (Android before Nougat) Software update for IoT 11 Copyright © 2011-2016, 2net Ltd
  12. 12. Statelessness • Image update of a filesystem implies no state is stored in that filesystem • See my talk about read-only rootfs http://www.slideshare.net/chrissimmonds/ readonly-rootfs-theory-and-practice Software update for IoT 12 Copyright © 2011-2016, 2net Ltd
  13. 13. Update agent • Update agent is the code on the device that manages the update • Tasks • Receive update from local storage (e.g. USB) or from remote server • Apply the update • Toggle boot flag Software update for IoT 13 Copyright © 2011-2016, 2net Ltd
  14. 14. swupdate • Image-based update client • License: GPLv2 • Code https://github.com/sbabic/swupdate • Documentation http://sbabic.github.io/swupdate/index.html Software update for IoT 14 Copyright © 2011-2016, 2net Ltd
  15. 15. swupdate features • Symmetric and asymmetric update • Bootloader support: U-Boot • Volume formats: MTD, UBI, MBR and UEFI partitions • Yocto Project layer: meta-swupdate • Remote/streaming using curl (http/https/ssh/ftp) • integrated REST client connector to hawkBit • Signed images Software update for IoT 15 Copyright © 2011-2016, 2net Ltd
  16. 16. RAUC - Robust Auto-Update Controller • Image-based update client • License: LGPLv2.1 • Source Code: https://github.com/jluebbe/rauc • Documentation: https://rauc.readthedocs.org/ Software update for IoT 16 Copyright © 2011-2016, 2net Ltd
  17. 17. RAUC features • Symmetric and asymmetric update • Bootloader support: grub, barebox • Volume formats: MTD, UBI, MBR and UEFI partitions • Build systems: Yocto Project (meta-ptx), PTXDist • Remote/streaming using curl (http/https/ssh/ftp) • Cryptographic verification using OpenSSL (signatures based on x.509 certificates) Software update for IoT 17 Copyright © 2011-2016, 2net Ltd
  18. 18. OTA update • Solutions so far are mostly suitable for • Local update (man with a USB thumb drive) • User initiated/attended remote update • Local or attended remote update does not scale • Hence, OTA (Over The Air) update • Updates pushed from central server • Update is automatic (or semi-automatic as with Android/IoS) Software update for IoT 18 Copyright © 2011-2016, 2net Ltd
  19. 19. OTA update components Device software build system Firmware images Sign with authentication key Update server Device Update agent Software update for IoT 19 Copyright © 2011-2016, 2net Ltd
  20. 20. Complexities of OTA update • Authentication (is this update legit?) • Security (am I receiving what you are sending?) • Roll-back (if update fails to boot, switch to previous version) • Scale (roll out to large populations) • Monitoring (keeping track of status of the population of devices) Software update for IoT 20 Copyright © 2011-2016, 2net Ltd
  21. 21. Roll-back • Boot limit count • Feature of bootloader (e.g U-Boot) • Increment count in bootloader • Reset after successful boot • If reboot with count > 0, bootloader knows boot failed and loads alternate rootfs • Hardware watchdog • If hang in early boot, watchdog times out and resets CPU • Bootloader checks reset reason • If watchdog, loads alternate rootfs Software update for IoT 21 Copyright © 2011-2016, 2net Ltd
  22. 22. Mender.io • OTA update server and client • Full system image update • Licenses: Server and Client: Apache 2 • Code (client): https://github.com/mendersoftware/mender • Documentation: https://docs.mender.io Software update for IoT 22 Copyright © 2011-2016, 2net Ltd
  23. 23. Mender.io features • Symmetric A/B image update client • Bootloader support: U-Boot • Volume formats: MBR and UEFI partitions • Update commit and roll-back • Build system: Yocto Project (meta-mender) • Remote features: deployment server, build artifact management, device management console Software update for IoT 23 Copyright © 2011-2016, 2net Ltd
  24. 24. Resin.io • OTA update server and client • Container (Docker) based updates • Licenses: Client: Apache2; Server: proprietary • Code (client): https://github.com/resin-os/meta-resin • Documentation: https://docs.resin.io/introduction Software update for IoT 24 Copyright © 2011-2016, 2net Ltd
  25. 25. resin.io features • Symetric A/B rootfs for core OS ("Resinhup") • Applications packaged into Docker containers • Build integration: Yocto Project (meta-resin) • Docker images can be preloaded into YP build • Remote features: deployment server, integration with git Software update for IoT 25 Copyright © 2011-2016, 2net Ltd
  26. 26. Brillo • Brillo is cut-down Android for IoT • License: Apache 2.0 • Android OTA update client • Symmetric and asymmetric image update • Licenses: Client: Apache2; Server: proprietary • Code (client): https://android.googlesource.com • Documentation: https://developers.google.com/brillo Software update for IoT 26 Copyright © 2011-2016, 2net Ltd
  27. 27. Conclusion • Software update is a hot topic • Open source solutions described in this presentation: • Stand-alone update clients • swupdaed • RAUC • End-to-end solutions • mender.io • resin.io This and other topics associated with building robust embedded systems are coverred in my training courses http://www.2net.co.uk/training.html Software update for IoT 27 Copyright © 2011-2016, 2net Ltd

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