Why open source firmware is important Jessie Frazelle - @jessfraz - - PowerPoint PPT Presentation

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Why open source firmware is important Jessie Frazelle - @jessfraz - - PowerPoint PPT Presentation

Oct 30, 2022 155 likes •786 views

Why open source firmware is important Jessie Frazelle - @jessfraz Points of View 1. Security 2. Usability 3. Visibility First Point of View: Security... Software Software Operating System Kernel Firmware Hardware Software Software

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Why open source firmware is important

Jessie Frazelle - @jessfraz

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Points of View

  • 1. Security
  • 2. Usability
  • 3. Visibility
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First Point of View: Security...

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Hardware Firmware Operating System Kernel Software Software

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Hardware Software Software Software Software

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Hardware Software Software Software Software

💪 💪 💪 💪 💪

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Ring -3: Management Engine Ring -2: SMM, UEFI kernel Ring -1: Hypervisor Ring 0: Kernel Ring 3: User space

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Ring -3: Management Engine Ring -2: SMM, UEFI kernel The code we don’t know about...

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Ring -2: SMM, UEFI kernel System Management Mode

  • Originally used for power management
  • System hardware control
  • Proprietary designed code
  • Place where vendors add new features
  • Handle system events like memory or

chipset errors

  • ½ kernel
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Ring -2: SMM, UEFI kernel UEFI Kernel

  • Extremely complex
  • Millions of lines of code
  • UEFI applications are active after boot
  • Security from obscurity
  • A bajillion features, extremely complex
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Ring -3: Management Engine Management Engine

  • Networking management
  • KVM management
  • Intel proprietary features
  • Can reimage your device even if it’s

powered off

  • Can turn on node invisibly
  • Minux
  • SO MUCH MORE
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That’s just one example of a bad attack but if you google you can easily find

  • thers...
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This is bad.

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It gets even worse.

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Intel Boot Guard

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Ring -3: Management Engine Ring -2: SMM, UEFI kernel Adds up to: 2½ other kernels/OSes…

  • They each have their own networking

stacks, web servers (wtf)

  • The code can modify itself and persist

across power cycles and reinstalls

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Ring -3: Management Engine Ring -2: SMM, UEFI kernel Adds up to: 2½ other kernels/OSes…

  • They are all incredibly and

unnecessarily complex

  • THEY ALL HAVE EXPLOITS!
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Second Point of View: Usability...

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The results

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29.2%

Mentioned Firmware as a Pain Point

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So at what scale is firmware a pain?

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My hypothesis...

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Once you need to deal with the firmware it becomes a pain...

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Third Point of View: Visibility...

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Conway’s Law

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From the perspective of hardware engineers...

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“You’d be crazy to think hardware was ever intended to be used for isolating multiple users safely..”

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Spectre and Meltdown proved this to be true as well.

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From the perspective of firmware and kernel engineers…

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They want vendors to make their firmware do less, or give up the control to them.

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Vendors can rarely debug firmware issues…

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Oversights and lack of communication leads to...

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How did no one think about the BMC when building softlayer?

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I’ve personally seen these miscommunications happen in the container ecosystem as well...

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Miscommunications at various layers of the stack lead to bugs in the intersecting layers, based off incorrect assumptions.

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Hardware Software Software Software Software

💪 💪 💪 💪 💪

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How do we fix these things?

  • 1. Security
  • 2. Usability
  • 3. Visibility
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Open Source Firmware

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NERF: Non-Extensible Reduced Firmware

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NERF Goals

  • Make firmware less capable of doing harm
  • Make its actions more visible
  • Remove all runtime components
  • With ME we can’t remove all but we

can take away the web server and IP stack

  • Remove UEFI IP stack and other drivers
  • Remove ME/UEFI self-reflash capability
  • Let linux manage flash updates
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Ring -3: Management Engine Ring -2: SMM, UEFI kernel Ring -1: Hypervisor Ring 0: Kernel Ring 3: User space

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Ring -3: Management Engine Ring -2: SMM, UEFI kernel Ring -1: Hypervisor Ring 0: Kernel Ring 3: User space

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Ring -2:

SMM disabled Reduced UEFI ROM Linux kernel and Minimal userland

Ring -3: Minimized Management Engine Ring -1: Hypervisor

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u-boot or coreboot

silicon and DRAM initialization

linuxboot

device drivers, network stack, multi-user/tasking environment

u-root

userspace tools and bootloader, initramfs

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Why linux?

  • Single kernel works for several boards
  • Already quite vetted and has a lot of

eyes on it since it is used quite extensively

  • Single, open source kernel versus the 2½
  • ther kernels that were all different

and most closed off

  • Improves boot reliability by replacing

lightly-tested firmware drivers with hardened Linux drivers.

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Other wins

  • Firmware devs can build in tools they

already know

  • When they need to write logic for

signature verification, disk decryption, etc it’s in a language that is modern, easily auditable, maintainable, and readable

  • Memory safety wins as well since the

language can be higher level

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Makes boot time 20x faster.

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Through open source, visibility, minimalism, and open communication we can push computing to a better, more secure place from the hardware up.

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We can’t keep building

  • n top of 💪. We

really need to care about the base we build on.

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Huge thanks to the firmware community for all their work

  • n this!
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Ron Minnich Trammel Hudson Chris Koch Rick Altherr Zaolin

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Thanks for having me!