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They are good enough to have their own Cellebrite column. If they complain about something, you should probably listen.
GrapheneOS says Pixel 11 has MTE support after all
81–90 of 175 posts
Re: GrapheneOS says Pixel 11 has MTE support after all
#82Earlier quoted context omitted.
To expand a bit: 16-byte chunks of memory can be associated with a four bit tag. Then you steal four unused high bits from your pointers to store a tag value. When memory has a tag, a pointer used to access it must have the matching tag in its high bits. Your malloc implementation can then assign a different tag to adjacent allocations and any overflow into an adjacent allocation will have a mismatched tag and will t…
4 bits per 16 bytes is ~ 1/4 the cost of ECC, which is possible to implement with just an extra cycle or two of latency in the memory controller. MTE seems similarly lightweight. Costs some transistors and a percent of a percent of power budget, but much like ECC it seems a fair bargain.
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Re: GrapheneOS says Pixel 11 has MTE support after all
#83Phones typically have 2 operating systems: one to handle telephonic functions like managing tower connections and separate operating system for user applications. The security implication here is that the telephonic operating system has access to the same system resources as the application operating system at the same time, right? The problem is your data is always available in plaintext to the telephonic OS because…
> The security implication here is that the telephonic operating system has access to the same system resources as the application operating system at the same time, right? It shouldn't. As per https://grapheneos.org/faq#baseband-isolation : > The baseband is isolated on all of the officially supported devices. Memory access is partitioned by the IOMMU and limited to internal memory and memory shared by the driver im…
IOMMU
The way it should have been all along.
Re: GrapheneOS says Pixel 11 has MTE support after all
#84Earlier quoted context omitted.
So other projects are not supposed to critize Google? Graphene's focus is on security and they complain about lack of security in your products. Seems valid to me. Also security and using non-Google OS are not niche usecases. I'm not sure how you are working on Android, the most popular OS while claiming security is a niche usecase. In fact, I have less confidence in security of your work.
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Re: GrapheneOS says Pixel 11 has MTE support after all
#85Earlier quoted context omitted.
MTE is essentially hardware-accelerated AddressSanitiser[1]. [1]: https://clang.llvm.org/docs/AddressSanitizer.html
To expand a bit: 16-byte chunks of memory can be associated with a four bit tag. Then you steal four unused high bits from your pointers to store a tag value. When memory has a tag, a pointer used to access it must have the matching tag in its high bits. Your malloc implementation can then assign a different tag to adjacent allocations and any overflow into an adjacent allocation will have a mismatched tag and will t…
What does the malloc or hardware do if for some reason your program needs to access memory addresses that overlap your tag bytes ?
I know that it's a really improbable scenario and the OS would also just refuse you allocations at some point, but what would the malloc implementation and the MTE do in such a case ? Fail the allocation ? trap when reading the pointer since it would point to the "wrong place" ?
Re: GrapheneOS says Pixel 11 has MTE support after all
#86[flagged]
... and my opinion becomes more positive with each rant. We'll have to agree to disagree. The only reason I buy Pixels for myself and my family members is because of GrapheneOS, otherwise it would be used out of date hardware for LineageOS or some kind of Linux phone. I am thankful that they are attempting to diversify with Motorola, being entirely Pixel dependent has been a project vulnerability; anytime Google decided to lock down the boot loader, it would have been curtains for the project.
Re: GrapheneOS says Pixel 11 has MTE support after all
#87Earlier quoted context omitted.
Thankfully the project doesn't care about your personal attitude. That "niche use case" literally saves lives in countries where saying the wrong thing can put you to death. Since when is calling something out a rant?
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In a world where economics makes security hardly a secondary concern, a situation exploited by both the intelligence and surveillance broker sectors, dogmatic sanctimony for high security is a feature and not a bug.
Re: GrapheneOS says Pixel 11 has MTE support after all
#88It’s absurd that a small project like Graphene is able to run rings around a giant like Google in the security sphere. Almost makes you wonder if some of those vulnerabilities are intentionally allowed to exist. Vulnerabilities in the world’s most popular (by volume) mobile OS could provide a plausibly deniable global espionage backdoor.
99.9% od the code GrapheneOS uses and 100% of hardware (including one like Titan security chip handling storage encryption and key store) is from Google.
So what are you on about man - it's easy to take someone else's work and put tweaks on it that wouldn't work at scale.
Re: GrapheneOS says Pixel 11 has MTE support after all
#89Earlier quoted context omitted.
The perception that they are able to run rings around Google is not necessarily an accurate one. There are tradeoffs in any engineering situation and GrapheneOS devs make different ones based on different requirements. Google is one of the reasons MTE even exists. I don't think GrapheneOS devs would be capable of helping push forward that technology in the same capacity.
Do we know if Google is operating on the frontier of the trade-off curve? What do we lose from Pixel Android when GrapheneOS security changes are made?
Actually functionality, stability of apps and features people use.
Re: GrapheneOS says Pixel 11 has MTE support after all
#90Unfortunately, the headline is somewhat optimistic compared to the reality, I think. The thread makes it sound like it could have been disabled due to errata or performance issues. Basically, it looks like the software Google is shipping intentionally doesn't use MTE on the Pixel 11 hardware. That raises the question of...what does Google know is wrong with MTE on the Pixel 11?
> it looks like the software Google is shipping intentionally doesn't use MTE on the Pixel 11 hardware. That raises the question of...what does Google know is wrong with MTE on the Pixel 11?
Apple replaced MTE with an upgraded version that can run in synchronous mode all the time without the performance hit.
> Consider that MTE can be configured to report memory corruption either synchronously or asynchronously. In the latter mode, memory corruption doesn’t immediately raise an exception, leaving a race window open for attackers... We believe memory safety protections need to be strictly synchronous, on by default, and working continuously.
https://security.apple.com/blog/memory-integrity-enforcement...
Google may just be getting ready to follow suit.