Query on DCL

ACuriousFellow

I've got a few apps I've had to allow for DCL. Whilst I could ask the developers of these apps to change, there is a chance they won't.

I was wondering if anyone had a link to the code surrounding this?

The reason I ask is I wanted to see if there was potential to add some kind of white list / local routing functionality ?

This could negate some of the risk as the user can then allow on first install and then go a stage further to cache it locally.

I'd really like to hear the community and the devs opinion on this

ignoramous

ACuriousFellow was wondering if anyone had a link to the code surrounding this?

For Java/Kotlin, you may be able to fstat dexfiles for ctime and prevent DCL from within ART: https://github.com/LineageOS/android_art/blob/0abc6e9ecd0bd/runtime/native/dalvik_system_DexFile.cc#L368

For native code, you may have success with fstat + ctime on fd of the just opened dynamic library in bionic's ld: https://github.com/LineageOS/android_bionic/blob/53baa8eac64027ea286e7d98502e785a7bb8a254/linker/linker.cpp#L1352

The idea is, DCLd dexfiles (or .so) with ctimes later than the time much after app install / update should be disallowed?

Ideally, ctime for DCLd dexfile should be greater than ctime for other unmodified dexfiles (though, I'm unsure if DCLd code is also optimized, in which case ctime would cease to be a good indicator, as ART would keep patching the dexfile / oatfile inplace with quickened / optimised / native code depending on PGO).

ACuriousFellow

ignoramous thanks so much. I see the links are to linageOS. Do you have links to the code in grapheme repos?

Thanks again