From: Greg KH gregkh@linuxfoundation.org Date: Thu, 18 Aug 2022 16:11:10 +0200
On Thu, Aug 18, 2022 at 03:56:29PM +0200, Alexander Lobakin wrote:
From: Greg KH gregkh@linuxfoundation.org Date: Thu, 18 Aug 2022 14:23:43 +0200
On Thu, Aug 18, 2022 at 01:53:06PM +0200, Alexander Lobakin wrote:
Currently, kallsyms kernel code copes with symbols with the same name by indexing them according to their position in vmlinux and requiring to provide an index of the desired symbol. This is not really quite reliable and is fragile to any features performing symbol or section manipulations such as FG-KASLR.
Ah, here's the reasoning, stuff like this should go into the 0/X message too, right?
Anyway, what is currently broken that requires this? What will this make easier in the future? What in the future will depend on this?
- FG-KASLR will depend and probably some more crazy hardening stuff. And/or perf-based function/symbol placement, which is in the "discuss and dream sometimes" stage.
I have no idea what "FG-KASLR" is. Why not submit these changes when whatever that is is ready for submission?
It doesn't matter much, the main idea is that the current approach with relying on symbol positions in the vmlinux is broken when we reorder symbols during the kernel initialization. As I said, this is an early RFC do discuss the idea and the implementation. I could submit it along with FG-KASLR, but then if there would be major change requests, I'd need to redo lots of stuff, which is not very efficient. It's better to settle down the implementation details in advance. Plus this kallsyms feature goes standalone as it gets bigger. It will contain a pack of commits and touch several different subsystems. Mixing all of this with FG-KASLR in one series doesn't sound good to me.
thanks,
greg k-h
Thanks, Olek