On Monday 25 March 2013 03:01:51 Kfir Lavi wrote: > I'm looking for a way to reduce glibc code size. > It can be a way to make system smaller and minimize the impact > of attack vectors in glibc, as in return-to-libc attack. > > Lets say I'm deleting the program 'mkdir', and mkdir uses a function > in glibc that non of the other parts of the system uses. > Then I want to eliminate this function from glibc. This leads to smaller > code and if this function is used in some attack scenario, maybe prevent > it. > > Is there a way to do it? > Can you help me think how to build a tool like this? or, integrate > with existing tools.
the only thing i've seen in the past was a hacky script that utilize the uClibc build system to cull objects until things stopped linking. it had very constrained use where i'd safely work, and was never generalized. i don't remember the name of it now (was a few years ago), but having read the [limited] source, i wouldn't bother using it as a base. otherwise, i haven't heard of any tools that do what you want, but i've seen many people request it. unfortunately, it's a tough nut to crack, and the vast majority of people requesting it didn't have the technical skills to even think about a solution let alone implement it. i [pessimistically] suspect we're talking many man months here, and the skill set involves knowledge of the ELF format at a fairly low level. -mike
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