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Re: Bug#605090: Linux 3.2 in wheezy

Am 03.02.2012 03:15, schrieb Russell Coker:
Some shared libraries have code which can't be run without an executable stack, it's a small number of libraries that are written in assembler code. We want to allow running them but don't want to give all programs permission
to execute code on the stack.

From memory the GR Security option for this was to flag the rare executables
that want an executable stack and are permitted to have it.

The solution devised by libc/gcc upstream was to have a special assembly
section in every shared object that doesn't require an executable
stack and if
an executable only loads shared objects that don't require it then the executable stack is disabled. Then we have SE Linux policy to prevent most
programs from having an executable stack which means that if they are
into loading some of the rare libraries that need it then it doesn't do
anything bad.

The downside to the latter approach is that lots of shared objects
which have
some assembler code needed to be patched.

The PaX approach involved less work.

Thanks for the insight :-)

But I guess you see what I meant... it's quite some job to get all this known and working. Therefore I really liked the original idea of having a -grsec kernel (and yes, I know the additional burden this places on our maintainers and the security team).

Actually I'd like even more to see perhaps just PaX in the default kernel; this could be easier than adding the full grsec suite.


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