Messages in this thread | | | Date | Thu, 08 Mar 2018 21:31:53 -0500 (EST) | Subject | Re: [PATCH net-next] modules: allow modprobe load regular elf binaries | From | David Miller <> |
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From: Andy Lutomirski <luto@kernel.org> Date: Fri, 9 Mar 2018 02:12:24 +0000
> First, compile your user code and emit a staitc binary. Use objdump > fiddling or a trivial .S file to make that static binary into a > variable. Then write a tiny shim module like this: > > extern unsigned char __begin_user_code[], __end_user_code[]; > > int __init init_shim_module(void) > { > return call_umh_blob(__begin_user_code, __end_user_code - __begin_user_code); > } > > By itself, this is clearly a worse solution than yours, but it has two > benefits, one small and two big. The small benefit is that it is > completely invisible to userspace: the .ko file is a bona fide module.
Anything you try to do which makes these binaries "special" is a huge negative.
> The big benefits are:
I don't see those things as benefits at all, and Alexei's scheme can easily be made to work in your benefit #1 case too.
It's a user binary. It's shipped with the kernel and it's signed.
If we can't trust that, we can't trust much else.
And this whole container argument.. It's a mirage.
Kernel modules are 1000 times worse, since they can access any container and any namespace they want.
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