Re: [PATCH v2] module: Harden STRICT_MODULE_RWX

[Mauro Carvalho Chehab]

Em Tue, 11 Aug 2020 16:55:24 +0200
peterz@xxxxxxxxxxxxx escreveu:

> On Tue, Aug 11, 2020 at 04:34:27PM +0200, Mauro Carvalho Chehab wrote:
> >   [33] .plt              PROGBITS         0000000000000340  00035c80
> >        0000000000000001  0000000000000000 WAX       0     0     1
> >   [34] .init.plt         NOBITS           0000000000000341  00035c81
> >        0000000000000001  0000000000000000  WA       0     0     1
> >   [35] .text.ftrace[...] PROGBITS         0000000000000342  00035c81
> >        0000000000000001  0000000000000000 WAX       0     0     1  
> 
> .plt and .text.ftrace_tramplines are buggered.
> 
> arch/arm64/kernel/module.lds even marks then as NOLOAD.

Hmm... Shouldn't the code at module_enforce_rwx_sections() or at
load_module() ignore such sections instead of just rejecting probing
all modules?

I mean, if the existing toolchain is not capable of excluding
those sections, either the STRICT_MODULE_RWX hardening should be
disabled, if a broken toolchain is detected or some runtime code 
should handle such sections on a different way.

Thanks,
Mauro