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Date: Fri, 12 Oct 2018 20:23:15 +0200
From: Jann Horn <>
Cc: Kernel Hardening <>, 
	Daniel Borkmann <>, Kees Cook <>, 
	Catalin Marinas <>, Will Deacon <>, 
	"David S. Miller" <>, Thomas Gleixner <>, Ingo Molnar <>, 
	Borislav Petkov <>, "the arch/x86 maintainers" <>, Arnd Bergmann <>,,, 
	kernel list <>,, 
	linux-s390 <>,,, linux-arch <>,, Dave Hansen <>, 
	Arjan van de Ven <>,
Subject: Re: [PATCH v2 1/7] modules: Create rlimit for module space

On Fri, Oct 12, 2018 at 2:35 AM Jann Horn <> wrote:
> On Fri, Oct 12, 2018 at 1:40 AM Rick Edgecombe
> <> wrote:
> > This introduces a new rlimit, RLIMIT_MODSPACE, which limits the amount of
> > module space a user can use. The intention is to be able to limit module space
> > allocations that may come from un-privlidged users inserting e/BPF filters.
> Note that in some configurations (iirc e.g. the default Ubuntu
> config), normal users can use the subuid mechanism (the /etc/subuid
> config file and the /usr/bin/newuidmap setuid helper) to gain access
> to 65536 UIDs, which means that in such a configuration,
> RLIMIT_MODSPACE*65537 is the actual limit for one user. (Same thing
> applies to RLIMIT_MEMLOCK.)

Actually, I may have misremembered, perhaps it's not installed by
default - I just checked in a Ubuntu VM, and the newuidmap helper from
the uidmap package wasn't installed.

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