linux-kernel - Re: [PATCH net-next 1/2] bpf: enable non-root eBPF programs

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Date:	Thu, 8 Oct 2015 08:21:55 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Alexei Starovoitov <ast@...mgrid.com>
Cc:	Kees Cook <keescook@...omium.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	"David S. Miller" <davem@...emloft.net>,
	Andy Lutomirski <luto@...capital.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Linux API <linux-api@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 1/2] bpf: enable non-root eBPF programs


* Alexei Starovoitov <ast@...mgrid.com> wrote:

> As far as sysctl we can look at two with similar purpose:
> sysctl_perf_event_paranoid and modules_disabled.
> First one is indeed multi level, but not because of the fear of bugs,
> but because of real security implications.

It serves both purposes flexibly, and note that most people and distros will use 
the default value.

> [...] Like raw events on hyperthreaded cpu or uncore events can extract data 
> from other user processes. So it controls these extra privileges.

It also controls the generally increased risk caused by a larger attack surface, 
which some users may not want to carry and which they can thus shrink.

With a static keys approach there would be no runtime overhead worth speaking of, 
so I see no reason why unprivileged eBPF couldn't have a sysctl too - with the 
default value set to permissive.

Thanks,

	Ingo
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