Re: [PATCH 20/24] bpf: Restrict kernel image access functions when the kernel is locked down

From	David Howells <dhowells@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 20/24] bpf: Restrict kernel image access functions when the kernel is locked down
Date	2017-04-13 10:50 +0200
Message-ID	<tvIBY-oq-11@gated-at.bofh.it> (permalink)
References	<tteI3-8tl-45@gated-at.bofh.it> <tsZzj-7hF-5@gated-at.bofh.it> <tsZzl-7hF-37@gated-at.bofh.it> <tteI3-8tl-45@gated-at.bofh.it>
Organization	Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

Show all headers | View raw

Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:

> this will obviously break the program.

Yeah.  But if it allows one to twiddle the kernel image or gain access to
crypto material...

> How about disabling loading tracing programs during the lockdown completely?

Interesting thought.  I'm not sure how much would actually need locking down
here.  Turning on tracepoints in the kernel and reading out of the trace
buffer, for example, ought to be okay, though if there are any tracepoints
that leak crypto information, they may need locking down also.

Basically, I think it boils down to: if it can be used to modify the kernel
image or read arbitrary data from the kernel image then should probably be
forbidden.  There have to be exceptions, though, such as loading authenticated
kernel modules.

David

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

Re: [PATCH 20/24] bpf: Restrict kernel image access functions when the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-13 10:50 +0200

csiph-web