Messages in this thread | | | Subject | Re: [PATCH 23/27] bpf: Restrict kernel image access functions when the kernel is locked down | From | Daniel Borkmann <> | Date | Tue, 26 Mar 2019 01:00:29 +0100 |
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On 03/26/2019 12:42 AM, Stephen Hemminger wrote: > On Mon, 25 Mar 2019 15:09:50 -0700 > Matthew Garrett <matthewgarrett@google.com> wrote: > >> From: David Howells <dhowells@redhat.com> >> >> There are some bpf functions can be used to read kernel memory: >> bpf_probe_read, bpf_probe_write_user and bpf_trace_printk. These allow >> private keys in kernel memory (e.g. the hibernation image signing key) to >> be read by an eBPF program and kernel memory to be altered without >> restriction.
I'm not sure where 'kernel memory to be altered without restriction' comes from, but it's definitely a wrong statement.
>> Completely prohibit the use of BPF when the kernel is locked down.
In which scenarios will the lock-down mode be used? Mostly niche? I'm asking as this would otherwise break a lot of existing stuff ... I'd prefer you find a better solution to this than this straight -EPERM rejection.
>> Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> >> Signed-off-by: David Howells <dhowells@redhat.com> >> cc: netdev@vger.kernel.org >> cc: Chun-Yi Lee <jlee@suse.com> >> cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> >> Cc: Daniel Borkmann <daniel@iogearbox.net> >> Signed-off-by: Matthew Garrett <matthewgarrett@google.com> > > Wouldn't this mean that Seccomp won't work in locked down mode? >
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