Re: [PATCH 23/27] bpf: Restrict kernel image access functions when the kernel is locked down

From: Stephen Hemminger
Date: Mon Mar 25 2019 - 19:42:28 EST

On Mon, 25 Mar 2019 15:09:50 -0700
Matthew Garrett <matthewgarrett@xxxxxxxxxx> wrote:

> From: David Howells <dhowells@xxxxxxxxxx>
> 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.
> Completely prohibit the use of BPF when the kernel is locked down.
> Suggested-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: netdev@xxxxxxxxxxxxxxx
> cc: Chun-Yi Lee <jlee@xxxxxxxx>
> cc: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Signed-off-by: Matthew Garrett <matthewgarrett@xxxxxxxxxx>

Wouldn't this mean that Seccomp won't work in locked down mode?