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

Stephen Hemminger stephen at networkplumber.org
Mon Mar 25 23:42:21 UTC 2019

On Mon, 25 Mar 2019 15:09:50 -0700
Matthew Garrett <matthewgarrett at google.com> wrote:

> From: David Howells <dhowells at 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.
> Completely prohibit the use of BPF when the kernel is locked down.
> Suggested-by: Alexei Starovoitov <alexei.starovoitov at gmail.com>
> Signed-off-by: David Howells <dhowells at redhat.com>
> cc: netdev at vger.kernel.org
> cc: Chun-Yi Lee <jlee at suse.com>
> cc: Alexei Starovoitov <alexei.starovoitov at gmail.com>
> Cc: Daniel Borkmann <daniel at iogearbox.net>
> Signed-off-by: Matthew Garrett <matthewgarrett at google.com>

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

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