[PATCH bpf-next 0/2] bpf/flow_dissector: add mode to enforce global BPF flow dissector

[Stanislav Fomichev <sdf@google.com>]

While having a per-net-ns flow dissector programs is convenient for
testing, security-wise it's better to have only one vetted global
flow dissector implementation.

Let's have a convention that when BPF flow dissector is installed
in the root namespace, child namespaces can't override it.

Note, that it's totally possible to attach flow_dissector programs
to several namespaces and then switch to a global one. In this case,
only the root one will trigger; users are still able to detach
flow_dissector programs from non-root namespaces.

Alternative solution might be something like a sysctl to enable
the global mode.

Cc: Petar Penkov <ppenkov@google.com>

Stanislav Fomichev (2):
  bpf/flow_dissector: add mode to enforce global BPF flow dissector
  selftests/bpf: add test for BPF flow dissector in the root namespace

 Documentation/bpf/prog_flow_dissector.rst     |  3 ++
 net/core/flow_dissector.c                     | 11 ++++-
 .../selftests/bpf/test_flow_dissector.sh      | 48 ++++++++++++++++---
 3 files changed, 55 insertions(+), 7 deletions(-)

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2.23.0.444.g18eeb5a265-goog