On Mon, Jan 20, 2020 at 2:11 PM Daniel Borkmann [off-list ref] wrote:

On 1/20/20 9:10 PM, Matt Cover wrote:

quoted

On Mon, Jan 20, 2020 at 11:11 AM Matt Cover [off-list ref] wrote:

quoted

On Sat, Jan 18, 2020 at 8:05 PM John Fastabend [off-list ref] wrote:

quoted

Matthew Cover wrote:

quoted

Allow looking up an nf_conn. This allows eBPF programs to leverage
nf_conntrack state for similar purposes to socket state use cases,
as provided by the socket lookup helpers. This is particularly
useful when nf_conntrack state is locally available, but socket
state is not.

Signed-off-by: Matthew Cover <redacted>
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Couple coding comments below. Also looks like a couple build errors
so fix those up. I'm still thinking over this though.

Thank you for taking the time to look this over. I will be looking
into the build issues.

Looks like I missed static inline on a couple functions when
nf_conntrack isn't builtin. I'll include the fix in v2.

One of the big issues I'd see with this integration is that literally no-one
will be able to use it unless they manually recompile their distro kernel with
ct as builtin instead of module .. Have you considered writing a tcp/udp ct in
plain bpf? Perhaps would make sense to have some sort of tools/lib/bpf/util/
with bpf prog library code that can be included.

Daniel, sorry, I missed addressing your second point in my previous
response. I agree that plain bpf ct is of interest. However, I still
see value in these helpers, particularly when nf_conntrack is
already in use. Reuse of info already in nf_conntrack avoids the
memory cost of another ct table.