Re: [PATCH bpf-next v5 0/6] Support direct writes to nf_conn:mark

Hi Kumar,

On Sat, Sep 10, 2022 at 02:27:38AM +0200, Kumar Kartikeya Dwivedi wrote:

On Wed, 7 Sept 2022 at 18:41, Daniel Xu [off-list ref] wrote:

quoted

Support direct writes to nf_conn:mark from TC and XDP prog types. This
is useful when applications want to store per-connection metadata. This
is also particularly useful for applications that run both bpf and
iptables/nftables because the latter can trivially access this metadata.

One example use case would be if a bpf prog is responsible for advanced
packet classification and iptables/nftables is later used for routing
due to pre-existing/legacy code.

There are a couple of compile time warnings when conntrack is disabled,

../net/core/filter.c:8608:1: warning: symbol 'nf_conn_btf_access_lock'
was not declared. Should it be static?
../net/core/filter.c:8611:5: warning: symbol 'nfct_bsa' was not
declared. Should it be static?

Most likely because extern declaration is guarded by ifdefs. So just
moving those out of ifdef should work.
I guess you can send that as a follow up fix, or roll it in if you end
up respinning.

Hmm, I don't see how filter.c ever #include's nf_conntrack_bpf.h. So
you'd think that the warning would always be present regardless of
CONFIG_NF_CONNTRACK setting.

FWIW I can't reproduce the warning even with CONFIG_NF_CONNTRACK=n.

Maybe the extern declarations should be in include/linux/filter.h
anyways? Might be cleaner. WDYT?

Otherwise, for the series:
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

Thanks!

Daniel