netdev - Re: [PATCH bpf-next v2 0/3] bpf, netns: Prepare for multi-prog attachment

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Date:   Mon, 29 Jun 2020 16:56:55 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jakub Sitnicki <jakub@...udflare.com>, bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, kernel-team@...udflare.com,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Stanislav Fomichev <sdf@...gle.com>
Subject: Re: [PATCH bpf-next v2 0/3] bpf, netns: Prepare for multi-prog
 attachment

On 6/23/20 12:34 PM, Jakub Sitnicki wrote:
> This patch set prepares ground for link-based multi-prog attachment for
> future netns attach types, with BPF_SK_LOOKUP attach type in mind [0].
> 
> Two changes are needed in order to attach and run a series of BPF programs:
> 
>    1) an bpf_prog_array of programs to run (patch #2), and
>    2) a list of attached links to keep track of attachments (patch #3).
> 
> I've been using these patches with the next iteration of BPF socket lookup
> hook patches, and saw that they are self-contained and can be split out to
> ease the review burden.
> 
> Nothing changes for BPF flow_dissector. That is at most one prog can be
> attached.
> 
> Thanks,
> -jkbs
> 
> [0] https://lore.kernel.org/bpf/20200511185218.1422406-1-jakub@cloudflare.com/
> 
> Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
> Cc: Stanislav Fomichev <sdf@...gle.com>
> 
> v1 -> v2:
> 
> - Show with a (void) cast that bpf_prog_array_replace_item() return value
>    is ignored on purpose. (Andrii)
> - Explain why bpf-cgroup cannot replace programs in bpf_prog_array based
>    on bpf_prog pointer comparison in patch #2 description. (Andrii)
> 
> Jakub Sitnicki (3):
>    flow_dissector: Pull BPF program assignment up to bpf-netns
>    bpf, netns: Keep attached programs in bpf_prog_array
>    bpf, netns: Keep a list of attached bpf_link's
> 
>   include/linux/bpf.h          |   3 +
>   include/net/flow_dissector.h |   3 +-
>   include/net/netns/bpf.h      |   7 +-
>   kernel/bpf/core.c            |  20 +++-
>   kernel/bpf/net_namespace.c   | 189 +++++++++++++++++++++++++----------
>   net/core/flow_dissector.c    |  34 +++----
>   6 files changed, 173 insertions(+), 83 deletions(-)
> 

Applied, thanks!