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

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/ (local)

Cc: Andrii Nakryiko <redacted>
Cc: Stanislav Fomichev <redacted>

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(-)

-- 
2.25.4