[Patch bpf-next v3 0/9] sockmap: introduce BPF_SK_SKB_VERDICT and support UDP

[Cong Wang <xiyou.wangcong@gmail.com>]

From: Cong Wang <cong.wang@bytedance.com>

We have thousands of services connected to a daemon on every host
via AF_UNIX dgram sockets, after they are moved into VM, we have to
add a proxy to forward these communications from VM to host, because
rewriting thousands of them is not practical. This proxy uses an
AF_UNIX socket connected to services and a UDP socket to connect to
the host. It is inefficient because data is copied between kernel
space and user space twice, and we can not use splice() which only
supports TCP. Therefore, we want to use sockmap to do the splicing
without going to user-space at all (after the initial setup).

Currently sockmap only fully supports TCP, UDP is partially supported
as it is only allowed to add into sockmap. This patchset, as the second
part of the original large patchset, extends sockmap with:
1) cross-protocol support with BPF_SK_SKB_VERDICT; 2) full UDP support.

On the high level, ->sendmsg_locked() and ->read_sock() are required
for each protocol to support sockmap redirection, and in order to do
sock proto update, a new ops ->update_proto() is introduced, which is
also required to implement. A BPF ->recvmsg() is also needed to replace
the original ->recvmsg() to retrieve skmsg. Please see each patch for
more details.

To see the big picture, the original patchset is available here:
https://github.com/congwang/linux/tree/sockmap
this patchset is also available:
https://github.com/congwang/linux/tree/sockmap2

---
v3: export tcp/udp_update_proto()
    rename sk->sk_prot->psock_update_sk_prot()
    improve changelogs

v2: separate from the original large patchset
    rebase to the latest bpf-next
    split UDP test case
    move inet_csk_has_ulp() check to tcp_bpf.c
    clean up udp_read_sock()

Cong Wang (9):
  sock_map: introduce BPF_SK_SKB_VERDICT
  sock: introduce sk->sk_prot->psock_update_sk_prot()
  udp: implement ->sendmsg_locked()
  udp: implement ->read_sock() for sockmap
  udp: add ->read_sock() and ->sendmsg_locked() to ipv6
  skmsg: extract __tcp_bpf_recvmsg() and tcp_bpf_wait_data()
  udp: implement udp_bpf_recvmsg() for sockmap
  sock_map: update sock type checks for UDP
  selftests/bpf: add a test case for udp sockmap

 include/linux/skmsg.h                         |  25 ++--
 include/net/ipv6.h                            |   1 +
 include/net/sock.h                            |   3 +
 include/net/tcp.h                             |   3 +-
 include/net/udp.h                             |   4 +
 include/uapi/linux/bpf.h                      |   1 +
 kernel/bpf/syscall.c                          |   1 +
 net/core/skmsg.c                              | 113 +++++++++++++-
 net/core/sock_map.c                           |  52 ++++---
 net/ipv4/af_inet.c                            |   2 +
 net/ipv4/tcp_bpf.c                            | 130 +++-------------
 net/ipv4/tcp_ipv4.c                           |   3 +
 net/ipv4/udp.c                                |  68 ++++++++-
 net/ipv4/udp_bpf.c                            |  79 +++++++++-
 net/ipv6/af_inet6.c                           |   2 +
 net/ipv6/tcp_ipv6.c                           |   3 +
 net/ipv6/udp.c                                |  30 +++-
 net/tls/tls_sw.c                              |   4 +-
 tools/bpf/bpftool/common.c                    |   1 +
 tools/bpf/bpftool/prog.c                      |   1 +
 tools/include/uapi/linux/bpf.h                |   1 +
 .../selftests/bpf/prog_tests/sockmap_listen.c | 140 ++++++++++++++++++
 .../selftests/bpf/progs/test_sockmap_listen.c |  22 +++
 23 files changed, 519 insertions(+), 170 deletions(-)

-- 
2.25.1