[bpf-next,v5,00/11] sockmap: introduce BPF_SK_SKB_VERDICT and support UDP

Message

Cong Wang March 17, 2021, 2:22 a.m. UTC

From: Cong Wang <[e-mail]>

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, ->read_sock() is required for each protocol to support
sockmap redirection, and in order to do sock proto update, a new ops
->psock_update_sk_prot() is introduced, which is also required. And the
BPF ->recvmsg() is also needed to replace the original ->recvmsg() to
retrieve skmsg. To make life easier, we have to get rid of lock_sock()
in sk_psock_handle_skb(), otherwise we would have to implement
->sendmsg_locked() on top of ->sendmsg(), which is ugly.

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

---
v5: use INDIRECT_CALL_2() for function pointers
    use ingress_lock to close a race condition found by Jacub
    rename two helper functions

v4: get rid of lock_sock() in sk_psock_handle_skb()
    get rid of udp_sendmsg_locked()
    remove an empty line
    update cover letter

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 (11):
  skmsg: lock ingress_skb when purging
  skmsg: introduce a spinlock to protect ingress_msg
  skmsg: introduce skb_send_sock() for sock_map
  skmsg: avoid lock_sock() in sk_psock_backlog()
  sock_map: introduce BPF_SK_SKB_VERDICT
  sock: introduce sk->sk_prot->psock_update_sk_prot()
  udp: implement ->read_sock() for sockmap
  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/skbuff.h                        |   1 +
 include/linux/skmsg.h                         |  71 ++++++--
 include/net/sock.h                            |   3 +
 include/net/tcp.h                             |   3 +-
 include/net/udp.h                             |   3 +
 include/uapi/linux/bpf.h                      |   1 +
 kernel/bpf/syscall.c                          |   1 +
 net/core/skbuff.c                             |  55 +++++-
 net/core/skmsg.c                              | 160 +++++++++++++++---
 net/core/sock_map.c                           |  53 +++---
 net/ipv4/af_inet.c                            |   1 +
 net/ipv4/tcp_bpf.c                            | 130 +++-----------
 net/ipv4/tcp_ipv4.c                           |   3 +
 net/ipv4/udp.c                                |  38 +++++
 net/ipv4/udp_bpf.c                            |  79 ++++++++-
 net/ipv6/af_inet6.c                           |   1 +
 net/ipv6/tcp_ipv6.c                           |   3 +
 net/ipv6/udp.c                                |   3 +
 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 +++
 24 files changed, 600 insertions(+), 178 deletions(-)