[PATCH net-next v2 0/2] net: tcp: add skb drop reasons to connect request

[menglong8.dong@gmail.com]

From: Menglong Dong <imagedong@tencent.com>

Seems now the reasons of skb drop in TCP layer are almost supported,
except the path of connect requesting. So let's just finish it.

The TCP connect requesting is processed by
'inet_csk(sk)->icsk_af_ops->conn_request()'. Yeah, it's a function
pointer, so it's not easy to add function param to it. Luckily, it's
return value can be reused. For now, 0 means a call of 'consume_skb()'
and -1 means 'kfree_skb()', with a RESET be send. Therefore, we can
return the drop reasons directly, as the positive is not used yet. With
drop reasons returned, kfree_skb_reason() will be called instead of
consume_skb() in tcp_rcv_state_process().

And in the 2th patch, skb drop reasons are added to route_req() in
struct tcp_request_sock_ops by adding a function param to it.

Following new skb drop reasons are added:

  SKB_DROP_REASON_LISTENOVERFLOWS
  SKB_DROP_REASON_TCP_REQQFULLDROP
  SKB_DROP_REASON_SECURITY

Changes since v1:
- don't free skb in conn_request, as Eric suggested, and use it's
  return value to pass drop reasons in the 1th patch.

Menglong Dong (2):
  net: tcp: add skb drop reasons to tcp connect request
  net: tcp: add skb drop reasons to route_req()

 include/linux/skbuff.h     |  5 +++++
 include/net/tcp.h          |  3 ++-
 include/trace/events/skb.h |  3 +++
 net/ipv4/tcp_input.c       | 22 +++++++++++++++-------
 net/ipv4/tcp_ipv4.c        | 16 ++++++++++++----
 net/ipv6/tcp_ipv6.c        | 18 +++++++++++++-----
 net/mptcp/subflow.c        | 10 ++++++----
 7 files changed, 56 insertions(+), 21 deletions(-)

-- 
2.36.0