bpf: Add support for changing congestion control

Added support for changing congestion control for SOCK_OPS bpf
programs through the setsockopt bpf helper function. It also adds
a new SOCK_OPS op, BPF_SOCK_OPS_NEEDS_ECN, that is needed for
congestion controls, like dctcp, that need to enable ECN in the
SYN packets.

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 664210e5e4a7..2920e0cb09f8 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6191,7 +6191,8 @@ static void tcp_ecn_create_request(struct request_sock *req,
         ecn_ok = net->ipv4.sysctl_tcp_ecn || ecn_ok_dst;
 
         if ((!ect && ecn_ok) || tcp_ca_needs_ecn(listen_sk) ||
-            (ecn_ok_dst & DST_FEATURE_ECN_CA))
+            (ecn_ok_dst & DST_FEATURE_ECN_CA) ||
+            tcp_bpf_ca_needs_ecn((struct sock *)req))
                 inet_rsk(req)->ecn_ok = 1;
 }