bpf: Add sock_ops RTO callback

Adds an optional call to sock_ops BPF program based on whether the
BPF_SOCK_OPS_RTO_CB_FLAG is set in bpf_sock_ops_flags.
The BPF program is passed 2 arguments: icsk_retransmits and whether the
RTO has expired.

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 6db3124cdbda..257abdde23b0 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -213,11 +213,18 @@ static int tcp_write_timeout(struct sock *sk)
                                                 icsk->icsk_user_timeout);
         }
         tcp_fastopen_active_detect_blackhole(sk, expired);
+
+        if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG))
+                tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB,
+                                  icsk->icsk_retransmits,
+                                  icsk->icsk_rto, (int)expired);
+
         if (expired) {
                 /* Has it gone just too far? */
                 tcp_write_err(sk);
                 return 1;
         }
+
         return 0;
 }