bpf: sockmap, add sock close() hook to remove socks

The selftests test_maps program was leaving dangling BPF sockmap
programs around because not all psock elements were removed from
the map. The elements in turn hold a reference on the BPF program
they are attached to causing BPF programs to stay open even after
test_maps has completed.

The original intent was that sk_state_change() would be called
when TCP socks went through TCP_CLOSE state. However, because
socks may be in SOCK_DEAD state or the sock may be a listening
socket the event is not always triggered.

To resolve this use the ULP infrastructure and register our own
proto close() handler. This fixes the above case.

Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support")
Reported-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index a58292d31e12..e3fc667f9ac2 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1985,6 +1985,7 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
 
 enum {
 	TCP_ULP_TLS,
+	TCP_ULP_BPF,
 };
 
 struct tcp_ulp_ops {
@@ -2003,6 +2004,7 @@ struct tcp_ulp_ops {
 int tcp_register_ulp(struct tcp_ulp_ops *type);
 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
 int tcp_set_ulp(struct sock *sk, const char *name);
+int tcp_set_ulp_id(struct sock *sk, const int ulp);
 void tcp_get_available_ulp(char *buf, size_t len);
 void tcp_cleanup_ulp(struct sock *sk);