From: John Fastabend john.fastabend@gmail.com
[ Upstream commit 6df7f764cd3cf5a03a4a47b23be47e57e41fcd85 ]
When TCP stack has data ready to read sk_data_ready() is called. Sockmap overwrites this with its own handler to call into BPF verdict program. But, the original TCP socket had sock_def_readable that would additionally wake up any user space waiters with sk_wake_async().
Sockmap saved the callback when the socket was created so call the saved data ready callback and then we can wake up any epoll() logic waiting on the read.
Note we call on 'copied >= 0' to account for returning 0 when a FIN is received because we need to wake up user for this as well so they can do the recvmsg() -> 0 and detect the shutdown.
Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()") Signed-off-by: John Fastabend john.fastabend@gmail.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Jakub Sitnicki jakub@cloudflare.com Link: https://lore.kernel.org/bpf/20230523025618.113937-8-john.fastabend@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/skmsg.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c index d3ffca1b96462..062612ee508c0 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1196,10 +1196,19 @@ static int sk_psock_verdict_recv(struct sock *sk, struct sk_buff *skb) static void sk_psock_verdict_data_ready(struct sock *sk) { struct socket *sock = sk->sk_socket; + int copied;
if (unlikely(!sock || !sock->ops || !sock->ops->read_skb)) return; - sock->ops->read_skb(sk, sk_psock_verdict_recv); + copied = sock->ops->read_skb(sk, sk_psock_verdict_recv); + if (copied >= 0) { + struct sk_psock *psock; + + rcu_read_lock(); + psock = sk_psock(sk); + psock->saved_data_ready(sk); + rcu_read_unlock(); + } }
void sk_psock_start_verdict(struct sock *sk, struct sk_psock *psock)