[PATCH 5.4 122/222] bpf/sockmap: Read psock ingress_msg before sk_receive_queue

Greg Kroah-Hartman
2020-01-22T13:22:46Z

From: Lingpeng Chen <forrest0579@gmail.com>

commit e7a5f1f1cd0008e5ad379270a8657e121eedb669 upstream.

Right now in tcp_bpf_recvmsg, sock read data first from sk_receive_queue
if not empty than psock->ingress_msg otherwise. If a FIN packet arrives
and there's also some data in psock->ingress_msg, the data in
psock->ingress_msg will be purged. It is always happen when request to a
HTTP1.0 server like python SimpleHTTPServer since the server send FIN
packet after data is sent out.

Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Reported-by: Arika Chen <eaglesora@gmail.com>
Suggested-by: Arika Chen <eaglesora@gmail.com>
Signed-off-by: Lingpeng Chen <forrest0579@gmail.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200109014833.18951-1-forrest0579@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/ipv4/tcp_bpf.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -121,14 +121,14 @@ int tcp_bpf_recvmsg(struct sock *sk, str
struct sk_psock *psock;
int copied, ret;

- if (unlikely(flags & MSG_ERRQUEUE))
- return inet_recv_error(sk, msg, len, addr_len);
- if (!skb_queue_empty(&sk->sk_receive_queue))
- return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
-
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
+ if (unlikely(flags & MSG_ERRQUEUE))
+ return inet_recv_error(sk, msg, len, addr_len);
+ if (!skb_queue_empty(&sk->sk_receive_queue) &&
+ sk_psock_queue_empty(psock))
+ return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
lock_sock(sk);
msg_bytes_ready:
copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags);
@@ -139,7 +139,7 @@ msg_bytes_ready:
timeo = sock_rcvtimeo(sk, nonblock);
data = tcp_bpf_wait_data(sk, psock, flags, timeo, &err);
if (data) {
- if (skb_queue_empty(&sk->sk_receive_queue))
+ if (!sk_psock_queue_empty(psock))
goto msg_bytes_ready;
release_sock(sk);
sk_psock_put(sk, psock);