Subject: [PATCH 40/49] net/tls: fix poll ignoring partially copied records

From: Jakub Kicinski <[email-masked]>
Date: Thu, 4 Jul 2019 14:50:36 -0700

[ Upstream commit 13aecb17acabc2a92187d08f7ca93bb8aad62c6f ]

David reports that RPC applications which use epoll() occasionally
get stuck, and that TLS ULP causes the kernel to not wake applications,
even though read() will return data.

This is indeed true. The ctx->rx_list which holds partially copied
records is not consulted when deciding whether socket is readable.

Note that SO_RCVLOWAT with epoll() is and has always been broken for
kernel TLS. We'd need to parse all records from the TCP layer, instead
of just the first one.

Fixes: 692d7b5d1f91 ("tls: Fix recvmsg() to be able to peek across multiple records")
Reported-by: David Beckett <[email-masked]>
Signed-off-by: Jakub Kicinski <[email-masked]>
Reviewed-by: Dirk van der Merwe <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/tls/tls_sw.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 455a782c7658..e2385183526e 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -1958,7 +1958,8 @@ bool tls_sw_stream_read(const struct sock *sk)
 		ingress_empty = list_empty(&psock->ingress_msg);
 	rcu_read_unlock();
 
-	return !ingress_empty || ctx->recv_pkt;
+	return !ingress_empty || ctx->recv_pkt ||
+		!skb_queue_empty(&ctx->rx_list);
 }
 
 static int tls_read_size(struct strparser *strp, struct sk_buff *skb)
-- 
2.20.1