linux-kernel - [PATCH 5.2 37/66] net/tls: fix poll ignoring partially copied records

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Message-Id: <20190726152306.042706186@linuxfoundation.org>
Date:   Fri, 26 Jul 2019 17:24:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        David Beckett <david.beckett@...ronome.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Dirk van der Merwe <dirk.vandermerwe@...ronome.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.2 37/66] net/tls: fix poll ignoring partially copied records

From: Jakub Kicinski <jakub.kicinski@...ronome.com>

[ 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 <david.beckett@...ronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@...ronome.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/tls/tls_sw.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -1958,7 +1958,8 @@ bool tls_sw_stream_read(const struct soc
 		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)