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From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
To: woojung.huh@microchip.com
Cc: UNGLinuxDriver@microchip.com, andrew@lunn.ch,
	vivien.didelot@gmail.com, f.fainelli@gmail.com,
	olteanv@gmail.com, davem@davemloft.net, kuba@kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Lino Sanfilippo <LinoSanfilippo@gmx.de>
Subject: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum
Date: Wed, 14 Jul 2021 21:17:23 +0200	[thread overview]
Message-ID: <20210714191723.31294-3-LinoSanfilippo@gmx.de> (raw)
In-Reply-To: <20210714191723.31294-1-LinoSanfilippo@gmx.de>

If the checksum calculation is offloaded to the network device (e.g due to
NETIF_F_HW_CSUM inherited from the DSA master device), the calculated
layer 4 checksum is incorrect. This is since the DSA tag which is placed
after the layer 4 data is seen as a part of the data portion and thus
errorneously included into the checksum calculation.
To avoid this, always calculate the layer 4 checksum in software.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
---
 net/dsa/tag_ksz.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 364f509d7cd7..d59f0e7019e2 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -56,6 +56,9 @@ static struct sk_buff *ksz8795_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (skb_linearize(skb))
 		return NULL;
 
+	if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
+		return NULL;
+
 	/* Tag encoding */
 	tag = skb_put(skb, KSZ_INGRESS_TAG_LEN);
 	addr = skb_mac_header(skb);
@@ -120,6 +123,9 @@ static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
 	if (skb_linearize(skb))
 		return NULL;
 
+	if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
+		return NULL;
+
 	/* Tag encoding */
 	tag = skb_put(skb, KSZ9477_INGRESS_TAG_LEN);
 	addr = skb_mac_header(skb);
@@ -173,6 +179,9 @@ static struct sk_buff *ksz9893_xmit(struct sk_buff *skb,
 	if (skb_linearize(skb))
 		return NULL;
 
+	if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
+		return NULL;
+
 	/* Tag encoding */
 	tag = skb_put(skb, KSZ_INGRESS_TAG_LEN);
 	addr = skb_mac_header(skb);
-- 
2.32.0


  parent reply	other threads:[~2021-07-14 19:18 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 19:17 [PATCH 0/2] Fixes for KSZ DSA switch Lino Sanfilippo
2021-07-14 19:17 ` [PATCH 1/2] net: dsa: tag_ksz: linearize SKB before adding DSA tag Lino Sanfilippo
2021-07-14 19:17 ` Lino Sanfilippo [this message]
2021-07-14 19:48   ` [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum Vladimir Oltean
2021-07-14 20:15     ` Andrew Lunn
2021-07-15  6:54       ` Vladimir Oltean
2021-07-15 11:16         ` Aw: " Lino Sanfilippo
2021-07-15 11:49           ` Vladimir Oltean
2021-07-15 13:04             ` Aw: " Lino Sanfilippo
2021-07-15 13:12               ` Vladimir Oltean
2021-07-15 13:34                 ` Aw: " Lino Sanfilippo
2021-07-15 13:08         ` Andrew Lunn
2021-07-15 14:36           ` Vladimir Oltean
2021-07-15 15:50             ` Andrew Lunn
2021-07-19  8:20             ` Aw: " Lino Sanfilippo
2021-07-19  8:24               ` Vladimir Oltean
2021-07-15 16:24           ` Florian Fainelli
2021-07-15 23:23 ` [PATCH 0/2] Fixes for KSZ DSA switch Florian Fainelli
2021-07-16  8:49   ` Aw: " Lino Sanfilippo

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