netdev - [PATCH net-next] net: Make RX-FCS and LRO mutually exclusive

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1520165524-6953-1-git-send-email-galp@mellanox.com>
Date:   Sun,  4 Mar 2018 14:12:04 +0200
From:   Gal Pressman <galp@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Tariq Toukan <tariqt@...lanox.com>,
        Gal Pressman <galp@...lanox.com>
Subject: [PATCH net-next] net: Make RX-FCS and LRO mutually exclusive

LRO and RX-FCS offloads cannot be enabled at the same time since it is
not clear what should happen to the FCS of each coalesced packet.
The FCS is not really part of the TCP payload, hence cannot be merged
into one big packet. On the other hand, providing one big LRO packet
with one FCS contradicts the RX-FCS feature goal.

Use the fix features mechanism in order to prevent intersection of the
features and drop LRO in case RX-FCS is requested.

Enabling RX-FCS while LRO is enabled will result in:
$ ethtool -K ens6 rx-fcs on
Actual changes:
large-receive-offload: off [requested on]
rx-fcs: on

Signed-off-by: Gal Pressman <galp@...lanox.com>
Reviewed-by: Tariq Toukan <tariqt@...lanox.com>
---
 net/core/dev.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index c9d3058..1bc3792 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7542,6 +7542,12 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
 		}
 	}
 
+	/* LRO feature cannot be combined with RX-FCS */
+	if ((features & NETIF_F_LRO) && (features & NETIF_F_RXFCS)) {
+		netdev_dbg(dev, "Dropping LRO feature since RX-FCS is requested.\n");
+		features &= ~NETIF_F_LRO;
+	}
+
 	return features;
 }
 
-- 
2.7.4