mac80211: Fix monitor MTU limit so that A-MSDUs get through

[ Upstream commit 79f5962baea74ce1cd4e5949598944bff854b166 ]

The maximum MTU was set to 2304, which is the maximum MSDU size. While
this is valid for normal WLAN interfaces, it is too low for monitor
interfaces. A monitor interface may receive and inject MPDU frames, and
the maximum MPDU frame size is larger than 2304. The MPDU may also
contain an A-MSDU frame, in which case the size may be much larger than
the MTU limit. Since the maximum size of an A-MSDU depends on the PHY
mode of the transmitting STA, it is not possible to set an exact MTU
limit for a monitor interface. Now the maximum MTU for a monitor
interface is unrestricted.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Link: https://lore.kernel.org/r/20210628123246.2070558-1-johan.almbladh@anyfinetworks.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Johan Almbladh 2021-06-28 14:32:46 +02:00 committed by Greg Kroah-Hartman
parent 1e2842fb7e
commit a66049c5ff

View File

@ -1875,9 +1875,16 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
netdev_set_default_ethtool_ops(ndev, &ieee80211_ethtool_ops);
/* MTU range: 256 - 2304 */
/* MTU range is normally 256 - 2304, where the upper limit is
* the maximum MSDU size. Monitor interfaces send and receive
* MPDU and A-MSDU frames which may be much larger so we do
* not impose an upper limit in that case.
*/
ndev->min_mtu = 256;
ndev->max_mtu = local->hw.max_mtu;
if (type == NL80211_IFTYPE_MONITOR)
ndev->max_mtu = 0;
else
ndev->max_mtu = local->hw.max_mtu;
ret = register_netdevice(ndev);
if (ret) {