[PATCH AUTOSEL 5.10 037/217] mac80211: don't overwrite QoS TID of injected frames

Sasha Levin
2020-12-23T03:10:32Z

From: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>

[ Upstream commit 527d675969a1dff17baa270d4447ac1c87058299 ]

Currently ieee80211_set_qos_hdr sets the QoS TID of all frames based
on the value assigned to skb->priority. This means it will also
overwrite the QoS TID of injected frames. The commit 753ffad3d624
("mac80211: fix TID field in monitor mode transmit") prevented
injected frames from being modified because of this by setting
skb->priority to the TID of the injected frame, which assured the
QoS TID will not be changed to a different value. Unfortunately,
this workaround complicates the handling of injected frames because
we can't set skb->priority without affecting the TID value in the
QoS field of injected frames.

To avoid this, and to simplify the next patch, detect if a frame is
injected in ieee80211_set_qos_hdr and if so do not change its QoS
field.

Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
Link: https://lore.kernel.org/r/20201104061823.197407-4-Mathy.Vanhoef@kuleuven.be
[fix typos in commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/mac80211/tx.c | 5 +----
net/mac80211/wme.c | 8 ++++++++
2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 56a4d0d20a267..bedb9d85f3d65 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2279,10 +2279,7 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
payload[7]);
}

- /*
- * Initialize skb->priority for QoS frames. This is put in the TID field
- * of the frame before passing it to the driver.
- */
+ /* Initialize skb->priority for QoS frames */
if (ieee80211_is_data_qos(hdr->frame_control)) {
u8 *p = ieee80211_get_qos_ctl(hdr);
skb->priority = *p & IEEE80211_QOS_CTL_TAG1D_MASK;
diff --git a/net/mac80211/wme.c b/net/mac80211/wme.c
index 2fb99325135a0..b74cd9bd5f95e 100644
--- a/net/mac80211/wme.c
+++ b/net/mac80211/wme.c
@@ -249,6 +249,14 @@ void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,

p = ieee80211_get_qos_ctl(hdr);

+ /* don't overwrite the QoS field of injected frames */
+ if (info->flags & IEEE80211_TX_CTL_INJECTED) {
+ /* do take into account Ack policy of injected frames */
+ if (*p & IEEE80211_QOS_CTL_ACK_POLICY_NOACK)
+ info->flags |= IEEE80211_TX_CTL_NO_ACK;
+ return;
+ }
+
/* set up the first byte */

/*
--
2.27.0