netdev - [PATCH 6.1 1/2] wifi: mac80211: Allow NSS change only up to capability

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Message-ID: <20240729225956.1352362-1-hauke@hauke-m.de>
Date: Tue, 30 Jul 2024 00:59:55 +0200
From: Hauke Mehrtens <hauke@...ke-m.de>
To: stable@...r.kernel.org
Cc: johannes@...solutions.net,
	linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org,
	quic_ramess@...cinc.com,
	Johannes Berg <johannes.berg@...el.com>,
	Hauke Mehrtens <hauke@...ke-m.de>
Subject: [PATCH 6.1 1/2] wifi: mac80211: Allow NSS change only up to capability

From: Rameshkumar Sundaram <quic_ramess@...cinc.com>

[ Upstream commit 57b341e9ab13e5688491bfd54f8b5502416c8905 ]

Stations can update bandwidth/NSS change in
VHT action frame with action type Operating Mode Notification.
(IEEE Std 802.11-2020 - 9.4.1.53 Operating Mode field)

For Operating Mode Notification, an RX NSS change to a value
greater than AP's maximum NSS should not be allowed.
During fuzz testing, by forcefully sending VHT Op. mode notif.
frames from STA with random rx_nss values, it is found that AP
accepts rx_nss values greater that APs maximum NSS instead of
discarding such NSS change.

Hence allow NSS change only up to maximum NSS that is negotiated
and capped to AP's capability during association.

Signed-off-by: Rameshkumar Sundaram <quic_ramess@...cinc.com>
Link: https://lore.kernel.org/r/20230207114146.10567-1-quic_ramess@quicinc.com
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Hauke Mehrtens <hauke@...ke-m.de>
---
 net/mac80211/vht.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/net/mac80211/vht.c b/net/mac80211/vht.c
index f7526be8a1c7..b3a5c3e96a72 100644
--- a/net/mac80211/vht.c
+++ b/net/mac80211/vht.c
@@ -637,7 +637,7 @@ u32 __ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
 	enum ieee80211_sta_rx_bandwidth new_bw;
 	struct sta_opmode_info sta_opmode = {};
 	u32 changed = 0;
-	u8 nss;
+	u8 nss, cur_nss;
 
 	/* ignore - no support for BF yet */
 	if (opmode & IEEE80211_OPMODE_NOTIF_RX_NSS_TYPE_BF)
@@ -648,10 +648,25 @@ u32 __ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
 	nss += 1;
 
 	if (link_sta->pub->rx_nss != nss) {
-		link_sta->pub->rx_nss = nss;
-		sta_opmode.rx_nss = nss;
-		changed |= IEEE80211_RC_NSS_CHANGED;
-		sta_opmode.changed |= STA_OPMODE_N_SS_CHANGED;
+		cur_nss = link_sta->pub->rx_nss;
+		/* Reset rx_nss and call ieee80211_sta_set_rx_nss() which
+		 * will set the same to max nss value calculated based on capability.
+		 */
+		link_sta->pub->rx_nss = 0;
+		ieee80211_sta_set_rx_nss(link_sta);
+		/* Do not allow an nss change to rx_nss greater than max_nss
+		 * negotiated and capped to APs capability during association.
+		 */
+		if (nss <= link_sta->pub->rx_nss) {
+			link_sta->pub->rx_nss = nss;
+			sta_opmode.rx_nss = nss;
+			changed |= IEEE80211_RC_NSS_CHANGED;
+			sta_opmode.changed |= STA_OPMODE_N_SS_CHANGED;
+		} else {
+			link_sta->pub->rx_nss = cur_nss;
+			pr_warn_ratelimited("Ignoring NSS change in VHT Operating Mode Notification from %pM with invalid nss %d",
+					    link_sta->pub->addr, nss);
+		}
 	}
 
 	switch (opmode & IEEE80211_OPMODE_NOTIF_CHANWIDTH_MASK) {
-- 
2.45.2