wifi: mac80211: don't drop all unprotected public action frames

Not all public action frames have a protected variant. When MFP is
enabled drop only public action frames that have a dual protected
variant.

Fixes: 76a3059 ("wifi: mac80211: drop some unprotected action frames")
Signed-off-by: Avraham Stern <[email protected]>
Signed-off-by: Gregory Greenman <[email protected]>
Link: https://lore.kernel.org/r/20231016145213.2973e3c8d3bb.I6198b8d3b04cf4a97b06660d346caec3032f232a@changeid
Signed-off-by: Johannes Berg <[email protected]>

Author: AviStern

include/linux/ieee80211.h

@@ -4355,6 +4355,35 @@ static inline bool ieee80211_is_public_action(struct ieee80211_hdr *hdr,
 	return mgmt->u.action.category == WLAN_CATEGORY_PUBLIC;
 }
 
+/**
+ * ieee80211_is_protected_dual_of_public_action - check if skb contains a
+ * protected dual of public action management frame
+ * @skb: the skb containing the frame, length will be checked
+ *
+ * Return: true if the skb contains a protected dual of public action
+ * management frame, false otherwise.
+ */
+static inline bool
+ieee80211_is_protected_dual_of_public_action(struct sk_buff *skb)
+{
+	u8 action;
+
+	if (!ieee80211_is_public_action((void *)skb->data, skb->len) ||
+	    skb->len < IEEE80211_MIN_ACTION_SIZE + 1)
+		return false;
+
+	action = *(u8 *)(skb->data + IEEE80211_MIN_ACTION_SIZE);
+
+	return action != WLAN_PUB_ACTION_20_40_BSS_COEX &&
+		action != WLAN_PUB_ACTION_DSE_REG_LOC_ANN &&
+		action != WLAN_PUB_ACTION_MSMT_PILOT &&
+		action != WLAN_PUB_ACTION_TDLS_DISCOVER_RES &&
+		action != WLAN_PUB_ACTION_LOC_TRACK_NOTI &&
+		action != WLAN_PUB_ACTION_FTM_REQUEST &&
+		action != WLAN_PUB_ACTION_FTM_RESPONSE &&
+		action != WLAN_PUB_ACTION_FILS_DISCOVERY;
+}
+
 /**
  * _ieee80211_is_group_privacy_action - check if frame is a group addressed
  * privacy action frame

net/mac80211/rx.c

@@ -2468,8 +2468,7 @@ static int ieee80211_drop_unencrypted_mgmt(struct ieee80211_rx_data *rx)
 
 		/* drop unicast public action frames when using MPF */
 		if (is_unicast_ether_addr(mgmt->da) &&
-		    ieee80211_is_public_action((void *)rx->skb->data,
-					       rx->skb->len))
+		    ieee80211_is_protected_dual_of_public_action(rx->skb))
 			return -EACCES;
 	}