mac80211: allow AP_VLAN operation on crypto controlled devices

In the current implementation, mac80211 advertises the support of
AP_VLANs based on the driver's support for AP mode; it also
blocks encrypted AP_VLAN operation on devices advertising
SW_CRYPTO_CONTROL.

The implementation seems weird in it's current form and could be
often confusing, this is because there can be drivers advertising
both SW_CRYPTO_CONTROL and AP mode support (ex: ath10k) in which case
AP_VLAN will still be supported but only in open BSS and not in
secured BSS.

When SW_CRYPTO_CONTROL is enabled, it makes more sense if the decision
to support AP_VLANs is left to the driver. Mac80211 can then allow
AP_VLAN operations depending on the driver support.

Signed-off-by: Manikanta Pubbisetty <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/key.c

···
 
 static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
 {
-	struct ieee80211_sub_if_data *sdata;
+	struct ieee80211_sub_if_data *sdata = key->sdata;
 	struct sta_info *sta;
 	int ret = -EOPNOTSUPP;
 
···
 	if (sta && !sta->uploaded)
 		goto out_unsupported;
 
-	sdata = key->sdata;
 	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
 		/*
 		 * The driver doesn't know anything about VLAN interfaces.
···
 		/* all of these we can do in software - if driver can */
 		if (ret == 1)
 			return 0;
-		if (ieee80211_hw_check(&key->local->hw, SW_CRYPTO_CONTROL))
+		if (ieee80211_hw_check(&key->local->hw, SW_CRYPTO_CONTROL)) {
+			if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+				return 0;
 			return -EINVAL;
+		}
 		return 0;
 	default:
 		return -EINVAL;

net/mac80211/main.c

···
 			             IEEE80211_HT_CAP_SM_PS_SHIFT;
 	}
 
-	/* if low-level driver supports AP, we also support VLAN */
-	if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_AP)) {
+	/* if low-level driver supports AP, we also support VLAN.
+	 * drivers advertising SW_CRYPTO_CONTROL should enable AP_VLAN
+	 * based on their support to transmit SW encrypted packets.
+	 */
+	if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_AP) &&
+	    !ieee80211_hw_check(&local->hw, SW_CRYPTO_CONTROL)) {
 		hw->wiphy->interface_modes |= BIT(NL80211_IFTYPE_AP_VLAN);
 		hw->wiphy->software_iftypes |= BIT(NL80211_IFTYPE_AP_VLAN);
 	}