mac80211_hwsim: notify wmediumd of used MAC addresses

Currently, wmediumd requires each used MAC address to be configured
as a station in the virtual air, but that doesn't make sense as any
station could have multiple MAC addresses, and even have randomized
ones in scanning, etc.

Add some code here to tell wmediumd of used MAC addresses, binding
them to the hardware address. Combined with a wmediumd patch that
makes it track the addresses this allows configuring just the radio
address (42:00:00:00:nn:00 unless the radio was manually created)
in wmediumd as a station, and all addresses that the station uses
are added/removed dynamically.

Tested with random scan, which without this and the corresponding
wmediumd change doesn't get anything through as the sender doesn't
exist as far as wmediumd is concerned (it's random).

Link: https://lore.kernel.org/r/20200323162358.b397b1a1acef.Ice0536e34e5d96c51f97c374ea8af9551347c7e8@changeid
Signed-off-by: Johannes Berg <[e-mail]>

drivers/net/wireless/mac80211_hwsim.c

···
 	return res;
 }
 
+static void mac80211_hwsim_config_mac_nl(struct ieee80211_hw *hw,
+					 const u8 *addr, bool add)
+{
+	struct mac80211_hwsim_data *data = hw->priv;
+	u32 _portid = READ_ONCE(data->wmediumd);
+	struct sk_buff *skb;
+	void *msg_head;
+
+	if (!_portid && !hwsim_virtio_enabled)
+		return;
+
+	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_ATOMIC);
+	if (!skb)
+		return;
+
+	msg_head = genlmsg_put(skb, 0, 0, &hwsim_genl_family, 0,
+			       add ? HWSIM_CMD_ADD_MAC_ADDR :
+				     HWSIM_CMD_DEL_MAC_ADDR);
+	if (!msg_head) {
+		pr_debug("mac80211_hwsim: problem with msg_head\n");
+		goto nla_put_failure;
+	}
+
+	if (nla_put(skb, HWSIM_ATTR_ADDR_TRANSMITTER,
+		    ETH_ALEN, data->addresses[1].addr))
+		goto nla_put_failure;
+
+	if (nla_put(skb, HWSIM_ATTR_ADDR_RECEIVER, ETH_ALEN, addr))
+		goto nla_put_failure;
+
+	genlmsg_end(skb, msg_head);
+
+	if (hwsim_virtio_enabled)
+		hwsim_tx_virtio(data, skb);
+	else
+		hwsim_unicast_netgroup(data, skb, _portid);
+	return;
+nla_put_failure:
+	nlmsg_free(skb);
+}
+
 static inline u16 trans_tx_rate_flags_ieee2hwsim(struct ieee80211_tx_rate *rate)
 {
 	u16 result = 0;
···
 		  vif->addr);
 	hwsim_set_magic(vif);
 
+	if (vif->type != NL80211_IFTYPE_MONITOR)
+		mac80211_hwsim_config_mac_nl(hw, vif->addr, true);
+
 	vif->cab_queue = 0;
 	vif->hw_queue[IEEE80211_AC_VO] = 0;
 	vif->hw_queue[IEEE80211_AC_VI] = 1;
···
 		  vif->addr);
 	hwsim_check_magic(vif);
 	hwsim_clear_magic(vif);
+	if (vif->type != NL80211_IFTYPE_MONITOR)
+		mac80211_hwsim_config_mac_nl(hw, vif->addr, false);
 }
 
 static void mac80211_hwsim_tx_frame(struct ieee80211_hw *hw,
···
 		hwsim->hw_scan_vif = NULL;
 		hwsim->tmp_chan = NULL;
 		mutex_unlock(&hwsim->mutex);
+		mac80211_hwsim_config_mac_nl(hwsim->hw, hwsim->scan_addr,
+					     false);
 		return;
 	}
 
···
 	memset(hwsim->survey_data, 0, sizeof(hwsim->survey_data));
 	mutex_unlock(&hwsim->mutex);
 
+	mac80211_hwsim_config_mac_nl(hw, hwsim->scan_addr, true);
 	wiphy_dbg(hw->wiphy, "hwsim hw_scan request\n");
 
 	ieee80211_queue_delayed_work(hwsim->hw, &hwsim->hw_scan, 0);
···
 	pr_debug("hwsim sw_scan request, prepping stuff\n");
 
 	memcpy(hwsim->scan_addr, mac_addr, ETH_ALEN);
+	mac80211_hwsim_config_mac_nl(hw, hwsim->scan_addr, true);
 	hwsim->scanning = true;
 	memset(hwsim->survey_data, 0, sizeof(hwsim->survey_data));
 
···
 
 	pr_debug("hwsim sw_scan_complete\n");
 	hwsim->scanning = false;
+	mac80211_hwsim_config_mac_nl(hw, hwsim->scan_addr, false);
 	eth_zero_addr(hwsim->scan_addr);
 
 	mutex_unlock(&hwsim->mutex);

drivers/net/wireless/mac80211_hwsim.h

···
  * @HWSIM_CMD_DEL_RADIO: destroy a radio, reply is multicasted
  * @HWSIM_CMD_GET_RADIO: fetch information about existing radios, uses:
  *	%HWSIM_ATTR_RADIO_ID
+ * @HWSIM_CMD_ADD_MAC_ADDR: add a receive MAC address (given in the
+ *	%HWSIM_ATTR_ADDR_RECEIVER attribute) to a device identified by
+ *	%HWSIM_ATTR_ADDR_TRANSMITTER. This lets wmediumd forward frames
+ *	to this receiver address for a given station.
+ * @HWSIM_CMD_DEL_MAC_ADDR: remove the MAC address again, the attributes
+ *	are the same as to @HWSIM_CMD_ADD_MAC_ADDR.
  * @__HWSIM_CMD_MAX: enum limit
  */
 enum {
···
 	HWSIM_CMD_NEW_RADIO,
 	HWSIM_CMD_DEL_RADIO,
 	HWSIM_CMD_GET_RADIO,
+	HWSIM_CMD_ADD_MAC_ADDR,
+	HWSIM_CMD_DEL_MAC_ADDR,
 	__HWSIM_CMD_MAX,
 };
 #define HWSIM_CMD_MAX (_HWSIM_CMD_MAX - 1)