mac80211_hwsim: add permanent mac address option for new radios

If simulation needs predictable permanent mac addresses of hwsim wireless
phy, this patch add the ability to create a new radio with a user defined
permanent mac address. Allowed mac addresses needs to be locally
administrated mac addresses (as also the former fixed 42:* and 02:* were).

To do not break the operation with legacy software using hwsim, the new
address is set twice. The problem here is, the netlink call backs use
wiphy->addresses[1] as identification of a radio and not the proposed
permanent address (wiphy->addresses[0]). This design decision is not
documented in the kernel repo, therefore this patch simply reproduces this,
but with the same address.
Signed-off-by: Benjamin Beichler <benjamin.beichler@uni-rostock.de>
[make pointer const]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/mac80211_hwsim.c

@@ -637,6 +637,7 @@ static const struct nla_policy hwsim_genl_policy[HWSIM_ATTR_MAX + 1] = {
 	[HWSIM_ATTR_RADIO_NAME] = { .type = NLA_STRING },
 	[HWSIM_ATTR_NO_VIF] = { .type = NLA_FLAG },
 	[HWSIM_ATTR_FREQ] = { .type = NLA_U32 },
+	[HWSIM_ATTR_PERM_ADDR] = { .type = NLA_UNSPEC, .len = ETH_ALEN },
 };
 
 static void mac80211_hwsim_tx_frame(struct ieee80211_hw *hw,
@@ -2408,6 +2409,7 @@ struct hwsim_new_radio_params {
 	bool destroy_on_close;
 	const char *hwname;
 	bool no_vif;
+	const u8 *perm_addr;
 };
 
 static void hwsim_mcast_config_msg(struct sk_buff *mcast_skb,
@@ -2572,15 +2574,25 @@ static int mac80211_hwsim_new_radio(struct genl_info *info,
 	skb_queue_head_init(&data->pending);
 
 	SET_IEEE80211_DEV(hw, data->dev);
-	eth_zero_addr(addr);
-	addr[0] = 0x02;
-	addr[3] = idx >> 8;
-	addr[4] = idx;
-	memcpy(data->addresses[0].addr, addr, ETH_ALEN);
-	memcpy(data->addresses[1].addr, addr, ETH_ALEN);
-	data->addresses[1].addr[0] |= 0x40;
-	hw->wiphy->n_addresses = 2;
-	hw->wiphy->addresses = data->addresses;
+	if (!param->perm_addr) {
+		eth_zero_addr(addr);
+		addr[0] = 0x02;
+		addr[3] = idx >> 8;
+		addr[4] = idx;
+		memcpy(data->addresses[0].addr, addr, ETH_ALEN);
+		/* Why need here second address ? */
+		data->addresses[1].addr[0] |= 0x40;
+		memcpy(data->addresses[1].addr, addr, ETH_ALEN);
+		hw->wiphy->n_addresses = 2;
+		hw->wiphy->addresses = data->addresses;
+		/* possible address clash is checked at hash table insertion */
+	} else {
+		memcpy(data->addresses[0].addr, param->perm_addr, ETH_ALEN);
+		/* compatibility with automatically generated mac addr */
+		memcpy(data->addresses[1].addr, param->perm_addr, ETH_ALEN);
+		hw->wiphy->n_addresses = 2;
+		hw->wiphy->addresses = data->addresses;
+	}
 
 	data->channels = param->channels;
 	data->use_chanctx = param->use_chanctx;
@@ -3210,6 +3222,19 @@ static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
 		param.regd = hwsim_world_regdom_custom[idx];
 	}
 
+	if (info->attrs[HWSIM_ATTR_PERM_ADDR]) {
+		if (!is_valid_ether_addr(
+				nla_data(info->attrs[HWSIM_ATTR_PERM_ADDR]))) {
+			GENL_SET_ERR_MSG(info,"MAC is no valid source addr");
+			NL_SET_BAD_ATTR(info->extack,
+					info->attrs[HWSIM_ATTR_PERM_ADDR]);
+			return -EINVAL;
+		}
+
+
+		param.perm_addr = nla_data(info->attrs[HWSIM_ATTR_PERM_ADDR]);
+	}
+
 	ret = mac80211_hwsim_new_radio(info, &param);
 	kfree(hwname);
 	return ret;

drivers/net/wireless/mac80211_hwsim.h

@@ -68,7 +68,12 @@ enum hwsim_tx_control_flags {
  *	%HWSIM_ATTR_SIGNAL, %HWSIM_ATTR_COOKIE
  * @HWSIM_CMD_NEW_RADIO: create a new radio with the given parameters,
  *	returns the radio ID (>= 0) or negative on errors, if successful
- *	then multicast the result
+ *	then multicast the result, uses optional parameter:
+ *	%HWSIM_ATTR_REG_STRICT_REG, %HWSIM_ATTR_SUPPORT_P2P_DEVICE,
+ *	%HWSIM_ATTR_DESTROY_RADIO_ON_CLOSE, %HWSIM_ATTR_CHANNELS,
+ *	%HWSIM_ATTR_NO_VIF, %HWSIM_ATTR_RADIO_NAME, %HWSIM_ATTR_USE_CHANCTX,
+ *	%HWSIM_ATTR_REG_HINT_ALPHA2, %HWSIM_ATTR_REG_CUSTOM_REG,
+ *	%HWSIM_ATTR_PERM_ADDR
  * @HWSIM_CMD_DEL_RADIO: destroy a radio, reply is multicasted
  * @HWSIM_CMD_GET_RADIO: fetch information about existing radios, uses:
  *	%HWSIM_ATTR_RADIO_ID
@@ -126,6 +131,7 @@ enum {
  * @HWSIM_ATTR_FREQ: Frequency at which packet is transmitted or received.
  * @HWSIM_ATTR_TX_INFO_FLAGS: additional flags for corresponding
  *	rates of %HWSIM_ATTR_TX_INFO
+ * @HWSIM_ATTR_PERM_ADDR: permanent mac address of new radio
  * @__HWSIM_ATTR_MAX: enum limit
  */
 
@@ -153,6 +159,7 @@ enum {
 	HWSIM_ATTR_FREQ,
 	HWSIM_ATTR_PAD,
 	HWSIM_ATTR_TX_INFO_FLAGS,
+	HWSIM_ATTR_PERM_ADDR,
 	__HWSIM_ATTR_MAX,
 };
 #define HWSIM_ATTR_MAX (__HWSIM_ATTR_MAX - 1)