wifi: cfg80211: make cluster id an array

cfg80211_nan_conf::cluster_id is currently a pointer, but there is no real
reason to not have it an array. It makes things easier as there is no
need to check the pointer validity each time.
If a cluster ID wasn't provided by user space it will be randomized.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20260302091108.2b12e4ccf5bb.Ib16bf5cca55463d4c89e18099cf1dfe4de95d405@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

5 files changed, 17 insertions, 19 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/mld/nan.c b/drivers/net/wireless/intel/iwlwifi/mld/nan.c
index 2dbd3d58b0c6..4d8e85f2bd7c 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/nan.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/nan.c
@@ -54,9 +54,8 @@ static int iwl_mld_nan_config(struct iwl_mld *mld,
 	ether_addr_copy(cmd.nmi_addr, vif->addr);
 	cmd.master_pref = conf->master_pref;
 
-	if (conf->cluster_id)
-		memcpy(cmd.cluster_id, conf->cluster_id + 4,
-		       sizeof(cmd.cluster_id));
+	memcpy(cmd.cluster_id, conf->cluster_id + 4,
+	       sizeof(cmd.cluster_id));
 
 	cmd.scan_period = conf->scan_period < 255 ? conf->scan_period : 255;
 	cmd.dwell_time =
diff --git a/drivers/net/wireless/virtual/mac80211_hwsim.c b/drivers/net/wireless/virtual/mac80211_hwsim.c
index c6871c6c771a..475918ee8132 100644
--- a/drivers/net/wireless/virtual/mac80211_hwsim.c
+++ b/drivers/net/wireless/virtual/mac80211_hwsim.c
@@ -4151,7 +4151,7 @@ static int mac80211_hwsim_start_nan(struct ieee80211_hw *hw,
 		      ns_to_ktime(until_dw * NSEC_PER_USEC),
 		      HRTIMER_MODE_REL_SOFT);
 
-	if (conf->cluster_id && !is_zero_ether_addr(conf->cluster_id) &&
+	if (!is_zero_ether_addr(conf->cluster_id) &&
 	    is_zero_ether_addr(hwsim_nan_cluster_id)) {
 		memcpy(hwsim_nan_cluster_id, conf->cluster_id, ETH_ALEN);
 	} else if (is_zero_ether_addr(hwsim_nan_cluster_id)) {
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index c21354647da0..8a63dea500ad 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -4023,7 +4023,6 @@ struct cfg80211_nan_band_config {
  *	(i.e. BIT(NL80211_BAND_2GHZ)).
  * @cluster_id: cluster ID used for NAN synchronization. This is a MAC address
  *	that can take a value from 50-6F-9A-01-00-00 to 50-6F-9A-01-FF-FF.
- *	If NULL, the device will pick a random Cluster ID.
  * @scan_period: period (in seconds) between NAN scans.
  * @scan_dwell_time: dwell time (in milliseconds) for NAN scans.
  * @discovery_beacon_interval: interval (in TUs) for discovery beacons.
@@ -4039,7 +4038,7 @@ struct cfg80211_nan_band_config {
 struct cfg80211_nan_conf {
 	u8 master_pref;
 	u8 bands;
-	const u8 *cluster_id;
+	u8 cluster_id[ETH_ALEN] __aligned(2);
 	u16 scan_period;
 	u16 scan_dwell_time;
 	u8 discovery_beacon_interval;
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index aa3b86644e8f..0c4979526c91 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -330,7 +330,6 @@ static void ieee80211_stop_p2p_device(struct wiphy *wiphy,
 
 static void ieee80211_nan_conf_free(struct cfg80211_nan_conf *conf)
 {
-	kfree(conf->cluster_id);
 	kfree(conf->extra_nan_attrs);
 	kfree(conf->vendor_elems);
 	memset(conf, 0, sizeof(*conf));
@@ -372,9 +371,6 @@ static int ieee80211_nan_conf_copy(struct cfg80211_nan_conf *dst,
 		memcpy(&dst->band_cfgs, &src->band_cfgs,
 		       sizeof(dst->band_cfgs));
 
-		kfree(dst->cluster_id);
-		dst->cluster_id = NULL;
-
 		kfree(dst->extra_nan_attrs);
 		dst->extra_nan_attrs = NULL;
 		dst->extra_nan_attrs_len = 0;
@@ -383,12 +379,8 @@ static int ieee80211_nan_conf_copy(struct cfg80211_nan_conf *dst,
 		dst->vendor_elems = NULL;
 		dst->vendor_elems_len = 0;
 
-		if (src->cluster_id) {
-			dst->cluster_id = kmemdup(src->cluster_id, ETH_ALEN,
-						  GFP_KERNEL);
-			if (!dst->cluster_id)
-				goto no_mem;
-		}
+		if (is_zero_ether_addr(dst->cluster_id))
+			ether_addr_copy(dst->cluster_id, src->cluster_id);
 
 		if (src->extra_nan_attrs && src->extra_nan_attrs_len) {
 			dst->extra_nan_attrs = kmemdup(src->extra_nan_attrs,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index de7956dbe0a0..26cf29c8867b 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -21,6 +21,7 @@
 #include <linux/nospec.h>
 #include <linux/etherdevice.h>
 #include <linux/if_vlan.h>
+#include <linux/random.h>
 #include <net/net_namespace.h>
 #include <net/genetlink.h>
 #include <net/cfg80211.h>
@@ -15767,9 +15768,16 @@ static int nl80211_parse_nan_conf(struct wiphy *wiphy,
 		return err;
 
 	changed |= CFG80211_NAN_CONF_CHANGED_CONFIG;
-	if (attrs[NL80211_NAN_CONF_CLUSTER_ID] && start)
-		conf->cluster_id =
-			nla_data(attrs[NL80211_NAN_CONF_CLUSTER_ID]);
+	if (attrs[NL80211_NAN_CONF_CLUSTER_ID] && start) {
+		ether_addr_copy(conf->cluster_id,
+				nla_data(attrs[NL80211_NAN_CONF_CLUSTER_ID]));
+	} else if (start) {
+		conf->cluster_id[0] = 0x50;
+		conf->cluster_id[1] = 0x6f;
+		conf->cluster_id[2] = 0x9a;
+		conf->cluster_id[3] = 0x01;
+		get_random_bytes(&conf->cluster_id[4], 2);
+	}
 
 	if (attrs[NL80211_NAN_CONF_EXTRA_ATTRS]) {
 		conf->extra_nan_attrs =