mac80211: Fixed BSSID handling revisited

This patch cleanup the fixed BSSID handling, that
ieee80211_sta_set_bssid() works like ieee80211_sta_set_ssid(). So
that the BSSID is only a second selection criterion besides the
SSID. This allows us to create new IBSS networks with fixed BSSIDs,
which was broken before.

In the second version of this patch the handling of the stupid merges
to the same BSSID is moved out to get reworked into an other patch.

And this version hopefully solves the problems with some low-level
drivers and re-adds the config BSSID warning to help debugging the
low-level drivers.

Much thanks to all who have helped testing! :)
Signed-off-by: Alina Friedrichsen <x-alina@gmx.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/mlme.c

@@ -1615,6 +1615,7 @@ static int ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
 
 	ieee80211_sta_def_wmm_params(sdata, bss);
 
+	ifsta->flags |= IEEE80211_STA_PREV_BSSID_SET;
 	ifsta->state = IEEE80211_STA_MLME_IBSS_JOINED;
 	mod_timer(&ifsta->timer, jiffies + IEEE80211_IBSS_MERGE_INTERVAL);
 
@@ -2178,19 +2179,18 @@ static int ieee80211_sta_create_ibss(struct ieee80211_sub_if_data *sdata,
 	int i;
 	int ret;
 
-#if 0
-	/* Easier testing, use fixed BSSID. */
-	memset(bssid, 0xfe, ETH_ALEN);
-#else
-	/* Generate random, not broadcast, locally administered BSSID. Mix in
-	 * own MAC address to make sure that devices that do not have proper
-	 * random number generator get different BSSID. */
-	get_random_bytes(bssid, ETH_ALEN);
-	for (i = 0; i < ETH_ALEN; i++)
-		bssid[i] ^= sdata->dev->dev_addr[i];
-	bssid[0] &= ~0x01;
-	bssid[0] |= 0x02;
-#endif
+	if (sdata->u.sta.flags & IEEE80211_STA_BSSID_SET) {
+		memcpy(bssid, ifsta->bssid, ETH_ALEN);
+	} else {
+		/* Generate random, not broadcast, locally administered BSSID. Mix in
+		 * own MAC address to make sure that devices that do not have proper
+		 * random number generator get different BSSID. */
+		get_random_bytes(bssid, ETH_ALEN);
+		for (i = 0; i < ETH_ALEN; i++)
+			bssid[i] ^= sdata->dev->dev_addr[i];
+		bssid[0] &= ~0x01;
+		bssid[0] |= 0x02;
+	}
 
 	printk(KERN_DEBUG "%s: Creating new IBSS network, BSSID %pM\n",
 	       sdata->dev->name, bssid);
@@ -2251,6 +2251,9 @@ static int ieee80211_sta_find_ibss(struct ieee80211_sub_if_data *sdata,
 		    memcmp(ifsta->ssid, bss->ssid, bss->ssid_len) != 0
 		    || !(bss->capability & WLAN_CAPABILITY_IBSS))
 			continue;
+		if ((ifsta->flags & IEEE80211_STA_BSSID_SET) &&
+		    memcmp(ifsta->bssid, bss->bssid, ETH_ALEN) != 0)
+			continue;
 #ifdef CONFIG_MAC80211_IBSS_DEBUG
 		printk(KERN_DEBUG "   bssid=%pM found\n", bss->bssid);
 #endif /* CONFIG_MAC80211_IBSS_DEBUG */
@@ -2267,7 +2270,9 @@ static int ieee80211_sta_find_ibss(struct ieee80211_sub_if_data *sdata,
 		       "%pM\n", bssid, ifsta->bssid);
 #endif /* CONFIG_MAC80211_IBSS_DEBUG */
 
-	if (found && memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0) {
+	if (found &&
+	    ((!(ifsta->flags & IEEE80211_STA_PREV_BSSID_SET)) ||
+	     memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0)) {
 		int ret;
 		int search_freq;
 
@@ -2605,16 +2610,16 @@ int ieee80211_sta_set_ssid(struct ieee80211_sub_if_data *sdata, char *ssid, size
 		memset(ifsta->ssid, 0, sizeof(ifsta->ssid));
 		memcpy(ifsta->ssid, ssid, len);
 		ifsta->ssid_len = len;
-		ifsta->flags &= ~IEEE80211_STA_PREV_BSSID_SET;
 	}
 
+	ifsta->flags &= ~IEEE80211_STA_PREV_BSSID_SET;
+
 	if (len)
 		ifsta->flags |= IEEE80211_STA_SSID_SET;
 	else
 		ifsta->flags &= ~IEEE80211_STA_SSID_SET;
 
-	if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
-	    !(ifsta->flags & IEEE80211_STA_BSSID_SET)) {
+	if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
 		ifsta->ibss_join_req = jiffies;
 		ifsta->state = IEEE80211_STA_MLME_IBSS_SEARCH;
 		return ieee80211_sta_find_ibss(sdata, ifsta);
@@ -2634,36 +2639,25 @@ int ieee80211_sta_get_ssid(struct ieee80211_sub_if_data *sdata, char *ssid, size
 int ieee80211_sta_set_bssid(struct ieee80211_sub_if_data *sdata, u8 *bssid)
 {
 	struct ieee80211_if_sta *ifsta;
-	int res;
-	bool valid;
 
 	ifsta = &sdata->u.sta;
-	valid = is_valid_ether_addr(bssid);
 
-	if (memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0) {
-		if(valid)
-			memcpy(ifsta->bssid, bssid, ETH_ALEN);
-		else
-			memset(ifsta->bssid, 0, ETH_ALEN);
-		res = 0;
-		/*
-		 * Hack! See also ieee80211_sta_set_ssid.
-		 */
-		if (netif_running(sdata->dev))
-			res = ieee80211_if_config(sdata, IEEE80211_IFCC_BSSID);
-		if (res) {
+	if (is_valid_ether_addr(bssid)) {
+		memcpy(ifsta->bssid, bssid, ETH_ALEN);
+		ifsta->flags |= IEEE80211_STA_BSSID_SET;
+	} else {
+		memset(ifsta->bssid, 0, ETH_ALEN);
+		ifsta->flags &= ~IEEE80211_STA_BSSID_SET;
+	}
+
+	if (netif_running(sdata->dev)) {
+		if (ieee80211_if_config(sdata, IEEE80211_IFCC_BSSID)) {
 			printk(KERN_DEBUG "%s: Failed to config new BSSID to "
 			       "the low-level driver\n", sdata->dev->name);
-			return res;
 		}
 	}
 
-	if (valid)
-		ifsta->flags |= IEEE80211_STA_BSSID_SET;
-	else
-		ifsta->flags &= ~IEEE80211_STA_BSSID_SET;
-
-	return 0;
+	return ieee80211_sta_set_ssid(sdata, ifsta->ssid, ifsta->ssid_len);
 }
 
 int ieee80211_sta_set_extra_ie(struct ieee80211_sub_if_data *sdata, char *ie, size_t len)