mac80211: Disallow concurrent IBSS/STA mode interfaces
Disallow having more than one IBSS interface up at any time
because of beacon distribution issues, and for now also disallow
having more than one IBSS/STA interface up at the same time
because we use the master interface's BSS struct which would
be completely corrupted when we have more than one up.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c
index f82ebdd..2133c9f 100644
--- a/net/mac80211/ieee80211.c
+++ b/net/mac80211/ieee80211.c
@@ -183,8 +183,52 @@
list_for_each_entry(nsdata, &local->interfaces, list) {
struct net_device *ndev = nsdata->dev;
- if (ndev != dev && ndev != local->mdev && netif_running(ndev) &&
- compare_ether_addr(dev->dev_addr, ndev->dev_addr) == 0) {
+ if (ndev != dev && ndev != local->mdev && netif_running(ndev)) {
+ /*
+ * Allow only a single IBSS interface to be up at any
+ * time. This is restricted because beacon distribution
+ * cannot work properly if both are in the same IBSS.
+ *
+ * To remove this restriction we'd have to disallow them
+ * from setting the same SSID on different IBSS interfaces
+ * belonging to the same hardware. Then, however, we're
+ * faced with having to adopt two different TSF timers...
+ */
+ if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS &&
+ nsdata->vif.type == IEEE80211_IF_TYPE_IBSS)
+ return -EBUSY;
+
+ /*
+ * Disallow multiple IBSS/STA mode interfaces.
+ *
+ * This is a technical restriction, it is possible although
+ * most likely not IEEE 802.11 compliant to have multiple
+ * STAs with just a single hardware (the TSF timer will not
+ * be adjusted properly.)
+ *
+ * However, because mac80211 uses the master device's BSS
+ * information for each STA/IBSS interface, doing this will
+ * currently corrupt that BSS information completely, unless,
+ * a not very useful case, both STAs are associated to the
+ * same BSS.
+ *
+ * To remove this restriction, the BSS information needs to
+ * be embedded in the STA/IBSS mode sdata instead of using
+ * the master device's BSS structure.
+ */
+ if ((sdata->vif.type == IEEE80211_IF_TYPE_STA ||
+ sdata->vif.type == IEEE80211_IF_TYPE_IBSS) &&
+ (nsdata->vif.type == IEEE80211_IF_TYPE_STA ||
+ nsdata->vif.type == IEEE80211_IF_TYPE_IBSS))
+ return -EBUSY;
+
+ /*
+ * The remaining checks are only performed for interfaces
+ * with the same MAC address.
+ */
+ if (compare_ether_addr(dev->dev_addr, ndev->dev_addr))
+ continue;
+
/*
* check whether it may have the same address
*/
@@ -196,8 +240,7 @@
* can only add VLANs to enabled APs
*/
if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN &&
- nsdata->vif.type == IEEE80211_IF_TYPE_AP &&
- netif_running(nsdata->dev))
+ nsdata->vif.type == IEEE80211_IF_TYPE_AP)
sdata->u.vlan.ap = nsdata;
}
}