Commit 665e8aaf authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
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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: default avatarJohannes Berg <>
Signed-off-by: default avatarJohn W. Linville <>
parent 43ba7e95
......@@ -183,8 +183,52 @@ static int ieee80211_open(struct net_device *dev)
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))
* check whether it may have the same address
......@@ -196,8 +240,7 @@ static int ieee80211_open(struct net_device *dev)
* can only add VLANs to enabled APs
if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN &&
nsdata->vif.type == IEEE80211_IF_TYPE_AP &&
nsdata->vif.type == IEEE80211_IF_TYPE_AP)
sdata->u.vlan.ap = nsdata;
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