From 665e8aafb4e0826caec9db25617b186ea3f3ec91 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 21 Feb 2008 01:10:07 +0100 Subject: [PATCH] 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 Signed-off-by: John W. Linville --- net/mac80211/ieee80211.c | 51 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 47 insertions(+), 4 deletions(-) diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c index f82ebdd53d48..2133c9fd27a4 100644 --- a/net/mac80211/ieee80211.c +++ b/net/mac80211/ieee80211.c @@ -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)) + continue; + /* * 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 && - netif_running(nsdata->dev)) + nsdata->vif.type == IEEE80211_IF_TYPE_AP) sdata->u.vlan.ap = nsdata; } } -- 2.20.1