cfg80211: introduce capability for 4addr mode

It's very likely that not many devices will support
four-address mode in station or AP mode so introduce
capability bits for both modes, set them in mac80211
and check them when userspace tries to use the mode.
Also, keep track of 4addr in cfg80211 (wireless_dev)
and not in mac80211 any more. mac80211 can also be
improved for the VLAN case by not looking at the
4addr flag but maintaining the station pointer for
it correctly. However, keep track of use_4addr for
station mode in mac80211 to avoid all the derefs.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 33 insertions, 1 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 6634188f9453..b7b0f67b0c61 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -968,6 +968,28 @@ static int parse_monitor_flags(struct nlattr *nla, u32 *mntrflags)
         return 0;
 }
 
+static int nl80211_valid_4addr(struct cfg80211_registered_device *rdev,
+                               u8 use_4addr, enum nl80211_iftype iftype)
+{
+        if (!use_4addr)
+                return 0;
+
+        switch (iftype) {
+        case NL80211_IFTYPE_AP_VLAN:
+                if (rdev->wiphy.flags & WIPHY_FLAG_4ADDR_AP)
+                        return 0;
+                break;
+        case NL80211_IFTYPE_STATION:
+                if (rdev->wiphy.flags & WIPHY_FLAG_4ADDR_STATION)
+                        return 0;
+                break;
+        default:
+                break;
+        }
+
+        return -EOPNOTSUPP;
+}
+
 static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
 {
         struct cfg80211_registered_device *rdev;
@@ -1011,6 +1033,9 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
         if (info->attrs[NL80211_ATTR_4ADDR]) {
                 params.use_4addr = !!nla_get_u8(info->attrs[NL80211_ATTR_4ADDR]);
                 change = true;
+                err = nl80211_valid_4addr(rdev, params.use_4addr, ntype);
+                if (err)
+                        goto unlock;
         } else {
                 params.use_4addr = -1;
         }
@@ -1034,6 +1059,9 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
         else
                 err = 0;
 
+        if (!err && params.use_4addr != -1)
+                dev->ieee80211_ptr->use_4addr = params.use_4addr;
+
  unlock:
         dev_put(dev);
         cfg80211_unlock_rdev(rdev);
@@ -1081,8 +1109,12 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
                 params.mesh_id_len = nla_len(info->attrs[NL80211_ATTR_MESH_ID]);
         }
 
-        if (info->attrs[NL80211_ATTR_4ADDR])
+        if (info->attrs[NL80211_ATTR_4ADDR]) {
                 params.use_4addr = !!nla_get_u8(info->attrs[NL80211_ATTR_4ADDR]);
+                err = nl80211_valid_4addr(rdev, params.use_4addr, type);
+                if (err)
+                        goto unlock;
+        }
 
         err = parse_monitor_flags(type == NL80211_IFTYPE_MONITOR ?
                                   info->attrs[NL80211_ATTR_MNTR_FLAGS] : NULL,