cfg80211: advertise possible interface combinations

Add the ability to advertise interface combinations in nl80211.
This allows the driver to indicate what the combinations are
that it supports. "Combinations" of just a single interface are
implicit, as previously. Note that cfg80211 will enforce that
the restrictions are met, but not for all drivers yet (once all
drivers are updated, we can remove the flag and enforce for all).

When no combinations are actually supported, an empty list will
be exported so that userspace can know if the kernel exported
this info or not (although it isn't clear to me what tools using
the info should do if the kernel didn't export it).

Since some interface types are purely virtual/software and don't
fit the restrictions, those are exposed in a new list of pure SW
types, not subject to restrictions. This mainly exists to handle
AP-VLAN and monitor interfaces in mac80211.

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

1 files changed, 69 insertions, 0 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 18b002f16860..c22ef3492ee6 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -416,6 +416,67 @@ struct wiphy *wiphy_new(const struct cfg80211_ops *ops, int sizeof_priv)
 }
 EXPORT_SYMBOL(wiphy_new);
 
+static int wiphy_verify_combinations(struct wiphy *wiphy)
+{
+        const struct ieee80211_iface_combination *c;
+        int i, j;
+
+        /* If we have combinations enforce them */
+        if (wiphy->n_iface_combinations)
+                wiphy->flags |= WIPHY_FLAG_ENFORCE_COMBINATIONS;
+
+        for (i = 0; i < wiphy->n_iface_combinations; i++) {
+                u32 cnt = 0;
+                u16 all_iftypes = 0;
+
+                c = &wiphy->iface_combinations[i];
+
+                /* Combinations with just one interface aren't real */
+                if (WARN_ON(c->max_interfaces < 2))
+                        return -EINVAL;
+
+                /* Need at least one channel */
+                if (WARN_ON(!c->num_different_channels))
+                        return -EINVAL;
+
+                if (WARN_ON(!c->n_limits))
+                        return -EINVAL;
+
+                for (j = 0; j < c->n_limits; j++) {
+                        u16 types = c->limits[j].types;
+
+                        /*
+                         * interface types shouldn't overlap, this is
+                         * used in cfg80211_can_change_interface()
+                         */
+                        if (WARN_ON(types & all_iftypes))
+                                return -EINVAL;
+                        all_iftypes |= types;
+
+                        if (WARN_ON(!c->limits[j].max))
+                                return -EINVAL;
+
+                        /* Shouldn't list software iftypes in combinations! */
+                        if (WARN_ON(wiphy->software_iftypes & types))
+                                return -EINVAL;
+
+                        cnt += c->limits[j].max;
+                        /*
+                         * Don't advertise an unsupported type
+                         * in a combination.
+                         */
+                        if (WARN_ON((wiphy->interface_modes & types) != types))
+                                return -EINVAL;
+                }
+
+                /* You can't even choose that many! */
+                if (WARN_ON(cnt < c->max_interfaces))
+                        return -EINVAL;
+        }
+
+        return 0;
+}
+
 int wiphy_register(struct wiphy *wiphy)
 {
         struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
@@ -444,6 +505,10 @@ int wiphy_register(struct wiphy *wiphy)
         if (WARN_ON(ifmodes != wiphy->interface_modes))
                 wiphy->interface_modes = ifmodes;
 
+        res = wiphy_verify_combinations(wiphy);
+        if (res)
+                return res;
+
         /* sanity check supported bands/channels */
         for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
                 sband = wiphy->bands[band];
@@ -698,6 +763,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
         struct net_device *dev = ndev;
         struct wireless_dev *wdev = dev->ieee80211_ptr;
         struct cfg80211_registered_device *rdev;
+        int ret;
 
         if (!wdev)
                 return NOTIFY_DONE;
@@ -893,6 +959,9 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
                         return notifier_from_errno(-EOPNOTSUPP);
                 if (rfkill_blocked(rdev->rfkill))
                         return notifier_from_errno(-ERFKILL);
+                ret = cfg80211_can_add_interface(rdev, wdev->iftype);
+                if (ret)
+                        return notifier_from_errno(ret);
                 break;
         }