cfg80211: add channel checking for iface combinations

.connect cannot be handled since the driver scans
and connects on its own. It is up to the driver
then to refuse a connection (with -EBUSY for
example).

Non-fixed channel IBSSes always take a single
channel resource. For example two non-fixed
channel IBSSes always take up 2
num_different_channels, even if they operate on
the same channel at a given point of time.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 88 insertions, 8 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 580551e9caba..b26695ad3e97 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -373,6 +373,14 @@ static int wiphy_verify_combinations(struct wiphy *wiphy)
                 if (WARN_ON(!c->num_different_channels))
                         return -EINVAL;
 
+                /*
+                 * Put a sane limit on maximum number of different
+                 * channels to simplify channel accounting code.
+                 */
+                if (WARN_ON(c->num_different_channels >
+                                CFG80211_MAX_NUM_DIFFERENT_CHANNELS))
+                        return -EINVAL;
+
                 if (WARN_ON(!c->n_limits))
                         return -EINVAL;
 
diff --git a/net/wireless/core.h b/net/wireless/core.h
index d5efe1b0a8f7..81fef3ddb5a8 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -428,9 +428,20 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
                           u32 *flags, struct vif_params *params);
 void cfg80211_process_rdev_events(struct cfg80211_registered_device *rdev);
 
-int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
-                                  struct wireless_dev *wdev,
-                                  enum nl80211_iftype iftype);
+int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
+                                 struct wireless_dev *wdev,
+                                 enum nl80211_iftype iftype,
+                                 struct ieee80211_channel *chan,
+                                 enum cfg80211_chan_mode chanmode);
+
+static inline int
+cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
+                              struct wireless_dev *wdev,
+                              enum nl80211_iftype iftype)
+{
+        return cfg80211_can_use_iftype_chan(rdev, wdev, iftype, NULL,
+                                            CHAN_MODE_UNDEFINED);
+}
 
 static inline int
 cfg80211_can_add_interface(struct cfg80211_registered_device *rdev,
@@ -439,6 +450,16 @@ cfg80211_can_add_interface(struct cfg80211_registered_device *rdev,
         return cfg80211_can_change_interface(rdev, NULL, iftype);
 }
 
+static inline int
+cfg80211_can_use_chan(struct cfg80211_registered_device *rdev,
+                      struct wireless_dev *wdev,
+                      struct ieee80211_channel *chan,
+                      enum cfg80211_chan_mode chanmode)
+{
+        return cfg80211_can_use_iftype_chan(rdev, wdev, wdev->iftype,
+                                            chan, chanmode);
+}
+
 void
 cfg80211_get_chan_state(struct cfg80211_registered_device *rdev,
                         struct wireless_dev *wdev,
@@ -461,6 +482,8 @@ int cfg80211_validate_beacon_int(struct cfg80211_registered_device *rdev,
 void cfg80211_update_iface_num(struct cfg80211_registered_device *rdev,
                                enum nl80211_iftype iftype, int num);
 
+#define CFG80211_MAX_NUM_DIFFERENT_CHANNELS 10
+
 #ifdef CONFIG_CFG80211_DEVELOPER_WARNINGS
 #define CFG80211_DEV_WARN_ON(cond)      WARN_ON(cond)
 #else
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 9b92ec57d07b..4713cea9a2fa 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -938,13 +938,20 @@ int cfg80211_validate_beacon_int(struct cfg80211_registered_device *rdev,
         return res;
 }
 
-int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
-                                  struct wireless_dev *wdev,
-                                  enum nl80211_iftype iftype)
+int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
+                                 struct wireless_dev *wdev,
+                                 enum nl80211_iftype iftype,
+                                 struct ieee80211_channel *chan,
+                                 enum cfg80211_chan_mode chanmode)
 {
         struct wireless_dev *wdev_iter;
         u32 used_iftypes = BIT(iftype);
         int num[NUM_NL80211_IFTYPES];
+        struct ieee80211_channel
+                        *used_channels[CFG80211_MAX_NUM_DIFFERENT_CHANNELS];
+        struct ieee80211_channel *ch;
+        enum cfg80211_chan_mode chmode;
+        int num_different_channels = 0;
         int total = 1;
         int i, j;
 
@@ -955,9 +962,23 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
                 return 0;
 
         memset(num, 0, sizeof(num));
+        memset(used_channels, 0, sizeof(used_channels));
 
         num[iftype] = 1;
 
+        switch (chanmode) {
+        case CHAN_MODE_UNDEFINED:
+                break;
+        case CHAN_MODE_SHARED:
+                WARN_ON(!chan);
+                used_channels[0] = chan;
+                num_different_channels++;
+                break;
+        case CHAN_MODE_EXCLUSIVE:
+                num_different_channels++;
+                break;
+        }
+
         mutex_lock(&rdev->devlist_mtx);
         list_for_each_entry(wdev_iter, &rdev->netdev_list, list) {
                 if (wdev_iter == wdev)
@@ -968,6 +989,31 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
                 if (rdev->wiphy.software_iftypes & BIT(wdev_iter->iftype))
                         continue;
 
+                cfg80211_get_chan_state(rdev, wdev_iter, &ch, &chmode);
+
+                switch (chmode) {
+                case CHAN_MODE_UNDEFINED:
+                        break;
+                case CHAN_MODE_SHARED:
+                        for (i = 0; i < CFG80211_MAX_NUM_DIFFERENT_CHANNELS; i++)
+                                if (!used_channels[i] || used_channels[i] == ch)
+                                        break;
+
+                        if (i == CFG80211_MAX_NUM_DIFFERENT_CHANNELS) {
+                                mutex_unlock(&rdev->devlist_mtx);
+                                return -EBUSY;
+                        }
+
+                        if (used_channels[i] == NULL) {
+                                used_channels[i] = ch;
+                                num_different_channels++;
+                        }
+                        break;
+                case CHAN_MODE_EXCLUSIVE:
+                        num_different_channels++;
+                        break;
+                }
+
                 num[wdev_iter->iftype]++;
                 total++;
                 used_iftypes |= BIT(wdev_iter->iftype);
@@ -984,12 +1030,15 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
 
                 c = &rdev->wiphy.iface_combinations[i];
 
+                if (total > c->max_interfaces)
+                        continue;
+                if (num_different_channels > c->num_different_channels)
+                        continue;
+
                 limits = kmemdup(c->limits, sizeof(limits[0]) * c->n_limits,
                                  GFP_KERNEL);
                 if (!limits)
                         return -ENOMEM;
-                if (total > c->max_interfaces)
-                        goto cont;
 
                 for (iftype = 0; iftype < NUM_NL80211_IFTYPES; iftype++) {
                         if (rdev->wiphy.software_iftypes & BIT(iftype))