1 files changed, 82 insertions, 0 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a363ca17bfc5..2d3541c5e058 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -70,6 +70,88 @@ static int get_rdev_dev_by_ifindex(struct net *netns, struct nlattr **attrs,
         return 0;
 }
 
+static struct cfg80211_registered_device *
+__cfg80211_rdev_from_info(struct genl_info *info)
+{
+        int ifindex;
+        struct cfg80211_registered_device *bywiphyidx = NULL, *byifidx = NULL;
+        struct net_device *dev;
+        int err = -EINVAL;
+
+        assert_cfg80211_lock();
+
+        if (info->attrs[NL80211_ATTR_WIPHY]) {
+                bywiphyidx = cfg80211_rdev_by_wiphy_idx(
+                                nla_get_u32(info->attrs[NL80211_ATTR_WIPHY]));
+                err = -ENODEV;
+        }
+
+        if (info->attrs[NL80211_ATTR_IFINDEX]) {
+                ifindex = nla_get_u32(info->attrs[NL80211_ATTR_IFINDEX]);
+                dev = dev_get_by_index(genl_info_net(info), ifindex);
+                if (dev) {
+                        if (dev->ieee80211_ptr)
+                                byifidx =
+                                        wiphy_to_dev(dev->ieee80211_ptr->wiphy);
+                        dev_put(dev);
+                }
+                err = -ENODEV;
+        }
+
+        if (bywiphyidx && byifidx) {
+                if (bywiphyidx != byifidx)
+                        return ERR_PTR(-EINVAL);
+                else
+                        return bywiphyidx; /* == byifidx */
+        }
+        if (bywiphyidx)
+                return bywiphyidx;
+
+        if (byifidx)
+                return byifidx;
+
+        return ERR_PTR(err);
+}
+
+/*
+ * This function returns a pointer to the driver
+ * that the genl_info item that is passed refers to.
+ * If successful, it returns non-NULL and also locks
+ * the driver's mutex!
+ *
+ * This means that you need to call cfg80211_unlock_rdev()
+ * before being allowed to acquire &cfg80211_mutex!
+ *
+ * This is necessary because we need to lock the global
+ * mutex to get an item off the list safely, and then
+ * we lock the rdev mutex so it doesn't go away under us.
+ *
+ * We don't want to keep cfg80211_mutex locked
+ * for all the time in order to allow requests on
+ * other interfaces to go through at the same time.
+ *
+ * The result of this can be a PTR_ERR and hence must
+ * be checked with IS_ERR() for errors.
+ */
+static struct cfg80211_registered_device *
+cfg80211_get_dev_from_info(struct genl_info *info)
+{
+        struct cfg80211_registered_device *rdev;
+
+        mutex_lock(&cfg80211_mutex);
+        rdev = __cfg80211_rdev_from_info(info);
+
+        /* if it is not an error we grab the lock on
+         * it to assure it won't be going away while
+         * we operate on it */
+        if (!IS_ERR(rdev))
+                mutex_lock(&rdev->mtx);
+
+        mutex_unlock(&cfg80211_mutex);
+
+        return rdev;
+}
+
 /* policy for the attributes */
 static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
         [NL80211_ATTR_WIPHY] = { .type = NLA_U32 },