cfg80211: always notify userspace of new wireless netdevs

This change alters the semantics of NL80211_CMD_NEW_INTERFACE events
by always sending this event whenever a new net_device object
associated with a wdev is registered.  Prior to this change, this event
was only sent as a result of NL80211_CMD_NEW_INTERFACE command sent
from userspace.  This allows userspace to reliably detect new wireless
interfaces (e.g. due to hardware hot-plug events, etc).

For wdevs created without an associated net_device object (e.g.
NL80211_IFTYPE_P2P_DEVICE), the NL80211_CMD_NEW_INTERFACE event is
still generated inside the relevant nl80211 command handler.

Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 37 insertions, 14 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 7645e97362c0..7758c0fe781a 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1079,6 +1079,8 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
                      wdev->iftype == NL80211_IFTYPE_P2P_CLIENT ||
                      wdev->iftype == NL80211_IFTYPE_ADHOC) && !wdev->use_4addr)
                         dev->priv_flags |= IFF_DONT_BRIDGE;
+
+                nl80211_notify_iface(rdev, wdev, NL80211_CMD_NEW_INTERFACE);
                 break;
         case NETDEV_GOING_DOWN:
                 cfg80211_leave(rdev, wdev);
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index f02653a08993..a8c062dbd51d 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2751,7 +2751,7 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
         struct cfg80211_registered_device *rdev = info->user_ptr[0];
         struct vif_params params;
         struct wireless_dev *wdev;
-        struct sk_buff *msg, *event;
+        struct sk_buff *msg;
         int err;
         enum nl80211_iftype type = NL80211_IFTYPE_UNSPECIFIED;
         u32 flags;
@@ -2855,20 +2855,15 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
                 return -ENOBUFS;
         }
 
-        event = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
-        if (event) {
-                if (nl80211_send_iface(event, 0, 0, 0,
-                                       rdev, wdev, false) < 0) {
-                        nlmsg_free(event);
-                        goto out;
-                }
-
-                genlmsg_multicast_netns(&nl80211_fam, wiphy_net(&rdev->wiphy),
-                                        event, 0, NL80211_MCGRP_CONFIG,
-                                        GFP_KERNEL);
-        }
+        /*
+         * For wdevs which have no associated netdev object (e.g. of type
+         * NL80211_IFTYPE_P2P_DEVICE), emit the NEW_INTERFACE event here.
+         * For all other types, the event will be generated from the
+         * netdev notifier
+         */
+        if (!wdev->netdev)
+                nl80211_notify_iface(rdev, wdev, NL80211_CMD_NEW_INTERFACE);
 
-out:
         return genlmsg_reply(msg, info);
 }
 
@@ -11847,6 +11842,29 @@ void nl80211_notify_wiphy(struct cfg80211_registered_device *rdev,
                                 NL80211_MCGRP_CONFIG, GFP_KERNEL);
 }
 
+void nl80211_notify_iface(struct cfg80211_registered_device *rdev,
+                                struct wireless_dev *wdev,
+                                enum nl80211_commands cmd)
+{
+        struct sk_buff *msg;
+
+        WARN_ON(cmd != NL80211_CMD_NEW_INTERFACE &&
+                cmd != NL80211_CMD_DEL_INTERFACE);
+
+        msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+        if (!msg)
+                return;
+
+        if (nl80211_send_iface(msg, 0, 0, 0, rdev, wdev,
+                               cmd == NL80211_CMD_DEL_INTERFACE) < 0) {
+                nlmsg_free(msg);
+                return;
+        }
+
+        genlmsg_multicast_netns(&nl80211_fam, wiphy_net(&rdev->wiphy), msg, 0,
+                                NL80211_MCGRP_CONFIG, GFP_KERNEL);
+}
+
 static int nl80211_add_scan_req(struct sk_buff *msg,
                                 struct cfg80211_registered_device *rdev)
 {
diff --git a/net/wireless/nl80211.h b/net/wireless/nl80211.h
index a63f402b10b7..7e3821d7fcc5 100644
--- a/net/wireless/nl80211.h
+++ b/net/wireless/nl80211.h
@@ -7,6 +7,9 @@ int nl80211_init(void);
 void nl80211_exit(void);
 void nl80211_notify_wiphy(struct cfg80211_registered_device *rdev,
                           enum nl80211_commands cmd);
+void nl80211_notify_iface(struct cfg80211_registered_device *rdev,
+                          struct wireless_dev *wdev,
+                          enum nl80211_commands cmd);
 void nl80211_send_scan_start(struct cfg80211_registered_device *rdev,
                              struct wireless_dev *wdev);
 struct sk_buff *nl80211_build_scan_msg(struct cfg80211_registered_device *rdev,