nl80211: Allow GET_INTERFACE dumps to be filtered

This patch allows GET_INTERFACE dumps to be filtered based on
NL80211_ATTR_WIPHY or NL80211_ATTR_WDEV.  The documentation for
GET_INTERFACE mentions that this is possible:
"Request an interface's configuration; either a dump request on
a %NL80211_ATTR_WIPHY or ..."

However, this behavior has not been implemented until now.

Johannes: rewrite most of the patch:
 * use nl80211_dump_wiphy_parse() to also allow passing an interface
   to be able to dump its siblings
 * fix locking (must hold rtnl around using nl80211_fam.attrbuf)
 * make init self-contained instead of relying on other cb->args

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

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 4997857..7ebad35 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2525,10 +2525,35 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
        int if_idx = 0;
        int wp_start = cb->args[0];
        int if_start = cb->args[1];
+       int filter_wiphy = -1;
        struct cfg80211_registered_device *rdev;
        struct wireless_dev *wdev;
 
        rtnl_lock();
+       if (!cb->args[2]) {
+               struct nl80211_dump_wiphy_state state = {
+                       .filter_wiphy = -1,
+               };
+               int ret;
+
+               ret = nl80211_dump_wiphy_parse(skb, cb, &state);
+               if (ret)
+                       return ret;
+
+               filter_wiphy = state.filter_wiphy;
+
+               /*
+                * if filtering, set cb->args[2] to +1 since 0 is the default
+                * value needed to determine that parsing is necessary.
+                */
+               if (filter_wiphy >= 0)
+                       cb->args[2] = filter_wiphy + 1;
+               else
+                       cb->args[2] = -1;
+       } else if (cb->args[2] > 0) {
+               filter_wiphy = cb->args[2] - 1;
+       }
+
        list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
                if (!net_eq(wiphy_net(&rdev->wiphy), sock_net(skb->sk)))
                        continue;
@@ -2536,6 +2561,10 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
                        wp_idx++;
                        continue;
                }
+
+               if (filter_wiphy >= 0 && filter_wiphy != rdev->wiphy_idx)
+                       continue;
+
                if_idx = 0;
 
                list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list) {