nl80211: Allow set network namespace by fd

Added new NL80211_ATTR_NETNS_FD which allows to
set namespace via nl80211 by fd.

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index c5661c5..c64100e 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -397,6 +397,7 @@
 	[NL80211_ATTR_SMPS_MODE] = { .type = NLA_U8 },
 	[NL80211_ATTR_MAC_MASK] = { .len = ETH_ALEN },
 	[NL80211_ATTR_WIPHY_SELF_MANAGED_REG] = { .type = NLA_FLAG },
+	[NL80211_ATTR_NETNS_FD] = { .type = NLA_U32 },
 };
 
 /* policy for the key attributes */
@@ -7762,14 +7763,19 @@
 	struct cfg80211_registered_device *rdev = info->user_ptr[0];
 	struct net *net;
 	int err;
-	u32 pid;
 
-	if (!info->attrs[NL80211_ATTR_PID])
+	if (info->attrs[NL80211_ATTR_PID]) {
+		u32 pid = nla_get_u32(info->attrs[NL80211_ATTR_PID]);
+
+		net = get_net_ns_by_pid(pid);
+	} else if (info->attrs[NL80211_ATTR_NETNS_FD]) {
+		u32 fd = nla_get_u32(info->attrs[NL80211_ATTR_NETNS_FD]);
+
+		net = get_net_ns_by_fd(fd);
+	} else {
 		return -EINVAL;
+	}
 
-	pid = nla_get_u32(info->attrs[NL80211_ATTR_PID]);
-
-	net = get_net_ns_by_pid(pid);
 	if (IS_ERR(net))
 		return PTR_ERR(net);