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>

include/uapi/linux/nl80211.h

@@ -2098,6 +2098,8 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_SURVEY_RADIO_STATS,
 
+	NL80211_ATTR_NETNS_FD,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,

net/core/net_namespace.c

@@ -361,6 +361,7 @@ struct net *get_net_ns_by_fd(int fd)
 	return ERR_PTR(-EINVAL);
 }
 #endif
+EXPORT_SYMBOL_GPL(get_net_ns_by_fd);
 
 struct net *get_net_ns_by_pid(pid_t pid)
 {

net/wireless/nl80211.c

@@ -397,6 +397,7 @@ static const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 	[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 @@ static int nl80211_wiphy_netns(struct sk_buff *skb, struct genl_info *info)
 	struct cfg80211_registered_device *rdev = info->user_ptr[0];
 	struct net *net;
 	int err;
-	u32 pid;
 
-	if (!info->attrs[NL80211_ATTR_PID])
-		return -EINVAL;
+	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]);
 
-	pid = nla_get_u32(info->attrs[NL80211_ATTR_PID]);
+		net = get_net_ns_by_fd(fd);
+	} else {
+		return -EINVAL;
+	}
 
-	net = get_net_ns_by_pid(pid);
 	if (IS_ERR(net))
 		return PTR_ERR(net);