net: Use link/peer netns in newlink() of rtnl_link_ops

Add two helper functions - rtnl_newlink_link_net() and
rtnl_newlink_peer_net() for netns fallback logic. Peer netns falls back
to link netns, and link netns falls back to source netns.

Convert the use of params->net in netdevice drivers to one of the helper
functions for clarity.

Signed-off-by: Xiao Liang <[e-mail]>
Reviewed-by: Kuniyuki Iwashima <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/infiniband/ulp/ipoib/ipoib_netlink.c

···
 				struct rtnl_newlink_params *params,
 				struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct net_device *pdev;
 	struct ipoib_dev_priv *ppriv;
···
 	if (!tb[IFLA_LINK])
 		return -EINVAL;
 
-	pdev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+	pdev = __dev_get_by_index(link_net, nla_get_u32(tb[IFLA_LINK]));
 	if (!pdev || pdev->type != ARPHRD_INFINIBAND)
 		return -ENODEV;
 

drivers/net/amt.c

···
 		       struct rtnl_newlink_params *params,
 		       struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct amt_dev *amt = netdev_priv(dev);
 	struct nlattr **data = params->data;
 	struct nlattr **tb = params->tb;
-	struct net *net = params->net;
 	int err = -EINVAL;
 
-	amt->net = net;
+	amt->net = link_net;
 	amt->mode = nla_get_u32(data[IFLA_AMT_MODE]);
 
 	if (data[IFLA_AMT_MAX_TUNNELS] &&
···
 	amt->hash_buckets = AMT_HSIZE;
 	amt->nr_tunnels = 0;
 	get_random_bytes(&amt->hash_seed, sizeof(amt->hash_seed));
-	amt->stream_dev = dev_get_by_index(net,
+	amt->stream_dev = dev_get_by_index(link_net,
 					   nla_get_u32(data[IFLA_AMT_LINK]));
 	if (!amt->stream_dev) {
 		NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_AMT_LINK],

drivers/net/bareudp.c

···
 			   struct rtnl_newlink_params *params,
 			   struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **data = params->data;
 	struct nlattr **tb = params->tb;
-	struct net *net = params->net;
 	struct bareudp_conf conf;
 	int err;
 
···
 	if (err)
 		return err;
 
-	err = bareudp_configure(net, dev, &conf, extack);
+	err = bareudp_configure(link_net, dev, &conf, extack);
 	if (err)
 		return err;
 

drivers/net/can/vxcan.c

···
 			 struct rtnl_newlink_params *params,
 			 struct netlink_ext_ack *extack)
 {
+	struct net *peer_net = rtnl_newlink_peer_net(params);
 	struct nlattr **data = params->data;
-	struct net *peer_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct vxcan_priv *priv;
 	struct net_device *peer;

drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c

···
 			 struct rtnl_newlink_params *params,
 			 struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	u32 data_format = RMNET_FLAGS_INGRESS_DEAGGREGATION;
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct net_device *real_dev;
 	int mode = RMNET_EPMODE_VND;
···
 		return -EINVAL;
 	}
 
-	real_dev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+	real_dev = __dev_get_by_index(link_net, nla_get_u32(tb[IFLA_LINK]));
 	if (!real_dev) {
 		NL_SET_ERR_MSG_MOD(extack, "link does not exist");
 		return -ENODEV;

drivers/net/geneve.c

···
 			  struct rtnl_newlink_params *params,
 			  struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **data = params->data;
 	struct nlattr **tb = params->tb;
-	struct net *net = params->net;
 	struct geneve_config cfg = {
 		.df = GENEVE_DF_UNSET,
 		.use_udp6_rx_checksums = false,
···
 	if (err)
 		return err;
 
-	err = geneve_configure(net, dev, extack, &cfg);
+	err = geneve_configure(link_net, dev, extack, &cfg);
 	if (err)
 		return err;
 

drivers/net/gtp.c

···
 		       struct rtnl_newlink_params *params,
 		       struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	unsigned int role = GTP_ROLE_GGSN;
 	struct gtp_dev *gtp;
 	struct gtp_net *gn;
···
 	gtp->restart_count = nla_get_u8_default(data[IFLA_GTP_RESTART_COUNT],
 						0);
 
-	gtp->net = src_net;
+	gtp->net = link_net;
 
 	err = gtp_hashtable_new(gtp, hashsize);
 	if (err < 0)
···
 		goto out_encap;
 	}
 
-	gn = net_generic(src_net, gtp_net_id);
+	gn = net_generic(link_net, gtp_net_id);
 	list_add(&gtp->list, &gn->gtp_dev_list);
 	dev->priv_destructor = gtp_destructor;
 

drivers/net/ipvlan/ipvlan_main.c

···
 int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
 		    struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct ipvl_dev *ipvlan = netdev_priv(dev);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct ipvl_port *port;
 	struct net_device *phy_dev;
···
 	if (!tb[IFLA_LINK])
 		return -EINVAL;
 
-	phy_dev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+	phy_dev = __dev_get_by_index(link_net, nla_get_u32(tb[IFLA_LINK]));
 	if (!phy_dev)
 		return -ENODEV;
 

drivers/net/macsec.c

···
 			  struct rtnl_newlink_params *params,
 			  struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct macsec_dev *macsec = macsec_priv(dev);
 	struct nlattr **data = params->data;
 	struct nlattr **tb = params->tb;
-	struct net *net = params->net;
 	rx_handler_func_t *rx_handler;
 	u8 icv_len = MACSEC_DEFAULT_ICV_LEN;
 	struct net_device *real_dev;
···
 
 	if (!tb[IFLA_LINK])
 		return -EINVAL;
-	real_dev = __dev_get_by_index(net, nla_get_u32(tb[IFLA_LINK]));
+	real_dev = __dev_get_by_index(link_net, nla_get_u32(tb[IFLA_LINK]));
 	if (!real_dev)
 		return -ENODEV;
 	if (real_dev->type != ARPHRD_ETHER)

drivers/net/macvlan.c

···
 			   struct rtnl_newlink_params *params,
 			   struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct macvlan_dev *vlan = netdev_priv(dev);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct net_device *lowerdev;
 	struct macvlan_port *port;
···
 	if (!tb[IFLA_LINK])
 		return -EINVAL;
 
-	lowerdev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+	lowerdev = __dev_get_by_index(link_net, nla_get_u32(tb[IFLA_LINK]));
 	if (lowerdev == NULL)
 		return -ENODEV;
 

drivers/net/netkit.c

···
 			   struct rtnl_newlink_params *params,
 			   struct netlink_ext_ack *extack)
 {
+	struct net *peer_net = rtnl_newlink_peer_net(params);
 	enum netkit_scrub scrub_prim = NETKIT_SCRUB_DEFAULT;
 	enum netkit_scrub scrub_peer = NETKIT_SCRUB_DEFAULT;
 	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp, *attr;
 	enum netkit_action policy_prim = NETKIT_PASS;
 	enum netkit_action policy_peer = NETKIT_PASS;
 	struct nlattr **data = params->data;
-	struct net *peer_net = params->net;
 	enum netkit_mode mode = NETKIT_L3;
 	unsigned char ifname_assign_type;
 	struct nlattr **tb = params->tb;

drivers/net/pfcp.c

···
 			struct rtnl_newlink_params *params,
 			struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct pfcp_dev *pfcp = netdev_priv(dev);
-	struct net *net = params->net;
 	struct pfcp_net *pn;
 	int err;
 
-	pfcp->net = net;
+	pfcp->net = link_net;
 
 	err = pfcp_add_sock(pfcp);
 	if (err) {
···
 		goto exit_del_pfcp_sock;
 	}
 
-	pn = net_generic(net, pfcp_net_id);
+	pn = net_generic(link_net, pfcp_net_id);
 	list_add(&pfcp->list, &pn->pfcp_dev_list);
 
 	netdev_dbg(dev, "registered new PFCP interface\n");

drivers/net/ppp/ppp_generic.c

···
 			  struct rtnl_newlink_params *params,
 			  struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct ppp_config conf = {
 		.unit = -1,
···
 	if (!tb[IFLA_IFNAME] || !nla_len(tb[IFLA_IFNAME]) || !*(char *)nla_data(tb[IFLA_IFNAME]))
 		conf.ifname_is_set = false;
 
-	err = ppp_dev_configure(src_net, dev, &conf);
+	err = ppp_dev_configure(link_net, dev, &conf);
 
 out_unlock:
 	mutex_unlock(&ppp_mutex);

drivers/net/veth.c

···
 			struct rtnl_newlink_params *params,
 			struct netlink_ext_ack *extack)
 {
+	struct net *peer_net = rtnl_newlink_peer_net(params);
 	struct nlattr **data = params->data;
-	struct net *peer_net = params->net;
 	struct nlattr **tb = params->tb;
 	int err;
 	struct net_device *peer;

drivers/net/vxlan/vxlan_core.c

···
 			 struct rtnl_newlink_params *params,
 			 struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct vxlan_config conf;
 	int err;
···
 	if (err)
 		return err;
 
-	return __vxlan_dev_create(src_net, dev, &conf, extack);
+	return __vxlan_dev_create(link_net, dev, &conf, extack);
 }
 
 static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[],

drivers/net/wireguard/device.c

···
 		      struct rtnl_newlink_params *params,
 		      struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct wg_device *wg = netdev_priv(dev);
-	struct net *src_net = params->net;
 	int ret = -ENOMEM;
 
-	rcu_assign_pointer(wg->creating_net, src_net);
+	rcu_assign_pointer(wg->creating_net, link_net);
 	init_rwsem(&wg->static_identity.lock);
 	mutex_init(&wg->socket_update_lock);
 	mutex_init(&wg->device_update_lock);

drivers/net/wireless/virtual/virt_wifi.c

···
 			     struct netlink_ext_ack *extack)
 {
 	struct virt_wifi_netdev_priv *priv = netdev_priv(dev);
-	struct net *src_net = params->net;
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **tb = params->tb;
 	int err;
 
···
 	netif_carrier_off(dev);
 
 	priv->upperdev = dev;
-	priv->lowerdev = __dev_get_by_index(src_net,
+	priv->lowerdev = __dev_get_by_index(link_net,
 					    nla_get_u32(tb[IFLA_LINK]));
 
 	if (!priv->lowerdev)

drivers/net/wwan/wwan_core.c

···
 	struct nlattr *tb[IFLA_MAX + 1], *linkinfo[IFLA_INFO_MAX + 1];
 	struct nlattr *data[IFLA_WWAN_MAX + 1];
 	struct rtnl_newlink_params params = {
-		.net = &init_net,
+		.src_net = &init_net,
 		.tb = tb,
 		.data = data,
 	};

include/net/rtnetlink.h

···
 	struct nlattr **data;
 };
 
+/* Get effective link netns from newlink params. Generally, this is link_net
+ * and falls back to src_net. But for compatibility, a driver may * choose to
+ * use dev_net(dev) instead.
+ */
+static inline struct net *rtnl_newlink_link_net(struct rtnl_newlink_params *p)
+{
+	return p->link_net ? : p->src_net;
+}
+
+/* Get peer netns from newlink params. Fallback to link netns if peer netns is
+ * not specified explicitly.
+ */
+static inline struct net *rtnl_newlink_peer_net(struct rtnl_newlink_params *p)
+{
+	return p->peer_net ? : rtnl_newlink_link_net(p);
+}
+
 /**
  *	struct rtnl_link_ops - rtnetlink link operations
  *

net/8021q/vlan_netlink.c

···
 			struct rtnl_newlink_params *params,
 			struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	struct nlattr **tb = params->tb;
 	struct net_device *real_dev;
 	unsigned int max_mtu;
···
 		return -EINVAL;
 	}
 
-	real_dev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+	real_dev = __dev_get_by_index(link_net, nla_get_u32(tb[IFLA_LINK]));
 	if (!real_dev) {
 		NL_SET_ERR_MSG_MOD(extack, "link does not exist");
 		return -ENODEV;

net/hsr/hsr_netlink.c

···
 		       struct rtnl_newlink_params *params,
 		       struct netlink_ext_ack *extack)
 {
+	struct net *link_net = rtnl_newlink_link_net(params);
 	struct nlattr **data = params->data;
-	struct net *src_net = params->net;
 	enum hsr_version proto_version;
 	unsigned char multicast_spec;
 	u8 proto = HSR_PROTOCOL_HSR;
···
 		NL_SET_ERR_MSG_MOD(extack, "Slave1 device not specified");
 		return -EINVAL;
 	}
-	link[0] = __dev_get_by_index(src_net,
+	link[0] = __dev_get_by_index(link_net,
 				     nla_get_u32(data[IFLA_HSR_SLAVE1]));
 	if (!link[0]) {
 		NL_SET_ERR_MSG_MOD(extack, "Slave1 does not exist");
···
 		NL_SET_ERR_MSG_MOD(extack, "Slave2 device not specified");
 		return -EINVAL;
 	}
-	link[1] = __dev_get_by_index(src_net,
+	link[1] = __dev_get_by_index(link_net,
 				     nla_get_u32(data[IFLA_HSR_SLAVE2]));
 	if (!link[1]) {
 		NL_SET_ERR_MSG_MOD(extack, "Slave2 does not exist");
···
 	}
 
 	if (data[IFLA_HSR_INTERLINK])
-		interlink = __dev_get_by_index(src_net,
+		interlink = __dev_get_by_index(link_net,
 					       nla_get_u32(data[IFLA_HSR_INTERLINK]));
 
 	if (interlink && interlink == link[0]) {