ipvlan: decouple l3s mode dependencies from other modes

Right now ipvlan has a hard dependency on CONFIG_NETFILTER and
otherwise it cannot be built. However, the only ipvlan operation
mode that actually depends on netfilter is l3s, everything else
is independent of it. Break this hard dependency such that users
are able to use ipvlan l3 mode on systems where netfilter is not
compiled in.

Therefore, this adds a hidden CONFIG_IPVLAN_L3S bool which is
defaulting to y when CONFIG_NETFILTER is set in order to retain
existing behavior for l3s. All l3s related code is refactored
into ipvlan_l3s.c that is compiled in when enabled.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: Martynas Pumputis <m@lambda.lt>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 103 deletions

diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 19bdde60680c..8ec73d973079 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -9,73 +9,10 @@
 
 #include "ipvlan.h"
 
-static unsigned int ipvlan_netid __read_mostly;
-
-struct ipvlan_netns {
-	unsigned int ipvl_nf_hook_refcnt;
-};
-
-static const struct nf_hook_ops ipvl_nfops[] = {
-	{
-		.hook     = ipvlan_nf_input,
-		.pf       = NFPROTO_IPV4,
-		.hooknum  = NF_INET_LOCAL_IN,
-		.priority = INT_MAX,
-	},
-#if IS_ENABLED(CONFIG_IPV6)
-	{
-		.hook     = ipvlan_nf_input,
-		.pf       = NFPROTO_IPV6,
-		.hooknum  = NF_INET_LOCAL_IN,
-		.priority = INT_MAX,
-	},
-#endif
-};
-
-static const struct l3mdev_ops ipvl_l3mdev_ops = {
-	.l3mdev_l3_rcv = ipvlan_l3_rcv,
-};
-
-static void ipvlan_adjust_mtu(struct ipvl_dev *ipvlan, struct net_device *dev)
-{
-	ipvlan->dev->mtu = dev->mtu;
-}
-
-static int ipvlan_register_nf_hook(struct net *net)
-{
-	struct ipvlan_netns *vnet = net_generic(net, ipvlan_netid);
-	int err = 0;
-
-	if (!vnet->ipvl_nf_hook_refcnt) {
-		err = nf_register_net_hooks(net, ipvl_nfops,
-					    ARRAY_SIZE(ipvl_nfops));
-		if (!err)
-			vnet->ipvl_nf_hook_refcnt = 1;
-	} else {
-		vnet->ipvl_nf_hook_refcnt++;
-	}
-
-	return err;
-}
-
-static void ipvlan_unregister_nf_hook(struct net *net)
-{
-	struct ipvlan_netns *vnet = net_generic(net, ipvlan_netid);
-
-	if (WARN_ON(!vnet->ipvl_nf_hook_refcnt))
-		return;
-
-	vnet->ipvl_nf_hook_refcnt--;
-	if (!vnet->ipvl_nf_hook_refcnt)
-		nf_unregister_net_hooks(net, ipvl_nfops,
-					ARRAY_SIZE(ipvl_nfops));
-}
-
 static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 				struct netlink_ext_ack *extack)
 {
 	struct ipvl_dev *ipvlan;
-	struct net_device *mdev = port->dev;
 	unsigned int flags;
 	int err;
 
@@ -97,17 +34,12 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 		}
 		if (nval == IPVLAN_MODE_L3S) {
 			/* New mode is L3S */
-			err = ipvlan_register_nf_hook(read_pnet(&port->pnet));
-			if (!err) {
-				mdev->l3mdev_ops = &ipvl_l3mdev_ops;
-				mdev->priv_flags |= IFF_L3MDEV_MASTER;
-			} else
+			err = ipvlan_l3s_register(port);
+			if (err)
 				goto fail;
 		} else if (port->mode == IPVLAN_MODE_L3S) {
 			/* Old mode was L3S */
-			mdev->priv_flags &= ~IFF_L3MDEV_MASTER;
-			ipvlan_unregister_nf_hook(read_pnet(&port->pnet));
-			mdev->l3mdev_ops = NULL;
+			ipvlan_l3s_unregister(port);
 		}
 		port->mode = nval;
 	}
@@ -166,11 +98,8 @@ static void ipvlan_port_destroy(struct net_device *dev)
 	struct ipvl_port *port = ipvlan_port_get_rtnl(dev);
 	struct sk_buff *skb;
 
-	if (port->mode == IPVLAN_MODE_L3S) {
-		dev->priv_flags &= ~IFF_L3MDEV_MASTER;
-		ipvlan_unregister_nf_hook(dev_net(dev));
-		dev->l3mdev_ops = NULL;
-	}
+	if (port->mode == IPVLAN_MODE_L3S)
+		ipvlan_l3s_unregister(port);
 	netdev_rx_handler_unregister(dev);
 	cancel_work_sync(&port->wq);
 	while ((skb = __skb_dequeue(&port->backlog)) != NULL) {
@@ -446,6 +375,11 @@ static const struct header_ops ipvlan_header_ops = {
 	.cache_update	= eth_header_cache_update,
 };
 
+static void ipvlan_adjust_mtu(struct ipvl_dev *ipvlan, struct net_device *dev)
+{
+	ipvlan->dev->mtu = dev->mtu;
+}
+
 static bool netif_is_ipvlan(const struct net_device *dev)
 {
 	/* both ipvlan and ipvtap devices use the same netdev_ops */
@@ -781,7 +715,6 @@ static int ipvlan_device_event(struct notifier_block *unused,
 
 	case NETDEV_REGISTER: {
 		struct net *oldnet, *newnet = dev_net(dev);
-		struct ipvlan_netns *old_vnet;
 
 		oldnet = read_pnet(&port->pnet);
 		if (net_eq(newnet, oldnet))
@@ -789,12 +722,7 @@ static int ipvlan_device_event(struct notifier_block *unused,
 
 		write_pnet(&port->pnet, newnet);
 
-		old_vnet = net_generic(oldnet, ipvlan_netid);
-		if (!old_vnet->ipvl_nf_hook_refcnt)
-			break;
-
-		ipvlan_register_nf_hook(newnet);
-		ipvlan_unregister_nf_hook(oldnet);
+		ipvlan_migrate_l3s_hook(oldnet, newnet);
 		break;
 	}
 	case NETDEV_UNREGISTER:
@@ -1068,23 +996,6 @@ static struct notifier_block ipvlan_addr6_vtor_notifier_block __read_mostly = {
 };
 #endif
 
-static void ipvlan_ns_exit(struct net *net)
-{
-	struct ipvlan_netns *vnet = net_generic(net, ipvlan_netid);
-
-	if (WARN_ON_ONCE(vnet->ipvl_nf_hook_refcnt)) {
-		vnet->ipvl_nf_hook_refcnt = 0;
-		nf_unregister_net_hooks(net, ipvl_nfops,
-					ARRAY_SIZE(ipvl_nfops));
-	}
-}
-
-static struct pernet_operations ipvlan_net_ops = {
-	.id = &ipvlan_netid,
-	.size = sizeof(struct ipvlan_netns),
-	.exit = ipvlan_ns_exit,
-};
-
 static int __init ipvlan_init_module(void)
 {
 	int err;
@@ -1099,13 +1010,13 @@ static int __init ipvlan_init_module(void)
 	register_inetaddr_notifier(&ipvlan_addr4_notifier_block);
 	register_inetaddr_validator_notifier(&ipvlan_addr4_vtor_notifier_block);
 
-	err = register_pernet_subsys(&ipvlan_net_ops);
+	err = ipvlan_l3s_init();
 	if (err < 0)
 		goto error;
 
 	err = ipvlan_link_register(&ipvlan_link_ops);
 	if (err < 0) {
-		unregister_pernet_subsys(&ipvlan_net_ops);
+		ipvlan_l3s_cleanup();
 		goto error;
 	}
 
@@ -1126,7 +1037,7 @@ error:
 static void __exit ipvlan_cleanup_module(void)
 {
 	rtnl_link_unregister(&ipvlan_link_ops);
-	unregister_pernet_subsys(&ipvlan_net_ops);
+	ipvlan_l3s_cleanup();
 	unregister_netdevice_notifier(&ipvlan_notifier_block);
 	unregister_inetaddr_notifier(&ipvlan_addr4_notifier_block);
 	unregister_inetaddr_validator_notifier(