ipvlan: Introduce l3s mode

In a typical IPvlan L3 setup where master is in default-ns and
each slave is into different (slave) ns. In this setup egress
packet processing for traffic originating from slave-ns will
hit all NF_HOOKs in slave-ns as well as default-ns. However same
is not true for ingress processing. All these NF_HOOKs are
hit only in the slave-ns skipping them in the default-ns.
IPvlan in L3 mode is restrictive and if admins want to deploy
iptables rules in default-ns, this asymmetric data path makes it
impossible to do so.

This patch makes use of the l3_rcv() (added as part of l3mdev
enhancements) to perform input route lookup on RX packets without
changing the skb->dev and then uses nf_hook at NF_INET_LOCAL_IN
to change the skb->dev just before handing over skb to L4.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
CC: David Ahern <dsa@cumulusnetworks.com>
Reviewed-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 180 insertions, 7 deletions

diff --git a/drivers/net/ipvlan/ipvlan.h b/drivers/net/ipvlan/ipvlan.h
index 695a5dc9ace3..7e0732f5ea07 100644
--- a/drivers/net/ipvlan/ipvlan.h
+++ b/drivers/net/ipvlan/ipvlan.h
@@ -23,11 +23,13 @@
 #include <linux/if_vlan.h>
 #include <linux/ip.h>
 #include <linux/inetdevice.h>
+#include <linux/netfilter.h>
 #include <net/ip.h>
 #include <net/ip6_route.h>
 #include <net/rtnetlink.h>
 #include <net/route.h>
 #include <net/addrconf.h>
+#include <net/l3mdev.h>
 
 #define IPVLAN_DRV	"ipvlan"
 #define IPV_DRV_VER	"0.1"
@@ -124,4 +126,8 @@ struct ipvl_addr *ipvlan_find_addr(const struct ipvl_dev *ipvlan,
 				   const void *iaddr, bool is_v6);
 bool ipvlan_addr_busy(struct ipvl_port *port, void *iaddr, bool is_v6);
 void ipvlan_ht_addr_del(struct ipvl_addr *addr);
+struct sk_buff *ipvlan_l3_rcv(struct net_device *dev, struct sk_buff *skb,
+			      u16 proto);
+unsigned int ipvlan_nf_input(void *priv, struct sk_buff *skb,
+			     const struct nf_hook_state *state);
 #endif /* __IPVLAN_H */
diff --git a/drivers/net/ipvlan/ipvlan_core.c b/drivers/net/ipvlan/ipvlan_core.c
index b5f9511d819e..b4e990743e1d 100644
--- a/drivers/net/ipvlan/ipvlan_core.c
+++ b/drivers/net/ipvlan/ipvlan_core.c
@@ -560,6 +560,7 @@ int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 	case IPVLAN_MODE_L2:
 		return ipvlan_xmit_mode_l2(skb, dev);
 	case IPVLAN_MODE_L3:
+	case IPVLAN_MODE_L3S:
 		return ipvlan_xmit_mode_l3(skb, dev);
 	}
 
@@ -664,6 +665,8 @@ rx_handler_result_t ipvlan_handle_frame(struct sk_buff **pskb)
 		return ipvlan_handle_mode_l2(pskb, port);
 	case IPVLAN_MODE_L3:
 		return ipvlan_handle_mode_l3(pskb, port);
+	case IPVLAN_MODE_L3S:
+		return RX_HANDLER_PASS;
 	}
 
 	/* Should not reach here */
@@ -672,3 +675,94 @@ rx_handler_result_t ipvlan_handle_frame(struct sk_buff **pskb)
 	kfree_skb(skb);
 	return RX_HANDLER_CONSUMED;
 }
+
+static struct ipvl_addr *ipvlan_skb_to_addr(struct sk_buff *skb,
+					    struct net_device *dev)
+{
+	struct ipvl_addr *addr = NULL;
+	struct ipvl_port *port;
+	void *lyr3h;
+	int addr_type;
+
+	if (!dev || !netif_is_ipvlan_port(dev))
+		goto out;
+
+	port = ipvlan_port_get_rcu(dev);
+	if (!port || port->mode != IPVLAN_MODE_L3S)
+		goto out;
+
+	lyr3h = ipvlan_get_L3_hdr(skb, &addr_type);
+	if (!lyr3h)
+		goto out;
+
+	addr = ipvlan_addr_lookup(port, lyr3h, addr_type, true);
+out:
+	return addr;
+}
+
+struct sk_buff *ipvlan_l3_rcv(struct net_device *dev, struct sk_buff *skb,
+			      u16 proto)
+{
+	struct ipvl_addr *addr;
+	struct net_device *sdev;
+
+	addr = ipvlan_skb_to_addr(skb, dev);
+	if (!addr)
+		goto out;
+
+	sdev = addr->master->dev;
+	switch (proto) {
+	case AF_INET:
+	{
+		int err;
+		struct iphdr *ip4h = ip_hdr(skb);
+
+		err = ip_route_input_noref(skb, ip4h->daddr, ip4h->saddr,
+					   ip4h->tos, sdev);
+		if (unlikely(err))
+			goto out;
+		break;
+	}
+	case AF_INET6:
+	{
+		struct dst_entry *dst;
+		struct ipv6hdr *ip6h = ipv6_hdr(skb);
+		int flags = RT6_LOOKUP_F_HAS_SADDR;
+		struct flowi6 fl6 = {
+			.flowi6_iif   = sdev->ifindex,
+			.daddr        = ip6h->daddr,
+			.saddr        = ip6h->saddr,
+			.flowlabel    = ip6_flowinfo(ip6h),
+			.flowi6_mark  = skb->mark,
+			.flowi6_proto = ip6h->nexthdr,
+		};
+
+		skb_dst_drop(skb);
+		dst = ip6_route_input_lookup(dev_net(sdev), sdev, &fl6, flags);
+		skb_dst_set(skb, dst);
+		break;
+	}
+	default:
+		break;
+	}
+
+out:
+	return skb;
+}
+
+unsigned int ipvlan_nf_input(void *priv, struct sk_buff *skb,
+			     const struct nf_hook_state *state)
+{
+	struct ipvl_addr *addr;
+	unsigned int len;
+
+	addr = ipvlan_skb_to_addr(skb, skb->dev);
+	if (!addr)
+		goto out;
+
+	skb->dev = addr->master->dev;
+	len = skb->len + ETH_HLEN;
+	ipvlan_count_rx(addr->master, len, true, false);
+out:
+	return NF_ACCEPT;
+}
diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 18b4e8c7f68a..f442eb366863 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -9,24 +9,87 @@
 
 #include "ipvlan.h"
 
+static u32 ipvl_nf_hook_refcnt = 0;
+
+static struct nf_hook_ops ipvl_nfops[] __read_mostly = {
+	{
+		.hook     = ipvlan_nf_input,
+		.pf       = NFPROTO_IPV4,
+		.hooknum  = NF_INET_LOCAL_IN,
+		.priority = INT_MAX,
+	},
+	{
+		.hook     = ipvlan_nf_input,
+		.pf       = NFPROTO_IPV6,
+		.hooknum  = NF_INET_LOCAL_IN,
+		.priority = INT_MAX,
+	},
+};
+
+static struct l3mdev_ops ipvl_l3mdev_ops __read_mostly = {
+	.l3mdev_l3_rcv = ipvlan_l3_rcv,
+};
+
 static void ipvlan_adjust_mtu(struct ipvl_dev *ipvlan, struct net_device *dev)
 {
 	ipvlan->dev->mtu = dev->mtu - ipvlan->mtu_adj;
 }
 
-static void ipvlan_set_port_mode(struct ipvl_port *port, u16 nval)
+static int ipvlan_register_nf_hook(void)
+{
+	int err = 0;
+
+	if (!ipvl_nf_hook_refcnt) {
+		err = _nf_register_hooks(ipvl_nfops, ARRAY_SIZE(ipvl_nfops));
+		if (!err)
+			ipvl_nf_hook_refcnt = 1;
+	} else {
+		ipvl_nf_hook_refcnt++;
+	}
+
+	return err;
+}
+
+static void ipvlan_unregister_nf_hook(void)
+{
+	WARN_ON(!ipvl_nf_hook_refcnt);
+
+	ipvl_nf_hook_refcnt--;
+	if (!ipvl_nf_hook_refcnt)
+		_nf_unregister_hooks(ipvl_nfops, ARRAY_SIZE(ipvl_nfops));
+}
+
+static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval)
 {
 	struct ipvl_dev *ipvlan;
+	struct net_device *mdev = port->dev;
+	int err = 0;
 
+	ASSERT_RTNL();
 	if (port->mode != nval) {
+		if (nval == IPVLAN_MODE_L3S) {
+			/* New mode is L3S */
+			err = ipvlan_register_nf_hook();
+			if (!err) {
+				mdev->l3mdev_ops = &ipvl_l3mdev_ops;
+				mdev->priv_flags |= IFF_L3MDEV_MASTER;
+			} else
+				return err;
+		} else if (port->mode == IPVLAN_MODE_L3S) {
+			/* Old mode was L3S */
+			mdev->priv_flags &= ~IFF_L3MDEV_MASTER;
+			ipvlan_unregister_nf_hook();
+			mdev->l3mdev_ops = NULL;
+		}
 		list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
-			if (nval == IPVLAN_MODE_L3)
+			if (nval == IPVLAN_MODE_L3 || nval == IPVLAN_MODE_L3S)
 				ipvlan->dev->flags |= IFF_NOARP;
 			else
 				ipvlan->dev->flags &= ~IFF_NOARP;
 		}
 		port->mode = nval;
 	}
+	return err;
 }
 
 static int ipvlan_port_create(struct net_device *dev)
@@ -74,6 +137,11 @@ static void ipvlan_port_destroy(struct net_device *dev)
 	struct ipvl_port *port = ipvlan_port_get_rtnl(dev);
 
 	dev->priv_flags &= ~IFF_IPVLAN_MASTER;
+	if (port->mode == IPVLAN_MODE_L3S) {
+		dev->priv_flags &= ~IFF_L3MDEV_MASTER;
+		ipvlan_unregister_nf_hook();
+		dev->l3mdev_ops = NULL;
+	}
 	netdev_rx_handler_unregister(dev);
 	cancel_work_sync(&port->wq);
 	__skb_queue_purge(&port->backlog);
@@ -132,7 +200,8 @@ static int ipvlan_open(struct net_device *dev)
 	struct net_device *phy_dev = ipvlan->phy_dev;
 	struct ipvl_addr *addr;
 
-	if (ipvlan->port->mode == IPVLAN_MODE_L3)
+	if (ipvlan->port->mode == IPVLAN_MODE_L3 ||
+	    ipvlan->port->mode == IPVLAN_MODE_L3S)
 		dev->flags |= IFF_NOARP;
 	else
 		dev->flags &= ~IFF_NOARP;
@@ -372,13 +441,14 @@ static int ipvlan_nl_changelink(struct net_device *dev,
 {
 	struct ipvl_dev *ipvlan = netdev_priv(dev);
 	struct ipvl_port *port = ipvlan_port_get_rtnl(ipvlan->phy_dev);
+	int err = 0;
 
 	if (data && data[IFLA_IPVLAN_MODE]) {
 		u16 nmode = nla_get_u16(data[IFLA_IPVLAN_MODE]);
 
-		ipvlan_set_port_mode(port, nmode);
+		err = ipvlan_set_port_mode(port, nmode);
 	}
-	return 0;
+	return err;
 }
 
 static size_t ipvlan_nl_getsize(const struct net_device *dev)
@@ -473,10 +543,13 @@ static int ipvlan_link_new(struct net *src_net, struct net_device *dev,
 		unregister_netdevice(dev);
 		return err;
 	}
+	err = ipvlan_set_port_mode(port, mode);
+	if (err) {
+		unregister_netdevice(dev);
+		return err;
+	}
 
 	list_add_tail_rcu(&ipvlan->pnode, &port->ipvlans);
-	ipvlan_set_port_mode(port, mode);
-
 	netif_stacked_transfer_operstate(phy_dev, dev);
 	return 0;
 }