[PATCH net-next 01/14] ipvlan: Preparation to support mac-nat

[PATCH net-next 01/14] ipvlan: Preparation to support mac-nat

[Dmitry Skorodumov]

Now it is possible to create link in L2_MACNAT mode. In this patch
it is just a learnable bridge: the IPs of slaves are learned
from TX-packets of child interfaces. But in later patches
it will be extended also to collect MAC-addresses for translation.

Also, dev_add_pack() protocol is attached to the main port
to support communication from main to child interfaces.

This mode is intended for the desktop virtual machines, for
bridging to Wireless interfaces.

The mode should be specified while creating first child interface.
It is not possible to change it after this.

The maximum number of addresses on child interface is limited.
There can be IPVLAN_MAX_MACNAT_ADDRS of each (ipv4/ipv6) types.

Signed-off-by: Dmitry Skorodumov <skorodumov.dmitry@huawei.com>
---
 Documentation/networking/ipvlan.rst |  11 ++
 drivers/net/ipvlan/ipvlan.h         |  25 ++++
 drivers/net/ipvlan/ipvlan_core.c    | 196 +++++++++++++++++++++++++---
 drivers/net/ipvlan/ipvlan_main.c    | 138 +++++++++++++++++---
 include/uapi/linux/if_link.h        |   1 +
 5 files changed, 337 insertions(+), 34 deletions(-)

diff --git a/Documentation/networking/ipvlan.rst b/Documentation/networking/ipvlan.rst
index 895d0ccfd596..e1a15ae87bdf 100644
--- a/Documentation/networking/ipvlan.rst
+++ b/Documentation/networking/ipvlan.rst
@@ -90,6 +90,17 @@ works in this mode and hence it is L3-symmetric (L3s). This will have slightly l
 performance but that shouldn't matter since you are choosing this mode over plain-L3
 mode to make conn-tracking work.
 
+4.4 L2_MACNAT mode:
+-------------
+
+This mode is an extension for the L2 mode. It is primarily intended for
+desktop virtual machines for bridging to Wireless interfaces. In plain L2
+mode you have to configure IPs on slave interface to make it possible
+mux-ing frames between slaves/master. In the L2_MACNAT mode, ipvlan will
+learn itself IPv4/IPv6 address from outgoing packets. Moreover,
+the dev_add_pack() is configured on master interface to capture
+outgoing frames and mux-ing it to slave interfaces, if needed.
+
 5. Mode flags:
 ==============
 
diff --git a/drivers/net/ipvlan/ipvlan.h b/drivers/net/ipvlan/ipvlan.h
index 50de3ee204db..9db92ee11999 100644
--- a/drivers/net/ipvlan/ipvlan.h
+++ b/drivers/net/ipvlan/ipvlan.h
@@ -39,6 +39,8 @@
 
 #define IPVLAN_QBACKLOG_LIMIT	1000
 
+#define IPVLAN_MAX_MACNAT_ADDRS	4
+
 typedef enum {
 	IPVL_IPV6 = 0,
 	IPVL_ICMPV6,
@@ -83,6 +85,7 @@ struct ipvl_addr {
 	struct hlist_node	hlnode;  /* Hash-table linkage */
 	struct list_head	anode;   /* logical-interface linkage */
 	ipvl_hdr_type		atype;
+	u64			tstamp;
 	struct rcu_head		rcu;
 };
 
@@ -91,6 +94,7 @@ struct ipvl_port {
 	possible_net_t		pnet;
 	struct hlist_head	hlhead[IPVLAN_HASH_SIZE];
 	struct list_head	ipvlans;
+	struct packet_type	ipvl_ptype;
 	u16			mode;
 	u16			flags;
 	u16			dev_id_start;
@@ -103,6 +107,7 @@ struct ipvl_port {
 
 struct ipvl_skb_cb {
 	bool tx_pkt;
+	void *mark;
 };
 #define IPVL_SKB_CB(_skb) ((struct ipvl_skb_cb *)&((_skb)->cb[0]))
 
@@ -151,12 +156,32 @@ static inline void ipvlan_clear_vepa(struct ipvl_port *port)
 	port->flags &= ~IPVLAN_F_VEPA;
 }
 
+static inline bool ipvlan_is_macnat(struct ipvl_port *port)
+{
+	return port->mode == IPVLAN_MODE_L2_MACNAT;
+}
+
+static inline void ipvlan_mark_skb(struct sk_buff *skb, struct net_device *dev)
+{
+	IPVL_SKB_CB(skb)->mark = dev;
+}
+
+static inline bool ipvlan_is_skb_marked(struct sk_buff *skb,
+					struct net_device *dev)
+{
+	return (IPVL_SKB_CB(skb)->mark == dev);
+}
+
 void ipvlan_init_secret(void);
 unsigned int ipvlan_mac_hash(const unsigned char *addr);
 rx_handler_result_t ipvlan_handle_frame(struct sk_buff **pskb);
+void ipvlan_skb_crossing_ns(struct sk_buff *skb, struct net_device *dev);
 void ipvlan_process_multicast(struct work_struct *work);
+void ipvlan_multicast_enqueue(struct ipvl_port *port,
+			      struct sk_buff *skb, bool tx_pkt);
 int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev);
 void ipvlan_ht_addr_add(struct ipvl_dev *ipvlan, struct ipvl_addr *addr);
+int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6);
 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);
diff --git a/drivers/net/ipvlan/ipvlan_core.c b/drivers/net/ipvlan/ipvlan_core.c
index d7e3ddbcab6f..06c1c4fdc4f6 100644
--- a/drivers/net/ipvlan/ipvlan_core.c
+++ b/drivers/net/ipvlan/ipvlan_core.c
@@ -284,6 +284,18 @@ void ipvlan_process_multicast(struct work_struct *work)
 		rcu_read_unlock();
 
 		if (tx_pkt) {
+			if (ipvlan_is_macnat(port)) {
+				/* Inject packet to main dev */
+				nskb = skb_clone(skb, GFP_ATOMIC);
+				if (nskb) {
+					local_bh_disable();
+					nskb->pkt_type = pkt_type;
+					nskb->dev = port->dev;
+					dev_forward_skb(port->dev, nskb);
+					local_bh_enable();
+				}
+			}
+
 			/* If the packet originated here, send it out. */
 			skb->dev = port->dev;
 			skb->pkt_type = pkt_type;
@@ -299,7 +311,7 @@ void ipvlan_process_multicast(struct work_struct *work)
 	}
 }
 
-static void ipvlan_skb_crossing_ns(struct sk_buff *skb, struct net_device *dev)
+void ipvlan_skb_crossing_ns(struct sk_buff *skb, struct net_device *dev)
 {
 	bool xnet = true;
 
@@ -414,6 +426,107 @@ struct ipvl_addr *ipvlan_addr_lookup(struct ipvl_port *port, void *lyr3h,
 	return addr;
 }
 
+static bool is_ipv4_usable(__be32 addr)
+{
+	return !ipv4_is_lbcast(addr) && !ipv4_is_multicast(addr) &&
+	       !ipv4_is_zeronet(addr);
+}
+
+static bool is_ipv6_usable(const struct in6_addr *addr)
+{
+	return !ipv6_addr_is_multicast(addr) && !ipv6_addr_loopback(addr) &&
+	       !ipv6_addr_any(addr);
+}
+
+static void __ipvlan_addr_learn(struct ipvl_dev *ipvlan, void *addr, bool is_v6)
+{
+	const ipvl_hdr_type atype = is_v6 ? IPVL_IPV6 : IPVL_IPV4;
+	struct ipvl_addr *ipvladdr, *oldest = NULL;
+	unsigned int naddrs = 0;
+
+	spin_lock_bh(&ipvlan->addrs_lock);
+
+	if (ipvlan_addr_busy(ipvlan->port, addr, is_v6))
+		goto out_unlock;
+
+	list_for_each_entry_rcu(ipvladdr, &ipvlan->addrs, anode) {
+		if (ipvladdr->atype != atype)
+			continue;
+		naddrs++;
+		if (!oldest || time_before64(ipvladdr->tstamp, oldest->tstamp))
+			oldest = ipvladdr;
+	}
+
+	if (naddrs < IPVLAN_MAX_MACNAT_ADDRS) {
+		oldest = NULL;
+	} else {
+		ipvlan_ht_addr_del(oldest);
+		list_del_rcu(&oldest->anode);
+	}
+
+	ipvlan_add_addr(ipvlan, addr, is_v6);
+
+out_unlock:
+	spin_unlock_bh(&ipvlan->addrs_lock);
+	if (oldest)
+		kfree_rcu(oldest, rcu);
+}
+
+static void ipvlan_addr_learn(struct ipvl_dev *ipvlan, void *lyr3h,
+			      int addr_type)
+{
+	void *addr = NULL;
+	bool is_v6;
+
+	switch (addr_type) {
+#if IS_ENABLED(CONFIG_IPV6)
+	/* No need to handle IPVL_ICMPV6, it never has valid src-address. */
+	case IPVL_IPV6: {
+		struct ipv6hdr *ip6h;
+
+		ip6h = (struct ipv6hdr *)lyr3h;
+		if (!is_ipv6_usable(&ip6h->saddr))
+			return;
+		is_v6 = true;
+		addr = &ip6h->saddr;
+		break;
+	}
+#endif
+	case IPVL_IPV4: {
+		struct iphdr *ip4h;
+		__be32 *i4addr;
+
+		ip4h = (struct iphdr *)lyr3h;
+		i4addr = &ip4h->saddr;
+		if (!is_ipv4_usable(*i4addr))
+			return;
+		is_v6 = false;
+		addr = i4addr;
+		break;
+	}
+	case IPVL_ARP: {
+		struct arphdr *arph;
+		unsigned char *arp_ptr;
+		__be32 *i4addr;
+
+		arph = (struct arphdr *)lyr3h;
+		arp_ptr = (unsigned char *)(arph + 1);
+		arp_ptr += ipvlan->port->dev->addr_len;
+		i4addr = (__be32 *)arp_ptr;
+		if (!is_ipv4_usable(*i4addr))
+			return;
+		is_v6 = false;
+		addr = i4addr;
+		break;
+	}
+	default:
+		return;
+	}
+
+	if (!ipvlan_ht_addr_lookup(ipvlan->port, addr, is_v6))
+		__ipvlan_addr_learn(ipvlan, addr, is_v6);
+}
+
 static noinline_for_stack int ipvlan_process_v4_outbound(struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
@@ -561,8 +674,8 @@ static int ipvlan_process_outbound(struct sk_buff *skb)
 	return ret;
 }
 
-static void ipvlan_multicast_enqueue(struct ipvl_port *port,
-				     struct sk_buff *skb, bool tx_pkt)
+void ipvlan_multicast_enqueue(struct ipvl_port *port,
+			      struct sk_buff *skb, bool tx_pkt)
 {
 	if (skb->protocol == htons(ETH_P_PAUSE)) {
 		kfree_skb(skb);
@@ -618,15 +731,61 @@ static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
 
 static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
 {
-	const struct ipvl_dev *ipvlan = netdev_priv(dev);
-	struct ethhdr *eth = skb_eth_hdr(skb);
+	struct ipvl_dev *ipvlan;
 	struct ipvl_addr *addr;
-	void *lyr3h;
+	struct ethhdr *eth;
+	bool same_mac_addr;
 	int addr_type;
+	void *lyr3h;
+
+	ipvlan = netdev_priv(dev);
+	eth = skb_eth_hdr(skb);
+	if (ipvlan_is_macnat(ipvlan->port) &&
+	    ether_addr_equal(eth->h_source, dev->dev_addr)) {
+		/* ignore tx-packets from host */
+		goto out_drop;
+	}
+
+	same_mac_addr = ether_addr_equal(eth->h_dest, eth->h_source);
 
-	if (!ipvlan_is_vepa(ipvlan->port) &&
-	    ether_addr_equal(eth->h_dest, eth->h_source)) {
+	lyr3h = NULL;
+	if (!ipvlan_is_vepa(ipvlan->port)) {
 		lyr3h = ipvlan_get_L3_hdr(ipvlan->port, skb, &addr_type);
+
+		if (ipvlan_is_macnat(ipvlan->port)) {
+			if (lyr3h)
+				ipvlan_addr_learn(ipvlan, lyr3h, addr_type);
+			/* Mark SKB in advance */
+			skb = skb_share_check(skb, GFP_ATOMIC);
+			if (!skb)
+				return NET_XMIT_DROP;
+			ipvlan_mark_skb(skb, ipvlan->phy_dev);
+		}
+	}
+
+	if (is_multicast_ether_addr(eth->h_dest)) {
+		skb_reset_mac_header(skb);
+		ipvlan_skb_crossing_ns(skb, NULL);
+		ipvlan_multicast_enqueue(ipvlan->port, skb, true);
+		return NET_XMIT_SUCCESS;
+	}
+
+	if (ipvlan_is_vepa(ipvlan->port))
+		goto tx_phy_dev;
+
+	if (!same_mac_addr &&
+	    ether_addr_equal(eth->h_dest, ipvlan->phy_dev->dev_addr)) {
+		/* It is a packet from child with destination to main port.
+		 * Pass it to main.
+		 */
+		skb = skb_share_check(skb, GFP_ATOMIC);
+		if (!skb)
+			return NET_XMIT_DROP;
+		skb->pkt_type = PACKET_HOST;
+		skb->dev = ipvlan->phy_dev;
+		dev_forward_skb(ipvlan->phy_dev, skb);
+		return NET_XMIT_SUCCESS;
+	} else if (same_mac_addr) {
 		if (lyr3h) {
 			addr = ipvlan_addr_lookup(ipvlan->port, lyr3h, addr_type, true);
 			if (addr) {
@@ -649,16 +808,14 @@ static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
 		 */
 		dev_forward_skb(ipvlan->phy_dev, skb);
 		return NET_XMIT_SUCCESS;
-
-	} else if (is_multicast_ether_addr(eth->h_dest)) {
-		skb_reset_mac_header(skb);
-		ipvlan_skb_crossing_ns(skb, NULL);
-		ipvlan_multicast_enqueue(ipvlan->port, skb, true);
-		return NET_XMIT_SUCCESS;
 	}
 
+tx_phy_dev:
 	skb->dev = ipvlan->phy_dev;
 	return dev_queue_xmit(skb);
+out_drop:
+	consume_skb(skb);
+	return NET_XMIT_DROP;
 }
 
 int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -674,6 +831,7 @@ int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	switch(port->mode) {
 	case IPVLAN_MODE_L2:
+	case IPVLAN_MODE_L2_MACNAT:
 		return ipvlan_xmit_mode_l2(skb, dev);
 	case IPVLAN_MODE_L3:
 #ifdef CONFIG_IPVLAN_L3S
@@ -737,17 +895,22 @@ static rx_handler_result_t ipvlan_handle_mode_l2(struct sk_buff **pskb,
 	struct ethhdr *eth = eth_hdr(skb);
 	rx_handler_result_t ret = RX_HANDLER_PASS;
 
+	/* Ignore already seen packets. */
+	if (ipvlan_is_skb_marked(skb, port->dev))
+		return RX_HANDLER_PASS;
+
 	if (is_multicast_ether_addr(eth->h_dest)) {
 		if (ipvlan_external_frame(skb, port)) {
-			struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
-
 			/* External frames are queued for device local
 			 * distribution, but a copy is given to master
 			 * straight away to avoid sending duplicates later
 			 * when work-queue processes this frame. This is
 			 * achieved by returning RX_HANDLER_PASS.
 			 */
+			struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
 			if (nskb) {
+				ipvlan_mark_skb(skb, port->dev);
 				ipvlan_skb_crossing_ns(nskb, NULL);
 				ipvlan_multicast_enqueue(port, nskb, false);
 			}
@@ -770,6 +933,7 @@ rx_handler_result_t ipvlan_handle_frame(struct sk_buff **pskb)
 
 	switch (port->mode) {
 	case IPVLAN_MODE_L2:
+	case IPVLAN_MODE_L2_MACNAT:
 		return ipvlan_handle_mode_l2(pskb, port);
 	case IPVLAN_MODE_L3:
 		return ipvlan_handle_mode_l3(pskb, port);
diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 660f3db11766..4535a9ab50da 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -16,6 +16,15 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 
 	ASSERT_RTNL();
 	if (port->mode != nval) {
+		/* Don't allow switch off the learnable bridge mode.
+		 * Flags also must be set from the first port-link setup.
+		 */
+		if (port->mode == IPVLAN_MODE_L2_MACNAT ||
+		    (nval == IPVLAN_MODE_L2_MACNAT && port->count > 1)) {
+			netdev_err(port->dev, "MACNAT mode cannot be changed.\n");
+			return -EINVAL;
+		}
+
 		list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
 			flags = ipvlan->dev->flags;
 			if (nval == IPVLAN_MODE_L3 || nval == IPVLAN_MODE_L3S) {
@@ -40,7 +49,10 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 			ipvlan_l3s_unregister(port);
 		}
 		port->mode = nval;
+		if (port->mode == IPVLAN_MODE_L2_MACNAT)
+			dev_add_pack(&port->ipvl_ptype);
 	}
+
 	return 0;
 
 fail:
@@ -59,6 +71,66 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 	return err;
 }
 
+static int ipvlan_port_rcv(struct sk_buff *skb, struct net_device *wdev,
+			   struct packet_type *pt, struct net_device *orig_wdev)
+{
+	struct ipvl_port *port;
+	struct ipvl_addr *addr;
+	struct ethhdr *eth;
+	int addr_type;
+	void *lyr3h;
+
+	port = container_of(pt, struct ipvl_port, ipvl_ptype);
+	/* We are interested only in outgoing packets.
+	 * rx-path is handled in rx_handler().
+	 */
+	if (skb->pkt_type != PACKET_OUTGOING ||
+	    ipvlan_is_skb_marked(skb, port->dev))
+		goto out;
+
+	skb = skb_share_check(skb, GFP_ATOMIC);
+	if (!skb)
+		goto no_mem;
+
+	/* data should point to eth-header */
+	skb_push(skb, skb->data - skb_mac_header(skb));
+	skb->dev = port->dev;
+	eth = eth_hdr(skb);
+
+	if (is_multicast_ether_addr(eth->h_dest)) {
+		ipvlan_skb_crossing_ns(skb, NULL);
+		skb->protocol = eth_type_trans(skb, skb->dev);
+		skb->pkt_type = PACKET_HOST;
+		ipvlan_mark_skb(skb, port->dev);
+		ipvlan_multicast_enqueue(port, skb, false);
+		return NET_RX_SUCCESS;
+	}
+
+	lyr3h = ipvlan_get_L3_hdr(port, skb, &addr_type);
+	if (!lyr3h)
+		goto out;
+
+	addr = ipvlan_addr_lookup(port, lyr3h, addr_type, true);
+	if (addr) {
+		struct ipvl_dev *ipvlan = addr->master;
+		int ret, len;
+
+		ipvlan_skb_crossing_ns(skb, ipvlan->dev);
+		skb->protocol = eth_type_trans(skb, skb->dev);
+		skb->pkt_type = PACKET_HOST;
+		ipvlan_mark_skb(skb, port->dev);
+		len = skb->len + ETH_HLEN;
+		ret = netif_rx(skb);
+		ipvlan_count_rx(ipvlan, len, ret == NET_RX_SUCCESS, false);
+		return NET_RX_SUCCESS;
+	}
+
+out:
+	dev_kfree_skb(skb);
+no_mem:
+	return NET_RX_DROP;
+}
+
 static int ipvlan_port_create(struct net_device *dev)
 {
 	struct ipvl_port *port;
@@ -84,6 +156,11 @@ static int ipvlan_port_create(struct net_device *dev)
 	if (err)
 		goto err;
 
+	port->ipvl_ptype.func = ipvlan_port_rcv;
+	port->ipvl_ptype.type = htons(ETH_P_ALL);
+	port->ipvl_ptype.dev = dev;
+	port->ipvl_ptype.list.prev = LIST_POISON2;
+
 	netdev_hold(dev, &port->dev_tracker, GFP_KERNEL);
 	return 0;
 
@@ -100,6 +177,8 @@ static void ipvlan_port_destroy(struct net_device *dev)
 	netdev_put(dev, &port->dev_tracker);
 	if (port->mode == IPVLAN_MODE_L3S)
 		ipvlan_l3s_unregister(port);
+	if (port->ipvl_ptype.list.prev != LIST_POISON2)
+		dev_remove_pack(&port->ipvl_ptype);
 	netdev_rx_handler_unregister(dev);
 	cancel_work_sync(&port->wq);
 	while ((skb = __skb_dequeue(&port->backlog)) != NULL) {
@@ -189,10 +268,13 @@ static int ipvlan_open(struct net_device *dev)
 	else
 		dev->flags &= ~IFF_NOARP;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(addr, &ipvlan->addrs, anode)
-		ipvlan_ht_addr_add(ipvlan, addr);
-	rcu_read_unlock();
+	/* for learnable, addresses will be obtained from tx-packets. */
+	if (!ipvlan_is_macnat(ipvlan->port)) {
+		rcu_read_lock();
+		list_for_each_entry_rcu(addr, &ipvlan->addrs, anode)
+			ipvlan_ht_addr_add(ipvlan, addr);
+		rcu_read_unlock();
+	}
 
 	return 0;
 }
@@ -581,11 +663,21 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
 	INIT_LIST_HEAD(&ipvlan->addrs);
 	spin_lock_init(&ipvlan->addrs_lock);
 
-	/* TODO Probably put random address here to be presented to the
-	 * world but keep using the physical-dev address for the outgoing
-	 * packets.
+	/* Flags are per port and latest update overrides. User has
+	 * to be consistent in setting it just like the mode attribute.
 	 */
-	eth_hw_addr_set(dev, phy_dev->dev_addr);
+	if (data && data[IFLA_IPVLAN_MODE])
+		mode = nla_get_u16(data[IFLA_IPVLAN_MODE]);
+
+	if (mode != IPVLAN_MODE_L2_MACNAT) {
+		/* TODO Probably put random address here to be presented to the
+		 * world but keep using the physical-dev addr for the outgoing
+		 * packets.
+		 */
+		eth_hw_addr_set(dev, phy_dev->dev_addr);
+	} else {
+		eth_hw_addr_random(dev);
+	}
 
 	dev->priv_flags |= IFF_NO_RX_HANDLER;
 
@@ -597,6 +689,9 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
 	port = ipvlan_port_get_rtnl(phy_dev);
 	ipvlan->port = port;
 
+	if (data && data[IFLA_IPVLAN_FLAGS])
+		port->flags = nla_get_u16(data[IFLA_IPVLAN_FLAGS]);
+
 	/* If the port-id base is at the MAX value, then wrap it around and
 	 * begin from 0x1 again. This may be due to a busy system where lots
 	 * of slaves are getting created and deleted.
@@ -625,19 +720,13 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
 	if (err)
 		goto remove_ida;
 
-	/* Flags are per port and latest update overrides. User has
-	 * to be consistent in setting it just like the mode attribute.
-	 */
-	if (data && data[IFLA_IPVLAN_FLAGS])
-		port->flags = nla_get_u16(data[IFLA_IPVLAN_FLAGS]);
-
-	if (data && data[IFLA_IPVLAN_MODE])
-		mode = nla_get_u16(data[IFLA_IPVLAN_MODE]);
-
 	err = ipvlan_set_port_mode(port, mode, extack);
 	if (err)
 		goto unlink_netdev;
 
+	if (ipvlan_is_macnat(port))
+		dev_set_allmulti(dev, 1);
+
 	list_add_tail_rcu(&ipvlan->pnode, &port->ipvlans);
 	netif_stacked_transfer_operstate(phy_dev, dev);
 	return 0;
@@ -657,6 +746,9 @@ void ipvlan_link_delete(struct net_device *dev, struct list_head *head)
 	struct ipvl_dev *ipvlan = netdev_priv(dev);
 	struct ipvl_addr *addr, *next;
 
+	if (ipvlan_is_macnat(ipvlan->port))
+		dev_set_allmulti(dev, -1);
+
 	spin_lock_bh(&ipvlan->addrs_lock);
 	list_for_each_entry_safe(addr, next, &ipvlan->addrs, anode) {
 		ipvlan_ht_addr_del(addr);
@@ -793,6 +885,9 @@ static int ipvlan_device_event(struct notifier_block *unused,
 		break;
 
 	case NETDEV_CHANGEADDR:
+		if (ipvlan_is_macnat(port))
+			break;
+
 		list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
 			eth_hw_addr_set(ipvlan->dev, dev->dev_addr);
 			call_netdevice_notifiers(NETDEV_CHANGEADDR, ipvlan->dev);
@@ -813,7 +908,7 @@ static int ipvlan_device_event(struct notifier_block *unused,
 }
 
 /* the caller must held the addrs lock */
-static int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6)
+int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6)
 {
 	struct ipvl_addr *addr;
 
@@ -822,6 +917,7 @@ static int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6)
 		return -ENOMEM;
 
 	addr->master = ipvlan;
+	addr->tstamp = get_jiffies_64();
 	if (!is_v6) {
 		memcpy(&addr->ip4addr, iaddr, sizeof(struct in_addr));
 		addr->atype = IPVL_IPV4;
@@ -928,6 +1024,9 @@ static int ipvlan_addr6_validator_event(struct notifier_block *unused,
 	if (!ipvlan_is_valid_dev(dev))
 		return NOTIFY_DONE;
 
+	if (ipvlan_is_macnat(ipvlan->port))
+		return notifier_from_errno(-EADDRNOTAVAIL);
+
 	switch (event) {
 	case NETDEV_UP:
 		if (ipvlan_addr_busy(ipvlan->port, &i6vi->i6vi_addr, true)) {
@@ -999,6 +1098,9 @@ static int ipvlan_addr4_validator_event(struct notifier_block *unused,
 	if (!ipvlan_is_valid_dev(dev))
 		return NOTIFY_DONE;
 
+	if (ipvlan_is_macnat(ipvlan->port))
+		return notifier_from_errno(-EADDRNOTAVAIL);
+
 	switch (event) {
 	case NETDEV_UP:
 		if (ipvlan_addr_busy(ipvlan->port, &ivi->ivi_addr, false)) {
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 3b491d96e52e..64ecb1d739d0 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -1269,6 +1269,7 @@ enum ipvlan_mode {
 	IPVLAN_MODE_L2 = 0,
 	IPVLAN_MODE_L3,
 	IPVLAN_MODE_L3S,
+	IPVLAN_MODE_L2_MACNAT,
 	IPVLAN_MODE_MAX
 };
 
-- 
2.25.1

Re: [PATCH net-next 01/14] ipvlan: Preparation to support mac-nat

[Bagas Sanjaya]

[-- Attachment #1: Type: text/plain, Size: 245 bytes --]

On Wed, Nov 05, 2025 at 07:14:37PM +0300, Dmitry Skorodumov wrote:
> +4.4 L2_MACNAT mode:
> +-------------

Please match section underline length to the heading text.

Thanks.

-- 
An old man doll... just what I always wanted! - Clara

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH net-next 01/14] ipvlan: Preparation to support mac-nat

[kernel test robot]

Hi Dmitry,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Dmitry-Skorodumov/ipvlan-Preparation-to-support-mac-nat/20251106-004449
base:   net-next/main
patch link:    https://lore.kernel.org/r/20251105161450.1730216-2-skorodumov.dmitry%40huawei.com
patch subject: [PATCH net-next 01/14] ipvlan: Preparation to support mac-nat
config: s390-randconfig-001-20251107 (https://download.01.org/0day-ci/archive/20251107/202511070917.SA9qQyy5-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251107/202511070917.SA9qQyy5-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511070917.SA9qQyy5-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/net/ipvlan/ipvlan_core.c:435:13: warning: 'is_ipv6_usable' defined but not used [-Wunused-function]
    static bool is_ipv6_usable(const struct in6_addr *addr)
                ^~~~~~~~~~~~~~

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for OF_GPIO
   Depends on [n]: GPIOLIB [=y] && OF [=y] && HAS_IOMEM [=n]
   Selected by [m]:
   - REGULATOR_RT5133 [=m] && REGULATOR [=y] && I2C [=m] && GPIOLIB [=y] && OF [=y]


vim +/is_ipv6_usable +435 drivers/net/ipvlan/ipvlan_core.c

   434	
 > 435	static bool is_ipv6_usable(const struct in6_addr *addr)
   436	{
   437		return !ipv6_addr_is_multicast(addr) && !ipv6_addr_loopback(addr) &&
   438		       !ipv6_addr_any(addr);
   439	}
   440	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[syzbot ci] Re: ipvlan: support mac-nat mode

[syzbot ci]

syzbot ci has tested the following series

[v3] ipvlan: support mac-nat mode
https://lore.kernel.org/all/20251105161450.1730216-1-skorodumov.dmitry@huawei.com
* [PATCH net-next 01/14] ipvlan: Preparation to support mac-nat
* [PATCH net-next 02/14] ipvlan: Send mcasts out directly in ipvlan_xmit_mode_l2()
* [PATCH net-next 03/14] ipvlan: Handle rx mcast-ip and unicast eth
* [PATCH net-next 04/14] ipvlan: Added some kind of MAC NAT
* [PATCH net-next 05/14] ipvlan: Forget all IP when device goes down
* [PATCH net-next 06/14] ipvlan: Support GSO for port -> ipvlan
* [PATCH net-next 07/14] ipvlan: Support IPv6 for learnable l2-bridge
* [PATCH net-next 08/14] ipvlan: Make the addrs_lock be per port
* [PATCH net-next 09/14] ipvlan: Take addr_lock in ipvlan_open()
* [PATCH net-next 10/14] ipvlan: Don't allow children to use IPs of main
* [PATCH net-next 11/14] ipvlan: const-specifier for functions that use iaddr
* [PATCH net-next 12/14] ipvlan: Common code from v6/v4 validator_event
* [PATCH net-next 13/14] ipvlan: common code to handle ipv6/ipv4 address events
* [PATCH net-next 14/14] ipvlan: Ignore PACKET_LOOPBACK in handle_mode_l2()

and found the following issue:
WARNING: suspicious RCU usage in ipvlan_init

Full report is available here:
https://ci.syzbot.org/series/349ca33e-4ae2-4720-9a69-17a2a9e17107

***

WARNING: suspicious RCU usage in ipvlan_init

tree:      net-next
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net-next.git
base:      01cc760632b875c4ad0d8fec0b0c01896b8a36d4
arch:      amd64
compiler:  Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config:    https://ci.syzbot.org/builds/d6598a0d-2fcb-499d-95fc-30c5096555dc/config

batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
hsr_slave_0: entered promiscuous mode
hsr_slave_1: entered promiscuous mode
=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
./include/linux/inetdevice.h:239 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor/6496:
 #0: ffffffff8ea2f980 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250
 #1: ffffffff8f2cb3c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8e9/0x1c80

stack backtrace:
CPU: 1 UID: 0 PID: 6496 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 lockdep_rcu_suspicious+0x140/0x1d0
 ipvlan_init+0xff2/0x1260
 register_netdevice+0x6bf/0x1ae0
 ipvlan_link_new+0x57a/0xc70
 rtnl_newlink_create+0x310/0xb00
 rtnl_newlink+0x16e4/0x1c80
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f114c590e03
Code: 64 89 02 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 80 3d 61 77 22 00 00 41 89 ca 74 14 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 75 c3 0f 1f 40 00 55 48 83 ec 30 44 89 4c 24
RSP: 002b:00007ffecaf08958 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f114d314620 RCX: 00007f114c590e03
RDX: 0000000000000058 RSI: 00007f114d314670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffecaf08974 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f114d314670 R15: 0000000000000000
 </TASK>

=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
drivers/net/ipvlan/ipvlan_main.c:238 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor/6496:
 #0: ffffffff8ea2f980 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250
 #1: ffffffff8f2cb3c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8e9/0x1c80

stack backtrace:
CPU: 0 UID: 0 PID: 6496 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 lockdep_rcu_suspicious+0x140/0x1d0
 ipvlan_init+0x1025/0x1260
 register_netdevice+0x6bf/0x1ae0
 ipvlan_link_new+0x57a/0xc70
 rtnl_newlink_create+0x310/0xb00
 rtnl_newlink+0x16e4/0x1c80
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f114c590e03
Code: 64 89 02 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 80 3d 61 77 22 00 00 41 89 ca 74 14 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 75 c3 0f 1f 40 00 55 48 83 ec 30 44 89 4c 24
RSP: 002b:00007ffecaf08958 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f114d314620 RCX: 00007f114c590e03
RDX: 0000000000000058 RSI: 00007f114d314670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffecaf08974 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f114d314670 R15: 0000000000000000
 </TASK>


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

[PATCH net-next 01/14] ipvlan: Preparation to support mac-nat

[Dmitry Skorodumov]

Now it is possible to create link in L2_MACNAT mode. In this patch
it is just a learnable bridge: the IPs of slaves are learned
from TX-packets of child interfaces. But in later patches
it will be extended also to collect MAC-addresses for translation.

Also, dev_add_pack() protocol is attached to the main port
to support communication from main to child interfaces.

This mode is intended for the desktop virtual machines, for
bridging to Wireless interfaces.

The mode should be specified while creating first child interface.
It is not possible to change it after this.

The maximum number of addresses on child interface is limited.
There can be IPVLAN_MAX_MACNAT_ADDRS of each (ipv4/ipv6) types.

Signed-off-by: Dmitry Skorodumov <skorodumov.dmitry@huawei.com>
---
 Documentation/networking/ipvlan.rst |  11 ++
 drivers/net/ipvlan/ipvlan.h         |  25 ++++
 drivers/net/ipvlan/ipvlan_core.c    | 196 +++++++++++++++++++++++++---
 drivers/net/ipvlan/ipvlan_main.c    | 138 +++++++++++++++++---
 include/uapi/linux/if_link.h        |   1 +
 5 files changed, 337 insertions(+), 34 deletions(-)

diff --git a/Documentation/networking/ipvlan.rst b/Documentation/networking/ipvlan.rst
index 895d0ccfd596..e1a15ae87bdf 100644
--- a/Documentation/networking/ipvlan.rst
+++ b/Documentation/networking/ipvlan.rst
@@ -90,6 +90,17 @@ works in this mode and hence it is L3-symmetric (L3s). This will have slightly l
 performance but that shouldn't matter since you are choosing this mode over plain-L3
 mode to make conn-tracking work.
 
+4.4 L2_MACNAT mode:
+-------------
+
+This mode is an extension for the L2 mode. It is primarily intended for
+desktop virtual machines for bridging to Wireless interfaces. In plain L2
+mode you have to configure IPs on slave interface to make it possible
+mux-ing frames between slaves/master. In the L2_MACNAT mode, ipvlan will
+learn itself IPv4/IPv6 address from outgoing packets. Moreover,
+the dev_add_pack() is configured on master interface to capture
+outgoing frames and mux-ing it to slave interfaces, if needed.
+
 5. Mode flags:
 ==============
 
diff --git a/drivers/net/ipvlan/ipvlan.h b/drivers/net/ipvlan/ipvlan.h
index 50de3ee204db..9db92ee11999 100644
--- a/drivers/net/ipvlan/ipvlan.h
+++ b/drivers/net/ipvlan/ipvlan.h
@@ -39,6 +39,8 @@
 
 #define IPVLAN_QBACKLOG_LIMIT	1000
 
+#define IPVLAN_MAX_MACNAT_ADDRS	4
+
 typedef enum {
 	IPVL_IPV6 = 0,
 	IPVL_ICMPV6,
@@ -83,6 +85,7 @@ struct ipvl_addr {
 	struct hlist_node	hlnode;  /* Hash-table linkage */
 	struct list_head	anode;   /* logical-interface linkage */
 	ipvl_hdr_type		atype;
+	u64			tstamp;
 	struct rcu_head		rcu;
 };
 
@@ -91,6 +94,7 @@ struct ipvl_port {
 	possible_net_t		pnet;
 	struct hlist_head	hlhead[IPVLAN_HASH_SIZE];
 	struct list_head	ipvlans;
+	struct packet_type	ipvl_ptype;
 	u16			mode;
 	u16			flags;
 	u16			dev_id_start;
@@ -103,6 +107,7 @@ struct ipvl_port {
 
 struct ipvl_skb_cb {
 	bool tx_pkt;
+	void *mark;
 };
 #define IPVL_SKB_CB(_skb) ((struct ipvl_skb_cb *)&((_skb)->cb[0]))
 
@@ -151,12 +156,32 @@ static inline void ipvlan_clear_vepa(struct ipvl_port *port)
 	port->flags &= ~IPVLAN_F_VEPA;
 }
 
+static inline bool ipvlan_is_macnat(struct ipvl_port *port)
+{
+	return port->mode == IPVLAN_MODE_L2_MACNAT;
+}
+
+static inline void ipvlan_mark_skb(struct sk_buff *skb, struct net_device *dev)
+{
+	IPVL_SKB_CB(skb)->mark = dev;
+}
+
+static inline bool ipvlan_is_skb_marked(struct sk_buff *skb,
+					struct net_device *dev)
+{
+	return (IPVL_SKB_CB(skb)->mark == dev);
+}
+
 void ipvlan_init_secret(void);
 unsigned int ipvlan_mac_hash(const unsigned char *addr);
 rx_handler_result_t ipvlan_handle_frame(struct sk_buff **pskb);
+void ipvlan_skb_crossing_ns(struct sk_buff *skb, struct net_device *dev);
 void ipvlan_process_multicast(struct work_struct *work);
+void ipvlan_multicast_enqueue(struct ipvl_port *port,
+			      struct sk_buff *skb, bool tx_pkt);
 int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev);
 void ipvlan_ht_addr_add(struct ipvl_dev *ipvlan, struct ipvl_addr *addr);
+int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6);
 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);
diff --git a/drivers/net/ipvlan/ipvlan_core.c b/drivers/net/ipvlan/ipvlan_core.c
index d7e3ddbcab6f..06c1c4fdc4f6 100644
--- a/drivers/net/ipvlan/ipvlan_core.c
+++ b/drivers/net/ipvlan/ipvlan_core.c
@@ -284,6 +284,18 @@ void ipvlan_process_multicast(struct work_struct *work)
 		rcu_read_unlock();
 
 		if (tx_pkt) {
+			if (ipvlan_is_macnat(port)) {
+				/* Inject packet to main dev */
+				nskb = skb_clone(skb, GFP_ATOMIC);
+				if (nskb) {
+					local_bh_disable();
+					nskb->pkt_type = pkt_type;
+					nskb->dev = port->dev;
+					dev_forward_skb(port->dev, nskb);
+					local_bh_enable();
+				}
+			}
+
 			/* If the packet originated here, send it out. */
 			skb->dev = port->dev;
 			skb->pkt_type = pkt_type;
@@ -299,7 +311,7 @@ void ipvlan_process_multicast(struct work_struct *work)
 	}
 }
 
-static void ipvlan_skb_crossing_ns(struct sk_buff *skb, struct net_device *dev)
+void ipvlan_skb_crossing_ns(struct sk_buff *skb, struct net_device *dev)
 {
 	bool xnet = true;
 
@@ -414,6 +426,107 @@ struct ipvl_addr *ipvlan_addr_lookup(struct ipvl_port *port, void *lyr3h,
 	return addr;
 }
 
+static bool is_ipv4_usable(__be32 addr)
+{
+	return !ipv4_is_lbcast(addr) && !ipv4_is_multicast(addr) &&
+	       !ipv4_is_zeronet(addr);
+}
+
+static bool is_ipv6_usable(const struct in6_addr *addr)
+{
+	return !ipv6_addr_is_multicast(addr) && !ipv6_addr_loopback(addr) &&
+	       !ipv6_addr_any(addr);
+}
+
+static void __ipvlan_addr_learn(struct ipvl_dev *ipvlan, void *addr, bool is_v6)
+{
+	const ipvl_hdr_type atype = is_v6 ? IPVL_IPV6 : IPVL_IPV4;
+	struct ipvl_addr *ipvladdr, *oldest = NULL;
+	unsigned int naddrs = 0;
+
+	spin_lock_bh(&ipvlan->addrs_lock);
+
+	if (ipvlan_addr_busy(ipvlan->port, addr, is_v6))
+		goto out_unlock;
+
+	list_for_each_entry_rcu(ipvladdr, &ipvlan->addrs, anode) {
+		if (ipvladdr->atype != atype)
+			continue;
+		naddrs++;
+		if (!oldest || time_before64(ipvladdr->tstamp, oldest->tstamp))
+			oldest = ipvladdr;
+	}
+
+	if (naddrs < IPVLAN_MAX_MACNAT_ADDRS) {
+		oldest = NULL;
+	} else {
+		ipvlan_ht_addr_del(oldest);
+		list_del_rcu(&oldest->anode);
+	}
+
+	ipvlan_add_addr(ipvlan, addr, is_v6);
+
+out_unlock:
+	spin_unlock_bh(&ipvlan->addrs_lock);
+	if (oldest)
+		kfree_rcu(oldest, rcu);
+}
+
+static void ipvlan_addr_learn(struct ipvl_dev *ipvlan, void *lyr3h,
+			      int addr_type)
+{
+	void *addr = NULL;
+	bool is_v6;
+
+	switch (addr_type) {
+#if IS_ENABLED(CONFIG_IPV6)
+	/* No need to handle IPVL_ICMPV6, it never has valid src-address. */
+	case IPVL_IPV6: {
+		struct ipv6hdr *ip6h;
+
+		ip6h = (struct ipv6hdr *)lyr3h;
+		if (!is_ipv6_usable(&ip6h->saddr))
+			return;
+		is_v6 = true;
+		addr = &ip6h->saddr;
+		break;
+	}
+#endif
+	case IPVL_IPV4: {
+		struct iphdr *ip4h;
+		__be32 *i4addr;
+
+		ip4h = (struct iphdr *)lyr3h;
+		i4addr = &ip4h->saddr;
+		if (!is_ipv4_usable(*i4addr))
+			return;
+		is_v6 = false;
+		addr = i4addr;
+		break;
+	}
+	case IPVL_ARP: {
+		struct arphdr *arph;
+		unsigned char *arp_ptr;
+		__be32 *i4addr;
+
+		arph = (struct arphdr *)lyr3h;
+		arp_ptr = (unsigned char *)(arph + 1);
+		arp_ptr += ipvlan->port->dev->addr_len;
+		i4addr = (__be32 *)arp_ptr;
+		if (!is_ipv4_usable(*i4addr))
+			return;
+		is_v6 = false;
+		addr = i4addr;
+		break;
+	}
+	default:
+		return;
+	}
+
+	if (!ipvlan_ht_addr_lookup(ipvlan->port, addr, is_v6))
+		__ipvlan_addr_learn(ipvlan, addr, is_v6);
+}
+
 static noinline_for_stack int ipvlan_process_v4_outbound(struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
@@ -561,8 +674,8 @@ static int ipvlan_process_outbound(struct sk_buff *skb)
 	return ret;
 }
 
-static void ipvlan_multicast_enqueue(struct ipvl_port *port,
-				     struct sk_buff *skb, bool tx_pkt)
+void ipvlan_multicast_enqueue(struct ipvl_port *port,
+			      struct sk_buff *skb, bool tx_pkt)
 {
 	if (skb->protocol == htons(ETH_P_PAUSE)) {
 		kfree_skb(skb);
@@ -618,15 +731,61 @@ static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
 
 static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
 {
-	const struct ipvl_dev *ipvlan = netdev_priv(dev);
-	struct ethhdr *eth = skb_eth_hdr(skb);
+	struct ipvl_dev *ipvlan;
 	struct ipvl_addr *addr;
-	void *lyr3h;
+	struct ethhdr *eth;
+	bool same_mac_addr;
 	int addr_type;
+	void *lyr3h;
+
+	ipvlan = netdev_priv(dev);
+	eth = skb_eth_hdr(skb);
+	if (ipvlan_is_macnat(ipvlan->port) &&
+	    ether_addr_equal(eth->h_source, dev->dev_addr)) {
+		/* ignore tx-packets from host */
+		goto out_drop;
+	}
+
+	same_mac_addr = ether_addr_equal(eth->h_dest, eth->h_source);
 
-	if (!ipvlan_is_vepa(ipvlan->port) &&
-	    ether_addr_equal(eth->h_dest, eth->h_source)) {
+	lyr3h = NULL;
+	if (!ipvlan_is_vepa(ipvlan->port)) {
 		lyr3h = ipvlan_get_L3_hdr(ipvlan->port, skb, &addr_type);
+
+		if (ipvlan_is_macnat(ipvlan->port)) {
+			if (lyr3h)
+				ipvlan_addr_learn(ipvlan, lyr3h, addr_type);
+			/* Mark SKB in advance */
+			skb = skb_share_check(skb, GFP_ATOMIC);
+			if (!skb)
+				return NET_XMIT_DROP;
+			ipvlan_mark_skb(skb, ipvlan->phy_dev);
+		}
+	}
+
+	if (is_multicast_ether_addr(eth->h_dest)) {
+		skb_reset_mac_header(skb);
+		ipvlan_skb_crossing_ns(skb, NULL);
+		ipvlan_multicast_enqueue(ipvlan->port, skb, true);
+		return NET_XMIT_SUCCESS;
+	}
+
+	if (ipvlan_is_vepa(ipvlan->port))
+		goto tx_phy_dev;
+
+	if (!same_mac_addr &&
+	    ether_addr_equal(eth->h_dest, ipvlan->phy_dev->dev_addr)) {
+		/* It is a packet from child with destination to main port.
+		 * Pass it to main.
+		 */
+		skb = skb_share_check(skb, GFP_ATOMIC);
+		if (!skb)
+			return NET_XMIT_DROP;
+		skb->pkt_type = PACKET_HOST;
+		skb->dev = ipvlan->phy_dev;
+		dev_forward_skb(ipvlan->phy_dev, skb);
+		return NET_XMIT_SUCCESS;
+	} else if (same_mac_addr) {
 		if (lyr3h) {
 			addr = ipvlan_addr_lookup(ipvlan->port, lyr3h, addr_type, true);
 			if (addr) {
@@ -649,16 +808,14 @@ static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
 		 */
 		dev_forward_skb(ipvlan->phy_dev, skb);
 		return NET_XMIT_SUCCESS;
-
-	} else if (is_multicast_ether_addr(eth->h_dest)) {
-		skb_reset_mac_header(skb);
-		ipvlan_skb_crossing_ns(skb, NULL);
-		ipvlan_multicast_enqueue(ipvlan->port, skb, true);
-		return NET_XMIT_SUCCESS;
 	}
 
+tx_phy_dev:
 	skb->dev = ipvlan->phy_dev;
 	return dev_queue_xmit(skb);
+out_drop:
+	consume_skb(skb);
+	return NET_XMIT_DROP;
 }
 
 int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -674,6 +831,7 @@ int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	switch(port->mode) {
 	case IPVLAN_MODE_L2:
+	case IPVLAN_MODE_L2_MACNAT:
 		return ipvlan_xmit_mode_l2(skb, dev);
 	case IPVLAN_MODE_L3:
 #ifdef CONFIG_IPVLAN_L3S
@@ -737,17 +895,22 @@ static rx_handler_result_t ipvlan_handle_mode_l2(struct sk_buff **pskb,
 	struct ethhdr *eth = eth_hdr(skb);
 	rx_handler_result_t ret = RX_HANDLER_PASS;
 
+	/* Ignore already seen packets. */
+	if (ipvlan_is_skb_marked(skb, port->dev))
+		return RX_HANDLER_PASS;
+
 	if (is_multicast_ether_addr(eth->h_dest)) {
 		if (ipvlan_external_frame(skb, port)) {
-			struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
-
 			/* External frames are queued for device local
 			 * distribution, but a copy is given to master
 			 * straight away to avoid sending duplicates later
 			 * when work-queue processes this frame. This is
 			 * achieved by returning RX_HANDLER_PASS.
 			 */
+			struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
 			if (nskb) {
+				ipvlan_mark_skb(skb, port->dev);
 				ipvlan_skb_crossing_ns(nskb, NULL);
 				ipvlan_multicast_enqueue(port, nskb, false);
 			}
@@ -770,6 +933,7 @@ rx_handler_result_t ipvlan_handle_frame(struct sk_buff **pskb)
 
 	switch (port->mode) {
 	case IPVLAN_MODE_L2:
+	case IPVLAN_MODE_L2_MACNAT:
 		return ipvlan_handle_mode_l2(pskb, port);
 	case IPVLAN_MODE_L3:
 		return ipvlan_handle_mode_l3(pskb, port);
diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 660f3db11766..4535a9ab50da 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -16,6 +16,15 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 
 	ASSERT_RTNL();
 	if (port->mode != nval) {
+		/* Don't allow switch off the learnable bridge mode.
+		 * Flags also must be set from the first port-link setup.
+		 */
+		if (port->mode == IPVLAN_MODE_L2_MACNAT ||
+		    (nval == IPVLAN_MODE_L2_MACNAT && port->count > 1)) {
+			netdev_err(port->dev, "MACNAT mode cannot be changed.\n");
+			return -EINVAL;
+		}
+
 		list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
 			flags = ipvlan->dev->flags;
 			if (nval == IPVLAN_MODE_L3 || nval == IPVLAN_MODE_L3S) {
@@ -40,7 +49,10 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 			ipvlan_l3s_unregister(port);
 		}
 		port->mode = nval;
+		if (port->mode == IPVLAN_MODE_L2_MACNAT)
+			dev_add_pack(&port->ipvl_ptype);
 	}
+
 	return 0;
 
 fail:
@@ -59,6 +71,66 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval,
 	return err;
 }
 
+static int ipvlan_port_rcv(struct sk_buff *skb, struct net_device *wdev,
+			   struct packet_type *pt, struct net_device *orig_wdev)
+{
+	struct ipvl_port *port;
+	struct ipvl_addr *addr;
+	struct ethhdr *eth;
+	int addr_type;
+	void *lyr3h;
+
+	port = container_of(pt, struct ipvl_port, ipvl_ptype);
+	/* We are interested only in outgoing packets.
+	 * rx-path is handled in rx_handler().
+	 */
+	if (skb->pkt_type != PACKET_OUTGOING ||
+	    ipvlan_is_skb_marked(skb, port->dev))
+		goto out;
+
+	skb = skb_share_check(skb, GFP_ATOMIC);
+	if (!skb)
+		goto no_mem;
+
+	/* data should point to eth-header */
+	skb_push(skb, skb->data - skb_mac_header(skb));
+	skb->dev = port->dev;
+	eth = eth_hdr(skb);
+
+	if (is_multicast_ether_addr(eth->h_dest)) {
+		ipvlan_skb_crossing_ns(skb, NULL);
+		skb->protocol = eth_type_trans(skb, skb->dev);
+		skb->pkt_type = PACKET_HOST;
+		ipvlan_mark_skb(skb, port->dev);
+		ipvlan_multicast_enqueue(port, skb, false);
+		return NET_RX_SUCCESS;
+	}
+
+	lyr3h = ipvlan_get_L3_hdr(port, skb, &addr_type);
+	if (!lyr3h)
+		goto out;
+
+	addr = ipvlan_addr_lookup(port, lyr3h, addr_type, true);
+	if (addr) {
+		struct ipvl_dev *ipvlan = addr->master;
+		int ret, len;
+
+		ipvlan_skb_crossing_ns(skb, ipvlan->dev);
+		skb->protocol = eth_type_trans(skb, skb->dev);
+		skb->pkt_type = PACKET_HOST;
+		ipvlan_mark_skb(skb, port->dev);
+		len = skb->len + ETH_HLEN;
+		ret = netif_rx(skb);
+		ipvlan_count_rx(ipvlan, len, ret == NET_RX_SUCCESS, false);
+		return NET_RX_SUCCESS;
+	}
+
+out:
+	dev_kfree_skb(skb);
+no_mem:
+	return NET_RX_DROP;
+}
+
 static int ipvlan_port_create(struct net_device *dev)
 {
 	struct ipvl_port *port;
@@ -84,6 +156,11 @@ static int ipvlan_port_create(struct net_device *dev)
 	if (err)
 		goto err;
 
+	port->ipvl_ptype.func = ipvlan_port_rcv;
+	port->ipvl_ptype.type = htons(ETH_P_ALL);
+	port->ipvl_ptype.dev = dev;
+	port->ipvl_ptype.list.prev = LIST_POISON2;
+
 	netdev_hold(dev, &port->dev_tracker, GFP_KERNEL);
 	return 0;
 
@@ -100,6 +177,8 @@ static void ipvlan_port_destroy(struct net_device *dev)
 	netdev_put(dev, &port->dev_tracker);
 	if (port->mode == IPVLAN_MODE_L3S)
 		ipvlan_l3s_unregister(port);
+	if (port->ipvl_ptype.list.prev != LIST_POISON2)
+		dev_remove_pack(&port->ipvl_ptype);
 	netdev_rx_handler_unregister(dev);
 	cancel_work_sync(&port->wq);
 	while ((skb = __skb_dequeue(&port->backlog)) != NULL) {
@@ -189,10 +268,13 @@ static int ipvlan_open(struct net_device *dev)
 	else
 		dev->flags &= ~IFF_NOARP;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(addr, &ipvlan->addrs, anode)
-		ipvlan_ht_addr_add(ipvlan, addr);
-	rcu_read_unlock();
+	/* for learnable, addresses will be obtained from tx-packets. */
+	if (!ipvlan_is_macnat(ipvlan->port)) {
+		rcu_read_lock();
+		list_for_each_entry_rcu(addr, &ipvlan->addrs, anode)
+			ipvlan_ht_addr_add(ipvlan, addr);
+		rcu_read_unlock();
+	}
 
 	return 0;
 }
@@ -581,11 +663,21 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
 	INIT_LIST_HEAD(&ipvlan->addrs);
 	spin_lock_init(&ipvlan->addrs_lock);
 
-	/* TODO Probably put random address here to be presented to the
-	 * world but keep using the physical-dev address for the outgoing
-	 * packets.
+	/* Flags are per port and latest update overrides. User has
+	 * to be consistent in setting it just like the mode attribute.
 	 */
-	eth_hw_addr_set(dev, phy_dev->dev_addr);
+	if (data && data[IFLA_IPVLAN_MODE])
+		mode = nla_get_u16(data[IFLA_IPVLAN_MODE]);
+
+	if (mode != IPVLAN_MODE_L2_MACNAT) {
+		/* TODO Probably put random address here to be presented to the
+		 * world but keep using the physical-dev addr for the outgoing
+		 * packets.
+		 */
+		eth_hw_addr_set(dev, phy_dev->dev_addr);
+	} else {
+		eth_hw_addr_random(dev);
+	}
 
 	dev->priv_flags |= IFF_NO_RX_HANDLER;
 
@@ -597,6 +689,9 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
 	port = ipvlan_port_get_rtnl(phy_dev);
 	ipvlan->port = port;
 
+	if (data && data[IFLA_IPVLAN_FLAGS])
+		port->flags = nla_get_u16(data[IFLA_IPVLAN_FLAGS]);
+
 	/* If the port-id base is at the MAX value, then wrap it around and
 	 * begin from 0x1 again. This may be due to a busy system where lots
 	 * of slaves are getting created and deleted.
@@ -625,19 +720,13 @@ int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
 	if (err)
 		goto remove_ida;
 
-	/* Flags are per port and latest update overrides. User has
-	 * to be consistent in setting it just like the mode attribute.
-	 */
-	if (data && data[IFLA_IPVLAN_FLAGS])
-		port->flags = nla_get_u16(data[IFLA_IPVLAN_FLAGS]);
-
-	if (data && data[IFLA_IPVLAN_MODE])
-		mode = nla_get_u16(data[IFLA_IPVLAN_MODE]);
-
 	err = ipvlan_set_port_mode(port, mode, extack);
 	if (err)
 		goto unlink_netdev;
 
+	if (ipvlan_is_macnat(port))
+		dev_set_allmulti(dev, 1);
+
 	list_add_tail_rcu(&ipvlan->pnode, &port->ipvlans);
 	netif_stacked_transfer_operstate(phy_dev, dev);
 	return 0;
@@ -657,6 +746,9 @@ void ipvlan_link_delete(struct net_device *dev, struct list_head *head)
 	struct ipvl_dev *ipvlan = netdev_priv(dev);
 	struct ipvl_addr *addr, *next;
 
+	if (ipvlan_is_macnat(ipvlan->port))
+		dev_set_allmulti(dev, -1);
+
 	spin_lock_bh(&ipvlan->addrs_lock);
 	list_for_each_entry_safe(addr, next, &ipvlan->addrs, anode) {
 		ipvlan_ht_addr_del(addr);
@@ -793,6 +885,9 @@ static int ipvlan_device_event(struct notifier_block *unused,
 		break;
 
 	case NETDEV_CHANGEADDR:
+		if (ipvlan_is_macnat(port))
+			break;
+
 		list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
 			eth_hw_addr_set(ipvlan->dev, dev->dev_addr);
 			call_netdevice_notifiers(NETDEV_CHANGEADDR, ipvlan->dev);
@@ -813,7 +908,7 @@ static int ipvlan_device_event(struct notifier_block *unused,
 }
 
 /* the caller must held the addrs lock */
-static int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6)
+int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6)
 {
 	struct ipvl_addr *addr;
 
@@ -822,6 +917,7 @@ static int ipvlan_add_addr(struct ipvl_dev *ipvlan, void *iaddr, bool is_v6)
 		return -ENOMEM;
 
 	addr->master = ipvlan;
+	addr->tstamp = get_jiffies_64();
 	if (!is_v6) {
 		memcpy(&addr->ip4addr, iaddr, sizeof(struct in_addr));
 		addr->atype = IPVL_IPV4;
@@ -928,6 +1024,9 @@ static int ipvlan_addr6_validator_event(struct notifier_block *unused,
 	if (!ipvlan_is_valid_dev(dev))
 		return NOTIFY_DONE;
 
+	if (ipvlan_is_macnat(ipvlan->port))
+		return notifier_from_errno(-EADDRNOTAVAIL);
+
 	switch (event) {
 	case NETDEV_UP:
 		if (ipvlan_addr_busy(ipvlan->port, &i6vi->i6vi_addr, true)) {
@@ -999,6 +1098,9 @@ static int ipvlan_addr4_validator_event(struct notifier_block *unused,
 	if (!ipvlan_is_valid_dev(dev))
 		return NOTIFY_DONE;
 
+	if (ipvlan_is_macnat(ipvlan->port))
+		return notifier_from_errno(-EADDRNOTAVAIL);
+
 	switch (event) {
 	case NETDEV_UP:
 		if (ipvlan_addr_busy(ipvlan->port, &ivi->ivi_addr, false)) {
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 3b491d96e52e..64ecb1d739d0 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -1269,6 +1269,7 @@ enum ipvlan_mode {
 	IPVLAN_MODE_L2 = 0,
 	IPVLAN_MODE_L3,
 	IPVLAN_MODE_L3S,
+	IPVLAN_MODE_L2_MACNAT,
 	IPVLAN_MODE_MAX
 };
 
-- 
2.25.1