netdev - [PATCH 3/3] ipvlan: set dev_id for l2 ports to generate unique IPv6 addresses

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Date:	Thu, 14 May 2015 16:56:20 +0300
From:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Cc:	Mahesh Bandewar <maheshb@...gle.com>, Jiri Benc <jbenc@...hat.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: [PATCH 3/3] ipvlan: set dev_id for l2 ports to generate unique IPv6
 addresses

All ipvlan ports use one MAC address, this way ipv6 RA tries to assign
one ipv6 address to all of them. This patch assigns unique dev_id to each
ipvlan port. This field is used instead of common FF-FE in Modified EUI-64.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
---
 Documentation/networking/ipvlan.txt |   12 +++++++++++-
 drivers/net/ipvlan/ipvlan.h         |    1 +
 drivers/net/ipvlan/ipvlan_main.c    |   20 ++++++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/ipvlan.txt b/Documentation/networking/ipvlan.txt
index cf996394e466..cb0b777bce58 100644
--- a/Documentation/networking/ipvlan.txt
+++ b/Documentation/networking/ipvlan.txt
@@ -24,7 +24,7 @@ using IProute2/ip utility.
 
 	ip link add link <master-dev> <slave-dev> type ipvlan mode { l2 | L3 }
 
-	e.g. ip link add link ipvl0 eth0 type ipvlan mode l2
+	e.g. ip link add link eth0 ipvl0 type ipvlan mode l2
 
 
 4. Operating modes:
@@ -41,6 +41,15 @@ slave device and packets are switched and queued to the master device to send
 out. In this mode the slaves will RX/TX multicast and broadcast (if applicable)
 as well.
 
+	In L2 mode slave devices receive Router Advertisements from the network
+and perform autoconfiguration as well as master device. Each port has unique
+16-bit device id which is used for filling octets 4-5 of Modified EUI-64.
+That gives 65533 addresses (FF-FE used by master, FF-FF/00-00 reserved/not used).
+
+	Also lower half of IPv6 address could be set as interface token:
+
+	ip token set ::aaaa:bbbb:cccc:dddd dev ipvl0
+
 4.2 L3 mode:
 	In this mode TX processing upto L3 happens on the stack instance attached
 to the slave device and packets are switched to the stack instance of the
@@ -105,3 +114,4 @@ namespace where L2 on the slave could be changed / misused.
 			(4) ip -4 addr add 127.0.0.1 dev lo
 			(5) ip -4 addr add $IPADDR dev ipvl1
 			(6) ip -4 route add default via $ROUTER dev ipvl1
+
diff --git a/drivers/net/ipvlan/ipvlan.h b/drivers/net/ipvlan/ipvlan.h
index 54549a6223dd..1ebab84e7a0e 100644
--- a/drivers/net/ipvlan/ipvlan.h
+++ b/drivers/net/ipvlan/ipvlan.h
@@ -95,6 +95,7 @@ struct ipvl_port {
 	struct rcu_head		rcu;
 	int			count;
 	u16			mode;
+	struct ida		ida;
 };
 
 static inline struct ipvl_port *ipvlan_port_get_rcu(const struct net_device *d)
diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 0cafd3e6f02d..dee0e8441150 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -53,6 +53,7 @@ static int ipvlan_port_create(struct net_device *dev)
 	INIT_LIST_HEAD(&port->ipvlans);
 	for (idx = 0; idx < IPVLAN_HASH_SIZE; idx++)
 		INIT_HLIST_HEAD(&port->hlhead[idx]);
+	ida_init(&port->ida);
 
 	err = netdev_rx_handler_register(dev, ipvlan_handle_frame, port);
 	if (err)
@@ -72,6 +73,7 @@ static void ipvlan_port_destroy(struct net_device *dev)
 
 	dev->priv_flags &= ~IFF_IPVLAN_MASTER;
 	netdev_rx_handler_unregister(dev);
+	ida_destroy(&port->ida);
 	kfree_rcu(port, rcu);
 }
 
@@ -484,6 +486,18 @@ static int ipvlan_link_new(struct net *src_net, struct net_device *dev,
 	 */
 	memcpy(dev->dev_addr, phy_dev->dev_addr, ETH_ALEN);
 
+	if (port->mode == IPVLAN_MODE_L2) {
+		/*
+		 * IPv6 addrconf uses it to produce unique addresses,
+		 * see function addrconf_ifid_eui48.
+		 */
+		err = ida_simple_get(&port->ida, 1, 0xFFFE, GFP_KERNEL);
+		if (err > 0)
+			dev->dev_id = err;
+		else if (err != -ENOSPC)
+			goto ipvlan_destroy_port;
+	}
+
 	dev->priv_flags |= IFF_IPVLAN_SLAVE;
 
 	port->count += 1;
@@ -518,6 +532,12 @@ static void ipvlan_link_delete(struct net_device *dev, struct list_head *head)
 			list_del(&addr->anode);
 		}
 	}
+
+	if (dev->dev_id) {
+		ida_simple_remove(&ipvlan->port->ida, dev->dev_id);
+		dev->dev_id = 0;
+	}
+
 	list_del_rcu(&ipvlan->pnode);
 	unregister_netdevice_queue(dev, head);
 	netdev_upper_dev_unlink(ipvlan->phy_dev, dev);

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