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Commit e2525360 authored by Mahesh Bandewar's avatar Mahesh Bandewar Committed by David S. Miller
Browse files

ipvlan: fix multicast processing 



In an IPvlan setup when master is set in loopback mode e.g.

  ethtool -K eth0 set loopback on

  where eth0 is master device for IPvlan setup.

The failure is caused by the faulty logic that determines if the
packet is from TX-path vs. RX-path by just looking at the mac-
addresses on the packet while processing multicast packets.

In the loopback-mode where this crash was happening, the packets
that are sent out are reflected by the NIC and are processed on
the RX path, but mac-address check tricks into thinking this
packet is from TX path and falsely uses dev_forward_skb() to pass
packets to the slave (virtual) devices.

This patch records the path while queueing packets and eliminates
logic of looking at mac-addresses for the same decision.

------------[ cut here ]------------
kernel BUG at include/linux/skbuff.h:1737!
Call Trace:
 [<ffffffff921fbbc2>] dev_forward_skb+0x92/0xd0
 [<ffffffffc031ac65>] ipvlan_process_multicast+0x395/0x4c0 [ipvlan]
 [<ffffffffc031a9a7>] ? ipvlan_process_multicast+0xd7/0x4c0 [ipvlan]
 [<ffffffff91cdfea7>] ? process_one_work+0x147/0x660
 [<ffffffff91cdff09>] process_one_work+0x1a9/0x660
 [<ffffffff91cdfea7>] ? process_one_work+0x147/0x660
 [<ffffffff91ce086d>] worker_thread+0x11d/0x360
 [<ffffffff91ce0750>] ? rescuer_thread+0x350/0x350
 [<ffffffff91ce960b>] kthread+0xdb/0xe0
 [<ffffffff91c05c70>] ? _raw_spin_unlock_irq+0x30/0x50
 [<ffffffff91ce9530>] ? flush_kthread_worker+0xc0/0xc0
 [<ffffffff92348b7a>] ret_from_fork+0x9a/0xd0
 [<ffffffff91ce9530>] ? flush_kthread_worker+0xc0/0xc0

Fixes: ba35f858 ("ipvlan: Defer multicast / broadcast processing to a work-queue")
Signed-off-by: default avatarMahesh Bandewar <maheshb@google.com>
CC: Eric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b1227d01

drivers/net/ipvlan/ipvlan.h

+5 −0
Original line number Diff line number Diff line
@@ -99,6 +99,11 @@ struct ipvl_port { 
	int			count;

};



struct ipvl_skb_cb {

	bool tx_pkt;

};

#define IPVL_SKB_CB(_skb) ((struct ipvl_skb_cb *)&((_skb)->cb[0]))



static inline struct ipvl_port *ipvlan_port_get_rcu(const struct net_device *d)

{

	return rcu_dereference(d->rx_handler_data);

drivers/net/ipvlan/ipvlan_core.c

+15 −11
Original line number Diff line number Diff line
@@ -198,7 +198,7 @@ void ipvlan_process_multicast(struct work_struct *work) 
	unsigned int mac_hash;

	int ret;

	u8 pkt_type;

	bool hlocal, dlocal;

	bool tx_pkt;



	__skb_queue_head_init(&list);
@@ -211,7 +211,7 @@ void ipvlan_process_multicast(struct work_struct *work) 
		bool consumed = false;



		ethh = eth_hdr(skb);

		hlocal = ether_addr_equal(ethh->h_source, port->dev->dev_addr);

		tx_pkt = IPVL_SKB_CB(skb)->tx_pkt;

		mac_hash = ipvlan_mac_hash(ethh->h_dest);



		if (ether_addr_equal(ethh->h_dest, port->dev->broadcast))
@@ -219,13 +219,10 @@ void ipvlan_process_multicast(struct work_struct *work) 
		else

			pkt_type = PACKET_MULTICAST;



		dlocal = false;

		rcu_read_lock();

		list_for_each_entry_rcu(ipvlan, &port->ipvlans, pnode) {

			if (hlocal && (ipvlan->dev == dev)) {

				dlocal = true;

			if (tx_pkt && (ipvlan->dev == skb->dev))

				continue;

			}

			if (!test_bit(mac_hash, ipvlan->mac_filters))

				continue;

			if (!(ipvlan->dev->flags & IFF_UP))
@@ -238,7 +235,7 @@ void ipvlan_process_multicast(struct work_struct *work) 
				consumed = true;

				nskb->pkt_type = pkt_type;

				nskb->dev = ipvlan->dev;

				if (hlocal)

				if (tx_pkt)

					ret = dev_forward_skb(ipvlan->dev, nskb);

				else

					ret = netif_rx(nskb);
@@ -248,7 +245,7 @@ void ipvlan_process_multicast(struct work_struct *work) 
		}

		rcu_read_unlock();



		if (dlocal) {

		if (tx_pkt) {

			/* If the packet originated here, send it out. */

			skb->dev = port->dev;

			skb->pkt_type = pkt_type;
@@ -480,13 +477,20 @@ static int ipvlan_process_outbound(struct sk_buff *skb) 
}



static void ipvlan_multicast_enqueue(struct ipvl_port *port,

				     struct sk_buff *skb)

				     struct sk_buff *skb, bool tx_pkt)

{

	if (skb->protocol == htons(ETH_P_PAUSE)) {

		kfree_skb(skb);

		return;

	}



	/* Record that the deferred packet is from TX or RX path. By

	 * looking at mac-addresses on packet will lead to erronus decisions.

	 * (This would be true for a loopback-mode on master device or a

	 * hair-pin mode of the switch.)

	 */

	IPVL_SKB_CB(skb)->tx_pkt = tx_pkt;



	spin_lock(&port->backlog.lock);

	if (skb_queue_len(&port->backlog) < IPVLAN_QBACKLOG_LIMIT) {

		if (skb->dev)
@@ -549,7 +553,7 @@ static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev) 


	} else if (is_multicast_ether_addr(eth->h_dest)) {

		ipvlan_skb_crossing_ns(skb, NULL);

		ipvlan_multicast_enqueue(ipvlan->port, skb);

		ipvlan_multicast_enqueue(ipvlan->port, skb, true);

		return NET_XMIT_SUCCESS;

	}
@@ -646,7 +650,7 @@ static rx_handler_result_t ipvlan_handle_mode_l2(struct sk_buff **pskb, 
			 */

			if (nskb) {

				ipvlan_skb_crossing_ns(nskb, NULL);

				ipvlan_multicast_enqueue(port, nskb);

				ipvlan_multicast_enqueue(port, nskb, false);

			}

		}

	} else {