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Commit c506653d authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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net: arp_ioctl() must hold RTNL 



Commit 941666c2 "net: RCU conversion of dev_getbyhwaddr() and
arp_ioctl()" introduced a regression, reported by Jamie Heilman.
"arp -Ds 192.168.2.41 eth0 pub" triggered the ASSERT_RTNL() assert
in pneigh_lookup()

Removing RTNL requirement from arp_ioctl() was a mistake, just revert
that part.

Reported-by: default avatarJamie Heilman <jamie@audible.transient.net>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0a0b7a5f

net/core/dev.c

+2 −1
Original line number Diff line number Diff line
@@ -749,7 +749,8 @@ EXPORT_SYMBOL(dev_get_by_index); 
 *	@ha: hardware address

 *

 *	Search for an interface by MAC address. Returns NULL if the device

 *	is not found or a pointer to the device. The caller must hold RCU

 *	is not found or a pointer to the device.

 *	The caller must hold RCU or RTNL.

 *	The returned device has not had its ref count increased

 *	and the caller must therefore be careful about locking

 *

net/ipv4/arp.c

+5 −6
Original line number Diff line number Diff line
@@ -1017,14 +1017,13 @@ static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) 
		IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;

		return 0;

	}

	if (__in_dev_get_rcu(dev)) {

		IN_DEV_CONF_SET(__in_dev_get_rcu(dev), PROXY_ARP, on);

	if (__in_dev_get_rtnl(dev)) {

		IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);

		return 0;

	}

	return -ENXIO;

}



/* must be called with rcu_read_lock() */

static int arp_req_set_public(struct net *net, struct arpreq *r,

		struct net_device *dev)

{
@@ -1233,10 +1232,10 @@ int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 
	if (!(r.arp_flags & ATF_NETMASK))

		((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =

							   htonl(0xFFFFFFFFUL);

	rcu_read_lock();

	rtnl_lock();

	if (r.arp_dev[0]) {

		err = -ENODEV;

		dev = dev_get_by_name_rcu(net, r.arp_dev);

		dev = __dev_get_by_name(net, r.arp_dev);

		if (dev == NULL)

			goto out;
@@ -1263,7 +1262,7 @@ int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg) 
		break;

	}

out:

	rcu_read_unlock();

	rtnl_unlock();

	if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))

		err = -EFAULT;

	return err;