Commit b1beb681 authored Jul 27, 2012 by Jiri Benc Committed by David S. Miller Jul 27, 2012

net: fix rtnetlink IFF_PROMISC and IFF_ALLMULTI handling



When device flags are set using rtnetlink, IFF_PROMISC and IFF_ALLMULTI
flags are handled specially. Function dev_change_flags sets IFF_PROMISC and
IFF_ALLMULTI bits in dev->gflags according to the passed value but
do_setlink passes a result of rtnl_dev_combine_flags which takes those bits
from dev->flags.

This can be easily trigerred by doing:

tcpdump -i eth0 &
ip l s up eth0

ip sets IFF_UP flag in ifi_flags and ifi_change, which is combined with
IFF_PROMISC by rtnl_dev_combine_flags, causing __dev_change_flags to set
IFF_PROMISC in gflags.

Reported-by: Max Matveev <makc@redhat.com>
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e4c7f259

net/core/rtnetlink.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -659,6 +659,12 @@ static void set_operstate(struct net_device *dev, unsigned char transition)
		}
		}

		static unsigned int rtnl_dev_get_flags(const struct net_device *dev)
		{
		return (dev->flags & ~(IFF_PROMISC \| IFF_ALLMULTI)) \|
		(dev->gflags & (IFF_PROMISC \| IFF_ALLMULTI));
		}

		static unsigned int rtnl_dev_combine_flags(const struct net_device *dev,
		const struct ifinfomsg *ifm)
		{
		@@ -667,7 +673,7 @@ static unsigned int rtnl_dev_combine_flags(const struct net_device *dev,
		/* bugwards compatibility: ifi_change == 0 is treated as ~0 */
		if (ifm->ifi_change)
		flags = (flags & ifm->ifi_change) \|
		(dev->flags & ~ifm->ifi_change);
		(rtnl_dev_get_flags(dev) & ~ifm->ifi_change);

		return flags;
		}

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