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Subject[ 092/109] net: fix rtnetlink IFF_PROMISC and IFF_ALLMULTI handling
Date
From: Greg KH <gregkh@linuxfoundation.org>

3.4-stable review patch. If anyone has any objections, please let me know.

------------------


From: Jiri Benc <jbenc@redhat.com>

[ Upstream commit b1beb681cba5358f62e6187340660ade226a5fcc ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/rtnetlink.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -671,6 +671,12 @@ static void set_operstate(struct net_dev
}
}

+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)
{
@@ -679,7 +685,7 @@ static unsigned int rtnl_dev_combine_fla
/* 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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