From: David Woodhouse Date: Mon, 27 Apr 2009 10:23:54 +0000 (-0700) Subject: tun: add IFF_TUN_EXCL flag to avoid opening a persistent device. X-Git-Tag: v2.6.31-rc1~330^2~542 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f85ba78068ac137fe9c1f50d25405d2783d75c77;p=pandora-kernel.git tun: add IFF_TUN_EXCL flag to avoid opening a persistent device. When creating a certain types of VPN, NetworkManager will first attempt to find an available tun device by iterating through 'vpn%d' until it finds one that isn't already busy. Then it'll set that to be persistent and owned by the otherwise unprivileged user that the VPN dæmon itself runs as. There's a race condition here -- during the period where the vpn%d device is created and we're waiting for the VPN dæmon to actually connect and use it, if we try to create _another_ device we could end up re-using the same one -- because trying to open it again doesn't get -EBUSY as it would while it's _actually_ busy. So solve this, we add an IFF_TUN_EXCL flag which causes tun_set_iff() to fail if it would be opening an existing persistent tundevice -- so that we can make sure we're getting an entirely _new_ device. Signed-off-by: David Woodhouse Signed-off-by: David S. Miller --- Reading git-diff-tree failed