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753ff83a50
This bug resolves CVE-2012-3411, which is described in the following bugzilla report: https://bugzilla.redhat.com/show_bug.cgi?id=833033 The following report is specifically for libvirt on Fedora: https://bugzilla.redhat.com/show_bug.cgi?id=874702 In short, a dnsmasq instance run with the intention of listening for DHCP/DNS requests only on a libvirt virtual network (which is constructed using a Linux host bridge) would also answer queries sent from outside the virtualization host. This patch takes advantage of a new dnsmasq option "--bind-dynamic", which will cause the listening socket to be setup such that it will only receive those requests that actually come in via the bridge interface. In order for this behavior to actually occur, not only must "--bind-interfaces" be replaced with "--bind-dynamic", but also all "--listen-address" options must be replaced with a single "--interface" option. Fully: --bind-interfaces --except-interface lo --listen-address x.x.x.x ... (with --listen-address possibly repeated) is replaced with: --bind-dynamic --interface virbrX Of course libvirt can't use this new option if the host's dnsmasq doesn't have it, but we still want libvirt to function (because the great majority of libvirt installations, which only have mode='nat' networks using RFC1918 private address ranges (e.g. 192.168.122.0/24), are immune to this vulnerability from anywhere beyond the local subnet of the host), so we use the new dnsmasqCaps API to check if dnsmasq supports the new option and, if not, we use the "old" option style instead. In order to assure that this permissiveness doesn't lead to a vulnerable system, we do check for non-private addresses in this case, and refuse to start the network if both a) we are using the old-style options, and b) the network has a publicly routable IP address. Hopefully this will provide the proper balance of not being disruptive to those not practically affected, and making sure that those who *are* affected get their dnsmasq upgraded. (--bind-dynamic was added to dnsmasq in upstream commit 54dd393f3938fc0c19088fbd319b95e37d81a2b0, which was included in dnsmasq-2.63) |
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| .. | ||
| isolated-network.argv | ||
| isolated-network.xml | ||
| nat-network-dns-hosts.argv | ||
| nat-network-dns-hosts.xml | ||
| nat-network-dns-srv-record-minimal.argv | ||
| nat-network-dns-srv-record-minimal.xml | ||
| nat-network-dns-srv-record.argv | ||
| nat-network-dns-srv-record.xml | ||
| nat-network-dns-txt-record.argv | ||
| nat-network-dns-txt-record.xml | ||
| nat-network.argv | ||
| nat-network.xml | ||
| netboot-network.argv | ||
| netboot-network.xml | ||
| netboot-proxy-network.argv | ||
| netboot-proxy-network.xml | ||
| routed-network.argv | ||
| routed-network.xml | ||