[libvirt] [PATCH v0.10.2-maint] network: prevent dnsmasq from listening on localhost

(I'm sending this v0.10.2-maint "backport" of the upstream patch to the list because the code in question was completely replaced, so it required a new patch rather than a backport. The backport for 0.9.11-maint is nearly identical to this, so I won't be sending that one) This patch resolves the problem reported in: https://bugzilla.redhat.com/show_bug.cgi?id=886663 The source of the problem was the fix for CVE 2011-3411: https://bugzilla.redhat.com/show_bug.cgi?id=833033 which was originally committed upstream in commit 753ff83a50263d6975f88d6605d4b5ddfcc97560. That commit improperly removed the "--except-interface lo" from dnsmasq commandlines when --bind-dynamic was used (based on comments in the latter bug). It turns out that the problem reported in the CVE could be eliminated without removing "--except-interface lo", and removing it actually caused each instance of dnsmasq to listen on localhost on port 53, which created a new problem: If another instance of dnsmasq using "--bind-interfaces" (instead of "--bind-dynamic") had already been started (or if another instance started later used "--bind-dynamic"), this wouldn't have any immediately visible ill effects, but if you tried to start another dnsmasq instance using "--bind-interfaces" *after* starting any libvirt networks, the new dnsmasq would fail to start, because there was already another process listening on port 53. This patch changes the network driver to *always* add "--except-interface lo" to dnsmasq conf files, regardless of whether we use bind-dynamic or bind-interfaces. This way no libvirt dnsmasq instances are listening on localhost (and the CVE is still fixed). The actual code change is miniscule, but must be propogated through all of the test files as well. (This is *not* a cherry-pick of the upstream commit, because subsequent to the CVE fix, another patch changed the network driver to put dnsmasq options in a conf file rather than directly on the dnsmasq commandline, but preserved the same options.) --- src/network/bridge_driver.c | 8 ++++---- tests/networkxml2argvdata/isolated-network.argv | 2 +- tests/networkxml2argvdata/nat-network-dns-hosts.argv | 2 +- tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv | 2 +- tests/networkxml2argvdata/nat-network-dns-srv-record.argv | 2 +- tests/networkxml2argvdata/nat-network-dns-txt-record.argv | 2 +- tests/networkxml2argvdata/nat-network.argv | 2 +- tests/networkxml2argvdata/netboot-network.argv | 2 +- tests/networkxml2argvdata/netboot-proxy-network.argv | 2 +- tests/networkxml2argvdata/routed-network.argv | 2 +- 10 files changed, 13 insertions(+), 13 deletions(-) diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c index 1fa7cd0..ff11364 100644 --- a/src/network/bridge_driver.c +++ b/src/network/bridge_driver.c @@ -672,6 +672,9 @@ networkBuildDnsmasqArgv(virNetworkObjPtr network, /* *no* conf file */ virCommandAddArg(cmd, "--conf-file="); + /* dnsmasq will *always* listen on localhost unless told otherwise */ + virCommandAddArgList(cmd, "--except-interface", "lo", NULL); + if (dnsmasqCapsGet(caps, DNSMASQ_CAPS_BIND_DYNAMIC)) { /* using --bind-dynamic with only --interface (no * --listen-address) prevents dnsmasq from responding to dns @@ -685,10 +688,7 @@ networkBuildDnsmasqArgv(virNetworkObjPtr network, "--interface", network->def->bridge, NULL); } else { - virCommandAddArgList(cmd, - "--bind-interfaces", - "--except-interface", "lo", - NULL); + virCommandAddArg(cmd, "--bind-interfaces"); /* * --interface does not actually work with dnsmasq < 2.47, * due to DAD for ipv6 addresses on the interface. diff --git a/tests/networkxml2argvdata/isolated-network.argv b/tests/networkxml2argvdata/isolated-network.argv index 3d8601e..861fd74 100644 --- a/tests/networkxml2argvdata/isolated-network.argv +++ b/tests/networkxml2argvdata/isolated-network.argv @@ -1,6 +1,6 @@ @DNSMASQ@ --strict-order \ --local=// --domain-needed --conf-file= \ ---bind-interfaces --except-interface lo \ +--except-interface lo --bind-interfaces \ --listen-address 192.168.152.1 \ --dhcp-option=3 --no-resolv \ --dhcp-range 192.168.152.2,192.168.152.254 \ diff --git a/tests/networkxml2argvdata/nat-network-dns-hosts.argv b/tests/networkxml2argvdata/nat-network-dns-hosts.argv index e5143ac..431e987 100644 --- a/tests/networkxml2argvdata/nat-network-dns-hosts.argv +++ b/tests/networkxml2argvdata/nat-network-dns-hosts.argv @@ -1,5 +1,5 @@ @DNSMASQ@ --strict-order --domain=example.com \ --local=/example.com/ --domain-needed \ --conf-file= \ ---bind-dynamic --interface virbr0 \ +--except-interface lo --bind-dynamic --interface virbr0 \ --expand-hosts --addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts\ diff --git a/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv b/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv index 031da3f..24d88ad 100644 --- a/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv +++ b/tests/networkxml2argvdata/nat-network-dns-srv-record-minimal.argv @@ -1,7 +1,7 @@ @DNSMASQ@ \ --strict-order \ --local=// --domain-needed --conf-file= \ ---bind-interfaces --except-interface lo \ +--except-interface lo --bind-interfaces \ --listen-address 192.168.122.1 \ --listen-address 192.168.123.1 \ --listen-address fc00:db8:ac10:fe01::1 \ diff --git a/tests/networkxml2argvdata/nat-network-dns-srv-record.argv b/tests/networkxml2argvdata/nat-network-dns-srv-record.argv index beff591..f417af8 100644 --- a/tests/networkxml2argvdata/nat-network-dns-srv-record.argv +++ b/tests/networkxml2argvdata/nat-network-dns-srv-record.argv @@ -1,7 +1,7 @@ @DNSMASQ@ \ --strict-order \ --local=// --domain-needed --conf-file= \ ---bind-dynamic --interface virbr0 \ +--except-interface lo --bind-dynamic --interface virbr0 \ --srv-host=name.tcp.test-domain-name,.,1024,10,10 \ --dhcp-range 192.168.122.2,192.168.122.254 \ --dhcp-leasefile=/var/lib/libvirt/dnsmasq/default.leases \ diff --git a/tests/networkxml2argvdata/nat-network-dns-txt-record.argv b/tests/networkxml2argvdata/nat-network-dns-txt-record.argv index fc164f6..86b7ba3 100644 --- a/tests/networkxml2argvdata/nat-network-dns-txt-record.argv +++ b/tests/networkxml2argvdata/nat-network-dns-txt-record.argv @@ -1,6 +1,6 @@ @DNSMASQ@ --strict-order \ --local=// --domain-needed --conf-file= \ ---bind-dynamic --interface virbr0 \ +--except-interface lo --bind-dynamic --interface virbr0 \ '--txt-record=example,example value' \ --dhcp-range 192.168.122.2,192.168.122.254 \ --dhcp-leasefile=/var/lib/libvirt/dnsmasq/default.leases \ diff --git a/tests/networkxml2argvdata/nat-network.argv b/tests/networkxml2argvdata/nat-network.argv index 6303f76..8a540d5 100644 --- a/tests/networkxml2argvdata/nat-network.argv +++ b/tests/networkxml2argvdata/nat-network.argv @@ -1,6 +1,6 @@ @DNSMASQ@ --strict-order \ --local=// --domain-needed --conf-file= \ ---bind-dynamic --interface virbr0 \ +--except-interface lo --bind-dynamic --interface virbr0 \ --dhcp-range 192.168.122.2,192.168.122.254 \ --dhcp-leasefile=/var/lib/libvirt/dnsmasq/default.leases \ --dhcp-lease-max=253 --dhcp-no-override \ diff --git a/tests/networkxml2argvdata/netboot-network.argv b/tests/networkxml2argvdata/netboot-network.argv index 9699e5c..0e17a71 100644 --- a/tests/networkxml2argvdata/netboot-network.argv +++ b/tests/networkxml2argvdata/netboot-network.argv @@ -1,6 +1,6 @@ @DNSMASQ@ --strict-order --domain=example.com \ --local=/example.com/ --domain-needed --conf-file= \ ---bind-interfaces --except-interface lo --listen-address 192.168.122.1 \ +--except-interface lo --bind-interfaces --listen-address 192.168.122.1 \ --dhcp-range 192.168.122.2,192.168.122.254 \ --dhcp-leasefile=/var/lib/libvirt/dnsmasq/netboot.leases \ --dhcp-lease-max=253 --dhcp-no-override --expand-hosts \ diff --git a/tests/networkxml2argvdata/netboot-proxy-network.argv b/tests/networkxml2argvdata/netboot-proxy-network.argv index 9ac3018..8764ef5 100644 --- a/tests/networkxml2argvdata/netboot-proxy-network.argv +++ b/tests/networkxml2argvdata/netboot-proxy-network.argv @@ -1,6 +1,6 @@ @DNSMASQ@ --strict-order --domain=example.com \ --local=/example.com/ --domain-needed --conf-file= \ ---bind-interfaces --except-interface lo \ +--except-interface lo --bind-interfaces \ --listen-address 192.168.122.1 \ --dhcp-range 192.168.122.2,192.168.122.254 \ --dhcp-leasefile=/var/lib/libvirt/dnsmasq/netboot.leases \ diff --git a/tests/networkxml2argvdata/routed-network.argv b/tests/networkxml2argvdata/routed-network.argv index 700c904..3221f65 100644 --- a/tests/networkxml2argvdata/routed-network.argv +++ b/tests/networkxml2argvdata/routed-network.argv @@ -1,4 +1,4 @@ @DNSMASQ@ --strict-order \ --local=// --domain-needed --conf-file= \ ---bind-dynamic --interface virbr1 \ +--except-interface lo --bind-dynamic --interface virbr1 \ --addn-hosts=/var/lib/libvirt/dnsmasq/local.addnhosts\ -- 1.7.11.7