From 9eb2b573253626c8c9329140d4ce2043863e417b Mon Sep 17 00:00:00 2001 From: Laine Stump Date: Thu, 13 Dec 2012 01:46:40 -0500 Subject: [PATCH] network: prevent dnsmasq from listening on localhost 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 that fixes the bug (commit d66eb7866757dd371560c288dc6201fb9348792a), 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 preserving the same options), so a cherry-pick is just one very large conflict.) --- src/network/bridge_driver.c | 8 ++++---- tests/networkxml2argvdata/isolated-network.argv | 2 +- tests/networkxml2argvdata/nat-network-dns-hosts.argv | 2 +- .../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 8010797d6c..6053770727 100644 --- a/src/network/bridge_driver.c +++ b/src/network/bridge_driver.c @@ -510,6 +510,9 @@ 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 @@ -523,10 +526,7 @@ 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 d629192e88..d91c730afc 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 e5143acbbe..431e98744f 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 c38b954979..9c26f32361 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 311b0d76f9..ff9c223bf6 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 cbdf50db9a..2b133ff9a6 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 967ca94591..1a771d0822 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 bcd6fad5d1..9f8d1146dd 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 --enable-tftp \ diff --git a/tests/networkxml2argvdata/netboot-proxy-network.argv b/tests/networkxml2argvdata/netboot-proxy-network.argv index 8c5ef9bf44..90a31e2b45 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 eacdf2d70a..862013e6c0 100644 --- a/tests/networkxml2argvdata/routed-network.argv +++ b/tests/networkxml2argvdata/routed-network.argv @@ -1,3 +1,3 @@ @DNSMASQ@ --strict-order \ --local=// --domain-needed --conf-file= \ ---bind-dynamic --interface virbr1\ +--except-interface lo --bind-dynamic --interface virbr1\