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Re: [libvirt] [PATCH v3 4/4] util: move virtual network firwall rules into private chains



On 1/24/19 3:05 PM, Daniel P. Berrangé wrote:
The previous commit created new chains to hold the firewall rules. This
commit changes the code that creates rules to place them in the new
private chains instead of the builtin top level chains.

With two networks running, the rules in the filter table now look like

   -N LIBVIRT_FWI
   -N LIBVIRT_FWO
   -N LIBVIRT_FWX
   -N LIBVIRT_INP
   -N LIBVIRT_OUT
   -A INPUT -j LIBVIRT_INP
   -A FORWARD -j LIBVIRT_FWX
   -A FORWARD -j LIBVIRT_FWI
   -A FORWARD -j LIBVIRT_FWO
   -A OUTPUT -j LIBVIRT_OUT
   -A LIBVIRT_FWI -d 192.168.0.0/24 -o virbr0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
   -A LIBVIRT_FWI -o virbr0 -j REJECT --reject-with icmp-port-unreachable
   -A LIBVIRT_FWI -d 192.168.1.0/24 -o virbr1 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
   -A LIBVIRT_FWI -o virbr1 -j REJECT --reject-with icmp-port-unreachable
   -A LIBVIRT_FWO -s 192.168.0.0/24 -i virbr0 -j ACCEPT
   -A LIBVIRT_FWO -i virbr0 -j REJECT --reject-with icmp-port-unreachable
   -A LIBVIRT_FWO -s 192.168.1.0/24 -i virbr1 -j ACCEPT
   -A LIBVIRT_FWO -i virbr1 -j REJECT --reject-with icmp-port-unreachable
   -A LIBVIRT_FWX -i virbr0 -o virbr0 -j ACCEPT
   -A LIBVIRT_FWX -i virbr1 -o virbr1 -j ACCEPT
   -A LIBVIRT_INP -i virbr0 -p udp -m udp --dport 53 -j ACCEPT
   -A LIBVIRT_INP -i virbr0 -p tcp -m tcp --dport 53 -j ACCEPT
   -A LIBVIRT_INP -i virbr0 -p udp -m udp --dport 67 -j ACCEPT
   -A LIBVIRT_INP -i virbr0 -p tcp -m tcp --dport 67 -j ACCEPT
   -A LIBVIRT_INP -i virbr1 -p udp -m udp --dport 53 -j ACCEPT
   -A LIBVIRT_INP -i virbr1 -p tcp -m tcp --dport 53 -j ACCEPT
   -A LIBVIRT_INP -i virbr1 -p udp -m udp --dport 67 -j ACCEPT
   -A LIBVIRT_INP -i virbr1 -p tcp -m tcp --dport 67 -j ACCEPT
   -A LIBVIRT_OUT -o virbr0 -p udp -m udp --dport 68 -j ACCEPT
   -A LIBVIRT_OUT -o virbr1 -p udp -m udp --dport 68 -j ACCEPT

While in the nat table:

   -N LIBVIRT_PRT
   -A POSTROUTING -j LIBVIRT_PRT
   -A LIBVIRT_PRT -s 192.168.0.0/24 -d 224.0.0.0/24 -j RETURN
   -A LIBVIRT_PRT -s 192.168.0.0/24 -d 255.255.255.255/32 -j RETURN
   -A LIBVIRT_PRT -s 192.168.0.0/24 ! -d 192.168.0.0/24 -p tcp -j MASQUERADE --to-ports 1024-65535
   -A LIBVIRT_PRT -s 192.168.0.0/24 ! -d 192.168.0.0/24 -p udp -j MASQUERADE --to-ports 1024-65535
   -A LIBVIRT_PRT -s 192.168.0.0/24 ! -d 192.168.0.0/24 -j MASQUERADE
   -A LIBVIRT_PRT -s 192.168.1.0/24 -d 224.0.0.0/24 -j RETURN
   -A LIBVIRT_PRT -s 192.168.1.0/24 -d 255.255.255.255/32 -j RETURN
   -A LIBVIRT_PRT -s 192.168.1.0/24 ! -d 192.168.1.0/24 -p tcp -j MASQUERADE --to-ports 1024-65535
   -A LIBVIRT_PRT -s 192.168.1.0/24 ! -d 192.168.1.0/24 -p udp -j MASQUERADE --to-ports 1024-65535
   -A LIBVIRT_PRT -s 192.168.1.0/24 ! -d 192.168.1.0/24 -j MASQUERADE

And finally the mangle table:

   -N LIBVIRT_PRT
   -A POSTROUTING -j LIBVIRT_PRT
   -A LIBVIRT_PRT -o virbr0 -p udp -m udp --dport 68 -j CHECKSUM --checksum-fill
   -A LIBVIRT_PRT -o virbr1 -p udp -m udp --dport 68 -j CHECKSUM --checksum-fill

Signed-off-by: Daniel P. Berrangé <berrange redhat com>
---
  src/libvirt_private.syms                      |   1 +
  src/network/bridge_driver_linux.c             |  20 ++-
  src/util/viriptables.c                        | 123 +++++++++++-------
  src/util/viriptables.h                        |   2 +
  .../nat-default-linux.args                    |  32 ++---
  .../nat-ipv6-linux.args                       |  48 +++----
  .../nat-many-ips-linux.args                   |  60 ++++-----
  .../nat-no-dhcp-linux.args                    |  46 +++----
  .../nat-tftp-linux.args                       |  34 ++---
  .../route-default-linux.args                  |  22 ++--
  10 files changed, 222 insertions(+), 166 deletions(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index a88856557d..77fc26376d 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2075,6 +2075,7 @@ iptablesRemoveOutputFixUdpChecksum;
  iptablesRemoveTcpInput;
  iptablesRemoveUdpInput;
  iptablesRemoveUdpOutput;
+iptablesSetDeletePrivate;
  iptablesSetupPrivateChains;
diff --git a/src/network/bridge_driver_linux.c b/src/network/bridge_driver_linux.c
index 61f77f2735..1e033fa21b 100644
--- a/src/network/bridge_driver_linux.c
+++ b/src/network/bridge_driver_linux.c
@@ -34,17 +34,35 @@ VIR_LOG_INIT("network.bridge_driver_linux");
#define PROC_NET_ROUTE "/proc/net/route" -int networkPreReloadFirewallRules(bool startup ATTRIBUTE_UNUSED)
+int networkPreReloadFirewallRules(bool startup)
  {
      int ret = iptablesSetupPrivateChains();
      if (ret < 0)
          return -1;
+
+    /*
+     * If this is initial startup, and we just created the
+     * top level private chains we either
+     *
+     *   - upgraded from old libvirt
+     *   - freshly booted from clean state
+     *
+     * In the first case we must delete the old rules from
+     * the built-in chains, instead of our new private chains.
+     * In the second case it doesn't matter, since no existing
+     * rules will be present. Thus we can safely just tell it
+     * to always delete from the builin chain
+     */
+    if (startup && ret == 1) {
+        iptablesSetDeletePrivate(false);
+    }

No need for curly braces here.

      return 0;
  }
void networkPostReloadFirewallRules(bool startup ATTRIBUTE_UNUSED)
  {
+    iptablesSetDeletePrivate(true);
  }
diff --git a/src/util/viriptables.c b/src/util/viriptables.c
index 770dcf04a6..04fcc84705 100644
--- a/src/util/viriptables.c
+++ b/src/util/viriptables.c
@@ -48,6 +48,7 @@ enum {
      REMOVE
  };
+static int deletePrivate = true;

s/int/bool/

ACK

Michal


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