1. 31 1月, 2019 18 次提交
  2. 30 1月, 2019 20 次提交
  3. 29 1月, 2019 2 次提交
    • D
      util: move virtual network firwall rules into private chains · 7431b3eb
      Daniel P. Berrangé 提交于
      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: NDaniel P. Berrangé <berrange@redhat.com>
      7431b3eb
    • D
      util: create private chains for virtual network firewall rules · 5f1e6a7d
      Daniel P. Berrangé 提交于
      Historically firewall rules for virtual networks were added straight
      into the base chains. This works but has a number of bugs and design
      limitations:
      
        - It is inflexible for admins wanting to add extra rules ahead
          of libvirt's rules, via hook scripts.
      
        - It is not clear to the admin that the rules were created by
          libvirt
      
        - Each rule must be deleted by libvirt individually since they
          are all directly in the builtin chains
      
        - The ordering of rules in the forward chain is incorrect
          when multiple networks are created, allowing traffic to
          mistakenly flow between networks in one direction.
      
      To address all of these problems, libvirt needs to move to creating
      rules in its own private chains. In the top level builtin chains,
      libvirt will add links to its own private top level chains.
      
      Addressing the traffic ordering bug requires some extra steps. With
      everything going into the FORWARD chain there was interleaving of rules
      for outbound traffic and inbound traffic for each network:
      
        -A FORWARD -d 192.168.3.0/24 -o virbr1 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
        -A FORWARD -s 192.168.3.0/24 -i virbr1 -j ACCEPT
        -A FORWARD -i virbr1 -o virbr1 -j ACCEPT
        -A FORWARD -o virbr1 -j REJECT --reject-with icmp-port-unreachable
        -A FORWARD -i virbr1 -j REJECT --reject-with icmp-port-unreachable
        -A FORWARD -d 192.168.2.0/24 -o virbr0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
        -A FORWARD -s 192.168.2.0/24 -i virbr0 -j ACCEPT
        -A FORWARD -i virbr0 -o virbr0 -j ACCEPT
        -A FORWARD -o virbr0 -j REJECT --reject-with icmp-port-unreachable
        -A FORWARD -i virbr0 -j REJECT --reject-with icmp-port-unreachable
      
      The rule allowing outbound traffic from virbr1 would mistakenly
      allow packets from virbr1 to virbr0, before the rule denying input
      to virbr0 gets a chance to run.
      
      What we really need todo is group the forwarding rules into three
      distinct sets:
      
       * Cross rules - LIBVIRT_FWX
      
        -A FORWARD -i virbr1 -o virbr1 -j ACCEPT
        -A FORWARD -i virbr0 -o virbr0 -j ACCEPT
      
       * Incoming rules - LIBVIRT_FWI
      
        -A FORWARD -d 192.168.3.0/24 -o virbr1 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
        -A FORWARD -o virbr1 -j REJECT --reject-with icmp-port-unreachable
        -A FORWARD -d 192.168.2.0/24 -o virbr0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
        -A FORWARD -o virbr0 -j REJECT --reject-with icmp-port-unreachable
      
       * Outgoing rules - LIBVIRT_FWO
      
        -A FORWARD -s 192.168.3.0/24 -i virbr1 -j ACCEPT
        -A FORWARD -i virbr1 -j REJECT --reject-with icmp-port-unreachable
        -A FORWARD -s 192.168.2.0/24 -i virbr0 -j ACCEPT
        -A FORWARD -i virbr0 -j REJECT --reject-with icmp-port-unreachable
      
      There is thus no risk of outgoing rules for one network mistakenly
      allowing incoming traffic for another network, as all incoming rules
      are evalated first.
      
      With this in mind, we'll thus need three distinct chains linked from
      the FORWARD chain, so we end up with:
      
              INPUT --> LIBVIRT_INP   (filter)
      
             OUTPUT --> LIBVIRT_OUT   (filter)
      
            FORWARD +-> LIBVIRT_FWX   (filter)
                    +-> LIBVIRT_FWO
                    \-> LIBVIRT_FWI
      
        POSTROUTING --> LIBVIRT_PRT   (nat & mangle)
      Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>
      5f1e6a7d