firewall: add firewalld functionality to firewall plugin

Example of usage, which uses flannel for allocating IP
addresses for containers and then registers them in `trusted`
zone in firewalld:

{
  "cniVersion": "0.3.1",
  "name": "flannel-firewalld",
  "plugins": [
    {
      "name": "cbr0",
      "type": "flannel",
      "delegate": {
        "isDefaultGateway": true
      }
    },
    {
      "type": "firewall",
      "backend": "firewalld",
      "zone": "trusted"
    }
  ]
}

Fixes #114

Signed-off-by: Alban Crequy <alban@kinvolk.io>
Signed-off-by: Michal Rostecki <mrostecki@suse.com>

pkg/firewalld/firewalld.go

@@ -0,0 +1,72 @@
+// Copyright 2018 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package firewalld
+
+import (
+	"log"
+	"net"
+	"strings"
+
+	"github.com/godbus/dbus"
+)
+
+const (
+	dbusName               = "org.freedesktop.DBus"
+	dbusPath               = "/org/freedesktop/DBus"
+	dbusGetNameOwnerMethod = ".GetNameOwner"
+
+	FirewalldName            = "org.fedoraproject.FirewallD1"
+	FirewalldPath            = "/org/fedoraproject/FirewallD1"
+	FirewalldZoneInterface   = "org.fedoraproject.FirewallD1.zone"
+	FirewalldAddSourceMethod = ".addSource"
+	FirewalldRemoveSourceMethod = ".removeSource"
+
+	ErrZoneAlreadySet = "ZONE_ALREADY_SET"
+)
+
+// IsRunning checks whether firewalld is running.
+func IsRunning(conn *dbus.Conn) bool {
+	dbusObj := conn.Object(dbusName, dbusPath)
+	var res string
+	if err := dbusObj.Call(dbusName+dbusGetNameOwnerMethod, 0, FirewalldName).Store(&res); err != nil {
+		return false
+	}
+
+	return true
+}
+
+// AddSourceToZone adds a firewalld rule which assigns the given source IP
+// to the given zone.
+func AddSourceToZone(conn *dbus.Conn, source net.IP, zone string) error {
+	firewalldObj := conn.Object(FirewalldName, FirewalldPath)
+	var res string
+	if err := firewalldObj.Call(FirewalldZoneInterface+FirewalldAddSourceMethod, 0, zone, source.String()).Store(&res); err != nil {
+		if strings.Contains(err.Error(), ErrZoneAlreadySet) {
+			log.Printf("ip %v already bound to %q zone, it can mean that this address was assigned before to the another container without cleanup\n", source, zone)
+		} else {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// RemoveSourceFromZone removes firewalld rules which assigned the given source IP
+// to the given zone.
+func RemoveSourceFromZone(conn *dbus.Conn, source net.IP, zone string) error {
+	firewalldObj := conn.Object(FirewalldName, FirewalldPath)
+	var res string
+	return firewalldObj.Call(FirewalldZoneInterface+FirewalldRemoveSourceMethod, 0, zone, source.String()).Store(&res)
+}

plugins/meta/firewall/README.md

@@ -2,23 +2,41 @@
 
 ## Overview
 
-This plugin creates firewall rules to allow traffic to/from the host network interface given by "ifName".
+This plugin creates firewall rules to allow traffic to/from container IP address via the host network .
 It does not create any network interfaces and therefore does not set up connectivity by itself.
 It is only useful when used in addition to other plugins.
 
 ## Operation
 The following network configuration file
-```
+
+```json
 {
-  "name": "mynet",
+    "cniVersion": "0.3.1",
+    "name": "bridge-firewalld",
+    "plugins": [
+      {
+        "type": "bridge",
+        "bridge": "cni0",
+        "isGateway": true,
+        "ipMasq": true,
+        "ipam": {
+            "type": "host-local",
+            "subnet": "10.88.0.0/16",
+            "routes": [
+                { "dst": "0.0.0.0/0" }
+            ]
+        }
+      },
+      {
         "type": "firewall",
-  "ifName": "cni0"
+      }
+    ]
 }
 ```
 
-will allow the given interface to send/receive traffic via the host.
+will allow any IP addresses configured by earlier plugins to send/receive traffic via the host.
 
-A successful result would simply be an empty result, unless a previous plugin passed a previous result, in which case this plugin will return that verbatim.
+A successful result would simply be an empty result, unless a previous plugin passed a previous result, in which case this plugin will return that previous result.
 
 ## Backends
 

plugins/meta/firewall/firewall.go

@@ -74,7 +74,10 @@ func parseConf(data []byte) (*FirewallNetConf, error) {
 	}
 
 	// Parse previous result.
-	if conf.RawPrevResult != nil {
+	if conf.RawPrevResult == nil {
+		return nil, fmt.Errorf("missing prevResult from earlier plugin")
+	}
+
 	resultBytes, err := json.Marshal(conf.RawPrevResult)
 	if err != nil {
 		return nil, fmt.Errorf("could not serialize prevResult: %v", err)
@@ -88,7 +91,6 @@ func parseConf(data []byte) (*FirewallNetConf, error) {
 	if err != nil {
 		return nil, fmt.Errorf("could not convert result to current version: %v", err)
 	}
-	}
 
 	return &conf, nil
 }

plugins/meta/firewall/firewall_firewalld_test.go

@@ -0,0 +1,197 @@
+// Copyright 2018 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os/exec"
+	"strings"
+	"sync"
+	"syscall"
+
+	"github.com/containernetworking/cni/pkg/invoke"
+	"github.com/containernetworking/cni/pkg/skel"
+	"github.com/containernetworking/plugins/pkg/firewalld"
+	"github.com/containernetworking/plugins/pkg/ns"
+	"github.com/containernetworking/plugins/pkg/testutils"
+
+	"github.com/godbus/dbus"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+const (
+	confTmpl = `{
+  "cniVersion": "0.3.1",
+  "name": "firewalld-test",
+  "type": "firewall",
+  "backend": "firewalld",
+  "zone": "trusted",
+  "prevResult": {
+    "cniVersion": "0.3.0",
+    "interfaces": [
+      {"name": "%s", "sandbox": "%s"}
+    ],
+    "ips": [
+      {
+        "version": "4",
+        "address": "10.0.0.2/24",
+        "gateway": "10.0.0.1",
+        "interface": 0
+      }
+    ],
+    "routes": []
+  }
+}`
+	ifname = "eth0"
+)
+
+type fakeFirewalld struct {
+	zone   string
+	source string
+}
+
+func (f *fakeFirewalld) clear() {
+	f.zone = ""
+	f.source = ""
+}
+
+func (f *fakeFirewalld) AddSource(zone, source string) (string, *dbus.Error) {
+	f.zone = zone
+	f.source = source
+	return "", nil
+}
+
+func (f *fakeFirewalld) RemoveSource(zone, source string) (string, *dbus.Error) {
+	f.zone = zone
+	f.source = source
+	return "", nil
+}
+
+func spawnSessionDbus(wg *sync.WaitGroup) (string, *exec.Cmd) {
+	// Start a private D-Bus session bus
+	path, err := invoke.FindInPath("dbus-daemon", []string{
+		"/bin", "/sbin", "/usr/bin", "/usr/sbin",
+	})
+	Expect(err).NotTo(HaveOccurred())
+	cmd := exec.Command(path, "--session", "--print-address", "--nofork", "--nopidfile")
+	stdout, err := cmd.StdoutPipe()
+	Expect(err).NotTo(HaveOccurred())
+	err = cmd.Start()
+	Expect(err).NotTo(HaveOccurred())
+
+	// Wait for dbus-daemon to print the bus address
+	bytes, err := bufio.NewReader(stdout).ReadString('\n')
+	Expect(err).NotTo(HaveOccurred())
+	busAddr := strings.TrimSpace(string(bytes))
+	Expect(strings.HasPrefix(busAddr, "unix:abstract")).To(BeTrue())
+
+	var startWg sync.WaitGroup
+	wg.Add(1)
+	startWg.Add(1)
+	go func() {
+		defer GinkgoRecover()
+
+		startWg.Done()
+		err = cmd.Wait()
+		Expect(err).NotTo(HaveOccurred())
+		wg.Done()
+	}()
+
+	startWg.Wait()
+	return busAddr, cmd
+}
+
+var _ = Describe("firewalld test", func() {
+	var (
+		targetNs ns.NetNS
+		cmd      *exec.Cmd
+		conn     *dbus.Conn
+		wg       sync.WaitGroup
+		fwd      *fakeFirewalld
+		busAddr  string
+	)
+
+	BeforeEach(func() {
+		var err error
+		targetNs, err = testutils.NewNS()
+		Expect(err).NotTo(HaveOccurred())
+
+		// Start a private D-Bus session bus
+		busAddr, cmd = spawnSessionDbus(&wg)
+		conn, err = dbus.Dial(busAddr)
+		Expect(err).NotTo(HaveOccurred())
+		err = conn.Auth(nil)
+		Expect(err).NotTo(HaveOccurred())
+		err = conn.Hello()
+		Expect(err).NotTo(HaveOccurred())
+
+		// Start our fake firewalld
+		reply, err := conn.RequestName(firewalld.FirewalldName, dbus.NameFlagDoNotQueue)
+		Expect(err).NotTo(HaveOccurred())
+		Expect(reply).To(Equal(dbus.RequestNameReplyPrimaryOwner))
+
+		fwd = &fakeFirewalld{}
+		// Because firewalld D-Bus methods start with lower-case, and
+		// because in Go lower-case methods are private, we need to remap
+		// Go public methods to the D-Bus name
+		methods := map[string]string{
+			"AddSource":    "addSource",
+			"RemoveSource": "removeSource",
+		}
+		conn.ExportWithMap(fwd, methods, firewalld.FirewalldPath, firewalld.FirewalldZoneInterface)
+
+		// Make sure the plugin uses our private session bus
+		testConn = conn
+	})
+
+	AfterEach(func() {
+		_, err := conn.ReleaseName(firewalld.FirewalldName)
+		Expect(err).NotTo(HaveOccurred())
+
+		err = cmd.Process.Signal(syscall.SIGTERM)
+		Expect(err).NotTo(HaveOccurred())
+
+		wg.Wait()
+	})
+
+	It("works with a 0.3.1 config", func() {
+		Expect(firewalld.IsRunning(conn)).To(BeTrue())
+
+		conf := fmt.Sprintf(confTmpl, ifname, targetNs.Path())
+		args := &skel.CmdArgs{
+			ContainerID: "dummy",
+			Netns:       targetNs.Path(),
+			IfName:      ifname,
+			StdinData:   []byte(conf),
+		}
+		_, _, err := testutils.CmdAddWithResult(targetNs.Path(), ifname, []byte(conf), func() error {
+			return cmdAdd(args)
+		})
+		Expect(err).NotTo(HaveOccurred())
+		Expect(fwd.zone).To(Equal("trusted"))
+		Expect(fwd.source).To(Equal("10.0.0.2/32"))
+		fwd.clear()
+
+		err = testutils.CmdDelWithResult(targetNs.Path(), ifname, func() error {
+			return cmdDel(args)
+		})
+		Expect(err).NotTo(HaveOccurred())
+		Expect(fwd.zone).To(Equal("trusted"))
+		Expect(fwd.source).To(Equal("10.0.0.2/32"))
+	})
+})

plugins/meta/firewall/firewalld.go

@@ -0,0 +1,76 @@
+// Copyright 2018 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+
+	"github.com/containernetworking/plugins/pkg/firewalld"
+
+	"github.com/godbus/dbus"
+)
+
+// Only used for testcases to override the D-Bus connection
+var testConn *dbus.Conn
+
+type fwdBackend struct {
+	conn *dbus.Conn
+}
+
+// fwdBackend implements the FirewallBackend interface
+var _ FirewallBackend = &fwdBackend{}
+
+func getConn() (*dbus.Conn, error) {
+	if testConn != nil {
+		return testConn, nil
+	}
+	return dbus.SystemBus()
+}
+
+func isFirewalldRunning() bool {
+	conn, err := getConn()
+	if err != nil {
+		return false
+	}
+	return firewalld.IsRunning(conn)
+}
+
+func newFirewalldBackend(conf *FirewallNetConf) (FirewallBackend, error) {
+	conn, err := getConn()
+	if err != nil {
+		return nil, err
+	}
+
+	backend := &fwdBackend{
+		conn: conn,
+	}
+	return backend, nil
+}
+
+func (fb *fwdBackend) Add(conf *FirewallNetConf) error {
+	for _, ip := range conf.PrevResult.IPs {
+		if err := firewalld.AddSourceToZone(fb.conn, ip.Address.IP, conf.FirewalldZone); err != nil {
+			return fmt.Errorf("failed to add the address %v to %v zone: %v", ip.Address.IP, conf.FirewalldZone, err)
+		}
+	}
+	return nil
+}
+
+func (fb *fwdBackend) Del(conf *FirewallNetConf) error {
+	for _, ip := range conf.PrevResult.IPs {
+		firewalld.RemoveSourceFromZone(fb.conn, ip.Address.IP, conf.FirewalldZone)
+	}
+	return nil
+}