Inspect network info of a joined network namespace

Closes: https://github.com/containers/podman/issues/13150
Signed-off-by: 😎 Mostafa Emami <mustafaemami@gmail.com>

libpod/networking_linux.go

@@ -30,6 +30,7 @@ import (
 	"github.com/containers/podman/v4/pkg/util"
 	"github.com/containers/podman/v4/utils"
 	"github.com/containers/storage/pkg/lockfile"
+	spec "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/opencontainers/selinux/go-selinux/label"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -990,8 +991,20 @@ func (c *Container) getContainerNetworkInfo() (*define.InspectNetworkSettings, e
 		return nil, err
 	}
 
-	// We can't do more if the network is down.
 	if c.state.NetNS == nil {
+		if networkNSPath := c.joinedNetworkNSPath(); networkNSPath != "" {
+			if result, err := c.inspectJoinedNetworkNS(networkNSPath); err == nil {
+				if basicConfig, err := resultToBasicNetworkConfig(result); err == nil {
+					// fallback to dummy configuration
+					settings.InspectBasicNetworkConfig = basicConfig
+					return settings, nil
+				}
+			}
+			// do not propagate error inspecting a joined network ns
+			logrus.Errorf("Error inspecting network namespace: %s of container %s: %v", networkNSPath, c.ID(), err)
+		}
+		// We can't do more if the network is down.
+
 		// We still want to make dummy configurations for each CNI net
 		// the container joined.
 		if len(networks) > 0 {
@@ -1065,11 +1078,84 @@ func (c *Container) getContainerNetworkInfo() (*define.InspectNetworkSettings, e
 	return settings, nil
 }
 
+func (c *Container) joinedNetworkNSPath() string {
+	for _, namespace := range c.config.Spec.Linux.Namespaces {
+		if namespace.Type == spec.NetworkNamespace {
+			return namespace.Path
+		}
+	}
+	return ""
+}
+
+func (c *Container) inspectJoinedNetworkNS(networkns string) (q types.StatusBlock, retErr error) {
+	var result types.StatusBlock
+	err := ns.WithNetNSPath(networkns, func(_ ns.NetNS) error {
+		ifaces, err := net.Interfaces()
+		if err != nil {
+			return err
+		}
+		routes, err := netlink.RouteList(nil, netlink.FAMILY_ALL)
+		if err != nil {
+			return err
+		}
+		var gateway net.IP
+		for _, route := range routes {
+			// default gateway
+			if route.Dst == nil {
+				gateway = route.Gw
+			}
+		}
+		result.Interfaces = make(map[string]types.NetInterface)
+		for _, iface := range ifaces {
+			if iface.Flags&net.FlagLoopback != 0 {
+				continue
+			}
+			addrs, err := iface.Addrs()
+			if err != nil {
+				continue
+			}
+			if len(addrs) == 0 {
+				continue
+			}
+			subnets := make([]types.NetAddress, 0, len(addrs))
+			for _, address := range addrs {
+				if ipnet, ok := address.(*net.IPNet); ok {
+					if ipnet.IP.IsLinkLocalMulticast() || ipnet.IP.IsLinkLocalUnicast() {
+						continue
+					}
+					subnet := types.NetAddress{
+						IPNet: types.IPNet{
+							IPNet: *ipnet,
+						},
+					}
+					if ipnet.Contains(gateway) {
+						subnet.Gateway = gateway
+					}
+					subnets = append(subnets, subnet)
+				}
+			}
+			result.Interfaces[iface.Name] = types.NetInterface{
+				Subnets:    subnets,
+				MacAddress: types.HardwareAddr(iface.HardwareAddr),
+			}
+		}
+		return nil
+	})
+	return result, err
+}
+
 // resultToBasicNetworkConfig produces an InspectBasicNetworkConfig from a CNI
 // result
 func resultToBasicNetworkConfig(result types.StatusBlock) (define.InspectBasicNetworkConfig, error) {
 	config := define.InspectBasicNetworkConfig{}
-	for _, netInt := range result.Interfaces {
+	interfaceNames := make([]string, len(result.Interfaces))
+	for interfaceName := range result.Interfaces {
+		interfaceNames = append(interfaceNames, interfaceName)
+	}
+	// ensure consistent inspect results by sorting
+	sort.Strings(interfaceNames)
+	for _, interfaceName := range interfaceNames {
+		netInt := result.Interfaces[interfaceName]
 		for _, netAddress := range netInt.Subnets {
 			size, _ := netAddress.IPNet.Mask.Size()
 			if netAddress.IPNet.IP.To4() != nil {

test/e2e/run_networking_test.go

@@ -2,15 +2,19 @@ package integration
 
 import (
 	"fmt"
+	"net"
 	"os"
 	"strings"
+	"syscall"
 
+	"github.com/containernetworking/plugins/pkg/ns"
 	. "github.com/containers/podman/v4/test/utils"
 	"github.com/containers/storage/pkg/stringid"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	. "github.com/onsi/gomega/gexec"
 	"github.com/uber/jaeger-client-go/utils"
+	"github.com/vishvananda/netlink"
 )
 
 var _ = Describe("Podman run networking", func() {
@@ -694,6 +698,157 @@ EXPOSE 2004-2005/tcp`, ALPINE)
 		Expect(session.OutputToString()).To(ContainSubstring("11.11.11.11"))
 	})
 
+	addAddr := func(cidr string, containerInterface netlink.Link) error {
+		_, ipnet, err := net.ParseCIDR(cidr)
+		Expect(err).To(BeNil())
+		addr := &netlink.Addr{IPNet: ipnet, Label: ""}
+		if err := netlink.AddrAdd(containerInterface, addr); err != nil && err != syscall.EEXIST {
+			return err
+		}
+		return nil
+	}
+
+	loopbackup := func() {
+		lo, err := netlink.LinkByName("lo")
+		Expect(err).To(BeNil())
+		err = netlink.LinkSetUp(lo)
+		Expect(err).To(BeNil())
+	}
+
+	linkup := func(name string, mac string, addresses []string) {
+		linkAttr := netlink.NewLinkAttrs()
+		linkAttr.Name = name
+		m, err := net.ParseMAC(mac)
+		Expect(err).To(BeNil())
+		linkAttr.HardwareAddr = net.HardwareAddr(m)
+		eth := &netlink.Dummy{LinkAttrs: linkAttr}
+		err = netlink.LinkAdd(eth)
+		Expect(err).To(BeNil())
+		err = netlink.LinkSetUp(eth)
+		Expect(err).To(BeNil())
+		for _, address := range addresses {
+			err := addAddr(address, eth)
+			Expect(err).To(BeNil())
+		}
+	}
+
+	routeAdd := func(gateway string) {
+		gw := net.ParseIP(gateway)
+		route := &netlink.Route{Dst: nil, Gw: gw}
+		netlink.RouteAdd(route)
+	}
+
+	setupNetworkNs := func(networkNSName string) {
+		ns.WithNetNSPath("/run/netns/"+networkNSName, func(_ ns.NetNS) error {
+			loopbackup()
+			linkup("eth0", "46:7f:45:6e:4f:c8", []string{"10.25.40.0/24", "fd04:3e42:4a4e:3381::/64"})
+			linkup("eth1", "56:6e:35:5d:3e:a8", []string{"10.88.0.0/16"})
+
+			routeAdd("10.25.40.0")
+			return nil
+		})
+	}
+
+	checkNetworkNsInspect := func(name string) {
+		inspectOut := podmanTest.InspectContainer(name)
+		Expect(inspectOut[0].NetworkSettings.IPAddress).To(Equal("10.25.40.0"))
+		Expect(inspectOut[0].NetworkSettings.IPPrefixLen).To(Equal(24))
+		Expect(len(inspectOut[0].NetworkSettings.SecondaryIPAddresses)).To(Equal(1))
+		Expect(inspectOut[0].NetworkSettings.SecondaryIPAddresses[0].Addr).To(Equal("10.88.0.0"))
+		Expect(inspectOut[0].NetworkSettings.SecondaryIPAddresses[0].PrefixLength).To(Equal(16))
+		Expect(inspectOut[0].NetworkSettings.GlobalIPv6Address).To(Equal("fd04:3e42:4a4e:3381::"))
+		Expect(inspectOut[0].NetworkSettings.GlobalIPv6PrefixLen).To(Equal(64))
+		Expect(len(inspectOut[0].NetworkSettings.SecondaryIPv6Addresses)).To(Equal(0))
+		Expect(inspectOut[0].NetworkSettings.MacAddress).To(Equal("46:7f:45:6e:4f:c8"))
+		Expect(len(inspectOut[0].NetworkSettings.AdditionalMacAddresses)).To(Equal(1))
+		Expect(inspectOut[0].NetworkSettings.AdditionalMacAddresses[0]).To(Equal("56:6e:35:5d:3e:a8"))
+		Expect(inspectOut[0].NetworkSettings.Gateway).To(Equal("10.25.40.0"))
+
+	}
+
+	It("podman run newtork inspect fails gracefully on non-reachable network ns", func() {
+		SkipIfRootless("ip netns is not supported for rootless users")
+
+		networkNSName := RandomString(12)
+		addNamedNetwork := SystemExec("ip", []string{"netns", "add", networkNSName})
+		Expect(addNamedNetwork).Should(Exit(0))
+
+		setupNetworkNs(networkNSName)
+
+		name := RandomString(12)
+		session := podmanTest.Podman([]string{"run", "-d", "--name", name, "--net", "ns:/run/netns/" + networkNSName, ALPINE, "top"})
+		session.WaitWithDefaultTimeout()
+
+		// delete the named network ns before inspect
+		delNetworkNamespace := SystemExec("ip", []string{"netns", "delete", networkNSName})
+		Expect(delNetworkNamespace).Should(Exit(0))
+
+		inspectOut := podmanTest.InspectContainer(name)
+		Expect(inspectOut[0].NetworkSettings.IPAddress).To(Equal(""))
+		Expect(len(inspectOut[0].NetworkSettings.Networks)).To(Equal(0))
+	})
+
+	It("podman inspect can handle joined network ns with multiple interfaces", func() {
+		SkipIfRootless("ip netns is not supported for rootless users")
+
+		networkNSName := RandomString(12)
+		addNamedNetwork := SystemExec("ip", []string{"netns", "add", networkNSName})
+		Expect(addNamedNetwork).Should(Exit(0))
+		defer func() {
+			delNetworkNamespace := SystemExec("ip", []string{"netns", "delete", networkNSName})
+			Expect(delNetworkNamespace).Should(Exit(0))
+		}()
+		setupNetworkNs(networkNSName)
+
+		name := RandomString(12)
+		session := podmanTest.Podman([]string{"run", "--name", name, "--net", "ns:/run/netns/" + networkNSName, ALPINE})
+		session.WaitWithDefaultTimeout()
+
+		session = podmanTest.Podman([]string{"container", "rm", name})
+		session.WaitWithDefaultTimeout()
+
+		// no network teardown should touch joined network ns interfaces
+		session = podmanTest.Podman([]string{"run", "-d", "--replace", "--name", name, "--net", "ns:/run/netns/" + networkNSName, ALPINE, "top"})
+		session.WaitWithDefaultTimeout()
+
+		checkNetworkNsInspect(name)
+	})
+
+	It("podman do not tamper with joined network ns interfaces", func() {
+		SkipIfRootless("ip netns is not supported for rootless users")
+
+		networkNSName := RandomString(12)
+		addNamedNetwork := SystemExec("ip", []string{"netns", "add", networkNSName})
+		Expect(addNamedNetwork).Should(Exit(0))
+		defer func() {
+			delNetworkNamespace := SystemExec("ip", []string{"netns", "delete", networkNSName})
+			Expect(delNetworkNamespace).Should(Exit(0))
+		}()
+
+		setupNetworkNs(networkNSName)
+
+		name := RandomString(12)
+		session := podmanTest.Podman([]string{"run", "--name", name, "--net", "ns:/run/netns/" + networkNSName, ALPINE})
+		session.WaitWithDefaultTimeout()
+
+		checkNetworkNsInspect(name)
+
+		name = RandomString(12)
+		session = podmanTest.Podman([]string{"run", "--name", name, "--net", "ns:/run/netns/" + networkNSName, ALPINE})
+		session.WaitWithDefaultTimeout()
+
+		checkNetworkNsInspect(name)
+
+		// delete container, the network inspect should not change
+		session = podmanTest.Podman([]string{"container", "rm", name})
+		session.WaitWithDefaultTimeout()
+
+		session = podmanTest.Podman([]string{"run", "-d", "--replace", "--name", name, "--net", "ns:/run/netns/" + networkNSName, ALPINE, "top"})
+		session.WaitWithDefaultTimeout()
+
+		checkNetworkNsInspect(name)
+	})
+
 	It("podman run network in bogus user created network namespace", func() {
 		session := podmanTest.Podman([]string{"run", "-dt", "--net", "ns:/run/netns/xxy", ALPINE, "wget", "www.podman.io"})
 		session.Wait(90)