14 files changed, 376 insertions, 13 deletions

diff --git a/cmd/podman/networks/reload.go b/cmd/podman/networks/reload.go
new file mode 100644
index 000000000..16655c18c
--- /dev/null
+++ b/cmd/podman/networks/reload.go
@@ -0,0 +1,69 @@
+package network
+
+import (
+	"fmt"
+
+	"github.com/containers/podman/v2/cmd/podman/common"
+	"github.com/containers/podman/v2/cmd/podman/registry"
+	"github.com/containers/podman/v2/cmd/podman/utils"
+	"github.com/containers/podman/v2/cmd/podman/validate"
+	"github.com/containers/podman/v2/pkg/domain/entities"
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+)
+
+var (
+	networkReloadDescription = `reload container networks, recreating firewall rules`
+	networkReloadCommand     = &cobra.Command{
+		Use:   "reload [options] [CONTAINER...]",
+		Short: "Reload firewall rules for one or more containers",
+		Long:  networkReloadDescription,
+		RunE:  networkReload,
+		Args: func(cmd *cobra.Command, args []string) error {
+			return validate.CheckAllLatestAndCIDFile(cmd, args, false, false)
+		},
+		ValidArgsFunction: common.AutocompleteContainers,
+		Example: `podman network reload --latest
+  podman network reload 3c13ef6dd843
+  podman network reload test1 test2`,
+		Annotations: map[string]string{
+			registry.ParentNSRequired: "",
+		},
+	}
+)
+
+var (
+	reloadOptions entities.NetworkReloadOptions
+)
+
+func reloadFlags(flags *pflag.FlagSet) {
+	flags.BoolVarP(&reloadOptions.All, "all", "a", false, "Reload network configuration of all containers")
+}
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode},
+		Command: networkReloadCommand,
+		Parent:  networkCmd,
+	})
+	reloadFlags(networkReloadCommand.Flags())
+	validate.AddLatestFlag(networkReloadCommand, &reloadOptions.Latest)
+}
+
+func networkReload(cmd *cobra.Command, args []string) error {
+	responses, err := registry.ContainerEngine().NetworkReload(registry.Context(), args, reloadOptions)
+	if err != nil {
+		return err
+	}
+
+	var errs utils.OutputErrors
+	for _, r := range responses {
+		if r.Err == nil {
+			fmt.Println(r.Id)
+		} else {
+			errs = append(errs, r.Err)
+		}
+	}
+
+	return errs.PrintErrors()
+}
diff --git a/docs/source/markdown/podman-network-reload.1.md b/docs/source/markdown/podman-network-reload.1.md
new file mode 100644
index 000000000..dd8047297
--- /dev/null
+++ b/docs/source/markdown/podman-network-reload.1.md
@@ -0,0 +1,62 @@
+% podman-network-reload(1)
+
+## NAME
+podman\-network\-reload - Reload network configuration for containers
+
+## SYNOPSIS
+**podman network reload** [*options*] [*container...*]
+
+## DESCRIPTION
+Reload one or more container network configurations.
+
+Rootful Podman relies on iptables rules in order to provide network connectivity. If the iptables rules are deleted,
+this happens for example with `firewall-cmd --reload`, the container loses network connectivity. This command restores
+the network connectivity.
+
+This command is not available for rootless users since rootless containers are not affected by such connectivity problems.
+
+## OPTIONS
+#### **--all**, **-a**
+
+Reload network configuration of all containers.
+
+#### **--latest**, **-l**
+
+Instead of providing the container name or ID, use the last created container. If you use methods other than Podman
+to run containers such as CRI-O, the last started container could be from either of those methods.
+
+The latest option is not supported on the remote client.
+
+## EXAMPLE
+
+Reload the network configuration after a firewall reload.
+
+```
+# podman run -p 80:80 -d nginx
+b1b538e8bc4078fc3ee1c95b666ebc7449b9a97bacd15bcbe464a29e1be59c1c
+# curl 127.0.0.1
+works
+# sudo firewall-cmd --reload
+success
+# curl 127.0.0.1
+hangs
+# podman network reload b1b538e8bc40
+b1b538e8bc4078fc3ee1c95b666ebc7449b9a97bacd15bcbe464a29e1be59c1c
+# curl 127.0.0.1
+works
+```
+
+Reload the network configuration for all containers.
+
+```
+# podman network reload --all
+b1b538e8bc4078fc3ee1c95b666ebc7449b9a97bacd15bcbe464a29e1be59c1c
+fe7e8eca56f844ec33af10f0aa3b31b44a172776e3277b9550a623ed5d96e72b
+```
+
+
+## SEE ALSO
+podman(1), podman-network(1)
+
+## HISTORY
+December 2020, Originally compiled by Paul Holzinger <paul.holzinger@web.de>
diff --git a/docs/source/markdown/podman-network.1.md b/docs/source/markdown/podman-network.1.md
index d21b200d9..d11f0d7b6 100644
--- a/docs/source/markdown/podman-network.1.md
+++ b/docs/source/markdown/podman-network.1.md
@@ -11,14 +11,15 @@ The network command manages CNI networks for Podman. It is not supported for roo
 
 ## COMMANDS
 
-| Command  | Man Page                                            | Description                                                                  |
-| -------  | --------------------------------------------------- | ---------------------------------------------------------------------------- |
-| connect | [podman-network-connect(1)](podman-network-connect.1.md)| Connect a container to a network|
-| create | [podman-network-create(1)](podman-network-create.1.md)| Create a Podman CNI network|
-| disconnect | [podman-network-disconnect(1)](podman-network-disconnect.1.md)| Disconnect a container from a network|
-| inspect | [podman-network-inspect(1)](podman-network-inspect.1.md)| Displays the raw CNI network configuration for one or more networks|
-| ls | [podman-network-ls(1)](podman-network-ls.1.md)| Display a summary of CNI networks                        |
-| rm | [podman-network-rm(1)](podman-network-rm.1.md)| Remove one or more CNI networks                        |
+| Command    | Man Page                                                       | Description                                                         |
+| ---------- | -------------------------------------------------------------- | ------------------------------------------------------------------- |
+| connect    | [podman-network-connect(1)](podman-network-connect.1.md)       | Connect a container to a network                                    |
+| create     | [podman-network-create(1)](podman-network-create.1.md)         | Create a Podman CNI network                                         |
+| disconnect | [podman-network-disconnect(1)](podman-network-disconnect.1.md) | Disconnect a container from a network                               |
+| inspect    | [podman-network-inspect(1)](podman-network-inspect.1.md)       | Displays the raw CNI network configuration for one or more networks |
+| ls         | [podman-network-ls(1)](podman-network-ls.1.md)                 | Display a summary of CNI networks                                   |
+| reload     | [podman-network-reload(1)](podman-network-reload.1.md)         | Reload network configuration for containers                         |
+| rm         | [podman-network-rm(1)](podman-network-rm.1.md)                 | Remove one or more CNI networks                                     |
 
 ## SEE ALSO
 podman(1)
diff --git a/docs/source/network.rst b/docs/source/network.rst
index 0414c0880..2ecb97858 100644
--- a/docs/source/network.rst
+++ b/docs/source/network.rst
@@ -11,4 +11,6 @@ Network
 
 :doc:`ls <markdown/podman-network-ls.1>` network list
 
+:doc:`reload <markdown/podman-network-reload.1>` network reload
+
 :doc:`rm <markdown/podman-network-rm.1>` network rm
diff --git a/libpod/container_api.go b/libpod/container_api.go
index 6a7ddc421..1b33f16b4 100644
--- a/libpod/container_api.go
+++ b/libpod/container_api.go
@@ -639,6 +639,32 @@ func (c *Container) Sync() error {
 	return nil
 }
 
+// ReloadNetwork reconfigures the container's network.
+// Technically speaking, it will tear down and then reconfigure the container's
+// network namespace, which will result in all firewall rules being recreated.
+// It is mostly intended to be used in cases where the system firewall has been
+// reloaded, and existing rules have been wiped out. It is expected that some
+// downtime will result, as the rules are destroyed as part of this process.
+// At present, this only works on root containers; it may be expanded to restart
+// slirp4netns in the future to work with rootless containers as well.
+// Requires that the container must be running or created.
+func (c *Container) ReloadNetwork() error {
+	if !c.batched {
+		c.lock.Lock()
+		defer c.lock.Unlock()
+
+		if err := c.syncContainer(); err != nil {
+			return err
+		}
+	}
+
+	if !c.ensureState(define.ContainerStateCreated, define.ContainerStateRunning) {
+		return errors.Wrapf(define.ErrCtrStateInvalid, "cannot reload network unless container network has been configured")
+	}
+
+	return c.reloadNetwork()
+}
+
 // Refresh is DEPRECATED and REMOVED.
 func (c *Container) Refresh(ctx context.Context) error {
 	// This has been deprecated for a long while, and is in the process of
diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index 56575c195..a9a789ad8 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -230,6 +230,19 @@ func (c *Container) cleanupNetwork() error {
 	return nil
 }
 
+// reloadNetwork reloads the network for the given container, recreating
+// firewall rules.
+func (c *Container) reloadNetwork() error {
+	result, err := c.runtime.reloadContainerNetwork(c)
+	if err != nil {
+		return err
+	}
+
+	c.state.NetworkStatus = result
+
+	return c.save()
+}
+
 func (c *Container) getUserOverrides() *lookup.Overrides {
 	var hasPasswdFile, hasGroupFile bool
 	overrides := lookup.Overrides{}
diff --git a/libpod/container_internal_unsupported.go b/libpod/container_internal_unsupported.go
index c22e9a4a4..7f6fc9ec9 100644
--- a/libpod/container_internal_unsupported.go
+++ b/libpod/container_internal_unsupported.go
@@ -50,6 +50,10 @@ func (c *Container) cleanupOverlayMounts() error {
 	return nil
 }
 
+func (c *Container) reloadNetwork() error {
+	return define.ErrNotImplemented
+}
+
 func (c *Container) getUserOverrides() *lookup.Overrides {
 	return nil
 }
diff --git a/libpod/networking_linux.go b/libpod/networking_linux.go
index 15e470c80..c7db95eb3 100644
--- a/libpod/networking_linux.go
+++ b/libpod/networking_linux.go
@@ -13,6 +13,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"sort"
 	"strings"
 	"syscall"
@@ -740,8 +741,9 @@ func (r *Runtime) closeNetNS(ctr *Container) error {
 	return nil
 }
 
-// Tear down a network namespace, undoing all state associated with it.
-func (r *Runtime) teardownNetNS(ctr *Container) error {
+// Tear down a container's CNI network configuration, but do not tear down the
+// namespace itself.
+func (r *Runtime) teardownCNI(ctr *Container) error {
 	if ctr.state.NetNS == nil {
 		// The container has no network namespace, we're set
 		return nil
@@ -780,6 +782,19 @@ func (r *Runtime) teardownNetNS(ctr *Container) error {
 			return errors.Wrapf(err, "error tearing down CNI namespace configuration for container %s", ctr.ID())
 		}
 	}
+	return nil
+}
+
+// Tear down a network namespace, undoing all state associated with it.
+func (r *Runtime) teardownNetNS(ctr *Container) error {
+	if err := r.teardownCNI(ctr); err != nil {
+		return err
+	}
+
+	networks, _, err := ctr.networks()
+	if err != nil {
+		return err
+	}
 
 	// CNI-in-slirp4netns
 	if rootless.IsRootless() && len(networks) != 0 {
@@ -820,6 +835,68 @@ func getContainerNetNS(ctr *Container) (string, error) {
 	return "", nil
 }
 
+// Reload only works with containers with a configured network.
+// It will tear down, and then reconfigure, the network of the container.
+// This is mainly used when a reload of firewall rules wipes out existing
+// firewall configuration.
+// Efforts will be made to preserve MAC and IP addresses, but this only works if
+// the container only joined a single CNI network, and was only assigned a
+// single MAC or IP.
+// Only works on root containers at present, though in the future we could
+// extend this to stop + restart slirp4netns
+func (r *Runtime) reloadContainerNetwork(ctr *Container) ([]*cnitypes.Result, error) {
+	if ctr.state.NetNS == nil {
+		return nil, errors.Wrapf(define.ErrCtrStateInvalid, "container %s network is not configured, refusing to reload", ctr.ID())
+	}
+	if rootless.IsRootless() || ctr.config.NetMode.IsSlirp4netns() {
+		return nil, errors.Wrapf(define.ErrRootless, "network reload only supported for root containers")
+	}
+
+	logrus.Infof("Going to reload container %s network", ctr.ID())
+
+	var requestedIP net.IP
+	var requestedMAC net.HardwareAddr
+	// Set requested IP and MAC address, if possible.
+	if len(ctr.state.NetworkStatus) == 1 {
+		result := ctr.state.NetworkStatus[0]
+		if len(result.IPs) == 1 {
+			resIP := result.IPs[0]
+
+			requestedIP = resIP.Address.IP
+			ctr.requestedIP = requestedIP
+			logrus.Debugf("Going to preserve container %s IP address %s", ctr.ID(), ctr.requestedIP.String())
+
+			if resIP.Interface != nil && *resIP.Interface < len(result.Interfaces) && *resIP.Interface >= 0 {
+				var err error
+				requestedMAC, err = net.ParseMAC(result.Interfaces[*resIP.Interface].Mac)
+				if err != nil {
+					return nil, errors.Wrapf(err, "error parsing container %s MAC address %s", ctr.ID(), result.Interfaces[*resIP.Interface].Mac)
+				}
+				ctr.requestedMAC = requestedMAC
+				logrus.Debugf("Going to preserve container %s MAC address %s", ctr.ID(), ctr.requestedMAC.String())
+			}
+		}
+	}
+
+	err := r.teardownCNI(ctr)
+	if err != nil {
+		// teardownCNI will error if the iptables rules do not exists and this is the case after
+		// a firewall reload. The purpose of network reload is to recreate the rules if they do
+		// not exists so we should not log this specific error as error. This would confuse users otherwise.
+		b, rerr := regexp.MatchString("Couldn't load target `CNI-[a-f0-9]{24}':No such file or directory", err.Error())
+		if rerr == nil && !b {
+			logrus.Error(err)
+		} else {
+			logrus.Info(err)
+		}
+	}
+
+	// teardownCNI will clean the requested IP and MAC so we need to set them again
+	ctr.requestedIP = requestedIP
+	ctr.requestedMAC = requestedMAC
+	return r.configureNetNS(ctr, ctr.state.NetNS)
+}
+
 func getContainerNetIO(ctr *Container) (*netlink.LinkStatistics, error) {
 	var netStats *netlink.LinkStatistics
 	// rootless v2 cannot seem to resolve its network connection to
@@ -983,12 +1060,12 @@ func resultToBasicNetworkConfig(result *cnitypes.Result) (define.InspectBasicNet
 			config.IPAddress = ctrIP.Address.IP.String()
 			config.IPPrefixLen = size
 			config.Gateway = ctrIP.Gateway.String()
-			if ctrIP.Interface != nil && *ctrIP.Interface < len(result.Interfaces) && *ctrIP.Interface > 0 {
+			if ctrIP.Interface != nil && *ctrIP.Interface < len(result.Interfaces) && *ctrIP.Interface >= 0 {
 				config.MacAddress = result.Interfaces[*ctrIP.Interface].Mac
 			}
 		case ctrIP.Version == "4" && config.IPAddress != "":
 			config.SecondaryIPAddresses = append(config.SecondaryIPAddresses, ctrIP.Address.String())
-			if ctrIP.Interface != nil && *ctrIP.Interface < len(result.Interfaces) && *ctrIP.Interface > 0 {
+			if ctrIP.Interface != nil && *ctrIP.Interface < len(result.Interfaces) && *ctrIP.Interface >= 0 {
 				config.AdditionalMacAddresses = append(config.AdditionalMacAddresses, result.Interfaces[*ctrIP.Interface].Mac)
 			}
 		case ctrIP.Version == "6" && config.IPAddress == "":
diff --git a/libpod/networking_unsupported.go b/libpod/networking_unsupported.go
index 76bb01424..9e5c4adde 100644
--- a/libpod/networking_unsupported.go
+++ b/libpod/networking_unsupported.go
@@ -2,7 +2,10 @@
 
 package libpod
 
-import "github.com/containers/podman/v2/libpod/define"
+import (
+	cnitypes "github.com/containernetworking/cni/pkg/types/current"
+	"github.com/containers/podman/v2/libpod/define"
+)
 
 func (r *Runtime) setupRootlessNetNS(ctr *Container) error {
 	return define.ErrNotImplemented
@@ -28,6 +31,10 @@ func (c *Container) getContainerNetworkInfo() (*define.InspectNetworkSettings, e
 	return nil, define.ErrNotImplemented
 }
 
+func (r *Runtime) reloadContainerNetwork(ctr *Container) ([]*cnitypes.Result, error) {
+	return nil, define.ErrNotImplemented
+}
+
 func getCNINetworksDir() (string, error) {
 	return "", define.ErrNotImplemented
 }
diff --git a/pkg/domain/entities/engine_container.go b/pkg/domain/entities/engine_container.go
index df7da616a..a4f6c08e9 100644
--- a/pkg/domain/entities/engine_container.go
+++ b/pkg/domain/entities/engine_container.go
@@ -55,6 +55,7 @@ type ContainerEngine interface {
 	NetworkDisconnect(ctx context.Context, networkname string, options NetworkDisconnectOptions) error
 	NetworkInspect(ctx context.Context, namesOrIds []string, options InspectOptions) ([]NetworkInspectReport, []error, error)
 	NetworkList(ctx context.Context, options NetworkListOptions) ([]*NetworkListReport, error)
+	NetworkReload(ctx context.Context, names []string, options NetworkReloadOptions) ([]*NetworkReloadReport, error)
 	NetworkRm(ctx context.Context, namesOrIds []string, options NetworkRmOptions) ([]*NetworkRmReport, error)
 	PlayKube(ctx context.Context, path string, opts PlayKubeOptions) (*PlayKubeReport, error)
 	PodCreate(ctx context.Context, opts PodCreateOptions) (*PodCreateReport, error)
diff --git a/pkg/domain/entities/network.go b/pkg/domain/entities/network.go
index 65a110fd9..b76bfcac7 100644
--- a/pkg/domain/entities/network.go
+++ b/pkg/domain/entities/network.go
@@ -22,6 +22,19 @@ type NetworkListReport struct {
 // NetworkInspectReport describes the results from inspect networks
 type NetworkInspectReport map[string]interface{}
 
+// NetworkReloadOptions describes options for reloading container network
+// configuration.
+type NetworkReloadOptions struct {
+	All    bool
+	Latest bool
+}
+
+// NetworkReloadReport describes the results of reloading a container network.
+type NetworkReloadReport struct {
+	Id  string
+	Err error
+}
+
 // NetworkRmOptions describes options for removing networks
 type NetworkRmOptions struct {
 	Force bool
diff --git a/pkg/domain/infra/abi/network.go b/pkg/domain/infra/abi/network.go
index 6a219edd5..e5ecf5c72 100644
--- a/pkg/domain/infra/abi/network.go
+++ b/pkg/domain/infra/abi/network.go
@@ -60,6 +60,26 @@ func (ic *ContainerEngine) NetworkInspect(ctx context.Context, namesOrIds []stri
 	return rawCNINetworks, errs, nil
 }
 
+func (ic *ContainerEngine) NetworkReload(ctx context.Context, names []string, options entities.NetworkReloadOptions) ([]*entities.NetworkReloadReport, error) {
+	ctrs, err := getContainersByContext(options.All, options.Latest, names, ic.Libpod)
+	if err != nil {
+		return nil, err
+	}
+
+	reports := make([]*entities.NetworkReloadReport, 0, len(ctrs))
+	for _, ctr := range ctrs {
+		report := new(entities.NetworkReloadReport)
+		report.Id = ctr.ID()
+		report.Err = ctr.ReloadNetwork()
+		if options.All && errors.Cause(report.Err) == define.ErrCtrStateInvalid {
+			continue
+		}
+		reports = append(reports, report)
+	}
+
+	return reports, nil
+}
+
 func (ic *ContainerEngine) NetworkRm(ctx context.Context, namesOrIds []string, options entities.NetworkRmOptions) ([]*entities.NetworkRmReport, error) {
 	reports := []*entities.NetworkRmReport{}
 
diff --git a/pkg/domain/infra/tunnel/network.go b/pkg/domain/infra/tunnel/network.go
index 10ae03045..4845980f6 100644
--- a/pkg/domain/infra/tunnel/network.go
+++ b/pkg/domain/infra/tunnel/network.go
@@ -35,6 +35,10 @@ func (ic *ContainerEngine) NetworkInspect(ctx context.Context, namesOrIds []stri
 	return reports, errs, nil
 }
 
+func (ic *ContainerEngine) NetworkReload(ctx context.Context, names []string, options entities.NetworkReloadOptions) ([]*entities.NetworkReloadReport, error) {
+	return nil, errors.New("not implemented")
+}
+
 func (ic *ContainerEngine) NetworkRm(ctx context.Context, namesOrIds []string, options entities.NetworkRmOptions) ([]*entities.NetworkRmReport, error) {
 	reports := make([]*entities.NetworkRmReport, 0, len(namesOrIds))
 	for _, name := range namesOrIds {
diff --git a/test/system/500-networking.bats b/test/system/500-networking.bats
index 44cc731cf..a824ebcd7 100644
--- a/test/system/500-networking.bats
+++ b/test/system/500-networking.bats
@@ -116,4 +116,68 @@ load helpers
     fi
 }
 
+@test "podman network reload" {
+    skip_if_remote "podman network reload does not have remote support"
+    skip_if_rootless "podman network reload does not work rootless"
+
+    random_1=$(random_string 30)
+    HOST_PORT=12345
+    SERVER=http://127.0.0.1:$HOST_PORT
+
+    # Create a test file with random content
+    INDEX1=$PODMAN_TMPDIR/hello.txt
+    echo $random_1 > $INDEX1
+
+    # Bind-mount this file with a different name to a container running httpd
+    run_podman run -d --name myweb -p "$HOST_PORT:80" \
+               -v $INDEX1:/var/www/index.txt \
+               -w /var/www \
+               $IMAGE /bin/busybox-extras httpd -f -p 80
+    cid=$output
+
+    run_podman inspect $cid --format "{{.NetworkSettings.IPAddress}}"
+    ip="$output"
+    run_podman inspect $cid --format "{{.NetworkSettings.MacAddress}}"
+    mac="$output"
+
+    # Verify http contents: curl from localhost
+    run curl -s $SERVER/index.txt
+    is "$output" "$random_1" "curl 127.0.0.1:/index.txt"
+
+    # flush the CNI iptables here
+    run iptables -t nat -F CNI-HOSTPORT-DNAT
+
+    # check that we cannot curl (timeout after 5 sec)
+    run timeout 5 curl -s $SERVER/index.txt
+    if [ "$status" -ne 124 ]; then
+        die "curl did not timeout, status code: $status"
+    fi
+
+    # reload the network to recreate the iptables rules
+    run_podman network reload $cid
+    is "$output" "$cid" "Output does not match container ID"
+
+    # check that we still have the same mac and ip
+    run_podman inspect $cid --format "{{.NetworkSettings.IPAddress}}"
+    is "$output" "$ip" "IP address changed after podman network reload"
+    run_podman inspect $cid --format "{{.NetworkSettings.MacAddress}}"
+    is "$output" "$mac" "MAC address changed after podman network reload"
+
+    # check that we can still curl
+    run curl -s $SERVER/index.txt
+    is "$output" "$random_1" "curl 127.0.0.1:/index.txt"
+
+    # make sure --all is working and that this
+    # cmd also works if the iptables still exists
+    run_podman network reload --all
+    is "$output" "$cid" "Output does not match container ID"
+
+    # check that we can still curl
+    run curl -s $SERVER/index.txt
+    is "$output" "$random_1" "curl 127.0.0.1:/index.txt"
+
+    # cleanup the container
+    run_podman rm -f $cid
+}
+
 # vim: filetype=sh