fix rootless port forwarding with network dis-/connect

The rootlessport forwarder requires a child IP to be set. This must be a
valid ip in the container network namespace. The problem is that after a
network disconnect and connect the eth0 ip changed. Therefore the
packages are dropped since the source ip does no longer exists in the
netns.
One solution is to set the child IP to 127.0.0.1, however this is a
security problem. [1]

To fix this we have to recreate the ports after network connect and
disconnect. To make this work the rootlessport process exposes a socket
where podman network connect/disconnect connect to and send to new child
IP to rootlessport. The rootlessport process will remove all ports and
recreate them with the new correct child IP.

Also bump rootlesskit to v0.14.3 to fix a race with RemovePort().

Fixes #10052

[1] https://nvd.nist.gov/vuln/detail/CVE-2021-20199

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

1 files changed, 33 insertions, 2 deletions

diff --git a/libpod/networking_linux.go b/libpod/networking_linux.go
index 0f3e03e06..8e9b5997c 100644
--- a/libpod/networking_linux.go
+++ b/libpod/networking_linux.go
@@ -1214,7 +1214,29 @@ func (c *Container) NetworkDisconnect(nameOrID, netName string, force bool) erro
 		}
 	}
 	c.state.NetworkStatus = tmpNetworkStatus
-	return c.save()
+	err = c.save()
+	if err != nil {
+		return err
+	}
+
+	// OCICNI will set the loopback adpter down on teardown so we should set it up again
+	err = c.state.NetNS.Do(func(_ ns.NetNS) error {
+		link, err := netlink.LinkByName("lo")
+		if err != nil {
+			return err
+		}
+		err = netlink.LinkSetUp(link)
+		return err
+	})
+	if err != nil {
+		logrus.Warnf("failed to set loopback adpter up in the container: %v", err)
+	}
+	// Reload ports when there are still connected networks, maybe we removed the network interface with the child ip.
+	// Reloading without connected networks does not make sense, so we can skip this step.
+	if rootless.IsRootless() && len(tmpNetworkStatus) > 0 {
+		return c.reloadRootlessRLKPortMapping()
+	}
+	return nil
 }
 
 // ConnectNetwork connects a container to a given network
@@ -1306,7 +1328,16 @@ func (c *Container) NetworkConnect(nameOrID, netName string, aliases []string) e
 		networkStatus[index] = networkResults[0]
 		c.state.NetworkStatus = networkStatus
 	}
-	return c.save()
+	err = c.save()
+	if err != nil {
+		return err
+	}
+	// The first network needs a port reload to set the correct child ip for the rootlessport process.
+	// Adding a second network does not require a port reload because the child ip is still valid.
+	if rootless.IsRootless() && len(networks) == 0 {
+		return c.reloadRootlessRLKPortMapping()
+	}
+	return nil
 }
 
 // DisconnectContainerFromNetwork removes a container from its CNI network