containerd · crosbymichael · Nov 18, 2021 · Oct 28, 2021
diff --git a/docs/cri/config.md b/docs/cri/config.md
@@ -107,6 +107,19 @@ version = 2
     # set to nil or `unconfined`, and the default used when the runtime default seccomp profile is requested.
   unset_seccomp_profile = ""
 
+  # enable_unprivileged_ports configures net.ipv4.ip_unprivileged_port_start=0
+  # for all containers which are not using host network
+  # and if it is not overwritten by PodSandboxConfig
+  # Note that currently default is set to disabled but target change it in future, see:
+  #   [k8s discussion](https://github.com/kubernetes/kubernetes/issues/102612)
+  enable_unprivileged_ports = false
+
+  # enable_unprivileged_icmp configures net.ipv4.ping_group_range="0 2147483647"
+  # for all containers which are not using host network, are not running in user namespace
+  # and if it is not overwritten by PodSandboxConfig
+  # Note that currently default is set to disabled but target change it in future together with enable_unprivileged_ports
+  enable_unprivileged_icmp = false
+
   # 'plugins."io.containerd.grpc.v1.cri".containerd' contains config related to containerd
   [plugins."io.containerd.grpc.v1.cri".containerd]
 

diff --git a/pkg/cri/config/config.go b/pkg/cri/config/config.go
@@ -282,6 +282,17 @@ type PluginConfig struct {
 	// of being placed under the hardcoded directory /var/run/netns. Changing this setting requires
 	// that all containers are deleted.
 	NetNSMountsUnderStateDir bool `toml:"netns_mounts_under_state_dir" json:"netnsMountsUnderStateDir"`
+	// EnableUnprivilegedPorts configures net.ipv4.ip_unprivileged_port_start=0
+	// for all containers which are not using host network
+	// and if it is not overwritten by PodSandboxConfig
+	// Note that currently default is set to disabled but target change it in future, see:
+	//   https://github.com/kubernetes/kubernetes/issues/102612
+	EnableUnprivilegedPorts bool `toml:"enable_unprivileged_ports" json:"enableUnprivilegedPorts"`
+	// EnableUnprivilegedICMP configures net.ipv4.ping_group_range="0 2147483647"
+	// for all containers which are not using host network, are not running in user namespace
+	// and if it is not overwritten by PodSandboxConfig
+	// Note that currently default is set to disabled but target change it in future together with EnableUnprivilegedPorts
+	EnableUnprivilegedICMP bool `toml:"enable_unprivileged_icmp" json:"enableUnprivilegedICMP"`
 }
 
 // X509KeyPairStreaming contains the x509 configuration for streaming

diff --git a/pkg/cri/server/sandbox_run_linux.go b/pkg/cri/server/sandbox_run_linux.go
@@ -34,6 +34,7 @@ import (
 	"github.com/containerd/containerd/pkg/cri/annotations"
 	customopts "github.com/containerd/containerd/pkg/cri/opts"
 	osinterface "github.com/containerd/containerd/pkg/os"
+	"github.com/containerd/containerd/pkg/userns"
 )
 
 func (c *criService) sandboxContainerSpec(id string, config *runtime.PodSandboxConfig,
@@ -134,6 +135,19 @@ func (c *criService) sandboxContainerSpec(id string, config *runtime.PodSandboxC
 
 	// Add sysctls
 	sysctls := config.GetLinux().GetSysctls()
+	if sysctls == nil {
+		sysctls = make(map[string]string)
+	}
+	_, ipUnprivilegedPortStart := sysctls["net.ipv4.ip_unprivileged_port_start"]
+	_, pingGroupRange := sysctls["net.ipv4.ping_group_range"]
+	if nsOptions.GetNetwork() != runtime.NamespaceMode_NODE {
+		if c.config.EnableUnprivilegedPorts && !ipUnprivilegedPortStart {
+			sysctls["net.ipv4.ip_unprivileged_port_start"] = "0"
+		}
+		if c.config.EnableUnprivilegedICMP && !pingGroupRange && !userns.RunningInUserNS() {
+			sysctls["net.ipv4.ping_group_range"] = "0 2147483647"
+		}
+	}
 	specOpts = append(specOpts, customopts.WithSysctls(sysctls))
 
 	// Note: LinuxSandboxSecurityContext does not currently provide an apparmor profile

diff --git a/pkg/cri/server/sandbox_run_linux_test.go b/pkg/cri/server/sandbox_run_linux_test.go
@@ -115,6 +115,8 @@ func TestLinuxSandboxContainerSpec(t *testing.T) {
 				assert.Contains(t, spec.Linux.Namespaces, runtimespec.LinuxNamespace{
 					Type: runtimespec.IPCNamespace,
 				})
+				assert.Contains(t, spec.Linux.Sysctl["net.ipv4.ip_unprivileged_port_start"], "0")
+				assert.Contains(t, spec.Linux.Sysctl["net.ipv4.ping_group_range"], "0 2147483647")
 			},
 		},
 		"host namespace": {
@@ -142,6 +144,8 @@ func TestLinuxSandboxContainerSpec(t *testing.T) {
 				assert.NotContains(t, spec.Linux.Namespaces, runtimespec.LinuxNamespace{
 					Type: runtimespec.IPCNamespace,
 				})
+				assert.NotContains(t, spec.Linux.Sysctl["net.ipv4.ip_unprivileged_port_start"], "0")
+				assert.NotContains(t, spec.Linux.Sysctl["net.ipv4.ping_group_range"], "0 2147483647")
 			},
 		},
 		"should set supplemental groups correctly": {
@@ -156,9 +160,24 @@ func TestLinuxSandboxContainerSpec(t *testing.T) {
 				assert.Contains(t, spec.Process.User.AdditionalGids, uint32(2222))
 			},
 		},
+		"should overwrite default sysctls": {
+			configChange: func(c *runtime.PodSandboxConfig) {
+				c.Linux.Sysctls = map[string]string{
+					"net.ipv4.ip_unprivileged_port_start": "500",
+					"net.ipv4.ping_group_range":           "1 1000",
+				}
+			},
+			specCheck: func(t *testing.T, spec *runtimespec.Spec) {
+				require.NotNil(t, spec.Process)
+				assert.Contains(t, spec.Linux.Sysctl["net.ipv4.ip_unprivileged_port_start"], "500")
+				assert.Contains(t, spec.Linux.Sysctl["net.ipv4.ping_group_range"], "1 1000")
+			},
+		},
 	} {
 		t.Logf("TestCase %q", desc)
 		c := newTestCRIService()
+		c.config.EnableUnprivilegedICMP = true
+		c.config.EnableUnprivilegedPorts = true
 		config, imageConfig, specCheck := getRunPodSandboxTestData()
 		if test.configChange != nil {
 			test.configChange(config)