Merge pull request #8287 from kinvolk/rata/userns-stateless-idmap

Add support for userns in stateless and stateful pods with idmap mounts (KEP-127, k8s >= 1.27)
2023-09-14 18:14:02 +08:00 · 2023-09-14 18:14:02 +08:00 · fe17f65159
commit fe17f65159
parent a831db9d35 83240a4f77
22 changed files with 1044 additions and 34 deletions
--- a/RELEASES.md
+++ b/RELEASES.md
@ -461,4 +461,4 @@ more quickly.
 | [NRI in CRI Support](https://github.com/containerd/containerd/pull/6019)               | containerd v1.7 | containerd v2.0          |
 | [gRPC Shim](https://github.com/containerd/containerd/pull/8052)                        | containerd v1.7 | containerd v2.0          |
 | [CRI Runtime Specific Snapshotter](https://github.com/containerd/containerd/pull/6899) | containerd v1.7 | containerd v2.0          |
-| [CRI Support for User Namespaces](https://github.com/containerd/containerd/pull/7679)  | containerd v1.7 | containerd v2.0          |
+| [CRI Support for User Namespaces](./docs/user-namespaces/README.md)                    | containerd v1.7 | containerd v2.0          |
--- a/docs/user-namespaces/README.md
+++ b/docs/user-namespaces/README.md
@ -0,0 +1,146 @@
+# Support for user namespaces
+
+Kubernetes supports running pods with user namespace since v1.25. This document explains the
+containerd support for this feature.
+
+## What are user namespaces?
+
+A user namespace isolates the user running inside the container from the one in the host.
+
+A process running as root in a container can run as a different (non-root) user in the host; in
+other words, the process has full privileges for operations inside the user namespace, but is
+unprivileged for operations outside the namespace.
+
+You can use this feature to reduce the damage a compromised container can do to the host or other
+pods in the same node. There are several security vulnerabilities rated either HIGH or CRITICAL that
+were not exploitable when user namespaces is active. It is expected user namespace will mitigate
+some future vulnerabilities too.
+
+See [the kubernetes documentation][kube-intro] for a high-level introduction to
+user namespaces.
+
+[kube-intro]: https://kubernetes.io/docs/concepts/workloads/pods/user-namespaces/#introduction
+
+## Stack requirements
+
+The Kubernetes implementation was redesigned in 1.27, so the requirements are different for versions
+pre and post Kubernetes 1.27.
+
+Please note that if you try to use user namespaces with containerd 1.6 or older, the `hostUsers:
+false` setting in your pod.spec will be **silently ignored**.
+
+### Kubernetes 1.25 and 1.26
+
+ * Containerd 1.7 or greater
+ * runc 1.1 or greater
+
+### Kubernetes 1.27 and greater
+
+ * Linux 6.3 or greater
+ * Containerd 2.0 or greater
+ * You can use runc or crun as the OCI runtime:
+   * runc 1.2 or greater
+   * crun 1.9 or greater
+
+Furthermore, all the file-systems used by the volumes in the pod need kernel-support for idmap
+mounts. Some popular file-systems that support idmap mounts in Linux 6.3 are: `btrfs`, `ext4`, `xfs`,
+`fat`, `tmpfs`, `overlayfs`.
+
+The kubelet is in charge of populating some files to the containers (like configmap, secrets, etc.).
+The file-system used in that path needs to support idmap mounts too. See [the Kubernetes
+documentation][kube-req] for more info on that.
+
+
+[kube-req]: https://kubernetes.io/docs/concepts/workloads/pods/user-namespaces/#before-you-begin
+
+## Creating a Kubernetes pod with user namespaces
+
+First check your containerd, Linux and Kubernetes versions. If those are okay, then there is no
+special configuration needed on conntainerd. You can just follow the steps in the [Kubernetes
+website][kube-example].
+
+[kube-example]: https://kubernetes.io/docs/tasks/configure-pod-container/user-namespaces/
+
+# Limitations
+
+You can check the limitations Kubernetes has [here][kube-limitations]. Note that different
+Kubernetes versions have different limitations, be sure to check the site for the Kubernetes version
+you are using.
+
+Different containerd versions have different limitations too, those are highlighted in this section.
+
+[kube-limitations]: https://kubernetes.io/docs/concepts/workloads/pods/user-namespaces/#limitations
+
+### containerd 1.7
+
+One limitation present in containerd 1.7 is that it needs to change the ownership of every file and
+directory inside the container image, during Pod startup. This means it has a storage overhead (the
+size of the container image is duplicated each time a pod is created) and can significantly impact
+the container startup latency.
+
+You can mitigate this limitation by switching `/sys/module/overlay/parameters/metacopy` to `Y`. This
+will significantly reduce the storage and performance overhead, as only the inode for each file of
+the container image will be duplicated, but not the content of the file. This means it will use less
+storage and it will be faster. However, it is not a panacea.
+
+If you change the metacopy param, make sure to do it in a way that is persistant across reboots. You
+should also be aware that this setting will be used for all containers, not just containers with
+user namespaces enabled. This will affect all the snapshots that you take manually (if you happen to
+do that). In that case, make sure to use the same value of `/sys/module/overlay/parameters/metacopy`
+when creating and restoring the snapshot.
+
+### containerd 2.0
+
+The storage and latency limitation from containerd 1.7 are not present in container 2.0 and above,
+if you use the overlay snapshotter (this is used by default). It will not use more storage at all,
+and there is no startup latency.
+
+This is achieved by using the kernel feature idmap mounts with the container rootfs (the container
+image). This allows an overlay file-system to expose the image with different UID/GID without copying
+the files nor the inodes, just using a bind-mount.
+
+You can check if you are using idmap mounts for the container image if you create a pod with user
+namespaces, exec into it and run:
+
+```
+mount | grep overlay
+```
+
+You should see a reference to the idmap mount in the `lowerdir` parameter, in this case we can see
+`idmapped` used there:
+
+```
+overlay on / type overlay (rw,relatime,lowerdir=/tmp/ovl-idmapped823885363/0,upperdir=/var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/1018/fs,workdir=/var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/1018/work)
+```
+
+## Creating a container with user namespaces with `ctr`
+
+You can also create a container with user namespaces using `ctr`. This is more low-level, be warned.
+
+Create an OCI bundle as explained [here][runc-bundle]. Then, change the UID/GID to 65536:
+
+```
+sudo chown -R 65536:65536 rootfs/
+```
+
+Copy [this config.json](./config.json) and replace `XXX-path-to-rootfs` with the
+absolute path to the rootfs you just chowned.
+
+Then create and start the container with:
+
+```
+sudo ctr create --config <path>/config.json userns-test
+sudo ctr t start userns-test
+```
+
+This will open a shell inside the container. You can run this, to verify you are inside a user
+namespace:
+
+```
+root@runc:/# cat /proc/self/uid_map
+         0      65536      65536
+```
+
+The output should be exactly the same.
+
+[runc-bundle]: https://github.com/opencontainers/runc#creating-an-oci-bundle
--- a/docs/user-namespaces/config.json
+++ b/docs/user-namespaces/config.json
@ -0,0 +1,199 @@
+{
+	"ociVersion": "1.0.2-dev",
+	"process": {
+		"terminal": true,
+		"user": {
+			"uid": 0,
+			"gid": 0
+		},
+		"args": [
+			"bash"
+		],
+		"env": [
+			"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
+			"TERM=xterm"
+		],
+		"cwd": "/",
+		"capabilities": {
+			"bounding": [
+				"CAP_AUDIT_WRITE",
+				"CAP_KILL",
+				"CAP_NET_BIND_SERVICE"
+			],
+			"effective": [
+				"CAP_AUDIT_WRITE",
+				"CAP_KILL",
+				"CAP_NET_BIND_SERVICE"
+			],
+			"inheritable": [
+				"CAP_AUDIT_WRITE",
+				"CAP_KILL",
+				"CAP_NET_BIND_SERVICE"
+			],
+			"permitted": [
+				"CAP_AUDIT_WRITE",
+				"CAP_KILL",
+				"CAP_NET_BIND_SERVICE"
+			],
+			"ambient": [
+				"CAP_AUDIT_WRITE",
+				"CAP_KILL",
+				"CAP_NET_BIND_SERVICE"
+			]
+		},
+		"rlimits": [
+			{
+				"type": "RLIMIT_NOFILE",
+				"hard": 1024,
+				"soft": 1024
+			}
+		],
+		"noNewPrivileges": true
+	},
+	"root": {
+		"path": "XXX-path-to-rootfs"
+	},
+	"hostname": "runc",
+	"mounts": [
+		{
+			"destination": "/proc",
+			"type": "proc",
+			"source": "proc"
+		},
+		{
+			"destination": "/dev",
+			"type": "tmpfs",
+			"source": "tmpfs",
+			"options": [
+				"nosuid",
+				"strictatime",
+				"mode=755",
+				"size=65536k"
+			]
+		},
+		{
+			"destination": "/dev/pts",
+			"type": "devpts",
+			"source": "devpts",
+			"options": [
+				"nosuid",
+				"noexec",
+				"newinstance",
+				"ptmxmode=0666",
+				"mode=0620",
+				"gid=5"
+			]
+		},
+		{
+			"destination": "/dev/shm",
+			"type": "tmpfs",
+			"source": "shm",
+			"options": [
+				"nosuid",
+				"noexec",
+				"nodev",
+				"mode=1777",
+				"size=65536k"
+			]
+		},
+		{
+			"destination": "/dev/mqueue",
+			"type": "mqueue",
+			"source": "mqueue",
+			"options": [
+				"nosuid",
+				"noexec",
+				"nodev"
+			]
+		},
+		{
+			"destination": "/sys",
+			"type": "sysfs",
+			"source": "sysfs",
+			"options": [
+				"nosuid",
+				"noexec",
+				"nodev",
+				"ro"
+			]
+		},
+		{
+			"destination": "/sys/fs/cgroup",
+			"type": "cgroup",
+			"source": "cgroup",
+			"options": [
+				"nosuid",
+				"noexec",
+				"nodev",
+				"relatime",
+				"ro"
+			]
+		}
+	],
+	"linux": {
+		    "uidMappings": [
+			      {
+			        "containerID": 0,
+			        "hostID": 65536,
+			        "size": 65536
+			      }
+			    ],
+			    "gidMappings": [
+			      {
+			        "containerID": 0,
+			        "hostID": 65536,
+			        "size": 65536
+			      }
+			    ],
+		"resources": {
+			"devices": [
+				{
+					"allow": false,
+					"access": "rwm"
+				}
+			]
+		},
+		"namespaces": [
+			{
+				"type": "pid"
+			},
+			{
+				"type": "network"
+			},
+			{
+				"type": "ipc"
+			},
+			{
+				"type": "uts"
+			},
+			{
+				"type": "mount"
+			},
+			{
+				"type": "cgroup"
+			},
+			{
+				"type": "user"
+			}
+		],
+		"maskedPaths": [
+			"/proc/acpi",
+			"/proc/asound",
+			"/proc/kcore",
+			"/proc/keys",
+			"/proc/latency_stats",
+			"/proc/timer_list",
+			"/proc/timer_stats",
+			"/proc/sched_debug",
+			"/sys/firmware",
+			"/proc/scsi"
+		],
+		"readonlyPaths": [
+			"/proc/bus",
+			"/proc/fs",
+			"/proc/irq",
+			"/proc/sys",
+			"/proc/sysrq-trigger"
+		]
+	}
+}
--- a/go.mod
+++ b/go.mod
@ -46,7 +46,7 @@ require (
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.1.0-rc4
 	github.com/opencontainers/runc v1.1.9
-	github.com/opencontainers/runtime-spec v1.1.0
+	github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4
 	github.com/opencontainers/runtime-tools v0.9.1-0.20221107090550-2e043c6bd626
 	github.com/opencontainers/selinux v1.11.0
 	github.com/pelletier/go-toml v1.9.5
--- a/go.sum
+++ b/go.sum
@ -800,8 +800,8 @@ github.com/opencontainers/runtime-spec v1.0.2/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/
 github.com/opencontainers/runtime-spec v1.0.3-0.20200929063507-e6143ca7d51d/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/opencontainers/runtime-spec v1.0.3-0.20210326190908-1c3f411f0417/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/opencontainers/runtime-spec v1.0.3-0.20220825212826-86290f6a00fb/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
-github.com/opencontainers/runtime-spec v1.1.0 h1:HHUyrt9mwHUjtasSbXSMvs4cyFxh+Bll4AjJ9odEGpg=
-github.com/opencontainers/runtime-spec v1.1.0/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
+github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4 h1:EctkgBjZ1y4q+sibyuuIgiKpa0QSd2elFtSSdNvBVow=
+github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/opencontainers/runtime-tools v0.0.0-20181011054405-1d69bd0f9c39/go.mod h1:r3f7wjNzSs2extwzU3Y+6pKfobzPh+kKFJ3ofN+3nfs=
 github.com/opencontainers/runtime-tools v0.9.1-0.20221107090550-2e043c6bd626 h1:DmNGcqH3WDbV5k8OJ+esPWbqUOX5rMLR2PMvziDMJi0=
 github.com/opencontainers/runtime-tools v0.9.1-0.20221107090550-2e043c6bd626/go.mod h1:BRHJJd0E+cx42OybVYSgUvZmU0B8P9gZuRXlZUP7TKI=
--- a/integration/client/go.mod
+++ b/integration/client/go.mod
@ -14,7 +14,7 @@ require (
 	github.com/containerd/typeurl/v2 v2.1.1
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.1.0-rc4
-	github.com/opencontainers/runtime-spec v1.1.0
+	github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4
 	github.com/stretchr/testify v1.8.4
 	go.opentelemetry.io/otel v1.14.0
 	go.opentelemetry.io/otel/sdk v1.14.0
--- a/integration/client/go.sum
+++ b/integration/client/go.sum
@ -1470,8 +1470,9 @@ github.com/opencontainers/runtime-spec v1.0.3-0.20200929063507-e6143ca7d51d/go.m
 github.com/opencontainers/runtime-spec v1.0.3-0.20210326190908-1c3f411f0417/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/opencontainers/runtime-spec v1.0.3-0.20220825212826-86290f6a00fb/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/opencontainers/runtime-spec v1.1.0-rc.2/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
-github.com/opencontainers/runtime-spec v1.1.0 h1:HHUyrt9mwHUjtasSbXSMvs4cyFxh+Bll4AjJ9odEGpg=
 github.com/opencontainers/runtime-spec v1.1.0/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
+github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4 h1:EctkgBjZ1y4q+sibyuuIgiKpa0QSd2elFtSSdNvBVow=
+github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/opencontainers/runtime-tools v0.0.0-20181011054405-1d69bd0f9c39/go.mod h1:r3f7wjNzSs2extwzU3Y+6pKfobzPh+kKFJ3ofN+3nfs=
 github.com/opencontainers/runtime-tools v0.9.0/go.mod h1:r3f7wjNzSs2extwzU3Y+6pKfobzPh+kKFJ3ofN+3nfs=
 github.com/opencontainers/runtime-tools v0.9.1-0.20221107090550-2e043c6bd626 h1:DmNGcqH3WDbV5k8OJ+esPWbqUOX5rMLR2PMvziDMJi0=
--- a/integration/main_test.go
+++ b/integration/main_test.go
@ -286,6 +286,10 @@ func WithWindowsResources(r *runtime.WindowsContainerResources) ContainerOpts {
 }

 func WithVolumeMount(hostPath, containerPath string) ContainerOpts {
+	return WithIDMapVolumeMount(hostPath, containerPath, nil, nil)
+}
+
+func WithIDMapVolumeMount(hostPath, containerPath string, uidMaps, gidMaps []*runtime.IDMapping) ContainerOpts {
 	return func(c *runtime.ContainerConfig) {
 		hostPath, _ = filepath.Abs(hostPath)
 		containerPath, _ = filepath.Abs(containerPath)
@ -293,6 +297,8 @@ func WithVolumeMount(hostPath, containerPath string) ContainerOpts {
 			HostPath:       hostPath,
 			ContainerPath:  containerPath,
 			SelinuxRelabel: selinux.GetEnabled(),
+			UidMappings:    uidMaps,
+			GidMappings:    gidMaps,
 		}
 		c.Mounts = append(c.Mounts, mount)
 	}
--- a/integration/pod_userns_linux_test.go
+++ b/integration/pod_userns_linux_test.go
@ -17,28 +17,137 @@
 package integration

 import (
+	"context"
+	"errors"
 	"fmt"
 	"os"
+	"os/user"
 	"path/filepath"
+	"strings"
 	"syscall"
 	"testing"
 	"time"

 	"github.com/containerd/containerd/integration/images"
+	runc "github.com/containerd/go-runc"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	exec "golang.org/x/sys/execabs"
+	"golang.org/x/sys/unix"
 	runtime "k8s.io/cri-api/pkg/apis/runtime/v1"
 )

+const (
+	defaultRoot = "/var/lib/containerd-test"
+)
+
+func supportsUserNS() bool {
+	if _, err := os.Stat("/proc/self/ns/user"); os.IsNotExist(err) {
+		return false
+	}
+	return true
+}
+
+func supportsIDMap(path string) bool {
+	treeFD, err := unix.OpenTree(-1, path, uint(unix.OPEN_TREE_CLONE|unix.OPEN_TREE_CLOEXEC))
+	if err != nil {
+		return false
+	}
+	defer unix.Close(treeFD)
+
+	// We want to test if idmap mounts are supported.
+	// So we use just some random mapping, it doesn't really matter which one.
+	// For the helper command, we just need something that is alive while we
+	// test this, a sleep 5 will do it.
+	cmd := exec.Command("sleep", "5")
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Cloneflags:  syscall.CLONE_NEWUSER,
+		UidMappings: []syscall.SysProcIDMap{{ContainerID: 0, HostID: 65536, Size: 65536}},
+		GidMappings: []syscall.SysProcIDMap{{ContainerID: 0, HostID: 65536, Size: 65536}},
+	}
+	if err := cmd.Start(); err != nil {
+		return false
+	}
+	defer func() {
+		_ = cmd.Process.Kill()
+		_ = cmd.Wait()
+	}()
+
+	usernsFD := fmt.Sprintf("/proc/%d/ns/user", cmd.Process.Pid)
+	var usernsFile *os.File
+	if usernsFile, err = os.Open(usernsFD); err != nil {
+		return false
+	}
+	defer usernsFile.Close()
+
+	attr := unix.MountAttr{
+		Attr_set:  unix.MOUNT_ATTR_IDMAP,
+		Userns_fd: uint64(usernsFile.Fd()),
+	}
+	if err := unix.MountSetattr(treeFD, "", unix.AT_EMPTY_PATH, &attr); err != nil {
+		return false
+	}
+
+	return true
+}
+
+// traversePath gives 755 permissions for all elements in tPath below
+// os.TempDir() and errors out if elements above it don't have read+exec
+// permissions for others.  tPath MUST be a descendant of os.TempDir(). The path
+// returned by testing.TempDir() usually is.
+func traversePath(tPath string) error {
+	// Check the assumption that the argument is under os.TempDir().
+	tempBase := os.TempDir()
+	if !strings.HasPrefix(tPath, tempBase) {
+		return fmt.Errorf("traversePath: %q is not a descendant of %q", tPath, tempBase)
+	}
+
+	var path string
+	for _, p := range strings.SplitAfter(tPath, "/") {
+		path = path + p
+		stats, err := os.Stat(path)
+		if err != nil {
+			return err
+		}
+
+		perm := stats.Mode().Perm()
+		if perm&0o5 == 0o5 {
+			continue
+		}
+		if strings.HasPrefix(tempBase, path) {
+			return fmt.Errorf("traversePath: directory %q MUST have read+exec permissions for others", path)
+		}
+
+		if err := os.Chmod(path, perm|0o755); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func TestPodUserNS(t *testing.T) {
 	containerID := uint32(0)
 	hostID := uint32(65536)
 	size := uint32(65536)
+	idmap := []*runtime.IDMapping{
+		{
+			ContainerId: containerID,
+			HostId:      hostID,
+			Length:      size,
+		},
+	}
+
+	volumeHostPath := t.TempDir()
+	if err := traversePath(volumeHostPath); err != nil {
+		t.Fatalf("failed to setup volume host path: %v", err)
+	}
+
 	for name, test := range map[string]struct {
 		sandboxOpts   []PodSandboxOpts
 		containerOpts []ContainerOpts
 		checkOutput   func(t *testing.T, output string)
+		hostVolumes   bool // whether to config uses host Volumes
 		expectErr     bool
 	}{
 		"userns uid mapping": {
@ -85,6 +194,31 @@ func TestPodUserNS(t *testing.T) {
 				assert.Contains(t, output, "=0=0=")
 			},
 		},
+		"volumes permissions": {
+			sandboxOpts: []PodSandboxOpts{
+				WithPodUserNs(containerID, hostID, size),
+			},
+			hostVolumes: true,
+			containerOpts: []ContainerOpts{
+				WithUserNamespace(containerID, hostID, size),
+				WithIDMapVolumeMount(volumeHostPath, "/mnt", idmap, idmap),
+				// Prints numeric UID and GID for path.
+				// For example, if UID and GID is 0 it will print: =0=0=
+				// We add the "=" signs so we use can assert.Contains() and be sure
+				// the UID/GID is 0 and not things like 100 (that contain 0).
+				// We can't use assert.Equal() easily as it contains timestamp, etc.
+				WithCommand("stat", "-c", "'=%u=%g='", "/mnt/"),
+			},
+			checkOutput: func(t *testing.T, output string) {
+				// The UID and GID should be the current user if chown/remap is done correctly.
+				uid := "0"
+				user, err := user.Current()
+				if user != nil && err == nil {
+					uid = user.Uid
+				}
+				assert.Contains(t, output, "="+uid+"="+uid+"=")
+			},
+		},
 		"fails with several mappings": {
 			sandboxOpts: []PodSandboxOpts{
 				WithPodUserNs(containerID, hostID, size),
@ -94,12 +228,17 @@ func TestPodUserNS(t *testing.T) {
 		},
 	} {
 		t.Run(name, func(t *testing.T) {
-			cmd := exec.Command("true")
-			cmd.SysProcAttr = &syscall.SysProcAttr{
-				Cloneflags: syscall.CLONE_NEWUSER,
+			if !supportsUserNS() {
+				t.Skip("User namespaces are not supported")
 			}
-			if err := cmd.Run(); err != nil {
-				t.Skip("skipping test: user namespaces are unavailable")
+			if !supportsIDMap(defaultRoot) {
+				t.Skipf("ID mappings are not supported on: %v", defaultRoot)
+			}
+			if test.hostVolumes && !supportsIDMap(volumeHostPath) {
+				t.Skipf("ID mappings are not supported host volume filesystem: %v", volumeHostPath)
+			}
+			if err := supportsRuncIDMap(); err != nil {
+				t.Skipf("OCI runtime doesn't support idmap mounts: %v", err)
 			}

 			testPodLogDir := t.TempDir()
@ -164,3 +303,22 @@ func TestPodUserNS(t *testing.T) {
 		})
 	}
 }
+
+func supportsRuncIDMap() error {
+	var r runc.Runc
+	features, err := r.Features(context.Background())
+	if err != nil {
+		// If the features command is not implemented, then runc is too old.
+		return fmt.Errorf("features command failed: %w", err)
+	}
+
+	if features.Linux.MountExtensions == nil || features.Linux.MountExtensions.IDMap == nil {
+		return errors.New("missing `mountExtensions.idmap` entry in `features` command")
+
+	}
+	if enabled := features.Linux.MountExtensions.IDMap.Enabled; enabled == nil || !*enabled {
+		return errors.New("idmap mounts not supported")
+	}
+
+	return nil
+}
--- a/pkg/cri/opts/spec_linux_opts.go
+++ b/pkg/cri/opts/spec_linux_opts.go
@ -162,8 +162,26 @@ func WithMounts(osi osinterface.OS, config *runtime.ContainerConfig, extra []*ru
 					return fmt.Errorf("relabel %q with %q failed: %w", src, mountLabel, err)
 				}
 			}
-			if mount.UidMappings != nil || mount.GidMappings != nil {
-				return fmt.Errorf("idmap mounts not yet supported, but they were requested for: %q", src)
+
+			var uidMapping []runtimespec.LinuxIDMapping
+			if mount.UidMappings != nil {
+				for _, mapping := range mount.UidMappings {
+					uidMapping = append(uidMapping, runtimespec.LinuxIDMapping{
+						HostID:      mapping.HostId,
+						ContainerID: mapping.ContainerId,
+						Size:        mapping.Length,
+					})
+				}
+			}
+			var gidMapping []runtimespec.LinuxIDMapping
+			if mount.GidMappings != nil {
+				for _, mapping := range mount.GidMappings {
+					gidMapping = append(gidMapping, runtimespec.LinuxIDMapping{
+						HostID:      mapping.HostId,
+						ContainerID: mapping.ContainerId,
+						Size:        mapping.Length,
+					})
+				}
 			}

 			s.Mounts = append(s.Mounts, runtimespec.Mount{
@ -171,6 +189,8 @@ func WithMounts(osi osinterface.OS, config *runtime.ContainerConfig, extra []*ru
 				Destination: dst,
 				Type:        "bind",
 				Options:     options,
+				UIDMappings: uidMapping,
+				GIDMappings: gidMapping,
 			})
 		}
 		return nil
--- a/pkg/cri/sbserver/container_create.go
+++ b/pkg/cri/sbserver/container_create.go
@ -157,7 +157,7 @@ func (c *criService) CreateContainer(ctx context.Context, r *runtime.CreateConta
 	var volumeMounts []*runtime.Mount
 	if !c.config.IgnoreImageDefinedVolumes {
 		// Create container image volumes mounts.
-		volumeMounts = c.volumeMounts(platform, containerRootDir, config.GetMounts(), &image.ImageSpec.Config)
+		volumeMounts = c.volumeMounts(platform, containerRootDir, config, &image.ImageSpec.Config)
 	} else if len(image.ImageSpec.Config.Volumes) != 0 {
 		log.G(ctx).Debugf("Ignoring volumes defined in image %v because IgnoreImageDefinedVolumes is set", image.ID)
 	}
@ -341,7 +341,17 @@ func (c *criService) CreateContainer(ctx context.Context, r *runtime.CreateConta
 // volumeMounts sets up image volumes for container. Rely on the removal of container
 // root directory to do cleanup. Note that image volume will be skipped, if there is criMounts
 // specified with the same destination.
-func (c *criService) volumeMounts(platform platforms.Platform, containerRootDir string, criMounts []*runtime.Mount, config *imagespec.ImageConfig) []*runtime.Mount {
+func (c *criService) volumeMounts(platform platforms.Platform, containerRootDir string, containerConfig *runtime.ContainerConfig, config *imagespec.ImageConfig) []*runtime.Mount {
+	var uidMappings, gidMappings []*runtime.IDMapping
+	if platform.OS == "linux" {
+		if usernsOpts := containerConfig.GetLinux().GetSecurityContext().GetNamespaceOptions().GetUsernsOptions(); usernsOpts != nil {
+			uidMappings = usernsOpts.GetUids()
+			gidMappings = usernsOpts.GetGids()
+		}
+	}
+
+	criMounts := containerConfig.GetMounts()
+
 	if len(config.Volumes) == 0 {
 		return nil
 	}
@ -371,6 +381,8 @@ func (c *criService) volumeMounts(platform platforms.Platform, containerRootDir
 			ContainerPath:  dst,
 			HostPath:       src,
 			SelinuxRelabel: true,
+			UidMappings:    uidMappings,
+			GidMappings:    gidMappings,
 		})
 	}
 	return mounts
@ -966,11 +978,17 @@ func (c *criService) buildDarwinSpec(
 	return specOpts, nil
 }

-// containerMounts sets up necessary container system file mounts
+// linuxContainerMounts sets up necessary container system file mounts
 // including /dev/shm, /etc/hosts and /etc/resolv.conf.
 func (c *criService) linuxContainerMounts(sandboxID string, config *runtime.ContainerConfig) []*runtime.Mount {
 	var mounts []*runtime.Mount
 	securityContext := config.GetLinux().GetSecurityContext()
+	var uidMappings, gidMappings []*runtime.IDMapping
+	if usernsOpts := securityContext.GetNamespaceOptions().GetUsernsOptions(); usernsOpts != nil {
+		uidMappings = usernsOpts.GetUids()
+		gidMappings = usernsOpts.GetGids()
+	}
+
 	if !isInCRIMounts(etcHostname, config.GetMounts()) {
 		// /etc/hostname is added since 1.1.6, 1.2.4 and 1.3.
 		// For in-place upgrade, the old sandbox doesn't have the hostname file,
@ -984,6 +1002,8 @@ func (c *criService) linuxContainerMounts(sandboxID string, config *runtime.Cont
 				HostPath:       hostpath,
 				Readonly:       securityContext.GetReadonlyRootfs(),
 				SelinuxRelabel: true,
+				UidMappings:    uidMappings,
+				GidMappings:    gidMappings,
 			})
 		}
 	}
@ -994,6 +1014,8 @@ func (c *criService) linuxContainerMounts(sandboxID string, config *runtime.Cont
 			HostPath:       c.getSandboxHosts(sandboxID),
 			Readonly:       securityContext.GetReadonlyRootfs(),
 			SelinuxRelabel: true,
+			UidMappings:    uidMappings,
+			GidMappings:    gidMappings,
 		})
 	}

@ -1005,6 +1027,8 @@ func (c *criService) linuxContainerMounts(sandboxID string, config *runtime.Cont
 			HostPath:       c.getResolvPath(sandboxID),
 			Readonly:       securityContext.GetReadonlyRootfs(),
 			SelinuxRelabel: true,
+			UidMappings:    uidMappings,
+			GidMappings:    gidMappings,
 		})
 	}

@ -1018,6 +1042,17 @@ func (c *criService) linuxContainerMounts(sandboxID string, config *runtime.Cont
 			HostPath:       sandboxDevShm,
 			Readonly:       false,
 			SelinuxRelabel: sandboxDevShm != devShm,
+			// XXX: tmpfs support for idmap mounts got merged in
+			// Linux 6.3.
+			// Our Ubuntu 22.04 CI runs with 5.15 kernels, so
+			// disabling idmap mounts for this case makes the CI
+			// happy (the other fs used support idmap mounts in 5.15
+			// kernels).
+			// We can enable this at a later stage, but as this
+			// tmpfs mount is exposed empty to the container (no
+			// prepopulated files) and using the hostIPC with userns
+			// is blocked by k8s, we can just avoid using the
+			// mappings and it should work fine.
 		})
 	}
 	return mounts
--- a/pkg/cri/sbserver/container_create_test.go
+++ b/pkg/cri/sbserver/container_create_test.go
@ -231,12 +231,22 @@ func TestContainerSpecCommand(t *testing.T) {

 func TestVolumeMounts(t *testing.T) {
 	testContainerRootDir := "test-container-root"
+	idmap := []*runtime.IDMapping{
+		{
+			ContainerId: 0,
+			HostId:      100,
+			Length:      1,
+		},
+	}
+
 	for _, test := range []struct {
 		desc              string
 		platform          platforms.Platform
 		criMounts         []*runtime.Mount
+		usernsEnabled     bool
 		imageVolumes      map[string]struct{}
 		expectedMountDest []string
+		expectedMappings  []*runtime.IDMapping
 	}{
 		{
 			desc: "should setup rw mount for image volumes",
@ -297,25 +307,88 @@ func TestVolumeMounts(t *testing.T) {
 				"/abs/test-volume-4",
 			},
 		},
+		{
+			desc:          "should include mappings for image volumes on Linux",
+			platform:      platforms.Platform{OS: "linux"},
+			usernsEnabled: true,
+			imageVolumes: map[string]struct{}{
+				"/test-volume-1/": {},
+				"/test-volume-2/": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-2/",
+				"/test-volume-2/",
+			},
+			expectedMappings: idmap,
+		},
+		{
+			desc:          "should NOT include mappings for image volumes on Linux if !userns",
+			platform:      platforms.Platform{OS: "linux"},
+			usernsEnabled: false,
+			imageVolumes: map[string]struct{}{
+				"/test-volume-1/": {},
+				"/test-volume-2/": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-2/",
+				"/test-volume-2/",
+			},
+		},
+		{
+			desc:          "should convert rel imageVolume paths to abs paths and add userns mappings",
+			platform:      platforms.Platform{OS: "linux"},
+			usernsEnabled: true,
+			imageVolumes: map[string]struct{}{
+				"test-volume-1/":       {},
+				"C:/test-volume-2/":    {},
+				"../../test-volume-3/": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-1",
+				"/C:/test-volume-2",
+				"/test-volume-3",
+			},
+			expectedMappings: idmap,
+		},
 	} {
 		test := test
 		t.Run(test.desc, func(t *testing.T) {
 			config := &imagespec.ImageConfig{
 				Volumes: test.imageVolumes,
 			}
+			containerConfig := &runtime.ContainerConfig{Mounts: test.criMounts}
+			if test.usernsEnabled {
+				containerConfig.Linux = &runtime.LinuxContainerConfig{
+					SecurityContext: &runtime.LinuxContainerSecurityContext{
+						NamespaceOptions: &runtime.NamespaceOption{
+							UsernsOptions: &runtime.UserNamespace{
+								Mode: runtime.NamespaceMode_POD,
+								Uids: idmap,
+								Gids: idmap,
+							},
+						},
+					},
+				}
+			}
+
 			c := newTestCRIService()
-			got := c.volumeMounts(test.platform, testContainerRootDir, test.criMounts, config)
+			got := c.volumeMounts(test.platform, testContainerRootDir, containerConfig, config)
 			assert.Len(t, got, len(test.expectedMountDest))
 			for _, dest := range test.expectedMountDest {
 				found := false
 				for _, m := range got {
-					if m.ContainerPath == dest {
+					if m.ContainerPath != dest {
+						continue
+					}
 					found = true
 					assert.Equal(t,
 						filepath.Dir(m.HostPath),
 						filepath.Join(testContainerRootDir, "volumes"))
-						break
+					if test.expectedMappings != nil {
+						assert.Equal(t, test.expectedMappings, m.UidMappings)
+						assert.Equal(t, test.expectedMappings, m.GidMappings)
 					}
+					break
 				}
 				assert.True(t, found)
 			}
@ -481,6 +554,14 @@ func TestBaseRuntimeSpec(t *testing.T) {

 func TestLinuxContainerMounts(t *testing.T) {
 	const testSandboxID = "test-id"
+	idmap := []*runtime.IDMapping{
+		{
+			ContainerId: 0,
+			HostId:      100,
+			Length:      1,
+		},
+	}
+
 	for _, test := range []struct {
 		desc            string
 		statFn          func(string) (os.FileInfo, error)
@ -550,6 +631,50 @@ func TestLinuxContainerMounts(t *testing.T) {
 				},
 			},
 		},
+		{
+			desc: "should setup uidMappings/gidMappings when userns is used",
+			securityContext: &runtime.LinuxContainerSecurityContext{
+				NamespaceOptions: &runtime.NamespaceOption{
+					UsernsOptions: &runtime.UserNamespace{
+						Mode: runtime.NamespaceMode_POD,
+						Uids: idmap,
+						Gids: idmap,
+					},
+				},
+			},
+			expectedMounts: []*runtime.Mount{
+				{
+					ContainerPath:  "/etc/hostname",
+					HostPath:       filepath.Join(testRootDir, sandboxesDir, testSandboxID, "hostname"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+					UidMappings:    idmap,
+					GidMappings:    idmap,
+				},
+				{
+					ContainerPath:  "/etc/hosts",
+					HostPath:       filepath.Join(testRootDir, sandboxesDir, testSandboxID, "hosts"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+					UidMappings:    idmap,
+					GidMappings:    idmap,
+				},
+				{
+					ContainerPath:  resolvConfPath,
+					HostPath:       filepath.Join(testRootDir, sandboxesDir, testSandboxID, "resolv.conf"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+					UidMappings:    idmap,
+					GidMappings:    idmap,
+				},
+				{
+					ContainerPath:  "/dev/shm",
+					HostPath:       filepath.Join(testStateDir, sandboxesDir, testSandboxID, "shm"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+				},
+			},
+		},
 		{
 			desc: "should use host /dev/shm when host ipc is set",
 			securityContext: &runtime.LinuxContainerSecurityContext{
--- a/pkg/cri/server/container_create.go
+++ b/pkg/cri/server/container_create.go
@ -143,7 +143,7 @@ func (c *criService) CreateContainer(ctx context.Context, r *runtime.CreateConta
 	var volumeMounts []*runtime.Mount
 	if !c.config.IgnoreImageDefinedVolumes {
 		// Create container image volumes mounts.
-		volumeMounts = c.volumeMounts(containerRootDir, config.GetMounts(), &image.ImageSpec.Config)
+		volumeMounts = c.volumeMounts(containerRootDir, config, &image.ImageSpec.Config)
 	} else if len(image.ImageSpec.Config.Volumes) != 0 {
 		log.G(ctx).Debugf("Ignoring volumes defined in image %v because IgnoreImageDefinedVolumes is set", image.ID)
 	}
@ -318,10 +318,19 @@ func (c *criService) CreateContainer(ctx context.Context, r *runtime.CreateConta
 // volumeMounts sets up image volumes for container. Rely on the removal of container
 // root directory to do cleanup. Note that image volume will be skipped, if there is criMounts
 // specified with the same destination.
-func (c *criService) volumeMounts(containerRootDir string, criMounts []*runtime.Mount, config *imagespec.ImageConfig) []*runtime.Mount {
+func (c *criService) volumeMounts(containerRootDir string, containerConfig *runtime.ContainerConfig, config *imagespec.ImageConfig) []*runtime.Mount {
 	if len(config.Volumes) == 0 {
 		return nil
 	}
+	var uidMappings, gidMappings []*runtime.IDMapping
+	if goruntime.GOOS != "windows" {
+		if usernsOpts := containerConfig.GetLinux().GetSecurityContext().GetNamespaceOptions().GetUsernsOptions(); usernsOpts != nil {
+			uidMappings = usernsOpts.GetUids()
+			gidMappings = usernsOpts.GetGids()
+		}
+	}
+
+	criMounts := containerConfig.GetMounts()
 	var mounts []*runtime.Mount
 	for dst := range config.Volumes {
 		if isInCRIMounts(dst, criMounts) {
@ -343,6 +352,8 @@ func (c *criService) volumeMounts(containerRootDir string, criMounts []*runtime.
 			ContainerPath:  dst,
 			HostPath:       src,
 			SelinuxRelabel: true,
+			UidMappings:    uidMappings,
+			GidMappings:    gidMappings,
 		})
 	}
 	return mounts
--- a/pkg/cri/server/container_create_linux.go
+++ b/pkg/cri/server/container_create_linux.go
@ -62,6 +62,12 @@ const (
 func (c *criService) containerMounts(sandboxID string, config *runtime.ContainerConfig) []*runtime.Mount {
 	var mounts []*runtime.Mount
 	securityContext := config.GetLinux().GetSecurityContext()
+	var uidMappings, gidMappings []*runtime.IDMapping
+	if usernsOpts := securityContext.GetNamespaceOptions().GetUsernsOptions(); usernsOpts != nil {
+		uidMappings = usernsOpts.GetUids()
+		gidMappings = usernsOpts.GetGids()
+	}
+
 	if !isInCRIMounts(etcHostname, config.GetMounts()) {
 		// /etc/hostname is added since 1.1.6, 1.2.4 and 1.3.
 		// For in-place upgrade, the old sandbox doesn't have the hostname file,
@ -75,6 +81,8 @@ func (c *criService) containerMounts(sandboxID string, config *runtime.Container
 				HostPath:       hostpath,
 				Readonly:       securityContext.GetReadonlyRootfs(),
 				SelinuxRelabel: true,
+				UidMappings:    uidMappings,
+				GidMappings:    gidMappings,
 			})
 		}
 	}
@ -85,6 +93,8 @@ func (c *criService) containerMounts(sandboxID string, config *runtime.Container
 			HostPath:       c.getSandboxHosts(sandboxID),
 			Readonly:       securityContext.GetReadonlyRootfs(),
 			SelinuxRelabel: true,
+			UidMappings:    uidMappings,
+			GidMappings:    gidMappings,
 		})
 	}

@ -96,6 +106,8 @@ func (c *criService) containerMounts(sandboxID string, config *runtime.Container
 			HostPath:       c.getResolvPath(sandboxID),
 			Readonly:       securityContext.GetReadonlyRootfs(),
 			SelinuxRelabel: true,
+			UidMappings:    uidMappings,
+			GidMappings:    gidMappings,
 		})
 	}

@ -109,6 +121,16 @@ func (c *criService) containerMounts(sandboxID string, config *runtime.Container
 			HostPath:       sandboxDevShm,
 			Readonly:       false,
 			SelinuxRelabel: sandboxDevShm != devShm,
+			// XXX: tmpfs support for idmap mounts got merged in
+			// Linux 6.3.
+			// Our CI runs with 5.15 kernels, so disabling idmap
+			// mounts for this case makes the CI happy (the other fs
+			// used support idmap mounts in 5.15 kernels).
+			// We can enable this at a later stage, but as this
+			// tmpfs mount is exposed empty to the container (no
+			// prepopulated files) and using the hostIPC with userns
+			// is blocked by k8s, we can just avoid using the
+			// mappings and it should work fine.
 		})
 	}
 	return mounts
--- a/pkg/cri/server/container_create_linux_test.go
+++ b/pkg/cri/server/container_create_linux_test.go
@ -459,6 +459,14 @@ func TestContainerAndSandboxPrivileged(t *testing.T) {

 func TestContainerMounts(t *testing.T) {
 	const testSandboxID = "test-id"
+	idmap := []*runtime.IDMapping{
+		{
+			ContainerId: 0,
+			HostId:      100,
+			Length:      1,
+		},
+	}
+
 	for _, test := range []struct {
 		desc            string
 		statFn          func(string) (os.FileInfo, error)
@ -528,6 +536,50 @@ func TestContainerMounts(t *testing.T) {
 				},
 			},
 		},
+		{
+			desc: "should setup uidMappings/gidMappings when userns is used",
+			securityContext: &runtime.LinuxContainerSecurityContext{
+				NamespaceOptions: &runtime.NamespaceOption{
+					UsernsOptions: &runtime.UserNamespace{
+						Mode: runtime.NamespaceMode_POD,
+						Uids: idmap,
+						Gids: idmap,
+					},
+				},
+			},
+			expectedMounts: []*runtime.Mount{
+				{
+					ContainerPath:  "/etc/hostname",
+					HostPath:       filepath.Join(testRootDir, sandboxesDir, testSandboxID, "hostname"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+					UidMappings:    idmap,
+					GidMappings:    idmap,
+				},
+				{
+					ContainerPath:  "/etc/hosts",
+					HostPath:       filepath.Join(testRootDir, sandboxesDir, testSandboxID, "hosts"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+					UidMappings:    idmap,
+					GidMappings:    idmap,
+				},
+				{
+					ContainerPath:  resolvConfPath,
+					HostPath:       filepath.Join(testRootDir, sandboxesDir, testSandboxID, "resolv.conf"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+					UidMappings:    idmap,
+					GidMappings:    idmap,
+				},
+				{
+					ContainerPath:  "/dev/shm",
+					HostPath:       filepath.Join(testStateDir, sandboxesDir, testSandboxID, "shm"),
+					Readonly:       false,
+					SelinuxRelabel: true,
+				},
+			},
+		},
 		{
 			desc: "should use host /dev/shm when host ipc is set",
 			securityContext: &runtime.LinuxContainerSecurityContext{
@ -2259,3 +2311,141 @@ containerEdits:
 		})
 	}
 }
+
+// TestLinuxVolumeMounts tests the linux-specific parts of VolumeMounts.
+func TestLinuxVolumeMounts(t *testing.T) {
+	testContainerRootDir := "test-container-root"
+	idmap := []*runtime.IDMapping{
+		{
+			ContainerId: 0,
+			HostId:      100,
+			Length:      1,
+		},
+	}
+
+	for _, test := range []struct {
+		desc              string
+		criMounts         []*runtime.Mount
+		imageVolumes      map[string]struct{}
+		usernsEnabled     bool
+		expectedMountDest []string
+		expectedMappings  []*runtime.IDMapping
+	}{
+		{
+			desc:          "should skip image volumes if already mounted by CRI",
+			usernsEnabled: true,
+			criMounts: []*runtime.Mount{
+				{
+					ContainerPath: "/test-volume-1",
+					HostPath:      "/test-hostpath-1",
+				},
+			},
+			imageVolumes: map[string]struct{}{
+				"/test-volume-1": {},
+				"/test-volume-2": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-2",
+			},
+			expectedMappings: idmap,
+		},
+		{
+			desc:          "should include mappings for image volumes",
+			usernsEnabled: true,
+			imageVolumes: map[string]struct{}{
+				"/test-volume-1/": {},
+				"/test-volume-2/": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-2/",
+				"/test-volume-2/",
+			},
+			expectedMappings: idmap,
+		},
+		{
+			desc: "should convert rel imageVolume paths to abs paths",
+			imageVolumes: map[string]struct{}{
+				"test-volume-1/":       {},
+				"./test-volume-2/":     {},
+				"../../test-volume-3/": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-1",
+				"/test-volume-2",
+				"/test-volume-3",
+			},
+		},
+		{
+			desc:          "should convert rel imageVolume paths to abs paths and add userns mappings",
+			usernsEnabled: true,
+			imageVolumes: map[string]struct{}{
+				"test-volume-1/":       {},
+				"./test-volume-2/":     {},
+				"../../test-volume-3/": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-1",
+				"/test-volume-2",
+				"/test-volume-3",
+			},
+			expectedMappings: idmap,
+		},
+		{
+			desc: "doesn't include mappings for image volumes if userns is disabled",
+			imageVolumes: map[string]struct{}{
+				"/test-volume-1/": {},
+				"/test-volume-2/": {},
+			},
+			expectedMountDest: []string{
+				"/test-volume-2/",
+				"/test-volume-2/",
+			},
+		},
+	} {
+		test := test
+		t.Run(test.desc, func(t *testing.T) {
+			config := &imagespec.ImageConfig{
+				Volumes: test.imageVolumes,
+			}
+			containerConfig := &runtime.ContainerConfig{
+				Mounts: test.criMounts,
+			}
+
+			if test.usernsEnabled {
+				containerConfig.Linux = &runtime.LinuxContainerConfig{
+					SecurityContext: &runtime.LinuxContainerSecurityContext{
+						NamespaceOptions: &runtime.NamespaceOption{
+							UsernsOptions: &runtime.UserNamespace{
+								Mode: runtime.NamespaceMode_POD,
+								Uids: idmap,
+								Gids: idmap,
+							},
+						},
+					},
+				}
+			}
+
+			c := newTestCRIService()
+			got := c.volumeMounts(testContainerRootDir, containerConfig, config)
+			assert.Len(t, got, len(test.expectedMountDest))
+			for _, dest := range test.expectedMountDest {
+				found := false
+				for _, m := range got {
+					if m.ContainerPath != dest {
+						continue
+					}
+					found = true
+					assert.Equal(t,
+						filepath.Dir(m.HostPath),
+						filepath.Join(testContainerRootDir, "volumes"))
+
+					if test.expectedMappings != nil {
+						assert.Equal(t, test.expectedMappings, m.UidMappings)
+						assert.Equal(t, test.expectedMappings, m.GidMappings)
+					}
+				}
+				assert.True(t, found)
+			}
+		})
+	}
+}
--- a/pkg/cri/server/container_create_test.go
+++ b/pkg/cri/server/container_create_test.go
@ -279,8 +279,9 @@ func TestVolumeMounts(t *testing.T) {
 			config := &imagespec.ImageConfig{
 				Volumes: test.imageVolumes,
 			}
+			containerConfig := &runtime.ContainerConfig{Mounts: test.criMounts}
 			c := newTestCRIService()
-			got := c.volumeMounts(testContainerRootDir, test.criMounts, config)
+			got := c.volumeMounts(testContainerRootDir, containerConfig, config)
 			assert.Len(t, got, len(test.expectedMountDest))
 			for _, dest := range test.expectedMountDest {
 				found := false
--- a/pkg/process/init.go
+++ b/pkg/process/init.go
@ -21,6 +21,7 @@ package process
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@ -140,6 +141,13 @@ func (p *Init) Create(ctx context.Context, r *CreateConfig) error {
 	if socket != nil {
 		opts.ConsoleSocket = socket
 	}
+
+	// runc ignores silently features it doesn't know about, so for things that this is
+	// problematic let's check if this runc version supports them.
+	if err := p.validateRuncFeatures(ctx, r.Bundle); err != nil {
+		return fmt.Errorf("failed to detect OCI runtime features: %w", err)
+	}
+
 	if err := p.runtime.Create(ctx, r.ID, r.Bundle, opts); err != nil {
 		return p.runtimeError(err, "OCI runtime create failed")
 	}
@ -173,6 +181,56 @@ func (p *Init) Create(ctx context.Context, r *CreateConfig) error {
 	return nil
 }

+func (p *Init) validateRuncFeatures(ctx context.Context, bundle string) error {
+	// TODO: We should remove the logic from here and rebase on #8509.
+	// This way we can avoid the call to readConfig() here and the call to p.runtime.Features()
+	// in validateIDMapMounts().
+	// But that PR is not yet merged nor it is clear if it will be refactored.
+	// Do this contained hack for now.
+	spec, err := readConfig(bundle)
+	if err != nil {
+		return fmt.Errorf("failed to read config: %w", err)
+	}
+
+	if err := p.validateIDMapMounts(ctx, spec); err != nil {
+		return fmt.Errorf("OCI runtime doesn't support idmap mounts: %w", err)
+	}
+
+	return nil
+}
+
+func (p *Init) validateIDMapMounts(ctx context.Context, spec *specs.Spec) error {
+	var used bool
+	for _, m := range spec.Mounts {
+		if m.UIDMappings != nil || m.GIDMappings != nil {
+			used = true
+			break
+		}
+	}
+
+	if !used {
+		return nil
+	}
+
+	// From here onwards, we require idmap mounts. So if we fail to check, we return an error.
+	features, err := p.runtime.Features(ctx)
+	if err != nil {
+		// If the features command is not implemented, then runc is too old.
+		return fmt.Errorf("features command failed: %w", err)
+
+	}
+
+	if features.Linux.MountExtensions == nil || features.Linux.MountExtensions.IDMap == nil {
+		return errors.New("missing `mountExtensions.idmap` entry in `features` command")
+	}
+
+	if enabled := features.Linux.MountExtensions.IDMap.Enabled; enabled == nil || !*enabled {
+		return errors.New("idmap mounts not supported")
+	}
+
+	return nil
+}
+
 func (p *Init) openStdin(path string) error {
 	sc, err := fifo.OpenFifo(context.Background(), path, unix.O_WRONLY|unix.O_NONBLOCK, 0)
 	if err != nil {
--- a/pkg/process/utils.go
+++ b/pkg/process/utils.go
@ -21,6 +21,7 @@ package process
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@ -31,6 +32,7 @@ import (

 	"github.com/containerd/containerd/errdefs"
 	runc "github.com/containerd/go-runc"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
 	"golang.org/x/sys/unix"
 )

@ -39,6 +41,8 @@ const (
 	RuncRoot = "/run/containerd/runc"
 	// InitPidFile name of the file that contains the init pid
 	InitPidFile = "init.pid"
+	// configFile is the name of the runc config file
+	configFile = "config.json"
 )

 // safePid is a thread safe wrapper for pid.
@ -184,3 +188,23 @@ func stateName(v interface{}) string {
 	}
 	panic(fmt.Errorf("invalid state %v", v))
 }
+
+func readConfig(path string) (spec *specs.Spec, err error) {
+	cfg := filepath.Join(path, configFile)
+	f, err := os.Open(cfg)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, fmt.Errorf("JSON specification file %s not found", cfg)
+		}
+		return nil, err
+	}
+	defer f.Close()
+
+	if err = json.NewDecoder(f).Decode(&spec); err != nil {
+		return nil, fmt.Errorf("failed to parse config: %w", err)
+	}
+	if spec == nil {
+		return nil, errors.New("config cannot be null")
+	}
+	return spec, nil
+}
--- a/script/setup/crun-version
+++ b/script/setup/crun-version
@ -1 +1 @@
-1.8.7
+1.9
--- a/vendor/github.com/opencontainers/runtime-spec/specs-go/features/features.go
+++ b/vendor/github.com/opencontainers/runtime-spec/specs-go/features/features.go
@ -41,6 +41,7 @@ type Linux struct {
 	Apparmor        *Apparmor        `json:"apparmor,omitempty"`
 	Selinux         *Selinux         `json:"selinux,omitempty"`
 	IntelRdt        *IntelRdt        `json:"intelRdt,omitempty"`
+	MountExtensions *MountExtensions `json:"mountExtensions,omitempty"`
 }

 // Cgroup represents the "cgroup" field.
@ -123,3 +124,16 @@ type IntelRdt struct {
 	// Nil value means "unknown", not "false".
 	Enabled *bool `json:"enabled,omitempty"`
 }
+
+// MountExtensions represents the "mountExtensions" field.
+type MountExtensions struct {
+	// IDMap represents the status of idmap mounts support.
+	IDMap *IDMap `json:"idmap,omitempty"`
+}
+
+type IDMap struct {
+	// Enabled represents whether idmap mounts supports is compiled in.
+	// Unrelated to whether the host supports it or not.
+	// Nil value means "unknown", not "false".
+	Enabled *bool `json:"enabled,omitempty"`
+}
--- a/vendor/github.com/opencontainers/runtime-spec/specs-go/version.go
+++ b/vendor/github.com/opencontainers/runtime-spec/specs-go/version.go
@ -11,7 +11,7 @@ const (
 	VersionPatch = 0

 	// VersionDev indicates development branch. Releases will be empty string.
-	VersionDev = ""
+	VersionDev = "+dev"
 )

 // Version is the specification version that the package types support.
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@ -343,7 +343,7 @@ github.com/opencontainers/image-spec/specs-go/v1
 # github.com/opencontainers/runc v1.1.9
 ## explicit; go 1.17
 github.com/opencontainers/runc/libcontainer/user
-# github.com/opencontainers/runtime-spec v1.1.0
+# github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4
 ## explicit
 github.com/opencontainers/runtime-spec/specs-go
 github.com/opencontainers/runtime-spec/specs-go/features
 @ -1 +1 @@
 .8.7
 .9