An error occurred while joining the pod with userns=keep-id

[xfoobar]

Issue Description

An error occurred while joining the pod with userns=keep-id

OS: openSUSE Tumbleweed 20230513
podman version: 4.5.0

Steps to reproduce the issue

Steps to reproduce the issue
1.

export PODMAN_USERNS=keep-id
podman pod create --name=test-pod

podman run -it --rm --pod=test-pod --name=test-container fedora:38 echo foobar

podman pod rm -f test-pod

Describe the results you received

46504c362dab5c22265af12a53f397f5252e3e34fa39469f62c70375b79bc627
Error: runc: runc create failed: unable to start container process: error during container init: error mounting "sysfs" to rootfs at "/sys": mount sysfs:/sys (via /proc/self/fd/12), flags: 0xf: operation not permitted: OCI permission denied
46504c362dab5c22265af12a53f397f5252e3e34fa39469f62c70375b79bc627

Describe the results you expected

46504c362dab5c22265af12a53f397f5252e3e34fa39469f62c70375b79bc627
foobar
46504c362dab5c22265af12a53f397f5252e3e34fa39469f62c70375b79bc627

podman info output

host:
  arch: amd64
  buildahVersion: 1.30.0
  cgroupControllers:
  - cpu
  - memory
  - pids
  cgroupManager: systemd
  cgroupVersion: v2
  conmon:
    package: conmon-2.1.7-1.2.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.1.7, commit: unknown'
  cpuUtilization:
    idlePercent: 99.94
    systemPercent: 0.04
    userPercent: 0.02
  cpus: 10
  databaseBackend: boltdb
  distribution:
    distribution: '"opensuse-tumbleweed"'
    version: "20230513"
  eventLogger: journald
  hostname: main
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
  kernel: 6.3.1-2-default
  linkmode: dynamic
  logDriver: journald
  memFree: 100806656
  memTotal: 1025937408
  networkBackend: cni
  ociRuntime:
    name: runc
    package: runc-1.1.7-1.1.x86_64
    path: /usr/bin/runc
    version: |-
      runc version 1.1.7
      commit: v1.1.7-0-g860f061b76bb
      spec: 1.0.2-dev
      go: go1.19.8
      libseccomp: 2.5.4
  os: linux
  remoteSocket:
    path: /run/user/1000/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /etc/containers/seccomp.json
    selinuxEnabled: false
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns-1.2.0-1.2.x86_64
    version: |-
      slirp4netns version 1.2.0
      commit: unknown
      libslirp: 4.7.0
      SLIRP_CONFIG_VERSION_MAX: 5
      libseccomp: 2.5.4
  swapFree: 0
  swapTotal: 0
  uptime: 23h 3m 55.00s (Approximately 0.96 days)
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  - journald
  network:
  - bridge
  - macvlan
  - ipvlan
  volume:
  - local
registries:
  search:
  - registry.opensuse.org
  - registry.suse.com
  - docker.io
store:
  configFile: /home/foobar/.config/containers/storage.conf
  containerStore:
    number: 0
    paused: 0
    running: 0
    stopped: 0
  graphDriverName: btrfs
  graphOptions: {}
  graphRoot: /home/foobar/.local/share/containers/storage
  graphRootAllocated: 215284166656
  graphRootUsed: 72409272320
  graphStatus:
    Build Version: Btrfs v6.1.3
    Library Version: "102"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 30
  runRoot: /run/user/1000/containers
  transientStore: false
  volumePath: /home/foobar/.local/share/containers/storage/volumes
version:
  APIVersion: 4.5.0
  Built: 1681776000
  BuiltTime: Tue Apr 18 08:00:00 2023
  GitCommit: ""
  GoVersion: go1.19.8
  Os: linux
  OsArch: linux/amd64
  Version: 4.5.0

Podman in a container

No

Privileged Or Rootless

Rootless

Upstream Latest Release

Yes

Additional environment details

SELinux disabled

Additional information

No additional configuration files

[giuseppe]

does it work if you use crun?

[giuseppe]

do you unset the environment variable after you create the POD? Otherwise it will end up creating a new user namespace for the container

[xfoobar]

do you unset the environment variable after you create the POD? Otherwise it will end up creating a new user namespace for the container

Actually I tested it in a shell script.

export PODMAN_USERNS=keep-id
podman pod create --name=test-pod
podman run -it --rm --pod=test-pod --name=test-container fedora:38 echo foobar
podman pod rm -f test-pod

[xfoobar]

does it work if you use crun?

Thanks, the problem was solved after I installed crun

[giuseppe]

I think the error is in your script. You need to unset the environment variable after you create the pod or even better just use --userns keep-id. Otherwise you end up with two different namespaces.

[xfoobar]

I think the error is in your script. You need to unset the environment variable after you create the pod or even better just use --userns keep-id. Otherwise you end up with two different namespaces.

Yeah, it also worked, but you cannot set --pod and --userns at the same time when creating a container(output: Error: --userns and --pod cannot be set together), so any userns related environment variable should be ignored when using the --pod

[giuseppe]

that should not be allowed. I've opened a PR to block it: #18601