Is it possible to use volume copyup together with --userns auto and volume option idmap=uids=@2000-1000-1?

[eriksjolund]

In this example I populate a named volume in a Containerfile.
I want all the contents of the volume to have ownership 1000:1000 in the container
but ownership 2000:2000 on the host.

Do you know if this is possible? (I don't get it to work)

I installed Podman from the git main branch (git commit 290d94d )

1. Become root

   sudo -i
   

2. Create directory

   mkdir /root/ctr
   

3. Create file /root/ctr/Containerfile containing

   FROM docker.io/library/ubuntu
   RUN mkdir /vol \
     && echo hello > /vol/file.txt \
     && chown -R 1000:1000 /vol
   VOLUME /vol
   

4. Build container image

   podman build -t testimg /root/ctr/
   

5. Create volume

   podman volume create --opt o=uid=2000,gid=2000 vol1
   

6. Run container

    podman run \
     --rm \
     --userns auto \
     --user 1000:1000 \
     --mount 'type=volume,source=vol1,destination=/vol,Z=true,idmap=uids=@2000-1000-1;gids=@2000-1000-1' \
     localhost/testimg sh -c "ls -lnd /vol && ls -ln /vol"
   

   The following output is printed

   drwxr-xr-x. 2 1000 1000 22 Oct 21 18:51 /vol
   total 4
   -rw-r--r--. 1 65534 65534 6 Oct 21 18:51 file.txt
   

Describe the results you received

The following output is printed in Step 6

drwxr-xr-x. 2 1000 1000 22 Oct 21 18:51 /vol
total 4
-rw-r--r--. 1 65534 65534 6 Oct 21 18:51 file.txt

Describe the results you expected

I expected to see the following output being printed in Step 6

drwxr-xr-x. 2 1000 1000 22 Oct 21 18:51 /vol
total 4
-rw-r--r--. 1 1000 1000 6 Oct 21 18:51 file.txt

podman info output

Click me

host:
  arch: arm64
  buildahVersion: 1.38.0-dev
  cgroupControllers:
  - cpuset
  - cpu
  - io
  - memory
  - pids
  - rdma
  - misc
  cgroupManager: cgroupfs
  cgroupVersion: v2
  conmon:
    package: conmon-2.1.12-2.fc41.aarch64
    path: /usr/bin/conmon
    version: 'conmon version 2.1.12, commit: '
  cpuUtilization:
    idlePercent: 99.74
    systemPercent: 0.15
    userPercent: 0.11
  cpus: 2
  databaseBackend: sqlite
  distribution:
    distribution: fedora
    variant: coreos
    version: "42"
  eventLogger: file
  freeLocks: 2023
  hostname: localhost.localdomain
  idMappings:
    gidmap: null
    uidmap: null
  kernel: 6.11.0-0.rc5.20240829gitd5d547aa7b51.46.fc42.aarch64
  linkmode: dynamic
  logDriver: journald
  memFree: 3308859392
  memTotal: 4081860608
  networkBackend: netavark
  networkBackendInfo:
    backend: netavark
    dns:
      package: aardvark-dns-1.12.1-1.fc41.aarch64
      path: /usr/libexec/podman/aardvark-dns
      version: aardvark-dns 1.12.1
    package: netavark-1.12.2-1.fc42.aarch64
    path: /usr/libexec/podman/netavark
    version: netavark 1.12.2
  ociRuntime:
    name: crun
    package: crun-1.15-2.fc41.aarch64
    path: /usr/bin/crun
    version: |-
      crun version 1.15
      commit: e6eacaf4034e84185fd8780ac9262bbf57082278
      rundir: /run/crun
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +LIBKRUN +WASM:wasmedge +YAJL
  os: linux
  pasta:
    executable: /usr/bin/pasta
    package: passt-0^20240821.g1d6142f-1.fc42.aarch64
    version: |
      pasta 0^20240821.g1d6142f-1.fc42.aarch64-pasta
      Copyright Red Hat
      GNU General Public License, version 2 or later
        <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
      This is free software: you are free to change and redistribute it.
      There is NO WARRANTY, to the extent permitted by law.
  remoteSocket:
    exists: true
    path: /run/podman/podman.sock
  rootlessNetworkCmd: pasta
  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: false
    seccompEnabled: true
    seccompProfilePath: /usr/share/containers/seccomp.json
    selinuxEnabled: true
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns-1.2.2-3.fc41.aarch64
    version: |-
      slirp4netns version 1.2.2
      commit: 0ee2d87523e906518d34a6b423271e4826f71faf
      libslirp: 4.8.0
      SLIRP_CONFIG_VERSION_MAX: 5
      libseccomp: 2.5.5
  swapFree: 0
  swapTotal: 0
  uptime: 7h 41m 0.00s (Approximately 0.29 days)
  variant: v8
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  network:
  - bridge
  - macvlan
  - ipvlan
  volume:
  - local
registries:
  search:
  - registry.fedoraproject.org
  - registry.access.redhat.com
  - docker.io
store:
  configFile: /usr/share/containers/storage.conf
  containerStore:
    number: 0
    paused: 0
    running: 0
    stopped: 0
  graphDriverName: overlay
  graphOptions:
    overlay.imagestore: /usr/lib/containers/storage
    overlay.mountopt: nodev,metacopy=on
    overlay.use_composefs: "false"
  graphRoot: /var/lib/containers/storage
  graphRootAllocated: 26238496768
  graphRootUsed: 10148061184
  graphStatus:
    Backing Filesystem: xfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Supports shifting: "true"
    Supports volatile: "true"
    Using metacopy: "true"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 13
  runRoot: /run/containers/storage
  transientStore: false
  volumePath: /var/lib/containers/storage/volumes
version:
  APIVersion: 5.3.0-dev
  Built: 1729021641
  BuiltTime: Tue Oct 15 19:47:21 2024
  GitCommit: 290d94d3c00857dd582ffbee6bd0677a0904c783
  GoVersion: go1.22.6
  Os: linux
  OsArch: linux/arm64
  Version: 5.3.0-dev

[eriksjolund]

Probably this is an analogous problem (but somewhat simpler as it does not make use of a Containerfile)
I tried the following with podman 5.3.0-RC1

1. sudo -i
2. Create file /root/test.bash containing

   #!/bin/bash
   set -o errexit
   podman volume rm --force vol1 > /dev/null
   podman volume create --opt o=uid=2,gid=2 vol1 > /dev/null
   podman run \
     --rm \
     --userns=auto \
     --mount "type=volume,source=vol1,destination=/etc/cron.daily,Z=true,idmap=uids=@2-0-10000;gids=@2-0-10000" \
     docker.io/library/ubuntu \
     "$@"
   

3. Run command

    bash test.bash ls -ld /etc/cron.daily
   

   The following output is printed

   drwxr-xr-x. 2 root root 36 Oct 26 08:43 /etc/cron.daily
   

4. Run command

    bash test.bash ls -l /etc/cron.daily
   

   The following output is printed

   total 8
   -rwxr-xr-x. 1 nobody nogroup 1478 Mar 22  2024 apt-compat
   -rwxr-xr-x. 1 nobody nogroup  123 Feb  5  2024 dpkg
   

The ownership root:root shown in Step 3 match how it looks like in docker.io/library/ubuntu

# podman run --rm docker.io/library/ubuntu ls -ld /etc/cron.daily
drwxr-xr-x. 2 root root 36 Oct 11 02:14 /etc/cron.daily

The ownership nobody:nogroup shown in Step 4 does not match how it looks like in docker.io/library/ubuntu

# podman run --rm docker.io/library/ubuntu ls -l /etc/cron.daily
total 8
-rwxr-xr-x. 1 root root 1478 Mar 22  2024 apt-compat
-rwxr-xr-x. 1 root root  123 Feb  5  2024 dpkg
# 

In Step 4 I had hoped to see the ownerhip root:root

side note:

I also tried a slightly modified bash script:

--- test.bash.orig	2024-10-26 08:55:47.298401621 +0000
+++ test.bash	2024-10-26 08:55:54.863212796 +0000
@@ -3,10 +3,10 @@
 set -o errexit
 
 podman volume rm --force vol1 > /dev/null
-podman volume create --opt o=uid=2,gid=2 vol1 > /dev/null
+podman volume create vol1 > /dev/null
 podman run \
   --rm \
   --userns=auto \
-  --mount "type=volume,source=vol1,destination=/etc/cron.daily,Z=true,idmap=uids=@2-0-10000;gids=@2-0-10000" \
+  --mount "type=volume,source=vol1,destination=/etc/cron.daily,Z=true,idmap=uids=@0-0-10000;gids=@0-0-10000" \
   docker.io/library/ubuntu \
   "$@"

but it produced the same ownership results.