Calling CopyToContainer through the podman socket does not preserve UID/GID information

[dwaynebradley]

Issue Description

When using the Docker SDK to call the CopyToContainer API through the podman.sock, Podman is not preserving the UID and GID of the folders and files in the TAR archive even when passing the CopyUIDGID: true option. Every folder and file are being copied into the container as root:root.

Steps to reproduce the issue

Steps to reproduce the issue

1. Clone test code - https://github.com/dwaynebradley/docker-copytocontainer-example.git
   • The sample code calls CopyToContainer API and passes the CopyUIDGID: true in the CopyToContainerOptions
2. View contents of the tar file to see permissions that have been set on the example folder and file - tar -tvf test-configs.tar
   • configs will be owned by 1001:1001
   • configs/test-config-file.txt will be owned by 1002:1002
3. Start Podman systemd service - systemctl --user enable --now podman.service
4. export DOCKER_HOST=unix://${XDG_RUNTIME_DIR}/podman/podman.sock
5. Run the test code to create the container that copies the contents of test-configs.tar into the container - go run main.go

Describe the results you received

1. Exec into the container that was created by the sample code - podman exec -ti copy-uidgid-test /bin/sh
2. Check ownership on the contents copied into the container
   • stat /configs - it will be owned by root:root
   • stat /configs/test-config-file.txt - if will also be owned by root:root

Describe the results you expected

I expected both the folder and file to have the same ownership as what is stored in the test-configs.tar file.

If I run this exact same code using Docker instead, the ownership on both the file and folder are retained inside of the container correctly.

podman info output

host:
  arch: amd64
  buildahVersion: 1.41.5
  cgroupControllers:
  - cpuset
  - cpu
  - io
  - memory
  - pids
  cgroupManager: systemd
  cgroupVersion: v2
  conmon:
    package: conmon-1:2.1.13-1
    path: /usr/bin/conmon
    version: 'conmon version 2.1.13, commit: 82de887596ed8ee6d9b2ee85e4f167f307bb569b'
  cpuUtilization:
    idlePercent: 99.07
    systemPercent: 0.46
    userPercent: 0.47
  cpus: 16
  databaseBackend: sqlite
  distribution:
    distribution: arch
    version: unknown
  emulatedArchitectures:
  - linux/arm
  - linux/arm64
  - linux/loong64
  - linux/mips64
  - linux/ppc
  - linux/ppc64
  - linux/ppc64le
  - linux/riscv32
  - linux/riscv64
  - linux/s390x
  eventLogger: journald
  freeLocks: 2039
  hostname: USRA1WHP6192208
  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: 6.6.87.2-microsoft-standard-WSL2
  linkmode: dynamic
  logDriver: journald
  memFree: 14528659456
  memTotal: 25199562752
  networkBackend: netavark
  networkBackendInfo:
    backend: netavark
    dns:
      package: aardvark-dns-1.16.0-1
      path: /usr/lib/podman/aardvark-dns
      version: aardvark-dns 1.16.0
    package: netavark-1.16.1-1
    path: /usr/lib/podman/netavark
    version: netavark 1.16.1
  ociRuntime:
    name: crun
    package: crun-1.24-1
    path: /usr/bin/crun
    version: |-
      crun version 1.24
      commit: 54693209039e5e04cbe3c8b1cd5fe2301219f0a1
      rundir: /run/user/1000/crun
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +YAJL
  os: linux
  pasta:
    executable: /usr/sbin/pasta
    package: passt-2025_09_19.623dbf6-1
    version: |
      pasta 2025_09_19.623dbf6
      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/user/1000/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_SET
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /etc/containers/seccomp.json
    selinuxEnabled: false
  serviceIsRemote: false
  slirp4netns:
    executable: ""
    package: ""
    version: ""
  swapFree: 6442450944
  swapTotal: 6442450944
  uptime: 79h 49m 42.00s (Approximately 3.29 days)
  variant: ""
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  - journald
  network:
  - bridge
  - macvlan
  - ipvlan
  volume:
  - local
registries:
  search:
  - docker.io
store:
  configFile: /home/dwayne/.config/containers/storage.conf
  containerStore:
    number: 1
    paused: 0
    running: 1
    stopped: 0
  graphDriverName: overlay
  graphOptions: {}
  graphRoot: /home/dwayne/.local/share/containers/storage
  graphRootAllocated: 1081101176832
  graphRootUsed: 17560457216
  graphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Supports shifting: "false"
    Supports volatile: "true"
    Using metacopy: "false"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 4
  runRoot: /run/user/1000/containers
  transientStore: false
  volumePath: /home/dwayne/.local/share/containers/storage/volumes
version:
  APIVersion: 5.6.2
  Built: 1759398423
  BuiltTime: Thu Oct  2 05:47:03 2025
  GitCommit: 9dd5e1ed33830612bc200d7a13db00af6ab865a4
  GoVersion: go1.25.1 X:nodwarf5
  Os: linux
  OsArch: linux/amd64
  Version: 5.6.2

Podman in a container

No

Privileged Or Rootless

None

Upstream Latest Release

Yes

Additional environment details

No response

Additional information

For the "Privileged or Rootless" question...I have tried it both ways with Podman so I just left the default option of "None" selected

[dwaynebradley]

Here is the contents of the tar file:

❯ tar -tvf test-configs.tar
drwxr-xr-x 1001/1001         0 2025-10-20 22:25 configs/
-rw-r--r-- 1002/1002        36 2025-10-20 22:25 configs/test-config-file.txt

Here is the output of the stat commands I mentioned above that I am seeing after running the sample code with Podman:

/ # stat /configs
  File: /configs
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: 7eh/126d        Inode: 351515      Links: 2
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2025-10-21 02:47:56.827825000 +0000
Modify: 2025-10-21 02:25:22.000000000 +0000
Change: 2025-10-21 02:47:56.826763211 +0000
/ # stat /configs/test-config-file.txt
  File: /configs/test-config-file.txt
  Size: 36              Blocks: 8          IO Block: 4096   regular file
Device: 7eh/126d        Inode: 351516      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2025-10-21 02:25:22.000000000 +0000
Modify: 2025-10-21 02:25:22.000000000 +0000
Change: 2025-10-21 02:47:56.826763211 +0000

Here is the output of the stat commands that I am seeing after running the sample code with Docker:

/ # stat /configs
  File: /configs
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: 91h/145d        Inode: 687639      Links: 2
Access: (0755/drwxr-xr-x)  Uid: ( 1001/ UNKNOWN)   Gid: ( 1001/ UNKNOWN)
Access: 2025-10-21 02:52:50.255233409 +0000
Modify: 2025-10-21 02:25:22.000000000 +0000
Change: 2025-10-21 02:52:24.259191323 +0000
/ # stat /configs/test-config-file.txt
  File: /configs/test-config-file.txt
  Size: 36              Blocks: 8          IO Block: 4096   regular file
Device: 91h/145d        Inode: 687640      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1002/ UNKNOWN)   Gid: ( 1002/ UNKNOWN)
Access: 2025-10-21 02:25:22.000000000 +0000
Modify: 2025-10-21 02:25:22.000000000 +0000
Change: 2025-10-21 02:52:24.259191323 +0000

[Honny1]

The logic for managing file ownership during copy operations is inverted between the Docker and Podman APIs. In Docker, copyUIDGID=true preserves the original UID/GID from the archive. Conversely, Podman requires Chown=false to achieve the same result. I am working on fix.

[dwaynebradley]

Thanks for the fix on this one @Honny1 😎

[matejvasek]

I wonder, have you tried also against "normal" Docker?

I tried this against moby 28.5.1 on Fedora and it appears that is behaves the same.
It's contraintuitive but copyUIDGID/--archive does not mean to preserve ownership from the tar stream. It means: apply the main uid/gid of the container. It's insane but that's how things work.

See also: moby/moby#34096

[dwaynebradley]

I just ran it again using Docker on Debian. Here is that version info:

❯ docker version
Client: Docker Engine - Community
 Version:           29.0.0
 API version:       1.52
 Go version:        go1.25.4
 Git commit:        3d4129b
 Built:             Mon Nov 10 21:46:24 2025
 OS/Arch:           linux/amd64
 Context:           default

Server: Docker Engine - Community
 Engine:
  Version:          29.0.0
  API version:      1.52 (minimum version 1.44)
  Go version:       go1.25.4
  Git commit:       d105562
  Built:            Mon Nov 10 21:46:24 2025
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          v2.1.5
  GitCommit:        fcd43222d6b07379a4be9786bda52438f0dd16a1
 runc:
  Version:          1.3.3
  GitCommit:        v1.3.3-0-gd842d771
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

And here is the output of that test with Docker:

docker-copytocontainer-example on  master via 🐹 v1.25.4
❯ ll
drwxr-xr-x    - dwayne 13 Nov 18:33 -I .git
drwxr-xr-x    - dwayne 13 Nov 18:33 -- configs
.rw-r--r-- 1.5k dwayne 13 Nov 18:33 -- go.mod
.rw-r--r-- 8.8k dwayne 13 Nov 18:33 -- go.sum
.rw-r--r-- 1.4k dwayne 13 Nov 18:33 -- main.go
.rw-r--r--  10k dwayne 13 Nov 18:33 -- test-configs.tar

docker-copytocontainer-example on  master via 🐹 v1.25.4
❯ tar -tvf test-configs.tar
drwxr-xr-x 1001/1001         0 2025-10-20 22:25 configs/
-rw-r--r-- 1002/1002        36 2025-10-20 22:25 configs/test-config-file.txt

docker-copytocontainer-example on  master via 🐹 v1.25.4
❯ go run main.go
go: downloading github.com/docker/docker v28.5.1+incompatible
go: downloading github.com/moby/docker-image-spec v1.3.1
go: downloading github.com/docker/go-connections v0.6.0
go: downloading github.com/docker/go-units v0.5.0
go: downloading github.com/opencontainers/image-spec v1.1.1
go: downloading github.com/containerd/errdefs/pkg v0.3.0
go: downloading github.com/containerd/errdefs v1.0.0
go: downloading github.com/distribution/reference v0.6.0
go: downloading github.com/opencontainers/go-digest v1.0.0
go: downloading go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.63.0
go: downloading go.opentelemetry.io/otel/trace v1.38.0
go: downloading go.opentelemetry.io/otel v1.38.0
go: downloading go.opentelemetry.io/otel/metric v1.38.0
go: downloading github.com/felixge/httpsnoop v1.0.4
go: downloading go.opentelemetry.io/auto/sdk v1.1.0
go: downloading github.com/go-logr/stdr v1.2.2
go: downloading github.com/go-logr/logr v1.4.3
{"status":"Pulling from library/alpine","id":"latest"}
{"status":"Pulling fs layer","progressDetail":{},"id":"2d35ebdb57d9"}
{"status":"Downloading","progressDetail":{"current":38341,"total":3802452},"id":"2d35ebdb57d9"}
{"status":"Downloading","progressDetail":{"current":2043584,"total":3802452},"id":"2d35ebdb57d9"}
{"status":"Verifying Checksum","progressDetail":{},"id":"2d35ebdb57d9"}
{"status":"Download complete","progressDetail":{},"id":"2d35ebdb57d9"}
{"status":"Extracting","progressDetail":{"current":65536,"total":3802452},"id":"2d35ebdb57d9"}
{"status":"Extracting","progressDetail":{"current":1376256,"total":3802452},"id":"2d35ebdb57d9"}
{"status":"Extracting","progressDetail":{"current":3802452,"total":3802452},"id":"2d35ebdb57d9"}
{"status":"Pull complete","progressDetail":{},"id":"2d35ebdb57d9"}
{"status":"Digest: sha256:4b7ce07002c69e8f3d704a9c5d6fd3053be500b7f1c69fc0d80990c2ad8dd412"}
{"status":"Status: Downloaded newer image for alpine:latest"}

docker-copytocontainer-example on  master via 🐹 v1.25.4 took 18s
❯ docker ps -a
CONTAINER ID   IMAGE           COMMAND            CREATED         STATUS         PORTS     NAMES
9ef6f6aeade2   alpine:latest   "sleep infinity"   6 seconds ago   Up 4 seconds             copy-uidgid-test

docker-copytocontainer-example on  master via 🐹 v1.25.4
❯ docker exec -ti copy-uidgid-test /bin/sh
/ # ls -la /configs
total 12
drwxr-xr-x    2 1001     1001          4096 Oct 21 02:25 .
drwxr-xr-x    1 root     root          4096 Nov 13 23:43 ..
-rw-r--r--    1 1002     1002            36 Oct 21 02:25 test-config-file.txt
/ #

I ran the exact same test with Docker 28.5.2 on Arch Linux and it behaves the exact same way. CopyUIDGID: true is preserving the ownership from the tar archive. It is not applying ownership the based on the user inside of the container.

[matejvasek]

I ran the exact same test with Docker 28.5.2 on Arch Linux and it behaves the exact same way. CopyUIDGID: true is preserving the ownership from the tar archive. It is not applying ownership the based on the user inside of the container.

@dwaynebradley
OK this is quite surprising for me since my Docker just one patch release below behaves exact opposite.

Would you run this test on your Docker?
https://gist.github.com/matejvasek/859f161d3bb91fed171e218a545d70d7

just adjust the the docker hosts array:
https://gist.github.com/matejvasek/859f161d3bb91fed171e218a545d70d7#file-test-go-L34-L38
to contain only your socket.