[Podman] Re: Idmapped volumes in rootful container with userns=auto

Hello I'm trying to mount a volume in a rootful container using --userns=auto. This is an NFS volme mounted in the host and then onto the container. The container should have write access to the volume, so I'm using the ID mapping options to map the volume owner's UID and GID to 0 in user namespace and the mount parameters. These are the NFS exports: /srv 10.20.3.140/32(rw,fsid=0,no_subtree_check,sync) /srv/home 10.20.3.140/32(rw,sync,nohide,no_subtree_check) The NFS server's /home is bind-mounted on /srv/home. The client mounts the NFS volume on its own /srv: $ mount | grep nfs 10.20.3.137:/ on /srv type nfs4 (rw,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.20.3.140,local_lock=none,addr=10.20.3.137) # ls -l /srv/home total 4 drwxr-x--- 5 local local 4096 Sep 19 17:36 local The "local" user's UID and GID (this user was created on both machines [NFS server and client] with the same UID and GID): # grep local /etc/passwd local:x:1000:1000:local:/home/local:/bin/bash The command I'm using to start the container: # podman run -d --rm --name foo \ --userns=auto:uidmapping=1000:0:1,gidmapping=1000:0:1 \ -v '/srv/home/local:/home/local:idmap=uids=1000-0-1;gids=1000-0-1' \ quay.io/libpod/alpine_nginx This results in the following error: Error: OCI runtime error: crun: mount_setattr `/home/local`: Invalid argument Checking the man page for mount_setattr, there are a bunch of reasons for it to fail with EINVAL, including "MOUNT_ATTR_IDMAP was specified in attr_clr", so my question is, was this supposed to work? If it wasn't, is there a way to achieve a writable NFS volume combined with --userns=auto in a rootful container? I'm using Ubuntu 22.04 with the Kubic packages:

# podman version Client: Podman Engine Version: 4.6.2 API Version: 4.6.2 Go Version: go1.18.1 Built: Thu Jan 1 00:00:00 1970 OS/Arch: linux/amd64 # podman info host: arch: amd64 buildahVersion: 1.31.2 cgroupControllers: - cpuset - cpu - io - memory - hugetlb - pids - rdma - misc cgroupManager: systemd cgroupVersion: v2 conmon: package: conmon_100:2.1.2~0_amd64 path: /usr/libexec/podman/conmon version: 'conmon version 2.1.2, commit: ' cpuUtilization: idlePercent: 99.99 systemPercent: 0.01 userPercent: 0.01 cpus: 48 databaseBackend: boltdb distribution: codename: jammy distribution: ubuntu version: "22.04" eventLogger: journald freeLocks: 2048 hostname: local2 idMappings: gidmap: null uidmap: null kernel: 5.15.0-52-generic linkmode: dynamic logDriver: journald memFree: 263899713536 memTotal: 270361567232 networkBackend: netavark networkBackendInfo: backend: netavark dns: package: aardvark-dns_1.6.0-0ubuntu22.04+obs34.25_amd64 path: /usr/libexec/podman/aardvark-dns version: aardvark-dns 1.6.0 package: netavark_1.3.0-0ubuntu22.04+obs22.9_amd64 path: /usr/libexec/podman/netavark version: netavark 1.8.0-dev ociRuntime: name: crun package: crun_101:1.9-0ubuntu22.04+obs59.11_amd64 path: /usr/bin/crun version: |- crun version 1.9 commit: a538ac4ea1ff319bcfe2bf81cb5c6f687e2dc9d3 rundir: /run/crun spec: 1.0.0 +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +YAJL os: linux pasta: executable: "" package: "" version: "" remoteSocket: path: /run/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: false seccompEnabled: true seccompProfilePath: /usr/share/containers/seccomp.json selinuxEnabled: false serviceIsRemote: false slirp4netns: executable: "" package: "" version: "" swapFree: 0 swapTotal: 0 uptime: 137h 41m 19.00s (Approximately 5.71 days) plugins: authorization: null log: - k8s-file - none - passthrough - journald network: - bridge - macvlan - ipvlan volume: - local registries: search: - docker.io - quay.io store: configFile: /etc/containers/storage.conf containerStore: number: 0 paused: 0 running: 0 stopped: 0 graphDriverName: overlay graphOptions: overlay.mountopt: nodev,metacopy=on graphRoot: /var/lib/containers/storage graphRootAllocated: 8340897792 graphRootUsed: 6129999872 graphStatus: Backing Filesystem: extfs Native Overlay Diff: "false" Supports d_type: "true" Using metacopy: "true" imageCopyTmpDir: /var/tmp imageStore: number: 1 runRoot: /run/containers/storage transientStore: false volumePath: /var/lib/containers/storage/volumes version: APIVersion: 4.6.2 Built: 0 BuiltTime: Thu Jan 1 00:00:00 1970 GitCommit: "" GoVersion: go1.18.1 Os: linux OsArch: linux/amd64 Version: 4.6.2 Thanks in advance, Andre _______________________________________________ Podman mailing list -- podman(a)lists.podman.io To unsubscribe send an email to podman-leave(a)lists.podman.io