Make lxc-docker a privileged container: unprivileged can't NFS-mount at all #28

Merged

beatzaplenty merged 1 commits from worktree-fix-container-dns-search-domain into main

2026-07-21 08:50:14 +00:00

Author	SHA1	Message	Date
beatzaplentyandClaude Sonnet 5	6b09a808ed	Make lxc-docker a privileged container: unprivileged can't NFS-mount at all Check NixOS configurations / eval-hosts (pull_request) Successful in 10m33s Details The kernel's NFS client filesystem doesn't set FS_USERNS_MOUNT, so mounting NFS from inside any non-init user namespace -- exactly what an unprivileged LXC container's UID-mapped root runs in -- is rejected at the VFS layer with EPERM, regardless of Proxmox's mount=nfs;nfs4 container feature (which only patches the AppArmor layer). Confirmed live on the redeployed lxc-docker container: TCP to the NFS server's port 2049 succeeds, the server's export table matches the container's IP, and mount.nfs: Operation not permitted still fires immediately with no corresponding denial anywhere in the server's own logs -- a kernel-level rejection that no amount of DNS/ automount/export tweaking (this branch's earlier commits) could ever fix. modules/platforms/lxc.nix now keys proxmoxLXC.privileged off hostName ("docker" -> true) rather than a blanket false, since build-types/docker.nix is also composed for linode-docker/proxmox-docker, which don't import proxmox-lxc.nix at all -- setting this option there would break their eval. create-proxmox-resource.sh reads the value back via a new flake_target_lxc_privileged helper instead of hardcoding --unprivileged 1, so the two stay in sync automatically for every lxc-* target. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01T48qgH3VTvs8wvwj44FEbE	2026-07-21 05:57:06 +00:00

Author

SHA1

Message

Date

beatzaplentyandClaude Sonnet 5

6b09a808ed

Make lxc-docker a privileged container: unprivileged can't NFS-mount at all

Check NixOS configurations / eval-hosts (pull_request) Successful in 10m33s

Details

The kernel's NFS client filesystem doesn't set FS_USERNS_MOUNT, so mounting
NFS from inside any non-init user namespace -- exactly what an unprivileged
LXC container's UID-mapped root runs in -- is rejected at the VFS layer
with EPERM, regardless of Proxmox's mount=nfs;nfs4 container feature (which
only patches the AppArmor layer). Confirmed live on the redeployed lxc-docker
container: TCP to the NFS server's port 2049 succeeds, the server's export
table matches the container's IP, and mount.nfs: Operation not permitted
still fires immediately with no corresponding denial anywhere in the
server's own logs -- a kernel-level rejection that no amount of DNS/
automount/export tweaking (this branch's earlier commits) could ever fix.

modules/platforms/lxc.nix now keys proxmoxLXC.privileged off hostName
("docker" -> true) rather than a blanket false, since build-types/docker.nix
is also composed for linode-docker/proxmox-docker, which don't import
proxmox-lxc.nix at all -- setting this option there would break their eval.
create-proxmox-resource.sh reads the value back via a new
flake_target_lxc_privileged helper instead of hardcoding --unprivileged 1,
so the two stay in sync automatically for every lxc-* target.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T48qgH3VTvs8wvwj44FEbE

2026-07-21 05:57:06 +00:00