I am trying to give all Users on a system their own writable copy of a root-owned directory, and OverlayFS sounds like the tool for the job, but I am finding it not as straightforward as it sounded at first.
First, the setup:
> mkdir upper work merged merged-user
> sudo mkdir -p lower/path/to
> sudo touch lower/path/to/file
> ls -l
drwx------ 2 user group 4096 Aug 10 00:00 merged
drwx------ 2 user group 4096 Aug 10 00:00 merged-user
drwxr-xr-x 3 root root 4096 Aug 10 00:00 lower
drwx------ 2 user group 4096 Aug 10 00:00 upper
drwx------ 2 user group 4096 Aug 10 00:00 work
The goal at the end is to allow User user to write to any directory or path in the merged or merged-user mount point.
First attempt, with mount:
> sudo mount -t overlay overlay -o "lowerdir=$PWD/lower,upperdir=$PWD/upper,workdir=$PWD/work" merged
> ls -l merged/path/to
total 4
-rw-r--r-- 1 root root 5 Aug 10 00:00 file
> echo me > merged/path/to/file
sh: merged/path/to/file: Permission denied
I get it; at the kernel level, OverlayFS isn't touching the permissions, so the merged directory doesn't have the permissions setup I would like. Enter fuse-overlayfs:
fuse-overlayfs -o "lowerdir=lower,upperdir=upper,workdir=work,squash_to_uid=$(id -u)" merged-user
> ls -la merged-user/
total 8
drwx------ 3 user group 4096 Aug 10 00:00 .
drwxr-xr-x 3 root root 4096 Aug 10 00:00 path
> echo me > merged-user/path/to/file
sh: merged-user/path/to/file: Permission denied
Still permission denied, even with the squash_to_uid option. Am I missing some other parameter that would enabled merged or merged-user to appear as the User's own directories?
