Hello !

Getting a bit annoyed with permission issues with samba and sshfs. If someone could give me some input on how to find an other more elegant and secure way to share a folder path owned by root, I would really appreciate it !

Context

  • The following folder path is owned by root (docker volume):

/var/lib/docker/volumes/syncthing_data/_data/folder

  • The child folders are owned by the user server

/var/lib/docker/volumes/syncthing_data/_data/folder

  • The user server is in the sudoers file
  • Server is in the docker groupe
  • fuse.confhas the user_allow_other uncommented

Mount point with sshfs

sudo sshfs server@10.0.0.100:/var/lib/docker/volumes/syncthing_data/_data/folder /home/user/folder -o allow_other

Permission denied

Things I tried

  • Adding other options like gid 0,27,1000 uid 0,27,1000 default_permissions…
  • Finding my way through stackoverflow, unix.stackexchange…

Solution I found

  1. Making a bind mount from the root owned path to a new path owned by server

sudo mount --bind /var/lib/docker/volumes/syncthing_data/_data/folder /home/server/folder

  1. Mount point with sshfs

sshfs server@10.0.0.100:/home/server/folder /home/user/folder

Question

While the above solution works, It overcomplicates my setup and adds an unecessary mount point to my laptop and fstab.

Isn’t there a more elegant solution to work directly with the user server (which has root access) to mount the folder with sshfs directly even if the folder path is owned by root?

I mean the user has root access so something like:

sshfs server@10.0.0.100:/home/server/folder /home/user/folder -o allow_other should work even if the first part of the path is owned by root.

Changing owner/permission of the path recursively is out of question !

Thank you for your insights !

  • @redcalcium
    3•3 months ago

    The easiest setup I tried so far is to simply put your docker container’s volume on an external path, e.g. /mnt/hdd1/some-directory, instead of putting it in the standard docker location (/var/lib/docker/volume). You’ll have full control over ACL on those custom paths.

    • @N0x0n@lemmy.mlOP
      2•3 months ago

      Heyyy !

      Thank you, that’s actually a good workaround ! Haven’t though about it !

      In case you’re interested @Successful_Try543@feddit.de pointed to the right direction with sshfs.

      sshfs server@10.0.0.100:/var/lib/docker/volumes/syncthing_data/_data/folder /home/user/folder/ -o sftp_server="/usr/bin/sudo /usr/lib/openssh/sftp-server"

      Adding the following line in sudoers file after @includedir /etc/sudoers.d:

      server ALL = NOPASSWD: /usr/lib/openssh/sftp-server

      This works, even tough I’m not sure if this is actually good security practice :/.

      I will keep in mind your solution if I find out that this workaround is bad practice. What’s your opinion on this?

      Thank you !

      • @redcalcium
        3•3 months ago

        So the workaround is running the SFTP process as root?

        Why not run the SFTP server as a docker container as well (e.g. with https://hub.docker.com/r/atmoz/sftp/ )? You can mount the same volume in the SFTP container, and have it listen on some random port. Just make sure to configure the SFTP container to use the same uid:gid as the one used in the syncthing container to avoid file permission issues.

        • @Successful_Try543@feddit.de
          2•3 months ago

          The solutions you’ve proposed definitely are more elegant and I’d prefer either of these over my quick and dirty solution.

          The question is: How frequently is this needed? If its on a regular basis, then the workaround using bind or selecting a different storage path are preferable. If it’s needed even more frequently, setting up the Docker SFTP container is an acceptable extra work.

          • @redcalcium
            3•3 months ago

            In that case, perhaps replacing -o sftp_server="/usr/bin/sudo /usr/lib/openssh/sftp-server" with -o sftp_server="/usr/bin/sudo -u <syncthing_user> /usr/lib/openssh/sftp-server" is a good compromise?

            • @N0x0n@lemmy.mlOP
              1•3 months ago

              Hey thank you for the nice tip ! This looks actually promising and exactly what I needed !

              Going with this route, which seems way more secure. Fiddling with sudoers permissions seems a bad idea in the first place !

              Thank you very much 👋