synology-guestshares

Shell script using bind mounts to enable subdirectory sharing with another account in Synology DSM

As of Synology DSM 6.1.3, users are unable to control which subdirectories of a share can be viewed by an account. For example, user "guest" can be given read permissions to /volume1/a but not directly /volume1/a/b/c. This can be circumvented by mounting subdirectories as bind mounts into a secondary share your guest user has appropriate permissions for.

Requirements

• Dataset containing a directory or subdirectory that you want to provide a guest
• Share your guest user has permissions for, guestshare for purposes of this script (Control Panel > Shared Folder > Create)
• SSH enabled via DSM (Control Panel > Terminal & SNMP > Enable SSH service checkbox)

Usage

1. Copy script to usable location on the Synology
2. Set guestshare and mountlist vars at the top of the script to the appropriate names of your shares
3. Open SSH session and su to root (sudo su -)
4. Add share(s) for guest. This will write the full path to $mountlist and the bind mount will now be visible.

• # guestshares.sh addshare /volume1/data/Photos "/volume1/data/a/b c"

5. Setup triggered tasks in DSM for mounting/unmounting on boot and shutdown. (Control Panel > Task Scheduler > Create > Triggered Task > User-defined script)

• Set event to Boot-up and User-defined script to /path/to/guestshares.sh mount
• Set event to Shutdown and User-defined script to /path/to/guestshares.sh unmount