I'm running an Ubuntu guest VirtualBox instance. I have a host folder web-server being shared with the guest. On the guest, there are two users which need writable access to the shared folder: the daemon user www-data, and a regular SSH login user which I'll call jdoe, who are both members of the group I'll call www-users

On the host, the folder looks like:

$ ls -al /Users/jdoe/web-server
drwxrwsr-x  14 jdoe  staff   448 Jun 19 11:04 .

On the guest, the folder is mounted with:

$ mount -t vboxsf -ogid=www-users web-server /usr/share/host/web-server

And running mount shows:

web-server on /usr/share/host/web-server type vboxsf (rw,nodev,relatime)

I've also attempted to add jdoe to the vboxsf group; jdoe has the following groups:

jdoe adm sudo vboxsf ssl-cert www-users

While the setup appears to work on Windows and Ubuntu hosts, on OS X the guest user does not have writable access to the folder. The permissions on the guest appear as:

$ ls -al /usr/share/host/web-server
drwxrwxr-x 1 root www-users  448 Jun 19 11:04 .

But when logged in as jdoe, I cannot write to the folder:

$ touch /usr/share/host/web-server/foo
touch: cannot touch '/usr/share/host/web-server/foo': Permission denied

If I change the mount to -ouid=jdoe,gid=www-users, then jdoe can write to it, and if I change it to -ouid=www-data,gid=www-users, then www-data can write to it. In either case, other members of the www-users cannot write to the folder.

Another note, I cannot rely on VirtualBox auto-mount, because this needs to work as it does in production, where drives get mounted on the fly.

  • Did you try using rw option of mount? man mount.
    – ajeh
    Jun 19 '18 at 18:24
  • On the guest, what groups is jdoe a member of? Jun 19 '18 at 19:07
  • I verified the mount is mounted with rw by default and I've edited the question with the groups: jdoe adm sudo vboxsf ssl-cert www-users
    – Rich Remer
    Jun 19 '18 at 19:23
  • (As an alternative to whatever other answers are given) I had similar problems in the past and now I use vagrant to set up VMs on OS X and everything is much easier as it takes care of mounting etc and I use shell scripts to sort out the details like users and dir access. Just in case you can't get any further with your problem and start looking for ways around.
    – ian
    Jun 23 '18 at 21:28
  • Please can you specify the version(s) of Ubuntu you are testing, to date this question? Since this seems so weird, I would suggest mentioning the version number of VirtualBox as well.
    – sourcejedi
    Jun 24 '18 at 11:47

Can you try this ?

mount -t vboxsf -ouid=root,gid=www-users,fmode=664,dmode=775 web-server /usr/share/host/web-server
  • Thanks. This worked for me, for when nginx's root is a mount point from virtualbox
    – Ryan
    Mar 5 '19 at 2:42
  • Thank you, indeed the part fmode=664,dmode=775 fixed a similar issue for me when I was unable to pull git updates on a shared folder.
    – Frederic
    Sep 12 '19 at 11:19

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