mount –bind Other User as Myself

bind-mountmount

I'm using fstab to bind a folder that belongs to another user in one of my own directories. I know that I can map users when I mount an SSHFS, I've been doing some research and I can't find a mount --bind equivalent.

Is there any way I can mount another user's folder and files as my own?

Update: It doesn't necessarily have to be mount --bind. It just has to do something similar while mapping users, and can be done on startup.

Best Answer

You can't do that with the Linux bind mount kernel feature. But you can do it with the FUSE filesystem bindfs. Bindfs is slower than bind mounts and doesn't pass extended attributes, but on the flip side, it can be used by non-root users and on Unix variants other than Linux, and most importantly for you, allows simple transformations of ownership and permissions.

bindfs -u cqqrstoo ~bob/stuff ~cqqrstoo/bobs-stuff

In /etc/fstab, that would translate to:

bindfs#/home/bob/stuff /home/cqqrstoo/bobs-stuff fuse force-user=cqqrstoo 0 0

Related Solutions

SSH – How to Mount a Remote SSHFS Directory on an Inaccessible Client Machine

This was easier than I thought!

All one has to do is bind the port 2048 of serverC to a port on pcA. For simplicity I use the same port number 2048:

user@pcA $ ssh -L 2048:localhost:2048 user@serverC

One needs to keep this terminal window open.

Then, mounting the directory pcB:/home/user locally on pcA looks like this:

sshfs -o port=2048 user@localhost:/home/user/ /mnt/pcB

Nice side-effect: This means you can also use efficient X-server connections, e.g. freeNX or vnc to retrieve a display of pcB. Just connect to localhost:2048 and use the correct credentials (user name/password) for machine pcB!

If you don't want to have to keep a terminal open for the connection, you use:

ssh -NfL 2048:localhost:2048 user@serverC

Note that doing this might violate your employers'/organizational security policy, so make sure to get appropriate permissions.

Bind mounting and df output

A bind mount is equivalent to the original. There isn't one that's marked as the original and one that's marked as a copy. Bind mounts are like hard links in this respect, not like symbolic links.

Since GNU coreutils 8.21 (if I read the changelog correctly), df strives to report each filesystem only once. Older versions included one entry per non-ignored mount point, so a bind mount would result in multiple entries. df shows the latest mount point for each filesystem, as far as it can determine. In your case, df reports /opt, not /data, because /opt was added last.

Pass the option -a to get even recent coreutils to report all entries for each filesystem. This also causes filesystems that would normally be ignored to be listed, if you don't pass a path argument. If you do pass a path argument, I think df never reports anything but the latest mount point.

If you don't want to alias df to something else, you'll either have to replace df by a custom implementation or have to live with df reporting something different from what you'd like. If you need the earliest mount point rather than the latest one, a sane solution would be to call df -a and retain only the first match for the device that you're interested in.

Best Answer

Related Solutions

SSH – How to Mount a Remote SSHFS Directory on an Inaccessible Client Machine

Bind mounting and df output

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