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I'm experimenting with different union/overlay filesystem types. I've found unionfs-fuse package in Ubuntu which allowed me to use unionfs mount command as non-root user. But it seems aufs, which is created to provided similar options as unionfs, cannot be used as non-root user. I need to give sudo password for aufs mount.

Can I use aufs without giving root password?

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In researching this the answer appears to be: no.

  • It's not just apparent from the documentation, it's inherent in the way it works. – Gilles Aug 13 '18 at 1:25
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    @Gilles - I know that, I was trying to show the OP how to research it for themselves. – slm Aug 13 '18 at 1:26
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    I've actually gone through at the man page of aufs and researched other pages and arrived at the conclusion that the answer is no. But wanted to get a definited answer. Thank you for the answer and time – Anwar Aug 13 '18 at 11:48
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The command to mount an aufs filesystem is mount. The filesystem type (shown in /proc/mounts or in the output of mount with no arguments) is aufs, not fuse. This shows that aufs is a filesystem of its own, it doesn't use FUSE. It's implemented with its own kernel driver, not through the FUSE kernel driver.

If you want to use aufs as a non-root user, root has to allow it. There are several mechanisms for that, the simplest being to add some lines in /etc/fstab.

Note that you should review those lines carefully, because they may well allow users to bypass your system's security. Anyone can use FUSE because the FUSE kernel driver enforces restrictions on what the user code can do: non-root users can only mount onto a directory that they own, and can only expose files that they own. The aufs driver does not enforce any such restriction, which both makes it more powerful and difficult to delegate.

There's no mechanism in /etc/fstab to allow users to specify different mount options. This is by design: many mount options would allow users to bypass the system's security. It would be complicated to figure out which options are safe, and the mount command (which parses /etc/fstab) doesn't try. If you, as the administrator, want to allow different sets of mount options, then you need to list them all.

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