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I need to mount a directory in a way that prevents user accessing it. However I need to have access to all attributes (including permission) from root. Is following method safe or is there a way around it:

mkdir /mnt/protect
chmod 700 /mnt/protect
mkdir /mnt/protect/some_dir
mount /dev/sdXn /mnt/protect/some_dir
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up vote 4 down vote accepted

Yes, is should be secure, since any non-root user will not be able to read or enter any directory under /mnt/protect - that is unless you make something stupid like create a hard link to some file under /mnt/protect/ in a place that is accessible to others.

[Edit]: As Maciej has pointed out, it is actually (almost always?) forbidden to create cross-device hardlinks. What you could (but, of course should never) do is create a bind mount to some place under the "protected" filesystem. That would constitute a security breach.

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Note: it is possible to use chmod 700 on the root of the mounted filesystem after it has been mounted. This way you don't have to remember that you want it protected. – Stéphane Gimenez Aug 3 '11 at 9:03
@Stéph I confess that, at first, I didn't get what you mean. But now I see that you propose a different approach to the whole problem - yours works per-filesystem (regardless of the mountpoint) and Maciej's is per-mountpoint (regardless of mounted filesystems). – rozcietrzewiacz Aug 4 '11 at 6:49
Last time I've check it wasn't possible to do hard links to directories or cross-filesystems (of course that are the features of specific filesystems ;) ). – Maciej Piechotka Aug 4 '11 at 20:50
To directories, you can't make a hardlink (that is why I wrote create a hard link to some file. But for cross-filesystem links - good point, Macieju :) – rozcietrzewiacz Aug 5 '11 at 10:31

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