Consider the following union mount:

mount -t overlay -o lowerdir=/.pre-foo/lower,upperdir=/.pre-foo/upper,workdir=/.pre-foo/work overlay /foo

I would like to obfuscate that /.pre-foo to minimize the chance of some process to modify my underlying folders while the union is mounted. I could get it with the following "recursive" mount:

mount -t overlay -o lowerdir=/foo/lower,upperdir=/foo/upper,workdir=/foo/work overlay /foo

My question is: Is this safe? Is there any security and/or performance risk in mounting an overlay "recursively"?

  • yes. its fine. do it.
    – mikeserv
    Oct 13, 2015 at 17:34
  • 1
    I believe the question might be more clearly stated as follows: (1) Can lowerdir, upperdir and workdir be nested inside the mount point (/foo, in this case)? (2) Is such nesting secure and performant? (3) After the mount is performed, will the nested lowerdir, upperdir and workdir be hidden, protected, and only accessible through the "view" provided by the overlay?
    – mpb
    Dec 14, 2016 at 18:42


You must log in to answer this question.

Browse other questions tagged .