Re: autoclean mode for tmpfs

[Eric Haszlakiewicz <erh%nimenees.com@localhost>]

On Sun, Aug 07, 2011 at 04:51:39PM +0000, David Holland wrote:
> On Sun, Aug 07, 2011 at 12:11:49PM -0400, Mouse wrote:
>  > However, since there's no way to make rmdir(2) use NOFOLLOW, we
>  > have to either leave directory structure in place or risk removing an
>  > attacker's choice of empty directories.
> ?
> 
> valkyrie% ls -l
> total 4
> drwx------  2 dholland  notmp  512 Aug  7 12:32 bar
> lrwx------  1 dholland  notmp    3 Aug  7 12:32 baz -> bar
> valkyrie% rmdir baz
> rmdir: baz: Not a directory
> Exit 1

My guess for steps to create the problem is:

% mkdir /tmp/foo/bar
% make-lots-of-files-in-dir /tmp/foo/bar
% run-job-that-slows-down-the-system
% wait-for-tmp-cleanup-to-start
% mv /tmp/foo /tmp/foo2
% ln -s /some/path /tmp/foo
... and the tmp cleanup does a "rmdir /tmp/foo/bar", which is actually 
 /some/path/bar instead.

eric