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Date: Sun, 6 Oct 2013 00:24:51 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rob Landley <rob@landley.net>, "Eric W. Biederman" <ebiederm@xmission.com>,
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        Andy Lutomirski <luto@amacapital.net>
Subject: Re: [RFC][PATCH 0/3] vfs: Detach mounts on unlink.
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On Sat, Oct 05, 2013 at 04:17:55PM -0700, Linus Torvalds wrote:
> On Sat, Oct 5, 2013 at 4:07 PM, Rob Landley <rob@landley.net> wrote:
> >
> > A todo item I've had _forever_ is fixing chroot() to not be broken so that
> > you can trivially break out of a chroot via:
> 
> What drugs are you on?
> 
> Your example is moronic, and against all _documented_ uses of chroot.

... and even fixing that example (chroot *can* be escaped, if you can
call chroot(2) - mkdir /foo, chdir /, chroot /foo, chroot .. and you are out)
the whole thing is idiocy - chroot() is not and has never been root-proof
and anybody expecting it to be has failed to read any number of FAQs out
there.