linux-kernel - Re: [RFC PATCH] afs: Create a mountpoint through symlink() and remove through rmdir()

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Message-ID: <CAHk-=whOAg2EJycA=x=8RzBy3dnDFsgnyxrjREyNu6-8+eTTHA@mail.gmail.com>
Date:   Wed, 19 Feb 2020 17:21:33 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     David Howells <dhowells@...hat.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>, linux-afs@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] afs: Create a mountpoint through symlink() and remove
 through rmdir()

On Wed, Feb 19, 2020 at 4:11 PM David Howells <dhowells@...hat.com> wrote:
>
> If symlink() is given a magic prefix in the target string, turn it into a
> mountpoint instead.
>
> The prefix is "//_afs3_mount:".

That sounds sane.

Your argument that if the prefix is made really long it couldn't be a
valid symlink at all on AFS is fair, but seems somewhat excessive.

The only issue I see with this interface is that you can now create
these kinds of things by untarring a tar-ball etc.

I can see that being both very convenient and a possible security
pain. But I'm assuming that the real security is on the server side
anyway and not just anybody can create arbitrary things like these?

         Linus