From: "Ludovic Courtès" <ludo@gnu.org>
To: Danny Milosavljevic <dannym@scratchpost.org>
Cc: 36699@debbugs.gnu.org
Subject: [bug#36699] [PATCH 4/4] channels: Reject directories with '..' in '.guix-channel' file.
Date: Thu, 18 Jul 2019 15:44:36 +0200 [thread overview]
Message-ID: <875znzfoe3.fsf@gnu.org> (raw)
In-Reply-To: <20190718115841.4660810e@scratchpost.org> (Danny Milosavljevic's message of "Thu, 18 Jul 2019 11:58:41 +0200")
Hi,
Danny Milosavljevic <dannym@scratchpost.org> skribis:
> On Wed, 17 Jul 2019 01:29:39 +0200
> Ludovic Courtès <ludo@gnu.org> wrote:
>
>> Ludovic Courtès <ludo@gnu.org> skribis:
>>
>> > + (define (sane-directory directory)
>> > + ;; If DIRECTORY contains '..', raise an error; otherwise return it.
>> > + (when (member ".." (string-split directory #\/))
>> > + (raise (condition
>> > + (&message (message "channel sub-directory must not contain '..'"))
>> > + (&error-location (location location)))))
>> > + directory)
>>
>> On second thought, it’s probably kind of useless since the only place
>> where ‘directory’ is used is in the derivation that builds the channel,
>> which is normally running in a chroot:
>>
>> (let* ((subdir #$directory)
>> (source (string-append #$source subdir)))
>> (compile-files source go (find-files source "\\.scm$"))
>> (mkdir-p (dirname scm))
>> (symlink (string-append #$source subdir) scm))
>>
>> So I guess we can drop this patch. Thoughts?
>
> I generally don't like weird name matching like this. The Linux VFS can do
> arbitrary things (which would complicate the situation) to the name tree.
> Even now, a symlink "x" to ".." would work and not be caught. To say nothing
> of what a custom file system could do.
>
> Why single out this one way? It gives the illusion of security.
>
> Containers are better indeed.
Yes, and since that’s what we have, we can forget about this patch.
I definitely agree with everything you wrote; it’s just that the kernel
Linux being what it is, one sometimes have to resort to hacks like this.
Fortunately, that was misguided here, so let’s forget about this. :-)
Ludo’.
next prev parent reply other threads:[~2019-07-18 13:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-16 23:20 [bug#36699] [PATCH 0/4] Strengthen '.guix-channel' file handling Ludovic Courtès
2019-07-16 23:24 ` [bug#36699] [PATCH 1/4] channels: Strictly check the version of '.guix-channel' Ludovic Courtès
2019-07-16 23:24 ` [bug#36699] [PATCH 2/4] channels: Remove unneeded 'version' field of <channel-metadata> Ludovic Courtès
2019-07-16 23:24 ` [bug#36699] [PATCH 3/4] channels: Always provide a <channel-metadata> record Ludovic Courtès
2019-07-16 23:24 ` [bug#36699] [PATCH 4/4] channels: Reject directories with '..' in '.guix-channel' file Ludovic Courtès
2019-07-16 23:29 ` Ludovic Courtès
2019-07-18 9:58 ` Danny Milosavljevic
2019-07-18 13:44 ` Ludovic Courtès [this message]
2019-07-19 9:54 ` bug#36699: [PATCH 0/4] Strengthen '.guix-channel' file handling Ludovic Courtès
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