[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Wed, 1 Oct 2014 00:04:35 +0400
From: gremlin@...mlin.ru
To: oss-security@...ts.openwall.com
Subject: Re: Healing the bash fork
On 30-Sep-2014 11:30:52 +0200, Florian Weimer wrote:
>>>> What is the motivation to not store executable code (functions)
>>>> differently from standard variables?
>>> What would you use for such a store, considering the environment
>>> is the only portable way to pass this information from one
>>> process to another in the general case, and support the current
>>> set of use cases?
>> C.O. to the rescue: temporary file.
> You cannot use a named temporary file because the creator does
> not know its required lifetime. That's a challenge all solutions
> not based on the process environment will face.
Creator doesn't, but (grand)*child does: open it, unlink it, read it,
close it. Once the shell needs to run something, it can create a new
file with exported stuff. Garbage collection should be thought of,
but it's out-of-scope for this discussion.
> Theoretically, you could pass an unnamed temporary file via a file
> descriptor, and communicate the descriptor number in some safe way
> (but what's that, if you don't trust the environment?).
Generally, the environment is unsafe because it may be filled by any
(grand)*parent process.
> But that's going to be far less interoperable than what we currently
> have, and barely more secure.
If the attacker needs to create the file AND to fill the environment
variable to succeed, that more likely is more secure. Or am I missing
something?
>> If one shell instance needs to pass some functions to another,
>> it could dump those functions to a temporary file and pass the
>> --load (or, better, --load-functions) options with a filename
>> parameter.
> We need to keep support exporting functions to grandchildren
> through non-bash processes (that is, bash - some-other-program
> - bash).
Hmmm... Well, requiring both a file and an environment variable may
be a good solution. Or not.
--
Alexey V. Vissarionov aka Gremlin from Kremlin <gremlin ПРИ gremlin ТЧК ru>
GPG: 8832FE9FA791F7968AC96E4E909DAC45EF3B1FA8 @ hkp://keys.gnupg.net
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
