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
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