From: Eric Abrahamsen <eric@ericabrahamsen.net>
To: 28489@debbugs.gnu.org
Subject: bug#28489: Acknowledgement (27.0.50; eieio-persistent slot type validation should be a bit smarter)
Date: Fri, 29 Sep 2017 13:31:59 -0700 [thread overview]
Message-ID: <87vak16ybk.fsf@ericabrahamsen.net> (raw)
In-Reply-To: <87lglcn8dt.fsf@ericabrahamsen.net>
Noam Postavsky <npostavs@users.sourceforge.net> writes:
> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>> Essentially it is validating twice, both before and after the actual
>> objects are created. I don't have a very firm grasp of all the code
>> involved, but in principle I would prefer just to eval all object
>> construction forms regardless, and then let it blow up at "real"
>> validation time -- it was going to blow up anyway.
>
> Hmm, yeah, it does look the prevalidation is mostly redundant work. The
> docstring of eieio-persistent-convert-list-to-object mentions malicious
> code, perhaps the prevalidation should be with unsafep (i.e., don't try
> to typecheck anything, just make sure it's safe to eval). This would
> require that object constructors could be marked safe though.
That sounds like the right solution. I've never looked at
unsafep.el, and don't know exactly how it works, but in principle I
think object creation should be "safe". Of note:
1. Strings read from the persistence file are already stripped of
properties.
2. Slot values are simply validated by type. I don't think eval is
called anywhere, though I'd be happy to try to make sure of this.
3. Object creation could run malicious code *if* someone had overridden
`initialize-instance' or `shared-initialize', and injected random
hard-drive-destroying code. But I don't think this malicious code
could be included in a persistence file itself (that's worth looking
in to).
I don't know how close that gets us to "safe".
>> But again, my patch or something like it would be enough to get
>> everything working as advertised.
>
> Right. I think your patch is probably fine, though a few tests might a
> good idea too.
I might as well write tests that exercise the whole eieio-persistent
round-trip: create a few test objects, write them to a tmp file, and
read them back as objects.
Thanks,
Eric
next prev parent reply other threads:[~2017-09-29 20:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-18 0:43 bug#28489: 27.0.50; eieio-persistent slot type validation should be a bit smarter Eric Abrahamsen
[not found] ` <handler.28489.B.150569546424990.ack@debbugs.gnu.org>
2017-09-26 20:22 ` bug#28489: Acknowledgement (27.0.50; eieio-persistent slot type validation should be a bit smarter) Eric Abrahamsen
2017-09-27 0:05 ` Noam Postavsky
2017-09-27 16:39 ` Eric Abrahamsen
2017-09-28 2:23 ` Noam Postavsky
2017-09-28 5:02 ` Eric Abrahamsen
2017-09-29 0:35 ` Noam Postavsky
2017-09-29 20:31 ` Eric Abrahamsen [this message]
2017-09-30 0:57 ` Noam Postavsky
2017-09-30 18:05 ` Eric Abrahamsen
2017-09-30 21:58 ` Noam Postavsky
2017-09-30 23:30 ` Eric Abrahamsen
2017-10-14 12:13 ` Eric Abrahamsen
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