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From Jason Smith <...@iriscouch.com>
Subject Re: Branch to switch from SpiderMonkey to Node.js
Date Tue, 05 Feb 2013 08:39:14 GMT
Can we please discuss this when I have running code to talk about?

I mentioned my idea but I have not tried it yet. I agree with Benoit,
forking subprocesses feels like a hack. But without working code, it is
hard to judge cost vs. benefit.


On Tue, Feb 5, 2013 at 7:26 AM, Benoit Chesneau <bchesneau@gmail.com> wrote:

> On Mon, Feb 4, 2013 at 6:58 PM, Jan Lehnardt <jan@apache.org> wrote:
> >
> > On Feb 4, 2013, at 18:47 , Benoit Chesneau <bchesneau@gmail.com> wrote:
> >
> >> On Mon, Feb 4, 2013 at 12:10 PM, Jan Lehnardt <jan@apache.org> wrote:
> >>>
> >>> On Feb 4, 2013, at 11:53 , Benoit Chesneau <bchesneau@gmail.com>
> wrote:
> >>>
> >>>> On Thu, Jan 31, 2013 at 5:54 PM, Jason Smith <jhs@iriscouch.com>
> wrote:
> >>>>>
> >>>>> On Thu, Jan 31, 2013 at 4:34 PM, Benoit Chesneau <
> bchesneau@gmail.com>wrote:
> >>>>>
> >>>>>>
> >>>>>> A javascript engine doesn't expose any IO par default. The
> **framework**
> >>>>>> nodejs is, this is all the point. I'm quite interested by the
> existing
> >>>>>> solutions to sandbox nodejs, do you know some projects that
does it?
> >>>>>>
> >>>>>
> >>>>> Correct. I am attempting to build something which satisfies your
> >>>>> description: no i/o; i/o is not even possible.
> >>>>>
> >>>>> *How* is it implemented? Well, it doesn't matter whether we use
> Node.js or
> >>>>> couchjs/SM or couchjs/v8. What matters is we feel confident about
> security.
> >>>>> And of course, I agree, if we cannot achieve good security, then
> that is a
> >>>>> show stopper.
> >>>>>
> >>>>> Here is my current plan for sandboxing CouchJS. (Thanks to Isaac
for
> his
> >>>>> tips.)
> >>>>>
> >>>>> When it is time to evaluate some code:
> >>>>>
> >>>>> 1. Set up an object with safe variable bindings: safe_context
> >>>>> 2. fork()
> >>>>> 3. Child process runs vm.runInNewContext(safe_context)
> >>>>> 4. Child process communicates to the parent over stdio, through
the
> >>>>> approved safe_context functions
> >>>>>
> >>>>> The subprocess can also give extra sandboxing, such as chroot()
if
> >>>>> available.
> >>>>>
> >>>>> Yes, this causes two processes per instantiation; however I think
the
> >>>>> parent might only be short-lived, setting up the security, then
> exiting.
> >>>>> The grandchild can talk to Erlang over stdio.
> >>>>>
> >>>>> That is my plan. No idea how well it will work.
> >>>>>
> >>>>> --
> >>>>> Iris Couch
> >>>>
> >>>>
> >>>>
> >>>> Too much kool-aid imo :)
> >>>>
> >>>> This is not that it can't work. But are you seriously considering to
> >>>> have a main couchjs process maintaining the STDIO channel and spawn
a
> >>>> new OS Process for a view (which what does  `vm.runInNewContext`)? The
> >>>> memory and latency cost can became very important, and i don't count
> >>>> the chrooting cost especially if run this context on each indexation
> >>>> batch or shows, lists and views requests. + the extra fds created by
> >>>> each child contexts.
> >>>
> >>> Alternatively, if the above works and is necessary (modulo Klaus’s
> >>> research), we live with the hit until we get to rewrite the view
> protocol
> >>> at which point we can make it 1 Erlang process -> 1 node process for
> >>> dispatching -> N Node processes for indexing.
> >>
> >> I don't think it is necessary at all to use so many *OS* process at
> >> all for our purpose. And I am really worried by such solution.There is
> >> a reason why people don't try to launch too much OS processes on the
> >> system,  There is a reason why we are using systems like Erlang.
> >>
> >> I guess runInContext would work, with a custom `require` function to
> >> include modules (to specifically forbid IO) . According to the doc the
> >> context doesn't share anything, which is what we want. Also if we are
> >> going for node i would prefer to start with a straight forward
> >> solution and not introduce any new behaviours.
> >
> > I suggested 1 extra node process in total, if at all, as an alternative,
> > if the thing Klaus and you outline doesn’t work.
> >
> Why doesn't it work?
>
> runInNewContext would imply to launch one new context / view if you
> want to really run it sandboxed.
>
> "vm.runInNewContext compiles code, then runs it in sandbox and returns
> the result.".
>
> I don't see any other way since you can't recycle a context in this
> case. Having another I/O for this context wil be even uglier. In that
> case you would have STDIO -> CHILD -> STDIO -> CHILD . Without
> counting the memory usage it will add more latency than we have right
> now. The more I think about that the more I'm reluctant to support
> such solution.
>
> - benoît
>



-- 
Iris Couch

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