Re: [Caml-list] Securely loading and running untrusted modules

[Richard Jones <rich@annexia.org>]

On Tue, Apr 05, 2005 at 04:09:05PM +0200, Alex Baretta wrote:
> alex@alex:~$ ocaml
>         Objective Caml version 3.08.2
> 
> # external pizza : 'a -> 'b = "%identity";;
> external pizza : 'a -> 'b = "%identity"
> # pizza 1 = "pasta";;
> Segmentation fault

Dynlink allows me to specify that modules can't use unsafe features,
so such declarations wouldn't be permitted.

A much more serious problem which I've just found is that _any_ module
(even the empty module) seems to require Pervasives.  Thus it seems to
be impossible to create any OCaml code which could be loaded by
Dynlink where Dynlink.allow_only does not specify "Pervasives".

rich@arctor:/tmp$ rm test_module.ml 
rich@arctor:/tmp$ touch test_module.ml
rich@arctor:/tmp$ ocamlc -c test_module.ml 
rich@arctor:/tmp$ ocamlobjinfo test_module.cmo 
File test_module.cmo
  Unit name: Test_module
  Interfaces imported:
        71f888453b0f26895819460a72f07493        Pervasives
        f7db4d58568a6e5a2cfe62ef59a52df1        Test_module
  Uses unsafe features: no
rich@arctor:/tmp$ ./test
Dynlink: no implementation available for Pervasives

Rich.

-- 
Richard Jones, CTO Merjis Ltd.
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