Geo. wrote:
> I think when evaluating how dangerous something is to the internet you have
> to look at how it's used and how much risk that creates.
>
> For example, allowing users to upload and execute any C executable file to a
> public web server can prove to be quite dangerous.
>
> I think the same can be said for allowing PHP on a public web server, you
> have just allowed anyone with a website to compromise the entire machine.
>
Plugging my own product, but what the hell, it is open source :)

AppArmor http://opensuse.org/Apparmor is an application security
container technology for Linux. It lets you create application profiles
(policies) that define the files that the application can read, write,
and execute. It lets you do this per-application, so you actually could
allow users to upload arbitrary C/binary programs and expect them to
behave as you specified. It provides an inheritance model so that you
can't escape from this jail by exec'ing something fun: the child is
controlled by policy too.

And for confining PHP (and PERL code run by mod_perl, and any other
language interpreted in-place by Apache) AppArmor provides a change_hat
API call and a mod_apparmor module for Apache, so that you can have
AppArmor-style profiles wrapped around individual PHP pages and mod_perl
scripts, even though they never appear in the process table.

If you find yourself between the rock of having to run some PHP or PERL
code and a hard place of not trusting that code, try confining it with
AppArmor, so that if/when the code screws up, it can only screw itself.

Crispin

--
Crispin Cowan, Ph.D. http://crispincowan.com/~crispin/
Director of Software Engineering, Novell http://novell.com

[ reply ]