Re: Electrolysis security

Rob Arnold <[email protected]> wrote:
> > The equivalent is to open the file read-only and then transmit it to
> > the content process with a SCM_RIGHTS (iirc) message on a local
> > domain socket.
> 
> Thanks. Is there a good source of documentation on these APIs? I'm
> looking for an equivalent to MSDN. Bonus points if it covers other
> unixes.

I don't know a consolidated online guide-and-reference equivalent to
MSDN for the Unix APIs.  The GNU libc manual [1] is very good for what
it covers, and generally good at indicating what is portable and what
is GNU-specific.  The Open Group has the text of its various standards
online (free registration required) at [2].  Unfortunately, neither of
these covers transmission of file descriptors between processes.  The
Linux and FreeBSD manpages [3,4] do cover it but not very clearly.

W. Richard Stevens' books [5] are almost certain to cover it, but
that's $170 worth of dead trees. :-/

> > I'd be much more worried about finding ways to disable
> > socket(AF_INET, ...) and friends, and to cut off access to most
> > absolute paths without breaking the C library.
> 
> 
> Right. This is a challenge on Windows (XP only I think) too. Once all
> the shared libraries are loaded, is there any reason that we can't
> chroot the child process (on unix...Windows doesn't have chroot)?

It's a privileged operation on unix, unfortunately.  And there are a
bunch of C library functions that expect to be able to get at files
in /etc, /dev, and /lib, even after the dynamic loader is done.

FreeBSD has jail(), which still requires copying a bunch of stuff into
a private directory tree, but is a lot more flexible than chroot().  On
Linux we might be able to do something with SELinux.  I don't know
about Darwin.

zw

[1] http://www.gnu.org/software/libc/manual/
[2] http://www.opengroup.org/bookstore/catalog/t_c.htm
[3] http://www.kernel.org/doc/man-pages/online/pages/man3/cmsg.3.html
[4] http://www.freebsd.org/cgi/man.cgi?query=recv&sektion=2
[5]
http://www.amazon.com/Unix-Network-Programming-Addison-Wesley-Professional/dp/0131411551/