Re: [PATCH 0/4] reST-directive kernel-cmd / include contentent from scripts

[Jonathan Corbet <corbet@lwn.net>]

On Sat, 22 Oct 2016 08:56:29 -0200
Mauro Carvalho Chehab <mchehab@infradead.org> wrote:

> The security implications will be the same if either coded as an
> "ioctl()" or as "syscall", the scripts should be audited. Actually,
> if we force the need of a "syscall" for every such script, we have
> twice the code to audit, as both the Sphinx extension and the perl
> script will need to audit, increasing the attack surface.

Just addressing this one part for the moment.  Clearly I've not explained
my concern well.

The kernel-cmd directive makes it possible for *any* RST file to run
arbitrary shell commands.  I'm not concerned about the scripts we add, I
hope we can get those right.  I'm worried about what slips in via a tweak
to some obscure .rst file somewhere.

A quick check says that 932 commits touched Documentation/ since 4.8.  A
lot of those did not come from either my tree or yours; *everybody* messes
around in the docs tree.  People know to look closely at changes to
makefiles and such; nobody thinks to examine documentation changes for
such things. I think there are attackers out there who would like the
opportunity to run commands in the settings where kernels are built; we
need to think pretty hard before we make that easier to do.

See what I'm getting at here?

jon