[systemd-devel] Environment-variable security?

[David Parsley]

I already scrub the environment when executing external scripts, and I've
found that even after os.Unsetenv(...) the full environment is available to
all processes owned by the robot in /proc/<pid>/environ. I'm fleshing out a
solution where the process consumes the environment then scrubs it from
proc w/ execve before starting the main loop that can run external scripts.

I don't know what mechanism made the environment available via API, so I
wasn't sure if using an EnvironmentFile protected against that same
mechanism. If effective, that would be a nice solution that parallels
operation of the dockerized version.

So, anybody know what API calls an unprivileged user can make to get that
information from the unit file? It'd be nice to test before and after to
make sure the measure is effective.

Regards,
-David

On Mon, Nov 12, 2018 at 4:23 PM aleivag <aleivag at gmail.com> wrote:

> hi Reindl: I was protecting against "systemctl cat/show" disclosure of
> information, as stated in the question; but i agree with you, and there are
> always risk in passing credential in env variables, but you can always try
> to mitigate them (e.g. the main process can read the variables and then
> remove them from the env).
>
> El 12 nov. 2018 5:54 p. m., "Reindl Harald" <h.reindl at thelounge.net>
> escribió:
>
>
>
> Am 12.11.18 um 21:41 schrieb aleivag:
>
> > You can define those secrets on /etc/robotsecret.txt, and then on your
> > unit you do `EnvironmentFile=/etc/robotsecret.txt`
> >
> > then you protect /etc/robotsecret.txt as you would normally do
>
> and how does that protect anything?
>
> on a webserver running php it's just a one-liner to get $_ENV which is
> why sensitive data don't belong there and should never exposed that way
> like passwords in teh commandline are plain wrong
>
>
> > On Mon, Nov 12, 2018 at 4:49 PM David Parsley <parsley at linuxjedi.org
> > <mailto:parsley at linuxjedi.org>> wrote:
> >
> >     It's a fairly common practice to configure services and provide
> >     secrets with environment variables. For instance, both Hubot (made
> >     by Github) and Gopherbot (made by me) can get their Slack token from
> >     an environment variable. In my case,
> >     github.com/lnxjedi/ansible-role-gopherbot
> >     <http://github.com/lnxjedi/ansible-role-gopherbot> stores the Slack
>
> >     bot token with "Environtment=GOPHER_SLACK_TOKEN=xxx" in the systemd
> >     unit file. I had hoped to keep this info to the robot user by
> >     marking the unit file world-inaccessible. I was dismayed to see the
> >     log warning about values being accessible via the API, though super
> >     glad that my unprivileged user couldn't fetch it with a
> >     simple |systemctl cat gopherbot|. I know very little about DBUS or
>
> >     any APIs for systemd, so wanted to ask - is there some means by
> >     which a non-privileged user can access the values provided with
> >     "Environment=..." lines? Can I disable this by disabling dbus-daemon
> >     on server systems?
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