Messages in this thread | | | Date | Sun, 27 Dec 2009 11:36:10 -0500 | From | Michael Stone <> | Subject | Re: RFC: disablenetwork facility. (v4) |
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Serge Hallyn writes: > Michael Stone writes: >> The first reason why I'm not too worried is that anyone in a position to use >> disablenetwork for nefarious purposes is also probably able to use ptrace(), >> kill(), and/or LD_PRELOAD to similar ends. > > How do you mean?
I meant that, with the current interface, to set disablenetwork for pid P, you have either be pid P or to have been one of P's ancestors. In either case, you have lots of opportunity to mess with P's environment.
> I thought that disabling network was a completely > unprivileged operation? And subsequently executing a setuid-root > application won't reset the flag.
Correct and correct for the current patches.
>> The second reason why I'm not too worried is that I believe it to be >> straightforward to use the pre-existing MAC frameworks to prevent individually >> important processes from dropping networking privileges. >> >> Do you have a specific concern in mind not addressed by either of these >> observations? > > Near as I can tell the worst one could do would be to prevent remote > admins from getting useful audit messages, which could give you unlimited > time to keep re-trying the server, on your quest to a brute-force attack > of some sort, i.e. restarting the server with random passwords, and now > no audit msg about the wrong password gets generated, so you're free to > exhaust the space of valid passwords. > > Not saying I'm all that worried about it - just something that came to > mind.
I'll think about it further. Fortunately, there's no need to be hasty. :)
Michael
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