Messages in this thread | | | From | Al Boldi <> | Subject | Re: [PATCH 1/1] threads_max: Simple lockout prevention patch | Date | Tue, 25 Apr 2006 13:44:58 +0300 |
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Nick Piggin wrote: > Al Boldi wrote: > > Nick Piggin wrote: > >>Al Boldi wrote: > >>>Could do that by: > >>> > >>> # echo 1 > /proc/sys/kernel/su-pid > >>> > >>>which would imply nr-threads = 1 > >>> > >>>So maybe introduce /proc/sys/kernel/nr-threads to allow that to be > >>>variable, but this isn't really critical. > >> > >>Why not just have su-nr-threads? > > > > Unless I am misunderstanding you, even root/root-proc can be hit by a > > runaway, so the threads-max limits this globally which is great, but > > this may lock-you out of being able to control the situation based on > > uid only. > > > > Thus this patch gives root the ability to allow a certain pid to exceed > > the threads-max limit, while all other pids are still limited. > > But the point is that root is able to get their pids under control, > and can't be DoSed by unpriv users. Right?
Or even by root.
> Nothing is going to be perfect, I mean the su-pid pid could get "hit > bya runaway" and is arguably worse than nr-threads-su, because it has > no upper limit and coult take down the whole system.
The su-pid is a temporary measure set by root after evaluating the current situation, and additionally limiting this by su-nr(pid)-threads may probably be a good idea. Maybe something like this:
if (nr_threads >= max_threads) if ((p->pid != su_pid) || (nr_threads >= (max_threads + su_pid_threads))) goto bad_fork_cleanup_count;
But I really don't think this is critical.
Thanks!
-- Al
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