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    SubjectRe: [netfilter-core] kernel panic: Out of memory and no killable processes... (2)
    Kirill A. Shutemov <kirill@shutemov.name> wrote:
    > On Mon, Jan 29, 2018 at 05:57:22PM +0100, Florian Westphal wrote:
    > > Kirill A. Shutemov <kirill@shutemov.name> wrote:
    > > > On Mon, Jan 29, 2018 at 08:23:57AM +0100, Florian Westphal wrote:
    > > > > > vmalloc() once became killable by commit 5d17a73a2ebeb8d1 ("vmalloc: back
    > > > > > off when the current task is killed") but then became unkillable by commit
    > > > > > b8c8a338f75e052d ("Revert "vmalloc: back off when the current task is
    > > > > > killed""). Therefore, we can't handle this problem from MM side.
    > > > > > Please consider adding some limit from networking side.
    > > > >
    > > > > I don't know what "some limit" would be. I would prefer if there was
    > > > > a way to supress OOM Killer in first place so we can just -ENOMEM user.
    > > >
    > > > Just supressing OOM kill is a bad idea. We still leave a way to allocate
    > > > arbitrary large buffer in kernel.
    > >
    > > Isn't that what we do everywhere in network stack?
    > >
    > > I think we should try to allocate whatever amount of memory is needed
    > > for the given xtables ruleset, given that is what admin requested us to do.
    >
    > Is it correct that "admin" in this case is root in random container?

    Yes.

    > I mean, can we get access to it with CLONE_NEWUSER|CLONE_NEWNET?

    Yes.

    > This can be fun.

    Do we prevent "admin in random container" to insert 2m ipv6 routes
    (alternatively: ipsec tunnels, interfaces etc etc)?

    > > I also would not know what limit is sane -- I've seen setups with as much
    > > as 100k iptables rules, and that was 5 years ago.
    > >
    > > And even if we add a "Xk rules" limit, it might be too much for
    > > low-memory systems, or not enough for whatever other use case there
    > > might be.
    >
    > I hate what I'm saying, but I guess we need some tunable here.
    > Not sure what exactly.

    Would memcg help?

    (I don't buy the "run untrusted binaries on linux is safe" thing, so
    I would not know).

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