On Fri, Mar 11, 2016 at 04:34:06PM +0100, Florian Westphal wrote: > Yuriy M. Kaminskiy <yumkam@xxxxxxxxx> wrote: > > BTW, all those hash/conntrack/etc default sizes was calculated from > > physical memory size in assumption there will be only *one* instance of > > those tables. Obviously, introduction of network namespaces (and > > especially unprivileged user-ns) thrown this assumption in the window > > (and here comes that "falling back to vmalloc" message again; in pre-netns > > world, those tables were allocated *once* on early system startup, with > > typically plenty of free and unfragmented memory). > > No idea how to fix this expect by removing conntrack support in net > namespaces completely. > > I'd disallow all write accesses to skb->nfct (NAT, CONNMARK, > CONNSECMARK, ...) and then no longer clear skb->nfct when forwarding > packet from init_ns to container. > > Containers could then still test conntrack as seen from init namespace pov > in PREROUTING/FORWARD/INPUT (but not OUTPUT, obviously). > > [ OUTPUT *might* be doable as well by allowing NEW creation in output > but skipping nat and deferring the confirmation/commit of the new > entry to the table until skb leaves initns ] > > We could key conntrack entries to initns conntrack table > instead of adding one new table per netns, but seems like this only > replaces one problem with a new one (filling/blocking initns table from > another netns). We can add a global perns limit in terms of conntrack entries that can only be set via CAP_NET_ADMIN from the initns. Thus, we avoid the filling/blocking from another netns, or hide this knob to unpriviledged userns somehow. In the previous netfilter workshop I remember we agreed on going towards having a single conntrack table for netns, so I suggest we follow that direction. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
