Re: [PATCH RFC/RFT net-next 00/17] net: Convert neighbor tables to per-namespace

[David Ahern]

On 7/17/18 11:40 AM, Cong Wang wrote:
> On Tue, Jul 17, 2018 at 5:11 AM <dsahern@xxxxxxxxxx> wrote:
>>
>> From: David Ahern <dsahern@xxxxxxxxx>
>>
>> Nikita Leshenko reported that neighbor entries in one namespace can
>> evict neighbor entries in another. The problem is that the neighbor
>> tables have entries across all namespaces without separate accounting
>> and with global limits on when to scan for entries to evict.
> 
> It is nothing new, people including me already noticed this before.
> 
> 
>>
>> Resolve by making the neighbor tables for ipv4, ipv6 and decnet per
>> namespace and making the accounting and threshold limits per namespace.
> 
> 
> The last discussion about this a long time ago concluded that neigh
> table entries are controllable by remote, so after moving it to per netns,
> it would be easier to DOS the host.
> 

There are still limits on the total number of entries and with
per-namespace limits an admin has better control.