netdev - Re: [BUG] Potential net namespace information leakage in /proc/net/sockstat

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Date:   Fri, 3 Jun 2022 16:14:51 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "Liu, Congyu" <liu3101@...due.edu>
Cc:     "ebiederm@...ssion.com" <ebiederm@...ssion.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [BUG] Potential net namespace information leakage in /proc/net/sockstat

On Fri, Jun 3, 2022 at 3:53 PM Liu, Congyu <liu3101@...due.edu> wrote:
>
> Hi,
>
> In our test conducted on namespace, we found net information leakage in /proc/net/sockstat. For instance, the TCP "alloc" field exposes a TCP socket related counter that is shared across all net namespaces on the same host. Is this an intentional design for specific purposes?
>

These counters are global to the host, not per netns.
Note that /proc/slabinfo can somewhat 'reveal' similar information.

I guess nobody cared enough yet.

Something more concerning is the fact that one netns can steal all
tcp_mem memory.