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Re: [PATCH 01/11] rxrpc: Add a common object cache

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From: David Howells <dhowells@redhat.com>
Date: Tue, 08 Mar 2016 21:11:09 +0000

> I can put in a limit per peer, where a 'peer' is either a particular remote
> UDP port or particulat remote host.  TCP has this by virtue of having a
> limited number of ports available per IP address.  But if I have 10 IP
> addresses available, I can attempt to set up half a million TCP connections to
> a server simultaneously.  If I have access to a box that has an NFS mount on
> it, I can potentially open sufficient TCP ports that the NFS mount can't make
> a connection if it's not allowed to use privileged ports.

You must hold onto and commit locally to state for each and every one
of those remote TCP connections you create and actually move to
established state.

It's completely different, both sides have to make a non-trivial
resource commitment.

For this RXRPC stuff, you don't.

That's the important and critical difference.

My core argument still stands that RXRPC is fundamental DoS'able, in a
way that is not matched by TCP or our routing code or similar
subsystems.

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Thread

[PATCH 00/11] RxRPC: Rewrite part 2 David Howells <dhowells@redhat.com> - 2016-03-07 15:40 +0100
  [PATCH 11/11] rxrpc: Rename rxrpc_UDP_error_report() to  rxrpc_error_report() David Howells <dhowells@redhat.com> - 2016-03-07 15:40 +0100
  [PATCH 07/11] rxrpc: Rename ar-peer.c to peer-object.c David Howells <dhowells@redhat.com> - 2016-03-07 15:40 +0100
  [PATCH 05/11] rxrpc: procfs file to list local endpoints David Howells <dhowells@redhat.com> - 2016-03-07 15:40 +0100
  [PATCH 02/11] rxrpc: Do procfs lists through objcache David Howells <dhowells@redhat.com> - 2016-03-07 15:50 +0100
  [PATCH 09/11] rxrpc: Add /proc/net/rxrpc_peers to display the known  remote endpoints David Howells <dhowells@redhat.com> - 2016-03-07 15:50 +0100
  [PATCH 06/11] rxrpc: Rename ar-local.c to local-event.c David Howells <dhowells@redhat.com> - 2016-03-07 15:50 +0100
  [PATCH 10/11] rxrpc: Rename ar-error.c to peer-event.c David Howells <dhowells@redhat.com> - 2016-03-07 15:50 +0100
  [PATCH 01/11] rxrpc: Add a common object cache David Howells <dhowells@redhat.com> - 2016-03-07 15:50 +0100
    Re: [PATCH 01/11] rxrpc: Add a common object cache David Miller <davem@davemloft.net> - 2016-03-07 19:50 +0100
      Re: [PATCH 01/11] rxrpc: Add a common object cache David Howells <dhowells@redhat.com> - 2016-03-07 23:50 +0100
        Re: [PATCH 01/11] rxrpc: Add a common object cache David Miller <davem@davemloft.net> - 2016-03-08 05:10 +0100
          Re: [PATCH 01/11] rxrpc: Add a common object cache David Howells <dhowells@redhat.com> - 2016-03-08 12:50 +0100
            Re: [PATCH 01/11] rxrpc: Add a common object cache David Howells <dhowells@redhat.com> - 2016-03-08 14:10 +0100
              Re: [PATCH 01/11] rxrpc: Add a common object cache David Miller <davem@davemloft.net> - 2016-03-08 21:20 +0100
            Re: [PATCH 01/11] rxrpc: Add a common object cache David Miller <davem@davemloft.net> - 2016-03-08 21:20 +0100
              Re: [PATCH 01/11] rxrpc: Add a common object cache David Howells <dhowells@redhat.com> - 2016-03-08 22:20 +0100
                Re: [PATCH 01/11] rxrpc: Add a common object cache David Miller <davem@davemloft.net> - 2016-03-09 04:10 +0100
  [PATCH 04/11] rxrpc: Implement local endpoint cache David Howells <dhowells@redhat.com> - 2016-03-07 15:50 +0100
  [PATCH 03/11] rxrpc: Separate local endpoint object handling out  into its own file David Howells <dhowells@redhat.com> - 2016-03-07 15:50 +0100

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