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Message-ID: <f4e2cf9a-04e4-47a8-88f5-70544b516d3e@redhat.com>
Date: Thu, 9 May 2024 10:56:16 -0400
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Subject: Re: [PATCH] mount: If a reserved ports is used, do so for the pings
 as well
To: Trond Myklebust <trondmy@hammerspace.com>,
 "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
 "alex@caoua.org" <alex@caoua.org>
References: <ZhkMcZDhJhsVjo52@vm1.arverb.com>
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 <ae1d55fc8e6951832548323228fc2b9a0eb5dfe4.camel@hammerspace.com>
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From: Steve Dickson <steved@redhat.com>
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On 4/21/24 6:14 PM, Trond Myklebust wrote:
> On Sun, 2024-04-21 at 17:38 -0400, Steve Dickson wrote:
>>
>>
>> On 4/21/24 12:06 PM, Trond Myklebust wrote:
>>> On Sun, 2024-04-21 at 07:09 -0400, Steve Dickson wrote:
>>>>
>>>>
>>>> On 4/12/24 6:26 AM, Alexandre Ratchov wrote:
>>>>> Hi,
>>>>>
>>>>> mount.nfs always uses a high port to probe the server's ports
>>>>> (regardless of
>>>>> the "-o resvport" option).  Certain NFS servers (ex.  OpenBSD -
>>>>> current) will
>>>>> drop the connection, the probe will fail, and mount.nfs will
>>>>> exit
>>>>> before any
>>>>> attempt to mount the file-system.  If mount.nfs doesn't ping
>>>>> the
>>>>> server from
>>>>> a high port, mounting the file system will just work.
>>>>>
>>>>> Note that the same will happen if the server is behind a
>>>>> firewall
>>>>> that
>>>>> blocks connections to the NFS service that originates from a
>>>>> high
>>>>> port.
>>>> Committed... (tag: nfs-utils-2-7-1-rc7)
>>>>
>>>> I just hope we don't run out of privilege ports during
>>>> a mount storm (aka when a server reboots).
>>>
>>> Agreed, and that is why this change was entirely the wrong thing to
>>> do.
>> Well the patch was sitting around for a while without any objection
>> so I figured I would go with it since it would make mounts
>> work on other OSs
>>
>>>
>>> The point of the ping is to allow for fast failover in the case
>>> where
>>> the portmap/rpcbind server returns incorrect or stale information.
>>>
>>> If there are servers out there that deliberately break the
>>> convention
>>> for NULL ping, as described in RFC5531, then we might allow
>>> optional
>>> use of the privileged port for those servers, but please don't
>>> force
>>> this on everyone else.
>> The patch is on the top of stack... easy revert-able... Is that what
>> you are suggesting?
> 
> That is my suggestion for now, yes.
> 
> I don't have any objection to a patch that adds opt-in functionality
> either to turn off the NULL ping, or to force that ping to use a
> privileged port. However we should not change the default behaviour to
> cause the existing paucity of privileged ports to be even more of a
> problem.
> 

Reverted.

steved.