Re: Fwd: mount.nfs: access denied by server

["J. Bruce Fields" <bfields@fieldses.org>]

On Fri, Aug 21, 2009 at 02:16:08PM -0400, Chuck Lever wrote:
> I want to understand the server bug a little more.  I glanced over RFC  
> 2623 and didn't see anything specific.
>
> Is it the case that only Linux NFSD does this, or do other servers do  
> it?  In other words, is this a typical server response, and if so, is  
> there a specific semantic attached to it?
>
> If no list is provided, should the client assume that only AUTH_NONE and 
> AUTH_SYS are supported, or instead, perhaps that the client can try to 
> use any flavor?  In other words, if no list is provided, let the mount 
> proceed no matter what was specified by sec= ?

I think the safest behavior on the client would be something like:

	- If an explicit sec= is provided on the client, try that
	  flavor.  Otherwise:
		- If the server returned a nonempty list, pick something
		  off that list.  Otherwise:
		  	- Try auth_sys.

--b.

>
> Thanks for any clarification.
>
> Begin forwarded message:
>
>> From: Trond Myklebust <trond.myklebust@fys.uio.no>
>> Date: August 20, 2009 10:36:11 PM GMT-04:00
>> To: Wu Fengguang <fengguang.wu@intel.com>, "Mr. Charles Edward Lever" 
>> <Chuck.Lever@oracle.com>
>> Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>, LKML 
>> <linux-kernel@vger.kernel.org>
>> Subject: Re: mount.nfs: access denied by server
>>
>> On Fri, 2009-08-21 at 09:27 +0800, Wu Fengguang wrote:
>>> On Thu, Aug 20, 2009 at 09:02:29PM +0800, Trond Myklebust wrote:
>>>> On Thu, 2009-08-20 at 15:13 +0800, Wu Fengguang wrote:
>>>>> Hi,
>>>>>
>>>>> After upgrading NFS client kernel to latest linux-next, NFS mount
>>>>> failed:
>>>>>
>>>>>        # mount -t nfs pxe:/cc /cc
>>>>>        mount.nfs: access denied by server while mounting pxe:/cc
>>>>>
>>>>>        # uname -a
>>>>>        Linux hp 2.6.31-rc6-next-20090818 #61 SMP Thu Aug 20  
>>>>> 14:46:10 CST 2009 x86_64 GNU/Linux
>>>>>
>>>>> However server log says OK:
>>>>>
>>>>>        Aug 20 15:02:09 wu-t61 mountd[4599]: authenticated mount  
>>>>> request from 192.168.11.6:973 for /cc (/cc)
>>>>>        Aug 20 15:02:09 wu-t61 mountd[4599]: authenticated unmount 
>>>>> request from 192.168.11.6:974 for /cc (/cc)
>>>>>
>>>>> However-2: nfsroot can be mounted at boot time. Server kernel has 
>>>>> always been 2.6.30.
>>>>>
>>>>> Any ideas?
>>>>>
>>>>> Thanks,
>>>>> Fengguang
>>>>
>>>> Can you try again after enabling mount debugging on the NFS client?
>>>>
>>>> echo 512 > /proc/sys/sunrpc/nfs_debug
>>>
>>> I used 1024 and found the mount failed here in nfs_walk_authlist():
>>>
>>>        dfprintk(MOUNT, "NFS: server does not support requested auth  
>>> flavor\ n");
>>>        nfs_umount(request);
>>
>> Thanks Fengguang!
>>
>> Chuck, this looks like one of yours. Could it be that you are hitting
>> the same Linux knfsd bug that Tom Haynes saw with a Solaris client?
>> AFAICR, the problem was that existing nfs servers do not set a default
>> auth flavour, and so you just have to try with auth_sys and see if it
>> succeeds...
>>
>> Cheers
>>  Trond
>>
>
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com
>
>
>