permission denied.

permission denied.

[Rongqing "Frank" Tu]

Hi All,
I am running on Linux 2.4.18-3 and try to setup a "link" nfs, but got a 
"permission denied".

a link nfs is like this:
in machine 1:  export A
in machine 2:  mount A to B and then export B
in mahcine 3:  mount B to C.

the "permission denied" occurs at the last step when I tried to mount B to 
C.

I am working on a software which needs this kind of structure, so I wonder 
if NFS support such "link" exporting and mounting?

Thanks.

Frank Tu



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Re: permission denied.

[Neil Brown]

On Thursday November 21, rtu@packetgeneral.com wrote:
> Hi All,
> I am running on Linux 2.4.18-3 and try to setup a "link" nfs, but got a 
> "permission denied".
> 
> a link nfs is like this:
> in machine 1:  export A
> in machine 2:  mount A to B and then export B
> in mahcine 3:  mount B to C.
> 
> the "permission denied" occurs at the last step when I tried to mount B to 
> C.
> 
> I am working on a software which needs this kind of structure, so I wonder 
> if NFS support such "link" exporting and mounting?

re-exporting NFS filesystems is not supported and it is unlikely that
it will be.  Partly there are protocol issues that make it an
unsolvable problem in general (though many specific cases can probably
be made to work).  Partly there is usually a better solution to the
underlying problem.

One thing you could try if you were really set on this path is to use
the user-space nfs server aka "Universal NFS daemon" aka unfsd.  This
can export any filesystem, but has speed and some reliability issues.

NeilBrown


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Re: permission denied.

[Rongqing "Frank" Tu]

Dear Neil,
Thank you for your help. 
I don't think Universal NFS is suitable for my situation. 

My situation is there is a linux box sitting between NFS server and end 
users. This linux box will transfer the NFS server to the end user, so in 
this linux box, I need to mount the NFS server, then export mounted point 
to the end users.

		    NFS			NFS
	NFS_server ------> Linux_Box --------> end users

In the linux box, there are two commands:
	mount -t nfs NFS_server:/path/dir   /linux_box_path/dir
	exportfs -ra 
	(in /etc/exports: /linux_box_path/dir *(rw) )

In the normal situation, such "link" exporting and mounting is not 
necessary since the end user can directly mount the NFS server to itself, 
but I need to add some functions in my Linux_Box and this becomes 
necessary.

Are you very sure NFS protocol doesn't support such "link" exporting and 
mounting?

Thanks.

Frank

 On Fri, 22 Nov 2002, Neil Brown 
wrote:

> On Thursday November 21, rtu@packetgeneral.com wrote:
> > Hi All,
> > I am running on Linux 2.4.18-3 and try to setup a "link" nfs, but got a 
> > "permission denied".
> > 
> > a link nfs is like this:
> > in machine 1:  export A
> > in machine 2:  mount A to B and then export B
> > in mahcine 3:  mount B to C.
> > 
> > the "permission denied" occurs at the last step when I tried to mount B to 
> > C.
> > 
> > I am working on a software which needs this kind of structure, so I wonder 
> > if NFS support such "link" exporting and mounting?
> 
> re-exporting NFS filesystems is not supported and it is unlikely that
> it will be.  Partly there are protocol issues that make it an
> unsolvable problem in general (though many specific cases can probably
> be made to work).  Partly there is usually a better solution to the
> underlying problem.
> 
> One thing you could try if you were really set on this path is to use
> the user-space nfs server aka "Universal NFS daemon" aka unfsd.  This
> can export any filesystem, but has speed and some reliability issues.
> 
> NeilBrown
> 



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Re: permission denied.

[Bernd Schubert]

On Friday 22 November 2002 17:11, Rongqing \"Frank\" Tu wrote:
> Dear Neil,
> Thank you for your help.
> I don't think Universal NFS is suitable for my situation.
>

Hi Frank,

Using any other user-space export daemon should also do what you want. So you 
could try to use samba for example.

Bernd


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Re: permission denied.

[Rongqing "Frank" Tu]

Thanks.
I found the place to resolve the problem.
in the kernel code of nfsd, exp_export() in export.c, ignore the check of 
fs flag of FS_REQUIRES_DEV.
inode->i_sb->s_type->fs_flags.

Frank
On Sat, 23 Nov 2002, Bernd Schubert wrote:

> On Friday 22 November 2002 17:11, Rongqing \"Frank\" Tu wrote:
> > Dear Neil,
> > Thank you for your help.
> > I don't think Universal NFS is suitable for my situation.
> >
> 
> Hi Frank,
> 
> Using any other user-space export daemon should also do what you want. So you 
> could try to use samba for example.
> 
> Bernd
> 



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Permission denied

[Jeremy Sanders]

I've seen this problem a couple of times (I think I reported it to the
list before but I can find the posting). Using the automounter to mount
home directories (rw,v3,rsize=8192,wsize=8192,hard,intr,udp,lock), it
seems that rebooting a Linux server can give a "Permission denied" on
the client. Further attempts at accessing the mountpoint give this error.
It can be fixed my umounting it (if nothing is using it), and reaccessing
the mountpoint.

The server is running RedHat's 2.4.18-27.7.x kernel, and the client is
using 2.4.18-17.7.x (unfortunately).

dmesg on the client shows:

nfs: server server.ast.cam.ac.uk not responding, still trying
nfs: task 57889 can't get a request slot
nfs: server server.ast.cam.ac.uk OK
nfs: server server.ast.cam.ac.uk OK

sendmail gave errors such as:

May  7 16:07:39 xserv1 sendmail[22255]: h47EwYl22254: forward
/home/gmorris: transient error: Timeout on file open
May  7 16:07:39 xserv1 sendmail[22195]: h47Eljl22194: forward
/home/gmorris: transient error: Timeout on file open
May  7 16:07:39 xserv1 sendmail[22255]: h47EwYl22254: forward
/home/gmorris/.forward: Permission denied
May  7 16:07:39 xserv1 sendmail[22195]: h47Eljl22194: forward
/home/gmorris/.forward: Permission denied

Any ideas? I suppose it's hard to diagnose this without a network traffic
analysis, and we're not using the standard kernel either. I suppose it
could be an automounter bug.


Jeremy

-- 
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X-Ray Group, Institute of Astronomy, University of Cambridge, UK.
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Re: Permission denied

[James Pearson]

What version of nfs-utils are you running on the server?

I had a problem if the server crashed before a client mount could be
recorded to /var/lib/nfs/rmtab, the client got permission denied on the
mount point after the server rebooted - see:

http://marc.theaimsgroup.com/?l=linux-nfs&m=101828003630443&w=2

This is fixed in the more recent versions of nfs-utils.

Also, if you manually attempt to umount an NFS file system (automounted
or not), but the umount fails because the file system is busy - this
will cause a problem as rpc.mountd on the server has already removed the
client from /var/lib/nfs/rmtab - which means if the server reboots, the
server has no record of the client mount, so you get permission denied
on client when it accesses the mount point ... see:

http://marc.theaimsgroup.com/?l=linux-nfs&m=104558814532107&w=2

I had this problem - my work round is not to manually umount automounted
file systems ... (or, if I have to, use a hacked version of umount that
doesn't contact rpc.mountd on the server).

James Pearson

Jeremy Sanders wrote:
> 
> I've seen this problem a couple of times (I think I reported it to the
> list before but I can find the posting). Using the automounter to mount
> home directories (rw,v3,rsize=8192,wsize=8192,hard,intr,udp,lock), it
> seems that rebooting a Linux server can give a "Permission denied" on
> the client. Further attempts at accessing the mountpoint give this error.
> It can be fixed my umounting it (if nothing is using it), and reaccessing
> the mountpoint.
> 
> The server is running RedHat's 2.4.18-27.7.x kernel, and the client is
> using 2.4.18-17.7.x (unfortunately).
> 
> dmesg on the client shows:
> 
> nfs: server server.ast.cam.ac.uk not responding, still trying
> nfs: task 57889 can't get a request slot
> nfs: server server.ast.cam.ac.uk OK
> nfs: server server.ast.cam.ac.uk OK
> 
> sendmail gave errors such as:
> 
> May  7 16:07:39 xserv1 sendmail[22255]: h47EwYl22254: forward
> /home/gmorris: transient error: Timeout on file open
> May  7 16:07:39 xserv1 sendmail[22195]: h47Eljl22194: forward
> /home/gmorris: transient error: Timeout on file open
> May  7 16:07:39 xserv1 sendmail[22255]: h47EwYl22254: forward
> /home/gmorris/.forward: Permission denied
> May  7 16:07:39 xserv1 sendmail[22195]: h47Eljl22194: forward
> /home/gmorris/.forward: Permission denied
> 
> Any ideas? I suppose it's hard to diagnose this without a network traffic
> analysis, and we're not using the standard kernel either. I suppose it
> could be an automounter bug.
> 
> Jeremy
> 
> --
> Jeremy Sanders <jss@ast.cam.ac.uk>   http://www-xray.ast.cam.ac.uk/~jss/
> X-Ray Group, Institute of Astronomy, University of Cambridge, UK.
> Public Key Server PGP Key ID: E1AAE053
> 
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Re: Permission denied

[Trond Myklebust]

>>>>> " " == Jeremy Sanders <jss@ast.cam.ac.uk> writes:

     > I've seen this problem a couple of times (I think I reported it
     > to the list before but I can find the posting). Using the
     > automounter to mount home directories
     > (rw,v3,rsize=8192,wsize=8192,hard,intr,udp,lock), it seems that
     > rebooting a Linux server can give a "Permission denied" on the
     > client.

Can it be duplicated on newer kernels?

Which automounter BTW?

Cheers,
  Trond


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Re: Permission denied

[Jeremy Sanders]

On Wed, 7 May 2003, James Pearson wrote:

> What version of nfs-utils are you running on the server?

nfs-utils-0.3.3 on both. From the thread this looks like it has the bug
(unless RedHat patched it in their rpm).  I'll have a go updating it and
see whether we still get the bug.

> Also, if you manually attempt to umount an NFS file system (automounted
> or not), but the umount fails because the file system is busy - this
> will cause a problem as rpc.mountd on the server has already removed the
> client from /var/lib/nfs/rmtab - which means if the server reboots, the
> server has no record of the client mount, so you get permission denied
> on client when it accesses the mount point ... see:

That's interesting. Thanks!

Jeremy

-- 
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X-Ray Group, Institute of Astronomy, University of Cambridge, UK.
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Re: Permission denied

[Jeremy Sanders]

On Wed, 7 May 2003, Trond Myklebust wrote:

> Can it be duplicated on newer kernels?

I'm not sure. I couldn't reproduce the problem when rebooting machines by
hand, and I don't think I can do much testing with the production
machines as I can't easily upgrade the kernel. I'll invesitgate this.

> Which automounter BTW?

autofs-3.1.7

Thanks, Jeremy

-- 
Jeremy Sanders <jss@ast.cam.ac.uk>   http://www-xray.ast.cam.ac.uk/~jss/
X-Ray Group, Institute of Astronomy, University of Cambridge, UK.
Public Key Server PGP Key ID: E1AAE053


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Permission denied

[Daniel Bramkamp]

Hi list,

I am experiencing some issues with a NFS server running on Linux Kernel 
2.4.26 with nfs-utils-1.0.6 installed. Basically it works great, 
however, sometimes access to files and directories stored on the server 
is denied for a certain user account. I am not sure if it affects other 
users as well - only heard complaints from that particular user so far. 
This happens very infrequently. They mainly use KDE's Konqueror to 
access the NFS shares but the problem affects Gnome's Nautilus and the 
KDE konsole as well. Any ideas what could cause this weird behaviour ?

TIA
-- 
Daniel Bramkamp


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RE: Permission denied

[Tradebit Service]

 
> great, however, sometimes access to files and directories 
> stored on the server is denied for a certain user account. I 
> am not sure if it affects other users as well - only heard 
> complaints from that particular user so far. 

daniel,

just a wild guess: did you compare the user IDs in /etc/shadow
on both systems?

if you do a "ls -l" on the files on the client, who is the owner
and what are the access flags?

eg:

-rw-rw-r--    1 ftp      users       28076 Dec 19 18:59 somefile.tgz

that would mean, that only the user "ftp" and the members of the
group "users" could write (and delete) the file.

compare these flags and ownerships on both systems.

Cheers!

--
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http://www.tradebit.com/



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RE: Permission denied

[Daniel Bramkamp]

Quoting Tradebit Service <info@tradebit.com>:

>
>> great, however, sometimes access to files and directories
>> stored on the server is denied for a certain user account. I
>> am not sure if it affects other users as well - only heard
>> complaints from that particular user so far.
>
> daniel,

Hi Ralf,

thanks for your reply.

> just a wild guess: did you compare the user IDs in /etc/shadow
> on both systems?

sorry, I should have added this to my orginal post. The user accounts 
are managed via LDAP. UIDs start at 10000 and they do not overlap with 
system accounts. Also, when the problem arises, access to all NFS 
shares is denied, not just a single directory or file.

-- 
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Re: Permission denied

[Daniel Bramkamp]

Quoting Frank van Maarseveen <frankvm@frankvm.com>:

> On Tue, Feb 07, 2006 at 12:34:48PM +0100, Daniel Bramkamp wrote:
>> Hi list,
>>
>> I am experiencing some issues with a NFS server running on Linux Kernel
>> 2.4.26 with nfs-utils-1.0.6 installed. Basically it works great,
>> however, sometimes access to files and directories stored on the server
>> is denied for a certain user account. I am not sure if it affects other
>> users as well - only heard complaints from that particular user so far.
>
> A bit late but.. is that user a member of more than 16 groups?

Hi,

yesterday I reinstalled the server. The server is now running Gentoo 
instead of Slackware. The installed software is up to date now. Kernel 
is 2.6.14, nfs-utils is still 1.0.6, it seems 1.0.8 is currently a 
realease candidate. Half an hour ago I got a call from the user - the 
problem still exists. The user is a member of 13 groups. I really hoped 
the update would solve the problem since I have no idea how to fix this.

-- 
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Re: Permission denied

[Trond Myklebust]

On Mon, 2006-02-20 at 13:16 +0100, Daniel Bramkamp wrote:
> Quoting Frank van Maarseveen <frankvm@frankvm.com>:
> 
> > On Tue, Feb 07, 2006 at 12:34:48PM +0100, Daniel Bramkamp wrote:
> >> Hi list,
> >>
> >> I am experiencing some issues with a NFS server running on Linux Kernel
> >> 2.4.26 with nfs-utils-1.0.6 installed. Basically it works great,
> >> however, sometimes access to files and directories stored on the server
> >> is denied for a certain user account. I am not sure if it affects other
> >> users as well - only heard complaints from that particular user so far.
> >
> > A bit late but.. is that user a member of more than 16 groups?
> 
> Hi,
> 
> yesterday I reinstalled the server. The server is now running Gentoo 
> instead of Slackware. The installed software is up to date now. Kernel 
> is 2.6.14, nfs-utils is still 1.0.6, it seems 1.0.8 is currently a 
> realease candidate. Half an hour ago I got a call from the user - the 
> problem still exists. The user is a member of 13 groups. I really hoped 
> the update would solve the problem since I have no idea how to fix this.

You have to look at the client machine too.

Is the user still limited to 13 groups on the client, and do the
numerical uid/gid values match on the client and server?

Cheers,
  Trond



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Re: Permission denied

[Daniel Bramkamp]

Quoting Trond Myklebust <trond.myklebust@fys.uio.no>:


> You have to look at the client machine too.

yeah, the client in this case is a terminal server.

> Is the user still limited to 13 groups on the client, and do the
> numerical uid/gid values match on the client and server?

Since I use LDAP to store user accounts the uid and gid is the same on 
all servers. The user is not a member of any local group on any server 
either so the total number of groups the particular user is in is 13 on 
all servers. I just double checked that.

-- 
Daniel Bramkamp

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