I Guess I Don't Understand NFS As Well As I Thought

[Doug Hardie]

On 24 November 2012, at 14:37, Tim Daneliuk wrote:

> On 11/24/2012 03:25 PM, Doug Hardie wrote:
>> 
>> On 24 November 2012, at 12:32, Tim Daneliuk wrote:
>> 
>>> Can someone kindly explain what is going on here:
>>> 
>>> Machine A:  FreeBSD - was running 8, just upgraded to 9.1-PRE
>>>            (I don't recall seeing the behavior described below
>>>             in V8, but then, I don't think I ever tried it).
>>> 
>>> Machine B:  Linux Mint Desktop
>>> 
>>> - Machine A acts as an NFS server for Machine B.
>>> 
>>> - Machine A exports a particular directory like this:
>>> 
>>>   /usr/foo  -maproot=myid     -network ...
>>> 
>>> 
>>> - /usr/foo/bar is owned by root on Machine A and has files therein
>>>  owned as root:root with permissions of 600.
>>> 
>>> - If I access /usr/foo/bar/file1 from Machine B, I cannot read it
>>>  but - and this is the part I don't get - I CAN *rename* it.
>>> 
>>> What's going on?  Since /foo/bar/ is owned by root and everything
>>> in it is 600 root:root, I would not expect a remote access to allow
>>> things like renaming.  Clearly I am missing something here, but I
>>> don't get it.
>> 
>> What are the permissions on the directory /usr/foo/bar?
> 
> 775
> 
> 
> Let me correct something.  The files in that directory are
> owned by root:wheel (not root:root - I got my *nixes
> confused), but they definitely have 600 perms.
> 
> On Machine A, user 'myid' is IN the wheel group but I still
> don't see how he's getting permission to rename the file.\

Renaming a file does not change the file itself.  It updates the directory.  Any user in group wheel has the authority to write to the directory (e.g., change a file's name).  The directory permissions are rwx for group wheel.  You can either try a user on machine B who is not in group wheel or change the directory permissions to 755 on /usr/foo/bar.  Then it would work as you expect.