[rhelv6-list] NFS ID map?

[Joshua Baker-LePain]

On Tue, 22 Oct 2013 at 12:19pm, Chris Adams wrote

> Once upon a time, Chris Adams <linux at cmadams.net> said:
>> Oh, I figured out my problem - this temporary/migration export is on a
>> different subnet, and my fsid=0 export was was only for the new subnet.
>> D'oh!  Fixed that, and NFSv4, and ID mapping (with the default config),
>> are now working.  Now, on with the (migration) show!
>
> Well, I thought ID mapping was working.  "ls" shows the right user, but
> I can't actually access directories as that user on the NFS client:
>
> $ id
> uid=500(vmail) gid=500(vmail) groups=500(vmail)
> $ ls -ld tmp
> drwx------ 2 vmail vmail 4096 Oct 22 14:09 tmp
> $ ls -l tmp
> ls: tmp: Permission denied
>
> The vmail user/group is 1000 on the NFS server.  Why would the
> translation work for stat() calls from ls, but not when I try to
> actually access the files?

Are you using Kerberos with NFSv4?  If not, then the numeric UIDs and GIDs 
still must match.  idmapd *will* map usernames for display purposes (i.e. 
what 'ls -l' sees), but the numeric IDs are still used for permissions. 
Clear as mud, ain't it?

At least, that's my experience of it...

-- 
Joshua Baker-LePain
QB3 Shared Cluster Sysadmin
UCSF