[gpfsug-discuss] [NFS-Ganesha-Support] does ganesha deny access for unknown UIDs?

[Billich Heinrich Rainer (PSI)]

Hello Daniel,

thank you. The clients do NFS v3 mounts, hence idmap is no option - as I know it's used in NFS v4 to map between uid/guid and names only? For a process to switch to a certain uid/guid in general one does not need a  matching passwd entry? I see that with ACLs you get issues as they use names, and you can't do a server-side group membership lookup, and there may be more subtle issues.

Anyway, I'll create the needed accounts on the server. By the way: We had the same issue with Netapp filers and it took a while to  find the configuration option to allow 'unknown' uid/gid  to access a nfs v3 export.

I'll try  to reproduce on a test system with increased logging to see what exactly goes wrong and maybe ask later to add a configuration option to ganesha to switch to a behaviour more similar to kernel-nfs.

Many client systems at my site are legacy and run various operating systems, hence a complete switch to NFS v4 is unlikely to happen soon.

cheers,

Heiner 
--
Paul Scherrer Institut
Heiner Billich                           
System Engineer Scientific Computing
Science IT / High Performance Computing                 
WHGA/106                              
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5232 Villigen PSI
Switzerland
 
Phone +41 56 310 36 02
heiner.billich at psi.ch 
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On 24/01/19 16:35, "Daniel Gryniewicz" <dang at redhat.com> wrote:

    Hi.
    
    For local operating FSALs (like GPFS and VFS), the way Ganesha makes 
    sure that a UID/GID combo has the correct permissions for an operation 
    is to set the UID/GID of the thread to the one in the operation, then 
    perform the actual operation.  This way, the kernel and the underlying 
    filesystem perform atomic permission checking on the op.  This 
    setuid/setgid will fail, of course, if the local system doesn't have 
    that UID/GID to set to.
    
    The solution for this is to use NFS idmap to map the remote ID to a 
    local one. This includes the ability to map unknown IDs to some local ID.
    
    Daniel
    
    On 1/24/19 9:29 AM, Billich Heinrich Rainer (PSI) wrote:
    > Hello,
    > 
    > a local account on a nfs client couldn’t write to a ganesha nfs export 
    > even with directory permissions 777. The solution was to create the 
    > account on the ganesha servers, too.
    > 
    > Please can you confirm that this is the intended behaviour? is there an 
    > option to change this and to map unknown accounts to nobody instead? We 
    > often have embedded Linux appliances or similar as nfs clients which 
    > need to place some data on the nfs exports  using uid/gid of local accounts.
    > 
    > We manage gids on the server side and allow NFS v3 client access only.
    > 
    > I crosspost this to ganesha support and to the gpfsug mailing list.
    > 
    > Thank you,
    > 
    > Heiner Billich
    > 
    > ganesha version: 2.5.3-ibm028.00.el7.x86_64