Real utility of idmapd

[Guillaume Rousse]

Kevin Coffman wrote:
> On 3/22/07, Guillaume Rousse <Guillaume.Rousse at inria.fr> wrote:
>> Kevin Coffman wrote:
>> > On 3/22/07, Guillaume Rousse <Guillaume.Rousse at inria.fr> wrote:
>> >> J. Bruce Fields wrote:
>> >> >> >From the logs, the server seems to map ids on name, not names
>> on id:
>> >> >> Mar 20 15:33:52 stalingrad rpc.idmapd[19602]:  Server: (user) id
>> "501"
>> >> >> -> name "nobody"
>> >> >> Mar 20 15:33:52 stalingrad rpc.idmapd[19602]: nfsdcb:
>> >> >> authbuf=oberkampf.msr-inria.inria.fr authtype=group
>> >> >> Mar 20 15:33:52 stalingrad rpc.idmapd[19602]:  Server: (group) id
>> >> "501"
>> >> >> -> name "nogroup"
>> >> >>
>> >> >> So name-based mapping appears to be working upside down here...
>> >> >
>> >> > The above is expected.  For example, if the client is stat'ing a
>> file,
>> >> > then the server must translate the uid and gid stored in the file's
>> >> > inode into a string name that an NFSv4 client will understand.
>> >> It works on the client, indeed: files owned by uid 501 on the server
>> >> appears to be owned by user of the same name on the client, even if he
>> >> has a different uid there (500).
>> >>
>> >> My point it that on the server (stalingrad), file created from the
>> >> client use wrong uid (501), instead of being correctly mapped to
>> uid 500.
>> >
>> > You claim the file is created with the "wrong uid" on the server.
>> > Yet, an "ls -l" on that file on the server and on the client will
>> > result in the same name, right?
>> No. ls -l on the server attributes it to nobody, because uid 501 doesn't
>> exist there. It should have been 500 if the mapping succedeed.
> 
> Then I am confused on where the 501 came from.
client: user rousse, with uid 501
server: user rousse, with uid 500

server files belonging to user rousse on server appears to belong to
user rousse on client too: mapping works OK

client created files belonging to user rousse on client appears with uid
501 on server: mapping doesn't work, and my log expcert doesn't show any
attempt to map recevied name 'rousse' on uid, but a received uid '501'
to 'nobody' user.