On 02/22/2017 05:23 AM, Kees Bakker wrote:
On 21-02-17 19:49, Brendan Kearney wrote:
On 02/21/2017 10:57 AM, Kees Bakker wrote:
Hey,

Maybe one of the NFS users on this list could give me a hint what
could be wrong. I'm not sure if it has any relation with FreeIPA/Kerberos.

I've set up an NFS server and I can mount the NFS directory on my client. So, 
I'm
guessing that setting up Kerberos principal was done correctly.

However, only root can actually access the mounted contents. Any other user
only sees question marks as shown below.

The mount command is simple.
$ sudo mount -v -t nfs srv1.example.com:/home /nfshome
mount.nfs: timeout set for Tue Feb 21 16:36:39 2017
mount.nfs: trying text-based options 
'vers=4,addr=172.16.16.45,clientaddr=172.16.16.30'

On the server side /etc/exports looks like this.
/home        *(rw,sync,sec=krb5i,no_subtree_check)

$ sudo mount |grep nfs
srv1.example.com:/home on /nfshome type nfs4 
(rw,relatime,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=krb5i,clientaddr=172.16.16.30,local_lock=none,addr=172.16.16.45)

$ sudo ls -ld /nfshome
drwxr-xr-x 1 root root 72 feb 21 04:22 /nfshome
$ sudo ls -l /nfshome
total 0
drwxr-xr-x 1 keesb  keesb  116 jan 27 12:56 keesb

$ ls -l /nfshome
ls: cannot access '/nfshome': Permission denied
$ ls -l / | grep nfshome
ls: cannot access '/nfshome': Permission denied
d?????????   ? ?    ?       ?            ? nfshome

sec=krb* means that the user accessing the mount has to authenticate with a 
kerberos ticket, and has to be the user or in the group granted access to the 
share.  from the looks of things, the user did not authenticate, and that is 
why the permissions are question marks.  check the kerberos tickets that the 
user has (klist output).  Otherwise, the ownership might be user and group that 
the client machine does not recognize (think posix user/group that is not in 
sync between the NFS server and the client)
Thanks for the reply.

In this case the user _is_ authenticated.
keesb@client1:~$ klist
Ticket cache: KEYRING:persistent:60001:60001
Default principal: ke...@example.com

Valid starting     Expires            Service principal
22-02-17 09:20:30  23-02-17 09:20:25  krbtgt/example....@example.com
no, the user has a TGT. a nfs/host.domain.tld@REALM ticket is needed to authenticate.

What other grants could be needed? HBAC Rules?

Do I need an nfs principal for the client? (I didn't think so, but many HOWTO's 
say so [2]. Anyway, it
doesn't help to get access for the user.)
there are principals to create and keytabs to be updated on hte NFS sever, if not done already. then the user should be able to pull the ticket for auth.

Furthermore, I'm guessing that the host principle which I got after 
ipa-client-install is
good enough. (This [1] wiki suggests that I need to do a ipa-getkeytab for it, 
which I
did not do.)
# klist -ke
Keytab name: FILE:/etc/krb5.keytab
KVNO Principal
---- --------------------------------------------------------------------------
    1 host/client1.example....@example.com (aes256-cts-hmac-sha1-96)
    1 host/client1.example....@example.com (aes128-cts-hmac-sha1-96)

[1] http://wiki.linux-nfs.org/wiki/index.php/NFS_and_FreeIPA
[2] https://www.lisenet.com/2016/kerberised-nfs-server-on-rhel-7/

http://www.itp.uzh.ch/~dpotter/howto/kerberos

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