12:01 a.m.
On 4/13/2016 10:00 AM, John Ferlan wrote:
On 04/13/2016 09:23 AM, TomK wrote:
> On 4/13/2016 1:33 AM, Martin Kletzander wrote:
>> On Tue, Apr 12, 2016 at 06:24:16PM -0400, TomK wrote:
>>> On 4/12/2016 5:08 PM, John Ferlan wrote:
>>>> Having/using a root squash via an NFS pool is "easy" (famous
last
>>>> words)
>>>>
>>>> Create some pool XML (taking the example I have)
>>>>
>>>> % cat nfs.xml
>>>> <pool type='netfs'>
>>>> <name>rootsquash</name>
>>>> <source>
>>>> <host name='localhost'/>
>>>> <dir path='/home/bzs/rootsquash/nfs'/>
>>>> <format type='nfs'/>
>>>> </source>
>>>> <target>
>>>> <path>/tmp/netfs-rootsquash-pool</path>
>>>> <permissions>
>>>> <mode>0755</mode>
>>>> <owner>107</owner>
>>>> <group>107</group>
>>>> </permissions>
>>>> </target>
>>>> </pool>
>>>>
>>>> In this case 107:107 is qemu:qemu and I used 'localhost' as the
>>>> hostname, but that can be a fqdn or ip-addr to the NFS server.
>>>>
>>>> You've already seen my /etc/exports
>>>>
>>>> virsh pool-define nfs.xml
>>>> virsh pool-build rootsquash
>>>> virsh pool-start rootsquash
>>>> virsh vol-list rootsquash
>>>>
>>>> Now instead of
>>>>
>>>> <disk type='file' device='disk'>
>>>> <source
file='/var/lib/one//datastores/0/38/disk.0'/>
>>>> <target dev='hda'/>
>>>> <driver name='qemu' type='qcow2'
cache='none'/>
>>>> </disk>
>>>>
>>>> Something like:
>>>>
>>>> <disk type='volume' device='disk'>
>>>> <driver name='qemu' type='qemu'
cache='none'/>
>>>> <source pool='rootsquash' volume='disk.0'/>
>>>> <target dev='hda'/>
>>>> </disk>
>>>>
>>>> The volume name may be off, but it's perhaps close. I forget how to
do
>>>> the readonly bit for a pool (again, my focus is elsewhere).
>>>>
>>>> Of course you'd have to adjust the nfs.xml above to suit your
>>>> environment and see what you see/get. The privileges for the pool and
>>>> volumes in the pool become the key to how libvirt decides to
"request
>>>> access" to the volume. "disk.1" having read access is
probably not an
>>>> issue since you seem to be using it as a CDROM; however,
"disk.0" is
>>>> going to be used for read/write - thus would have to be appropriately
>>>> configured...
>>>>
>>> Thanks John! Appreciated again.
>>>
>>> No worries, handle what's on the plate now and earmark this for checking
>>> once you have some free cycles. I can temporarily hop on one leg by
>>> using Martin Kletzander's workaround (It's a POC at the moment).
>>>
>>> I'll have a look at your instructions further but wanted to find out if
>>> that config nfs.xml is a one time thing correct? I'm spinning these up
>>> at will via the OpenNebula GUI and if I have update for each VM, that
>>> breaks the Cloud provisioning. I'll go over your notes again. I'm
>>> optimistic. :)
>>>
>> The more I'm thinking about it, the more I am convinced that the
>> workaround is actually not a workaround. The only thing you need to do
>> is having execute for others (precisely for 'nobody' on the nfs share)
>> in the whole path on all directories. Without that even the pool won't
>> be usable from libvirt. However it does not pose any security issue as
>> it only allows others to check the path. When qemu is launched, it has
>> the proper "label", meaning uid:gid to access the file so it will be
>> able to read/write or whatever permissions you set there. It's just
>> that libvirt does some checks that the path exists for example.
>>
>> Hope that's understandable and it will resolve your issue permanently.
>>
>> Have a nice day,
>> Martin
>>
>>
>> _______________________________________________
>> libvirt-users mailing list
>> libvirt-users(a)redhat.com
>> https://www.redhat.com/mailman/listinfo/libvirt-users
> The only reason I said that this might be a 'workaround' is due to John
> Farlan commenting that he'll look at this later on. Ideally the
> opennebula community keeps the other permissions to nill and presumably
> they work on NFSv3 per the forum topic I included earlier from them.
> But if setting the permissions on nobody to allow for the functionality,
> I would be comfortable with that.
>
Martin and I were taking different paths... But yes, it certainly makes
sense given your error message about canonical path and the need for
eXecute permissions... I think I started wondering about that first, but
then jumped into the NFS pool because that's what my reference point is
for root-squash. Since root squash essentially sends root requests as
"nfsnobody" (IOW: others not the user or group), then the "o+x"
approach
is the solution if you're going directly at the file.
John
Yes, appears the o+x is the only way right now. It definitely tries to
access the share as root though, on CentOS 7 since I also tried to add
nfsnobody and nobody to the oneadmin group and that did not work
either. Seems OpenNebula doesn't have this issue with NFSv3 running on
Ubuntu:
[root@mdskvm-p01 ~]# rmdir /tmp/netfs-rootsquash-pool
[root@mdskvm-p01 ~]# cat nfs.xml
<pool type='netfs'>
<name>rootsquash</name>
<source>
<host name='opennebula01'/>
<dir path='/var/lib/one'/>
<format type='nfs'/>
</source>
<target>
<path>/tmp/netfs-rootsquash-pool</path>
<permissions>
<mode>0755</mode>
<owner>9869</owner>
<group>9869</group>
</permissions>
</target>
</pool>
[root@mdskvm-p01 ~]#
[root@mdskvm-p01 ~]#
[root@mdskvm-p01 ~]# virsh pool-define nfs.xml
Pool rootsquash defined from nfs.xml
[root@mdskvm-p01 ~]# virsh pool-build rootsquash
Pool rootsquash built
[root@mdskvm-p01 ~]# virsh pool-start rootsquash
error: Failed to start pool rootsquash
error: cannot open path '/tmp/netfs-rootsquash-pool': Permission denied
[root@mdskvm-p01 ~]# virsh vol-list rootsquash
error: Failed to list volumes
error: Requested operation is not valid: storage pool 'rootsquash' is
not active
[root@mdskvm-p01 ~]# ls -altri /tmp/netfs-rootsquash-pool
total 4
133 drwxrwxrwt. 14 root root 4096 Apr 14 00:05 ..
68785924 drwxr-xr-x 2 oneadmin oneadmin 6 Apr 14 00:05 .
[root@mdskvm-p01 ~]#
[root@mdskvm-p01 ~]# id oneadmin
uid=9869(oneadmin) gid=9869(oneadmin)
groups=9869(oneadmin),992(libvirt),36(kvm)
[root@mdskvm-p01 ~]# id nobody
uid=99(nobody) gid=99(nobody) groups=99(nobody),9869(oneadmin)
[root@mdskvm-p01 ~]# id nfsnobody
uid=65534(nfsnobody) gid=65534(nfsnobody)
groups=65534(nfsnobody),9869(oneadmin)
[root@mdskvm-p01 ~]# id root
uid=0(root) gid=0(root) groups=0(root)
[root@mdskvm-p01 ~]#
[root@mdskvm-p01 ~]# ps -ef|grep -i libvirtd
root 352 31058 0 00:31 pts/1 00:00:00 grep --color=auto -i
libvirtd
root 1459 1 0 Apr11 ? 00:07:40 /usr/sbin/libvirtd
--listen --config /etc/libvirt/libvirtd.conf
[root@mdskvm-p01 ~]#
[root@mdskvm-p01 ~]# umount /var/lib/one
[root@mdskvm-p01 ~]# mount --no-canonicalize /var/lib/one
[root@mdskvm-p01 ~]# umount /var/lib/one
[root@mdskvm-p01 ~]# mount /var/lib/one
[root@mdskvm-p01 ~]# mount|tail -n 1
192.168.0.70:/var/lib/one on /var/lib/one type nfs4
(rw,relatime,vers=4.0,rsize=8192,wsize=8192,namlen=255,soft,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.0.60,local_lock=none,addr=192.168.0.70)
[root@mdskvm-p01 ~]# umount /var/lib/one
[root@mdskvm-p01 ~]# mount --no-canonicalize /var/lib/one
[root@mdskvm-p01 ~]# mount|tail -n 1
192.168.0.70:/var/lib/one on /var/lib/one type nfs4
(rw,relatime,vers=4.0,rsize=8192,wsize=8192,namlen=255,soft,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.0.60,local_lock=none,addr=192.168.0.70)
[root@mdskvm-p01 ~]# su - oneadmin
Last login: Thu Apr 14 00:27:59 EDT 2016 on pts/0
[oneadmin@mdskvm-p01 ~]$ virsh -d 1 --connect qemu:///system create
/var/lib/one//datastores/0/47/deployment.0
create: file(optdata): /var/lib/one//datastores/0/47/deployment.0
error: Failed to create domain from
/var/lib/one//datastores/0/47/deployment.0
error: can't canonicalize path '/var/lib/one//datastores/0/47/disk.1':
Permission denied
[oneadmin@mdskvm-p01 ~]$
CONTROLLER ( NFS Server )
[oneadmin@opennebula01 one]$ ls -ld
/var{,/lib{,/one{,/datastores{,/0{,/47{,/disk.1}}}}}}
drwxr-xr-x. 19 root root 4096 Apr 4 21:26 /var
drwxr-xr-x. 28 root root 4096 Apr 13 03:30 /var/lib
drwxr-x---. 12 oneadmin oneadmin 4096 Apr 14 00:40 /var/lib/one
drwxrwxr-x 6 oneadmin oneadmin 46 Mar 31 02:44 /var/lib/one/datastores
drwxrwxr-x 8 oneadmin oneadmin 60 Apr 13 23:31
/var/lib/one/datastores/0
drwxrwxr-x 2 oneadmin oneadmin 68 Apr 13 23:32
/var/lib/one/datastores/0/47
-rw-r--r-- 1 oneadmin oneadmin 372736 Apr 13 23:32
/var/lib/one/datastores/0/47/disk.1
[oneadmin@opennebula01 one]$
NODE ( NFS Client )
[oneadmin@mdskvm-p01 ~]$ ls -ld
/var{,/lib{,/one{,/datastores{,/0{,/47{,/disk.1}}}}}}
drwxr-xr-x. 21 root root 4096 Apr 11 07:10 /var
drwxr-xr-x. 45 root root 4096 Apr 13 04:11 /var/lib
drwxr-x--- 12 oneadmin oneadmin 4096 Apr 14 00:39 /var/lib/one
drwxrwxr-x 6 oneadmin oneadmin 46 Mar 31 02:44 /var/lib/one/datastores
drwxrwxr-x 8 oneadmin oneadmin 60 Apr 13 23:31
/var/lib/one/datastores/0
drwxrwxr-x 2 oneadmin oneadmin 68 Apr 13 23:32
/var/lib/one/datastores/0/47
-rw-r--r-- 1 oneadmin oneadmin 372736 Apr 13 23:32
/var/lib/one/datastores/0/47/disk.1
[oneadmin@mdskvm-p01 ~]$
Cheers,
Tom K.
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