ZFS & NFS

[Slawa Olhovchenkov]

On Sat, Mar 17, 2012 at 12:13:32AM +0400, Slawa Olhovchenkov wrote:

> On Fri, Mar 16, 2012 at 07:34:56PM +0100, Patrick M. Hausen wrote:
> 
> > Hello,
> > 
> > Am 16.03.2012 um 18:42 schrieb Slawa Olhovchenkov:
> > > On Fri, Mar 16, 2012 at 06:32:43PM +0100, Patrick M. Hausen wrote:
> > > 
> > >> Hello,
> > >> 
> > >> Am 16.03.2012 um 18:20 schrieb Slawa Olhovchenkov:
> > >>> I do NFSv3 export of ZFS.
> > >>> root from remote host create files on ZFS witch uid 2^32-2:
> > >>> 
> > >>> # ls -l /usr/ports/packages32/
> > >>> total 6
> > >>> drwxr-xr-x  2 4294967294  wheel  5 Mar 17 00:57 All
> > >>> drwxr-xr-x  2 4294967294  wheel  5 Mar 17 00:57 Latest
> > >>> drwxr-xr-x  2 4294967294  wheel  3 Mar 17 00:52 archivers
> > >>> drwxr-xr-x  2 4294967294  wheel  4 Mar 17 00:57 lang
> > >> 
> > >> 
> > >> Yes? This is expected behaviour of NFS. If you don't want that, try
> > >> 
> > >> 	-maproot=root
> > >> 
> > >> either in sharenfs option to zfs or /etc/exports, whichever it is you are using.
> > > 
> > > hmm...
> > > nobody:*:65534:65534:Unprivileged user:/nonexistent:/usr/sbin/nologin
> > > 
> > > 65534 != 4294967294 (2^16-2 != 2^32-2)
> > > 
> > > Also, I am think ZFS+NFS will be wrong for UID>2^15.
> > 
> > I admit I overlooked that one (16 vs 32 bits). But if I'm not mistaken, NFS does not care
> > a bit about the name of the user "nobody" or the UID in /etc/passwd or what-have-you.
> > It simply sets the UID of remote root (UID 0) to the value -1.
> 
> https://blogs.oracle.com/taylor22/entry/nfs_root_access_on_sun
> 
> ===
> In a default configuration, a Solaris NFS server maps "root" access to
> "nobody". 
> ===
> 
> http://pubs.opengroup.org/onlinepubs/9629799/chap12.htm#tagcjh_13_03_03
> 
> ===
> In some operating systems, a particular user (on UNIX systems, the
> user ID 0) has access to all files, no matter what permission and
> ownership they have. This super-user permission might not be allowed
> on the server, since anyone who can become super-user on their client
> could gain access to all remote files. A UNIX server by default maps
> user ID 0 to a distinguished value (UID_NOBODY), as well as mapping
> the groups list, before doing its access checking. A server
> implementation may provide a mechanism to change this mapping. This
> works except for NFS Version 3 protocol root file systems (required
> for diskless NFS Version 3 protocol client support), where super-user
> access cannot be avoided. Export options are used, on the server, to
> restrict the set of clients allowed super-user access. 
> ===
> 
> /usr/include/sys/_types.h:typedef       __uint32_t      __uid_t;
> 
> > And 4294967294 happens to be -1 in 32 bits signed. So - possibly this is built into
> > ZFS this way. I would at least give the sharenfs="..." options a try ...
> 
> 4294967294 happens to be -2 in 32 bits signed.
> And I see type of UID (uid_t) is unsigned.

And also,
/usr/include/sys/conf.h:#define         UID_NOBODY 65534