On Tue, 2019-05-28 at 11:25 -0400, Steve Dickson wrote: > > On 5/21/19 3:58 PM, Trond Myklebust wrote: > > On Tue, 2019-05-21 at 15:06 -0400, Chuck Lever wrote: > > > > On May 21, 2019, at 2:17 PM, Trond Myklebust < > > > > trondmy@xxxxxxxxxxxxxxx> wrote: > > > > > > > > On Tue, 2019-05-21 at 13:40 -0400, Chuck Lever wrote: > > > > > Hi Trond - > > > > > > > > > > > On May 21, 2019, at 8:46 AM, Trond Myklebust < > > > > > > trondmy@xxxxxxxxx > > > > > > wrote: > > > > > > > > > > > > The following patchset adds support for the 'root_dir' > > > > > > configuration > > > > > > option for nfsd in nfs.conf. If a user sets this option to > > > > > > a > > > > > > valid > > > > > > directory path, then nfsd will act as if it is confined to > > > > > > a > > > > > > chroot > > > > > > jail based on that directory. All paths in /etc/exporfs and > > > > > > from > > > > > > exportfs are then resolved relative to that directory. > > > > > > > > > > What about files under /proc that mountd might access? I > > > > > assume > > > > > these > > > > > pathnames are not affected. > > > > > > > > > That's why we have 2 threads. One thread is root jailed using > > > > chroot, > > > > and is used to talk to knfsd. The other thread is not root > > > > jailed > > > > (or > > > > at least not by root_dir) and so has full access to /etc, > > > > /proc, > > > > /var, > > > > ... > > > > > > > > > Aren't there also one or two other files that maintain export > > > > > state > > > > > like /var/lib/nfs/rmtab? Are those affected? > > > > > > > > See above. They are not affected. > > > > > > > > > IMHO it could be less confusing to administrators to make > > > > > root_dir an > > > > > [exportfs] option instead of a [mountd] option, if this is > > > > > not a > > > > > true > > > > > chroot of mountd. > > > > > > > > It is neither. I made in a [nfsd] option, since it governs the > > > > way > > > > that > > > > both exportfs and mountd talk to nfsd. > > > > > > My point is not about implementation, it's about how this > > > functionality > > > is presented to administrators. > > > > > > In nfs.conf, [nfsd] looks like it controls what options are > > > passed > > > via > > > rpc.nfsd. That still seems like a confusing admin interface. > > > > > > IMO admins won't care about who is talking to whom. They will > > > care > > > about > > > how the export pathnames are interpreted. That seems like it > > > belongs > > > squarely with the exportfs interface. > > > > > > > With the exportfs interface, yes. However it is not specific to the > > exportfs utility, so to me [exportfs] is more confusing than what > > exists now. > > > > OK, so what if we put it in [general] instead, and perhaps rename > > it > > "export_rootdir"? > > > I'm just catching up... my apologies tartness... > > So setting root_dir effects *all* exports in /etc/exports? > If that is the case, that one variable can change hundreds > of export... is that what we really want? > > Wouldn't be better to have a little more granularity? Can you explain what you mean? The intention here is that if you have all your exported filesystems set up in a subtree under /mnt/my/exports, then you can remove that unnecessary prefix. So, for instance, if I'm trying to export /mnt/my/exports/foo and /mnt/my/exports/bar, then I can make those two filesystems appear as /foo, and /bar to the remote clients. If an admin wants to rearrange all the paths in /etc/exports, and make a custom namespace, then that is possible using bind mounts: just create a directory /my_exports, and use mount --bind to attach the necessary mountpoints into the right spots in /my_exports, then use export_rootdir to remove the /my_exports prefix. > As for where root_dir should go, I think it makes senses > to create a new [exportfs] section and have mountd read it > from there. I think that would be more straightforward if > we continue with the big hammer approach where any and all > exports are effected. > Fair enough, I can add the [exports] section if you all agree that is an appropriate place. -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
