From: Herbert Poetzl (herbert_at_13thfloor.at)
Date: Sat 13 Aug 2005 - 02:43:37 BST
On Fri, Aug 12, 2005 at 09:03:39PM -0400, Stephen Harris wrote:
> On Fri, Aug 12, 2005 at 01:55:30AM +0200, Herbert Poetzl wrote:
> > On Thu, Aug 11, 2005 at 09:56:20AM -0400, Stephen Harris wrote:
> > >
> > > [root]/home/sweh
> > > backup.pts/2% mount -r backup:/RedHat/updates/core1 /vservers/webssh/RedHat
> >
> > no idea 'what' filesystem you did mount here, but to me
> > it looks like a network filesystem (i.e. nfs)
>
> Yes, it is. In fact it's an NFS mount from myself to myself; I can't
> use bind mounts because I want the vservers to only have read-only
> access to the filesystem, and bind mounts don't (or didn't, last time
> I tried) allow changes in permissions between the original location
> and the bound location.
yeah, right, that's where my BME (Bind Mount Extension)
patches come into play (fixing this mainline 'bug/feature')
> > > backup.pts/2% vserver webssh enter
> > > SIOCSIFBRDADDR: Cannot assign requested address
> > > SIOCSIFFLAGS: Cannot assign requested address
> >
> > this is a good sign of a broken config (network wise)
>
> Network wise, it actually works. I had thought this had come from the
> guest OS trying to do stuff, but I'm a vserver newbie. Hmm.
>
> Ah... maybe it's because I'm using a 10.* address but have a
> 255.255.255.0 netmask; I left IPROOTMASK and IPROOTBCAST unset, so
> _maybe_ it's attempting to calculate based on a 255.0.0.0 mask, and
> failing to set them. Hmm, no, that's not it. I just tried.
>
> Could this be ipv6, perhaps? I'm not using ipv6.
>
> I had noticed that inside the vserver, an "ifconfig -a" shows _all_
> the hosts IP addresses, and not just the one in the vserver.
>
> But otherwise it all works.
>
> > > ipv4root is now 10.0.0.2
>
> This is the correct address.
>
> > > New security context is 49173
> >
> > and just as sidenote, you should avoid dynamic context
> > ids, unless you are looking for trouble :)
>
> OK; I'm new vserver newbie and just took the defaults which said
>
> # Select an unused context (this is optional)
> # The default is to allocate a free context on the fly
> # In general you don't need to force a context
what defaults are those?
> but I'll take your advice and have assigned fixed contexts now (10001
> and 10002).
>
> > > bash: ulimit: core file size: cannot modify limit: Invalid argument
> >
> > this looks evem more like a debian^Wconfig issue, where
> > you specified a limit (maybe -H or -S) without raising
> > the proper other limit (specify -HS to solve that)
>
> No, it appears to be from my .profile inside the guest. For historical
> reasons I had "ulimit -Sc unlimited" for my own account, and this
> seems to be read when entering the guest.
>
> > this is a different IP than the one before, NFS isn't
> > handled that well on 2.4, but of course, the guest
> > will send requests with 10.0.0.3 now, which, in turn
> > might lead to the Permission denied (if your server
> > does not allow 10.0.0.3 to access the share)
>
> The server allows the whole 10.0.0.* network (my home network).
>
> Will the guest make a request? The guest hasn't actually made the
> mount; the host has made the mount and has made it available to the
> guest. So will the request come from the guest's IP address, or will
> it fall through to the host, and the host make the request.
the host will make the request, but with the guest's ip
(NFS isn't really supported with 2.4/1.2.x)
> Ah, OK... some network snooping... the request comes from the guest IP
> address. That's... broken! The mount came from the host IP address but
> the nfs requests came from the guest IP adrress. Hmm.. I'm surprised
> it ever worked!
well, it is how networking works right now :)
> OK, what's the best way of providing a filesystem to the guest with
> read-only privs? Clearly NFS is a kludge.
see BME note above ...
> Huh.. that's odd... I just shut down _all_ vservers and restarted them
> and now the mount works in both vserver instances.... that seems like
> something confused, but I can probably live with it; my mounts have so
> far worked.
>
> But it does look like I need better solution; how to make a filesystem
> available to a vserver with differnt permissions than the host has?
>
> > hmm, and IDE hotswapping did work with 2.4 but does
> > not with 2.6? interesting ...
>
> Yeah, it's very annoying. Alan Cox has a lot to say about it!
he probably has ... fixing it would be better, though :)
best,
Herbert
> --
>
> rgds
> Stephen
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