GSoC Idea: per-process filesystem namespaces for FreeBSD

[Warner Losh]

On Tue, Mar 13, 2018 at 7:35 PM, Mark Saad <nonesuch at longcount.org> wrote:

> On Tue, Mar 13, 2018 at 9:25 PM, Rodney W. Grimes
> <freebsd-rwg at pdx.rh.cn85.dnsmgr.net> wrote:
> >> > On Mar 13, 2018, at 7:16 PM, Warner Losh <imp at bsdimp.com> wrote:
> >> >
> >> >
> >> >
> >> >> On Tue, Mar 13, 2018 at 4:31 PM, Mark Saad <nonesuch at longcount.org>
> wrote:
> >> >>
> >> >>> On Mar 13, 2018, at 5:43 PM, Warner Losh <imp at bsdimp.com> wrote:
> >> >>>
> >> >>>> On Tue, Mar 13, 2018 at 1:55 PM, Kristoffer Eriksson <ske at pkmab.se>
> wrote:
> >> >>>>
> >> >>>>
> >> >>>>> On 13 Mar 2018 12:53:18, Theron <theron.tarigo at gmail.com> wrote:
> >> >>>>> For those unfamiliar with Plan9, here is a rough explanation of
> the
> >> >>>>> namespace feature: unlike in Unix, where all processes share the
> same
> >> >>>>> virtual filesystem, each process instead has its own view of the
> >> >>>>> filesystem according to what has been mounted ...
> >> >>>>
> >> >>>> What if I mount a new /etc with a passwd file where root has no
> >> >>>> password, and then run "su"?
> >> >>>>
> >> >>>> (How does Plan9 handle that?)
> >> >>>>
> >> >>>
> >> >>> Plan9 handles that by having a daemon that does user
> authentication. It's
> >> >>> actually more complicated than that, but the machine owner has
> control over
> >> >>> who can do what. For this to work in FreeBSD, either we'd need to
> disallow
> >> >>> the 'file' type for passwd, or we'd have to do something sensible
> with
> >> >>> setuid programs. Well, maybe not 'or' but 'and' since the security
> of
> >> >>> setuid programs depends on the security of the filesystem.... Plan 9
> >> >>> doesn't have these complications, so it can offer a user malleable
> >> >>> filesystem without security risk.
> >> >>>
> >> >>> Warner
> >> >>
> >> >>  A kind of related task; FreeBSD could benefit from : Fixing  and
> improving unionfs / nullfs. There are some weird issues with the current
> unionfs and while it works in many cases there are some edge cases where
> the comments are something like ? FreeBSD needs a proper stacking vfs ...?
>  the examples I can think of ; imagine you have a jail , chroot or even a
> Pxe booted system where you want a a read only null mount from the hosts
> /bin to the targets /bin . Now expand that to most of the base system and
> the mount tmpfs?s for /tep /var/log etc.  most of that works but try to
> unmount it in the wrong order or thrash a unionfs with lots of writes ,on
> top of a tmpfs and things break .
> >> >> So to be clear the project would be to better document the various
> uses of unionfs and nullfs that work , for the ones that do not diving into
> the stacking vfs and seeing if it could be implemented and if it would help
> .
> >> >>
> >> >> Alternatively making FreeBSD multiboot compliant would rock . This
> would allow FreeBSD to natively boot from ipxe or syslinux derivates; thus
> allowing you to boot a working FreeBSD install via a kernel and mfsroot
> image off a web server .
> >> >
> >> > There appears to already be a multiboot.c in the bootloader. I've
> been told by others in the past it just works...
> >> >
> >> > Warner
> >>
> >> I am going down the rabbit hole to see how it works .
> >
> > If you have any questions I am happy to share my working tooling.
> >
>
> I think you are both missing my point. I can boot FreeBSD with ipxe
> loading mfsbsd style setups like this
>
> :freebsd
> initrd ${base-root}/freebsd/mfsroot.gz
> chain ${base-root}/other/memdisk harddisk raw
>
> I want to be able to boot and run it like I would Linux or ESXi with
> the ability to directly load an kernel and a mfsroot/initrd and pass
> kernel loader arguments
>
> :centos674
> set centos674_args edd=off ramdisk_size=50000 nomodeset
> ks=${centos-root}/CentOS6.7_x64/ks/supermicro-4drives.ks
> ksdevice=${net0/mac} verbose ip=dhcp
> root-path=${centos-root}/CentOS6.7_x64/OS/ net.ifnames=0 biosdevname=0
> nousb
> echo ${centos674_args}
> kernel ${base-root}/centos/CentOS6.7_x64/isolinux/vmlinuz
> ${centos674_args}
> initrd ${base-root}/centos/CentOS6.7_x64/isolinux/initrd.img


FreeBSD takes all the arguments that DHCP supplies as loader / kernel env
variables (and if that's not working, I'll fix it). This is a recent
feature and might not be widely documented.

Warner


> > ...
> >
> > isc-dhcp from ports,
> > base system tftp setup via inetd
> > some bits of syslinix 6.03
> > proper set of iPXE.exe binaries built with iSCSI, http and nfs support,
> > you wont need iSCSI, I use that for other things like Windblows.
> > I boot direct from iPXE to nfs loaded kernel, only thing tftp is used
> > for is getting a modern version of iPXE onto the booting system.
> >
> > iPXE loads a menu.ipxe to allow OS selection.
> > menu.ipxe loads /boot/pxeboot via NFS
> > YOU SHALL HAVE ISSUES HERE most pxeboot images are broken
> > pxeboot loads kernel via NFS
> > kernel runs, end up in /etc/rc.diskless that does the rest of the magic.
> >
> >
> > --
> > Rod Grimes
> rgrimes at freebsd.org
>
>
>
> --
> mark saad | nonesuch at longcount.org
>