Re: CTF: UEFI HTTP boot support

On Wed, Jun 17, 2020 at 9:28 PM Dave Cottlehuber <dch_at_skunkwerks.at> wrote:

> On Wed, 17 Jun 2020, at 17:52, Rodney W. Grimes wrote:
> > > Rodney W. Grimes <freebsd-rwg_at_gndrsh.dnsmgr.net> wrote:
> > > > > The "fake cd drive" is in the kernel, loader just copies the iso
> into
> > > > > memory like any other module, and by the time that's done you just
> > > > > reboot into the newly installed system, which again uses
> > > > >
> > > > > vfs.root.mountfrom="cd9660:/dev/md0.uzip"
> > > >                                   ^^^
> > > >
> > > > Argh, the cd9660 confused me, I think your doing a
> > > > "root on mfs/md"?
> > >
> > > loader.conf says
> > >
> > > rootfs_load="yes"
> > > rootfs_name="contents.izo"
> > > rootfs_type="md_image"
> > > vfs.root.mountfrom="cd9660:/dev/md0.uzip"
> > >
> > > contents.izo is uzip'd contents.iso which file(1)
> > > describes as ISO 9660 CD-ROM filesystem data ''
> > >
> > > That's for normal boot, for the loader 'install' command
> > > it expects an uncompressed iso for rootfs.
> >
> > Ok, now the puzzle is how much work to get from a stock FreeBSD .iso
> > image to something that works with this.  Obviously we need a non-stock
> > /boot/loader.conf file, or to type some commands manually at a loader
> > prompt.  I believe the stock GENERIC kernel has the md_root support
> > for this already, so it may not be that hard to do.
>
>
> Hi Miguel, all,
>
> I spent a bit of time on UEFI HTTP Boot earlier in the year in qemu,
> bhyve, and intel NUCs -- until everything in the world went to custard. I
> made some  rough notes[1] and I'll go through them again tonight with a
> fresh build. Hopefully its useful.
>
> What I got stuck on was the final pivot, I have never debugged this setup
> before and I'm still not clear at what point things fail. Olivier's PXE
> booting and BSDRP were a fantastic reference, and I assume they work in
> BSDRP already for him.
>
> Worth noting that LE TLS certs didn't play well with the PXE UEFI
> implementation on my intel NUC, this comes up as a very unhelpful error. At
> least use plain HTTP to get started.
>
> While my notes are amd64 oriented I'm very interested in using this for
> aarch64 locally & in the clowd.
>
> My loader.conf follows:
>
> boot_multicons="YES"
> console="efi,comconsole"
> comconsole_speed="115200"
> boot_verbose="YES"
> # make booting somewhat less painful
> #entropy_cache_load="NO"
> #kern.random.initial_seeding.bypass_before_seeding="0"
> # entropy_cache_load="YES"
> # boot_single="YES"
> tmpfs_load="YES"
> autoboot_delay="-1"
> # dump net vars
> # exec="show boot.netif.hwaddr"
> # exec="show boot.netif.ip"
> # exec="show boot.netif.netmask"
> # exec="show boot.netif.gateway"
> # ensure we have enough ram for our image
> vm.kmem_size=2G
> vfs.root.mountfrom="ufs:/dev/md0"
> # vfs.root.mountfrom.options=ro
> mfs_load="YES"
> mfs_type="md_image"
> mfs_name="/boot/mfs-miniroot"
>
> interesting these are different from what's above in the thread.
>
>
Ah thanks a lot for this and for the references, especially the first one
with all the notes :D

references:
>
> [1]: https://hackmd.io/_at_dch/H1X9RYEZr
> [mfsBSD]: https://mfsbsd.vx.sk/ still 150% awesome
> [olivier]:
> https://blog.cochard.me/2019/02/pxe-booting-of-freebsd-disk-image.html
> [BSDRP]: https://github.com/ocochard/BSDRP
>
> A+
> Dave
>