Re: CTF: UEFI HTTP boot support

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.

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