xattr support in live-installer?

[Colin Watson <cjwatson@debian.org>]

Hi,

https://launchpad.net/bugs/1302192 reports ping not being setuid root
after installation from squashfs-based media.  I've reproduced this with
the Ubuntu server installer, which uses live-installer to install the
base system (much faster than running debootstrap).  I haven't
explicitly tested Debian live media, but I suspect they'll suffer from
the same problem.

The question is what to do about it.  live-installer uses busybox tar to
shovel files around, and busybox tar doesn't support xattr.  We could do
something with getcap/setcap - indeed getcap supports recursive search
and setcap can read capabilities in bulk from standard input, so this
shouldn't need to be too slow - but we don't have those tools in d-i
right now.

Would it make sense to modify attr to build udebs, then change
live-installer to do a getcap/setcap run after transferring files with
tar?  I think this is probably going to be simpler than adding xattr
support to busybox tar (in GNU tar that depends on a specific archive
format, so I'm guessing it's not exactly trivial).  Even if we did go
for the latter approach instead, we'd probably still need at least a
libattr1-udeb.

Thoughts?

Thanks,

-- 
Colin Watson                                       [cjwatson@debian.org]