selinux + livecd-creator, May 20, 2008

Eric Paris eparis at
Tue May 20 19:12:00 UTC 2008

running a system with selinux enforcing/permissive (doesn't matter) and
attempting to run livecd-creator with selinux --disabled results in
passwd espoloding.  passwd called is_selinux_enabled() which says yes
since /proc/mounts has an selinuxfs and the passwd calls
selinux_enforcing() which explodes when it can't find
a /selinux/enforce.  First discussion was to change /proc/mounts to hide
the selinuxfs, sounds like a good plan until I realize /proc/mounts is
actually link to /proc/self/mounts and that its getting way to complex
tying to set up FS namespaces or whatever this is going to take.  Right
now I'm thinking of creating a /selinux with enforce=0 in all cases
inside the chroot, anyone see a problem with that?  (I could also work
on fixing passwd, but i'm trying to be as 'backwards compatible' as

do we have an interface to see what is actually in security.xattr?
Making use of the wonderful new deferred selinux context patch set from
the kernel I get beautiful message like:

/sbin/restorecon reset /sbin/dump context

The file wasn't really "unlabeled_t" it just wasn't a valid label on the
host machine.  Since restorecon/fixfiles runs over the same files like 3
times during a livecd creation this gets rather annoying.  Do we have an
interface I could use to make restorecon do the right comparison here?

***allow unlabeled_t fs_t:filesystem associate:
anyone have thoughts on how we want to handle this?  I can probably do
some sort of fscontext= mount magic once i figure out the right fs we
are talking about and where the script does the mount.  But then host
policy is going to need rules to allow everything that can associate
with fs_t with fs_allow_unlabeled_t.  Is that hard?  I assume Dan can
help me out there.  Does this sound like a good way to solve it?  Is
hard coding some 'fscontext=' line into livecd-creator a good idea?
Should I just generically allow it?  Should I make livecd-creator load a
policy module to start off and unload it at the end?   (I don't like
this idea since I've learned livecd-creator can be pretty fragile and
leave things half done/half undone...)

***Invalid prefix *
On rawhide we just dropped that stuff altogether.  Can we do the same on
F8?  Is it actually causing a problem?  Dan, any hints on how I can make
the system lie to you?

Needless to say, I successfully built an F8 livecd with types not known
tot he host system on rawhide today, booted, and logged in.

tomorrow I spend more time typing to make the policy for livecd-creator
a bit better.....


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