Re: How is policy.31 created from modules under /usr/share/selinux

[Richard Haines <richard_c_haines@btinternet.com>]

On Wed, 2020-12-09 at 19:42 +0530, Ashish Mishra wrote:
> Hi Richard ,
> 
> Will check with the monolithic policy to check the behavior of the
> semodule as you suggested.
> 
> Is there any similar approach / workaround for modular one?

I've only had a quick look at code and I could see two ways to fix:
1) Modify the Rules.modular part of the make file to move or copy the
policy and file contexts set of files over to $DESTDIR.
2) Modify semodule/semanage to handle $DESTDIR. I think this would be
more difficult to fix as lots go on here.

Maybe Chris could comment.

> 
> Thanks for pointers again.
> 
> Ashish
> 
> 
> 
> 
> 
> On Wed, Dec 9, 2020 at 3:23 PM Richard Haines
> <richard_c_haines@btinternet.com> wrote:
> > 
> > On Tue, 2020-12-08 at 21:28 +0530, Ashish Mishra wrote:
> > > Hi Chris ,
> > > 
> > > Continuing on the inputs Richard shared , I was able to zero down
> > > to
> > > the problem.
> > > To recreate , step  can be directly tested by command mentioned
> > > in
> > > step-c
> > > 
> > > a) I am having custom-rootfs under which I am trying to get the
> > > refpolicy installed.
> > > 
> > > b) By using make load DESTDIR=/tmp/custom-rootfs , the setup
> > > reaches
> > > to state where
> > >      # semodule -s refpolicy -i NAME-OF-MODULE is triggered for
> > > every
> > > module under /tmp/custom-rootfs/usr/share/selinux/refpolicy
> > >      ==> This semodule behavior is causing the problem.
> > > 
> > > c) By default semodule install the file under /etc/selinux of
> > > HOST
> > > system rather than /tmp/custom-rootfs/etc/selinux
> > >     This behaviour can be recreated / verified by :
> > >     # semodule  -s selinux-store-name -i sample.pp
> > >     This instruction creates an entry of selinux-store-name and
> > > creates policy.32 file there .
> > >      ==> Instead , here i wanted the file to be created under
> > > /tmp/custom-rootfs/etc/selinux & not /etc/selinux
> > > 
> > > d) Currently trying to look at the file from where this
> > > instruction
> > > is
> > > executed & then check if
> > >     somehow semodule can be made to use /tmp/custom-
> > > rootfs/etc/selinux
> > > over default /etc/selinux
> > > 
> > > Thanks for sharing the info w.r.t your use case , will look at
> > > them .
> > > They can help me to understand the process in a better way.
> > > 
> > > Please feel free to revert if any further details are required or
> > > if
> > > i
> > > am missing any aspect .
> > 
> > I've been AWOL for a few days so just picking up on this query. I
> > can
> > now see the problem as described. If you generate a monolithic
> > policy
> > (MONOLITHIC=y) using sequence below it all works. However if you
> > build
> > a modular policy (MONOLITHIC=n), then semodule will install the
> > final
> > binary policy in /etc/selinux/refpolicy/policy regardless of
> > DESTDIR.
> > 
> > I guess semodule should obey orders??
> > 
> > export DESTDIR=/tmp/custom-embedded-rootfs
> > mkdir refpol
> > cd refpol
> > git clone https://github.com/SELinuxProject/refpolicy.git
> > Edit build.conf file to requirements (e.g. NAME = refpolicy etc.)
> > make install-src
> > cd /tmp/custom-embedded-rootfs/etc/selinux/refpolicy/src/policy
> > make conf
> > make load
> > 
> > 
> > 
> > 
> > > 
> > > Thanks  ,
> > > Ashish
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > On Tue, Dec 8, 2020 at 9:06 PM Chris PeBenito <pebenito@ieee.org>
> > > wrote:
> > > > 
> > > > (SELinux main mail list to BCC since this is a refpolicy
> > > > question.)
> > > > 
> > > > On 12/7/20 8:26 AM, Ashish Mishra wrote:
> > > > >   4)  Further debugging I can confirm that the final binary
> > > > > (policy.31)
> > > > > seems to be
> > > > >        using HARD-CODDED location of /etc/selinux instead of
> > > > > what
> > > > > is
> > > > > being passed as DESTDIR.
> > > > >       The policy.31 is created not at custom-embedded-rootfs
> > > > > location.
> > > > > 
> > > > >        Due to this :
> > > > >          - policy.31 is created in
> > > > > /etc/selinux/refpolicy/policy/policy.31
> > > > >            instead of what i was expecting at
> > > > > /tmp/custom-embedded-
> > > > > rootfs/etc/selinux/refpolicy/policy/policy.31
> > > > >            as DESTDIR=${ROOT}  and i do get *.pp at the
> > > > > expected
> > > > > location of /tmp/custom-embedded-
> > > > > rootfs/etc/selinux/refpolicy/src/policy
> > > > >                   ${MAKE} -C
> > > > > ${ROOT}/etc/selinux/${PKG}/src/policy load
> > > > > DESTDIR=${ROOT}
> > > > 
> > > > 
> > > > I can't reproduce your issue.  I use monolithic policy
> > > > regularly in
> > > > the way
> > > > you're using it.
> > > > 
> > > > Here's the Makefile variables:
> > > > 
> > > >  From Makefile:
> > > >    topdir := $(DESTDIR)/etc/selinux
> > > >    installdir := $(topdir)/$(strip $(NAME))
> > > >    policypath := $(installdir)/policy
> > > > 
> > > >  From Rules.monolithic:
> > > >    loadpath = $(policypath)/$(notdir $(polver))
> > > > 
> > > > $(notdir $(polver)) is "policy.31" and NAME is what you have in
> > > > build.conf, e.g.
> > > > "refopolicy".
> > > > 
> > > > 
> > > > Then the install target for monolithic looks like this (with
> > > > "echo"s removed):
> > > > 
> > > > $(loadpath): $(policy_conf)
> > > >          @$(INSTALL) -d -m 0755 $(@D)
> > > >          $(verbose) $(CHECKPOLICY) -U $(UNK_PERMS)  $^ -o $@
> > > > 
> > > > --
> > > > Chris PeBenito
> > 
> >