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

[Richard Haines <richard_c_haines@btinternet.com>]

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
> 
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> 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