Re: [RFC PATCH v2 1/4] security/ima: Rewrite tests into new API + fixes

From: Petr Vorel <pvorel@suse.cz>
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: ltp@lists.linux.it, linux-integrity@vger.kernel.org
Subject: Re: [RFC PATCH v2 1/4] security/ima: Rewrite tests into new API + fixes
Date: Wed, 11 Apr 2018 21:03:35 +0200	[thread overview]
Message-ID: <20180411190335.GB25859@x230> (raw)
In-Reply-To: <1523375764.5268.12.camel@linux.vnet.ibm.com>

Hi Mimi,

> > > >  load_policy()
> > ...
> > > >  	cat $1 |
> > > > -	while read line ; do
> > > > -	{
> > > > -		if [ "${line#\#}" = "${line}" ] ; then
> > > > -			echo $line >&4 2> /dev/null
> > > > +	while read line; do
> > > > +		if [ "${line#\#}" = "${line}" ]; then
> > > > +			echo "$line" >&4 2> /dev/null
> > > >  			if [ $? -ne 0 ]; then
> > > >  				exec 4>&-
> > > >  				return 1
> > > >  			fi
> > > >  		fi
> > > > -	}

> > > Originally writing the policy was done one rule at a time, but hasn't
> > > been required for a long time.  dracut and systemd 'cat' the policy
> > > directly to the pseudo file.
> > OK, let's simplify it to catting the content.

> Replacing the builtin policy with a new policy in the initramfs was
> considered safe.  With commit 38d859f991f3 ("IMA: policy can now be
> updated multiple times") the policy can be extended multiple times,
> not only from the initramfs.  For it to be safe to extend the IMA
> policy (eg. CONFIG_IMA_WRITE_POLICY), the policy must be signed.

> These tests assume the policy does not need to be signed.

Is it a good idea to expect that policy must be signed also for older kernels
(kernels before 4.5)?

> Mimi

Kind regards,
Petr