linux-kernel - Re: [RFC PATCH v3 2/2] ima: force re-appraisal on filesystems with FS_IMA_NO

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Date:   Mon, 29 Jan 2018 11:33:05 -0500
From:   Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:     "Serge E. Hallyn" <serge@...lyn.com>,
        Alban Crequy <alban.crequy@...il.com>
Cc:     alban@...volk.io, dongsu@...volk.io, iago@...volk.io,
        linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, miklos@...redi.hu,
        viro@...iv.linux.org.uk, dmitry.kasatkin@...il.com,
        james.l.morris@...cle.com, seth.forshee@...onical.com,
        hch@...radead.org
Subject: Re: [RFC PATCH v3 2/2] ima: force re-appraisal on filesystems with
 FS_IMA_NO_CACHE

Hi Alban,

On Thu, 2018-01-25 at 06:56 -0500, Mimi Zohar wrote:
> > > @@ -228,9 +229,28 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
> > >  				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
> > >  				 IMA_ACTION_FLAGS);
> > >  
> > > -	if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags))
> > > -		/* reset all flags if ima_inode_setxattr was called */
> > > +	/*
> > > +	 * Reset the measure, appraise and audit cached flags either if:
> > > +	 * - ima_inode_setxattr was called, or
> > > +	 * - based on filesystem feature flag
> > > +	 * forcing the file to be re-evaluated.
> > > +	 */
> > > +	if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags)) {
> > >  		iint->flags &= ~IMA_DONE_MASK;
> > > +	} else if (inode->i_sb->s_type->fs_flags & FS_IMA_NO_CACHE) {
> > > +		if (action & IMA_MEASURE) {
> > > +			iint->measured_pcrs = 0;
> > > +			iint->flags &=
> > > +			    ~(IMA_COLLECTED | IMA_MEASURE | IMA_MEASURED);
> > > +		}
> > > +		if (action & IMA_APPRAISE)
> > > +			iint->flags &=
> > > +			    ~(IMA_COLLECTED | IMA_APPRAISE | IMA_APPRAISED |
> > > +			      IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK);
> > > +		if (action & IMA_AUDIT)
> > > +			iint->flags &=
> > > +			    ~(IMA_COLLECTED | IMA_AUDIT | IMA_AUDITED);
> > > +	}
> > > 
> 
> Alban, I don't know what I was thinking, but this can be simplified
> like for the IMA_CHANGE_XATTR case.  Except in the IMA_CHANGE_XATTR
> case, "measured_pcrs" was already reset, whereas in this case
> "measured_pcrs" needs to be reset.

Did you get a chance to make the change and test it?

Mimi