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Subject: Re: [PATCH] IMA: Handle early boot data measurement
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        stephen.smalley.work@gmail.com, casey@schaufler-ca.com
Cc:     tyhicks@linux.microsoft.com, tusharsu@linux.microsoft.com,
        sashal@kernel.org, jmorris@namei.org,
        linux-integrity@vger.kernel.org, selinux@vger.kernel.org,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 25 Aug 2020 14:03:26 -0400
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On Tue, 2020-08-25 at 10:55 -0700, Lakshmi Ramasubramanian wrote:
> On 8/25/20 10:42 AM, Mimi Zohar wrote:
> 
> > > > Please limit the changes in this patch to renaming the functions and/or
> > > > files.  For example, adding "measure_payload_hash" should be a separate
> > > > patch, not hidden here.
> > > > 
> > > 
> > > Thanks for the feedback Mimi.
> > > 
> > > I'll split this into 2 patches:
> > > 
> > > PATCH 1: Rename files + rename CONFIG
> > > PATCH 2: Update IMA hook to utilize early boot data measurement.
> > 
> > I'm referring to introducing the "measure_payload_hash" flag.  I assume
> > this is to indicate whether the buffer should be hashed or not.
> > 
> > Example 1: ima_alloc_key_entry() and ima_alloc_data_entry(0 comparison
> > > -static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
> > > -                                                const void *payload,
> > > -                                                size_t payload_len)
> > > -{
> > > +static struct ima_data_entry *ima_alloc_data_entry(const char *event_name,
> > > +                                                  const void *payload,
> > > +                                                  size_t payload_len,
> > > +                                                  const char *event_data,
> > > +                                                  enum ima_hooks func,
> > > +                                                  bool measure_payload_hash)  <====
> > > +{
> > 
> > Example 2:
> > diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c
> > index a74095793936..65423754765f 100644
> > --- a/security/integrity/ima/ima_asymmetric_keys.c
> > +++ b/security/integrity/ima/ima_asymmetric_keys.c
> > @@ -37,9 +37,10 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
> >          if (!payload || (payload_len == 0))
> >                  return;
> >   
> > -       if (ima_should_queue_key())
> > -               queued = ima_queue_key(keyring, payload, payload_len);
> > -
> > +       if (ima_should_queue_data())
> > +               queued = ima_queue_data(keyring->description, payload,
> > +                                       payload_len, keyring->description,
> > +                                       KEY_CHECK, false);   <===
> >          if (queued)
> >                  return;
> > 
> > But in general, as much as possible function and file name changes
> > should be done independently of other changes.
> > 
> > thanks,
> 
> I agree - but in this case, Tushar's patch series on adding support for 
> "Critical Data" measurement has already introduced 
> "measure_payload_hash" flag. His patch updates 
> "process_buffer_measurement()" to take this new flag and measure hash of 
> the given data.
> 
> My patches extend that to queuing the early boot requests and processing 
> them after a custom IMA policy is loaded.
> 
> If you still think "measure_payload_hash" flag should be introduced in 
> the queuing change as a separate patch I'll split the patches further. 
> Please let me know.

There's a major problem if his changes add new function arguments
without modifying all the callers of the function.  I assume the kernel
would fail to compile properly.

Changing the function parameters to include "measure_payload_hash"
needs to be a separate patch, whether it is part of his patch set or
yours.

Mimi