[Xen-devel] Re: [Xense-devel] [PATCH] ACM: adding C-support for policy translation and labeling support for domains

[Reiner Sailer <sailer@xxxxxxxxxx>]

Hi Dave,

we are introducing the get_ssid ACM
command to allow  ACM policy-specific decisions 
and enforcement in  policy-aware
domains.

One can call back into the hypervisor
for policy decisions having the benefit you are 
naming (transparency). However doing
this for every IP packet, for example, seems not efficient.
Consequently, you'll end up establishing
decision cashes in the domains. Then you have the same
problem as before (change in policy)
without the performance benefit. If transparency
(policy hiding) is the most important
factor, then such a solution has merit. Another benefit of
getting the whole ssid is that you can
re-use this information for other decisions since you get
all the types of a domain, not just
a yes/no decision.

Nothing speaks against having an optional
"acm_decision" call that can be used 
by domains that don't  want to
make informed decisions but blindly call the ACM 
(hypervisor call++ overhead) each time
they make a decisions. Such a call might prove useful
where decisions are made very infrequently.
For example, a virtual block device domain owning a 
hard drive and allowing other domains
to mount certain logical partitions might just ask the ACM for 
a decision  when deciding about
accepting a mount-request from a domain to a logical partition
(right now, the virtual block device
domain is dom0 but this could be refined in the future when other 
domains can 'own' peripherals).

Regards
Reiner

xense-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 08/31/2005
07:11:44 PM:

> I'm not clear why the getssid() needs to be introduced.  Isn't
the 
> problem better solved by introducing new object managers?  With
the 
> getssid(), the code must know about the specific policy, making the
> policy less amenable to adjustment as problems are discovered.  
> Wouldn't it be better for the domains to provide object managers?
 
> This would allow the STE policy to make statements about those new
> objects.  The code can be policy neutral by strictly following
the 
> decisions of the security server.  Wouldn't this make it easier
to 
> revoke policies and update them without having to change the code
and patch?
> 
> Dave
> 

> On 8/18/05, Reiner Sailer <sailer@xxxxxxxxxx>
wrote:
> 
> This patch: 
> 
> * adds a C-based security policy translation tool to Xen 
> (secpol_xml2bin) and removes the current Java 
> security policy translator (Java dependencies).  The C-based
tool 
> integrates into the Xen source tree build 
> and install (using gnome libxml2 for XML parsing). See install.txt.
> 
> * introduces security labels and related tools. Users can now use
> semantic-rich label names to put security-tags 
> on domains. See example.txt, policy.txt. 
> 
> * moves the security configuration (currently 
> ACM_USE_SECURITY_POLICY) from xen/Rules.mk 
> into a separate top-level Security.mk file  (it is needed by
the 
> tools/security and xen/acm). 
> 
> Both xen/acm and tools/security are built during the Xen build 
> process only if ACM_USE_SECURITY_POLICY 
> is not ACM_NULL_POLICY (which is the default setting). 
> 
> Comments welcome! 
> 
> Note: We are currently preparing a patch that introduces a new ACM
> command (getssid) to retrieve the security types 
> of a running domain. This command is enables domain-internal 
> enforcement functions based on the ACM security policy. 
> 
> Thanks 
> Reiner 
> 
> Signed-off-by Reiner Sailer <sailer@xxxxxxxxxx> 
> Signed-off by Stefan Berger <stefanb@xxxxxxxxxx> 
> Signed-off by Ray Valdez <rvaldez@xxxxxxxxxx> 
> 
> 
> _______________________________________________
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> Xense-devel@xxxxxxxxxxxxxxxxxxx 
> http://lists.xensource.com/xense-devel
> 
> 

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