[refpolicy] MCS Policy Constraints

[dwalsh@redhat.com (Daniel J Walsh)]

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On 04/10/2013 08:48 AM, Christopher J. PeBenito wrote:
> On 04/09/13 16:10, Douglas Brown wrote:
>> Hi all,
>> 
>> The MCS policy has only file, database and one network-related class
>> constraint. I'm sure this is deliberate by design, however I'd like to
>> know if there's any impediment to adding category domain separation for
>> all the classes in the MLS policy to the MCS policy and if I may submit a
>> patch to do so?
> 
> There isn't a problem adding constraints to the other object classes.
> However, the MCS policy is intended by design to be simple and only cover
> files and DB, so the patch would not be accepted.  If you're looking for
> comprehensive object class coverage with MCS, it might be sufficient to use
> the MLS policy but configure it with only 1 sensitivity (set MLS_SENS in
> build.conf).
> 
> 
This is the mcs file we currently have in Fedora.  We have lots of other
confinement.  We are using these for constraints on things like svirt_t for
containing virtual machines, openshift_t for containing OpenShift Users (gears)
As well as controlling sandbox desktop apps(sandbox_x_t) , containers for
secure services svirt_lxc_net_t.
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ifdef(`enable_mcs',`
default_range dir_file_class_set target low;

#
# Define sensitivities 
#
# MCS is single-sensitivity.

gen_sens(1)

#
# Define the categories
#
# Generate declarations

gen_cats(mcs_num_cats)

#
# Each MCS level specifies a sensitivity and zero or more categories which may
# be associated with that sensitivity.
#

gen_levels(1,mcs_num_cats)

#
# Define the MCS policy
#
# mlsconstrain class_set perm_set expression ;
#
# mlsvalidatetrans class_set expression ;
#
# expression : ( expression )
#	     | not expression
#	     | expression and expression
#	     | expression or expression
#	     | u1 op u2
#	     | r1 role_mls_op r2
#	     | t1 op t2
#	     | l1 role_mls_op l2
#	     | l1 role_mls_op h2
#	     | h1 role_mls_op l2
#	     | h1 role_mls_op h2
#	     | l1 role_mls_op h1
#	     | l2 role_mls_op h2
#	     | u1 op names
#	     | u2 op names
#	     | r1 op names
#	     | r2 op names
#	     | t1 op names
#	     | t2 op names
#	     | u3 op names (NOTE: this is only available for mlsvalidatetrans)
#	     | r3 op names (NOTE: this is only available for mlsvalidatetrans)
#	     | t3 op names (NOTE: this is only available for mlsvalidatetrans)
#
# op : == | !=
# role_mls_op : == | != | eq | dom | domby | incomp
#
# names : name | { name_list }
# name_list : name | name_list name
#

#
# MCS policy for the file classes
#
# Constrain file access so that the high range of the process dominates
# the high range of the file.  We use the high range of the process so
# that processes can always simply run at s0.
#
# Note:
#  - getattr on dirs/files is not constrained.
#  - /proc/pid operations are not constrained.

mlsconstrain file { read ioctl lock execute execute_no_trans }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain file { write setattr append unlink link rename }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain dir { search read ioctl lock }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain dir { write setattr append unlink link rename add_name remove_name }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain fifo_file { open }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain { lnk_file chr_file blk_file sock_file } { getattr read ioctl }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain { lnk_file chr_file blk_file sock_file } { write setattr }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

# New filesystem object labels must be dominated by the relabeling subject
# clearance, also the objects are single-level.
mlsconstrain file { create relabelto }
	((( h1 dom h2 ) and ( l2 eq h2 )) or
	 ( t1 != mcs_constrained_type ));

# new file labels must be dominated by the relabeling subject clearance
mlsconstrain { dir file lnk_file chr_file blk_file sock_file fifo_file } { relabelfrom }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain { file lnk_file fifo_file } { create relabelto }
	(( l2 eq h2 )  or ( t1 != mcs_constrained_type ));

mlsconstrain { dir file lnk_file chr_file blk_file sock_file fifo_file } { create relabelto }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain process { transition dyntransition }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain process { ptrace }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain process { sigkill sigstop }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain process { signal }
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

mlsconstrain { tcp_socket udp_socket rawip_socket } node_bind
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

#
# MCS policy for SELinux-enabled databases
#

# Any database object must be dominated by the relabeling subject
# clearance, also the objects are single-level.
mlsconstrain { db_database db_schema db_table db_sequence db_view db_procedure db_language db_column db_blob } { create relabelto }
	(( h1 dom h2 ) and ( l2 eq h2 ));

mlsconstrain { db_tuple } { insert relabelto }
	(( h1 dom h2 ) and ( l2 eq h2 ));

# Access control for any database objects based on MCS rules.
mlsconstrain db_database { drop getattr setattr relabelfrom access install_module load_module get_param set_param }
	( h1 dom h2 );

mlsconstrain db_schema { drop getattr setattr relabelfrom search }
	( h1 dom h2 );

mlsconstrain db_table { drop getattr setattr relabelfrom select update insert delete lock }
	( h1 dom h2 );

mlsconstrain db_column { drop getattr setattr relabelfrom select update insert }
	( h1 dom h2 );

mlsconstrain db_tuple { relabelfrom select update delete use }
	( h1 dom h2 );

mlsconstrain db_sequence { drop getattr setattr relabelfrom get_value next_value set_value }
	( h1 dom h2 );

mlsconstrain db_view { drop getattr setattr relabelfrom expand }
	( h1 dom h2 );

mlsconstrain db_procedure { drop getattr setattr relabelfrom execute install entrypoint }
	( h1 dom h2 );

mlsconstrain db_language { drop getattr setattr relabelfrom execute }
	( h1 dom h2 );

mlsconstrain db_blob { drop getattr setattr relabelfrom read write import export }
	( h1 dom h2 );

mlsconstrain { tcp_socket udp_socket rawip_socket } node_bind
	(( h1 dom h2 ) or ( t1 != mcs_constrained_type ));

# the node recvfrom/sendto ops, the recvfrom permission is a "write" operation
# because the subject in this particular case is the remote domain which is
# writing data out the network node which is acting as the object
mlsconstrain { node } { recvfrom sendto }
	(( l1 dom l2 ) or (t1 != mcs_constrained_type));

mlsconstrain { packet peer } { recv }
	(( l1 dom l2 ) or
	 ((t1 != mcs_constrained_type) and (t2 != mcs_constrained_type)));

# the netif ingress/egress ops, the ingress permission is a "write" operation
# because the subject in this particular case is the remote domain which is
# writing data out the network interface which is acting as the object
mlsconstrain { netif } { egress ingress }
	     	(( l1 dom l2 ) or (t1 != mcs_constrained_type));

') dnl end enable_mcs