selinux-policy/refpolicy/policy/constraints

#
# Define m4 macros for the constraints
#

#
# Define the constraints
#
# constrain class_set perm_set expression ;
#
# expression : ( expression ) 
#	     | not expression
#	     | expression and expression
#	     | expression or expression
#	     | u1 op u2
#	     | r1 role_op r2
#	     | t1 op t2
#	     | u1 op names
#	     | u2 op names
#	     | r1 op names
#	     | r2 op names
#	     | t1 op names
#	     | t2 op names
#
# op : == | != 
# role_op : == | != | eq | dom | domby | incomp
#
# names : name | { name_list }
# name_list : name | name_list name		
#

#
# SELinux process identity change constraint:
#
constrain process transition
	( u1 == u2 or ( t1 == can_change_process_identity and t2 == userdomain )
ifdef(`crond.te', `
         or (t1 == crond_t and (t2 == user_crond_domain or u2 == system_u))
')
ifdef(`userhelper.te', 
	`or (t1 == userhelperdomain)
')
ifdef(`TODO',`
	 or (t1 == priv_system_role and u2 == system_u )
') dnl end TODO
        );

#
# SELinux process role change constraint:
#
constrain process transition 
	( r1 == r2 or ( t1 == can_change_process_role and t2 == userdomain )
ifdef(`crond.te', `
         or (t1 == crond_t and t2 == user_crond_domain)
')
ifdef(`userhelper.te', 
	`or (t1 == userhelperdomain)
')
ifdef(`postfix.te', `
ifdef(`direct_sysadm_daemon',
	`or (t1 == sysadm_mail_t and t2 == system_mail_t and r2 == system_r )
')
')
ifdef(`TODO',`
	 or (t1 == priv_system_role and r2 == system_r )
') dnl end TODO
        );

#
# SELinux dynamic transition constraint:
#
constrain process dyntransition
	( u1 == u2 and r1 == r2);

#
# SElinux object identity change constraint:
#
constrain dir_file_class_set { create relabelto relabelfrom } 
	( u1 == u2 or t1 == can_change_object_identity );

constrain socket_class_set { create relabelto relabelfrom } 
	( u1 == u2 or t1 == can_change_object_identity );