selinux-policy/strict/constraints

#
# Define m4 macros for the constraints
#

#
# Define the constraints
#
# constrain class_set perm_set expression ;
#
# validatetrans 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 validatetrans)
#	     | r3 op names (NOTE: this is only available for validatetrans)
#	     | t3 op names (NOTE: this is only available for validatetrans)
#
# op : == | !=
# role_mls_op : == | != | eq | dom | domby | incomp
#
# names : name | { name_list }
# name_list : name | name_list name#
#

#
# Restrict the ability to transition to other users
# or roles to a few privileged types.
#

constrain process transition
	( u1 == u2 or ( t1 == privuser 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)')
	 or (t1 == priv_system_role and u2 == system_u )
        );

constrain process transition 
	( r1 == r2 or ( t1 == privrole 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 )')
')
	 or (t1 == priv_system_role and r2 == system_r )
        );

constrain process dyntransition
	( u1 == u2 and r1 == r2);

#
# Restrict the ability to label objects with other
# user identities to a few privileged types.
#

constrain dir_file_class_set { create relabelto relabelfrom } 
	( u1 == u2 or t1 == privowner );

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