selinux-policy/refpolicy/policy/modules/admin/su.if

## <summary>Run shells with substitute user and group</summary>

#######################################
## <summary>
##	The per user domain template for the su module.
## </summary>
## <desc>
##	<p>
##	This template creates a derived domain which is allowed
##	to change the linux user id, to run shells as a different
##	user.
##	</p>
##	<p>
##	This template is invoked automatically for each user, and
##	generally does not need to be invoked directly
##	by policy writers.
##	</p>
## </desc>
## <param name="userdomain_prefix">
##	The prefix of the user domain (e.g., user
##	is the prefix for user_t).
## </param>
## <param name="user_domain">
##	The type of the user domain.
## </param>
## <param name="user_role">
##	The role associated with the user domain.
## </param>
#
template(`su_per_userdomain_template',`
	# in optional since loadable modules do not natively
	# support per-userdomain templates yet.
	optional_policy(`su.te',`
		gen_require(`
			type su_exec_t;
		')

		type $1_su_t;
		domain_entry_file($1_su_t,su_exec_t)
		domain_type($1_su_t)
		domain_role_change_exempt($1_su_t)
		domain_subj_id_change_exempt($1_su_t)
		domain_obj_id_change_exempt($1_su_t)
		domain_wide_inherit_fd($1_su_t)
		role $3 types $1_su_t;

		allow $2 $1_su_t:process signal;

		allow $1_su_t self:capability { audit_control setuid setgid net_bind_service chown dac_override fowner sys_nice sys_resource };
		dontaudit $1_su_t self:capability sys_tty_config;
		allow $1_su_t self:process { setexec setsched setrlimit };
		allow $1_su_t self:fifo_file rw_file_perms;
		allow $1_su_t self:netlink_audit_socket { nlmsg_relay create_netlink_socket_perms };

		# Transition from the user domain to this domain.
		domain_auto_trans($2, su_exec_t, $1_su_t)
		allow $2 $1_su_t:fd use;
		allow $1_su_t $2:fd use;
		allow $1_su_t $2:fifo_file rw_file_perms;
		allow $1_su_t $2:process sigchld;

		# By default, revert to the calling domain when a shell is executed.
		corecmd_shell_domtrans($1_su_t,$2)
		allow $2 $1_su_t:fd use;
		allow $1_su_t $2:fd use;
		allow $1_su_t $2:fifo_file rw_file_perms;
		allow $1_su_t $2:process sigchld;

		kernel_read_system_state($1_su_t)
		kernel_read_kernel_sysctl($1_su_t)

		# for SSP
		dev_read_urand($1_su_t)

		fs_search_auto_mountpoints($1_su_t)

		selinux_get_fs_mount($1_su_t)
		selinux_validate_context($1_su_t)
		selinux_compute_access_vector($1_su_t)
		selinux_compute_create_context($1_su_t)
		selinux_compute_relabel_context($1_su_t)
		selinux_compute_user_contexts($1_su_t)

		# Relabel ttys and ptys.
		term_relabel_all_user_ttys($1_su_t)
		term_relabel_all_user_ptys($1_su_t)
		# Close and re-open ttys and ptys to get the fd into the correct domain.
		term_use_all_user_ttys($1_su_t)
		term_use_all_user_ptys($1_su_t)

		auth_domtrans_user_chk_passwd($1_su_t,$1)
		auth_dontaudit_read_shadow($1_su_t)

		domain_wide_inherit_fd($1_su_t)

		files_read_etc_files($1_su_t)
		files_search_var_lib($1_su_t)

		init_dontaudit_use_fd($1_su_t)
		# Write to utmp.
		init_rw_script_pid($1_su_t)

		libs_use_ld_so($1_su_t)
		libs_use_shared_libs($1_su_t)

		logging_send_syslog_msg($1_su_t)

		miscfiles_read_localization($1_su_t)

		seutil_read_config($1_su_t)
		seutil_read_default_contexts($1_su_t)

		userdom_use_user_terminals($1,$1_su_t)

		if(secure_mode)
		{
			# Only allow transitions to unprivileged user domains.
			userdom_spec_domtrans_unpriv_users($1_su_t)
		} else {
			# Allow transitions to all user domains
			userdom_spec_domtrans_all_users($1_su_t)
		}

		if (use_nfs_home_dirs) {
			fs_search_nfs($1_su_t)
		}

		if (use_samba_home_dirs) {
			fs_search_cifs($1_su_t)
		}

		optional_policy(`crond.te',`
			cron_read_pipe($1_su_t)
		')

		optional_policy(`kerberos.te',`
			kerberos_use($1_su_t)
		')

		optional_policy(`nis.te',`
			nis_use_ypbind($1_su_t)
		')

		optional_policy(`nscd.te',`
			nscd_use_socket($1_su_t)
		')

		ifdef(`TODO',`

		ifdef(`support_polyinstantiation', `
		mls_file_read_up($1_su_t)
		mls_file_write_down($1_su_t)
		mls_file_upgrade($1_su_t)
		mls_file_downgrade($1_su_t)
		mls_process_set_level($1_su_t)

		# Su can polyinstantiate
		polyinstantiater($1_su_t)
		# Su has to unmount polyinstantiated directories (like home)
		# that should not be polyinstantiated under the new user
		allow $1_su_t fs_t:filesystem unmount;
		# Su needs additional permission to mount over a previous mount
		allow $1_su_t polymember:dir mounton;
		')

		# Caused by su - init scripts
		dontaudit $1_su_t initrc_devpts_t:chr_file { getattr ioctl };

		# Inherit and use descriptors from gnome-pty-helper.
		ifdef(`gnome-pty-helper.te', `allow $1_su_t $1_gph_t:fd use;')

		allow $1_su_t { home_root_t $1_home_dir_t }:dir search;
		allow $1_su_t $1_home_t:file create_file_perms;

		ifdef(`user_canbe_sysadm', `
		allow $1_su_t home_dir_type:dir { search write };
		', `
		dontaudit $1_su_t home_dir_type:dir { search write };
		')

		# Modify .Xauthority file (via xauth program).
		ifdef(`xauth.te', `
		file_type_auto_trans($1_su_t, staff_home_dir_t, staff_xauth_home_t, file)
		file_type_auto_trans($1_su_t, user_home_dir_t, user_xauth_home_t, file)
		file_type_auto_trans($1_su_t, sysadm_home_dir_t, sysadm_xauth_home_t, file)
		domain_auto_trans($1_su_t, xauth_exec_t, $1_xauth_t)
		')

		ifdef(`cyrus.te', `
		allow $1_su_t cyrus_var_lib_t:dir search;
		')
		ifdef(`ssh.te', `
		# Access sshd cookie files.
		allow $1_su_t sshd_tmp_t:file rw_file_perms;
		file_type_auto_trans($1_su_t, sshd_tmp_t, $1_tmp_t)
		')
		') dnl end TODO
	')
')

#######################################
## <summary>
##	Execute su in the caller domain.
## </summary>
## <param name="domain">
##	Domain allowed access.
## </param>
#
interface(`su_exec',`
	gen_require(`
		type su_exec_t;
	')

	can_exec($1,su_exec_t)
')