From 11b2f2af503b54850730dbda672a167bb7f0ac38 Mon Sep 17 00:00:00 2001
From: Nicolas Iooss <nicolas.iooss@m4x.org>
Date: Tue, 5 Jan 2016 18:00:59 +0100
Subject: [PATCH] Add an interface for systemd daemons to configure logging

Many systemd daemons use log_parse_environment() and log_open() to
configure the way they log messages.  These internal systemd functions
requires a bunch of permissions like reading /proc/cmdline and
/proc/1/environ to run.  Create an interface to ease allowing these
accesses.
---
 policy/modules/system/systemd.if | 42 ++++++++++++++++++++++++++++++++++++++++
 policy/modules/system/systemd.te |  6 ++++--
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/policy/modules/system/systemd.if b/policy/modules/system/systemd.if
index 3cd667000098..d24f9cec82f1 100644
--- a/policy/modules/system/systemd.if
+++ b/policy/modules/system/systemd.if
@@ -171,3 +171,45 @@ interface(`systemd_start_power_units',`
 
 	allow $1 power_unit_t:service start;
 ')
+
+########################################
+## <summary>
+##	Allow specified domain to parse environment to set up logging.
+## </summary>
+## <desc>
+##	<p>
+##	Many systemd daemons set-up their logging by calling
+##	functions log_parse_environment and log_open, which
+##	source code is available on
+##	https://github.com/systemd/systemd/blob/v227/src/basic/log.c
+##	</p>
+##	<p>
+##	Function log_parse_environment calls parse_proc_cmdline,
+##	which reads /proc/cmdline and calls detect_container,
+##	which reads /proc/1/environ.
+##	</p>
+##	<p>
+##	Function log_open may call log_open_syslog, which calls
+##	create_log_socket, which calls fd_inc_sndbuf, which does
+##	setsockopt(fd, SOL_SOCKET, SO_SNDBUFFORCE, ...), which
+##	requires CAP_NET_ADMIN.  Nevertheless if CAP_NET_ADMIN
+##	access is denied, fd_inc_sndbuf falls back to using
+##	SO_SNDBUF option, which does not require any capability.
+##	</p>
+## </desc>
+## <param name="domain">
+##	<summary>
+##	Domain allowed access.
+##	</summary>
+## </param>
+#
+interface(`systemd_parse_log_environment',`
+	# Allow to read /proc/1/environ
+	init_read_state($1)
+	# Allow to read /proc/cmdline
+	kernel_read_system_state($1)
+	# Do not audit setsockopt(fd, SOL_SOCKET, SO_SNDBUFFORCE, ...) failure
+	dontaudit $1 self:capability net_admin;
+
+	logging_send_syslog_msg($1)
+')
diff --git a/policy/modules/system/systemd.te b/policy/modules/system/systemd.te
index fdb9fefc2ec2..87e678d4baec 100644
--- a/policy/modules/system/systemd.te
+++ b/policy/modules/system/systemd.te
@@ -120,7 +120,7 @@ kernel_domtrans_to(systemd_cgroups_t, systemd_cgroups_exec_t)
 
 init_stream_connect(systemd_cgroups_t)
 
-logging_send_syslog_msg(systemd_cgroups_t)
+systemd_parse_log_environment(systemd_cgroups_t)
 
 kernel_dgram_send(systemd_cgroups_t)
 
@@ -147,7 +147,7 @@ optional_policy(`
 
 files_read_etc_files(systemd_hostnamed_t)
 
-logging_send_syslog_msg(systemd_hostnamed_t)
+systemd_parse_log_environment(systemd_hostnamed_t)
 
 seutil_read_file_contexts(systemd_hostnamed_t)
 
@@ -254,6 +254,8 @@ logging_send_syslog_msg(systemd_tmpfiles_t)
 
 seutil_read_file_contexts(systemd_tmpfiles_t)
 
+systemd_parse_log_environment(systemd_tmpfiles_t)
+
 tunable_policy(`systemd_tmpfiles_manage_all',`
 	# systemd-tmpfiles can be configured to manage anything.
 	# have a last-resort option for users to do this.
-- 
2.6.4