From abb1ba6532c923106b459dbb3ba47d9c7038bc97 Mon Sep 17 00:00:00 2001
From: Joel Scherpelz <jscherpelz@google.com>
Date: Thu, 8 Jun 2017 13:59:41 +0900
Subject: [PATCH] SELinux policy for secure persistent netd storage
This is used to persist RFC 7217 stable secrets across device reboots.
First submit caused a merge conflict. This revision replaces netd_prop
with a more unique name netd_stable_secret_prop.
Test: as follows
- Manually tested that stable_secret is generated on first use and
persists until reset of user data partition (factory reset).
- Tested that "adb shell getprop" was denied access to
persist.netd.stable_secret after running "adb unroot".
Bug: 17613910
Change-Id: I0a609c724799a15b1926e62534c16810d34f2275
---
private/property_contexts | 1 +
public/netd.te | 9 +++++++++
public/property.te | 1 +
3 files changed, 11 insertions(+)
diff --git a/private/property_contexts b/private/property_contexts
index 23150343f..8eb2f28b2 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -50,6 +50,7 @@ persist.logd.logpersistd u:object_r:logpersistd_logging_prop:s0
logd.logpersistd u:object_r:logpersistd_logging_prop:s0
persist.log.tag u:object_r:log_tag_prop:s0
persist.mmc. u:object_r:mmc_prop:s0
+persist.netd.stable_secret u:object_r:netd_stable_secret_prop:s0
persist.sys. u:object_r:system_prop:s0
persist.sys.safemode u:object_r:safemode_prop:s0
ro.sys.safemode u:object_r:safemode_prop:s0
diff --git a/public/netd.te b/public/netd.te
index 35d9b7cee..d01d2f856 100644
--- a/public/netd.te
+++ b/public/netd.te
@@ -58,6 +58,7 @@ allow netd dnsmasq:process signal;
allow netd clatd:process signal;
set_prop(netd, ctl_mdnsd_prop)
+set_prop(netd, netd_stable_secret_prop)
# Allow netd to publish a binder service and make binder calls.
binder_use(netd)
@@ -104,3 +105,11 @@ neverallow netd { app_data_file system_data_file }:dir_file_class_set write;
neverallow { domain -system_server -dumpstate -netd } netd_service:service_manager find;
neverallow { domain -system_server -dumpstate } netd:binder call;
neverallow netd { domain -system_server -servicemanager userdebug_or_eng(`-su') }:binder call;
+
+# persist.netd.stable_secret contains RFC 7217 secret key which should never be
+# leaked to other processes. Make sure it never leaks.
+neverallow { domain -netd -init } netd_stable_secret_prop:file r_file_perms;
+
+# We want to ensure that no other process ever tries tampering with persist.netd.stable_secret,
+# the RFC 7217 secret key managed by netd. Doing so could compromise user privacy.
+neverallow { domain -netd -init } netd_stable_secret_prop:property_service set;
diff --git a/public/property.te b/public/property.te
index daac0fb5c..95efcaa78 100644
--- a/public/property.te
+++ b/public/property.te
@@ -30,6 +30,7 @@ type log_tag_prop, property_type, log_property_type;
type mmc_prop, property_type;
type net_dns_prop, property_type;
type net_radio_prop, property_type, core_property_type;
+type netd_stable_secret_prop, property_type;
type nfc_prop, property_type, core_property_type;
type overlay_prop, property_type;
type pan_result_prop, property_type, core_property_type;
--
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