From b362474374afc402f65695252d30a008326c0eba Mon Sep 17 00:00:00 2001
From: Nick Kralevich <nnk@google.com>
Date: Wed, 12 Dec 2018 09:06:39 -0800
Subject: [PATCH] remove app_data_file execute
Remove the ability for applications to dlopen() executable code from
their home directory for newer API versions. API versions <= 28 are
uneffected by this change.
Bug: 112357170
Test: cts-tradefed run cts -m CtsRenderscriptTestCases
Change-Id: I1d7f3a1015d54b8610d1c561f38a1a3c2bcf79e4
---
private/app_neverallows.te | 13 ++++++++++++-
private/ephemeral_app.te | 2 +-
private/runas_app.te | 7 ++++---
private/untrusted_app_25.te | 8 ++++----
private/untrusted_app_27.te | 6 +++---
private/untrusted_app_all.te | 2 +-
6 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/private/app_neverallows.te b/private/app_neverallows.te
index 6ebbd436a..10b0b3bd0 100644
--- a/private/app_neverallows.te
+++ b/private/app_neverallows.te
@@ -47,7 +47,7 @@ neverallow { all_untrusted_apps -untrusted_app_25 } net_dns_prop:file read;
neverallow all_untrusted_apps rs_data_file:file
{ append create link relabelfrom relabelto rename setattr write };
-# Block calling execve() on files in an apps home directory.
+# Block calling execve() in app /data/data files.
# This is a W^X violation (loading executable code from a writable
# home directory). For compatibility, allow for targetApi <= 28.
# b/112357170
@@ -58,6 +58,17 @@ neverallow {
-runas_app
} { app_data_file privapp_data_file }:file execute_no_trans;
+# Block calling dlopen() in app /data/data files.
+# This is a W^X violation (loading executable code from a writable
+# home directory). For compatibility, allow for targetApi <= 28.
+# b/112357170
+neverallow {
+ all_untrusted_apps
+ -untrusted_app_25
+ -untrusted_app_27
+ -runas_app
+} app_data_file:file execute;
+
# Do not allow untrusted apps to invoke dex2oat. This was historically required
# by ART for compiling secondary dex files but has been removed in Q.
# Exempt legacy apps (targetApi<=28) for compatibility.
diff --git a/private/ephemeral_app.te b/private/ephemeral_app.te
index 4935f3340..92fd32546 100644
--- a/private/ephemeral_app.te
+++ b/private/ephemeral_app.te
@@ -22,7 +22,7 @@ allow ephemeral_app { sdcard_type media_rw_data_file }:file {read write getattr
# Some apps ship with shared libraries and binaries that they write out
# to their sandbox directory and then execute.
allow ephemeral_app privapp_data_file:file { r_file_perms execute };
-allow ephemeral_app app_data_file:file { r_file_perms execute };
+allow ephemeral_app app_data_file:file r_file_perms;
# Allow the renderscript compiler to be run.
domain_auto_trans(ephemeral_app, rs_exec, rs)
diff --git a/private/runas_app.te b/private/runas_app.te
index b976b9187..00baa83fa 100644
--- a/private/runas_app.te
+++ b/private/runas_app.te
@@ -6,6 +6,7 @@ untrusted_app_domain(runas_app)
net_domain(runas_app)
bluetooth_domain(runas_app)
-# The ability to call exec() on files in the apps home directories
-# when using run-as on a debuggable app. Needed by simpleperf.
-allow runas_app app_data_file:file execute_no_trans;
+# The ability to call exec() or dlopen() on app /data/data
+# files when using run-as on a debuggable app.
+# Needed by simpleperf.
+allow runas_app app_data_file:file { execute_no_trans execute };
diff --git a/private/untrusted_app_25.te b/private/untrusted_app_25.te
index 7c266a524..8825e2e78 100644
--- a/private/untrusted_app_25.te
+++ b/private/untrusted_app_25.te
@@ -45,10 +45,10 @@ allow untrusted_app_25 proc_tty_drivers:file r_file_perms;
# https://android.googlesource.com/platform/bionic/+/master/android-changes-for-ndk-developers.md#text-relocations-enforced-for-api-level-23
allow untrusted_app_25 { apk_data_file app_data_file asec_public_file }:file execmod;
-# The ability to call exec() on files in the apps home directories
-# for targetApi<=25. This is also allowed for targetAPIs 26, 27,
-# and 28 in untrusted_app_27.te.
-allow untrusted_app_25 app_data_file:file execute_no_trans;
+# The ability to call exec() or dlopen() on files in the apps home
+# directories for targetApi<=25. This is also allowed for targetAPIs 26,
+# 27, and 28 in untrusted_app_27.te.
+allow untrusted_app_25 app_data_file:file { execute execute_no_trans };
# The ability to invoke dex2oat. Historically required by ART, now only
# allowed for targetApi<=28 for compat reasons.
diff --git a/private/untrusted_app_27.te b/private/untrusted_app_27.te
index b8fd22eb4..fab6acc36 100644
--- a/private/untrusted_app_27.te
+++ b/private/untrusted_app_27.te
@@ -27,9 +27,9 @@ untrusted_app_domain(untrusted_app_27)
net_domain(untrusted_app_27)
bluetooth_domain(untrusted_app_27)
-# The ability to call exec() on files in the apps home directories
-# for targetApi 26, 27, and 28.
-allow untrusted_app_27 app_data_file:file execute_no_trans;
+# The ability to call exec() or dlopen() on files in the apps home
+# directories for targetApi 26, 27, and 28.
+allow untrusted_app_27 app_data_file:file { execute execute_no_trans };
# The ability to invoke dex2oat. Historically required by ART, now only
# allowed for targetApi<=28 for compat reasons.
diff --git a/private/untrusted_app_all.te b/private/untrusted_app_all.te
index aebb7118a..2c81ebdae 100644
--- a/private/untrusted_app_all.te
+++ b/private/untrusted_app_all.te
@@ -23,7 +23,7 @@
# Some apps ship with shared libraries and binaries that they write out
# to their sandbox directory and then execute.
allow untrusted_app_all privapp_data_file:file { r_file_perms execute };
-allow untrusted_app_all app_data_file:file { r_file_perms execute };
+allow untrusted_app_all app_data_file:file r_file_perms;
# Allow loading and deleting renderscript created shared libraries
# within an application home directory.
--
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