configstore: sandbox with seccomp filter

Configstore HAL is accessible to third party apps and thus requires
a tight sandbox that reflects the limited system access this HAL
needs.

We use two primary mechanisms to sandbox configstore, selinux and
seccomp, with the goal of restricting its access to userspace and
the kernel. The addition of a seccomp filter is primarily aimed
at reducing the kernel's attack surface that is reachable by
configstore HAL.

Seccomp filters are architecture dependent, so filters need to be
added for each architecture. This change adds a seccomp filter for
arm64 and issues a non-fatal runtime warning for other architectures
which still require a seccomp filter.

Bug: 36453956
Test: boot Marlin and Angler. Verify that configstore is not aborting
    due to seccomp violations.
Test: "cat proc/<configstore pid>/status | grep seccomp " returns:
    seccomp: 2
    Which indicates that configstore is using seccomp-bpf.

Change-Id: Iab014ff357b7329085a5e18a92f51838d2c72371
(cherry picked from commit ed95043d6433c5900984f24dbb101bba78109775)

3 files changed, 56 insertions, 0 deletions

diff --git a/configstore/1.1/default/Android.mk b/configstore/1.1/default/Android.mk
index ac3d8b039d..58b67c1525 100644
--- a/configstore/1.1/default/Android.mk
+++ b/configstore/1.1/default/Android.mk
@@ -3,6 +3,7 @@ LOCAL_PATH := $(call my-dir)
 ################################################################################
 include $(CLEAR_VARS)
 LOCAL_MODULE := android.hardware.configstore@1.1-service
+LOCAL_REQUIRED_MODULES_arm64 := configstore@1.1.policy
 LOCAL_PROPRIETARY_MODULE := true
 LOCAL_MODULE_CLASS := EXECUTABLES
 LOCAL_MODULE_RELATIVE_PATH := hw
@@ -17,7 +18,18 @@ LOCAL_SHARED_LIBRARIES := \
     libhidlbase \
     libhidltransport \
     libbase \
+    libhwminijail \
     liblog \
     libutils \
 
 include $(BUILD_EXECUTABLE)
+
+# seccomp filter for configstore
+ifeq ($(TARGET_ARCH), $(filter $(TARGET_ARCH), arm64))
+include $(CLEAR_VARS)
+LOCAL_MODULE := configstore@1.1.policy
+LOCAL_MODULE_CLASS := ETC
+LOCAL_MODULE_PATH := $(TARGET_OUT_VENDOR)/etc/seccomp_policy
+LOCAL_SRC_FILES := seccomp_policy/configstore@1.1-$(TARGET_ARCH).policy
+include $(BUILD_PREBUILT)
+endif
diff --git a/configstore/1.1/default/seccomp_policy/configstore@1.1-arm64.policy b/configstore/1.1/default/seccomp_policy/configstore@1.1-arm64.policy
new file mode 100644
index 0000000000..8c901eb8de
--- /dev/null
+++ b/configstore/1.1/default/seccomp_policy/configstore@1.1-arm64.policy
@@ -0,0 +1,40 @@
+# Copyright (C) 2017 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+futex: 1
+# ioctl: arg1 == BINDER_WRITE_READ
+ioctl: arg1 == 0xc0306201
+ioctl: 1
+# prctl: arg0 == PR_SET_NAME || arg0 == PR_SET_VMA || arg0 == PR_SET_TIMERSLACK
+prctl: arg0 == 15 || arg0 == 0x53564d41 || arg0 == 29
+openat: 1
+mmap: 1
+mprotect: 1
+close: 1
+getuid: 1
+read: 1
+faccessat: 1
+write: 1
+fstat: 1
+clone: 1
+munmap: 1
+lseek: 1
+sigaltstack: 1
+writev: 1
+setpriority: 1
+restart_syscall: 1
+exit: 1
+exit_group: 1
+rt_sigreturn: 1
+getrlimit: 1
diff --git a/configstore/1.1/default/service.cpp b/configstore/1.1/default/service.cpp
index 52db025107..535e0cdd96 100644
--- a/configstore/1.1/default/service.cpp
+++ b/configstore/1.1/default/service.cpp
@@ -18,6 +18,7 @@
 
 #include <android/hardware/configstore/1.1/ISurfaceFlingerConfigs.h>
 #include <hidl/HidlTransportSupport.h>
+#include <hwminijail/HardwareMinijail.h>
 
 #include "SurfaceFlingerConfigs.h"
 
@@ -25,6 +26,7 @@ using android::hardware::configureRpcThreadpool;
 using android::hardware::joinRpcThreadpool;
 using android::hardware::configstore::V1_1::ISurfaceFlingerConfigs;
 using android::hardware::configstore::V1_1::implementation::SurfaceFlingerConfigs;
+using android::hardware::SetupMinijail;
 using android::sp;
 using android::status_t;
 using android::OK;
@@ -32,6 +34,8 @@ using android::OK;
 int main() {
     configureRpcThreadpool(10, true);
 
+    SetupMinijail("/vendor/etc/seccomp_policy/configstore@1.1.policy");
+
     sp<ISurfaceFlingerConfigs> surfaceFlingerConfigs = new SurfaceFlingerConfigs;
     status_t status = surfaceFlingerConfigs->registerAsService();
     LOG_ALWAYS_FATAL_IF(status != OK, "Could not register ISurfaceFlingerConfigs");