Add libhwminijail for sandboxing with seccomp filters

This is a partial cherry-pick of the internal change, including just
libhwminijail. The user does not exist in AOSP yet.

Bug: 36453956
Test: mmma hardware/interface/minijail
Merged-In: Iab014ff357b7329085a5e18a92f51838d2c72371
Change-Id: I46b030efba25aac3c09cef9bfb782ecdc7187e70

minijail/Android.mk

@@ -0,0 +1,14 @@
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := libhwminijail
+LOCAL_PROPRIETARY_MODULE := true
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
+LOCAL_SRC_FILES := HardwareMinijail.cpp
+
+LOCAL_SHARED_LIBRARIES := \
+    libbase \
+    libminijail_vendor
+
+include $(BUILD_SHARED_LIBRARY)

minijail/HardwareMinijail.cpp

@@ -0,0 +1,45 @@
+//
+// 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.
+//
+
+#include <android-base/logging.h>
+#include <libminijail.h>
+
+#include <hwminijail/HardwareMinijail.h>
+
+namespace android {
+namespace hardware {
+
+void SetupMinijail(const std::string& seccomp_policy_path) {
+    if (access(seccomp_policy_path.c_str(), R_OK) == -1) {
+        LOG(WARNING) << "Could not find seccomp policy file at: " << seccomp_policy_path;
+        return;
+    }
+
+    struct minijail* jail = minijail_new();
+    if (jail == NULL) {
+        LOG(FATAL) << "Failed to create minijail.";
+    }
+
+    minijail_no_new_privs(jail);
+    minijail_log_seccomp_filter_failures(jail);
+    minijail_use_seccomp_filter(jail);
+    minijail_parse_seccomp_filters(jail, seccomp_policy_path.c_str());
+    minijail_enter(jail);
+    minijail_destroy(jail);
+}
+
+}  // namespace hardware
+}  // namespace android

minijail/include/hwminijail/HardwareMinijail.h

@@ -0,0 +1,30 @@
+//
+// 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.
+//
+
+#ifndef ANDROID_HARDWARE_CONFIGSTORE_MINIJAIL_H
+#define ANDROID_HARDWARE_CONFIGSTORE_MINIJAIL_H
+
+#include <string>
+
+namespace android {
+namespace hardware {
+
+void SetupMinijail(const std::string& seccomp_policy_path);
+
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_CONFIGSTORE_UTILS_H