init: Refactor selinux.h/cpp

This change factors out functions that handle selabels from
selinux.h/cpp into selabel.h/cpp.  This allows util.cpp to be used by
the upcoming native zygote without a bunch of define flags that are
required for selinux.cpp.

Bug: 133443795
Test: Build and boot cuttlefish.
Change-Id: Ie238a96c6407c6698a605dd8803c1727abfaae7b

init/Android.bp

@@ -124,6 +124,7 @@ cc_library_static {
         "reboot.cpp",
         "reboot_utils.cpp",
         "security.cpp",
+        "selabel.cpp",
         "selinux.cpp",
         "service.cpp",
         "sigchld_handler.cpp",

init/Android.mk

@@ -52,6 +52,7 @@ LOCAL_SRC_FILES := \
     first_stage_mount.cpp \
     mount_namespace.cpp \
     reboot_utils.cpp \
+    selabel.cpp \
     selinux.cpp \
     switch_root.cpp \
     uevent_listener.cpp \

init/builtins.cpp

@@ -70,6 +70,7 @@
 #include "property_service.h"
 #include "reboot.h"
 #include "rlimit_parser.h"
+#include "selabel.h"
 #include "selinux.h"
 #include "service.h"
 #include "subcontext.h"

init/devices.cpp

@@ -36,7 +36,7 @@
 #include <selinux/android.h>
 #include <selinux/selinux.h>
 
-#include "selinux.h"
+#include "selabel.h"
 #include "util.h"
 
 #ifdef _INIT_INIT_H

init/init.cpp

@@ -65,6 +65,7 @@
 #include "reboot.h"
 #include "reboot_utils.h"
 #include "security.h"
+#include "selabel.h"
 #include "selinux.h"
 #include "sigchld_handler.h"
 #include "util.h"

init/selabel.cpp

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2019 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 "selabel.h"
+
+#include <selinux/android.h>
+
+namespace android {
+namespace init {
+
+namespace {
+
+selabel_handle* sehandle = nullptr;
+}
+
+// selinux_android_file_context_handle() takes on the order of 10+ms to run, so we want to cache
+// its value.  selinux_android_restorecon() also needs an sehandle for file context look up.  It
+// will create and store its own copy, but selinux_android_set_sehandle() can be used to provide
+// one, thus eliminating an extra call to selinux_android_file_context_handle().
+void SelabelInitialize() {
+    sehandle = selinux_android_file_context_handle();
+    selinux_android_set_sehandle(sehandle);
+}
+
+// A C++ wrapper around selabel_lookup() using the cached sehandle.
+// If sehandle is null, this returns success with an empty context.
+bool SelabelLookupFileContext(const std::string& key, int type, std::string* result) {
+    result->clear();
+
+    if (!sehandle) return true;
+
+    char* context;
+    if (selabel_lookup(sehandle, &context, key.c_str(), type) != 0) {
+        return false;
+    }
+    *result = context;
+    free(context);
+    return true;
+}
+
+// A C++ wrapper around selabel_lookup_best_match() using the cached sehandle.
+// If sehandle is null, this returns success with an empty context.
+bool SelabelLookupFileContextBestMatch(const std::string& key,
+                                       const std::vector<std::string>& aliases, int type,
+                                       std::string* result) {
+    result->clear();
+
+    if (!sehandle) return true;
+
+    std::vector<const char*> c_aliases;
+    for (const auto& alias : aliases) {
+        c_aliases.emplace_back(alias.c_str());
+    }
+    c_aliases.emplace_back(nullptr);
+
+    char* context;
+    if (selabel_lookup_best_match(sehandle, &context, key.c_str(), &c_aliases[0], type) != 0) {
+        return false;
+    }
+    *result = context;
+    free(context);
+    return true;
+}
+
+}  // namespace init
+}  // namespace android

init/selabel.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+#include <string>
+#include <vector>
+
+namespace android {
+namespace init {
+
+void SelabelInitialize();
+bool SelabelLookupFileContext(const std::string& key, int type, std::string* result);
+bool SelabelLookupFileContextBestMatch(const std::string& key,
+                                       const std::vector<std::string>& aliases, int type,
+                                       std::string* result);
+
+}  // namespace init
+}  // namespace android

init/selinux.cpp

@@ -79,8 +79,6 @@ namespace init {
 
 namespace {
 
-selabel_handle* sehandle = nullptr;
-
 enum EnforcingStatus { SELINUX_PERMISSIVE, SELINUX_ENFORCING };
 
 EnforcingStatus StatusFromCmdline() {
@@ -554,54 +552,5 @@ int SetupSelinux(char** argv) {
     return 1;
 }
 
-// selinux_android_file_context_handle() takes on the order of 10+ms to run, so we want to cache
-// its value.  selinux_android_restorecon() also needs an sehandle for file context look up.  It
-// will create and store its own copy, but selinux_android_set_sehandle() can be used to provide
-// one, thus eliminating an extra call to selinux_android_file_context_handle().
-void SelabelInitialize() {
-    sehandle = selinux_android_file_context_handle();
-    selinux_android_set_sehandle(sehandle);
-}
-
-// A C++ wrapper around selabel_lookup() using the cached sehandle.
-// If sehandle is null, this returns success with an empty context.
-bool SelabelLookupFileContext(const std::string& key, int type, std::string* result) {
-    result->clear();
-
-    if (!sehandle) return true;
-
-    char* context;
-    if (selabel_lookup(sehandle, &context, key.c_str(), type) != 0) {
-        return false;
-    }
-    *result = context;
-    free(context);
-    return true;
-}
-
-// A C++ wrapper around selabel_lookup_best_match() using the cached sehandle.
-// If sehandle is null, this returns success with an empty context.
-bool SelabelLookupFileContextBestMatch(const std::string& key,
-                                       const std::vector<std::string>& aliases, int type,
-                                       std::string* result) {
-    result->clear();
-
-    if (!sehandle) return true;
-
-    std::vector<const char*> c_aliases;
-    for (const auto& alias : aliases) {
-        c_aliases.emplace_back(alias.c_str());
-    }
-    c_aliases.emplace_back(nullptr);
-
-    char* context;
-    if (selabel_lookup_best_match(sehandle, &context, key.c_str(), &c_aliases[0], type) != 0) {
-        return false;
-    }
-    *result = context;
-    free(context);
-    return true;
-}
-
 }  // namespace init
 }  // namespace android

init/selinux.h

@@ -14,11 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef _INIT_SELINUX_H
-#define _INIT_SELINUX_H
-
-#include <string>
-#include <vector>
+#pragma once
 
 namespace android {
 namespace init {
@@ -29,15 +25,7 @@ void SelinuxRestoreContext();
 void SelinuxSetupKernelLogging();
 int SelinuxGetVendorAndroidVersion();
 
-void SelabelInitialize();
-bool SelabelLookupFileContext(const std::string& key, int type, std::string* result);
-bool SelabelLookupFileContextBestMatch(const std::string& key,
-                                       const std::vector<std::string>& aliases, int type,
-                                       std::string* result);
-
 static constexpr char kEnvSelinuxStartedAt[] = "SELINUX_STARTED_AT";
 
 }  // namespace init
 }  // namespace android
-
-#endif

init/subcontext.cpp

@@ -32,6 +32,7 @@
 #if defined(__ANDROID__)
 #include <android/api-level.h>
 #include "property_service.h"
+#include "selabel.h"
 #include "selinux.h"
 #else
 #include "host_init_stubs.h"

init/ueventd.cpp

@@ -37,6 +37,7 @@
 #include "devices.h"
 #include "firmware_handler.h"
 #include "modalias_handler.h"
+#include "selabel.h"
 #include "selinux.h"
 #include "uevent_handler.h"
 #include "uevent_listener.h"

init/util.cpp

@@ -41,7 +41,7 @@
 
 #if defined(__ANDROID__)
 #include "reboot_utils.h"
-#include "selinux.h"
+#include "selabel.h"
 #else
 #include "host_init_stubs.h"
 #endif