Reland "Have property_service create a serialized property_contexts file" (2ae2f606) · Commits · e / os / android_system_core

init/Android.bp

+3 −0

Original line number	Diff line number	Diff line
		@@ -95,6 +95,8 @@ cc_library_static {
		"libprocessgroup",
		"libfs_mgr",
		"libprotobuf-cpp-lite",
		"libpropertyinfoserializer",
		"libpropertyinfoparser",
		],
		include_dirs: [
		"system/core/mkbootimg",
		@@ -193,6 +195,7 @@ cc_test {
		"libselinux",
		"libcrypto",
		"libprotobuf-cpp-lite",
		"libpropertyinfoparser",
		],
		}

init/Android.mk

+2 −0

Original line number	Diff line number	Diff line
		@@ -84,6 +84,8 @@ LOCAL_STATIC_LIBRARIES := \
		libavb \
		libkeyutils \
		libprotobuf-cpp-lite \
		libpropertyinfoserializer \
		libpropertyinfoparser \

		LOCAL_REQUIRED_MODULES := \
		e2fsdroid \

init/property_service.cpp

+98 −15

Original line number	Diff line number	Diff line
		@@ -50,17 +50,27 @@
		#include <android-base/strings.h>
		#include <bootimg.h>
		#include <fs_mgr.h>
		#include <property_info_parser/property_info_parser.h>
		#include <property_info_serializer/property_info_serializer.h>
		#include <selinux/android.h>
		#include <selinux/label.h>
		#include <selinux/selinux.h>

		#include "init.h"
		#include "persistent_properties.h"
		#include "space_tokenizer.h"
		#include "util.h"

		using android::base::ReadFileToString;
		using android::base::Split;
		using android::base::StartsWith;
		using android::base::StringPrintf;
		using android::base::Timer;
		using android::base::Trim;
		using android::base::WriteStringToFile;
		using android::properties::BuildTrie;
		using android::properties::PropertyInfoAreaFile;
		using android::properties::PropertyInfoEntry;

		#define RECOVERY_MOUNT_POINT "/recovery"

		@@ -71,26 +81,28 @@ static bool persistent_properties_loaded = false;

		static int property_set_fd = -1;

		static struct selabel_handle* sehandle_prop;
		static PropertyInfoAreaFile property_info_area;

		void CreateSerializedPropertyInfo();

		void property_init() {
		mkdir("/dev/__properties__", S_IRWXU \| S_IXGRP \| S_IXOTH);
		CreateSerializedPropertyInfo();
		if (__system_property_area_init()) {
		LOG(FATAL) << "Failed to initialize property area";
		}
		if (!property_info_area.LoadDefaultPath()) {
		LOG(FATAL) << "Failed to load serialized property info file";
		}
		}

		static bool check_mac_perms(const std::string& name, char* sctx, struct ucred* cr) {

		if (!sctx) {
		return false;
		}

		if (!sehandle_prop) {
		return false;
		}

		char* tctx = nullptr;
		if (selabel_lookup(sehandle_prop, &tctx, name.c_str(), 1) != 0) {
		const char* target_context = nullptr;
		property_info_area->GetPropertyInfo(name.c_str(), &target_context, nullptr);
		if (target_context == nullptr) {
		return false;
		}

		@@ -99,9 +111,9 @@ static bool check_mac_perms(const std::string& name, char* sctx, struct ucred* c
		audit_data.name = name.c_str();
		audit_data.cr = cr;

		bool has_access = (selinux_check_access(sctx, tctx, "property_service", "set", &audit_data) == 0);
		bool has_access =
		(selinux_check_access(sctx, target_context, "property_service", "set", &audit_data) == 0);

		freecon(tctx);
		return has_access;
		}

		@@ -433,7 +445,7 @@ static void handle_property_set(SocketConnection& socket,
		std::string cmdline_path = StringPrintf("proc/%d/cmdline", cr.pid);
		std::string process_cmdline;
		std::string process_log_string;
		if (android::base::ReadFileToString(cmdline_path, &process_cmdline)) {
		if (ReadFileToString(cmdline_path, &process_cmdline)) {
		// Since cmdline is null deliminated, .c_str() conveniently gives us just the process path.
		process_log_string = StringPrintf(" (%s)", process_cmdline.c_str());
		}
		@@ -714,9 +726,80 @@ static int SelinuxAuditCallback(void* data, security_class_t /cls/, char* buf,
		return 0;
		}

		void start_property_service() {
		sehandle_prop = selinux_android_prop_context_handle();
		Result<PropertyInfoEntry> ParsePropertyInfoLine(const std::string& line) {
		auto tokenizer = SpaceTokenizer(line);

		auto property = tokenizer.GetNext();
		if (property.empty()) return Error() << "Did not find a property entry in '" << line << "'";

		auto context = tokenizer.GetNext();
		if (context.empty()) return Error() << "Did not find a context entry in '" << line << "'";

		// It is not an error to not find these, as older files will not contain them.
		auto exact_match = tokenizer.GetNext();
		auto schema = tokenizer.GetRemaining();

		return {property, context, schema, exact_match == "exact"};
		}

		bool LoadPropertyInfoFromFile(const std::string& filename,
		std::vector<PropertyInfoEntry>* property_infos) {
		auto file_contents = std::string();
		if (!ReadFileToString(filename, &file_contents)) {
		PLOG(ERROR) << "Could not read properties from '" << filename << "'";
		return false;
		}

		for (const auto& line : Split(file_contents, "\n")) {
		auto trimmed_line = Trim(line);
		if (trimmed_line.empty() \|\| StartsWith(trimmed_line, "#")) {
		continue;
		}

		auto property_info = ParsePropertyInfoLine(line);
		if (!property_info) {
		LOG(ERROR) << "Could not read line from '" << filename << "': " << property_info.error();
		continue;
		}

		property_infos->emplace_back(*property_info);
		}
		return true;
		}

		void CreateSerializedPropertyInfo() {
		auto property_infos = std::vector<PropertyInfoEntry>();
		if (access("/system/etc/selinux/plat_property_contexts", R_OK) != -1) {
		if (!LoadPropertyInfoFromFile("/system/etc/selinux/plat_property_contexts",
		&property_infos)) {
		return;
		}
		// Don't check for failure here, so we always have a sane list of properties.
		// E.g. In case of recovery, the vendor partition will not have mounted and we
		// still need the system / platform properties to function.
		LoadPropertyInfoFromFile("/vendor/etc/selinux/nonplat_property_contexts", &property_infos);
		} else {
		if (!LoadPropertyInfoFromFile("/plat_property_contexts", &property_infos)) {
		return;
		}
		LoadPropertyInfoFromFile("/nonplat_property_contexts", &property_infos);
		}
		auto serialized_contexts = std::string();
		auto error = std::string();
		if (!BuildTrie(property_infos, "u:object_r:default_prop:s0", "\\s*", &serialized_contexts,
		&error)) {
		LOG(ERROR) << "Unable to serialize property contexts: " << error;
		return;
		}

		constexpr static const char kPropertyInfosPath[] = "/dev/__properties__/property_info";
		if (!WriteStringToFile(serialized_contexts, kPropertyInfosPath, 0444, 0, 0, false)) {
		PLOG(ERROR) << "Unable to write serialized property infos to file";
		}
		selinux_android_restorecon(kPropertyInfosPath, 0);
		}

		void start_property_service() {
		selinux_callback cb;
		cb.func_audit = SelinuxAuditCallback;
		selinux_set_callback(SELINUX_CB_AUDIT, cb);

init/space_tokenizer.h

0 → 100644

+50 −0

Original line number	Diff line number	Diff line
		/*
		* 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 _INIT_SPACE_TOKENIZER_H
		#define _INIT_SPACE_TOKENIZER_H

		namespace android {
		namespace init {

		class SpaceTokenizer {
		public:
		SpaceTokenizer(const std::string& string)
		: string_(string), it_(string_.begin()), end_(string_.end()) {}

		std::string GetNext() {
		auto next = std::string();
		while (it_ != end_ && !isspace(*it_)) {
		next.push_back(*it_++);
		}
		while (it_ != end_ && isspace(*it_)) {
		it_++;
		}
		return next;
		}

		std::string GetRemaining() { return std::string(it_, end_); }

		private:
		std::string string_;
		std::string::const_iterator it_;
		std::string::const_iterator end_;
		};

		} // namespace init
		} // namespace android

		#endif