145 lines
4.3 KiB
C++
145 lines
4.3 KiB
C++
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#define LOG_TAG "hwservicemanager"
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#include <android-base/logging.h>
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#include <hidl-util/FQName.h>
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#include <log/log.h>
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#include "AccessControl.h"
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namespace android {
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static const char *kPermissionAdd = "add";
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static const char *kPermissionGet = "find";
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static const char *kPermissionList = "list";
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struct audit_data {
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const char* interfaceName;
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const char* sid;
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pid_t pid;
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};
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using android::FQName;
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AccessControl::AccessControl() {
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mSeHandle = selinux_android_hw_service_context_handle();
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LOG_ALWAYS_FATAL_IF(mSeHandle == nullptr, "Failed to acquire SELinux handle.");
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if (getcon(&mSeContext) != 0) {
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LOG_ALWAYS_FATAL("Failed to acquire hwservicemanager context.");
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}
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selinux_status_open(true);
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mSeCallbacks.func_audit = AccessControl::auditCallback;
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selinux_set_callback(SELINUX_CB_AUDIT, mSeCallbacks);
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mSeCallbacks.func_log = selinux_log_callback; /* defined in libselinux */
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selinux_set_callback(SELINUX_CB_LOG, mSeCallbacks);
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}
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bool AccessControl::canAdd(const std::string& fqName, const CallingContext& callingContext) {
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FQName fqIface;
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if (!FQName::parse(fqName, &fqIface)) {
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return false;
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}
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const std::string checkName = fqIface.package() + "::" + fqIface.name();
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return checkPermission(callingContext, kPermissionAdd, checkName.c_str());
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}
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bool AccessControl::canGet(const std::string& fqName, const CallingContext& callingContext) {
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FQName fqIface;
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if (!FQName::parse(fqName, &fqIface)) {
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return false;
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}
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const std::string checkName = fqIface.package() + "::" + fqIface.name();
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return checkPermission(callingContext, kPermissionGet, checkName.c_str());
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}
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bool AccessControl::canList(const CallingContext& callingContext) {
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return checkPermission(callingContext, mSeContext, kPermissionList, nullptr);
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}
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AccessControl::CallingContext AccessControl::getCallingContext(pid_t sourcePid) {
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char *sourceContext = nullptr;
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if (getpidcon(sourcePid, &sourceContext) < 0) {
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ALOGE("SELinux: failed to retrieve process context for pid %d", sourcePid);
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return { false, "", sourcePid };
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}
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std::string context = sourceContext;
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freecon(sourceContext);
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return { true, context, sourcePid };
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}
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bool AccessControl::checkPermission(const CallingContext& source, const char *targetContext, const char *perm, const char *interface) {
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if (!source.sidPresent) {
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return false;
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}
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bool allowed = false;
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struct audit_data ad;
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ad.pid = source.pid;
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ad.sid = source.sid.c_str();
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ad.interfaceName = interface;
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allowed = (selinux_check_access(source.sid.c_str(), targetContext, "hwservice_manager",
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perm, (void *) &ad) == 0);
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return allowed;
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}
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bool AccessControl::checkPermission(const CallingContext& source, const char *perm, const char *interface) {
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char *targetContext = nullptr;
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bool allowed = false;
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// Lookup service in hwservice_contexts
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if (selabel_lookup(mSeHandle, &targetContext, interface, 0) != 0) {
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ALOGE("No match for interface %s in hwservice_contexts", interface);
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return false;
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}
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allowed = checkPermission(source, targetContext, perm, interface);
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freecon(targetContext);
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return allowed;
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}
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int AccessControl::auditCallback(void *data, security_class_t /*cls*/, char *buf, size_t len) {
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struct audit_data *ad = (struct audit_data *)data;
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if (!ad || !ad->interfaceName) {
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ALOGE("No valid hwservicemanager audit data");
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return 0;
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}
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const char* sid = ad->sid ? ad->sid : "N/A";
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snprintf(buf, len, "interface=%s sid=%s pid=%d", ad->interfaceName, sid, ad->pid);
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return 0;
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}
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} // namespace android
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