/*
|
* 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.
|
*/
|
|
#define LOG_TAG "hwservicemanager"
|
|
#include <android-base/logging.h>
|
#include <hidl-util/FQName.h>
|
#include <log/log.h>
|
|
#include "AccessControl.h"
|
|
namespace android {
|
|
static const char *kPermissionAdd = "add";
|
static const char *kPermissionGet = "find";
|
static const char *kPermissionList = "list";
|
|
struct audit_data {
|
const char* interfaceName;
|
const char* sid;
|
pid_t pid;
|
};
|
|
using android::FQName;
|
|
AccessControl::AccessControl() {
|
mSeHandle = selinux_android_hw_service_context_handle();
|
LOG_ALWAYS_FATAL_IF(mSeHandle == nullptr, "Failed to acquire SELinux handle.");
|
|
if (getcon(&mSeContext) != 0) {
|
LOG_ALWAYS_FATAL("Failed to acquire hwservicemanager context.");
|
}
|
|
selinux_status_open(true);
|
|
mSeCallbacks.func_audit = AccessControl::auditCallback;
|
selinux_set_callback(SELINUX_CB_AUDIT, mSeCallbacks);
|
|
mSeCallbacks.func_log = selinux_log_callback; /* defined in libselinux */
|
selinux_set_callback(SELINUX_CB_LOG, mSeCallbacks);
|
}
|
|
bool AccessControl::canAdd(const std::string& fqName, const CallingContext& callingContext) {
|
FQName fqIface;
|
|
if (!FQName::parse(fqName, &fqIface)) {
|
return false;
|
}
|
const std::string checkName = fqIface.package() + "::" + fqIface.name();
|
|
return checkPermission(callingContext, kPermissionAdd, checkName.c_str());
|
}
|
|
bool AccessControl::canGet(const std::string& fqName, const CallingContext& callingContext) {
|
FQName fqIface;
|
|
if (!FQName::parse(fqName, &fqIface)) {
|
return false;
|
}
|
const std::string checkName = fqIface.package() + "::" + fqIface.name();
|
|
return checkPermission(callingContext, kPermissionGet, checkName.c_str());
|
}
|
|
bool AccessControl::canList(const CallingContext& callingContext) {
|
return checkPermission(callingContext, mSeContext, kPermissionList, nullptr);
|
}
|
|
AccessControl::CallingContext AccessControl::getCallingContext(pid_t sourcePid) {
|
char *sourceContext = nullptr;
|
|
if (getpidcon(sourcePid, &sourceContext) < 0) {
|
ALOGE("SELinux: failed to retrieve process context for pid %d", sourcePid);
|
return { false, "", sourcePid };
|
}
|
|
std::string context = sourceContext;
|
freecon(sourceContext);
|
return { true, context, sourcePid };
|
}
|
|
bool AccessControl::checkPermission(const CallingContext& source, const char *targetContext, const char *perm, const char *interface) {
|
if (!source.sidPresent) {
|
return false;
|
}
|
|
bool allowed = false;
|
|
struct audit_data ad;
|
ad.pid = source.pid;
|
ad.sid = source.sid.c_str();
|
ad.interfaceName = interface;
|
|
allowed = (selinux_check_access(source.sid.c_str(), targetContext, "hwservice_manager",
|
perm, (void *) &ad) == 0);
|
|
return allowed;
|
}
|
|
bool AccessControl::checkPermission(const CallingContext& source, const char *perm, const char *interface) {
|
char *targetContext = nullptr;
|
bool allowed = false;
|
|
// Lookup service in hwservice_contexts
|
if (selabel_lookup(mSeHandle, &targetContext, interface, 0) != 0) {
|
ALOGE("No match for interface %s in hwservice_contexts", interface);
|
return false;
|
}
|
|
allowed = checkPermission(source, targetContext, perm, interface);
|
|
freecon(targetContext);
|
|
return allowed;
|
}
|
|
int AccessControl::auditCallback(void *data, security_class_t /*cls*/, char *buf, size_t len) {
|
struct audit_data *ad = (struct audit_data *)data;
|
|
if (!ad || !ad->interfaceName) {
|
ALOGE("No valid hwservicemanager audit data");
|
return 0;
|
}
|
|
const char* sid = ad->sid ? ad->sid : "N/A";
|
|
snprintf(buf, len, "interface=%s sid=%s pid=%d", ad->interfaceName, sid, ad->pid);
|
return 0;
|
}
|
|
} // namespace android
|
