No sensor access to idle UIDs - native framework
Idle UIDs are ones that were in the background for long enough time.
Currently such apps can access sensor data even though they have no
user perceptible components running. This affects the user's privacy
since an app in the background can use sensor data to infer location,
activity, habits, etc.
The goal is to restrict sensor access for all apps in the ecosystem
regardless of target SDK which means the solution should be backwards
compatible. At the high level the sesnor service observes UID state
changes and applies policy like this:
Continuous sensors: for sensros in this reporting mode when the UID
goes in the background we will stop dispatching events. Once the UID
goes active we will start reporting the events. While this is an
app visible behavior change we would rather do that vs delivering
fake events.
Flush events: there is no change in behavior based on the UID state.
Hence, idle apps can request a flush and would get the completion
callback. From an app perspective flushing works at any point.
Trigger events: for sensors in this reporting mode when the UID
goes in the background we will not report any trigger events. From
an app perspective the sensor just did not pick up any events.
On-change events: for sensors in this reporting mode when the UID
goes in the background we will not report any change events. From
an app perspective the sensor just did not pick up any events.
Wake locks: since UIDs in idle state cannot acquire wakelocks we
will not be grabbing a wakelock on behalf of apps in that state.
Test: Added - SensorTest#testSanitizedContinuousEventsUidIdle
Added - SensorTest#testBatchAndFlushUidIdle
Pass - cts-tradefed run cts-dev -m CtsSensorTestCases
bug:63938985
Change-Id: I156803610ad6d86afaae641ebbb0e84f16d2344b
diff --git a/services/sensorservice/SensorService.cpp b/services/sensorservice/SensorService.cpp
index dc491d9..c32ffb9 100644
--- a/services/sensorservice/SensorService.cpp
+++ b/services/sensorservice/SensorService.cpp
@@ -13,11 +13,14 @@
* See the License for the specific language governing permissions and
* limitations under the License.
*/
+#include <binder/ActivityManager.h>
#include <binder/AppOpsManager.h>
#include <binder/BinderService.h>
#include <binder/IServiceManager.h>
#include <binder/PermissionCache.h>
+#include <binder/PermissionController.h>
#include <cutils/ashmem.h>
+#include <cutils/misc.h>
#include <cutils/properties.h>
#include <hardware/sensors.h>
#include <hardware_legacy/power.h>
@@ -52,6 +55,8 @@
#include <sys/types.h>
#include <unistd.h>
+#include <private/android_filesystem_config.h>
+
namespace android {
// ---------------------------------------------------------------------------
@@ -75,6 +80,7 @@
// Permissions.
static const String16 sDumpPermission("android.permission.DUMP");
static const String16 sLocationHardwarePermission("android.permission.LOCATION_HARDWARE");
+static const String16 sManageSensorsPermission("android.permission.MANAGE_SENSORS");
SensorService::SensorService()
: mInitCheck(NO_INIT), mSocketBufferSize(SOCKET_BUFFER_SIZE_NON_BATCHED),
@@ -274,6 +280,23 @@
// priority can only be changed after run
enableSchedFifoMode();
+
+ // Start watching UID changes to apply policy.
+ mUidPolicy = new UidPolicy(this);
+ mUidPolicy->registerSelf();
+ }
+ }
+}
+
+void SensorService::setSensorAccess(uid_t uid, bool hasAccess) {
+ SortedVector< sp<SensorEventConnection> > activeConnections;
+ populateActiveConnections(&activeConnections);
+ {
+ Mutex::Autolock _l(mLock);
+ for (size_t i = 0 ; i < activeConnections.size(); i++) {
+ if (activeConnections[i] != 0 && activeConnections[i]->getUid() == uid) {
+ activeConnections[i]->setSensorAccess(hasAccess);
+ }
}
}
}
@@ -312,6 +335,7 @@
for (auto && entry : mRecentEvent) {
delete entry.second;
}
+ mUidPolicy->unregisterSelf();
}
status_t SensorService::dump(int fd, const Vector<String16>& args) {
@@ -488,6 +512,82 @@
return NO_ERROR;
}
+// NOTE: This is a remote API - make sure all args are validated
+status_t SensorService::shellCommand(int in, int out, int err, Vector<String16>& args) {
+ if (!checkCallingPermission(sManageSensorsPermission, nullptr, nullptr)) {
+ return PERMISSION_DENIED;
+ }
+ if (in == BAD_TYPE || out == BAD_TYPE || err == BAD_TYPE) {
+ return BAD_VALUE;
+ }
+ if (args.size() == 3 && args[0] == String16("set-uid-state")) {
+ return handleSetUidState(args, err);
+ } else if (args.size() == 2 && args[0] == String16("reset-uid-state")) {
+ return handleResetUidState(args, err);
+ } else if (args.size() == 2 && args[0] == String16("get-uid-state")) {
+ return handleGetUidState(args, out, err);
+ } else if (args.size() == 1 && args[0] == String16("help")) {
+ printHelp(out);
+ return NO_ERROR;
+ }
+ printHelp(err);
+ return BAD_VALUE;
+}
+
+status_t SensorService::handleSetUidState(Vector<String16>& args, int err) {
+ PermissionController pc;
+ int uid = pc.getPackageUid(args[1], 0);
+ if (uid <= 0) {
+ ALOGE("Unknown package: '%s'", String8(args[1]).string());
+ dprintf(err, "Unknown package: '%s'\n", String8(args[1]).string());
+ return BAD_VALUE;
+ }
+ bool active = false;
+ if (args[2] == String16("active")) {
+ active = true;
+ } else if ((args[2] != String16("idle"))) {
+ ALOGE("Expected active or idle but got: '%s'", String8(args[2]).string());
+ return BAD_VALUE;
+ }
+ mUidPolicy->addOverrideUid(uid, active);
+ return NO_ERROR;
+}
+
+status_t SensorService::handleResetUidState(Vector<String16>& args, int err) {
+ PermissionController pc;
+ int uid = pc.getPackageUid(args[1], 0);
+ if (uid < 0) {
+ ALOGE("Unknown package: '%s'", String8(args[1]).string());
+ dprintf(err, "Unknown package: '%s'\n", String8(args[1]).string());
+ return BAD_VALUE;
+ }
+ mUidPolicy->removeOverrideUid(uid);
+ return NO_ERROR;
+}
+
+status_t SensorService::handleGetUidState(Vector<String16>& args, int out, int err) {
+ PermissionController pc;
+ int uid = pc.getPackageUid(args[1], 0);
+ if (uid < 0) {
+ ALOGE("Unknown package: '%s'", String8(args[1]).string());
+ dprintf(err, "Unknown package: '%s'\n", String8(args[1]).string());
+ return BAD_VALUE;
+ }
+ if (mUidPolicy->isUidActive(uid)) {
+ return dprintf(out, "active\n");
+ } else {
+ return dprintf(out, "idle\n");
+ }
+}
+
+status_t SensorService::printHelp(int out) {
+ return dprintf(out, "Sensor service commands:\n"
+ " get-uid-state <PACKAGE> gets the uid state\n"
+ " set-uid-state <PACKAGE> <active|idle> overrides the uid state\n"
+ " reset-uid-state <PACKAGE> clears the uid state override\n"
+ " help print this message\n");
+}
+
//TODO: move to SensorEventConnection later
void SensorService::cleanupAutoDisabledSensorLocked(const sp<SensorEventConnection>& connection,
sensors_event_t const* buffer, const int count) {
@@ -677,7 +777,6 @@
}
}
-
// Send our events to clients. Check the state of wake lock for each client and release the
// lock if none of the clients need it.
bool needsWakeLock = false;
@@ -939,8 +1038,9 @@
(packageName == "") ? String8::format("unknown_package_pid_%d", pid) : packageName;
String16 connOpPackageName =
(opPackageName == String16("")) ? String16(connPackageName) : opPackageName;
+ bool hasSensorAccess = mUidPolicy->isUidActive(uid);
sp<SensorEventConnection> result(new SensorEventConnection(this, uid, connPackageName,
- requestedMode == DATA_INJECTION, connOpPackageName));
+ requestedMode == DATA_INJECTION, connOpPackageName, hasSensorAccess));
if (requestedMode == DATA_INJECTION) {
if (mActiveConnections.indexOf(result) < 0) {
mActiveConnections.add(result);
@@ -1530,4 +1630,98 @@
return false;
}
+void SensorService::UidPolicy::registerSelf() {
+ ActivityManager am;
+ am.registerUidObserver(this, ActivityManager::UID_OBSERVER_GONE
+ | ActivityManager::UID_OBSERVER_IDLE
+ | ActivityManager::UID_OBSERVER_ACTIVE,
+ ActivityManager::PROCESS_STATE_UNKNOWN,
+ String16("android"));
+}
+
+void SensorService::UidPolicy::unregisterSelf() {
+ ActivityManager am;
+ am.unregisterUidObserver(this);
+}
+
+void SensorService::UidPolicy::onUidGone(__unused uid_t uid, __unused bool disabled) {
+ onUidIdle(uid, disabled);
+}
+
+void SensorService::UidPolicy::onUidActive(uid_t uid) {
+ {
+ Mutex::Autolock _l(mUidLock);
+ mActiveUids.insert(uid);
+ }
+ sp<SensorService> service = mService.promote();
+ if (service != nullptr) {
+ service->setSensorAccess(uid, true);
+ }
+}
+
+void SensorService::UidPolicy::onUidIdle(uid_t uid, __unused bool disabled) {
+ bool deleted = false;
+ {
+ Mutex::Autolock _l(mUidLock);
+ if (mActiveUids.erase(uid) > 0) {
+ deleted = true;
+ }
+ }
+ if (deleted) {
+ sp<SensorService> service = mService.promote();
+ if (service != nullptr) {
+ service->setSensorAccess(uid, false);
+ }
+ }
+}
+
+void SensorService::UidPolicy::addOverrideUid(uid_t uid, bool active) {
+ updateOverrideUid(uid, active, true);
+}
+
+void SensorService::UidPolicy::removeOverrideUid(uid_t uid) {
+ updateOverrideUid(uid, false, false);
+}
+
+void SensorService::UidPolicy::updateOverrideUid(uid_t uid, bool active, bool insert) {
+ bool wasActive = false;
+ bool isActive = false;
+ {
+ Mutex::Autolock _l(mUidLock);
+ wasActive = isUidActiveLocked(uid);
+ mOverrideUids.erase(uid);
+ if (insert) {
+ mOverrideUids.insert(std::pair<uid_t, bool>(uid, active));
+ }
+ isActive = isUidActiveLocked(uid);
+ }
+ if (wasActive != isActive) {
+ sp<SensorService> service = mService.promote();
+ if (service != nullptr) {
+ service->setSensorAccess(uid, isActive);
+ }
+ }
+}
+
+bool SensorService::UidPolicy::isUidActive(uid_t uid) {
+ // Non-app UIDs are considered always active
+ if (uid < FIRST_APPLICATION_UID) {
+ return true;
+ }
+ Mutex::Autolock _l(mUidLock);
+ return isUidActiveLocked(uid);
+}
+
+bool SensorService::UidPolicy::isUidActiveLocked(uid_t uid) {
+ // Non-app UIDs are considered always active
+ if (uid < FIRST_APPLICATION_UID) {
+ return true;
+ }
+ auto it = mOverrideUids.find(uid);
+ if (it != mOverrideUids.end()) {
+ return it->second;
+ }
+ return mActiveUids.find(uid) != mActiveUids.end();
+}
+
}; // namespace android