Add a new callback for the excessive binder proxy count
The callback is served as a warning where there are too many
binder proxies from a certain UID. The recipient of the callback
would then have a chance to log this event and/or trigger a dump,
before things getting out-of-control and trigger the high watermark
callback, where the process could be killed.
This callback signal could also be used as a hint to the GC in
the upper layer, which could effectively release the references to
remote binder stubs.
(cherry-picked from ag/25082740)
Bug: 298263955
Test: binder_bpBinderFuzz
Test: atest binderLibTest
Change-Id: I5d3659a9430c7404f7cfdfe4732980f5b1b0fa65
Merged-In: I5d3659a9430c7404f7cfdfe4732980f5b1b0fa65
diff --git a/libs/binder/tests/binderLibTest.cpp b/libs/binder/tests/binderLibTest.cpp
index 0ee96e7..2cea14f 100644
--- a/libs/binder/tests/binderLibTest.cpp
+++ b/libs/binder/tests/binderLibTest.cpp
@@ -115,6 +115,7 @@
BINDER_LIB_TEST_GET_SCHEDULING_POLICY,
BINDER_LIB_TEST_NOP_TRANSACTION_WAIT,
BINDER_LIB_TEST_GETPID,
+ BINDER_LIB_TEST_GETUID,
BINDER_LIB_TEST_ECHO_VECTOR,
BINDER_LIB_TEST_GET_NON_BLOCKING_FD,
BINDER_LIB_TEST_REJECT_OBJECTS,
@@ -1477,6 +1478,86 @@
EXPECT_EQ(BpBinder::getBinderProxyCount(), initialCount);
}
+static constexpr int kBpCountHighWatermark = 20;
+static constexpr int kBpCountLowWatermark = 10;
+static constexpr int kBpCountWarningWatermark = 15;
+static constexpr int kInvalidUid = -1;
+
+TEST_F(BinderLibTest, BinderProxyCountCallback) {
+ Parcel data, reply;
+ sp<IBinder> server = addServer();
+ ASSERT_NE(server, nullptr);
+
+ BpBinder::enableCountByUid();
+ EXPECT_THAT(m_server->transact(BINDER_LIB_TEST_GETUID, data, &reply), StatusEq(NO_ERROR));
+ int32_t uid = reply.readInt32();
+ ASSERT_NE(uid, kInvalidUid);
+
+ uint32_t initialCount = BpBinder::getBinderProxyCount();
+ {
+ uint32_t count = initialCount;
+ BpBinder::setBinderProxyCountWatermarks(kBpCountHighWatermark,
+ kBpCountLowWatermark,
+ kBpCountWarningWatermark);
+ int limitCallbackUid = kInvalidUid;
+ int warningCallbackUid = kInvalidUid;
+ BpBinder::setBinderProxyCountEventCallback([&](int uid) { limitCallbackUid = uid; },
+ [&](int uid) { warningCallbackUid = uid; });
+
+ std::vector<sp<IBinder> > proxies;
+ auto createProxyOnce = [&](int expectedWarningCallbackUid, int expectedLimitCallbackUid) {
+ warningCallbackUid = limitCallbackUid = kInvalidUid;
+ ASSERT_THAT(server->transact(BINDER_LIB_TEST_CREATE_BINDER_TRANSACTION, data, &reply),
+ StatusEq(NO_ERROR));
+ proxies.push_back(reply.readStrongBinder());
+ EXPECT_EQ(BpBinder::getBinderProxyCount(), ++count);
+ EXPECT_EQ(warningCallbackUid, expectedWarningCallbackUid);
+ EXPECT_EQ(limitCallbackUid, expectedLimitCallbackUid);
+ };
+ auto removeProxyOnce = [&](int expectedWarningCallbackUid, int expectedLimitCallbackUid) {
+ warningCallbackUid = limitCallbackUid = kInvalidUid;
+ proxies.pop_back();
+ EXPECT_EQ(BpBinder::getBinderProxyCount(), --count);
+ EXPECT_EQ(warningCallbackUid, expectedWarningCallbackUid);
+ EXPECT_EQ(limitCallbackUid, expectedLimitCallbackUid);
+ };
+
+ // Test the increment/decrement of the binder proxies.
+ for (int i = 1; i <= kBpCountWarningWatermark; i++) {
+ createProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ createProxyOnce(uid, kInvalidUid); // Warning callback should have been triggered.
+ for (int i = kBpCountWarningWatermark + 2; i <= kBpCountHighWatermark; i++) {
+ createProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ createProxyOnce(kInvalidUid, uid); // Limit callback should have been triggered.
+ createProxyOnce(kInvalidUid, kInvalidUid);
+ for (int i = kBpCountHighWatermark + 2; i >= kBpCountHighWatermark; i--) {
+ removeProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ createProxyOnce(kInvalidUid, kInvalidUid);
+
+ // Go down below the low watermark.
+ for (int i = kBpCountHighWatermark; i >= kBpCountLowWatermark; i--) {
+ removeProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ for (int i = kBpCountLowWatermark; i <= kBpCountWarningWatermark; i++) {
+ createProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ createProxyOnce(uid, kInvalidUid); // Warning callback should have been triggered.
+ for (int i = kBpCountWarningWatermark + 2; i <= kBpCountHighWatermark; i++) {
+ createProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ createProxyOnce(kInvalidUid, uid); // Limit callback should have been triggered.
+ createProxyOnce(kInvalidUid, kInvalidUid);
+ for (int i = kBpCountHighWatermark + 2; i >= kBpCountHighWatermark; i--) {
+ removeProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ createProxyOnce(kInvalidUid, kInvalidUid);
+ }
+ EXPECT_EQ(BpBinder::getBinderProxyCount(), initialCount);
+}
+
class BinderLibRpcTestBase : public BinderLibTest {
public:
void SetUp() override {
@@ -1680,6 +1761,9 @@
case BINDER_LIB_TEST_GETPID:
reply->writeInt32(getpid());
return NO_ERROR;
+ case BINDER_LIB_TEST_GETUID:
+ reply->writeInt32(getuid());
+ return NO_ERROR;
case BINDER_LIB_TEST_NOP_TRANSACTION_WAIT:
usleep(5000);
[[fallthrough]];