Add security check to getPhysicalDisplayToken binder function.
- There is a possible way to take over the screen display and swap the
display content due to a missing permission check.
- Add a short-term fix for WCG checking failure because of new
permission check added to SF::getPhysicalDisplayToken: change two
function signatures (getStaticDisplayInfo and getDynamicDisplayInfo).
- To make short-term fix workable, split getDynamicDisplayInfo binder
call into two, one is to take display id, one is to take display token
as old codes show to avoid huge modification on other callees.
Bug: 248031255
Test: test using displaytoken app manually on the phone, test shell
screenrecord during using displaytoken; atest
android.hardware.camera2.cts.FastBasicsTest
Change-Id: Id9d9012d4ede9c8330f0ce1096bcb78e51b7c5df
diff --git a/services/surfaceflinger/tests/Credentials_test.cpp b/services/surfaceflinger/tests/Credentials_test.cpp
index 1676844..4a45eb5 100644
--- a/services/surfaceflinger/tests/Credentials_test.cpp
+++ b/services/surfaceflinger/tests/Credentials_test.cpp
@@ -83,6 +83,15 @@
return SurfaceComposerClient::getPhysicalDisplayToken(ids.front());
}
+ static std::optional<uint64_t> getFirstDisplayId() {
+ const auto ids = SurfaceComposerClient::getPhysicalDisplayIds();
+ if (ids.empty()) {
+ return std::nullopt;
+ }
+
+ return ids.front().value;
+ }
+
void setupBackgroundSurface() {
mDisplay = getFirstDisplayToken();
ASSERT_FALSE(mDisplay == nullptr);
@@ -169,29 +178,25 @@
TEST_F(CredentialsTest, GetBuiltInDisplayAccessTest) {
std::function<bool()> condition = [] { return getFirstDisplayToken() != nullptr; };
// Anyone can access display information.
- ASSERT_NO_FATAL_FAILURE(checkWithPrivileges(condition, true, true));
+ ASSERT_NO_FATAL_FAILURE(checkWithPrivileges(condition, true, false));
}
TEST_F(CredentialsTest, AllowedGetterMethodsTest) {
// The following methods are tested with a UID that is not root, graphics,
// or system, to show that anyone can access them.
UIDFaker f(AID_BIN);
- const auto display = getFirstDisplayToken();
- ASSERT_TRUE(display != nullptr);
-
- ui::DisplayMode mode;
- ASSERT_EQ(NO_ERROR, SurfaceComposerClient::getActiveDisplayMode(display, &mode));
-
- Vector<ui::DisplayMode> modes;
+ const auto id = getFirstDisplayId();
+ ASSERT_TRUE(id);
ui::DynamicDisplayInfo info;
- ASSERT_EQ(NO_ERROR, SurfaceComposerClient::getDynamicDisplayInfo(display, &info));
+ ASSERT_EQ(NO_ERROR, SurfaceComposerClient::getDynamicDisplayInfoFromId(*id, &info));
}
TEST_F(CredentialsTest, GetDynamicDisplayInfoTest) {
- const auto display = getFirstDisplayToken();
+ const auto id = getFirstDisplayId();
+ ASSERT_TRUE(id);
std::function<status_t()> condition = [=]() {
ui::DynamicDisplayInfo info;
- return SurfaceComposerClient::getDynamicDisplayInfo(display, &info);
+ return SurfaceComposerClient::getDynamicDisplayInfoFromId(*id, &info);
};
ASSERT_NO_FATAL_FAILURE(checkWithPrivileges<status_t>(condition, NO_ERROR, NO_ERROR));
}
@@ -335,8 +340,10 @@
status_t error = SurfaceComposerClient::isWideColorDisplay(display, &result);
ASSERT_EQ(NO_ERROR, error);
bool hasWideColorMode = false;
+ const auto id = getFirstDisplayId();
+ ASSERT_TRUE(id);
ui::DynamicDisplayInfo info;
- SurfaceComposerClient::getDynamicDisplayInfo(display, &info);
+ SurfaceComposerClient::getDynamicDisplayInfoFromId(*id, &info);
const auto& colorModes = info.supportedColorModes;
for (ColorMode colorMode : colorModes) {
switch (colorMode) {
@@ -363,10 +370,10 @@
}
TEST_F(CredentialsTest, GetActiveColorModeBasicCorrectness) {
- const auto display = getFirstDisplayToken();
- ASSERT_FALSE(display == nullptr);
+ const auto id = getFirstDisplayId();
+ ASSERT_TRUE(id);
ui::DynamicDisplayInfo info;
- SurfaceComposerClient::getDynamicDisplayInfo(display, &info);
+ SurfaceComposerClient::getDynamicDisplayInfoFromId(*id, &info);
ColorMode colorMode = info.activeColorMode;
ASSERT_NE(static_cast<ColorMode>(BAD_VALUE), colorMode);
}