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Add safety checks on KEY_INTENT mismatch.

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For many years, Parcel mismatch typed exploits has been using the
AccoungManagerService's passing of KEY_INTENT workflow, as a foothold of
launching arbitrary intents. We are adding an extra check on the service
side to simulate the final deserialization of the KEY_INTENT value, to
make sure the client side won't get a mismatched KEY_INTENT value.

Bug: 250588548
Bug: 240138294
Test: atest CtsAccountManagerTestCases
Test: local test, also see b/250588548
Change-Id: I433e34f6e21ce15c89825044a15b1dec46bb25cc
This commit is contained in:
Hao Ke
2022-10-04 19:43:58 +00:00
parent 8a2baf4e16
commit eb9a0566a5
1 changed files with 30 additions and 4 deletions
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34
services/core/java/com/android/server/accounts/AccountManagerService.java
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@@ -87,6 +87,7 @@ import android.os.SystemClock;
import android.os.UserHandle;
import android.os.UserManager;
import android.text.TextUtils;
import android.util.EventLog;
import android.util.Log;
import android.util.Pair;
import android.util.Slog;
@@ -3000,7 +3001,7 @@ public class AccountManagerService
*/
if (!checkKeyIntent(
Binder.getCallingUid(),
intent)) {
result)) {
onError(AccountManager.ERROR_CODE_INVALID_RESPONSE,
"invalid intent in bundle returned");
return;
@@ -3410,7 +3411,7 @@ public class AccountManagerService
&& (intent = result.getParcelable(AccountManager.KEY_INTENT)) != null) {
if (!checkKeyIntent(
Binder.getCallingUid(),
intent)) {
result)) {
onError(AccountManager.ERROR_CODE_INVALID_RESPONSE,
"invalid intent in bundle returned");
return;
@@ -4770,7 +4771,13 @@ public class AccountManagerService
* into launching arbitrary intents on the device via by tricking to click authenticator
* supplied entries in the system Settings app.
*/
protected boolean checkKeyIntent(int authUid, Intent intent) {
protected boolean checkKeyIntent(int authUid, Bundle bundle) {
if (!checkKeyIntentParceledCorrectly(bundle)) {
EventLog.writeEvent(0x534e4554, "250588548", authUid, "");
return false;
}
Intent intent = bundle.getParcelable(AccountManager.KEY_INTENT);
// Explicitly set an empty ClipData to ensure that we don't offer to
// promote any Uris contained inside for granting purposes
if (intent.getClipData() == null) {
@@ -4807,6 +4814,25 @@ public class AccountManagerService
}
}
/**
* Simulate the client side's deserialization of KEY_INTENT value, to make sure they don't
* violate our security policy.
*
* In particular we want to make sure the Authenticator doesn't trick users
* into launching arbitrary intents on the device via exploiting any other Parcel read/write
* mismatch problems.
*/
private boolean checkKeyIntentParceledCorrectly(Bundle bundle) {
Parcel p = Parcel.obtain();
p.writeBundle(bundle);
p.setDataPosition(0);
Bundle simulateBundle = p.readBundle();
p.recycle();
Intent intent = bundle.getParcelable(AccountManager.KEY_INTENT);
Intent simulateIntent = simulateBundle.getParcelable(AccountManager.KEY_INTENT);
return (intent.filterEquals(simulateIntent));
}
private boolean isExportedSystemActivity(ActivityInfo activityInfo) {
String className = activityInfo.name;
return "android".equals(activityInfo.packageName) &&
@@ -4953,7 +4979,7 @@ public class AccountManagerService
&& (intent = result.getParcelable(AccountManager.KEY_INTENT)) != null) {
if (!checkKeyIntent(
Binder.getCallingUid(),
intent)) {
result)) {
onError(AccountManager.ERROR_CODE_INVALID_RESPONSE,
"invalid intent in bundle returned");
return;