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AudioService: validate uid / package name match

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When checking app ops, check for exceptions that indicate uid
and package name mismatch.
This affects the code paths for methods:
- adjustStreamVolume
- setStreamVolume
- setMicrophoneMute
- setMasterMute

Bug: 194110891, 194110526
Test: see bug exploit app, verify real/bogus package shows uninstalled
Change-Id: I5cdd52899bc3c89b41bc6074568e2b62637c005c
This commit is contained in:
Jean-Michel Trivi
2021-08-23 09:50:35 -07:00
parent 8e6102074e
commit 33ef94742e
1 changed files with 37 additions and 8 deletions
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45
services/core/java/com/android/server/audio/AudioService.java
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@@ -2825,8 +2825,9 @@ public class AudioService extends IAudioService.Stub
if (uid == android.os.Process.SYSTEM_UID) {
uid = UserHandle.getUid(getCurrentUserId(), UserHandle.getAppId(uid));
}
if (mAppOps.noteOp(STREAM_VOLUME_OPS[streamTypeAlias], uid,
callingPackage, attributionTag, null) != AppOpsManager.MODE_ALLOWED) {
// validate calling package and app op
if (!checkNoteAppOp(
STREAM_VOLUME_OPS[streamTypeAlias], uid, callingPackage, attributionTag)) {
return;
}
@@ -3536,8 +3537,8 @@ public class AudioService extends IAudioService.Stub
if (uid == android.os.Process.SYSTEM_UID) {
uid = UserHandle.getUid(getCurrentUserId(), UserHandle.getAppId(uid));
}
if (mAppOps.noteOp(STREAM_VOLUME_OPS[streamTypeAlias], uid,
callingPackage, attributionTag, null) != AppOpsManager.MODE_ALLOWED) {
if (!checkNoteAppOp(
STREAM_VOLUME_OPS[streamTypeAlias], uid, callingPackage, attributionTag)) {
return;
}
@@ -3956,8 +3957,8 @@ public class AudioService extends IAudioService.Stub
uid = UserHandle.getUid(userId, UserHandle.getAppId(uid));
}
// If OP_AUDIO_MASTER_VOLUME is set, disallow unmuting.
if (!mute && mAppOps.noteOp(AppOpsManager.OP_AUDIO_MASTER_VOLUME, uid,
callingPackage, attributionTag, null) != AppOpsManager.MODE_ALLOWED) {
if (!mute && !checkNoteAppOp(
AppOpsManager.OP_AUDIO_MASTER_VOLUME, uid, callingPackage, attributionTag)) {
return;
}
if (userId != UserHandle.getCallingUserId() &&
@@ -4090,8 +4091,8 @@ public class AudioService extends IAudioService.Stub
? MediaMetrics.Value.MUTE : MediaMetrics.Value.UNMUTE);
// If OP_MUTE_MICROPHONE is set, disallow unmuting.
if (!on && mAppOps.noteOp(AppOpsManager.OP_MUTE_MICROPHONE, uid,
callingPackage, attributionTag, null) != AppOpsManager.MODE_ALLOWED) {
if (!on && !checkNoteAppOp(
AppOpsManager.OP_MUTE_MICROPHONE, uid, callingPackage, attributionTag)) {
mmi.set(MediaMetrics.Property.EARLY_RETURN, "disallow unmuting").record();
return;
}
@@ -10574,4 +10575,32 @@ public class AudioService extends IAudioService.Stub
}
mFullVolumeDevices.remove(audioSystemDeviceOut);
}
//====================
// Helper functions for app ops
//====================
/**
* Validates, and notes an app op for a given uid and package name.
* Validation comes from exception catching: a security exception indicates the package
* doesn't exist, an IAE indicates the uid and package don't match. The code only checks
* if exception was thrown for robustness to code changes in op validation
* @param op the app op to check
* @param uid the uid of the caller
* @param packageName the package to check
* @return true if the origin of the call is valid (no uid / package mismatch) and the caller
* is allowed to perform the operation
*/
private boolean checkNoteAppOp(int op, int uid, String packageName, String attributionTag) {
try {
if (mAppOps.noteOp(op, uid, packageName, attributionTag, null)
!= AppOpsManager.MODE_ALLOWED) {
return false;
}
} catch (Exception e) {
Log.e(TAG, "Error noting op:" + op + " on uid:" + uid + " for package:"
+ packageName, e);
return false;
}
return true;
}
}