From 8cc5716ef109b3e7b8926fdced0aef1bb96368d0 Mon Sep 17 00:00:00 2001
From: Daniel Rosenberg <drosen@google.com>
Date: Thu, 6 Jun 2019 20:38:38 -0700
Subject: [PATCH] Defer deleteKey in KeyStorage in Checkpointing mode

Don't delete keys in checkpointing mode. Instead wait until the
checkpoint has been committed.

Bug: 134631661
Test: Flash A with a working build. Flash B with a broken build. Test
      that the device rolls back to A without getting sent to recovery.

Change-Id: Ie5fc2d098355e2d095c53e9a95a6a8c7ab7ed051
---
 KeyStorage.cpp | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/KeyStorage.cpp b/KeyStorage.cpp
index d00225b..0290086 100644
--- a/KeyStorage.cpp
+++ b/KeyStorage.cpp
@@ -19,7 +19,9 @@
 #include "Keymaster.h"
 #include "ScryptParameters.h"
 #include "Utils.h"
+#include "Checkpoint.h"
 
+#include <thread>
 #include <vector>
 
 #include <errno.h>
@@ -36,6 +38,7 @@
 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/unique_fd.h>
+#include <android-base/properties.h>
 
 #include <cutils/properties.h>
 
@@ -171,6 +174,28 @@ bool readSecdiscardable(const std::string& filename, std::string* hash) {
     return true;
 }
 
+static void deferedKmDeleteKey(const std::string& kmkey) {
+    while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
+        LOG(ERROR) << "Wait for boot timed out";
+    }
+    Keymaster keymaster;
+    if (!keymaster || !keymaster.deleteKey(kmkey)) {
+        LOG(ERROR) << "Defered Key deletion failed during upgrade";
+    }
+}
+
+bool kmDeleteKey(Keymaster& keymaster, const std::string& kmKey) {
+    bool needs_cp = cp_needsCheckpoint();
+
+    if (needs_cp) {
+        std::thread(deferedKmDeleteKey, kmKey).detach();
+        LOG(INFO) << "Deferring Key deletion during upgrade";
+        return true;
+    } else {
+        return keymaster.deleteKey(kmKey);
+    }
+}
+
 static KeymasterOperation begin(Keymaster& keymaster, const std::string& dir,
                                 km::KeyPurpose purpose, const km::AuthorizationSet& keyParams,
                                 const km::AuthorizationSet& opParams,
@@ -201,7 +226,7 @@ static KeymasterOperation begin(Keymaster& keymaster, const std::string& dir,
                 LOG(ERROR) << "Key dir sync failed: " << dir;
                 return KeymasterOperation();
             }
-            if (!keymaster.deleteKey(kmKey)) {
+            if (!kmDeleteKey(keymaster, kmKey)) {
                 LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
             }
         }