From a946b9e2419e0d7f29a52a047c70857eb9251cbd Mon Sep 17 00:00:00 2001
From: Tianjie Xu <xunchang@google.com>
Date: Tue, 21 Mar 2017 16:24:57 -0700
Subject: Fix the permission of stashed blocks created by updater

Our updater created the stashes with root permission. This causes an
access denial when the RecoverySystem service tries to clean up these
blocks after a failing update. As a result, the subsequent OTA updates
may fail due to insufficient cache space.

Bug: 36457133
Test: stashed blocks cleaned successfully after reboot
Change-Id: If0ca99638cdfa1033646f29d9cc92b5ff1bacac1
---
 updater/blockimg.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/updater/blockimg.cpp b/updater/blockimg.cpp
index 0fa83d9d5..8dbd8c7d1 100644
--- a/updater/blockimg.cpp
+++ b/updater/blockimg.cpp
@@ -44,6 +44,7 @@
 #include <android-base/unique_fd.h>
 #include <applypatch/applypatch.h>
 #include <openssl/sha.h>
+#include <private/android_filesystem_config.h>
 #include <ziparchive/zip_archive.h>
 
 #include "edify/expr.h"
@@ -772,6 +773,11 @@ static int WriteStash(const std::string& base, const std::string& id, int blocks
         return -1;
     }
 
+    if (fchown(fd, AID_SYSTEM, AID_SYSTEM) != 0) {  // system user
+        PLOG(ERROR) << "failed to chown \"" << fn << "\"";
+        return -1;
+    }
+
     if (write_all(fd, buffer, blocks * BLOCKSIZE) == -1) {
         return -1;
     }
@@ -841,6 +847,12 @@ static int CreateStash(State* state, size_t maxblocks, const std::string& blockd
       return -1;
     }
 
+    if (chown(dirname.c_str(), AID_SYSTEM, AID_SYSTEM) != 0) {  // system user
+      ErrorAbort(state, kStashCreationFailure, "chown \"%s\" failed: %s\n", dirname.c_str(),
+                 strerror(errno));
+      return -1;
+    }
+
     if (CacheSizeCheck(max_stash_size) != 0) {
       ErrorAbort(state, kStashCreationFailure, "not enough space for stash (%zu needed)\n",
                  max_stash_size);
-- 
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