diff --git a/cmds/installd/InstalldNativeService.cpp b/cmds/installd/InstalldNativeService.cpp
index c604ca0..20b960d 100644
--- a/cmds/installd/InstalldNativeService.cpp
+++ b/cmds/installd/InstalldNativeService.cpp
@@ -88,6 +88,7 @@
 static constexpr int FLAG_FREE_CACHE_V2 = 1 << 13;
 static constexpr int FLAG_FREE_CACHE_V2_DEFY_QUOTA = 1 << 14;
 static constexpr int FLAG_FREE_CACHE_NOOP = 1 << 15;
+static constexpr int FLAG_FORCE = 1 << 16;
 
 namespace {
 
@@ -600,6 +601,113 @@
     return res;
 }
 
+static gid_t get_cache_gid(uid_t uid) {
+    int32_t gid = multiuser_get_cache_gid(multiuser_get_user_id(uid), multiuser_get_app_id(uid));
+    return (gid != -1) ? gid : uid;
+}
+
+binder::Status InstalldNativeService::fixupAppData(const std::unique_ptr<std::string>& uuid,
+        int32_t flags) {
+    ENFORCE_UID(AID_SYSTEM);
+    CHECK_ARGUMENT_UUID(uuid);
+    std::lock_guard<std::recursive_mutex> lock(mLock);
+
+    const char* uuid_ = uuid ? uuid->c_str() : nullptr;
+    for (auto user : get_known_users(uuid_)) {
+        ATRACE_BEGIN("fixup user");
+        FTS* fts;
+        FTSENT* p;
+        char *argv[] = {
+                (char*) create_data_user_ce_path(uuid_, user).c_str(),
+                (char*) create_data_user_de_path(uuid_, user).c_str(),
+                nullptr
+        };
+        if (!(fts = fts_open(argv, FTS_PHYSICAL | FTS_NOCHDIR | FTS_XDEV, NULL))) {
+            return error("Failed to fts_open");
+        }
+        while ((p = fts_read(fts)) != nullptr) {
+            if (p->fts_info == FTS_D && p->fts_level == 1) {
+                // Track down inodes of cache directories
+                uint64_t raw = 0;
+                ino_t inode_cache = 0;
+                ino_t inode_code_cache = 0;
+                if (getxattr(p->fts_path, kXattrInodeCache, &raw, sizeof(raw)) == sizeof(raw)) {
+                    inode_cache = raw;
+                }
+                if (getxattr(p->fts_path, kXattrInodeCodeCache, &raw, sizeof(raw)) == sizeof(raw)) {
+                    inode_code_cache = raw;
+                }
+
+                // Figure out expected GID of each child
+                FTSENT* child = fts_children(fts, 0);
+                while (child != nullptr) {
+                    if ((child->fts_statp->st_ino == inode_cache)
+                            || (child->fts_statp->st_ino == inode_code_cache)
+                            || !strcmp(child->fts_name, "cache")
+                            || !strcmp(child->fts_name, "code_cache")) {
+                        child->fts_number = get_cache_gid(p->fts_statp->st_uid);
+                    } else {
+                        child->fts_number = p->fts_statp->st_uid;
+                    }
+                    child = child->fts_link;
+                }
+            } else if (p->fts_level >= 2) {
+                if (p->fts_level > 2) {
+                    // Inherit GID from parent once we're deeper into tree
+                    p->fts_number = p->fts_parent->fts_number;
+                }
+
+                uid_t uid = p->fts_parent->fts_statp->st_uid;
+                gid_t cache_gid = get_cache_gid(uid);
+                gid_t expected = p->fts_number;
+                gid_t actual = p->fts_statp->st_gid;
+                if (actual == expected) {
+#if FIXUP_DEBUG
+                    LOG(DEBUG) << "Ignoring " << p->fts_path << " with expected GID " << expected;
+#endif
+                    if (!(flags & FLAG_FORCE)) {
+                        fts_set(fts, p, FTS_SKIP);
+                    }
+                } else if ((actual == uid) || (actual == cache_gid)) {
+                    // Only consider fixing up when current GID belongs to app
+                    if (p->fts_info != FTS_D) {
+                        LOG(INFO) << "Fixing " << p->fts_path << " with unexpected GID " << actual
+                                << " instead of " << expected;
+                    }
+                    switch (p->fts_info) {
+                    case FTS_DP:
+                        // If we're moving towards cache GID, we need to set S_ISGID
+                        if (expected == cache_gid) {
+                            if (chmod(p->fts_path, 02771) != 0) {
+                                PLOG(WARNING) << "Failed to chmod " << p->fts_path;
+                            }
+                        }
+                        // Intentional fall through to also set GID
+                    case FTS_F:
+                        if (chown(p->fts_path, -1, expected) != 0) {
+                            PLOG(WARNING) << "Failed to chown " << p->fts_path;
+                        }
+                        break;
+                    case FTS_SL:
+                    case FTS_SLNONE:
+                        if (lchown(p->fts_path, -1, expected) != 0) {
+                            PLOG(WARNING) << "Failed to chown " << p->fts_path;
+                        }
+                        break;
+                    }
+                } else {
+                    // Ignore all other GID transitions, since they're kinda shady
+                    LOG(WARNING) << "Ignoring " << p->fts_path << " with unexpected GID " << actual
+                            << " instead of " << expected;
+                }
+            }
+        }
+        fts_close(fts);
+        ATRACE_END();
+    }
+    return ok();
+}
+
 binder::Status InstalldNativeService::moveCompleteApp(const std::unique_ptr<std::string>& fromUuid,
         const std::unique_ptr<std::string>& toUuid, const std::string& packageName,
         const std::string& dataAppName, int32_t appId, const std::string& seInfo,
diff --git a/cmds/installd/InstalldNativeService.h b/cmds/installd/InstalldNativeService.h
index 7ad8687..f5b7142 100644
--- a/cmds/installd/InstalldNativeService.h
+++ b/cmds/installd/InstalldNativeService.h
@@ -58,6 +58,8 @@
     binder::Status destroyAppData(const std::unique_ptr<std::string>& uuid,
             const std::string& packageName, int32_t userId, int32_t flags, int64_t ceDataInode);
 
+    binder::Status fixupAppData(const std::unique_ptr<std::string>& uuid, int32_t flags);
+
     binder::Status getAppSize(const std::unique_ptr<std::string>& uuid,
             const std::vector<std::string>& packageNames, int32_t userId, int32_t flags,
             int32_t appId, const std::vector<int64_t>& ceDataInodes,
diff --git a/cmds/installd/binder/android/os/IInstalld.aidl b/cmds/installd/binder/android/os/IInstalld.aidl
index 4195a01..03ff96e 100644
--- a/cmds/installd/binder/android/os/IInstalld.aidl
+++ b/cmds/installd/binder/android/os/IInstalld.aidl
@@ -32,6 +32,8 @@
     void destroyAppData(@nullable @utf8InCpp String uuid, @utf8InCpp String packageName,
             int userId, int flags, long ceDataInode);
 
+    void fixupAppData(@nullable @utf8InCpp String uuid, int flags);
+
     long[] getAppSize(@nullable @utf8InCpp String uuid, in @utf8InCpp String[] packageNames,
             int userId, int flags, int appId, in long[] ceDataInodes,
             in @utf8InCpp String[] codePaths);
diff --git a/cmds/installd/tests/Android.bp b/cmds/installd/tests/Android.bp
index b5b080d..630c1f3 100644
--- a/cmds/installd/tests/Android.bp
+++ b/cmds/installd/tests/Android.bp
@@ -33,3 +33,22 @@
         "libdiskusage",
     ],
 }
+
+cc_test {
+    name: "installd_service_test",
+    clang: true,
+    srcs: ["installd_service_test.cpp"],
+    shared_libs: [
+        "libbase",
+        "libbinder",
+        "libcutils",
+        "liblog",
+        "liblogwrap",
+        "libselinux",
+        "libutils",
+    ],
+    static_libs: [
+        "libinstalld",
+        "libdiskusage",
+    ],
+}
diff --git a/cmds/installd/tests/installd_service_test.cpp b/cmds/installd/tests/installd_service_test.cpp
new file mode 100644
index 0000000..4a1f333
--- /dev/null
+++ b/cmds/installd/tests/installd_service_test.cpp
@@ -0,0 +1,155 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/statvfs.h>
+#include <sys/xattr.h>
+
+#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+#include <cutils/properties.h>
+#include <gtest/gtest.h>
+
+#include "InstalldNativeService.h"
+#include "globals.h"
+#include "utils.h"
+
+using android::base::StringPrintf;
+
+namespace android {
+namespace installd {
+
+constexpr const char* kTestUuid = "TEST";
+
+static constexpr int FLAG_FORCE = 1 << 16;
+
+int get_property(const char *key, char *value, const char *default_value) {
+    return property_get(key, value, default_value);
+}
+
+bool calculate_oat_file_path(char path[PKG_PATH_MAX] ATTRIBUTE_UNUSED,
+        const char *oat_dir ATTRIBUTE_UNUSED,
+        const char *apk_path ATTRIBUTE_UNUSED,
+        const char *instruction_set ATTRIBUTE_UNUSED) {
+    return false;
+}
+
+bool calculate_odex_file_path(char path[PKG_PATH_MAX] ATTRIBUTE_UNUSED,
+        const char *apk_path ATTRIBUTE_UNUSED,
+        const char *instruction_set ATTRIBUTE_UNUSED) {
+    return false;
+}
+
+bool create_cache_path(char path[PKG_PATH_MAX] ATTRIBUTE_UNUSED,
+        const char *src ATTRIBUTE_UNUSED,
+        const char *instruction_set ATTRIBUTE_UNUSED) {
+    return false;
+}
+
+static void mkdir(const char* path, uid_t owner, gid_t group, mode_t mode) {
+    const char* fullPath = StringPrintf("/data/local/tmp/user/0/%s", path).c_str();
+    ::mkdir(fullPath, mode);
+    ::chown(fullPath, owner, group);
+    ::chmod(fullPath, mode);
+}
+
+static void touch(const char* path, uid_t owner, gid_t group, mode_t mode) {
+    int fd = ::open(StringPrintf("/data/local/tmp/user/0/%s", path).c_str(),
+            O_RDWR | O_CREAT, mode);
+    ::fchown(fd, owner, group);
+    ::fchmod(fd, mode);
+    ::close(fd);
+}
+
+static int stat_gid(const char* path) {
+    struct stat buf;
+    ::stat(StringPrintf("/data/local/tmp/user/0/%s", path).c_str(), &buf);
+    return buf.st_gid;
+}
+
+static int stat_mode(const char* path) {
+    struct stat buf;
+    ::stat(StringPrintf("/data/local/tmp/user/0/%s", path).c_str(), &buf);
+    return buf.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO | S_ISGID);
+}
+
+class ServiceTest : public testing::Test {
+protected:
+    InstalldNativeService* service;
+    std::unique_ptr<std::string> testUuid;
+
+    virtual void SetUp() {
+        setenv("ANDROID_LOG_TAGS", "*:v", 1);
+        android::base::InitLogging(nullptr);
+
+        service = new InstalldNativeService();
+        testUuid = std::make_unique<std::string>();
+        *testUuid = std::string(kTestUuid);
+        system("mkdir -p /data/local/tmp/user/0");
+    }
+
+    virtual void TearDown() {
+        delete service;
+        system("rm -rf /data/local/tmp/user");
+    }
+};
+
+TEST_F(ServiceTest, FixupAppData_Upgrade) {
+    LOG(INFO) << "FixupAppData_Upgrade";
+
+    mkdir("com.example", 10000, 10000, 0700);
+    mkdir("com.example/normal", 10000, 10000, 0700);
+    mkdir("com.example/cache", 10000, 10000, 0700);
+    touch("com.example/cache/file", 10000, 10000, 0700);
+
+    service->fixupAppData(testUuid, 0);
+
+    EXPECT_EQ(10000, stat_gid("com.example/normal"));
+    EXPECT_EQ(20000, stat_gid("com.example/cache"));
+    EXPECT_EQ(20000, stat_gid("com.example/cache/file"));
+
+    EXPECT_EQ(0700, stat_mode("com.example/normal"));
+    EXPECT_EQ(02771, stat_mode("com.example/cache"));
+    EXPECT_EQ(0700, stat_mode("com.example/cache/file"));
+}
+
+TEST_F(ServiceTest, FixupAppData_Moved) {
+    LOG(INFO) << "FixupAppData_Moved";
+
+    mkdir("com.example", 10000, 10000, 0700);
+    mkdir("com.example/foo", 10000, 10000, 0700);
+    touch("com.example/foo/file", 10000, 20000, 0700);
+    mkdir("com.example/bar", 10000, 20000, 0700);
+    touch("com.example/bar/file", 10000, 20000, 0700);
+
+    service->fixupAppData(testUuid, 0);
+
+    EXPECT_EQ(10000, stat_gid("com.example/foo"));
+    EXPECT_EQ(20000, stat_gid("com.example/foo/file"));
+    EXPECT_EQ(10000, stat_gid("com.example/bar"));
+    EXPECT_EQ(10000, stat_gid("com.example/bar/file"));
+
+    service->fixupAppData(testUuid, FLAG_FORCE);
+
+    EXPECT_EQ(10000, stat_gid("com.example/foo"));
+    EXPECT_EQ(10000, stat_gid("com.example/foo/file"));
+    EXPECT_EQ(10000, stat_gid("com.example/bar"));
+    EXPECT_EQ(10000, stat_gid("com.example/bar/file"));
+}
+
+}  // namespace installd
+}  // namespace android
diff --git a/cmds/installd/utils.cpp b/cmds/installd/utils.cpp
index 24c0b45..c792082 100644
--- a/cmds/installd/utils.cpp
+++ b/cmds/installd/utils.cpp
@@ -1047,18 +1047,18 @@
     while ((p = fts_read(fts)) != NULL) {
         switch (p->fts_info) {
         case FTS_DP:
-            if (chmod(p->fts_accpath, target_mode) != 0) {
+            if (chmod(p->fts_path, target_mode) != 0) {
                 PLOG(WARNING) << "Failed to chmod " << p->fts_path;
             }
             // Intentional fall through to also set GID
         case FTS_F:
-            if (chown(p->fts_accpath, -1, gid) != 0) {
+            if (chown(p->fts_path, -1, gid) != 0) {
                 PLOG(WARNING) << "Failed to chown " << p->fts_path;
             }
             break;
         case FTS_SL:
         case FTS_SLNONE:
-            if (lchown(p->fts_accpath, -1, gid) != 0) {
+            if (lchown(p->fts_path, -1, gid) != 0) {
                 PLOG(WARNING) << "Failed to chown " << p->fts_path;
             }
             break;
diff --git a/cmds/installd/utils.h b/cmds/installd/utils.h
index 7ebfea2..dd94da9 100644
--- a/cmds/installd/utils.h
+++ b/cmds/installd/utils.h
@@ -31,6 +31,7 @@
 #include <installd_constants.h>
 
 #define MEASURE_DEBUG 0
+#define FIXUP_DEBUG 0
 
 namespace android {
 namespace installd {