From c4405e9c17bf29a40787d2b9eb1cce01e9838de7 Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@google.com>
Date: Thu, 20 Sep 2018 10:09:27 -0700
Subject: [PATCH] Protect /mnt/scratch from stale umount on userdebug

On userdebug protect /mnt/scratch. On user builds ensure that
/mnt/scratch is considered a stale mount so it can not be used.
vold runs before ro.debuggable is set, so this must be a compile
time decision.

Minor technical debt cleanup associated with using android::base.

Test: compile
Bug: 109821005
Change-Id: I8efdbedfe850dd24daecf03a37aea61de47edc7d
Merged-In: I8efdbedfe850dd24daecf03a37aea61de47edc7d
---
 Android.bp        |  3 +++
 VolumeManager.cpp | 22 ++++++++++++----------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/Android.bp b/Android.bp
index 1e45727..b115bc1 100644
--- a/Android.bp
+++ b/Android.bp
@@ -139,6 +139,9 @@ cc_library_static {
                 "libarcobbvolume",
             ],
         },
+        debuggable: {
+            cppflags: ["-D__ANDROID_DEBUGGABLE__"],
+        },
     },
     shared_libs: [
         "android.hardware.health.storage@1.0",
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index cbe3187..75e28d4 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -64,6 +64,7 @@
 #include "model/EmulatedVolume.h"
 #include "model/ObbVolume.h"
 
+using android::base::StartsWith;
 using android::base::StringPrintf;
 using android::base::unique_fd;
 
@@ -589,10 +590,12 @@ int VolumeManager::unmountAll() {
     mntent* mentry;
     while ((mentry = getmntent(fp)) != NULL) {
         auto test = std::string(mentry->mnt_dir);
-        if ((android::base::StartsWith(test, "/mnt/") &&
-             !android::base::StartsWith(test, "/mnt/vendor") &&
-             !android::base::StartsWith(test, "/mnt/product")) ||
-            android::base::StartsWith(test, "/storage/")) {
+        if ((StartsWith(test, "/mnt/") &&
+#ifdef __ANDROID_DEBUGGABLE__
+             !StartsWith(test, "/mnt/scratch") &&
+#endif
+             !StartsWith(test, "/mnt/vendor") && !StartsWith(test, "/mnt/product")) ||
+            StartsWith(test, "/storage/")) {
             toUnmount.push_front(test);
         }
     }
@@ -608,7 +611,7 @@ int VolumeManager::unmountAll() {
 
 int VolumeManager::mkdirs(const std::string& path) {
     // Only offer to create directories for paths managed by vold
-    if (android::base::StartsWith(path, "/storage/")) {
+    if (StartsWith(path, "/storage/")) {
         // fs_mkdirs() does symlink checking and relative path enforcement
         return fs_mkdirs(path.c_str(), 0700);
     } else {
@@ -630,7 +633,7 @@ static android::status_t getMountPath(uid_t uid, const std::string& name, std::s
             return -EINVAL;
         }
     }
-    *path = android::base::StringPrintf("/mnt/appfuse/%d_%s", uid, name.c_str());
+    *path = StringPrintf("/mnt/appfuse/%d_%s", uid, name.c_str());
     return android::OK;
 }
 
@@ -638,7 +641,7 @@ static android::status_t mountInNamespace(uid_t uid, int device_fd, const std::s
     // Remove existing mount.
     android::vold::ForceUnmount(path);
 
-    const auto opts = android::base::StringPrintf(
+    const auto opts = StringPrintf(
         "fd=%i,"
         "rootmode=40000,"
         "default_permissions,"
@@ -673,7 +676,7 @@ static android::status_t runCommandInNamespace(const std::string& command, uid_t
     }
 
     // Obtains process file descriptor.
-    const std::string pid_str = android::base::StringPrintf("%d", pid);
+    const std::string pid_str = StringPrintf("%d", pid);
     const unique_fd pid_fd(openat(dir.get(), pid_str.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC));
     if (pid_fd.get() == -1) {
         PLOG(ERROR) << "Failed to open /proc/" << pid;
@@ -782,8 +785,7 @@ int VolumeManager::destroyObb(const std::string& volId) {
     return android::OK;
 }
 
-int VolumeManager::mountAppFuse(uid_t uid, pid_t pid, int mountId,
-                                android::base::unique_fd* device_fd) {
+int VolumeManager::mountAppFuse(uid_t uid, pid_t pid, int mountId, unique_fd* device_fd) {
     std::string name = std::to_string(mountId);
 
     // Check mount point name.