From b5dc9dbb30ce3d2e1b88efbd5a9a50ccb01cbc59 Mon Sep 17 00:00:00 2001
From: Ricky Wai <rickywai@google.com>
Date: Fri, 6 Mar 2020 17:45:08 +0000
Subject: [PATCH] Run unshare for app data isolation for instant app

Even MountEmulatedStorage does not run it, isolateAppData should
run it also otherwise it's mounting on root namespace.

Test: atest --instant CookieManagerTest
Test: atest EphemeralTest#testWebViewLoads
Bug: 148966677
Change-Id: I5e2dd8087461efd6b7d566d089c9223f253f3b4f
---
 core/jni/com_android_internal_os_Zygote.cpp | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/core/jni/com_android_internal_os_Zygote.cpp b/core/jni/com_android_internal_os_Zygote.cpp
index 4e139a34c555c..2128f99ff609d 100644
--- a/core/jni/com_android_internal_os_Zygote.cpp
+++ b/core/jni/com_android_internal_os_Zygote.cpp
@@ -133,6 +133,11 @@ static jmethodID gCreateSystemServerClassLoader;
 
 static bool gIsSecurityEnforced = true;
 
+/**
+ * True if the app process is running in its mount namespace.
+ */
+static bool gInAppMountNamespace = false;
+
 /**
  * The maximum number of characters (not including a null terminator) that a
  * process name may contain.
@@ -548,6 +553,17 @@ static void SetGids(JNIEnv* env, jintArray managed_gids, fail_fn_t fail_fn) {
   }
 }
 
+static void ensureInAppMountNamespace(fail_fn_t fail_fn) {
+  if (gInAppMountNamespace) {
+    // In app mount namespace already
+    return;
+  }
+  if (unshare(CLONE_NEWNS) == -1) {
+    fail_fn(CREATE_ERROR("Failed to unshare(): %s", strerror(errno)));
+  }
+  gInAppMountNamespace = true;
+}
+
 // Sets the resource limits via setrlimit(2) for the values in the
 // two-dimensional array of integers that's passed in. The second dimension
 // contains a tuple of length 3: (resource, rlim_cur, rlim_max). nullptr is
@@ -811,9 +827,7 @@ static void MountEmulatedStorage(uid_t uid, jint mount_mode,
   }
 
   // Create a second private mount namespace for our process
-  if (unshare(CLONE_NEWNS) == -1) {
-    fail_fn(CREATE_ERROR("Failed to unshare(): %s", strerror(errno)));
-  }
+  ensureInAppMountNamespace(fail_fn);
 
   // Handle force_mount_namespace with MOUNT_EXTERNAL_NONE.
   if (mount_mode == MOUNT_EXTERNAL_NONE) {
@@ -1319,6 +1333,7 @@ static void isolateAppData(JNIEnv* env, jobjectArray pkg_data_info_list,
   if ((size % 3) != 0) {
     fail_fn(CREATE_ERROR("Wrong pkg_inode_list size %d", size));
   }
+  ensureInAppMountNamespace(fail_fn);
 
   // Mount tmpfs on all possible data directories, so app no longer see the original apps data.
   char internalCePath[PATH_MAX];