1 files changed, 34 insertions, 0 deletions
diff --git a/core/jni/com_android_internal_os_Zygote.cpp b/core/jni/com_android_internal_os_Zygote.cpp
index b431a3f..a1fef4a 100644
--- a/core/jni/com_android_internal_os_Zygote.cpp
+++ b/core/jni/com_android_internal_os_Zygote.cpp
@@ -16,6 +16,8 @@
 
 #define LOG_TAG "Zygote"
 
+#include <sstream>
+
 // sys/mount.h has to come before linux/fs.h due to redefinition of MS_RDONLY, MS_BIND, etc
 #include <sys/mount.h>
 #include <linux/fs.h>
@@ -53,6 +55,7 @@
 #include "ScopedLocalRef.h"
 #include "ScopedPrimitiveArray.h"
 #include "ScopedUtfChars.h"
+#include "fd_utils-inl.h"
 
 #include "nativebridge/native_bridge.h"
 
@@ -78,6 +81,12 @@ static void RuntimeAbort(JNIEnv* env) {
   env->FatalError("RuntimeAbort");
 }
 
+static void RuntimeAbort(JNIEnv* env, int line, const char* msg) {
+  std::ostringstream oss;
+  oss << __FILE__ << ":" << line << ": " << msg;
+  env->FatalError(oss.str().c_str());
+}
+
 // This signal handler is for zygote mode, since the zygote must reap its children
 static void SigChldHandler(int /*signal_number*/) {
   pid_t pid;
@@ -439,6 +448,9 @@ static void SetForkLoad(bool boost) {
 }
 #endif
 
+// The list of open zygote file descriptors.
+static FileDescriptorTable* gOpenFdTable = NULL;
+
 // Utility routine to fork zygote and specialize the child process.
 static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids,
                                      jint debug_flags, jobjectArray javaRlimits,
@@ -453,6 +465,22 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
   SetForkLoad(true);
 #endif
 
+  // Close any logging related FDs before we start evaluating the list of
+  // file descriptors.
+  __android_log_close();
+
+  // If this is the first fork for this zygote, create the open FD table.
+  // If it isn't, we just need to check whether the list of open files has
+  // changed (and it shouldn't in the normal case).
+  if (gOpenFdTable == NULL) {
+    gOpenFdTable = FileDescriptorTable::Create();
+    if (gOpenFdTable == NULL) {
+      RuntimeAbort(env, __LINE__, "Unable to construct file descriptor table.");
+    }
+  } else if (!gOpenFdTable->Restat()) {
+    RuntimeAbort(env, __LINE__, "Unable to restat file descriptor table.");
+  }
+
   pid_t pid = fork();
 
   if (pid == 0) {
@@ -462,6 +490,12 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
     // Clean up any descriptors which must be closed immediately
     DetachDescriptors(env, fdsToClose);
 
+    // Re-open all remaining open file descriptors so that they aren't shared
+    // with the zygote across a fork.
+    if (!gOpenFdTable->ReopenOrDetach()) {
+      RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors.");
+    }
+
     // Keep capabilities across UID change, unless we're staying root.
     if (uid != 0) {
       EnableKeepCapabilities(env);