Merge changes from topic 'kill_debuggerd'

* changes:
  Switch android.os.Debug to libdebuggerd_client.
  app_process: don't use PR_SET_NO_NEW_PRIVS.
  Remove peercred check from NativeCrashListener.

cmds/app_process/app_main.cpp

@@ -184,10 +184,6 @@ static const char ZYGOTE_NICE_NAME[] = "zygote";
 
 int main(int argc, char* const argv[])
 {
-    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
-        LOG_ALWAYS_FATAL("PR_SET_NO_NEW_PRIVS failed: %s", strerror(errno));
-    }
-
     if (!LOG_NDEBUG) {
       String8 argv_String;
       for (int i = 0; i < argc; ++i) {

core/jni/Android.mk

@@ -223,6 +223,7 @@ LOCAL_SHARED_LIBRARIES := \
     libnativehelper \
     liblog \
     libcutils \
+    libdebuggerd_client \
     libutils \
     libbinder \
     libnetutils \

core/jni/android_os_Debug.cpp

@@ -33,7 +33,7 @@
 #include <string>
 
 #include <android-base/stringprintf.h>
-#include <cutils/debugger.h>
+#include <debuggerd/client.h>
 #include <log/log.h>
 #include <utils/misc.h>
 #include <utils/String8.h>

services/core/java/com/android/server/am/NativeCrashListener.java

@@ -20,7 +20,6 @@ import android.app.ApplicationErrorReport.CrashInfo;
 import android.system.ErrnoException;
 import android.system.Os;
 import android.system.StructTimeval;
-import android.system.StructUcred;
 import android.system.UnixSocketAddress;
 import android.util.Slog;
 
@@ -105,9 +104,9 @@ final class NativeCrashListener extends Thread {
 
         if (DEBUG) Slog.i(TAG, "Starting up");
 
-        // The file system entity for this socket is created with 0700 perms, owned
-        // by system:system.  debuggerd runs as root, so is capable of connecting to
-        // it, but 3rd party apps cannot.
+        // The file system entity for this socket is created with 0777 perms, owned
+        // by system:system. selinux restricts things so that only crash_dump can
+        // access it.
         {
             File socketFile = new File(DEBUGGERD_SOCKET_PATH);
             if (socketFile.exists()) {
@@ -121,6 +120,7 @@ final class NativeCrashListener extends Thread {
                     DEBUGGERD_SOCKET_PATH);
             Os.bind(serverFd, sockAddr);
             Os.listen(serverFd, 1);
+            Os.chmod(DEBUGGERD_SOCKET_PATH, 0777);
 
             while (true) {
                 FileDescriptor peerFd = null;
@@ -129,19 +129,14 @@ final class NativeCrashListener extends Thread {
                     peerFd = Os.accept(serverFd, null /* peerAddress */);
                     if (MORE_DEBUG) Slog.v(TAG, "Got debuggerd socket " + peerFd);
                     if (peerFd != null) {
-                        // Only the superuser is allowed to talk to us over this socket
-                        StructUcred credentials =
-                                Os.getsockoptUcred(peerFd, SOL_SOCKET, SO_PEERCRED);
-                        if (credentials.uid == 0) {
-                            // the reporting thread may take responsibility for
-                            // acking the debugger; make sure we play along.
-                            consumeNativeCrashData(peerFd);
-                        }
+                        // the reporting thread may take responsibility for
+                        // acking the debugger; make sure we play along.
+                        consumeNativeCrashData(peerFd);
                     }
                 } catch (Exception e) {
                     Slog.w(TAG, "Error handling connection", e);
                 } finally {
-                    // Always ack debuggerd's connection to us.  The actual
+                    // Always ack crash_dump's connection to us.  The actual
                     // byte written is irrelevant.
                     if (peerFd != null) {
                         try {
@@ -194,7 +189,7 @@ final class NativeCrashListener extends Thread {
         return totalRead;
     }
 
-    // Read the crash report from the debuggerd connection
+    // Read a crash report from the connection
     void consumeNativeCrashData(FileDescriptor fd) {
         if (MORE_DEBUG) Slog.i(TAG, "debuggerd connected");
         final byte[] buf = new byte[4096];
@@ -205,6 +200,10 @@ final class NativeCrashListener extends Thread {
             Os.setsockoptTimeval(fd, SOL_SOCKET, SO_RCVTIMEO, timeout);
             Os.setsockoptTimeval(fd, SOL_SOCKET, SO_SNDTIMEO, timeout);
 
+            // The socket is guarded by an selinux neverallow rule that only
+            // permits crash_dump to connect to it. This allows us to trust the
+            // received values.
+
             // first, the pid and signal number
             int headerBytes = readExactly(fd, buf, 0, 8);
             if (headerBytes != 8) {