From f2b6dc8d2701dc8da5d365a73336d4a8a3dd3478 Mon Sep 17 00:00:00 2001
From: Gabe Black <gabeblack@google.com>
Date: Fri, 5 May 2017 16:50:22 -0700
Subject: base: Teach the socket listeners how to bind to the loopback.

The loopback device will allow access to various services like remote GDB
debugging, connecting to the terminal, etc., without letting external
agents like port scanners connect and disrupting the simulation.

Change-Id: I76dccbf152fa278ae9f342b25f7e345a1329fbe4
Reviewed-on: https://gem5-review.googlesource.com/3080
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
---
 src/base/socket.cc | 14 +++++++++++++-
 src/base/socket.hh |  4 ++++
 2 files changed, 17 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/base/socket.cc b/src/base/socket.cc
index 7a444373b..5ef0f4b9e 100644
--- a/src/base/socket.cc
+++ b/src/base/socket.cc
@@ -40,12 +40,15 @@
 
 #include "base/misc.hh"
 #include "base/types.hh"
+#include "sim/byteswap.hh"
 
 using namespace std;
 
 bool ListenSocket::listeningDisabled = false;
 bool ListenSocket::anyListening = false;
 
+bool ListenSocket::bindToLoopback = false;
+
 void
 ListenSocket::disableAll()
 {
@@ -60,6 +63,14 @@ ListenSocket::allDisabled()
     return listeningDisabled;
 }
 
+void
+ListenSocket::loopbackOnly()
+{
+    if (anyListening)
+        panic("Too late to bind to loopback, already have a listener");
+    bindToLoopback = true;
+}
+
 ////////////////////////////////////////////////////////////////////////
 //
 //
@@ -94,7 +105,8 @@ ListenSocket::listen(int port, bool reuse)
 
     struct sockaddr_in sockaddr;
     sockaddr.sin_family = PF_INET;
-    sockaddr.sin_addr.s_addr = INADDR_ANY;
+    sockaddr.sin_addr.s_addr =
+        htobe<unsigned long>(bindToLoopback ? INADDR_LOOPBACK : INADDR_ANY);
     sockaddr.sin_port = htons(port);
     // finally clear sin_zero
     memset(&sockaddr.sin_zero, 0, sizeof(sockaddr.sin_zero));
diff --git a/src/base/socket.hh b/src/base/socket.hh
index 942318e45..fab7f7576 100644
--- a/src/base/socket.hh
+++ b/src/base/socket.hh
@@ -37,10 +37,14 @@ class ListenSocket
     static bool listeningDisabled;
     static bool anyListening;
 
+    static bool bindToLoopback;
+
   public:
     static void disableAll();
     static bool allDisabled();
 
+    static void loopbackOnly();
+
   protected:
     bool listening;
     int fd;
-- 
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