From 6819c43a05155ce6891e53fc1ef260c3199f5b3a Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Fri, 30 Nov 2018 14:13:27 +0100
Subject: [PATCH] Add stack protector storage to base library

This patch adds the items necessary for building Genode components with
stack protection enabled, but it is not initialized at runtime. They are
provided at the moment as a convenience and do not implement a security
feature.

Fix #3066
---
 repos/base/lib/mk/base-common.inc          |  1 +
 repos/base/lib/symbols/ld                  |  2 ++
 repos/base/src/lib/base/stack_protector.cc | 33 ++++++++++++++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 repos/base/src/lib/base/stack_protector.cc

diff --git a/repos/base/lib/mk/base-common.inc b/repos/base/lib/mk/base-common.inc
index 637f31542..475f0e461 100644
--- a/repos/base/lib/mk/base-common.inc
+++ b/repos/base/lib/mk/base-common.inc
@@ -31,6 +31,7 @@ SRC_CC += trace.cc
 SRC_CC += root_proxy.cc
 SRC_CC += env_session_id_space.cc
 SRC_CC += vm_session.cc
+SRC_CC += stack_protector.cc
 
 INC_DIR += $(REP_DIR)/src/include $(BASE_DIR)/src/include
 
diff --git a/repos/base/lib/symbols/ld b/repos/base/lib/symbols/ld
index 7d835345a..16ef9bd5c 100644
--- a/repos/base/lib/symbols/ld
+++ b/repos/base/lib/symbols/ld
@@ -640,6 +640,8 @@ __cxa_throw_bad_array_new_length T
 __cxa_type_match T
 __dynamic_cast T
 __gxx_personality_v0 T
+__stack_chk_guard B 8
+__stack_chk_fail W
 dl_iterate_phdr T
 dl_unwind_find_exidx T
 genode_argc D 4
diff --git a/repos/base/src/lib/base/stack_protector.cc b/repos/base/src/lib/base/stack_protector.cc
new file mode 100644
index 000000000..118e3c3d2
--- /dev/null
+++ b/repos/base/src/lib/base/stack_protector.cc
@@ -0,0 +1,33 @@
+/*
+ * \brief  Stack protector support
+ * \author Emery Hemingway
+ * \date   2018-11-30
+ *
+ * The following is necessary but not sufficient for stack protection,
+ * the __stack_chk_guard is initialized to zero and must be reinitialized
+ * with a nonce to protect against malicious behavior.
+ */
+
+/*
+ * Copyright (C) 2018 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+/* Genode includes */
+#include <base/log.h>
+#include <base/sleep.h>
+
+extern "C" {
+
+	Genode::uint64_t __stack_chk_guard;
+
+	__attribute__((noreturn)) __attribute__((weak))
+	void __stack_chk_fail(void)
+	{
+		Genode::error("stack protector check failed");
+		Genode::sleep_forever();
+	}
+
+}