qemu: Add support for stack canary protection

Allow qemu users to enable stack protection. Since the virt platform
does not provide an RNG, use a basic, timer-based, canary generation,
similarly to FVP.

Increase SRAM size and BL2 size to fit images when stack protection is
enabled.

Notice that stack protection is not enabled by default in qemu.

Fixes ARM-software/tf-issues#568

Signed-off-by: Michalis Pappas <[email protected]>

diff --git a/plat/qemu/include/platform_def.h b/plat/qemu/include/platform_def.h
index f8764fbfe0df2f59c95f8a9d4aefd9cbadf940cf..2f2ca6f1e3f3b1e961f3942d8217f2e650c9716e 100644 (file)
--- a/plat/qemu/include/platform_def.h
+++ b/plat/qemu/include/platform_def.h
@@ -75,7 +75,7 @@
 #define NS_DRAM0_SIZE                  0x3de00000
 
 #define SEC_SRAM_BASE                  0x0e000000
-#define SEC_SRAM_SIZE                  0x00040000
+#define SEC_SRAM_SIZE                  0x00060000
 
 #define SEC_DRAM_BASE                  0x0e100000
 #define SEC_DRAM_SIZE                  0x00f00000
@@ -123,7 +123,7 @@
  * Put BL2 just below BL3-1. BL2_BASE is calculated using the current BL2 debug
  * size plus a little space for growth.
  */
-#define BL2_BASE                       (BL31_BASE - 0x1D000)
+#define BL2_BASE                       (BL31_BASE - 0x25000)
 #define BL2_LIMIT                      BL31_BASE
 
 /*

diff --git a/plat/qemu/platform.mk b/plat/qemu/platform.mk
index 5bfd48afc1d6544992982d6d7252d7dc41fbb947..e11f5042971109cc839b6df2c46d4c170eb3b905 100644 (file)
--- a/plat/qemu/platform.mk
+++ b/plat/qemu/platform.mk
@@ -168,6 +168,10 @@ $(eval $(call TOOL_ADD_IMG,bl32_extra2,--tos-fw-extra2))
 endif
 
 SEPARATE_CODE_AND_RODATA := 1
+ENABLE_STACK_PROTECTOR  := 0
+ifneq ($(ENABLE_STACK_PROTECTOR), 0)
+       PLAT_BL_COMMON_SOURCES += plat/qemu/qemu_stack_protector.c
+endif
 
 # Disable the PSCI platform compatibility layer
 ENABLE_PLAT_COMPAT     :=      0

diff --git a/plat/qemu/qemu_stack_protector.c b/plat/qemu/qemu_stack_protector.c
new file mode 100644 (file)
index 0000000..5b19828
--- /dev/null
+++ b/plat/qemu/qemu_stack_protector.c
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <platform.h>
+#include <stdint.h>
+
+#define RANDOM_CANARY_VALUE ((u_register_t) 3288484550995823360ULL)
+
+u_register_t plat_get_stack_protector_canary(void)
+{
+       /*
+        * Ideally, a random number should be returned instead of the
+        * combination of a timer's value and a compile-time constant.
+        * As the virt platform does not have any random number generator,
+        * this is better than nothing but not necessarily really secure.
+        */
+       return RANDOM_CANARY_VALUE ^ read_cntpct_el0();
+}
+