Add support for stack-protector

Add support for stack protector for UBOOT, SPL, and TPL
as well as new pytest for stackprotector

Signed-off-by: Joel Peshkin <joel.peshkin@broadcom.com>

Adjust UEFI build flags.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

MAINTAINERS

@@ -1062,6 +1062,13 @@ F:	include/sqfs.h
 F:	cmd/sqfs.c
 F:	test/py/tests/test_fs/test_squashfs/
 
+STACKPROTECTOR
+M:	Joel Peshkin <joel.peshkin@broadcom.com>
+S:	Maintained
+F:	common/stackprot.c
+F:	cmd/stackprot_test.c
+F:	test/py/tests/test_stackprotector.py
+
 TARGET_BCMNS3
 M:	Bharat Gooty <bharat.gooty@broadcom.com>
 M:	Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>

Makefile

@@ -676,7 +676,12 @@ else
 KBUILD_CFLAGS	+= -O2
 endif
 
+ifeq ($(CONFIG_STACKPROTECTOR),y)
+KBUILD_CFLAGS += $(call cc-option,-fstack-protector-strong)
+CFLAGS_EFI += $(call cc-option,-fno-stack-protector)
+else
 KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
+endif
 KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks)
 
 # disable stringop warnings in gcc 8+

arch/arm/config.mk

@@ -11,7 +11,8 @@ CONFIG_STANDALONE_LOAD_ADDR = 0xc100000
 endif
 endif
 
-CFLAGS_NON_EFI := -fno-pic -ffixed-r9 -ffunction-sections -fdata-sections
+CFLAGS_NON_EFI := -fno-pic -ffixed-r9 -ffunction-sections -fdata-sections \
+		  -fstack-protector-strong
 CFLAGS_EFI := -fpic -fshort-wchar
 
 LDFLAGS_FINAL += --gc-sections

arch/riscv/lib/Makefile

@@ -27,6 +27,7 @@ obj-$(CONFIG_SPL_BUILD)	+= spl.o
 obj-y   += fdt_fixup.o
 
 # For building EFI apps
+CFLAGS_NON_EFI := -fstack-protector-strong
 CFLAGS_$(EFI_CRT0) := $(CFLAGS_EFI)
 CFLAGS_REMOVE_$(EFI_CRT0) := $(CFLAGS_NON_EFI)
 

arch/x86/config.mk

@@ -42,7 +42,7 @@ OBJCOPYFLAGS_EFI := -j .text -j .sdata -j .data -j .dynamic -j .dynsym \
 # Compiler flags to be added when building UEFI applications
 CFLAGS_EFI := -fpic -fshort-wchar
 # Compiler flags to be removed when building UEFI applications
-CFLAGS_NON_EFI := -mregparm=3
+CFLAGS_NON_EFI := -mregparm=3 -fstack-protector-strong
 
 ifeq ($(CONFIG_EFI_STUB_64BIT),)
 CFLAGS_EFI += $(call cc-option, -mno-red-zone)

cmd/Kconfig

@@ -2325,6 +2325,15 @@ config CMD_AVB
 	    avb read_part_hex - read data from partition and output to stdout
 	    avb write_part - write data to partition
 	    avb verify - run full verification chain
+
+config CMD_STACKPROTECTOR_TEST
+	bool "Test command for stack protector"
+	depends on STACKPROTECTOR
+	help
+	  Enable stackprot_test command
+	  The stackprot_test command will force a stack overrun to test
+	  the stack smashing detection mechanisms.
+
 endmenu
 
 config CMD_UBI

cmd/Makefile

@@ -144,6 +144,7 @@ obj-$(CONFIG_CMD_SPI) += spi.o
 obj-$(CONFIG_CMD_STRINGS) += strings.o
 obj-$(CONFIG_CMD_SMC) += smccc.o
 obj-$(CONFIG_CMD_SYSBOOT) += sysboot.o pxe_utils.o
+obj-$(CONFIG_CMD_STACKPROTECTOR_TEST) += stackprot_test.o
 obj-$(CONFIG_CMD_TERMINAL) += terminal.o
 obj-$(CONFIG_CMD_TIME) += time.o
 obj-$(CONFIG_CMD_TIMER) += timer.o

cmd/stackprot_test.c

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Copyright 2021 Broadcom
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_test_stackprot_fail(struct cmd_tbl *cmdtp, int flag, int argc,
+				  char *const argv[])
+{
+	char a[128];
+
+	memset(a, 0xa5, 512);
+	return 0;
+}
+
+U_BOOT_CMD(stackprot_test, 1, 1, do_test_stackprot_fail,
+	   "test stack protector fail", "");

common/Kconfig

@@ -618,6 +618,23 @@ config TPL_HASH
 	  and the algorithms it supports are defined in common/hash.c. See
 	  also CMD_HASH for command-line access.
 
+config STACKPROTECTOR
+	bool "Stack Protector buffer overflow detection"
+	default n
+	help
+	  Enable stack smash detection through compiler's stack-protector
+	  canary logic
+
+config SPL_STACKPROTECTOR
+	bool "Stack Protector buffer overflow detection for SPL"
+	depends on STACKPROTECTOR && SPL
+	default n
+
+config TPL_STACKPROTECTOR
+	bool "Stack Protector buffer overflow detection for TPL"
+	depends on STACKPROTECTOR && TPL
+	default n
+
 endmenu
 
 menu "Update support"

common/Makefile

@@ -137,6 +137,7 @@ obj-$(CONFIG_CMD_LOADB) += xyzModem.o
 obj-$(CONFIG_$(SPL_TPL_)YMODEM_SUPPORT) += xyzModem.o
 
 obj-$(CONFIG_AVB_VERIFY) += avb_verify.o
+obj-$(CONFIG_$(SPL_TPL_)STACKPROTECTOR) += stackprot.o
 obj-$(CONFIG_SCP03) += scp03.o
 
 obj-$(CONFIG_QFW) += qfw.o

common/stackprot.c

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Copyright 2021 Broadcom
+ */
+
+#include <common.h>
+#include <asm/global_data.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+unsigned long __stack_chk_guard = (unsigned long)(0xfeedf00ddeadbeef & ~0UL);
+
+void __stack_chk_fail(void)
+{
+	void *ra;
+
+	ra = __builtin_extract_return_addr(__builtin_return_address(0));
+	panic("Stack smashing detected in function:\n%p relocated from %p",
+	      ra, ra - gd->reloc_off);
+}

configs/sandbox_defconfig

@@ -25,6 +25,7 @@ CONFIG_LOG_SYSLOG=y
 CONFIG_LOG_ERROR_RETURN=y
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_MISC_INIT_F=y
+CONFIG_STACKPROTECTOR=y
 CONFIG_ANDROID_AB=y
 CONFIG_CMD_CPU=y
 CONFIG_CMD_LICENSE=y
@@ -97,6 +98,7 @@ CONFIG_CMD_CRAMFS=y
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_SQUASHFS=y
 CONFIG_CMD_MTDPARTS=y
+CONFIG_CMD_STACKPROTECTOR_TEST=y
 CONFIG_MAC_PARTITION=y
 CONFIG_AMIGA_PARTITION=y
 CONFIG_OF_CONTROL=y

scripts/Makefile.spl

@@ -67,6 +67,12 @@ include $(srctree)/scripts/Makefile.lib
 KBUILD_CFLAGS += -ffunction-sections -fdata-sections
 LDFLAGS_FINAL += --gc-sections
 
+ifeq ($(CONFIG_$(SPL_TPL_)STACKPROTECTOR),y)
+KBUILD_CFLAGS += -fstack-protector-strong
+else
+KBUILD_CFLAGS += -fno-stack-protector
+endif
+
 # FIX ME
 cpp_flags := $(KBUILD_CPPFLAGS) $(PLATFORM_CPPFLAGS) $(UBOOTINCLUDE) \
 							$(NOSTDINC_FLAGS)

test/py/tests/test_stackprotector.py

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2021 Broadcom
+
+import pytest
+import signal
+
+@pytest.mark.buildconfigspec('cmd_stackprotector_test')
+def test_stackprotector(u_boot_console):
+    """Test that the stackprotector function works."""
+
+    u_boot_console.run_command('stackprot_test',wait_for_prompt=False)
+    expected_response = 'Stack smashing detected'
+    u_boot_console.wait_for(expected_response)
+    u_boot_console.restart_uboot()