[PATCH v8] Add support for stack-protector

Joel Peshkin joel.peshkin at broadcom.com
Thu Jan 14 21:35:35 CET 2021 

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

Signed-off-by: Joel Peshkin <joel.peshkin at broadcom.com>
---
Cc: Simon Glass <sjg at chromium.org>
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>

Changes for v8:
   - Fix commit message
   - Force canary to UL type
Changes for v7:
   - Fix commit message
   - add __builtin_extract_return_addr() calls
Changes for v6:
   - Fix commit message
Changes for v5:
   - Rebase
Changes for v4:
   - Exclude EFI from stackprotector
   - Cleanups of extra includes and declaration
Changes for v3:
   - Move test command to cmd/
   - Update Kconfig names and depends
   - clean up default canary initialization
Changes for v2:
   - Add test command and corresponding config
   - Fixed incorrect description in Kconfig
   - Add unit test
---
 MAINTAINERS                          |  7 +++++++
 Makefile                             |  5 +++++
 cmd/Kconfig                          | 10 ++++++++++
 cmd/Makefile                         |  1 +
 cmd/stackprot_test.c                 | 21 +++++++++++++++++++++
 common/Kconfig                       | 17 +++++++++++++++++
 common/Makefile                      |  2 ++
 common/stackprot.c                   | 19 +++++++++++++++++++
 configs/sandbox_defconfig            | 14 +++++++-------
 scripts/Makefile.spl                 |  6 ++++++
 test/py/tests/test_stackprotector.py | 15 +++++++++++++++
 11 files changed, 110 insertions(+), 7 deletions(-)
 create mode 100644 cmd/stackprot_test.c
 create mode 100644 common/stackprot.c
 create mode 100644 test/py/tests/test_stackprotector.py

diff --git a/MAINTAINERS b/MAINTAINERS
index 26dd254..d3971e8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1024,6 +1024,13 @@ F:	include/sqfs.h
 F:	cmd/sqfs.c
 F:	test/py/tests/test_fs/test_squashfs/
 
+STACKPROTECTOR
+M:	Joel Peshkin <joel.peshkin at 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 at broadcom.com>
 M:	Rayagonda Kokatanur <rayagonda.kokatanur at broadcom.com>
diff --git a/Makefile b/Makefile
index 902a976..65c5cb8 100644
--- a/Makefile
+++ b/Makefile
@@ -677,7 +677,12 @@ 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+
diff --git a/cmd/Kconfig b/cmd/Kconfig
index da86a94..054b2f3 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -2280,6 +2280,16 @@ 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
+	default n
+	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
diff --git a/cmd/Makefile b/cmd/Makefile
index 5b3400a..1d7afea 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -142,6 +142,7 @@ 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
diff --git a/cmd/stackprot_test.c b/cmd/stackprot_test.c
new file mode 100644
index 0000000..6ad287e
--- /dev/null
+++ b/cmd/stackprot_test.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Copyright 2021 Broadcom
+ */
+
+#include <common.h>
+#include <command.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+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", "");
diff --git a/common/Kconfig b/common/Kconfig
index 2bce8c9..6a94045 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -595,6 +595,23 @@ 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"
diff --git a/common/Makefile b/common/Makefile
index bcf352d..fe71e18 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -138,3 +138,5 @@ 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
+
diff --git a/common/stackprot.c b/common/stackprot.c
new file mode 100644
index 0000000..282c564
--- /dev/null
+++ b/common/stackprot.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Copyright 2021 Broadcom
+ */
+
+#include <common.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);
+}
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 58d4ef1..0c82ef2 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -20,11 +20,11 @@ CONFIG_BOOTSTAGE_STASH=y
 CONFIG_BOOTSTAGE_STASH_SIZE=0x4096
 CONFIG_CONSOLE_RECORD=y
 CONFIG_CONSOLE_RECORD_OUT_SIZE=0x1000
-CONFIG_SILENT_CONSOLE=y
 CONFIG_PRE_CONSOLE_BUFFER=y
 CONFIG_LOG_SYSLOG=y
 CONFIG_LOG_ERROR_RETURN=y
 CONFIG_DISPLAY_BOARDINFO_LATE=y
+CONFIG_STACKPROTECTOR=y
 CONFIG_ANDROID_AB=y
 CONFIG_CMD_CPU=y
 CONFIG_CMD_LICENSE=y
@@ -96,6 +96,7 @@ 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
@@ -131,6 +132,7 @@ CONFIG_CPU=y
 CONFIG_DM_DEMO=y
 CONFIG_DM_DEMO_SIMPLE=y
 CONFIG_DM_DEMO_SHAPE=y
+CONFIG_DFU_SF=y
 CONFIG_DMA=y
 CONFIG_DMA_CHANNELS=y
 CONFIG_SANDBOX_DMA=y
@@ -269,14 +271,12 @@ CONFIG_CMD_DHRYSTONE=y
 CONFIG_TPM=y
 CONFIG_LZ4=y
 CONFIG_ERRNO_STR=y
+CONFIG_EFI_RUNTIME_UPDATE_CAPSULE=y
+CONFIG_EFI_CAPSULE_ON_DISK=y
+CONFIG_EFI_CAPSULE_FIRMWARE_FIT=y
+CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y
 CONFIG_EFI_SECURE_BOOT=y
 CONFIG_TEST_FDTDEC=y
 CONFIG_UNIT_TEST=y
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
-#
-CONFIG_DFU_SF=y
-CONFIG_EFI_RUNTIME_UPDATE_CAPSULE=y
-CONFIG_EFI_CAPSULE_ON_DISK=y
-CONFIG_EFI_CAPSULE_FIRMWARE_FIT=y
-CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y
diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
index 87021e2..6725201 100644
--- a/scripts/Makefile.spl
+++ b/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)
diff --git a/test/py/tests/test_stackprotector.py b/test/py/tests/test_stackprotector.py
new file mode 100644
index 0000000..957a2a6
--- /dev/null
+++ b/test/py/tests/test_stackprotector.py
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2021 Broadcom
+
+import pytest
+import signal
+
+ at 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)
+    assert(True)
+
-- 
1.8.3.1

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