[PATCH v5] Add support for stack-protector

Joel Peshkin
2021-01-11T23:55:27Z

Cc: Joel Peshkin <joel.peshkin@broadcom.com>,
Simon Glass <sjg@chromium.org>,
Bin Meng <bmeng.cn@gmail.com>,
Jagan Teki <jagan@amarulasolutions.com>,
Kever Yang <kever.yang@rock-chips.com>,
Heinrich Schuchardt <xypron.glpk@gmx.de>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
Usama Arif <usama.arif@arm.com>,
Sam Protsenko <joe.skb7@gmail.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Philippe Reynes <philippe.reynes@softathome.com>,
Eugeniu Rosca <roscaeugeniu@gmail.com>,
Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Joel Peshkin <joel.peshkin@broadcom.com>

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 | 17 +++++++++++++++++
configs/sandbox_defconfig | 14 +++++++-------
scripts/Makefile.spl | 6 ++++++
test/py/tests/test_stackprotector.py | 15 +++++++++++++++
11 files changed, 108 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@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>
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..1f1c3b4
--- /dev/null
+++ b/common/stackprot.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2021 Broadcom
+ */
+
+#include <common.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+unsigned long __stack_chk_guard = (long)(0xfeedf00ddeadbeef & ~0L);
+
+void __stack_chk_fail(void)
+{
+ panic("Stack smashing detected in function:\n%p relocated from %p",
+ __builtin_extract_return_addr(__builtin_return_address(0)),
+ __builtin_return_address(0) - 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